[v6,6/8] IIO: add STM32 timer trigger driver

Commit Message

Benjamin Gaignard Dec. 9, 2016, 2:15 p.m. UTC

Timers IPs can be used to generate triggers for other IPs like
DAC, ADC or other timers.
Each trigger may result of timer internals signals like counter enable,
reset or edge, this configuration could be done through "master_mode"
device attribute.

A timer device could be triggered by other timers, we use the trigger
name and is_stm32_iio_timer_trigger() function to distinguish them
and configure IP input switch.

Timer may also decide on which event (edge, level) they could
be activated by a trigger, this configuration is done by writing in
"slave_mode" device attribute.

Since triggers could also be used by DAC or ADC their names are defined
in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will be able
to configure themselves in valid_trigger function

Trigger have a "sampling_frequency" attribute which allow to configure
timer sampling frequency without using PWM interface

version 5:
- simplify tables of triggers
- only create an IIO device when needed

version 4:
- get triggers configuration from "reg" in DT
- add tables of triggers
- sampling frequency is enable/disable when writing in trigger
  sampling_frequency attribute
- no more use of interruptions

version 3:
- change compatible to "st,stm32-timer-trigger"
- fix attributes access right
- use string instead of int for master_mode and slave_mode
- document device attributes in sysfs-bus-iio-timer-stm32

version 2:
- keep only one compatible
- use st,input-triggers-names and st,output-triggers-names
  to know which triggers are accepted and/or create by the device

Signed-off-by: Benjamin Gaignard <[e-mail]>
---
 .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
 drivers/iio/Kconfig                                |   2 +-
 drivers/iio/Makefile                               |   1 +
 drivers/iio/timer/Kconfig                          |  13 +
 drivers/iio/timer/Makefile                         |   1 +
 drivers/iio/timer/stm32-timer-trigger.c            | 466 +++++++++++++++++++++
 drivers/iio/trigger/Kconfig                        |   1 -
 include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
 8 files changed, 599 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
 create mode 100644 drivers/iio/timer/Kconfig
 create mode 100644 drivers/iio/timer/Makefile
 create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
 create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h

Comments

Jonathan Cameron Dec. 30, 2016, 9:12 p.m. UTC | #1

On 09/12/16 14:15, Benjamin Gaignard wrote:
> Timers IPs can be used to generate triggers for other IPs like
> DAC, ADC or other timers.
> Each trigger may result of timer internals signals like counter enable,
> reset or edge, this configuration could be done through "master_mode"
> device attribute.
> 
> A timer device could be triggered by other timers, we use the trigger
> name and is_stm32_iio_timer_trigger() function to distinguish them
> and configure IP input switch.
> 
> Timer may also decide on which event (edge, level) they could
> be activated by a trigger, this configuration is done by writing in
> "slave_mode" device attribute.
> 
> Since triggers could also be used by DAC or ADC their names are defined
> in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will be able
> to configure themselves in valid_trigger function
> 
> Trigger have a "sampling_frequency" attribute which allow to configure
> timer sampling frequency without using PWM interface
> 
> version 5:
> - simplify tables of triggers
> - only create an IIO device when needed
> 
> version 4:
> - get triggers configuration from "reg" in DT
> - add tables of triggers
> - sampling frequency is enable/disable when writing in trigger
>   sampling_frequency attribute
> - no more use of interruptions
> 
> version 3:
> - change compatible to "st,stm32-timer-trigger"
> - fix attributes access right
> - use string instead of int for master_mode and slave_mode
> - document device attributes in sysfs-bus-iio-timer-stm32
> 
> version 2:
> - keep only one compatible
> - use st,input-triggers-names and st,output-triggers-names
>   to know which triggers are accepted and/or create by the device
Firstly, sorry it has taken me so long to get back to this.

I'm still not keen on this use of iio_device elements just to act as
glue between triggers.  I think we need to work out a more light weight
way to do this.  As you are only using them for validation and to provide
somewhere to hang the control attibutes off, there is nothing stopping us
moving that over to the iio_trigger instead which would avoid the messy
duality going on here.

I might still be missing something though!

You would only I think need 3 attributes

parrent_trigger
and something like your master_mode and slave_mode attributes.

The parrent_trigger would need some validation etc, but if we keep it
within this driver initially that won't be hard to do. Checking the device
parent matches will do most of it.

Jonathan
> 
> Signed-off-by: Benjamin Gaignard <[e-mail]>
> ---
>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
>  drivers/iio/Kconfig                                |   2 +-
>  drivers/iio/Makefile                               |   1 +
>  drivers/iio/timer/Kconfig                          |  13 +
>  drivers/iio/timer/Makefile                         |   1 +
>  drivers/iio/timer/stm32-timer-trigger.c            | 466 +++++++++++++++++++++
>  drivers/iio/trigger/Kconfig                        |   1 -
>  include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
>  8 files changed, 599 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>  create mode 100644 drivers/iio/timer/Kconfig
>  create mode 100644 drivers/iio/timer/Makefile
>  create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
>  create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> new file mode 100644
> index 0000000..26583dd
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> @@ -0,0 +1,55 @@
> +What:		/sys/bus/iio/devices/iio:deviceX/master_mode_available
> +KernelVersion:	4.10
> +Contact:	[e-mail]
> +Description:
> +		Reading returns the list possible master modes which are:
> +		- "reset"     :	The UG bit from the TIMx_EGR register is used as trigger output (TRGO).
> +		- "enable"    : The Counter Enable signal CNT_EN is used as trigger output.
> +		- "update"    : The update event is selected as trigger output.
> +				For instance a master timer can then be used as a prescaler for a slave timer.
> +		- "compare_pulse" : The trigger output send a positive pulse when the CC1IF flag is to be set.
> +		- "OC1REF"    : OC1REF signal is used as trigger output.
> +		- "OC2REF"    : OC2REF signal is used as trigger output.
> +		- "OC3REF"    : OC3REF signal is used as trigger output.
> +		- "OC4REF"    : OC4REF signal is used as trigger output.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/master_mode
> +KernelVersion:	4.10
> +Contact:	[e-mail]
> +Description:
> +		Reading returns the current master modes.
> +		Writing set the master mode
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/slave_mode_available
> +KernelVersion:	4.10
> +Contact:	[e-mail]
> +Description:
> +		Reading returns the list possible slave modes which are:
> +		- "disabled"  : The prescaler is clocked directly by the internal clock.
> +		- "encoder_1" : Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
> +		- "encoder_2" : Counter counts up/down on TI1FP2 edge depending on TI2FP1 level.
> +		- "encoder_3" : Counter counts up/down on both TI1FP1 and TI2FP2 edges depending
> +				on the level of the other input.
> +		- "reset"     : Rising edge of the selected trigger input reinitializes the counter
> +				and generates an update of the registers.
> +		- "gated"     : The counter clock is enabled when the trigger input is high.
> +				The counter stops (but is not reset) as soon as the trigger becomes low.
> +				Both start and stop of the counter are controlled.
> +		- "trigger"   : The counter starts at a rising edge of the trigger TRGI (but it is not
> +				reset). Only the start of the counter is controlled.
> +		- "external_clock": Rising edges of the selected trigger (TRGI) clock the counter.
> +
> +What:		/sys/bus/iio/devices/iio:deviceX/slave_mode
> +KernelVersion:	4.10
> +Contact:	[e-mail]
> +Description:
> +		Reading returns the current slave mode.
> +		Writing set the slave mode
> +
> +What:		/sys/bus/iio/devices/triggerX/sampling_frequency
> +KernelVersion:	4.10
> +Contact:	[e-mail]
> +Description:
> +		Reading returns the current sampling frequency.
> +		Writing an value different of 0 set and start sampling.
> +		Writing 0 stop sampling.
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 6743b18..2de2a80 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -90,5 +90,5 @@ source "drivers/iio/potentiometer/Kconfig"
>  source "drivers/iio/pressure/Kconfig"
>  source "drivers/iio/proximity/Kconfig"
>  source "drivers/iio/temperature/Kconfig"
> -
> +source "drivers/iio/timer/Kconfig"
>  endif # IIO
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index 87e4c43..b797c08 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -32,4 +32,5 @@ obj-y += potentiometer/
>  obj-y += pressure/
>  obj-y += proximity/
>  obj-y += temperature/
> +obj-y += timer/
>  obj-y += trigger/
> diff --git a/drivers/iio/timer/Kconfig b/drivers/iio/timer/Kconfig
> new file mode 100644
> index 0000000..e3c21f2
> --- /dev/null
> +++ b/drivers/iio/timer/Kconfig
> @@ -0,0 +1,13 @@
> +#
> +# Timers drivers
> +
> +menu "Timers"
> +
> +config IIO_STM32_TIMER_TRIGGER
> +	tristate "STM32 Timer Trigger"
> +	depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) || COMPILE_TEST
> +	select IIO_TRIGGERED_EVENT
> +	help
> +	  Select this option to enable STM32 Timer Trigger
> +
> +endmenu
> diff --git a/drivers/iio/timer/Makefile b/drivers/iio/timer/Makefile
> new file mode 100644
> index 0000000..4ad95ec9
> --- /dev/null
> +++ b/drivers/iio/timer/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
> diff --git a/drivers/iio/timer/stm32-timer-trigger.c b/drivers/iio/timer/stm32-timer-trigger.c
> new file mode 100644
> index 0000000..8d16e8f
> --- /dev/null
> +++ b/drivers/iio/timer/stm32-timer-trigger.c
> @@ -0,0 +1,466 @@
> +/*
> + * Copyright (C) STMicroelectronics 2016
> + *
> + * Author: Benjamin Gaignard <[e-mail]>
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + */
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/timer/stm32-timer-trigger.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/triggered_event.h>
> +#include <linux/interrupt.h>
> +#include <linux/mfd/stm32-timers.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +#define MAX_TRIGGERS 6
> +#define MAX_VALIDS 5
> +
> +/* List the triggers created by each timer */
> +static const void *triggers_table[][MAX_TRIGGERS] = {
> +	{ TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
> +	{ TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
> +	{ TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
> +	{ TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
> +	{ TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
> +	{ TIM6_TRGO,},
> +	{ TIM7_TRGO,},
> +	{ TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
> +	{ TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
> +	{ TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
> +};
> +
> +/* List the triggers accepted by each timer */
> +static const void *valids_table[][MAX_VALIDS] = {
> +	{ TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
> +	{ TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
> +	{ TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
> +	{ TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
> +	{ TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
> +	{ }, /* timer 6 */
> +	{ }, /* timer 7 */
> +	{ TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
> +	{ TIM2_TRGO, TIM3_TRGO,},
> +	{ TIM4_TRGO, TIM5_TRGO,},
> +};
> +
> +struct stm32_timer_trigger {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct clk *clk;
> +	u32 max_arr;
> +	const void *triggers;
> +	const void *valids;
> +};
> +
> +static int stm32_timer_start(struct stm32_timer_trigger *priv,
> +			     unsigned int frequency)
> +{
> +	unsigned long long prd, div;
> +	int prescaler = 0;
> +	u32 ccer, cr1;
> +
> +	/* Period and prescaler values depends of clock rate */
> +	div = (unsigned long long)clk_get_rate(priv->clk);
> +
> +	do_div(div, frequency);
> +
> +	prd = div;
> +
> +	/*
> +	 * Increase prescaler value until we get a result that fit
> +	 * with auto reload register maximum value.
> +	 */
> +	while (div > priv->max_arr) {
> +		prescaler++;
> +		div = prd;
> +		do_div(div, (prescaler + 1));
> +	}
> +	prd = div;
> +
> +	if (prescaler > MAX_TIM_PSC) {
> +		dev_err(priv->dev, "prescaler exceeds the maximum value\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Check if nobody else use the timer */
> +	regmap_read(priv->regmap, TIM_CCER, &ccer);
> +	if (ccer & TIM_CCER_CCXE)
> +		return -EBUSY;
> +
> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
> +	if (!(cr1 & TIM_CR1_CEN))
> +		clk_enable(priv->clk);
> +
> +	regmap_write(priv->regmap, TIM_PSC, prescaler);
> +	regmap_write(priv->regmap, TIM_ARR, prd - 1);
> +	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
> +
> +	/* Force master mode to update mode */
> +	regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
> +
> +	/* Make sure that registers are updated */
> +	regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
> +
> +	/* Enable controller */
> +	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
> +
> +	return 0;
> +}
> +
> +static void stm32_timer_stop(struct stm32_timer_trigger *priv)
> +{
> +	u32 ccer, cr1;
> +
> +	regmap_read(priv->regmap, TIM_CCER, &ccer);
> +	if (ccer & TIM_CCER_CCXE)
> +		return;
> +
> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
> +	if (cr1 & TIM_CR1_CEN)
> +		clk_disable(priv->clk);
> +
> +	/* Stop timer */
> +	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
> +	regmap_write(priv->regmap, TIM_PSC, 0);
> +	regmap_write(priv->regmap, TIM_ARR, 0);
> +}
> +
> +static ssize_t stm32_tt_store_frequency(struct device *dev,
> +					struct device_attribute *attr,
> +					const char *buf, size_t len)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
> +	unsigned int freq;
> +	int ret;
> +
> +	ret = kstrtouint(buf, 10, &freq);
> +	if (ret)
> +		return ret;
> +
> +	if (freq == 0) {
> +		stm32_timer_stop(priv);
> +	} else {
> +		ret = stm32_timer_start(priv, freq);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return len;
> +}
> +
> +static ssize_t stm32_tt_read_frequency(struct device *dev,
> +				       struct device_attribute *attr, char *buf)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
> +	u32 psc, arr, cr1;
> +	unsigned long long freq = 0;
> +
> +	regmap_read(priv->regmap, TIM_CR1, &cr1);
> +	regmap_read(priv->regmap, TIM_PSC, &psc);
> +	regmap_read(priv->regmap, TIM_ARR, &arr);
> +
> +	if (psc && arr && (cr1 & TIM_CR1_CEN)) {
> +		freq = (unsigned long long)clk_get_rate(priv->clk);
> +		do_div(freq, psc);
> +		do_div(freq, arr);
> +	}
> +
> +	return sprintf(buf, "%d\n", (unsigned int)freq);
> +}
> +
> +static IIO_DEV_ATTR_SAMP_FREQ(0660,
> +			      stm32_tt_read_frequency,
> +			      stm32_tt_store_frequency);
> +
> +static struct attribute *stm32_trigger_attrs[] = {
> +	&iio_dev_attr_sampling_frequency.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group stm32_trigger_attr_group = {
> +	.attrs = stm32_trigger_attrs,
> +};
> +
> +static const struct attribute_group *stm32_trigger_attr_groups[] = {
> +	&stm32_trigger_attr_group,
> +	NULL,
> +};
> +
> +static char *master_mode_table[] = {
> +	"reset",
> +	"enable",
> +	"update",
> +	"compare_pulse",
> +	"OC1REF",
> +	"OC2REF",
> +	"OC3REF",
> +	"OC4REF"
> +};
> +
> +static ssize_t stm32_tt_show_master_mode(struct device *dev,
> +					 struct device_attribute *attr,
> +					 char *buf)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	u32 cr2;
> +
> +	regmap_read(priv->regmap, TIM_CR2, &cr2);
> +	cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
> +
> +	return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
> +}
> +
> +static ssize_t stm32_tt_store_master_mode(struct device *dev,
> +					  struct device_attribute *attr,
> +					  const char *buf, size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
> +		if (!strncmp(master_mode_table[i], buf,
> +			     strlen(master_mode_table[i]))) {
> +			regmap_update_bits(priv->regmap, TIM_CR2,
> +					   TIM_CR2_MMS, i << TIM_CR2_MMS_SHIFT);
> +			return len;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static IIO_CONST_ATTR(master_mode_available,
> +	"reset enable update compare_pulse OC1REF OC2REF OC3REF OC4REF");
> +
> +static IIO_DEVICE_ATTR(master_mode, 0660,
> +		       stm32_tt_show_master_mode,
> +		       stm32_tt_store_master_mode,
> +		       0);
> +
> +static char *slave_mode_table[] = {
> +	"disabled",
> +	"encoder_1",
> +	"encoder_2",
> +	"encoder_3",
> +	"reset",
> +	"gated",
> +	"trigger",
> +	"external_clock",
> +};
> +
> +static ssize_t stm32_tt_show_slave_mode(struct device *dev,
> +					struct device_attribute *attr,
> +					char *buf)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	u32 smcr;
> +
> +	regmap_read(priv->regmap, TIM_SMCR, &smcr);
> +	smcr &= TIM_SMCR_SMS;
> +
> +	return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
> +}
> +
> +static ssize_t stm32_tt_store_slave_mode(struct device *dev,
> +					 struct device_attribute *attr,
> +					 const char *buf, size_t len)
> +{
> +	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
> +		if (!strncmp(slave_mode_table[i], buf,
> +			     strlen(slave_mode_table[i]))) {
> +			regmap_update_bits(priv->regmap,
> +					   TIM_SMCR, TIM_SMCR_SMS, i);
> +			return len;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static IIO_CONST_ATTR(slave_mode_available,
> +"disabled encoder_1 encoder_2 encoder_3 reset gated trigger external_clock");
> +
> +static IIO_DEVICE_ATTR(slave_mode, 0660,
> +		       stm32_tt_show_slave_mode,
> +		       stm32_tt_store_slave_mode,
> +		       0);
> +
> +static struct attribute *stm32_timer_attrs[] = {
> +	&iio_dev_attr_master_mode.dev_attr.attr,
> +	&iio_const_attr_master_mode_available.dev_attr.attr,
> +	&iio_dev_attr_slave_mode.dev_attr.attr,
> +	&iio_const_attr_slave_mode_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group stm32_timer_attr_group = {
> +	.attrs = stm32_timer_attrs,
> +};
> +
> +static const struct iio_trigger_ops timer_trigger_ops = {
> +	.owner = THIS_MODULE,
> +};
> +
> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
> +{
> +	int ret;
> +	const char * const *cur = priv->triggers;
> +
> +	while (cur && *cur) {
> +		struct iio_trigger *trig;
> +
> +		trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur);
> +		if  (!trig)
> +			return -ENOMEM;
> +
> +		trig->dev.parent = priv->dev->parent;
> +		trig->ops = &timer_trigger_ops;
> +		trig->dev.groups = stm32_trigger_attr_groups;
> +		iio_trigger_set_drvdata(trig, priv);
> +
> +		ret = devm_iio_trigger_register(priv->dev, trig);
> +		if (ret)
> +			return ret;
> +		cur++;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * is_stm32_timer_trigger
> + * @trig: trigger to be checked
> + *
> + * return true if the trigger is a valid stm32 iio timer trigger
> + * either return false
> + */
> +bool is_stm32_timer_trigger(struct iio_trigger *trig)
> +{
> +	return (trig->ops == &timer_trigger_ops);
> +}
> +EXPORT_SYMBOL(is_stm32_timer_trigger);
> +
> +static int stm32_validate_trigger(struct iio_dev *indio_dev,
> +				  struct iio_trigger *trig)
> +{
> +	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
> +	const char * const *cur = priv->valids;
> +	unsigned int i = 0;
> +
> +	if (!is_stm32_timer_trigger(trig))
> +		return -EINVAL;
> +
> +	while (cur && *cur) {
> +		if (!strncmp(trig->name, *cur, strlen(trig->name))) {
> +			regmap_update_bits(priv->regmap,
> +					   TIM_SMCR, TIM_SMCR_TS,
> +					   i << TIM_SMCR_TS_SHIFT);
> +			return 0;
> +		}
> +		cur++;
> +		i++;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info stm32_trigger_info = {
> +	.driver_module = THIS_MODULE,
> +	.validate_trigger = stm32_validate_trigger,
> +	.attrs = &stm32_timer_attr_group,
> +};
> +
> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
> +{
> +	struct iio_dev *indio_dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev,
> +					  sizeof(struct stm32_timer_trigger));
> +	if (!indio_dev)
> +		return NULL;
> +
> +	indio_dev->name = dev_name(dev);
> +	indio_dev->dev.parent = dev;
> +	indio_dev->info = &stm32_trigger_info;
> +	indio_dev->modes = INDIO_EVENT_TRIGGERED;
> +	indio_dev->num_channels = 0;
> +	indio_dev->dev.of_node = dev->of_node;
> +
> +	ret = devm_iio_device_register(dev, indio_dev);
> +	if (ret)
> +		return NULL;
> +
> +	return iio_priv(indio_dev);
> +}
> +
> +static int stm32_timer_trigger_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct stm32_timer_trigger *priv;
> +	struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
> +	unsigned int index;
> +	int ret;
> +
> +	if (of_property_read_u32(dev->of_node, "reg", &index))
> +		return -EINVAL;
> +
> +	if (index >= ARRAY_SIZE(triggers_table))
> +		return -EINVAL;
> +
> +	/* Create an IIO device only if we have triggers to be validated */
> +	if (*valids_table[index])
> +		priv = stm32_setup_iio_device(dev);

I still don't like this. Really feels like we shouldn't be creating an
iio device with all the bagage that carries just to allow us to do the
trigger trees.  We ought to have a much more light weight solution for this
functionality - we aren't typically even using the interrupt tree stuff
that the triggers for devices are all really about.

A simpler approach of allowing each trigger the option of a parent seems like
it would be cleaner.  Could be done entirely within this driver in the first
instance.  Basically it would just look like your master and slave attributes
but have those under triggerX not iio:deviceX.

We can work out how to make it more generic later - including perhaps the
option to trigger from triggers outside this driver, using some parallel
infrastructure to the device triggering.


> +	else
> +		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->dev = dev;
> +	priv->regmap = ddata->regmap;
> +	priv->clk = ddata->clk;
> +	priv->max_arr = ddata->max_arr;
> +	priv->triggers = triggers_table[index];
> +	priv->valids = valids_table[index];
> +
> +	ret = stm32_setup_iio_triggers(priv);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, priv);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id stm32_trig_of_match[] = {
> +	{ .compatible = "st,stm32-timer-trigger", },
> +	{ /* end node */ },
> +};
> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
> +
> +static struct platform_driver stm32_timer_trigger_driver = {
> +	.probe = stm32_timer_trigger_probe,
> +	.driver = {
> +		.name = "stm32-timer-trigger",
> +		.of_match_table = stm32_trig_of_match,
> +	},
> +};
> +module_platform_driver(stm32_timer_trigger_driver);
> +
> +MODULE_ALIAS("platform: stm32-timer-trigger");
> +MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
> index 809b2e7..f2af4fe 100644
> --- a/drivers/iio/trigger/Kconfig
> +++ b/drivers/iio/trigger/Kconfig
> @@ -46,5 +46,4 @@ config IIO_SYSFS_TRIGGER
>  
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called iio-trig-sysfs.
> -
Clean this up.
>  endmenu
> diff --git a/include/linux/iio/timer/stm32-timer-trigger.h b/include/linux/iio/timer/stm32-timer-trigger.h
> new file mode 100644
> index 0000000..55535ae
> --- /dev/null
> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
> @@ -0,0 +1,62 @@
> +/*
> + * Copyright (C) STMicroelectronics 2016
> + *
> + * Author: Benjamin Gaignard <[e-mail]>
> + *
> + * License terms:  GNU General Public License (GPL), version 2
> + */
> +
> +#ifndef _STM32_TIMER_TRIGGER_H_
> +#define _STM32_TIMER_TRIGGER_H_
> +
> +#define TIM1_TRGO	"tim1_trgo"
> +#define TIM1_CH1	"tim1_ch1"
> +#define TIM1_CH2	"tim1_ch2"
> +#define TIM1_CH3	"tim1_ch3"
> +#define TIM1_CH4	"tim1_ch4"
> +
> +#define TIM2_TRGO	"tim2_trgo"
> +#define TIM2_CH1	"tim2_ch1"
> +#define TIM2_CH2	"tim2_ch2"
> +#define TIM2_CH3	"tim2_ch3"
> +#define TIM2_CH4	"tim2_ch4"
> +
> +#define TIM3_TRGO	"tim3_trgo"
> +#define TIM3_CH1	"tim3_ch1"
> +#define TIM3_CH2	"tim3_ch2"
> +#define TIM3_CH3	"tim3_ch3"
> +#define TIM3_CH4	"tim3_ch4"
> +
> +#define TIM4_TRGO	"tim4_trgo"
> +#define TIM4_CH1	"tim4_ch1"
> +#define TIM4_CH2	"tim4_ch2"
> +#define TIM4_CH3	"tim4_ch3"
> +#define TIM4_CH4	"tim4_ch4"
> +
> +#define TIM5_TRGO	"tim5_trgo"
> +#define TIM5_CH1	"tim5_ch1"
> +#define TIM5_CH2	"tim5_ch2"
> +#define TIM5_CH3	"tim5_ch3"
> +#define TIM5_CH4	"tim5_ch4"
> +
> +#define TIM6_TRGO	"tim6_trgo"
> +
> +#define TIM7_TRGO	"tim7_trgo"
> +
> +#define TIM8_TRGO	"tim8_trgo"
> +#define TIM8_CH1	"tim8_ch1"
> +#define TIM8_CH2	"tim8_ch2"
> +#define TIM8_CH3	"tim8_ch3"
> +#define TIM8_CH4	"tim8_ch4"
> +
> +#define TIM9_TRGO	"tim9_trgo"
> +#define TIM9_CH1	"tim9_ch1"
> +#define TIM9_CH2	"tim9_ch2"
> +
> +#define TIM12_TRGO	"tim12_trgo"
> +#define TIM12_CH1	"tim12_ch1"
> +#define TIM12_CH2	"tim12_ch2"
> +
> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
> +
> +#endif
>

Benjamin Gaignard Jan. 2, 2017, 8:46 a.m. UTC | #2

2016-12-30 22:12 GMT+01:00 Jonathan Cameron <[e-mail]>:
> On 09/12/16 14:15, Benjamin Gaignard wrote:
>> Timers IPs can be used to generate triggers for other IPs like
>> DAC, ADC or other timers.
>> Each trigger may result of timer internals signals like counter enable,
>> reset or edge, this configuration could be done through "master_mode"
>> device attribute.
>>
>> A timer device could be triggered by other timers, we use the trigger
>> name and is_stm32_iio_timer_trigger() function to distinguish them
>> and configure IP input switch.
>>
>> Timer may also decide on which event (edge, level) they could
>> be activated by a trigger, this configuration is done by writing in
>> "slave_mode" device attribute.
>>
>> Since triggers could also be used by DAC or ADC their names are defined
>> in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will be able
>> to configure themselves in valid_trigger function
>>
>> Trigger have a "sampling_frequency" attribute which allow to configure
>> timer sampling frequency without using PWM interface
>>
>> version 5:
>> - simplify tables of triggers
>> - only create an IIO device when needed
>>
>> version 4:
>> - get triggers configuration from "reg" in DT
>> - add tables of triggers
>> - sampling frequency is enable/disable when writing in trigger
>>   sampling_frequency attribute
>> - no more use of interruptions
>>
>> version 3:
>> - change compatible to "st,stm32-timer-trigger"
>> - fix attributes access right
>> - use string instead of int for master_mode and slave_mode
>> - document device attributes in sysfs-bus-iio-timer-stm32
>>
>> version 2:
>> - keep only one compatible
>> - use st,input-triggers-names and st,output-triggers-names
>>   to know which triggers are accepted and/or create by the device
> Firstly, sorry it has taken me so long to get back to this.
>
> I'm still not keen on this use of iio_device elements just to act as
> glue between triggers.  I think we need to work out a more light weight
> way to do this.  As you are only using them for validation and to provide
> somewhere to hang the control attibutes off, there is nothing stopping us
> moving that over to the iio_trigger instead which would avoid the messy
> duality going on here.

I have add an iio_device because each hardware can generate multiple
triggers (up to 5: trgo, ch 1...4) and slave_mode attribute will impact all the
triggers of a device. For me it was making sense to centralize that in an
iio_device rather than having an attribute "shared" (from hardware
point of view)
on multiple triggers.
Since master_mode attribute is only used by trgo and not impact ch1...4
triggers I will move it to trigger instead of the iio_device.

I also wanted to be able to connect triggers on a iio_device as I
could do for an
ADC with a command like 'echo "tim1_trgo" > iio_deviceX/trigger/current_trigger'
If I change that to parent_trigger attribute it change this behavior
and I will have to
duplicated what is done in iio_trigger_write_current() to find and
validate triggers.

> I might still be missing something though!
>
> You would only I think need 3 attributes
>
> parrent_trigger
> and something like your master_mode and slave_mode attributes.
>
> The parrent_trigger would need some validation etc, but if we keep it
> within this driver initially that won't be hard to do. Checking the device
> parent matches will do most of it.
>
> Jonathan
>>
>> Signed-off-by: Benjamin Gaignard <[e-mail]>
>> ---
>>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
>>  drivers/iio/Kconfig                                |   2 +-
>>  drivers/iio/Makefile                               |   1 +
>>  drivers/iio/timer/Kconfig                          |  13 +
>>  drivers/iio/timer/Makefile                         |   1 +
>>  drivers/iio/timer/stm32-timer-trigger.c            | 466 +++++++++++++++++++++
>>  drivers/iio/trigger/Kconfig                        |   1 -
>>  include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
>>  8 files changed, 599 insertions(+), 2 deletions(-)
>>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>  create mode 100644 drivers/iio/timer/Kconfig
>>  create mode 100644 drivers/iio/timer/Makefile
>>  create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
>>  create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>> new file mode 100644
>> index 0000000..26583dd
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>> @@ -0,0 +1,55 @@
>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode_available
>> +KernelVersion:       4.10
>> +Contact:     [e-mail]
>> +Description:
>> +             Reading returns the list possible master modes which are:
>> +             - "reset"     : The UG bit from the TIMx_EGR register is used as trigger output (TRGO).
>> +             - "enable"    : The Counter Enable signal CNT_EN is used as trigger output.
>> +             - "update"    : The update event is selected as trigger output.
>> +                             For instance a master timer can then be used as a prescaler for a slave timer.
>> +             - "compare_pulse" : The trigger output send a positive pulse when the CC1IF flag is to be set.
>> +             - "OC1REF"    : OC1REF signal is used as trigger output.
>> +             - "OC2REF"    : OC2REF signal is used as trigger output.
>> +             - "OC3REF"    : OC3REF signal is used as trigger output.
>> +             - "OC4REF"    : OC4REF signal is used as trigger output.
>> +
>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode
>> +KernelVersion:       4.10
>> +Contact:     [e-mail]
>> +Description:
>> +             Reading returns the current master modes.
>> +             Writing set the master mode
>> +
>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode_available
>> +KernelVersion:       4.10
>> +Contact:     [e-mail]
>> +Description:
>> +             Reading returns the list possible slave modes which are:
>> +             - "disabled"  : The prescaler is clocked directly by the internal clock.
>> +             - "encoder_1" : Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
>> +             - "encoder_2" : Counter counts up/down on TI1FP2 edge depending on TI2FP1 level.
>> +             - "encoder_3" : Counter counts up/down on both TI1FP1 and TI2FP2 edges depending
>> +                             on the level of the other input.
>> +             - "reset"     : Rising edge of the selected trigger input reinitializes the counter
>> +                             and generates an update of the registers.
>> +             - "gated"     : The counter clock is enabled when the trigger input is high.
>> +                             The counter stops (but is not reset) as soon as the trigger becomes low.
>> +                             Both start and stop of the counter are controlled.
>> +             - "trigger"   : The counter starts at a rising edge of the trigger TRGI (but it is not
>> +                             reset). Only the start of the counter is controlled.
>> +             - "external_clock": Rising edges of the selected trigger (TRGI) clock the counter.
>> +
>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode
>> +KernelVersion:       4.10
>> +Contact:     [e-mail]
>> +Description:
>> +             Reading returns the current slave mode.
>> +             Writing set the slave mode
>> +
>> +What:                /sys/bus/iio/devices/triggerX/sampling_frequency
>> +KernelVersion:       4.10
>> +Contact:     [e-mail]
>> +Description:
>> +             Reading returns the current sampling frequency.
>> +             Writing an value different of 0 set and start sampling.
>> +             Writing 0 stop sampling.
>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>> index 6743b18..2de2a80 100644
>> --- a/drivers/iio/Kconfig
>> +++ b/drivers/iio/Kconfig
>> @@ -90,5 +90,5 @@ source "drivers/iio/potentiometer/Kconfig"
>>  source "drivers/iio/pressure/Kconfig"
>>  source "drivers/iio/proximity/Kconfig"
>>  source "drivers/iio/temperature/Kconfig"
>> -
>> +source "drivers/iio/timer/Kconfig"
>>  endif # IIO
>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>> index 87e4c43..b797c08 100644
>> --- a/drivers/iio/Makefile
>> +++ b/drivers/iio/Makefile
>> @@ -32,4 +32,5 @@ obj-y += potentiometer/
>>  obj-y += pressure/
>>  obj-y += proximity/
>>  obj-y += temperature/
>> +obj-y += timer/
>>  obj-y += trigger/
>> diff --git a/drivers/iio/timer/Kconfig b/drivers/iio/timer/Kconfig
>> new file mode 100644
>> index 0000000..e3c21f2
>> --- /dev/null
>> +++ b/drivers/iio/timer/Kconfig
>> @@ -0,0 +1,13 @@
>> +#
>> +# Timers drivers
>> +
>> +menu "Timers"
>> +
>> +config IIO_STM32_TIMER_TRIGGER
>> +     tristate "STM32 Timer Trigger"
>> +     depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) || COMPILE_TEST
>> +     select IIO_TRIGGERED_EVENT
>> +     help
>> +       Select this option to enable STM32 Timer Trigger
>> +
>> +endmenu
>> diff --git a/drivers/iio/timer/Makefile b/drivers/iio/timer/Makefile
>> new file mode 100644
>> index 0000000..4ad95ec9
>> --- /dev/null
>> +++ b/drivers/iio/timer/Makefile
>> @@ -0,0 +1 @@
>> +obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
>> diff --git a/drivers/iio/timer/stm32-timer-trigger.c b/drivers/iio/timer/stm32-timer-trigger.c
>> new file mode 100644
>> index 0000000..8d16e8f
>> --- /dev/null
>> +++ b/drivers/iio/timer/stm32-timer-trigger.c
>> @@ -0,0 +1,466 @@
>> +/*
>> + * Copyright (C) STMicroelectronics 2016
>> + *
>> + * Author: Benjamin Gaignard <[e-mail]>
>> + *
>> + * License terms:  GNU General Public License (GPL), version 2
>> + */
>> +
>> +#include <linux/iio/iio.h>
>> +#include <linux/iio/sysfs.h>
>> +#include <linux/iio/timer/stm32-timer-trigger.h>
>> +#include <linux/iio/trigger.h>
>> +#include <linux/iio/triggered_event.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/mfd/stm32-timers.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define MAX_TRIGGERS 6
>> +#define MAX_VALIDS 5
>> +
>> +/* List the triggers created by each timer */
>> +static const void *triggers_table[][MAX_TRIGGERS] = {
>> +     { TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
>> +     { TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
>> +     { TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
>> +     { TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
>> +     { TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
>> +     { TIM6_TRGO,},
>> +     { TIM7_TRGO,},
>> +     { TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
>> +     { TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
>> +     { TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
>> +};
>> +
>> +/* List the triggers accepted by each timer */
>> +static const void *valids_table[][MAX_VALIDS] = {
>> +     { TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
>> +     { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
>> +     { TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
>> +     { TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
>> +     { TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
>> +     { }, /* timer 6 */
>> +     { }, /* timer 7 */
>> +     { TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
>> +     { TIM2_TRGO, TIM3_TRGO,},
>> +     { TIM4_TRGO, TIM5_TRGO,},
>> +};
>> +
>> +struct stm32_timer_trigger {
>> +     struct device *dev;
>> +     struct regmap *regmap;
>> +     struct clk *clk;
>> +     u32 max_arr;
>> +     const void *triggers;
>> +     const void *valids;
>> +};
>> +
>> +static int stm32_timer_start(struct stm32_timer_trigger *priv,
>> +                          unsigned int frequency)
>> +{
>> +     unsigned long long prd, div;
>> +     int prescaler = 0;
>> +     u32 ccer, cr1;
>> +
>> +     /* Period and prescaler values depends of clock rate */
>> +     div = (unsigned long long)clk_get_rate(priv->clk);
>> +
>> +     do_div(div, frequency);
>> +
>> +     prd = div;
>> +
>> +     /*
>> +      * Increase prescaler value until we get a result that fit
>> +      * with auto reload register maximum value.
>> +      */
>> +     while (div > priv->max_arr) {
>> +             prescaler++;
>> +             div = prd;
>> +             do_div(div, (prescaler + 1));
>> +     }
>> +     prd = div;
>> +
>> +     if (prescaler > MAX_TIM_PSC) {
>> +             dev_err(priv->dev, "prescaler exceeds the maximum value\n");
>> +             return -EINVAL;
>> +     }
>> +
>> +     /* Check if nobody else use the timer */
>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>> +     if (ccer & TIM_CCER_CCXE)
>> +             return -EBUSY;
>> +
>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>> +     if (!(cr1 & TIM_CR1_CEN))
>> +             clk_enable(priv->clk);
>> +
>> +     regmap_write(priv->regmap, TIM_PSC, prescaler);
>> +     regmap_write(priv->regmap, TIM_ARR, prd - 1);
>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
>> +
>> +     /* Force master mode to update mode */
>> +     regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
>> +
>> +     /* Make sure that registers are updated */
>> +     regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
>> +
>> +     /* Enable controller */
>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
>> +
>> +     return 0;
>> +}
>> +
>> +static void stm32_timer_stop(struct stm32_timer_trigger *priv)
>> +{
>> +     u32 ccer, cr1;
>> +
>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>> +     if (ccer & TIM_CCER_CCXE)
>> +             return;
>> +
>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>> +     if (cr1 & TIM_CR1_CEN)
>> +             clk_disable(priv->clk);
>> +
>> +     /* Stop timer */
>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
>> +     regmap_write(priv->regmap, TIM_PSC, 0);
>> +     regmap_write(priv->regmap, TIM_ARR, 0);
>> +}
>> +
>> +static ssize_t stm32_tt_store_frequency(struct device *dev,
>> +                                     struct device_attribute *attr,
>> +                                     const char *buf, size_t len)
>> +{
>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>> +     struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>> +     unsigned int freq;
>> +     int ret;
>> +
>> +     ret = kstrtouint(buf, 10, &freq);
>> +     if (ret)
>> +             return ret;
>> +
>> +     if (freq == 0) {
>> +             stm32_timer_stop(priv);
>> +     } else {
>> +             ret = stm32_timer_start(priv, freq);
>> +             if (ret)
>> +                     return ret;
>> +     }
>> +
>> +     return len;
>> +}
>> +
>> +static ssize_t stm32_tt_read_frequency(struct device *dev,
>> +                                    struct device_attribute *attr, char *buf)
>> +{
>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>> +     struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>> +     u32 psc, arr, cr1;
>> +     unsigned long long freq = 0;
>> +
>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>> +     regmap_read(priv->regmap, TIM_PSC, &psc);
>> +     regmap_read(priv->regmap, TIM_ARR, &arr);
>> +
>> +     if (psc && arr && (cr1 & TIM_CR1_CEN)) {
>> +             freq = (unsigned long long)clk_get_rate(priv->clk);
>> +             do_div(freq, psc);
>> +             do_div(freq, arr);
>> +     }
>> +
>> +     return sprintf(buf, "%d\n", (unsigned int)freq);
>> +}
>> +
>> +static IIO_DEV_ATTR_SAMP_FREQ(0660,
>> +                           stm32_tt_read_frequency,
>> +                           stm32_tt_store_frequency);
>> +
>> +static struct attribute *stm32_trigger_attrs[] = {
>> +     &iio_dev_attr_sampling_frequency.dev_attr.attr,
>> +     NULL,
>> +};
>> +
>> +static const struct attribute_group stm32_trigger_attr_group = {
>> +     .attrs = stm32_trigger_attrs,
>> +};
>> +
>> +static const struct attribute_group *stm32_trigger_attr_groups[] = {
>> +     &stm32_trigger_attr_group,
>> +     NULL,
>> +};
>> +
>> +static char *master_mode_table[] = {
>> +     "reset",
>> +     "enable",
>> +     "update",
>> +     "compare_pulse",
>> +     "OC1REF",
>> +     "OC2REF",
>> +     "OC3REF",
>> +     "OC4REF"
>> +};
>> +
>> +static ssize_t stm32_tt_show_master_mode(struct device *dev,
>> +                                      struct device_attribute *attr,
>> +                                      char *buf)
>> +{
>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     u32 cr2;
>> +
>> +     regmap_read(priv->regmap, TIM_CR2, &cr2);
>> +     cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
>> +
>> +     return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
>> +}
>> +
>> +static ssize_t stm32_tt_store_master_mode(struct device *dev,
>> +                                       struct device_attribute *attr,
>> +                                       const char *buf, size_t len)
>> +{
>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     int i;
>> +
>> +     for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
>> +             if (!strncmp(master_mode_table[i], buf,
>> +                          strlen(master_mode_table[i]))) {
>> +                     regmap_update_bits(priv->regmap, TIM_CR2,
>> +                                        TIM_CR2_MMS, i << TIM_CR2_MMS_SHIFT);
>> +                     return len;
>> +             }
>> +     }
>> +
>> +     return -EINVAL;
>> +}
>> +
>> +static IIO_CONST_ATTR(master_mode_available,
>> +     "reset enable update compare_pulse OC1REF OC2REF OC3REF OC4REF");
>> +
>> +static IIO_DEVICE_ATTR(master_mode, 0660,
>> +                    stm32_tt_show_master_mode,
>> +                    stm32_tt_store_master_mode,
>> +                    0);
>> +
>> +static char *slave_mode_table[] = {
>> +     "disabled",
>> +     "encoder_1",
>> +     "encoder_2",
>> +     "encoder_3",
>> +     "reset",
>> +     "gated",
>> +     "trigger",
>> +     "external_clock",
>> +};
>> +
>> +static ssize_t stm32_tt_show_slave_mode(struct device *dev,
>> +                                     struct device_attribute *attr,
>> +                                     char *buf)
>> +{
>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     u32 smcr;
>> +
>> +     regmap_read(priv->regmap, TIM_SMCR, &smcr);
>> +     smcr &= TIM_SMCR_SMS;
>> +
>> +     return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
>> +}
>> +
>> +static ssize_t stm32_tt_store_slave_mode(struct device *dev,
>> +                                      struct device_attribute *attr,
>> +                                      const char *buf, size_t len)
>> +{
>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     int i;
>> +
>> +     for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
>> +             if (!strncmp(slave_mode_table[i], buf,
>> +                          strlen(slave_mode_table[i]))) {
>> +                     regmap_update_bits(priv->regmap,
>> +                                        TIM_SMCR, TIM_SMCR_SMS, i);
>> +                     return len;
>> +             }
>> +     }
>> +
>> +     return -EINVAL;
>> +}
>> +
>> +static IIO_CONST_ATTR(slave_mode_available,
>> +"disabled encoder_1 encoder_2 encoder_3 reset gated trigger external_clock");
>> +
>> +static IIO_DEVICE_ATTR(slave_mode, 0660,
>> +                    stm32_tt_show_slave_mode,
>> +                    stm32_tt_store_slave_mode,
>> +                    0);
>> +
>> +static struct attribute *stm32_timer_attrs[] = {
>> +     &iio_dev_attr_master_mode.dev_attr.attr,
>> +     &iio_const_attr_master_mode_available.dev_attr.attr,
>> +     &iio_dev_attr_slave_mode.dev_attr.attr,
>> +     &iio_const_attr_slave_mode_available.dev_attr.attr,
>> +     NULL,
>> +};
>> +
>> +static const struct attribute_group stm32_timer_attr_group = {
>> +     .attrs = stm32_timer_attrs,
>> +};
>> +
>> +static const struct iio_trigger_ops timer_trigger_ops = {
>> +     .owner = THIS_MODULE,
>> +};
>> +
>> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
>> +{
>> +     int ret;
>> +     const char * const *cur = priv->triggers;
>> +
>> +     while (cur && *cur) {
>> +             struct iio_trigger *trig;
>> +
>> +             trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur);
>> +             if  (!trig)
>> +                     return -ENOMEM;
>> +
>> +             trig->dev.parent = priv->dev->parent;
>> +             trig->ops = &timer_trigger_ops;
>> +             trig->dev.groups = stm32_trigger_attr_groups;
>> +             iio_trigger_set_drvdata(trig, priv);
>> +
>> +             ret = devm_iio_trigger_register(priv->dev, trig);
>> +             if (ret)
>> +                     return ret;
>> +             cur++;
>> +     }
>> +
>> +     return 0;
>> +}
>> +
>> +/**
>> + * is_stm32_timer_trigger
>> + * @trig: trigger to be checked
>> + *
>> + * return true if the trigger is a valid stm32 iio timer trigger
>> + * either return false
>> + */
>> +bool is_stm32_timer_trigger(struct iio_trigger *trig)
>> +{
>> +     return (trig->ops == &timer_trigger_ops);
>> +}
>> +EXPORT_SYMBOL(is_stm32_timer_trigger);
>> +
>> +static int stm32_validate_trigger(struct iio_dev *indio_dev,
>> +                               struct iio_trigger *trig)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     const char * const *cur = priv->valids;
>> +     unsigned int i = 0;
>> +
>> +     if (!is_stm32_timer_trigger(trig))
>> +             return -EINVAL;
>> +
>> +     while (cur && *cur) {
>> +             if (!strncmp(trig->name, *cur, strlen(trig->name))) {
>> +                     regmap_update_bits(priv->regmap,
>> +                                        TIM_SMCR, TIM_SMCR_TS,
>> +                                        i << TIM_SMCR_TS_SHIFT);
>> +                     return 0;
>> +             }
>> +             cur++;
>> +             i++;
>> +     }
>> +
>> +     return -EINVAL;
>> +}
>> +
>> +static const struct iio_info stm32_trigger_info = {
>> +     .driver_module = THIS_MODULE,
>> +     .validate_trigger = stm32_validate_trigger,
>> +     .attrs = &stm32_timer_attr_group,
>> +};
>> +
>> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
>> +{
>> +     struct iio_dev *indio_dev;
>> +     int ret;
>> +
>> +     indio_dev = devm_iio_device_alloc(dev,
>> +                                       sizeof(struct stm32_timer_trigger));
>> +     if (!indio_dev)
>> +             return NULL;
>> +
>> +     indio_dev->name = dev_name(dev);
>> +     indio_dev->dev.parent = dev;
>> +     indio_dev->info = &stm32_trigger_info;
>> +     indio_dev->modes = INDIO_EVENT_TRIGGERED;
>> +     indio_dev->num_channels = 0;
>> +     indio_dev->dev.of_node = dev->of_node;
>> +
>> +     ret = devm_iio_device_register(dev, indio_dev);
>> +     if (ret)
>> +             return NULL;
>> +
>> +     return iio_priv(indio_dev);
>> +}
>> +
>> +static int stm32_timer_trigger_probe(struct platform_device *pdev)
>> +{
>> +     struct device *dev = &pdev->dev;
>> +     struct stm32_timer_trigger *priv;
>> +     struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
>> +     unsigned int index;
>> +     int ret;
>> +
>> +     if (of_property_read_u32(dev->of_node, "reg", &index))
>> +             return -EINVAL;
>> +
>> +     if (index >= ARRAY_SIZE(triggers_table))
>> +             return -EINVAL;
>> +
>> +     /* Create an IIO device only if we have triggers to be validated */
>> +     if (*valids_table[index])
>> +             priv = stm32_setup_iio_device(dev);
>
> I still don't like this. Really feels like we shouldn't be creating an
> iio device with all the bagage that carries just to allow us to do the
> trigger trees.  We ought to have a much more light weight solution for this
> functionality - we aren't typically even using the interrupt tree stuff
> that the triggers for devices are all really about.
>
> A simpler approach of allowing each trigger the option of a parent seems like
> it would be cleaner.  Could be done entirely within this driver in the first
> instance.  Basically it would just look like your master and slave attributes
> but have those under triggerX not iio:deviceX.
>
> We can work out how to make it more generic later - including perhaps the
> option to trigger from triggers outside this driver, using some parallel
> infrastructure to the device triggering.
>
>
>> +     else
>> +             priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> +
>> +     if (!priv)
>> +             return -ENOMEM;
>> +
>> +     priv->dev = dev;
>> +     priv->regmap = ddata->regmap;
>> +     priv->clk = ddata->clk;
>> +     priv->max_arr = ddata->max_arr;
>> +     priv->triggers = triggers_table[index];
>> +     priv->valids = valids_table[index];
>> +
>> +     ret = stm32_setup_iio_triggers(priv);
>> +     if (ret)
>> +             return ret;
>> +
>> +     platform_set_drvdata(pdev, priv);
>> +
>> +     return 0;
>> +}
>> +
>> +static const struct of_device_id stm32_trig_of_match[] = {
>> +     { .compatible = "st,stm32-timer-trigger", },
>> +     { /* end node */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
>> +
>> +static struct platform_driver stm32_timer_trigger_driver = {
>> +     .probe = stm32_timer_trigger_probe,
>> +     .driver = {
>> +             .name = "stm32-timer-trigger",
>> +             .of_match_table = stm32_trig_of_match,
>> +     },
>> +};
>> +module_platform_driver(stm32_timer_trigger_driver);
>> +
>> +MODULE_ALIAS("platform: stm32-timer-trigger");
>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger driver");
>> +MODULE_LICENSE("GPL v2");
>> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
>> index 809b2e7..f2af4fe 100644
>> --- a/drivers/iio/trigger/Kconfig
>> +++ b/drivers/iio/trigger/Kconfig
>> @@ -46,5 +46,4 @@ config IIO_SYSFS_TRIGGER
>>
>>         To compile this driver as a module, choose M here: the
>>         module will be called iio-trig-sysfs.
>> -
> Clean this up.

ok

>>  endmenu
>> diff --git a/include/linux/iio/timer/stm32-timer-trigger.h b/include/linux/iio/timer/stm32-timer-trigger.h
>> new file mode 100644
>> index 0000000..55535ae
>> --- /dev/null
>> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
>> @@ -0,0 +1,62 @@
>> +/*
>> + * Copyright (C) STMicroelectronics 2016
>> + *
>> + * Author: Benjamin Gaignard <[e-mail]>
>> + *
>> + * License terms:  GNU General Public License (GPL), version 2
>> + */
>> +
>> +#ifndef _STM32_TIMER_TRIGGER_H_
>> +#define _STM32_TIMER_TRIGGER_H_
>> +
>> +#define TIM1_TRGO    "tim1_trgo"
>> +#define TIM1_CH1     "tim1_ch1"
>> +#define TIM1_CH2     "tim1_ch2"
>> +#define TIM1_CH3     "tim1_ch3"
>> +#define TIM1_CH4     "tim1_ch4"
>> +
>> +#define TIM2_TRGO    "tim2_trgo"
>> +#define TIM2_CH1     "tim2_ch1"
>> +#define TIM2_CH2     "tim2_ch2"
>> +#define TIM2_CH3     "tim2_ch3"
>> +#define TIM2_CH4     "tim2_ch4"
>> +
>> +#define TIM3_TRGO    "tim3_trgo"
>> +#define TIM3_CH1     "tim3_ch1"
>> +#define TIM3_CH2     "tim3_ch2"
>> +#define TIM3_CH3     "tim3_ch3"
>> +#define TIM3_CH4     "tim3_ch4"
>> +
>> +#define TIM4_TRGO    "tim4_trgo"
>> +#define TIM4_CH1     "tim4_ch1"
>> +#define TIM4_CH2     "tim4_ch2"
>> +#define TIM4_CH3     "tim4_ch3"
>> +#define TIM4_CH4     "tim4_ch4"
>> +
>> +#define TIM5_TRGO    "tim5_trgo"
>> +#define TIM5_CH1     "tim5_ch1"
>> +#define TIM5_CH2     "tim5_ch2"
>> +#define TIM5_CH3     "tim5_ch3"
>> +#define TIM5_CH4     "tim5_ch4"
>> +
>> +#define TIM6_TRGO    "tim6_trgo"
>> +
>> +#define TIM7_TRGO    "tim7_trgo"
>> +
>> +#define TIM8_TRGO    "tim8_trgo"
>> +#define TIM8_CH1     "tim8_ch1"
>> +#define TIM8_CH2     "tim8_ch2"
>> +#define TIM8_CH3     "tim8_ch3"
>> +#define TIM8_CH4     "tim8_ch4"
>> +
>> +#define TIM9_TRGO    "tim9_trgo"
>> +#define TIM9_CH1     "tim9_ch1"
>> +#define TIM9_CH2     "tim9_ch2"
>> +
>> +#define TIM12_TRGO   "tim12_trgo"
>> +#define TIM12_CH1    "tim12_ch1"
>> +#define TIM12_CH2    "tim12_ch2"
>> +
>> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
>> +
>> +#endif
>>
>

Jonathan Cameron Jan. 2, 2017, 6:22 p.m. UTC | #3

On 02/01/17 08:46, Benjamin Gaignard wrote:
> 2016-12-30 22:12 GMT+01:00 Jonathan Cameron <[e-mail]>:
>> On 09/12/16 14:15, Benjamin Gaignard wrote:
>>> Timers IPs can be used to generate triggers for other IPs like
>>> DAC, ADC or other timers.
>>> Each trigger may result of timer internals signals like counter enable,
>>> reset or edge, this configuration could be done through "master_mode"
>>> device attribute.
>>>
>>> A timer device could be triggered by other timers, we use the trigger
>>> name and is_stm32_iio_timer_trigger() function to distinguish them
>>> and configure IP input switch.
>>>
>>> Timer may also decide on which event (edge, level) they could
>>> be activated by a trigger, this configuration is done by writing in
>>> "slave_mode" device attribute.
>>>
>>> Since triggers could also be used by DAC or ADC their names are defined
>>> in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will be able
>>> to configure themselves in valid_trigger function
>>>
>>> Trigger have a "sampling_frequency" attribute which allow to configure
>>> timer sampling frequency without using PWM interface
>>>
>>> version 5:
>>> - simplify tables of triggers
>>> - only create an IIO device when needed
>>>
>>> version 4:
>>> - get triggers configuration from "reg" in DT
>>> - add tables of triggers
>>> - sampling frequency is enable/disable when writing in trigger
>>>   sampling_frequency attribute
>>> - no more use of interruptions
>>>
>>> version 3:
>>> - change compatible to "st,stm32-timer-trigger"
>>> - fix attributes access right
>>> - use string instead of int for master_mode and slave_mode
>>> - document device attributes in sysfs-bus-iio-timer-stm32
>>>
>>> version 2:
>>> - keep only one compatible
>>> - use st,input-triggers-names and st,output-triggers-names
>>>   to know which triggers are accepted and/or create by the device
>> Firstly, sorry it has taken me so long to get back to this.
>>
>> I'm still not keen on this use of iio_device elements just to act as
>> glue between triggers.  I think we need to work out a more light weight
>> way to do this.  As you are only using them for validation and to provide
>> somewhere to hang the control attibutes off, there is nothing stopping us
>> moving that over to the iio_trigger instead which would avoid the messy
>> duality going on here.
> 
> I have add an iio_device because each hardware can generate multiple
> triggers (up to 5: trgo, ch 1...4) and slave_mode attribute will impact all the
> triggers of a device. For me it was making sense to centralize that in an
> iio_device rather than having an attribute "shared" (from hardware
> point of view)
> on multiple triggers.
> Since master_mode attribute is only used by trgo and not impact ch1...4
> triggers I will move it to trigger instead of the iio_device.
> 
> I also wanted to be able to connect triggers on a iio_device as I
> could do for an
> ADC with a command like 'echo "tim1_trgo" > iio_deviceX/trigger/current_trigger'
This is interesting, but with a bit of refactoring I would think it would
be possible to share some of that code thus allowing non IIO devices to
bind to triggers.  Ultimately I want to be able to bind a trigger to
a trigger - I appreciate here the topology is more limited than that
so some complexity comes in.

My gut feeling is that representing that topology explicitly is hard
to do in a remotely general way, but lets try it and see.
We run into this sort of interdependency issue between different bits of
the hardware all the time.  Setting a value somewhere effects the configuration
elsewhere - often the best plan is to just let that happen and leave it up to
userspace to check for changes if it cares.

> If I change that to parent_trigger attribute it change this behavior
> and I will have to
> duplicated what is done in iio_trigger_write_current() to find and
> validate triggers.
I get the reasoning, but we still end up with something represented
by an IIO device that isn't providing any channels at all. It's simply
using some of the infrastructure.  To my mind it is 'something else'
and should be represented as such.  I have no problem at all with
you registering additional elements in /sysfs/bus/iio/ to represent
these shared elements - we already have drivers that do that to
provide some centralized infrastructure (e.g. the sysfs-trigger)

I'm worried about the scope spread we get for an IIO device otherwise.
They serve a well defined purpose at the moment, and that isn't what
is happening here.

So my gut feeling is we are better deliberately not representing the
inter dependence and claiming all triggers we are creating are
independent.  That way we can have a nice generic infrastructure
that will work in all cases (be it pushing the sanity checking to
userspace).

So each trigger has direct access to what controls it.  Changing anything
can effect other triggers in weird ways.

I'm finding it hard to see anything else generalizing sufficiently
as we'll always get cases where we can't represent the topology without
diving into the complexity of something like the media controller
framework.

Jonathan
> 
>> I might still be missing something though!
>>
>> You would only I think need 3 attributes
>>
>> parrent_trigger
>> and something like your master_mode and slave_mode attributes.
>>
>> The parrent_trigger would need some validation etc, but if we keep it
>> within this driver initially that won't be hard to do. Checking the device
>> parent matches will do most of it.
>>
>> Jonathan
>>>
>>> Signed-off-by: Benjamin Gaignard <[e-mail]>
>>> ---
>>>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
>>>  drivers/iio/Kconfig                                |   2 +-
>>>  drivers/iio/Makefile                               |   1 +
>>>  drivers/iio/timer/Kconfig                          |  13 +
>>>  drivers/iio/timer/Makefile                         |   1 +
>>>  drivers/iio/timer/stm32-timer-trigger.c            | 466 +++++++++++++++++++++
>>>  drivers/iio/trigger/Kconfig                        |   1 -
>>>  include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
>>>  8 files changed, 599 insertions(+), 2 deletions(-)
>>>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>  create mode 100644 drivers/iio/timer/Kconfig
>>>  create mode 100644 drivers/iio/timer/Makefile
>>>  create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
>>>  create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>> new file mode 100644
>>> index 0000000..26583dd
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>> @@ -0,0 +1,55 @@
>>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode_available
>>> +KernelVersion:       4.10
>>> +Contact:     [e-mail]
>>> +Description:
>>> +             Reading returns the list possible master modes which are:
>>> +             - "reset"     : The UG bit from the TIMx_EGR register is used as trigger output (TRGO).
>>> +             - "enable"    : The Counter Enable signal CNT_EN is used as trigger output.
>>> +             - "update"    : The update event is selected as trigger output.
>>> +                             For instance a master timer can then be used as a prescaler for a slave timer.
>>> +             - "compare_pulse" : The trigger output send a positive pulse when the CC1IF flag is to be set.
>>> +             - "OC1REF"    : OC1REF signal is used as trigger output.
>>> +             - "OC2REF"    : OC2REF signal is used as trigger output.
>>> +             - "OC3REF"    : OC3REF signal is used as trigger output.
>>> +             - "OC4REF"    : OC4REF signal is used as trigger output.
>>> +
>>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode
>>> +KernelVersion:       4.10
>>> +Contact:     [e-mail]
>>> +Description:
>>> +             Reading returns the current master modes.
>>> +             Writing set the master mode
>>> +
>>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode_available
>>> +KernelVersion:       4.10
>>> +Contact:     [e-mail]
>>> +Description:
>>> +             Reading returns the list possible slave modes which are:
>>> +             - "disabled"  : The prescaler is clocked directly by the internal clock.
>>> +             - "encoder_1" : Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
>>> +             - "encoder_2" : Counter counts up/down on TI1FP2 edge depending on TI2FP1 level.
>>> +             - "encoder_3" : Counter counts up/down on both TI1FP1 and TI2FP2 edges depending
>>> +                             on the level of the other input.
>>> +             - "reset"     : Rising edge of the selected trigger input reinitializes the counter
>>> +                             and generates an update of the registers.
>>> +             - "gated"     : The counter clock is enabled when the trigger input is high.
>>> +                             The counter stops (but is not reset) as soon as the trigger becomes low.
>>> +                             Both start and stop of the counter are controlled.
>>> +             - "trigger"   : The counter starts at a rising edge of the trigger TRGI (but it is not
>>> +                             reset). Only the start of the counter is controlled.
>>> +             - "external_clock": Rising edges of the selected trigger (TRGI) clock the counter.
>>> +
>>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode
>>> +KernelVersion:       4.10
>>> +Contact:     [e-mail]
>>> +Description:
>>> +             Reading returns the current slave mode.
>>> +             Writing set the slave mode
>>> +
>>> +What:                /sys/bus/iio/devices/triggerX/sampling_frequency
>>> +KernelVersion:       4.10
>>> +Contact:     [e-mail]
>>> +Description:
>>> +             Reading returns the current sampling frequency.
>>> +             Writing an value different of 0 set and start sampling.
>>> +             Writing 0 stop sampling.
>>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>>> index 6743b18..2de2a80 100644
>>> --- a/drivers/iio/Kconfig
>>> +++ b/drivers/iio/Kconfig
>>> @@ -90,5 +90,5 @@ source "drivers/iio/potentiometer/Kconfig"
>>>  source "drivers/iio/pressure/Kconfig"
>>>  source "drivers/iio/proximity/Kconfig"
>>>  source "drivers/iio/temperature/Kconfig"
>>> -
>>> +source "drivers/iio/timer/Kconfig"
>>>  endif # IIO
>>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>>> index 87e4c43..b797c08 100644
>>> --- a/drivers/iio/Makefile
>>> +++ b/drivers/iio/Makefile
>>> @@ -32,4 +32,5 @@ obj-y += potentiometer/
>>>  obj-y += pressure/
>>>  obj-y += proximity/
>>>  obj-y += temperature/
>>> +obj-y += timer/
>>>  obj-y += trigger/
>>> diff --git a/drivers/iio/timer/Kconfig b/drivers/iio/timer/Kconfig
>>> new file mode 100644
>>> index 0000000..e3c21f2
>>> --- /dev/null
>>> +++ b/drivers/iio/timer/Kconfig
>>> @@ -0,0 +1,13 @@
>>> +#
>>> +# Timers drivers
>>> +
>>> +menu "Timers"
>>> +
>>> +config IIO_STM32_TIMER_TRIGGER
>>> +     tristate "STM32 Timer Trigger"
>>> +     depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) || COMPILE_TEST
>>> +     select IIO_TRIGGERED_EVENT
>>> +     help
>>> +       Select this option to enable STM32 Timer Trigger
>>> +
>>> +endmenu
>>> diff --git a/drivers/iio/timer/Makefile b/drivers/iio/timer/Makefile
>>> new file mode 100644
>>> index 0000000..4ad95ec9
>>> --- /dev/null
>>> +++ b/drivers/iio/timer/Makefile
>>> @@ -0,0 +1 @@
>>> +obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
>>> diff --git a/drivers/iio/timer/stm32-timer-trigger.c b/drivers/iio/timer/stm32-timer-trigger.c
>>> new file mode 100644
>>> index 0000000..8d16e8f
>>> --- /dev/null
>>> +++ b/drivers/iio/timer/stm32-timer-trigger.c
>>> @@ -0,0 +1,466 @@
>>> +/*
>>> + * Copyright (C) STMicroelectronics 2016
>>> + *
>>> + * Author: Benjamin Gaignard <[e-mail]>
>>> + *
>>> + * License terms:  GNU General Public License (GPL), version 2
>>> + */
>>> +
>>> +#include <linux/iio/iio.h>
>>> +#include <linux/iio/sysfs.h>
>>> +#include <linux/iio/timer/stm32-timer-trigger.h>
>>> +#include <linux/iio/trigger.h>
>>> +#include <linux/iio/triggered_event.h>
>>> +#include <linux/interrupt.h>
>>> +#include <linux/mfd/stm32-timers.h>
>>> +#include <linux/module.h>
>>> +#include <linux/platform_device.h>
>>> +
>>> +#define MAX_TRIGGERS 6
>>> +#define MAX_VALIDS 5
>>> +
>>> +/* List the triggers created by each timer */
>>> +static const void *triggers_table[][MAX_TRIGGERS] = {
>>> +     { TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
>>> +     { TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
>>> +     { TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
>>> +     { TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
>>> +     { TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
>>> +     { TIM6_TRGO,},
>>> +     { TIM7_TRGO,},
>>> +     { TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
>>> +     { TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
>>> +     { TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
>>> +};
>>> +
>>> +/* List the triggers accepted by each timer */
>>> +static const void *valids_table[][MAX_VALIDS] = {
>>> +     { TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
>>> +     { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
>>> +     { TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
>>> +     { TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
>>> +     { TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
>>> +     { }, /* timer 6 */
>>> +     { }, /* timer 7 */
>>> +     { TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
>>> +     { TIM2_TRGO, TIM3_TRGO,},
>>> +     { TIM4_TRGO, TIM5_TRGO,},
>>> +};
>>> +
>>> +struct stm32_timer_trigger {
>>> +     struct device *dev;
>>> +     struct regmap *regmap;
>>> +     struct clk *clk;
>>> +     u32 max_arr;
>>> +     const void *triggers;
>>> +     const void *valids;
>>> +};
>>> +
>>> +static int stm32_timer_start(struct stm32_timer_trigger *priv,
>>> +                          unsigned int frequency)
>>> +{
>>> +     unsigned long long prd, div;
>>> +     int prescaler = 0;
>>> +     u32 ccer, cr1;
>>> +
>>> +     /* Period and prescaler values depends of clock rate */
>>> +     div = (unsigned long long)clk_get_rate(priv->clk);
>>> +
>>> +     do_div(div, frequency);
>>> +
>>> +     prd = div;
>>> +
>>> +     /*
>>> +      * Increase prescaler value until we get a result that fit
>>> +      * with auto reload register maximum value.
>>> +      */
>>> +     while (div > priv->max_arr) {
>>> +             prescaler++;
>>> +             div = prd;
>>> +             do_div(div, (prescaler + 1));
>>> +     }
>>> +     prd = div;
>>> +
>>> +     if (prescaler > MAX_TIM_PSC) {
>>> +             dev_err(priv->dev, "prescaler exceeds the maximum value\n");
>>> +             return -EINVAL;
>>> +     }
>>> +
>>> +     /* Check if nobody else use the timer */
>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>> +     if (ccer & TIM_CCER_CCXE)
>>> +             return -EBUSY;
>>> +
>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>> +     if (!(cr1 & TIM_CR1_CEN))
>>> +             clk_enable(priv->clk);
>>> +
>>> +     regmap_write(priv->regmap, TIM_PSC, prescaler);
>>> +     regmap_write(priv->regmap, TIM_ARR, prd - 1);
>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
>>> +
>>> +     /* Force master mode to update mode */
>>> +     regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
>>> +
>>> +     /* Make sure that registers are updated */
>>> +     regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
>>> +
>>> +     /* Enable controller */
>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static void stm32_timer_stop(struct stm32_timer_trigger *priv)
>>> +{
>>> +     u32 ccer, cr1;
>>> +
>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>> +     if (ccer & TIM_CCER_CCXE)
>>> +             return;
>>> +
>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>> +     if (cr1 & TIM_CR1_CEN)
>>> +             clk_disable(priv->clk);
>>> +
>>> +     /* Stop timer */
>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
>>> +     regmap_write(priv->regmap, TIM_PSC, 0);
>>> +     regmap_write(priv->regmap, TIM_ARR, 0);
>>> +}
>>> +
>>> +static ssize_t stm32_tt_store_frequency(struct device *dev,
>>> +                                     struct device_attribute *attr,
>>> +                                     const char *buf, size_t len)
>>> +{
>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>> +     struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>>> +     unsigned int freq;
>>> +     int ret;
>>> +
>>> +     ret = kstrtouint(buf, 10, &freq);
>>> +     if (ret)
>>> +             return ret;
>>> +
>>> +     if (freq == 0) {
>>> +             stm32_timer_stop(priv);
>>> +     } else {
>>> +             ret = stm32_timer_start(priv, freq);
>>> +             if (ret)
>>> +                     return ret;
>>> +     }
>>> +
>>> +     return len;
>>> +}
>>> +
>>> +static ssize_t stm32_tt_read_frequency(struct device *dev,
>>> +                                    struct device_attribute *attr, char *buf)
>>> +{
>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>> +     struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>>> +     u32 psc, arr, cr1;
>>> +     unsigned long long freq = 0;
>>> +
>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>> +     regmap_read(priv->regmap, TIM_PSC, &psc);
>>> +     regmap_read(priv->regmap, TIM_ARR, &arr);
>>> +
>>> +     if (psc && arr && (cr1 & TIM_CR1_CEN)) {
>>> +             freq = (unsigned long long)clk_get_rate(priv->clk);
>>> +             do_div(freq, psc);
>>> +             do_div(freq, arr);
>>> +     }
>>> +
>>> +     return sprintf(buf, "%d\n", (unsigned int)freq);
>>> +}
>>> +
>>> +static IIO_DEV_ATTR_SAMP_FREQ(0660,
>>> +                           stm32_tt_read_frequency,
>>> +                           stm32_tt_store_frequency);
>>> +
>>> +static struct attribute *stm32_trigger_attrs[] = {
>>> +     &iio_dev_attr_sampling_frequency.dev_attr.attr,
>>> +     NULL,
>>> +};
>>> +
>>> +static const struct attribute_group stm32_trigger_attr_group = {
>>> +     .attrs = stm32_trigger_attrs,
>>> +};
>>> +
>>> +static const struct attribute_group *stm32_trigger_attr_groups[] = {
>>> +     &stm32_trigger_attr_group,
>>> +     NULL,
>>> +};
>>> +
>>> +static char *master_mode_table[] = {
>>> +     "reset",
>>> +     "enable",
>>> +     "update",
>>> +     "compare_pulse",
>>> +     "OC1REF",
>>> +     "OC2REF",
>>> +     "OC3REF",
>>> +     "OC4REF"
>>> +};
>>> +
>>> +static ssize_t stm32_tt_show_master_mode(struct device *dev,
>>> +                                      struct device_attribute *attr,
>>> +                                      char *buf)
>>> +{
>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>> +     u32 cr2;
>>> +
>>> +     regmap_read(priv->regmap, TIM_CR2, &cr2);
>>> +     cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
>>> +
>>> +     return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
>>> +}
>>> +
>>> +static ssize_t stm32_tt_store_master_mode(struct device *dev,
>>> +                                       struct device_attribute *attr,
>>> +                                       const char *buf, size_t len)
>>> +{
>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>> +     int i;
>>> +
>>> +     for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
>>> +             if (!strncmp(master_mode_table[i], buf,
>>> +                          strlen(master_mode_table[i]))) {
>>> +                     regmap_update_bits(priv->regmap, TIM_CR2,
>>> +                                        TIM_CR2_MMS, i << TIM_CR2_MMS_SHIFT);
>>> +                     return len;
>>> +             }
>>> +     }
>>> +
>>> +     return -EINVAL;
>>> +}
>>> +
>>> +static IIO_CONST_ATTR(master_mode_available,
>>> +     "reset enable update compare_pulse OC1REF OC2REF OC3REF OC4REF");
>>> +
>>> +static IIO_DEVICE_ATTR(master_mode, 0660,
>>> +                    stm32_tt_show_master_mode,
>>> +                    stm32_tt_store_master_mode,
>>> +                    0);
>>> +
>>> +static char *slave_mode_table[] = {
>>> +     "disabled",
>>> +     "encoder_1",
>>> +     "encoder_2",
>>> +     "encoder_3",
>>> +     "reset",
>>> +     "gated",
>>> +     "trigger",
>>> +     "external_clock",
>>> +};
>>> +
>>> +static ssize_t stm32_tt_show_slave_mode(struct device *dev,
>>> +                                     struct device_attribute *attr,
>>> +                                     char *buf)
>>> +{
>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>> +     u32 smcr;
>>> +
>>> +     regmap_read(priv->regmap, TIM_SMCR, &smcr);
>>> +     smcr &= TIM_SMCR_SMS;
>>> +
>>> +     return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
>>> +}
>>> +
>>> +static ssize_t stm32_tt_store_slave_mode(struct device *dev,
>>> +                                      struct device_attribute *attr,
>>> +                                      const char *buf, size_t len)
>>> +{
>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>> +     int i;
>>> +
>>> +     for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
>>> +             if (!strncmp(slave_mode_table[i], buf,
>>> +                          strlen(slave_mode_table[i]))) {
>>> +                     regmap_update_bits(priv->regmap,
>>> +                                        TIM_SMCR, TIM_SMCR_SMS, i);
>>> +                     return len;
>>> +             }
>>> +     }
>>> +
>>> +     return -EINVAL;
>>> +}
>>> +
>>> +static IIO_CONST_ATTR(slave_mode_available,
>>> +"disabled encoder_1 encoder_2 encoder_3 reset gated trigger external_clock");
>>> +
>>> +static IIO_DEVICE_ATTR(slave_mode, 0660,
>>> +                    stm32_tt_show_slave_mode,
>>> +                    stm32_tt_store_slave_mode,
>>> +                    0);
>>> +
>>> +static struct attribute *stm32_timer_attrs[] = {
>>> +     &iio_dev_attr_master_mode.dev_attr.attr,
>>> +     &iio_const_attr_master_mode_available.dev_attr.attr,
>>> +     &iio_dev_attr_slave_mode.dev_attr.attr,
>>> +     &iio_const_attr_slave_mode_available.dev_attr.attr,
>>> +     NULL,
>>> +};
>>> +
>>> +static const struct attribute_group stm32_timer_attr_group = {
>>> +     .attrs = stm32_timer_attrs,
>>> +};
>>> +
>>> +static const struct iio_trigger_ops timer_trigger_ops = {
>>> +     .owner = THIS_MODULE,
>>> +};
>>> +
>>> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
>>> +{
>>> +     int ret;
>>> +     const char * const *cur = priv->triggers;
>>> +
>>> +     while (cur && *cur) {
>>> +             struct iio_trigger *trig;
>>> +
>>> +             trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur);
>>> +             if  (!trig)
>>> +                     return -ENOMEM;
>>> +
>>> +             trig->dev.parent = priv->dev->parent;
>>> +             trig->ops = &timer_trigger_ops;
>>> +             trig->dev.groups = stm32_trigger_attr_groups;
>>> +             iio_trigger_set_drvdata(trig, priv);
>>> +
>>> +             ret = devm_iio_trigger_register(priv->dev, trig);
>>> +             if (ret)
>>> +                     return ret;
>>> +             cur++;
>>> +     }
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +/**
>>> + * is_stm32_timer_trigger
>>> + * @trig: trigger to be checked
>>> + *
>>> + * return true if the trigger is a valid stm32 iio timer trigger
>>> + * either return false
>>> + */
>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig)
>>> +{
>>> +     return (trig->ops == &timer_trigger_ops);
>>> +}
>>> +EXPORT_SYMBOL(is_stm32_timer_trigger);
>>> +
>>> +static int stm32_validate_trigger(struct iio_dev *indio_dev,
>>> +                               struct iio_trigger *trig)
>>> +{
>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>> +     const char * const *cur = priv->valids;
>>> +     unsigned int i = 0;
>>> +
>>> +     if (!is_stm32_timer_trigger(trig))
>>> +             return -EINVAL;
>>> +
>>> +     while (cur && *cur) {
>>> +             if (!strncmp(trig->name, *cur, strlen(trig->name))) {
>>> +                     regmap_update_bits(priv->regmap,
>>> +                                        TIM_SMCR, TIM_SMCR_TS,
>>> +                                        i << TIM_SMCR_TS_SHIFT);
>>> +                     return 0;
>>> +             }
>>> +             cur++;
>>> +             i++;
>>> +     }
>>> +
>>> +     return -EINVAL;
>>> +}
>>> +
>>> +static const struct iio_info stm32_trigger_info = {
>>> +     .driver_module = THIS_MODULE,
>>> +     .validate_trigger = stm32_validate_trigger,
>>> +     .attrs = &stm32_timer_attr_group,
>>> +};
>>> +
>>> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
>>> +{
>>> +     struct iio_dev *indio_dev;
>>> +     int ret;
>>> +
>>> +     indio_dev = devm_iio_device_alloc(dev,
>>> +                                       sizeof(struct stm32_timer_trigger));
>>> +     if (!indio_dev)
>>> +             return NULL;
>>> +
>>> +     indio_dev->name = dev_name(dev);
>>> +     indio_dev->dev.parent = dev;
>>> +     indio_dev->info = &stm32_trigger_info;
>>> +     indio_dev->modes = INDIO_EVENT_TRIGGERED;
>>> +     indio_dev->num_channels = 0;
>>> +     indio_dev->dev.of_node = dev->of_node;
>>> +
>>> +     ret = devm_iio_device_register(dev, indio_dev);
>>> +     if (ret)
>>> +             return NULL;
>>> +
>>> +     return iio_priv(indio_dev);
>>> +}
>>> +
>>> +static int stm32_timer_trigger_probe(struct platform_device *pdev)
>>> +{
>>> +     struct device *dev = &pdev->dev;
>>> +     struct stm32_timer_trigger *priv;
>>> +     struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
>>> +     unsigned int index;
>>> +     int ret;
>>> +
>>> +     if (of_property_read_u32(dev->of_node, "reg", &index))
>>> +             return -EINVAL;
>>> +
>>> +     if (index >= ARRAY_SIZE(triggers_table))
>>> +             return -EINVAL;
>>> +
>>> +     /* Create an IIO device only if we have triggers to be validated */
>>> +     if (*valids_table[index])
>>> +             priv = stm32_setup_iio_device(dev);
>>
>> I still don't like this. Really feels like we shouldn't be creating an
>> iio device with all the bagage that carries just to allow us to do the
>> trigger trees.  We ought to have a much more light weight solution for this
>> functionality - we aren't typically even using the interrupt tree stuff
>> that the triggers for devices are all really about.
>>
>> A simpler approach of allowing each trigger the option of a parent seems like
>> it would be cleaner.  Could be done entirely within this driver in the first
>> instance.  Basically it would just look like your master and slave attributes
>> but have those under triggerX not iio:deviceX.
>>
>> We can work out how to make it more generic later - including perhaps the
>> option to trigger from triggers outside this driver, using some parallel
>> infrastructure to the device triggering.
>>
>>
>>> +     else
>>> +             priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>> +
>>> +     if (!priv)
>>> +             return -ENOMEM;
>>> +
>>> +     priv->dev = dev;
>>> +     priv->regmap = ddata->regmap;
>>> +     priv->clk = ddata->clk;
>>> +     priv->max_arr = ddata->max_arr;
>>> +     priv->triggers = triggers_table[index];
>>> +     priv->valids = valids_table[index];
>>> +
>>> +     ret = stm32_setup_iio_triggers(priv);
>>> +     if (ret)
>>> +             return ret;
>>> +
>>> +     platform_set_drvdata(pdev, priv);
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +static const struct of_device_id stm32_trig_of_match[] = {
>>> +     { .compatible = "st,stm32-timer-trigger", },
>>> +     { /* end node */ },
>>> +};
>>> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
>>> +
>>> +static struct platform_driver stm32_timer_trigger_driver = {
>>> +     .probe = stm32_timer_trigger_probe,
>>> +     .driver = {
>>> +             .name = "stm32-timer-trigger",
>>> +             .of_match_table = stm32_trig_of_match,
>>> +     },
>>> +};
>>> +module_platform_driver(stm32_timer_trigger_driver);
>>> +
>>> +MODULE_ALIAS("platform: stm32-timer-trigger");
>>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger driver");
>>> +MODULE_LICENSE("GPL v2");
>>> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
>>> index 809b2e7..f2af4fe 100644
>>> --- a/drivers/iio/trigger/Kconfig
>>> +++ b/drivers/iio/trigger/Kconfig
>>> @@ -46,5 +46,4 @@ config IIO_SYSFS_TRIGGER
>>>
>>>         To compile this driver as a module, choose M here: the
>>>         module will be called iio-trig-sysfs.
>>> -
>> Clean this up.
> 
> ok
> 
>>>  endmenu
>>> diff --git a/include/linux/iio/timer/stm32-timer-trigger.h b/include/linux/iio/timer/stm32-timer-trigger.h
>>> new file mode 100644
>>> index 0000000..55535ae
>>> --- /dev/null
>>> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
>>> @@ -0,0 +1,62 @@
>>> +/*
>>> + * Copyright (C) STMicroelectronics 2016
>>> + *
>>> + * Author: Benjamin Gaignard <[e-mail]>
>>> + *
>>> + * License terms:  GNU General Public License (GPL), version 2
>>> + */
>>> +
>>> +#ifndef _STM32_TIMER_TRIGGER_H_
>>> +#define _STM32_TIMER_TRIGGER_H_
>>> +
>>> +#define TIM1_TRGO    "tim1_trgo"
>>> +#define TIM1_CH1     "tim1_ch1"
>>> +#define TIM1_CH2     "tim1_ch2"
>>> +#define TIM1_CH3     "tim1_ch3"
>>> +#define TIM1_CH4     "tim1_ch4"
>>> +
>>> +#define TIM2_TRGO    "tim2_trgo"
>>> +#define TIM2_CH1     "tim2_ch1"
>>> +#define TIM2_CH2     "tim2_ch2"
>>> +#define TIM2_CH3     "tim2_ch3"
>>> +#define TIM2_CH4     "tim2_ch4"
>>> +
>>> +#define TIM3_TRGO    "tim3_trgo"
>>> +#define TIM3_CH1     "tim3_ch1"
>>> +#define TIM3_CH2     "tim3_ch2"
>>> +#define TIM3_CH3     "tim3_ch3"
>>> +#define TIM3_CH4     "tim3_ch4"
>>> +
>>> +#define TIM4_TRGO    "tim4_trgo"
>>> +#define TIM4_CH1     "tim4_ch1"
>>> +#define TIM4_CH2     "tim4_ch2"
>>> +#define TIM4_CH3     "tim4_ch3"
>>> +#define TIM4_CH4     "tim4_ch4"
>>> +
>>> +#define TIM5_TRGO    "tim5_trgo"
>>> +#define TIM5_CH1     "tim5_ch1"
>>> +#define TIM5_CH2     "tim5_ch2"
>>> +#define TIM5_CH3     "tim5_ch3"
>>> +#define TIM5_CH4     "tim5_ch4"
>>> +
>>> +#define TIM6_TRGO    "tim6_trgo"
>>> +
>>> +#define TIM7_TRGO    "tim7_trgo"
>>> +
>>> +#define TIM8_TRGO    "tim8_trgo"
>>> +#define TIM8_CH1     "tim8_ch1"
>>> +#define TIM8_CH2     "tim8_ch2"
>>> +#define TIM8_CH3     "tim8_ch3"
>>> +#define TIM8_CH4     "tim8_ch4"
>>> +
>>> +#define TIM9_TRGO    "tim9_trgo"
>>> +#define TIM9_CH1     "tim9_ch1"
>>> +#define TIM9_CH2     "tim9_ch2"
>>> +
>>> +#define TIM12_TRGO   "tim12_trgo"
>>> +#define TIM12_CH1    "tim12_ch1"
>>> +#define TIM12_CH2    "tim12_ch2"
>>> +
>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
>>> +
>>> +#endif
>>>
>>
> 
> 
>

Benjamin Gaignard Jan. 3, 2017, 9:23 a.m. UTC | #4

2017-01-02 19:22 GMT+01:00 Jonathan Cameron <[e-mail]>:
> On 02/01/17 08:46, Benjamin Gaignard wrote:
>> 2016-12-30 22:12 GMT+01:00 Jonathan Cameron <[e-mail]>:
>>> On 09/12/16 14:15, Benjamin Gaignard wrote:
>>>> Timers IPs can be used to generate triggers for other IPs like
>>>> DAC, ADC or other timers.
>>>> Each trigger may result of timer internals signals like counter enable,
>>>> reset or edge, this configuration could be done through "master_mode"
>>>> device attribute.
>>>>
>>>> A timer device could be triggered by other timers, we use the trigger
>>>> name and is_stm32_iio_timer_trigger() function to distinguish them
>>>> and configure IP input switch.
>>>>
>>>> Timer may also decide on which event (edge, level) they could
>>>> be activated by a trigger, this configuration is done by writing in
>>>> "slave_mode" device attribute.
>>>>
>>>> Since triggers could also be used by DAC or ADC their names are defined
>>>> in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will be able
>>>> to configure themselves in valid_trigger function
>>>>
>>>> Trigger have a "sampling_frequency" attribute which allow to configure
>>>> timer sampling frequency without using PWM interface
>>>>
>>>> version 5:
>>>> - simplify tables of triggers
>>>> - only create an IIO device when needed
>>>>
>>>> version 4:
>>>> - get triggers configuration from "reg" in DT
>>>> - add tables of triggers
>>>> - sampling frequency is enable/disable when writing in trigger
>>>>   sampling_frequency attribute
>>>> - no more use of interruptions
>>>>
>>>> version 3:
>>>> - change compatible to "st,stm32-timer-trigger"
>>>> - fix attributes access right
>>>> - use string instead of int for master_mode and slave_mode
>>>> - document device attributes in sysfs-bus-iio-timer-stm32
>>>>
>>>> version 2:
>>>> - keep only one compatible
>>>> - use st,input-triggers-names and st,output-triggers-names
>>>>   to know which triggers are accepted and/or create by the device
>>> Firstly, sorry it has taken me so long to get back to this.
>>>
>>> I'm still not keen on this use of iio_device elements just to act as
>>> glue between triggers.  I think we need to work out a more light weight
>>> way to do this.  As you are only using them for validation and to provide
>>> somewhere to hang the control attibutes off, there is nothing stopping us
>>> moving that over to the iio_trigger instead which would avoid the messy
>>> duality going on here.
>>
>> I have add an iio_device because each hardware can generate multiple
>> triggers (up to 5: trgo, ch 1...4) and slave_mode attribute will impact all the
>> triggers of a device. For me it was making sense to centralize that in an
>> iio_device rather than having an attribute "shared" (from hardware
>> point of view)
>> on multiple triggers.
>> Since master_mode attribute is only used by trgo and not impact ch1...4
>> triggers I will move it to trigger instead of the iio_device.
>>
>> I also wanted to be able to connect triggers on a iio_device as I
>> could do for an
>> ADC with a command like 'echo "tim1_trgo" > iio_deviceX/trigger/current_trigger'
> This is interesting, but with a bit of refactoring I would think it would
> be possible to share some of that code thus allowing non IIO devices to
> bind to triggers.  Ultimately I want to be able to bind a trigger to
> a trigger - I appreciate here the topology is more limited than that
> so some complexity comes in.
>
> My gut feeling is that representing that topology explicitly is hard
> to do in a remotely general way, but lets try it and see.
> We run into this sort of interdependency issue between different bits of
> the hardware all the time.  Setting a value somewhere effects the configuration
> elsewhere - often the best plan is to just let that happen and leave it up to
> userspace to check for changes if it cares.

okay

>> If I change that to parent_trigger attribute it change this behavior
>> and I will have to
>> duplicated what is done in iio_trigger_write_current() to find and
>> validate triggers.
> I get the reasoning, but we still end up with something represented
> by an IIO device that isn't providing any channels at all. It's simply
> using some of the infrastructure.  To my mind it is 'something else'
> and should be represented as such.  I have no problem at all with
> you registering additional elements in /sysfs/bus/iio/ to represent
> these shared elements - we already have drivers that do that to
> provide some centralized infrastructure (e.g. the sysfs-trigger)

My hardware block are timers maybe I can add a channel type "IIO_TIMER"
and declare a channel with info_mask_separate = BIT(IIO_CHAN_INFO_SAMP_FREQ)
so I will be able to write/read sampling frequency on IIO device.

> I'm worried about the scope spread we get for an IIO device otherwise.
> They serve a well defined purpose at the moment, and that isn't what
> is happening here.
>
> So my gut feeling is we are better deliberately not representing the
> inter dependence and claiming all triggers we are creating are
> independent.  That way we can have a nice generic infrastructure
> that will work in all cases (be it pushing the sanity checking to
> userspace).
>
> So each trigger has direct access to what controls it.  Changing anything
> can effect other triggers in weird ways.
>
> I'm finding it hard to see anything else generalizing sufficiently
> as we'll always get cases where we can't represent the topology without
> diving into the complexity of something like the media controller
> framework.
>
> Jonathan
>>
>>> I might still be missing something though!
>>>
>>> You would only I think need 3 attributes
>>>
>>> parrent_trigger
>>> and something like your master_mode and slave_mode attributes.
>>>
>>> The parrent_trigger would need some validation etc, but if we keep it
>>> within this driver initially that won't be hard to do. Checking the device
>>> parent matches will do most of it.
>>>
>>> Jonathan
>>>>
>>>> Signed-off-by: Benjamin Gaignard <[e-mail]>
>>>> ---
>>>>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
>>>>  drivers/iio/Kconfig                                |   2 +-
>>>>  drivers/iio/Makefile                               |   1 +
>>>>  drivers/iio/timer/Kconfig                          |  13 +
>>>>  drivers/iio/timer/Makefile                         |   1 +
>>>>  drivers/iio/timer/stm32-timer-trigger.c            | 466 +++++++++++++++++++++
>>>>  drivers/iio/trigger/Kconfig                        |   1 -
>>>>  include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
>>>>  8 files changed, 599 insertions(+), 2 deletions(-)
>>>>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>  create mode 100644 drivers/iio/timer/Kconfig
>>>>  create mode 100644 drivers/iio/timer/Makefile
>>>>  create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
>>>>  create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h
>>>>
>>>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>> new file mode 100644
>>>> index 0000000..26583dd
>>>> --- /dev/null
>>>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>> @@ -0,0 +1,55 @@
>>>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode_available
>>>> +KernelVersion:       4.10
>>>> +Contact:     [e-mail]
>>>> +Description:
>>>> +             Reading returns the list possible master modes which are:
>>>> +             - "reset"     : The UG bit from the TIMx_EGR register is used as trigger output (TRGO).
>>>> +             - "enable"    : The Counter Enable signal CNT_EN is used as trigger output.
>>>> +             - "update"    : The update event is selected as trigger output.
>>>> +                             For instance a master timer can then be used as a prescaler for a slave timer.
>>>> +             - "compare_pulse" : The trigger output send a positive pulse when the CC1IF flag is to be set.
>>>> +             - "OC1REF"    : OC1REF signal is used as trigger output.
>>>> +             - "OC2REF"    : OC2REF signal is used as trigger output.
>>>> +             - "OC3REF"    : OC3REF signal is used as trigger output.
>>>> +             - "OC4REF"    : OC4REF signal is used as trigger output.
>>>> +
>>>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode
>>>> +KernelVersion:       4.10
>>>> +Contact:     [e-mail]
>>>> +Description:
>>>> +             Reading returns the current master modes.
>>>> +             Writing set the master mode
>>>> +
>>>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode_available
>>>> +KernelVersion:       4.10
>>>> +Contact:     [e-mail]
>>>> +Description:
>>>> +             Reading returns the list possible slave modes which are:
>>>> +             - "disabled"  : The prescaler is clocked directly by the internal clock.
>>>> +             - "encoder_1" : Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
>>>> +             - "encoder_2" : Counter counts up/down on TI1FP2 edge depending on TI2FP1 level.
>>>> +             - "encoder_3" : Counter counts up/down on both TI1FP1 and TI2FP2 edges depending
>>>> +                             on the level of the other input.
>>>> +             - "reset"     : Rising edge of the selected trigger input reinitializes the counter
>>>> +                             and generates an update of the registers.
>>>> +             - "gated"     : The counter clock is enabled when the trigger input is high.
>>>> +                             The counter stops (but is not reset) as soon as the trigger becomes low.
>>>> +                             Both start and stop of the counter are controlled.
>>>> +             - "trigger"   : The counter starts at a rising edge of the trigger TRGI (but it is not
>>>> +                             reset). Only the start of the counter is controlled.
>>>> +             - "external_clock": Rising edges of the selected trigger (TRGI) clock the counter.
>>>> +
>>>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode
>>>> +KernelVersion:       4.10
>>>> +Contact:     [e-mail]
>>>> +Description:
>>>> +             Reading returns the current slave mode.
>>>> +             Writing set the slave mode
>>>> +
>>>> +What:                /sys/bus/iio/devices/triggerX/sampling_frequency
>>>> +KernelVersion:       4.10
>>>> +Contact:     [e-mail]
>>>> +Description:
>>>> +             Reading returns the current sampling frequency.
>>>> +             Writing an value different of 0 set and start sampling.
>>>> +             Writing 0 stop sampling.
>>>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>>>> index 6743b18..2de2a80 100644
>>>> --- a/drivers/iio/Kconfig
>>>> +++ b/drivers/iio/Kconfig
>>>> @@ -90,5 +90,5 @@ source "drivers/iio/potentiometer/Kconfig"
>>>>  source "drivers/iio/pressure/Kconfig"
>>>>  source "drivers/iio/proximity/Kconfig"
>>>>  source "drivers/iio/temperature/Kconfig"
>>>> -
>>>> +source "drivers/iio/timer/Kconfig"
>>>>  endif # IIO
>>>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>>>> index 87e4c43..b797c08 100644
>>>> --- a/drivers/iio/Makefile
>>>> +++ b/drivers/iio/Makefile
>>>> @@ -32,4 +32,5 @@ obj-y += potentiometer/
>>>>  obj-y += pressure/
>>>>  obj-y += proximity/
>>>>  obj-y += temperature/
>>>> +obj-y += timer/
>>>>  obj-y += trigger/
>>>> diff --git a/drivers/iio/timer/Kconfig b/drivers/iio/timer/Kconfig
>>>> new file mode 100644
>>>> index 0000000..e3c21f2
>>>> --- /dev/null
>>>> +++ b/drivers/iio/timer/Kconfig
>>>> @@ -0,0 +1,13 @@
>>>> +#
>>>> +# Timers drivers
>>>> +
>>>> +menu "Timers"
>>>> +
>>>> +config IIO_STM32_TIMER_TRIGGER
>>>> +     tristate "STM32 Timer Trigger"
>>>> +     depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) || COMPILE_TEST
>>>> +     select IIO_TRIGGERED_EVENT
>>>> +     help
>>>> +       Select this option to enable STM32 Timer Trigger
>>>> +
>>>> +endmenu
>>>> diff --git a/drivers/iio/timer/Makefile b/drivers/iio/timer/Makefile
>>>> new file mode 100644
>>>> index 0000000..4ad95ec9
>>>> --- /dev/null
>>>> +++ b/drivers/iio/timer/Makefile
>>>> @@ -0,0 +1 @@
>>>> +obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
>>>> diff --git a/drivers/iio/timer/stm32-timer-trigger.c b/drivers/iio/timer/stm32-timer-trigger.c
>>>> new file mode 100644
>>>> index 0000000..8d16e8f
>>>> --- /dev/null
>>>> +++ b/drivers/iio/timer/stm32-timer-trigger.c
>>>> @@ -0,0 +1,466 @@
>>>> +/*
>>>> + * Copyright (C) STMicroelectronics 2016
>>>> + *
>>>> + * Author: Benjamin Gaignard <[e-mail]>
>>>> + *
>>>> + * License terms:  GNU General Public License (GPL), version 2
>>>> + */
>>>> +
>>>> +#include <linux/iio/iio.h>
>>>> +#include <linux/iio/sysfs.h>
>>>> +#include <linux/iio/timer/stm32-timer-trigger.h>
>>>> +#include <linux/iio/trigger.h>
>>>> +#include <linux/iio/triggered_event.h>
>>>> +#include <linux/interrupt.h>
>>>> +#include <linux/mfd/stm32-timers.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/platform_device.h>
>>>> +
>>>> +#define MAX_TRIGGERS 6
>>>> +#define MAX_VALIDS 5
>>>> +
>>>> +/* List the triggers created by each timer */
>>>> +static const void *triggers_table[][MAX_TRIGGERS] = {
>>>> +     { TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
>>>> +     { TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
>>>> +     { TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
>>>> +     { TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
>>>> +     { TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
>>>> +     { TIM6_TRGO,},
>>>> +     { TIM7_TRGO,},
>>>> +     { TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
>>>> +     { TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
>>>> +     { TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
>>>> +};
>>>> +
>>>> +/* List the triggers accepted by each timer */
>>>> +static const void *valids_table[][MAX_VALIDS] = {
>>>> +     { TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
>>>> +     { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
>>>> +     { TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
>>>> +     { TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
>>>> +     { TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
>>>> +     { }, /* timer 6 */
>>>> +     { }, /* timer 7 */
>>>> +     { TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
>>>> +     { TIM2_TRGO, TIM3_TRGO,},
>>>> +     { TIM4_TRGO, TIM5_TRGO,},
>>>> +};
>>>> +
>>>> +struct stm32_timer_trigger {
>>>> +     struct device *dev;
>>>> +     struct regmap *regmap;
>>>> +     struct clk *clk;
>>>> +     u32 max_arr;
>>>> +     const void *triggers;
>>>> +     const void *valids;
>>>> +};
>>>> +
>>>> +static int stm32_timer_start(struct stm32_timer_trigger *priv,
>>>> +                          unsigned int frequency)
>>>> +{
>>>> +     unsigned long long prd, div;
>>>> +     int prescaler = 0;
>>>> +     u32 ccer, cr1;
>>>> +
>>>> +     /* Period and prescaler values depends of clock rate */
>>>> +     div = (unsigned long long)clk_get_rate(priv->clk);
>>>> +
>>>> +     do_div(div, frequency);
>>>> +
>>>> +     prd = div;
>>>> +
>>>> +     /*
>>>> +      * Increase prescaler value until we get a result that fit
>>>> +      * with auto reload register maximum value.
>>>> +      */
>>>> +     while (div > priv->max_arr) {
>>>> +             prescaler++;
>>>> +             div = prd;
>>>> +             do_div(div, (prescaler + 1));
>>>> +     }
>>>> +     prd = div;
>>>> +
>>>> +     if (prescaler > MAX_TIM_PSC) {
>>>> +             dev_err(priv->dev, "prescaler exceeds the maximum value\n");
>>>> +             return -EINVAL;
>>>> +     }
>>>> +
>>>> +     /* Check if nobody else use the timer */
>>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>>> +     if (ccer & TIM_CCER_CCXE)
>>>> +             return -EBUSY;
>>>> +
>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>> +     if (!(cr1 & TIM_CR1_CEN))
>>>> +             clk_enable(priv->clk);
>>>> +
>>>> +     regmap_write(priv->regmap, TIM_PSC, prescaler);
>>>> +     regmap_write(priv->regmap, TIM_ARR, prd - 1);
>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
>>>> +
>>>> +     /* Force master mode to update mode */
>>>> +     regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
>>>> +
>>>> +     /* Make sure that registers are updated */
>>>> +     regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
>>>> +
>>>> +     /* Enable controller */
>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
>>>> +
>>>> +     return 0;
>>>> +}
>>>> +
>>>> +static void stm32_timer_stop(struct stm32_timer_trigger *priv)
>>>> +{
>>>> +     u32 ccer, cr1;
>>>> +
>>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>>> +     if (ccer & TIM_CCER_CCXE)
>>>> +             return;
>>>> +
>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>> +     if (cr1 & TIM_CR1_CEN)
>>>> +             clk_disable(priv->clk);
>>>> +
>>>> +     /* Stop timer */
>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
>>>> +     regmap_write(priv->regmap, TIM_PSC, 0);
>>>> +     regmap_write(priv->regmap, TIM_ARR, 0);
>>>> +}
>>>> +
>>>> +static ssize_t stm32_tt_store_frequency(struct device *dev,
>>>> +                                     struct device_attribute *attr,
>>>> +                                     const char *buf, size_t len)
>>>> +{
>>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>>> +     struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>>>> +     unsigned int freq;
>>>> +     int ret;
>>>> +
>>>> +     ret = kstrtouint(buf, 10, &freq);
>>>> +     if (ret)
>>>> +             return ret;
>>>> +
>>>> +     if (freq == 0) {
>>>> +             stm32_timer_stop(priv);
>>>> +     } else {
>>>> +             ret = stm32_timer_start(priv, freq);
>>>> +             if (ret)
>>>> +                     return ret;
>>>> +     }
>>>> +
>>>> +     return len;
>>>> +}
>>>> +
>>>> +static ssize_t stm32_tt_read_frequency(struct device *dev,
>>>> +                                    struct device_attribute *attr, char *buf)
>>>> +{
>>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>>> +     struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>>>> +     u32 psc, arr, cr1;
>>>> +     unsigned long long freq = 0;
>>>> +
>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>> +     regmap_read(priv->regmap, TIM_PSC, &psc);
>>>> +     regmap_read(priv->regmap, TIM_ARR, &arr);
>>>> +
>>>> +     if (psc && arr && (cr1 & TIM_CR1_CEN)) {
>>>> +             freq = (unsigned long long)clk_get_rate(priv->clk);
>>>> +             do_div(freq, psc);
>>>> +             do_div(freq, arr);
>>>> +     }
>>>> +
>>>> +     return sprintf(buf, "%d\n", (unsigned int)freq);
>>>> +}
>>>> +
>>>> +static IIO_DEV_ATTR_SAMP_FREQ(0660,
>>>> +                           stm32_tt_read_frequency,
>>>> +                           stm32_tt_store_frequency);
>>>> +
>>>> +static struct attribute *stm32_trigger_attrs[] = {
>>>> +     &iio_dev_attr_sampling_frequency.dev_attr.attr,
>>>> +     NULL,
>>>> +};
>>>> +
>>>> +static const struct attribute_group stm32_trigger_attr_group = {
>>>> +     .attrs = stm32_trigger_attrs,
>>>> +};
>>>> +
>>>> +static const struct attribute_group *stm32_trigger_attr_groups[] = {
>>>> +     &stm32_trigger_attr_group,
>>>> +     NULL,
>>>> +};
>>>> +
>>>> +static char *master_mode_table[] = {
>>>> +     "reset",
>>>> +     "enable",
>>>> +     "update",
>>>> +     "compare_pulse",
>>>> +     "OC1REF",
>>>> +     "OC2REF",
>>>> +     "OC3REF",
>>>> +     "OC4REF"
>>>> +};
>>>> +
>>>> +static ssize_t stm32_tt_show_master_mode(struct device *dev,
>>>> +                                      struct device_attribute *attr,
>>>> +                                      char *buf)
>>>> +{
>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>> +     u32 cr2;
>>>> +
>>>> +     regmap_read(priv->regmap, TIM_CR2, &cr2);
>>>> +     cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
>>>> +
>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
>>>> +}
>>>> +
>>>> +static ssize_t stm32_tt_store_master_mode(struct device *dev,
>>>> +                                       struct device_attribute *attr,
>>>> +                                       const char *buf, size_t len)
>>>> +{
>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>> +     int i;
>>>> +
>>>> +     for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
>>>> +             if (!strncmp(master_mode_table[i], buf,
>>>> +                          strlen(master_mode_table[i]))) {
>>>> +                     regmap_update_bits(priv->regmap, TIM_CR2,
>>>> +                                        TIM_CR2_MMS, i << TIM_CR2_MMS_SHIFT);
>>>> +                     return len;
>>>> +             }
>>>> +     }
>>>> +
>>>> +     return -EINVAL;
>>>> +}
>>>> +
>>>> +static IIO_CONST_ATTR(master_mode_available,
>>>> +     "reset enable update compare_pulse OC1REF OC2REF OC3REF OC4REF");
>>>> +
>>>> +static IIO_DEVICE_ATTR(master_mode, 0660,
>>>> +                    stm32_tt_show_master_mode,
>>>> +                    stm32_tt_store_master_mode,
>>>> +                    0);
>>>> +
>>>> +static char *slave_mode_table[] = {
>>>> +     "disabled",
>>>> +     "encoder_1",
>>>> +     "encoder_2",
>>>> +     "encoder_3",
>>>> +     "reset",
>>>> +     "gated",
>>>> +     "trigger",
>>>> +     "external_clock",
>>>> +};
>>>> +
>>>> +static ssize_t stm32_tt_show_slave_mode(struct device *dev,
>>>> +                                     struct device_attribute *attr,
>>>> +                                     char *buf)
>>>> +{
>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>> +     u32 smcr;
>>>> +
>>>> +     regmap_read(priv->regmap, TIM_SMCR, &smcr);
>>>> +     smcr &= TIM_SMCR_SMS;
>>>> +
>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
>>>> +}
>>>> +
>>>> +static ssize_t stm32_tt_store_slave_mode(struct device *dev,
>>>> +                                      struct device_attribute *attr,
>>>> +                                      const char *buf, size_t len)
>>>> +{
>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>> +     int i;
>>>> +
>>>> +     for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
>>>> +             if (!strncmp(slave_mode_table[i], buf,
>>>> +                          strlen(slave_mode_table[i]))) {
>>>> +                     regmap_update_bits(priv->regmap,
>>>> +                                        TIM_SMCR, TIM_SMCR_SMS, i);
>>>> +                     return len;
>>>> +             }
>>>> +     }
>>>> +
>>>> +     return -EINVAL;
>>>> +}
>>>> +
>>>> +static IIO_CONST_ATTR(slave_mode_available,
>>>> +"disabled encoder_1 encoder_2 encoder_3 reset gated trigger external_clock");
>>>> +
>>>> +static IIO_DEVICE_ATTR(slave_mode, 0660,
>>>> +                    stm32_tt_show_slave_mode,
>>>> +                    stm32_tt_store_slave_mode,
>>>> +                    0);
>>>> +
>>>> +static struct attribute *stm32_timer_attrs[] = {
>>>> +     &iio_dev_attr_master_mode.dev_attr.attr,
>>>> +     &iio_const_attr_master_mode_available.dev_attr.attr,
>>>> +     &iio_dev_attr_slave_mode.dev_attr.attr,
>>>> +     &iio_const_attr_slave_mode_available.dev_attr.attr,
>>>> +     NULL,
>>>> +};
>>>> +
>>>> +static const struct attribute_group stm32_timer_attr_group = {
>>>> +     .attrs = stm32_timer_attrs,
>>>> +};
>>>> +
>>>> +static const struct iio_trigger_ops timer_trigger_ops = {
>>>> +     .owner = THIS_MODULE,
>>>> +};
>>>> +
>>>> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
>>>> +{
>>>> +     int ret;
>>>> +     const char * const *cur = priv->triggers;
>>>> +
>>>> +     while (cur && *cur) {
>>>> +             struct iio_trigger *trig;
>>>> +
>>>> +             trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur);
>>>> +             if  (!trig)
>>>> +                     return -ENOMEM;
>>>> +
>>>> +             trig->dev.parent = priv->dev->parent;
>>>> +             trig->ops = &timer_trigger_ops;
>>>> +             trig->dev.groups = stm32_trigger_attr_groups;
>>>> +             iio_trigger_set_drvdata(trig, priv);
>>>> +
>>>> +             ret = devm_iio_trigger_register(priv->dev, trig);
>>>> +             if (ret)
>>>> +                     return ret;
>>>> +             cur++;
>>>> +     }
>>>> +
>>>> +     return 0;
>>>> +}
>>>> +
>>>> +/**
>>>> + * is_stm32_timer_trigger
>>>> + * @trig: trigger to be checked
>>>> + *
>>>> + * return true if the trigger is a valid stm32 iio timer trigger
>>>> + * either return false
>>>> + */
>>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig)
>>>> +{
>>>> +     return (trig->ops == &timer_trigger_ops);
>>>> +}
>>>> +EXPORT_SYMBOL(is_stm32_timer_trigger);
>>>> +
>>>> +static int stm32_validate_trigger(struct iio_dev *indio_dev,
>>>> +                               struct iio_trigger *trig)
>>>> +{
>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>> +     const char * const *cur = priv->valids;
>>>> +     unsigned int i = 0;
>>>> +
>>>> +     if (!is_stm32_timer_trigger(trig))
>>>> +             return -EINVAL;
>>>> +
>>>> +     while (cur && *cur) {
>>>> +             if (!strncmp(trig->name, *cur, strlen(trig->name))) {
>>>> +                     regmap_update_bits(priv->regmap,
>>>> +                                        TIM_SMCR, TIM_SMCR_TS,
>>>> +                                        i << TIM_SMCR_TS_SHIFT);
>>>> +                     return 0;
>>>> +             }
>>>> +             cur++;
>>>> +             i++;
>>>> +     }
>>>> +
>>>> +     return -EINVAL;
>>>> +}
>>>> +
>>>> +static const struct iio_info stm32_trigger_info = {
>>>> +     .driver_module = THIS_MODULE,
>>>> +     .validate_trigger = stm32_validate_trigger,
>>>> +     .attrs = &stm32_timer_attr_group,
>>>> +};
>>>> +
>>>> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
>>>> +{
>>>> +     struct iio_dev *indio_dev;
>>>> +     int ret;
>>>> +
>>>> +     indio_dev = devm_iio_device_alloc(dev,
>>>> +                                       sizeof(struct stm32_timer_trigger));
>>>> +     if (!indio_dev)
>>>> +             return NULL;
>>>> +
>>>> +     indio_dev->name = dev_name(dev);
>>>> +     indio_dev->dev.parent = dev;
>>>> +     indio_dev->info = &stm32_trigger_info;
>>>> +     indio_dev->modes = INDIO_EVENT_TRIGGERED;
>>>> +     indio_dev->num_channels = 0;
>>>> +     indio_dev->dev.of_node = dev->of_node;
>>>> +
>>>> +     ret = devm_iio_device_register(dev, indio_dev);
>>>> +     if (ret)
>>>> +             return NULL;
>>>> +
>>>> +     return iio_priv(indio_dev);
>>>> +}
>>>> +
>>>> +static int stm32_timer_trigger_probe(struct platform_device *pdev)
>>>> +{
>>>> +     struct device *dev = &pdev->dev;
>>>> +     struct stm32_timer_trigger *priv;
>>>> +     struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
>>>> +     unsigned int index;
>>>> +     int ret;
>>>> +
>>>> +     if (of_property_read_u32(dev->of_node, "reg", &index))
>>>> +             return -EINVAL;
>>>> +
>>>> +     if (index >= ARRAY_SIZE(triggers_table))
>>>> +             return -EINVAL;
>>>> +
>>>> +     /* Create an IIO device only if we have triggers to be validated */
>>>> +     if (*valids_table[index])
>>>> +             priv = stm32_setup_iio_device(dev);
>>>
>>> I still don't like this. Really feels like we shouldn't be creating an
>>> iio device with all the bagage that carries just to allow us to do the
>>> trigger trees.  We ought to have a much more light weight solution for this
>>> functionality - we aren't typically even using the interrupt tree stuff
>>> that the triggers for devices are all really about.
>>>
>>> A simpler approach of allowing each trigger the option of a parent seems like
>>> it would be cleaner.  Could be done entirely within this driver in the first
>>> instance.  Basically it would just look like your master and slave attributes
>>> but have those under triggerX not iio:deviceX.
>>>
>>> We can work out how to make it more generic later - including perhaps the
>>> option to trigger from triggers outside this driver, using some parallel
>>> infrastructure to the device triggering.
>>>
>>>
>>>> +     else
>>>> +             priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>>> +
>>>> +     if (!priv)
>>>> +             return -ENOMEM;
>>>> +
>>>> +     priv->dev = dev;
>>>> +     priv->regmap = ddata->regmap;
>>>> +     priv->clk = ddata->clk;
>>>> +     priv->max_arr = ddata->max_arr;
>>>> +     priv->triggers = triggers_table[index];
>>>> +     priv->valids = valids_table[index];
>>>> +
>>>> +     ret = stm32_setup_iio_triggers(priv);
>>>> +     if (ret)
>>>> +             return ret;
>>>> +
>>>> +     platform_set_drvdata(pdev, priv);
>>>> +
>>>> +     return 0;
>>>> +}
>>>> +
>>>> +static const struct of_device_id stm32_trig_of_match[] = {
>>>> +     { .compatible = "st,stm32-timer-trigger", },
>>>> +     { /* end node */ },
>>>> +};
>>>> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
>>>> +
>>>> +static struct platform_driver stm32_timer_trigger_driver = {
>>>> +     .probe = stm32_timer_trigger_probe,
>>>> +     .driver = {
>>>> +             .name = "stm32-timer-trigger",
>>>> +             .of_match_table = stm32_trig_of_match,
>>>> +     },
>>>> +};
>>>> +module_platform_driver(stm32_timer_trigger_driver);
>>>> +
>>>> +MODULE_ALIAS("platform: stm32-timer-trigger");
>>>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger driver");
>>>> +MODULE_LICENSE("GPL v2");
>>>> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
>>>> index 809b2e7..f2af4fe 100644
>>>> --- a/drivers/iio/trigger/Kconfig
>>>> +++ b/drivers/iio/trigger/Kconfig
>>>> @@ -46,5 +46,4 @@ config IIO_SYSFS_TRIGGER
>>>>
>>>>         To compile this driver as a module, choose M here: the
>>>>         module will be called iio-trig-sysfs.
>>>> -
>>> Clean this up.
>>
>> ok
>>
>>>>  endmenu
>>>> diff --git a/include/linux/iio/timer/stm32-timer-trigger.h b/include/linux/iio/timer/stm32-timer-trigger.h
>>>> new file mode 100644
>>>> index 0000000..55535ae
>>>> --- /dev/null
>>>> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
>>>> @@ -0,0 +1,62 @@
>>>> +/*
>>>> + * Copyright (C) STMicroelectronics 2016
>>>> + *
>>>> + * Author: Benjamin Gaignard <[e-mail]>
>>>> + *
>>>> + * License terms:  GNU General Public License (GPL), version 2
>>>> + */
>>>> +
>>>> +#ifndef _STM32_TIMER_TRIGGER_H_
>>>> +#define _STM32_TIMER_TRIGGER_H_
>>>> +
>>>> +#define TIM1_TRGO    "tim1_trgo"
>>>> +#define TIM1_CH1     "tim1_ch1"
>>>> +#define TIM1_CH2     "tim1_ch2"
>>>> +#define TIM1_CH3     "tim1_ch3"
>>>> +#define TIM1_CH4     "tim1_ch4"
>>>> +
>>>> +#define TIM2_TRGO    "tim2_trgo"
>>>> +#define TIM2_CH1     "tim2_ch1"
>>>> +#define TIM2_CH2     "tim2_ch2"
>>>> +#define TIM2_CH3     "tim2_ch3"
>>>> +#define TIM2_CH4     "tim2_ch4"
>>>> +
>>>> +#define TIM3_TRGO    "tim3_trgo"
>>>> +#define TIM3_CH1     "tim3_ch1"
>>>> +#define TIM3_CH2     "tim3_ch2"
>>>> +#define TIM3_CH3     "tim3_ch3"
>>>> +#define TIM3_CH4     "tim3_ch4"
>>>> +
>>>> +#define TIM4_TRGO    "tim4_trgo"
>>>> +#define TIM4_CH1     "tim4_ch1"
>>>> +#define TIM4_CH2     "tim4_ch2"
>>>> +#define TIM4_CH3     "tim4_ch3"
>>>> +#define TIM4_CH4     "tim4_ch4"
>>>> +
>>>> +#define TIM5_TRGO    "tim5_trgo"
>>>> +#define TIM5_CH1     "tim5_ch1"
>>>> +#define TIM5_CH2     "tim5_ch2"
>>>> +#define TIM5_CH3     "tim5_ch3"
>>>> +#define TIM5_CH4     "tim5_ch4"
>>>> +
>>>> +#define TIM6_TRGO    "tim6_trgo"
>>>> +
>>>> +#define TIM7_TRGO    "tim7_trgo"
>>>> +
>>>> +#define TIM8_TRGO    "tim8_trgo"
>>>> +#define TIM8_CH1     "tim8_ch1"
>>>> +#define TIM8_CH2     "tim8_ch2"
>>>> +#define TIM8_CH3     "tim8_ch3"
>>>> +#define TIM8_CH4     "tim8_ch4"
>>>> +
>>>> +#define TIM9_TRGO    "tim9_trgo"
>>>> +#define TIM9_CH1     "tim9_ch1"
>>>> +#define TIM9_CH2     "tim9_ch2"
>>>> +
>>>> +#define TIM12_TRGO   "tim12_trgo"
>>>> +#define TIM12_CH1    "tim12_ch1"
>>>> +#define TIM12_CH2    "tim12_ch2"
>>>> +
>>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
>>>> +
>>>> +#endif
>>>>
>>>
>>
>>
>>
>

Benjamin Gaignard Jan. 3, 2017, 12:59 p.m. UTC | #5

2017-01-03 10:23 GMT+01:00 Benjamin Gaignard <[e-mail]>:
> 2017-01-02 19:22 GMT+01:00 Jonathan Cameron <[e-mail]>:
>> On 02/01/17 08:46, Benjamin Gaignard wrote:
>>> 2016-12-30 22:12 GMT+01:00 Jonathan Cameron <[e-mail]>:
>>>> On 09/12/16 14:15, Benjamin Gaignard wrote:
>>>>> Timers IPs can be used to generate triggers for other IPs like
>>>>> DAC, ADC or other timers.
>>>>> Each trigger may result of timer internals signals like counter enable,
>>>>> reset or edge, this configuration could be done through "master_mode"
>>>>> device attribute.
>>>>>
>>>>> A timer device could be triggered by other timers, we use the trigger
>>>>> name and is_stm32_iio_timer_trigger() function to distinguish them
>>>>> and configure IP input switch.
>>>>>
>>>>> Timer may also decide on which event (edge, level) they could
>>>>> be activated by a trigger, this configuration is done by writing in
>>>>> "slave_mode" device attribute.
>>>>>
>>>>> Since triggers could also be used by DAC or ADC their names are defined
>>>>> in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will be able
>>>>> to configure themselves in valid_trigger function
>>>>>
>>>>> Trigger have a "sampling_frequency" attribute which allow to configure
>>>>> timer sampling frequency without using PWM interface
>>>>>
>>>>> version 5:
>>>>> - simplify tables of triggers
>>>>> - only create an IIO device when needed
>>>>>
>>>>> version 4:
>>>>> - get triggers configuration from "reg" in DT
>>>>> - add tables of triggers
>>>>> - sampling frequency is enable/disable when writing in trigger
>>>>>   sampling_frequency attribute
>>>>> - no more use of interruptions
>>>>>
>>>>> version 3:
>>>>> - change compatible to "st,stm32-timer-trigger"
>>>>> - fix attributes access right
>>>>> - use string instead of int for master_mode and slave_mode
>>>>> - document device attributes in sysfs-bus-iio-timer-stm32
>>>>>
>>>>> version 2:
>>>>> - keep only one compatible
>>>>> - use st,input-triggers-names and st,output-triggers-names
>>>>>   to know which triggers are accepted and/or create by the device
>>>> Firstly, sorry it has taken me so long to get back to this.
>>>>
>>>> I'm still not keen on this use of iio_device elements just to act as
>>>> glue between triggers.  I think we need to work out a more light weight
>>>> way to do this.  As you are only using them for validation and to provide
>>>> somewhere to hang the control attibutes off, there is nothing stopping us
>>>> moving that over to the iio_trigger instead which would avoid the messy
>>>> duality going on here.
>>>
>>> I have add an iio_device because each hardware can generate multiple
>>> triggers (up to 5: trgo, ch 1...4) and slave_mode attribute will impact all the
>>> triggers of a device. For me it was making sense to centralize that in an
>>> iio_device rather than having an attribute "shared" (from hardware
>>> point of view)
>>> on multiple triggers.
>>> Since master_mode attribute is only used by trgo and not impact ch1...4
>>> triggers I will move it to trigger instead of the iio_device.
>>>
>>> I also wanted to be able to connect triggers on a iio_device as I
>>> could do for an
>>> ADC with a command like 'echo "tim1_trgo" > iio_deviceX/trigger/current_trigger'
>> This is interesting, but with a bit of refactoring I would think it would
>> be possible to share some of that code thus allowing non IIO devices to
>> bind to triggers.  Ultimately I want to be able to bind a trigger to
>> a trigger - I appreciate here the topology is more limited than that
>> so some complexity comes in.
>>
>> My gut feeling is that representing that topology explicitly is hard
>> to do in a remotely general way, but lets try it and see.
>> We run into this sort of interdependency issue between different bits of
>> the hardware all the time.  Setting a value somewhere effects the configuration
>> elsewhere - often the best plan is to just let that happen and leave it up to
>> userspace to check for changes if it cares.
>
> okay
>
>>> If I change that to parent_trigger attribute it change this behavior
>>> and I will have to
>>> duplicated what is done in iio_trigger_write_current() to find and
>>> validate triggers.
>> I get the reasoning, but we still end up with something represented
>> by an IIO device that isn't providing any channels at all. It's simply
>> using some of the infrastructure.  To my mind it is 'something else'
>> and should be represented as such.  I have no problem at all with
>> you registering additional elements in /sysfs/bus/iio/ to represent
>> these shared elements - we already have drivers that do that to
>> provide some centralized infrastructure (e.g. the sysfs-trigger)
>
> My hardware block are timers maybe I can add a channel type "IIO_TIMER"
> and declare a channel with info_mask_separate = BIT(IIO_CHAN_INFO_SAMP_FREQ)
> so I will be able to write/read sampling frequency on IIO device.
>

If it isn't possible to implement IIO_TIMER I will simply drop device part of
my driver until we find a solution because I would like to upstream at
least what is
need to ADC/DAC.

>> I'm worried about the scope spread we get for an IIO device otherwise.
>> They serve a well defined purpose at the moment, and that isn't what
>> is happening here.
>>
>> So my gut feeling is we are better deliberately not representing the
>> inter dependence and claiming all triggers we are creating are
>> independent.  That way we can have a nice generic infrastructure
>> that will work in all cases (be it pushing the sanity checking to
>> userspace).
>>
>> So each trigger has direct access to what controls it.  Changing anything
>> can effect other triggers in weird ways.
>>
>> I'm finding it hard to see anything else generalizing sufficiently
>> as we'll always get cases where we can't represent the topology without
>> diving into the complexity of something like the media controller
>> framework.
>>
>> Jonathan
>>>
>>>> I might still be missing something though!
>>>>
>>>> You would only I think need 3 attributes
>>>>
>>>> parrent_trigger
>>>> and something like your master_mode and slave_mode attributes.
>>>>
>>>> The parrent_trigger would need some validation etc, but if we keep it
>>>> within this driver initially that won't be hard to do. Checking the device
>>>> parent matches will do most of it.
>>>>
>>>> Jonathan
>>>>>
>>>>> Signed-off-by: Benjamin Gaignard <[e-mail]>
>>>>> ---
>>>>>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
>>>>>  drivers/iio/Kconfig                                |   2 +-
>>>>>  drivers/iio/Makefile                               |   1 +
>>>>>  drivers/iio/timer/Kconfig                          |  13 +
>>>>>  drivers/iio/timer/Makefile                         |   1 +
>>>>>  drivers/iio/timer/stm32-timer-trigger.c            | 466 +++++++++++++++++++++
>>>>>  drivers/iio/trigger/Kconfig                        |   1 -
>>>>>  include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
>>>>>  8 files changed, 599 insertions(+), 2 deletions(-)
>>>>>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>>  create mode 100644 drivers/iio/timer/Kconfig
>>>>>  create mode 100644 drivers/iio/timer/Makefile
>>>>>  create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
>>>>>  create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h
>>>>>
>>>>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>> new file mode 100644
>>>>> index 0000000..26583dd
>>>>> --- /dev/null
>>>>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>> @@ -0,0 +1,55 @@
>>>>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode_available
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the list possible master modes which are:
>>>>> +             - "reset"     : The UG bit from the TIMx_EGR register is used as trigger output (TRGO).
>>>>> +             - "enable"    : The Counter Enable signal CNT_EN is used as trigger output.
>>>>> +             - "update"    : The update event is selected as trigger output.
>>>>> +                             For instance a master timer can then be used as a prescaler for a slave timer.
>>>>> +             - "compare_pulse" : The trigger output send a positive pulse when the CC1IF flag is to be set.
>>>>> +             - "OC1REF"    : OC1REF signal is used as trigger output.
>>>>> +             - "OC2REF"    : OC2REF signal is used as trigger output.
>>>>> +             - "OC3REF"    : OC3REF signal is used as trigger output.
>>>>> +             - "OC4REF"    : OC4REF signal is used as trigger output.
>>>>> +
>>>>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the current master modes.
>>>>> +             Writing set the master mode
>>>>> +
>>>>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode_available
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the list possible slave modes which are:
>>>>> +             - "disabled"  : The prescaler is clocked directly by the internal clock.
>>>>> +             - "encoder_1" : Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
>>>>> +             - "encoder_2" : Counter counts up/down on TI1FP2 edge depending on TI2FP1 level.
>>>>> +             - "encoder_3" : Counter counts up/down on both TI1FP1 and TI2FP2 edges depending
>>>>> +                             on the level of the other input.
>>>>> +             - "reset"     : Rising edge of the selected trigger input reinitializes the counter
>>>>> +                             and generates an update of the registers.
>>>>> +             - "gated"     : The counter clock is enabled when the trigger input is high.
>>>>> +                             The counter stops (but is not reset) as soon as the trigger becomes low.
>>>>> +                             Both start and stop of the counter are controlled.
>>>>> +             - "trigger"   : The counter starts at a rising edge of the trigger TRGI (but it is not
>>>>> +                             reset). Only the start of the counter is controlled.
>>>>> +             - "external_clock": Rising edges of the selected trigger (TRGI) clock the counter.
>>>>> +
>>>>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the current slave mode.
>>>>> +             Writing set the slave mode
>>>>> +
>>>>> +What:                /sys/bus/iio/devices/triggerX/sampling_frequency
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the current sampling frequency.
>>>>> +             Writing an value different of 0 set and start sampling.
>>>>> +             Writing 0 stop sampling.
>>>>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>>>>> index 6743b18..2de2a80 100644
>>>>> --- a/drivers/iio/Kconfig
>>>>> +++ b/drivers/iio/Kconfig
>>>>> @@ -90,5 +90,5 @@ source "drivers/iio/potentiometer/Kconfig"
>>>>>  source "drivers/iio/pressure/Kconfig"
>>>>>  source "drivers/iio/proximity/Kconfig"
>>>>>  source "drivers/iio/temperature/Kconfig"
>>>>> -
>>>>> +source "drivers/iio/timer/Kconfig"
>>>>>  endif # IIO
>>>>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>>>>> index 87e4c43..b797c08 100644
>>>>> --- a/drivers/iio/Makefile
>>>>> +++ b/drivers/iio/Makefile
>>>>> @@ -32,4 +32,5 @@ obj-y += potentiometer/
>>>>>  obj-y += pressure/
>>>>>  obj-y += proximity/
>>>>>  obj-y += temperature/
>>>>> +obj-y += timer/
>>>>>  obj-y += trigger/
>>>>> diff --git a/drivers/iio/timer/Kconfig b/drivers/iio/timer/Kconfig
>>>>> new file mode 100644
>>>>> index 0000000..e3c21f2
>>>>> --- /dev/null
>>>>> +++ b/drivers/iio/timer/Kconfig
>>>>> @@ -0,0 +1,13 @@
>>>>> +#
>>>>> +# Timers drivers
>>>>> +
>>>>> +menu "Timers"
>>>>> +
>>>>> +config IIO_STM32_TIMER_TRIGGER
>>>>> +     tristate "STM32 Timer Trigger"
>>>>> +     depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) || COMPILE_TEST
>>>>> +     select IIO_TRIGGERED_EVENT
>>>>> +     help
>>>>> +       Select this option to enable STM32 Timer Trigger
>>>>> +
>>>>> +endmenu
>>>>> diff --git a/drivers/iio/timer/Makefile b/drivers/iio/timer/Makefile
>>>>> new file mode 100644
>>>>> index 0000000..4ad95ec9
>>>>> --- /dev/null
>>>>> +++ b/drivers/iio/timer/Makefile
>>>>> @@ -0,0 +1 @@
>>>>> +obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
>>>>> diff --git a/drivers/iio/timer/stm32-timer-trigger.c b/drivers/iio/timer/stm32-timer-trigger.c
>>>>> new file mode 100644
>>>>> index 0000000..8d16e8f
>>>>> --- /dev/null
>>>>> +++ b/drivers/iio/timer/stm32-timer-trigger.c
>>>>> @@ -0,0 +1,466 @@
>>>>> +/*
>>>>> + * Copyright (C) STMicroelectronics 2016
>>>>> + *
>>>>> + * Author: Benjamin Gaignard <[e-mail]>
>>>>> + *
>>>>> + * License terms:  GNU General Public License (GPL), version 2
>>>>> + */
>>>>> +
>>>>> +#include <linux/iio/iio.h>
>>>>> +#include <linux/iio/sysfs.h>
>>>>> +#include <linux/iio/timer/stm32-timer-trigger.h>
>>>>> +#include <linux/iio/trigger.h>
>>>>> +#include <linux/iio/triggered_event.h>
>>>>> +#include <linux/interrupt.h>
>>>>> +#include <linux/mfd/stm32-timers.h>
>>>>> +#include <linux/module.h>
>>>>> +#include <linux/platform_device.h>
>>>>> +
>>>>> +#define MAX_TRIGGERS 6
>>>>> +#define MAX_VALIDS 5
>>>>> +
>>>>> +/* List the triggers created by each timer */
>>>>> +static const void *triggers_table[][MAX_TRIGGERS] = {
>>>>> +     { TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
>>>>> +     { TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
>>>>> +     { TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
>>>>> +     { TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
>>>>> +     { TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
>>>>> +     { TIM6_TRGO,},
>>>>> +     { TIM7_TRGO,},
>>>>> +     { TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
>>>>> +     { TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
>>>>> +     { TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
>>>>> +};
>>>>> +
>>>>> +/* List the triggers accepted by each timer */
>>>>> +static const void *valids_table[][MAX_VALIDS] = {
>>>>> +     { TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
>>>>> +     { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
>>>>> +     { TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
>>>>> +     { TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
>>>>> +     { TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
>>>>> +     { }, /* timer 6 */
>>>>> +     { }, /* timer 7 */
>>>>> +     { TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
>>>>> +     { TIM2_TRGO, TIM3_TRGO,},
>>>>> +     { TIM4_TRGO, TIM5_TRGO,},
>>>>> +};
>>>>> +
>>>>> +struct stm32_timer_trigger {
>>>>> +     struct device *dev;
>>>>> +     struct regmap *regmap;
>>>>> +     struct clk *clk;
>>>>> +     u32 max_arr;
>>>>> +     const void *triggers;
>>>>> +     const void *valids;
>>>>> +};
>>>>> +
>>>>> +static int stm32_timer_start(struct stm32_timer_trigger *priv,
>>>>> +                          unsigned int frequency)
>>>>> +{
>>>>> +     unsigned long long prd, div;
>>>>> +     int prescaler = 0;
>>>>> +     u32 ccer, cr1;
>>>>> +
>>>>> +     /* Period and prescaler values depends of clock rate */
>>>>> +     div = (unsigned long long)clk_get_rate(priv->clk);
>>>>> +
>>>>> +     do_div(div, frequency);
>>>>> +
>>>>> +     prd = div;
>>>>> +
>>>>> +     /*
>>>>> +      * Increase prescaler value until we get a result that fit
>>>>> +      * with auto reload register maximum value.
>>>>> +      */
>>>>> +     while (div > priv->max_arr) {
>>>>> +             prescaler++;
>>>>> +             div = prd;
>>>>> +             do_div(div, (prescaler + 1));
>>>>> +     }
>>>>> +     prd = div;
>>>>> +
>>>>> +     if (prescaler > MAX_TIM_PSC) {
>>>>> +             dev_err(priv->dev, "prescaler exceeds the maximum value\n");
>>>>> +             return -EINVAL;
>>>>> +     }
>>>>> +
>>>>> +     /* Check if nobody else use the timer */
>>>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>>>> +     if (ccer & TIM_CCER_CCXE)
>>>>> +             return -EBUSY;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>> +     if (!(cr1 & TIM_CR1_CEN))
>>>>> +             clk_enable(priv->clk);
>>>>> +
>>>>> +     regmap_write(priv->regmap, TIM_PSC, prescaler);
>>>>> +     regmap_write(priv->regmap, TIM_ARR, prd - 1);
>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
>>>>> +
>>>>> +     /* Force master mode to update mode */
>>>>> +     regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
>>>>> +
>>>>> +     /* Make sure that registers are updated */
>>>>> +     regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
>>>>> +
>>>>> +     /* Enable controller */
>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
>>>>> +
>>>>> +     return 0;
>>>>> +}
>>>>> +
>>>>> +static void stm32_timer_stop(struct stm32_timer_trigger *priv)
>>>>> +{
>>>>> +     u32 ccer, cr1;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>>>> +     if (ccer & TIM_CCER_CCXE)
>>>>> +             return;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>> +     if (cr1 & TIM_CR1_CEN)
>>>>> +             clk_disable(priv->clk);
>>>>> +
>>>>> +     /* Stop timer */
>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
>>>>> +     regmap_write(priv->regmap, TIM_PSC, 0);
>>>>> +     regmap_write(priv->regmap, TIM_ARR, 0);
>>>>> +}
>>>>> +
>>>>> +static ssize_t stm32_tt_store_frequency(struct device *dev,
>>>>> +                                     struct device_attribute *attr,
>>>>> +                                     const char *buf, size_t len)
>>>>> +{
>>>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>>>>> +     unsigned int freq;
>>>>> +     int ret;
>>>>> +
>>>>> +     ret = kstrtouint(buf, 10, &freq);
>>>>> +     if (ret)
>>>>> +             return ret;
>>>>> +
>>>>> +     if (freq == 0) {
>>>>> +             stm32_timer_stop(priv);
>>>>> +     } else {
>>>>> +             ret = stm32_timer_start(priv, freq);
>>>>> +             if (ret)
>>>>> +                     return ret;
>>>>> +     }
>>>>> +
>>>>> +     return len;
>>>>> +}
>>>>> +
>>>>> +static ssize_t stm32_tt_read_frequency(struct device *dev,
>>>>> +                                    struct device_attribute *attr, char *buf)
>>>>> +{
>>>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
>>>>> +     u32 psc, arr, cr1;
>>>>> +     unsigned long long freq = 0;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>> +     regmap_read(priv->regmap, TIM_PSC, &psc);
>>>>> +     regmap_read(priv->regmap, TIM_ARR, &arr);
>>>>> +
>>>>> +     if (psc && arr && (cr1 & TIM_CR1_CEN)) {
>>>>> +             freq = (unsigned long long)clk_get_rate(priv->clk);
>>>>> +             do_div(freq, psc);
>>>>> +             do_div(freq, arr);
>>>>> +     }
>>>>> +
>>>>> +     return sprintf(buf, "%d\n", (unsigned int)freq);
>>>>> +}
>>>>> +
>>>>> +static IIO_DEV_ATTR_SAMP_FREQ(0660,
>>>>> +                           stm32_tt_read_frequency,
>>>>> +                           stm32_tt_store_frequency);
>>>>> +
>>>>> +static struct attribute *stm32_trigger_attrs[] = {
>>>>> +     &iio_dev_attr_sampling_frequency.dev_attr.attr,
>>>>> +     NULL,
>>>>> +};
>>>>> +
>>>>> +static const struct attribute_group stm32_trigger_attr_group = {
>>>>> +     .attrs = stm32_trigger_attrs,
>>>>> +};
>>>>> +
>>>>> +static const struct attribute_group *stm32_trigger_attr_groups[] = {
>>>>> +     &stm32_trigger_attr_group,
>>>>> +     NULL,
>>>>> +};
>>>>> +
>>>>> +static char *master_mode_table[] = {
>>>>> +     "reset",
>>>>> +     "enable",
>>>>> +     "update",
>>>>> +     "compare_pulse",
>>>>> +     "OC1REF",
>>>>> +     "OC2REF",
>>>>> +     "OC3REF",
>>>>> +     "OC4REF"
>>>>> +};
>>>>> +
>>>>> +static ssize_t stm32_tt_show_master_mode(struct device *dev,
>>>>> +                                      struct device_attribute *attr,
>>>>> +                                      char *buf)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     u32 cr2;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CR2, &cr2);
>>>>> +     cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
>>>>> +
>>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
>>>>> +}
>>>>> +
>>>>> +static ssize_t stm32_tt_store_master_mode(struct device *dev,
>>>>> +                                       struct device_attribute *attr,
>>>>> +                                       const char *buf, size_t len)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     int i;
>>>>> +
>>>>> +     for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
>>>>> +             if (!strncmp(master_mode_table[i], buf,
>>>>> +                          strlen(master_mode_table[i]))) {
>>>>> +                     regmap_update_bits(priv->regmap, TIM_CR2,
>>>>> +                                        TIM_CR2_MMS, i << TIM_CR2_MMS_SHIFT);
>>>>> +                     return len;
>>>>> +             }
>>>>> +     }
>>>>> +
>>>>> +     return -EINVAL;
>>>>> +}
>>>>> +
>>>>> +static IIO_CONST_ATTR(master_mode_available,
>>>>> +     "reset enable update compare_pulse OC1REF OC2REF OC3REF OC4REF");
>>>>> +
>>>>> +static IIO_DEVICE_ATTR(master_mode, 0660,
>>>>> +                    stm32_tt_show_master_mode,
>>>>> +                    stm32_tt_store_master_mode,
>>>>> +                    0);
>>>>> +
>>>>> +static char *slave_mode_table[] = {
>>>>> +     "disabled",
>>>>> +     "encoder_1",
>>>>> +     "encoder_2",
>>>>> +     "encoder_3",
>>>>> +     "reset",
>>>>> +     "gated",
>>>>> +     "trigger",
>>>>> +     "external_clock",
>>>>> +};
>>>>> +
>>>>> +static ssize_t stm32_tt_show_slave_mode(struct device *dev,
>>>>> +                                     struct device_attribute *attr,
>>>>> +                                     char *buf)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     u32 smcr;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_SMCR, &smcr);
>>>>> +     smcr &= TIM_SMCR_SMS;
>>>>> +
>>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
>>>>> +}
>>>>> +
>>>>> +static ssize_t stm32_tt_store_slave_mode(struct device *dev,
>>>>> +                                      struct device_attribute *attr,
>>>>> +                                      const char *buf, size_t len)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     int i;
>>>>> +
>>>>> +     for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
>>>>> +             if (!strncmp(slave_mode_table[i], buf,
>>>>> +                          strlen(slave_mode_table[i]))) {
>>>>> +                     regmap_update_bits(priv->regmap,
>>>>> +                                        TIM_SMCR, TIM_SMCR_SMS, i);
>>>>> +                     return len;
>>>>> +             }
>>>>> +     }
>>>>> +
>>>>> +     return -EINVAL;
>>>>> +}
>>>>> +
>>>>> +static IIO_CONST_ATTR(slave_mode_available,
>>>>> +"disabled encoder_1 encoder_2 encoder_3 reset gated trigger external_clock");
>>>>> +
>>>>> +static IIO_DEVICE_ATTR(slave_mode, 0660,
>>>>> +                    stm32_tt_show_slave_mode,
>>>>> +                    stm32_tt_store_slave_mode,
>>>>> +                    0);
>>>>> +
>>>>> +static struct attribute *stm32_timer_attrs[] = {
>>>>> +     &iio_dev_attr_master_mode.dev_attr.attr,
>>>>> +     &iio_const_attr_master_mode_available.dev_attr.attr,
>>>>> +     &iio_dev_attr_slave_mode.dev_attr.attr,
>>>>> +     &iio_const_attr_slave_mode_available.dev_attr.attr,
>>>>> +     NULL,
>>>>> +};
>>>>> +
>>>>> +static const struct attribute_group stm32_timer_attr_group = {
>>>>> +     .attrs = stm32_timer_attrs,
>>>>> +};
>>>>> +
>>>>> +static const struct iio_trigger_ops timer_trigger_ops = {
>>>>> +     .owner = THIS_MODULE,
>>>>> +};
>>>>> +
>>>>> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
>>>>> +{
>>>>> +     int ret;
>>>>> +     const char * const *cur = priv->triggers;
>>>>> +
>>>>> +     while (cur && *cur) {
>>>>> +             struct iio_trigger *trig;
>>>>> +
>>>>> +             trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur);
>>>>> +             if  (!trig)
>>>>> +                     return -ENOMEM;
>>>>> +
>>>>> +             trig->dev.parent = priv->dev->parent;
>>>>> +             trig->ops = &timer_trigger_ops;
>>>>> +             trig->dev.groups = stm32_trigger_attr_groups;
>>>>> +             iio_trigger_set_drvdata(trig, priv);
>>>>> +
>>>>> +             ret = devm_iio_trigger_register(priv->dev, trig);
>>>>> +             if (ret)
>>>>> +                     return ret;
>>>>> +             cur++;
>>>>> +     }
>>>>> +
>>>>> +     return 0;
>>>>> +}
>>>>> +
>>>>> +/**
>>>>> + * is_stm32_timer_trigger
>>>>> + * @trig: trigger to be checked
>>>>> + *
>>>>> + * return true if the trigger is a valid stm32 iio timer trigger
>>>>> + * either return false
>>>>> + */
>>>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig)
>>>>> +{
>>>>> +     return (trig->ops == &timer_trigger_ops);
>>>>> +}
>>>>> +EXPORT_SYMBOL(is_stm32_timer_trigger);
>>>>> +
>>>>> +static int stm32_validate_trigger(struct iio_dev *indio_dev,
>>>>> +                               struct iio_trigger *trig)
>>>>> +{
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     const char * const *cur = priv->valids;
>>>>> +     unsigned int i = 0;
>>>>> +
>>>>> +     if (!is_stm32_timer_trigger(trig))
>>>>> +             return -EINVAL;
>>>>> +
>>>>> +     while (cur && *cur) {
>>>>> +             if (!strncmp(trig->name, *cur, strlen(trig->name))) {
>>>>> +                     regmap_update_bits(priv->regmap,
>>>>> +                                        TIM_SMCR, TIM_SMCR_TS,
>>>>> +                                        i << TIM_SMCR_TS_SHIFT);
>>>>> +                     return 0;
>>>>> +             }
>>>>> +             cur++;
>>>>> +             i++;
>>>>> +     }
>>>>> +
>>>>> +     return -EINVAL;
>>>>> +}
>>>>> +
>>>>> +static const struct iio_info stm32_trigger_info = {
>>>>> +     .driver_module = THIS_MODULE,
>>>>> +     .validate_trigger = stm32_validate_trigger,
>>>>> +     .attrs = &stm32_timer_attr_group,
>>>>> +};
>>>>> +
>>>>> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev;
>>>>> +     int ret;
>>>>> +
>>>>> +     indio_dev = devm_iio_device_alloc(dev,
>>>>> +                                       sizeof(struct stm32_timer_trigger));
>>>>> +     if (!indio_dev)
>>>>> +             return NULL;
>>>>> +
>>>>> +     indio_dev->name = dev_name(dev);
>>>>> +     indio_dev->dev.parent = dev;
>>>>> +     indio_dev->info = &stm32_trigger_info;
>>>>> +     indio_dev->modes = INDIO_EVENT_TRIGGERED;
>>>>> +     indio_dev->num_channels = 0;
>>>>> +     indio_dev->dev.of_node = dev->of_node;
>>>>> +
>>>>> +     ret = devm_iio_device_register(dev, indio_dev);
>>>>> +     if (ret)
>>>>> +             return NULL;
>>>>> +
>>>>> +     return iio_priv(indio_dev);
>>>>> +}
>>>>> +
>>>>> +static int stm32_timer_trigger_probe(struct platform_device *pdev)
>>>>> +{
>>>>> +     struct device *dev = &pdev->dev;
>>>>> +     struct stm32_timer_trigger *priv;
>>>>> +     struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
>>>>> +     unsigned int index;
>>>>> +     int ret;
>>>>> +
>>>>> +     if (of_property_read_u32(dev->of_node, "reg", &index))
>>>>> +             return -EINVAL;
>>>>> +
>>>>> +     if (index >= ARRAY_SIZE(triggers_table))
>>>>> +             return -EINVAL;
>>>>> +
>>>>> +     /* Create an IIO device only if we have triggers to be validated */
>>>>> +     if (*valids_table[index])
>>>>> +             priv = stm32_setup_iio_device(dev);
>>>>
>>>> I still don't like this. Really feels like we shouldn't be creating an
>>>> iio device with all the bagage that carries just to allow us to do the
>>>> trigger trees.  We ought to have a much more light weight solution for this
>>>> functionality - we aren't typically even using the interrupt tree stuff
>>>> that the triggers for devices are all really about.
>>>>
>>>> A simpler approach of allowing each trigger the option of a parent seems like
>>>> it would be cleaner.  Could be done entirely within this driver in the first
>>>> instance.  Basically it would just look like your master and slave attributes
>>>> but have those under triggerX not iio:deviceX.
>>>>
>>>> We can work out how to make it more generic later - including perhaps the
>>>> option to trigger from triggers outside this driver, using some parallel
>>>> infrastructure to the device triggering.
>>>>
>>>>
>>>>> +     else
>>>>> +             priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>>>> +
>>>>> +     if (!priv)
>>>>> +             return -ENOMEM;
>>>>> +
>>>>> +     priv->dev = dev;
>>>>> +     priv->regmap = ddata->regmap;
>>>>> +     priv->clk = ddata->clk;
>>>>> +     priv->max_arr = ddata->max_arr;
>>>>> +     priv->triggers = triggers_table[index];
>>>>> +     priv->valids = valids_table[index];
>>>>> +
>>>>> +     ret = stm32_setup_iio_triggers(priv);
>>>>> +     if (ret)
>>>>> +             return ret;
>>>>> +
>>>>> +     platform_set_drvdata(pdev, priv);
>>>>> +
>>>>> +     return 0;
>>>>> +}
>>>>> +
>>>>> +static const struct of_device_id stm32_trig_of_match[] = {
>>>>> +     { .compatible = "st,stm32-timer-trigger", },
>>>>> +     { /* end node */ },
>>>>> +};
>>>>> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
>>>>> +
>>>>> +static struct platform_driver stm32_timer_trigger_driver = {
>>>>> +     .probe = stm32_timer_trigger_probe,
>>>>> +     .driver = {
>>>>> +             .name = "stm32-timer-trigger",
>>>>> +             .of_match_table = stm32_trig_of_match,
>>>>> +     },
>>>>> +};
>>>>> +module_platform_driver(stm32_timer_trigger_driver);
>>>>> +
>>>>> +MODULE_ALIAS("platform: stm32-timer-trigger");
>>>>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger driver");
>>>>> +MODULE_LICENSE("GPL v2");
>>>>> diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
>>>>> index 809b2e7..f2af4fe 100644
>>>>> --- a/drivers/iio/trigger/Kconfig
>>>>> +++ b/drivers/iio/trigger/Kconfig
>>>>> @@ -46,5 +46,4 @@ config IIO_SYSFS_TRIGGER
>>>>>
>>>>>         To compile this driver as a module, choose M here: the
>>>>>         module will be called iio-trig-sysfs.
>>>>> -
>>>> Clean this up.
>>>
>>> ok
>>>
>>>>>  endmenu
>>>>> diff --git a/include/linux/iio/timer/stm32-timer-trigger.h b/include/linux/iio/timer/stm32-timer-trigger.h
>>>>> new file mode 100644
>>>>> index 0000000..55535ae
>>>>> --- /dev/null
>>>>> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
>>>>> @@ -0,0 +1,62 @@
>>>>> +/*
>>>>> + * Copyright (C) STMicroelectronics 2016
>>>>> + *
>>>>> + * Author: Benjamin Gaignard <[e-mail]>
>>>>> + *
>>>>> + * License terms:  GNU General Public License (GPL), version 2
>>>>> + */
>>>>> +
>>>>> +#ifndef _STM32_TIMER_TRIGGER_H_
>>>>> +#define _STM32_TIMER_TRIGGER_H_
>>>>> +
>>>>> +#define TIM1_TRGO    "tim1_trgo"
>>>>> +#define TIM1_CH1     "tim1_ch1"
>>>>> +#define TIM1_CH2     "tim1_ch2"
>>>>> +#define TIM1_CH3     "tim1_ch3"
>>>>> +#define TIM1_CH4     "tim1_ch4"
>>>>> +
>>>>> +#define TIM2_TRGO    "tim2_trgo"
>>>>> +#define TIM2_CH1     "tim2_ch1"
>>>>> +#define TIM2_CH2     "tim2_ch2"
>>>>> +#define TIM2_CH3     "tim2_ch3"
>>>>> +#define TIM2_CH4     "tim2_ch4"
>>>>> +
>>>>> +#define TIM3_TRGO    "tim3_trgo"
>>>>> +#define TIM3_CH1     "tim3_ch1"
>>>>> +#define TIM3_CH2     "tim3_ch2"
>>>>> +#define TIM3_CH3     "tim3_ch3"
>>>>> +#define TIM3_CH4     "tim3_ch4"
>>>>> +
>>>>> +#define TIM4_TRGO    "tim4_trgo"
>>>>> +#define TIM4_CH1     "tim4_ch1"
>>>>> +#define TIM4_CH2     "tim4_ch2"
>>>>> +#define TIM4_CH3     "tim4_ch3"
>>>>> +#define TIM4_CH4     "tim4_ch4"
>>>>> +
>>>>> +#define TIM5_TRGO    "tim5_trgo"
>>>>> +#define TIM5_CH1     "tim5_ch1"
>>>>> +#define TIM5_CH2     "tim5_ch2"
>>>>> +#define TIM5_CH3     "tim5_ch3"
>>>>> +#define TIM5_CH4     "tim5_ch4"
>>>>> +
>>>>> +#define TIM6_TRGO    "tim6_trgo"
>>>>> +
>>>>> +#define TIM7_TRGO    "tim7_trgo"
>>>>> +
>>>>> +#define TIM8_TRGO    "tim8_trgo"
>>>>> +#define TIM8_CH1     "tim8_ch1"
>>>>> +#define TIM8_CH2     "tim8_ch2"
>>>>> +#define TIM8_CH3     "tim8_ch3"
>>>>> +#define TIM8_CH4     "tim8_ch4"
>>>>> +
>>>>> +#define TIM9_TRGO    "tim9_trgo"
>>>>> +#define TIM9_CH1     "tim9_ch1"
>>>>> +#define TIM9_CH2     "tim9_ch2"
>>>>> +
>>>>> +#define TIM12_TRGO   "tim12_trgo"
>>>>> +#define TIM12_CH1    "tim12_ch1"
>>>>> +#define TIM12_CH2    "tim12_ch2"
>>>>> +
>>>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
>>>>> +
>>>>> +#endif
>>>>>
>>>>
>>>
>>>
>>>
>>
>
>
>
> --
> Benjamin Gaignard
>
> Graphic Study Group
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Jonathan Cameron Jan. 3, 2017, 5:16 p.m. UTC | #6

On 3 January 2017 09:23:34 GMT+00:00, Benjamin Gaignard <[e-mail]> wrote:
>2017-01-02 19:22 GMT+01:00 Jonathan Cameron <[e-mail]>:
>> On 02/01/17 08:46, Benjamin Gaignard wrote:
>>> 2016-12-30 22:12 GMT+01:00 Jonathan Cameron <[e-mail]>:
>>>> On 09/12/16 14:15, Benjamin Gaignard wrote:
>>>>> Timers IPs can be used to generate triggers for other IPs like
>>>>> DAC, ADC or other timers.
>>>>> Each trigger may result of timer internals signals like counter
>enable,
>>>>> reset or edge, this configuration could be done through
>"master_mode"
>>>>> device attribute.
>>>>>
>>>>> A timer device could be triggered by other timers, we use the
>trigger
>>>>> name and is_stm32_iio_timer_trigger() function to distinguish them
>>>>> and configure IP input switch.
>>>>>
>>>>> Timer may also decide on which event (edge, level) they could
>>>>> be activated by a trigger, this configuration is done by writing
>in
>>>>> "slave_mode" device attribute.
>>>>>
>>>>> Since triggers could also be used by DAC or ADC their names are
>defined
>>>>> in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will
>be able
>>>>> to configure themselves in valid_trigger function
>>>>>
>>>>> Trigger have a "sampling_frequency" attribute which allow to
>configure
>>>>> timer sampling frequency without using PWM interface
>>>>>
>>>>> version 5:
>>>>> - simplify tables of triggers
>>>>> - only create an IIO device when needed
>>>>>
>>>>> version 4:
>>>>> - get triggers configuration from "reg" in DT
>>>>> - add tables of triggers
>>>>> - sampling frequency is enable/disable when writing in trigger
>>>>>   sampling_frequency attribute
>>>>> - no more use of interruptions
>>>>>
>>>>> version 3:
>>>>> - change compatible to "st,stm32-timer-trigger"
>>>>> - fix attributes access right
>>>>> - use string instead of int for master_mode and slave_mode
>>>>> - document device attributes in sysfs-bus-iio-timer-stm32
>>>>>
>>>>> version 2:
>>>>> - keep only one compatible
>>>>> - use st,input-triggers-names and st,output-triggers-names
>>>>>   to know which triggers are accepted and/or create by the device
>>>> Firstly, sorry it has taken me so long to get back to this.
>>>>
>>>> I'm still not keen on this use of iio_device elements just to act
>as
>>>> glue between triggers.  I think we need to work out a more light
>weight
>>>> way to do this.  As you are only using them for validation and to
>provide
>>>> somewhere to hang the control attibutes off, there is nothing
>stopping us
>>>> moving that over to the iio_trigger instead which would avoid the
>messy
>>>> duality going on here.
>>>
>>> I have add an iio_device because each hardware can generate multiple
>>> triggers (up to 5: trgo, ch 1...4) and slave_mode attribute will
>impact all the
>>> triggers of a device. For me it was making sense to centralize that
>in an
>>> iio_device rather than having an attribute "shared" (from hardware
>>> point of view)
>>> on multiple triggers.
>>> Since master_mode attribute is only used by trgo and not impact
>ch1...4
>>> triggers I will move it to trigger instead of the iio_device.
>>>
>>> I also wanted to be able to connect triggers on a iio_device as I
>>> could do for an
>>> ADC with a command like 'echo "tim1_trgo" >
>iio_deviceX/trigger/current_trigger'
>> This is interesting, but with a bit of refactoring I would think it
>would
>> be possible to share some of that code thus allowing non IIO devices
>to
>> bind to triggers.  Ultimately I want to be able to bind a trigger to
>> a trigger - I appreciate here the topology is more limited than that
>> so some complexity comes in.
>>
>> My gut feeling is that representing that topology explicitly is hard
>> to do in a remotely general way, but lets try it and see.
>> We run into this sort of interdependency issue between different bits
>of
>> the hardware all the time.  Setting a value somewhere effects the
>configuration
>> elsewhere - often the best plan is to just let that happen and leave
>it up to
>> userspace to check for changes if it cares.
>
>okay
>
>>> If I change that to parent_trigger attribute it change this behavior
>>> and I will have to
>>> duplicated what is done in iio_trigger_write_current() to find and
>>> validate triggers.
>> I get the reasoning, but we still end up with something represented
>> by an IIO device that isn't providing any channels at all. It's
>simply
>> using some of the infrastructure.  To my mind it is 'something else'
>> and should be represented as such.  I have no problem at all with
>> you registering additional elements in /sysfs/bus/iio/ to represent
>> these shared elements - we already have drivers that do that to
>> provide some centralized infrastructure (e.g. the sysfs-trigger)
>
>My hardware block are timers maybe I can add a channel type "IIO_TIMER"
>and declare a channel with info_mask_separate =
>BIT(IIO_CHAN_INFO_SAMP_FREQ)
>so I will be able to write/read sampling frequency on IIO device.
Hmm stretching a point. There aren't really input or output channels. 

Still not convinced there should be any IIO devices near this at all.
>
>> I'm worried about the scope spread we get for an IIO device
>otherwise.
>> They serve a well defined purpose at the moment, and that isn't what
>> is happening here.
>>
>> So my gut feeling is we are better deliberately not representing the
>> inter dependence and claiming all triggers we are creating are
>> independent.  That way we can have a nice generic infrastructure
>> that will work in all cases (be it pushing the sanity checking to
>> userspace).
>>
>> So each trigger has direct access to what controls it.  Changing
>anything
>> can effect other triggers in weird ways.
>>
>> I'm finding it hard to see anything else generalizing sufficiently
>> as we'll always get cases where we can't represent the topology
>without
>> diving into the complexity of something like the media controller
>> framework.
>>
>> Jonathan
>>>
>>>> I might still be missing something though!
>>>>
>>>> You would only I think need 3 attributes
>>>>
>>>> parrent_trigger
>>>> and something like your master_mode and slave_mode attributes.
>>>>
>>>> The parrent_trigger would need some validation etc, but if we keep
>it
>>>> within this driver initially that won't be hard to do. Checking the
>device
>>>> parent matches will do most of it.
>>>>
>>>> Jonathan
>>>>>
>>>>> Signed-off-by: Benjamin Gaignard <[e-mail]>
>>>>> ---
>>>>>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
>>>>>  drivers/iio/Kconfig                                |   2 +-
>>>>>  drivers/iio/Makefile                               |   1 +
>>>>>  drivers/iio/timer/Kconfig                          |  13 +
>>>>>  drivers/iio/timer/Makefile                         |   1 +
>>>>>  drivers/iio/timer/stm32-timer-trigger.c            | 466
>+++++++++++++++++++++
>>>>>  drivers/iio/trigger/Kconfig                        |   1 -
>>>>>  include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
>>>>>  8 files changed, 599 insertions(+), 2 deletions(-)
>>>>>  create mode 100644
>Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>>  create mode 100644 drivers/iio/timer/Kconfig
>>>>>  create mode 100644 drivers/iio/timer/Makefile
>>>>>  create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
>>>>>  create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h
>>>>>
>>>>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>> new file mode 100644
>>>>> index 0000000..26583dd
>>>>> --- /dev/null
>>>>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>> @@ -0,0 +1,55 @@
>>>>> +What:               
>/sys/bus/iio/devices/iio:deviceX/master_mode_available
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the list possible master modes which
>are:
>>>>> +             - "reset"     : The UG bit from the TIMx_EGR
>register is used as trigger output (TRGO).
>>>>> +             - "enable"    : The Counter Enable signal CNT_EN is
>used as trigger output.
>>>>> +             - "update"    : The update event is selected as
>trigger output.
>>>>> +                             For instance a master timer can then
>be used as a prescaler for a slave timer.
>>>>> +             - "compare_pulse" : The trigger output send a
>positive pulse when the CC1IF flag is to be set.
>>>>> +             - "OC1REF"    : OC1REF signal is used as trigger
>output.
>>>>> +             - "OC2REF"    : OC2REF signal is used as trigger
>output.
>>>>> +             - "OC3REF"    : OC3REF signal is used as trigger
>output.
>>>>> +             - "OC4REF"    : OC4REF signal is used as trigger
>output.
>>>>> +
>>>>> +What:                /sys/bus/iio/devices/iio:deviceX/master_mode
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the current master modes.
>>>>> +             Writing set the master mode
>>>>> +
>>>>> +What:               
>/sys/bus/iio/devices/iio:deviceX/slave_mode_available
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the list possible slave modes which
>are:
>>>>> +             - "disabled"  : The prescaler is clocked directly by
>the internal clock.
>>>>> +             - "encoder_1" : Counter counts up/down on TI2FP1
>edge depending on TI1FP2 level.
>>>>> +             - "encoder_2" : Counter counts up/down on TI1FP2
>edge depending on TI2FP1 level.
>>>>> +             - "encoder_3" : Counter counts up/down on both
>TI1FP1 and TI2FP2 edges depending
>>>>> +                             on the level of the other input.
>>>>> +             - "reset"     : Rising edge of the selected trigger
>input reinitializes the counter
>>>>> +                             and generates an update of the
>registers.
>>>>> +             - "gated"     : The counter clock is enabled when
>the trigger input is high.
>>>>> +                             The counter stops (but is not reset)
>as soon as the trigger becomes low.
>>>>> +                             Both start and stop of the counter
>are controlled.
>>>>> +             - "trigger"   : The counter starts at a rising edge
>of the trigger TRGI (but it is not
>>>>> +                             reset). Only the start of the
>counter is controlled.
>>>>> +             - "external_clock": Rising edges of the selected
>trigger (TRGI) clock the counter.
>>>>> +
>>>>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the current slave mode.
>>>>> +             Writing set the slave mode
>>>>> +
>>>>> +What:               
>/sys/bus/iio/devices/triggerX/sampling_frequency
>>>>> +KernelVersion:       4.10
>>>>> +Contact:     [e-mail]
>>>>> +Description:
>>>>> +             Reading returns the current sampling frequency.
>>>>> +             Writing an value different of 0 set and start
>sampling.
>>>>> +             Writing 0 stop sampling.
>>>>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>>>>> index 6743b18..2de2a80 100644
>>>>> --- a/drivers/iio/Kconfig
>>>>> +++ b/drivers/iio/Kconfig
>>>>> @@ -90,5 +90,5 @@ source "drivers/iio/potentiometer/Kconfig"
>>>>>  source "drivers/iio/pressure/Kconfig"
>>>>>  source "drivers/iio/proximity/Kconfig"
>>>>>  source "drivers/iio/temperature/Kconfig"
>>>>> -
>>>>> +source "drivers/iio/timer/Kconfig"
>>>>>  endif # IIO
>>>>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>>>>> index 87e4c43..b797c08 100644
>>>>> --- a/drivers/iio/Makefile
>>>>> +++ b/drivers/iio/Makefile
>>>>> @@ -32,4 +32,5 @@ obj-y += potentiometer/
>>>>>  obj-y += pressure/
>>>>>  obj-y += proximity/
>>>>>  obj-y += temperature/
>>>>> +obj-y += timer/
>>>>>  obj-y += trigger/
>>>>> diff --git a/drivers/iio/timer/Kconfig b/drivers/iio/timer/Kconfig
>>>>> new file mode 100644
>>>>> index 0000000..e3c21f2
>>>>> --- /dev/null
>>>>> +++ b/drivers/iio/timer/Kconfig
>>>>> @@ -0,0 +1,13 @@
>>>>> +#
>>>>> +# Timers drivers
>>>>> +
>>>>> +menu "Timers"
>>>>> +
>>>>> +config IIO_STM32_TIMER_TRIGGER
>>>>> +     tristate "STM32 Timer Trigger"
>>>>> +     depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) ||
>COMPILE_TEST
>>>>> +     select IIO_TRIGGERED_EVENT
>>>>> +     help
>>>>> +       Select this option to enable STM32 Timer Trigger
>>>>> +
>>>>> +endmenu
>>>>> diff --git a/drivers/iio/timer/Makefile
>b/drivers/iio/timer/Makefile
>>>>> new file mode 100644
>>>>> index 0000000..4ad95ec9
>>>>> --- /dev/null
>>>>> +++ b/drivers/iio/timer/Makefile
>>>>> @@ -0,0 +1 @@
>>>>> +obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
>>>>> diff --git a/drivers/iio/timer/stm32-timer-trigger.c
>b/drivers/iio/timer/stm32-timer-trigger.c
>>>>> new file mode 100644
>>>>> index 0000000..8d16e8f
>>>>> --- /dev/null
>>>>> +++ b/drivers/iio/timer/stm32-timer-trigger.c
>>>>> @@ -0,0 +1,466 @@
>>>>> +/*
>>>>> + * Copyright (C) STMicroelectronics 2016
>>>>> + *
>>>>> + * Author: Benjamin Gaignard <[e-mail]>
>>>>> + *
>>>>> + * License terms:  GNU General Public License (GPL), version 2
>>>>> + */
>>>>> +
>>>>> +#include <linux/iio/iio.h>
>>>>> +#include <linux/iio/sysfs.h>
>>>>> +#include <linux/iio/timer/stm32-timer-trigger.h>
>>>>> +#include <linux/iio/trigger.h>
>>>>> +#include <linux/iio/triggered_event.h>
>>>>> +#include <linux/interrupt.h>
>>>>> +#include <linux/mfd/stm32-timers.h>
>>>>> +#include <linux/module.h>
>>>>> +#include <linux/platform_device.h>
>>>>> +
>>>>> +#define MAX_TRIGGERS 6
>>>>> +#define MAX_VALIDS 5
>>>>> +
>>>>> +/* List the triggers created by each timer */
>>>>> +static const void *triggers_table[][MAX_TRIGGERS] = {
>>>>> +     { TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
>>>>> +     { TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
>>>>> +     { TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
>>>>> +     { TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
>>>>> +     { TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
>>>>> +     { TIM6_TRGO,},
>>>>> +     { TIM7_TRGO,},
>>>>> +     { TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
>>>>> +     { TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
>>>>> +     { TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
>>>>> +};
>>>>> +
>>>>> +/* List the triggers accepted by each timer */
>>>>> +static const void *valids_table[][MAX_VALIDS] = {
>>>>> +     { TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
>>>>> +     { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
>>>>> +     { TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
>>>>> +     { TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
>>>>> +     { TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
>>>>> +     { }, /* timer 6 */
>>>>> +     { }, /* timer 7 */
>>>>> +     { TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
>>>>> +     { TIM2_TRGO, TIM3_TRGO,},
>>>>> +     { TIM4_TRGO, TIM5_TRGO,},
>>>>> +};
>>>>> +
>>>>> +struct stm32_timer_trigger {
>>>>> +     struct device *dev;
>>>>> +     struct regmap *regmap;
>>>>> +     struct clk *clk;
>>>>> +     u32 max_arr;
>>>>> +     const void *triggers;
>>>>> +     const void *valids;
>>>>> +};
>>>>> +
>>>>> +static int stm32_timer_start(struct stm32_timer_trigger *priv,
>>>>> +                          unsigned int frequency)
>>>>> +{
>>>>> +     unsigned long long prd, div;
>>>>> +     int prescaler = 0;
>>>>> +     u32 ccer, cr1;
>>>>> +
>>>>> +     /* Period and prescaler values depends of clock rate */
>>>>> +     div = (unsigned long long)clk_get_rate(priv->clk);
>>>>> +
>>>>> +     do_div(div, frequency);
>>>>> +
>>>>> +     prd = div;
>>>>> +
>>>>> +     /*
>>>>> +      * Increase prescaler value until we get a result that fit
>>>>> +      * with auto reload register maximum value.
>>>>> +      */
>>>>> +     while (div > priv->max_arr) {
>>>>> +             prescaler++;
>>>>> +             div = prd;
>>>>> +             do_div(div, (prescaler + 1));
>>>>> +     }
>>>>> +     prd = div;
>>>>> +
>>>>> +     if (prescaler > MAX_TIM_PSC) {
>>>>> +             dev_err(priv->dev, "prescaler exceeds the maximum
>value\n");
>>>>> +             return -EINVAL;
>>>>> +     }
>>>>> +
>>>>> +     /* Check if nobody else use the timer */
>>>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>>>> +     if (ccer & TIM_CCER_CCXE)
>>>>> +             return -EBUSY;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>> +     if (!(cr1 & TIM_CR1_CEN))
>>>>> +             clk_enable(priv->clk);
>>>>> +
>>>>> +     regmap_write(priv->regmap, TIM_PSC, prescaler);
>>>>> +     regmap_write(priv->regmap, TIM_ARR, prd - 1);
>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE,
>TIM_CR1_ARPE);
>>>>> +
>>>>> +     /* Force master mode to update mode */
>>>>> +     regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS,
>0x20);
>>>>> +
>>>>> +     /* Make sure that registers are updated */
>>>>> +     regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG,
>TIM_EGR_UG);
>>>>> +
>>>>> +     /* Enable controller */
>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN,
>TIM_CR1_CEN);
>>>>> +
>>>>> +     return 0;
>>>>> +}
>>>>> +
>>>>> +static void stm32_timer_stop(struct stm32_timer_trigger *priv)
>>>>> +{
>>>>> +     u32 ccer, cr1;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>>>> +     if (ccer & TIM_CCER_CCXE)
>>>>> +             return;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>> +     if (cr1 & TIM_CR1_CEN)
>>>>> +             clk_disable(priv->clk);
>>>>> +
>>>>> +     /* Stop timer */
>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
>>>>> +     regmap_write(priv->regmap, TIM_PSC, 0);
>>>>> +     regmap_write(priv->regmap, TIM_ARR, 0);
>>>>> +}
>>>>> +
>>>>> +static ssize_t stm32_tt_store_frequency(struct device *dev,
>>>>> +                                     struct device_attribute
>*attr,
>>>>> +                                     const char *buf, size_t len)
>>>>> +{
>>>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>>>> +     struct stm32_timer_trigger *priv =
>iio_trigger_get_drvdata(trig);
>>>>> +     unsigned int freq;
>>>>> +     int ret;
>>>>> +
>>>>> +     ret = kstrtouint(buf, 10, &freq);
>>>>> +     if (ret)
>>>>> +             return ret;
>>>>> +
>>>>> +     if (freq == 0) {
>>>>> +             stm32_timer_stop(priv);
>>>>> +     } else {
>>>>> +             ret = stm32_timer_start(priv, freq);
>>>>> +             if (ret)
>>>>> +                     return ret;
>>>>> +     }
>>>>> +
>>>>> +     return len;
>>>>> +}
>>>>> +
>>>>> +static ssize_t stm32_tt_read_frequency(struct device *dev,
>>>>> +                                    struct device_attribute
>*attr, char *buf)
>>>>> +{
>>>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>>>> +     struct stm32_timer_trigger *priv =
>iio_trigger_get_drvdata(trig);
>>>>> +     u32 psc, arr, cr1;
>>>>> +     unsigned long long freq = 0;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>> +     regmap_read(priv->regmap, TIM_PSC, &psc);
>>>>> +     regmap_read(priv->regmap, TIM_ARR, &arr);
>>>>> +
>>>>> +     if (psc && arr && (cr1 & TIM_CR1_CEN)) {
>>>>> +             freq = (unsigned long long)clk_get_rate(priv->clk);
>>>>> +             do_div(freq, psc);
>>>>> +             do_div(freq, arr);
>>>>> +     }
>>>>> +
>>>>> +     return sprintf(buf, "%d\n", (unsigned int)freq);
>>>>> +}
>>>>> +
>>>>> +static IIO_DEV_ATTR_SAMP_FREQ(0660,
>>>>> +                           stm32_tt_read_frequency,
>>>>> +                           stm32_tt_store_frequency);
>>>>> +
>>>>> +static struct attribute *stm32_trigger_attrs[] = {
>>>>> +     &iio_dev_attr_sampling_frequency.dev_attr.attr,
>>>>> +     NULL,
>>>>> +};
>>>>> +
>>>>> +static const struct attribute_group stm32_trigger_attr_group = {
>>>>> +     .attrs = stm32_trigger_attrs,
>>>>> +};
>>>>> +
>>>>> +static const struct attribute_group *stm32_trigger_attr_groups[]
>= {
>>>>> +     &stm32_trigger_attr_group,
>>>>> +     NULL,
>>>>> +};
>>>>> +
>>>>> +static char *master_mode_table[] = {
>>>>> +     "reset",
>>>>> +     "enable",
>>>>> +     "update",
>>>>> +     "compare_pulse",
>>>>> +     "OC1REF",
>>>>> +     "OC2REF",
>>>>> +     "OC3REF",
>>>>> +     "OC4REF"
>>>>> +};
>>>>> +
>>>>> +static ssize_t stm32_tt_show_master_mode(struct device *dev,
>>>>> +                                      struct device_attribute
>*attr,
>>>>> +                                      char *buf)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     u32 cr2;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_CR2, &cr2);
>>>>> +     cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
>>>>> +
>>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n",
>master_mode_table[cr2]);
>>>>> +}
>>>>> +
>>>>> +static ssize_t stm32_tt_store_master_mode(struct device *dev,
>>>>> +                                       struct device_attribute
>*attr,
>>>>> +                                       const char *buf, size_t
>len)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     int i;
>>>>> +
>>>>> +     for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
>>>>> +             if (!strncmp(master_mode_table[i], buf,
>>>>> +                          strlen(master_mode_table[i]))) {
>>>>> +                     regmap_update_bits(priv->regmap, TIM_CR2,
>>>>> +                                        TIM_CR2_MMS, i <<
>TIM_CR2_MMS_SHIFT);
>>>>> +                     return len;
>>>>> +             }
>>>>> +     }
>>>>> +
>>>>> +     return -EINVAL;
>>>>> +}
>>>>> +
>>>>> +static IIO_CONST_ATTR(master_mode_available,
>>>>> +     "reset enable update compare_pulse OC1REF OC2REF OC3REF
>OC4REF");
>>>>> +
>>>>> +static IIO_DEVICE_ATTR(master_mode, 0660,
>>>>> +                    stm32_tt_show_master_mode,
>>>>> +                    stm32_tt_store_master_mode,
>>>>> +                    0);
>>>>> +
>>>>> +static char *slave_mode_table[] = {
>>>>> +     "disabled",
>>>>> +     "encoder_1",
>>>>> +     "encoder_2",
>>>>> +     "encoder_3",
>>>>> +     "reset",
>>>>> +     "gated",
>>>>> +     "trigger",
>>>>> +     "external_clock",
>>>>> +};
>>>>> +
>>>>> +static ssize_t stm32_tt_show_slave_mode(struct device *dev,
>>>>> +                                     struct device_attribute
>*attr,
>>>>> +                                     char *buf)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     u32 smcr;
>>>>> +
>>>>> +     regmap_read(priv->regmap, TIM_SMCR, &smcr);
>>>>> +     smcr &= TIM_SMCR_SMS;
>>>>> +
>>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n",
>slave_mode_table[smcr]);
>>>>> +}
>>>>> +
>>>>> +static ssize_t stm32_tt_store_slave_mode(struct device *dev,
>>>>> +                                      struct device_attribute
>*attr,
>>>>> +                                      const char *buf, size_t
>len)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     int i;
>>>>> +
>>>>> +     for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
>>>>> +             if (!strncmp(slave_mode_table[i], buf,
>>>>> +                          strlen(slave_mode_table[i]))) {
>>>>> +                     regmap_update_bits(priv->regmap,
>>>>> +                                        TIM_SMCR, TIM_SMCR_SMS,
>i);
>>>>> +                     return len;
>>>>> +             }
>>>>> +     }
>>>>> +
>>>>> +     return -EINVAL;
>>>>> +}
>>>>> +
>>>>> +static IIO_CONST_ATTR(slave_mode_available,
>>>>> +"disabled encoder_1 encoder_2 encoder_3 reset gated trigger
>external_clock");
>>>>> +
>>>>> +static IIO_DEVICE_ATTR(slave_mode, 0660,
>>>>> +                    stm32_tt_show_slave_mode,
>>>>> +                    stm32_tt_store_slave_mode,
>>>>> +                    0);
>>>>> +
>>>>> +static struct attribute *stm32_timer_attrs[] = {
>>>>> +     &iio_dev_attr_master_mode.dev_attr.attr,
>>>>> +     &iio_const_attr_master_mode_available.dev_attr.attr,
>>>>> +     &iio_dev_attr_slave_mode.dev_attr.attr,
>>>>> +     &iio_const_attr_slave_mode_available.dev_attr.attr,
>>>>> +     NULL,
>>>>> +};
>>>>> +
>>>>> +static const struct attribute_group stm32_timer_attr_group = {
>>>>> +     .attrs = stm32_timer_attrs,
>>>>> +};
>>>>> +
>>>>> +static const struct iio_trigger_ops timer_trigger_ops = {
>>>>> +     .owner = THIS_MODULE,
>>>>> +};
>>>>> +
>>>>> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger
>*priv)
>>>>> +{
>>>>> +     int ret;
>>>>> +     const char * const *cur = priv->triggers;
>>>>> +
>>>>> +     while (cur && *cur) {
>>>>> +             struct iio_trigger *trig;
>>>>> +
>>>>> +             trig = devm_iio_trigger_alloc(priv->dev, "%s",
>*cur);
>>>>> +             if  (!trig)
>>>>> +                     return -ENOMEM;
>>>>> +
>>>>> +             trig->dev.parent = priv->dev->parent;
>>>>> +             trig->ops = &timer_trigger_ops;
>>>>> +             trig->dev.groups = stm32_trigger_attr_groups;
>>>>> +             iio_trigger_set_drvdata(trig, priv);
>>>>> +
>>>>> +             ret = devm_iio_trigger_register(priv->dev, trig);
>>>>> +             if (ret)
>>>>> +                     return ret;
>>>>> +             cur++;
>>>>> +     }
>>>>> +
>>>>> +     return 0;
>>>>> +}
>>>>> +
>>>>> +/**
>>>>> + * is_stm32_timer_trigger
>>>>> + * @trig: trigger to be checked
>>>>> + *
>>>>> + * return true if the trigger is a valid stm32 iio timer trigger
>>>>> + * either return false
>>>>> + */
>>>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig)
>>>>> +{
>>>>> +     return (trig->ops == &timer_trigger_ops);
>>>>> +}
>>>>> +EXPORT_SYMBOL(is_stm32_timer_trigger);
>>>>> +
>>>>> +static int stm32_validate_trigger(struct iio_dev *indio_dev,
>>>>> +                               struct iio_trigger *trig)
>>>>> +{
>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>> +     const char * const *cur = priv->valids;
>>>>> +     unsigned int i = 0;
>>>>> +
>>>>> +     if (!is_stm32_timer_trigger(trig))
>>>>> +             return -EINVAL;
>>>>> +
>>>>> +     while (cur && *cur) {
>>>>> +             if (!strncmp(trig->name, *cur, strlen(trig->name)))
>{
>>>>> +                     regmap_update_bits(priv->regmap,
>>>>> +                                        TIM_SMCR, TIM_SMCR_TS,
>>>>> +                                        i << TIM_SMCR_TS_SHIFT);
>>>>> +                     return 0;
>>>>> +             }
>>>>> +             cur++;
>>>>> +             i++;
>>>>> +     }
>>>>> +
>>>>> +     return -EINVAL;
>>>>> +}
>>>>> +
>>>>> +static const struct iio_info stm32_trigger_info = {
>>>>> +     .driver_module = THIS_MODULE,
>>>>> +     .validate_trigger = stm32_validate_trigger,
>>>>> +     .attrs = &stm32_timer_attr_group,
>>>>> +};
>>>>> +
>>>>> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct
>device *dev)
>>>>> +{
>>>>> +     struct iio_dev *indio_dev;
>>>>> +     int ret;
>>>>> +
>>>>> +     indio_dev = devm_iio_device_alloc(dev,
>>>>> +                                       sizeof(struct
>stm32_timer_trigger));
>>>>> +     if (!indio_dev)
>>>>> +             return NULL;
>>>>> +
>>>>> +     indio_dev->name = dev_name(dev);
>>>>> +     indio_dev->dev.parent = dev;
>>>>> +     indio_dev->info = &stm32_trigger_info;
>>>>> +     indio_dev->modes = INDIO_EVENT_TRIGGERED;
>>>>> +     indio_dev->num_channels = 0;
>>>>> +     indio_dev->dev.of_node = dev->of_node;
>>>>> +
>>>>> +     ret = devm_iio_device_register(dev, indio_dev);
>>>>> +     if (ret)
>>>>> +             return NULL;
>>>>> +
>>>>> +     return iio_priv(indio_dev);
>>>>> +}
>>>>> +
>>>>> +static int stm32_timer_trigger_probe(struct platform_device
>*pdev)
>>>>> +{
>>>>> +     struct device *dev = &pdev->dev;
>>>>> +     struct stm32_timer_trigger *priv;
>>>>> +     struct stm32_timers *ddata =
>dev_get_drvdata(pdev->dev.parent);
>>>>> +     unsigned int index;
>>>>> +     int ret;
>>>>> +
>>>>> +     if (of_property_read_u32(dev->of_node, "reg", &index))
>>>>> +             return -EINVAL;
>>>>> +
>>>>> +     if (index >= ARRAY_SIZE(triggers_table))
>>>>> +             return -EINVAL;
>>>>> +
>>>>> +     /* Create an IIO device only if we have triggers to be
>validated */
>>>>> +     if (*valids_table[index])
>>>>> +             priv = stm32_setup_iio_device(dev);
>>>>
>>>> I still don't like this. Really feels like we shouldn't be creating
>an
>>>> iio device with all the bagage that carries just to allow us to do
>the
>>>> trigger trees.  We ought to have a much more light weight solution
>for this
>>>> functionality - we aren't typically even using the interrupt tree
>stuff
>>>> that the triggers for devices are all really about.
>>>>
>>>> A simpler approach of allowing each trigger the option of a parent
>seems like
>>>> it would be cleaner.  Could be done entirely within this driver in
>the first
>>>> instance.  Basically it would just look like your master and slave
>attributes
>>>> but have those under triggerX not iio:deviceX.
>>>>
>>>> We can work out how to make it more generic later - including
>perhaps the
>>>> option to trigger from triggers outside this driver, using some
>parallel
>>>> infrastructure to the device triggering.
>>>>
>>>>
>>>>> +     else
>>>>> +             priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>>>> +
>>>>> +     if (!priv)
>>>>> +             return -ENOMEM;
>>>>> +
>>>>> +     priv->dev = dev;
>>>>> +     priv->regmap = ddata->regmap;
>>>>> +     priv->clk = ddata->clk;
>>>>> +     priv->max_arr = ddata->max_arr;
>>>>> +     priv->triggers = triggers_table[index];
>>>>> +     priv->valids = valids_table[index];
>>>>> +
>>>>> +     ret = stm32_setup_iio_triggers(priv);
>>>>> +     if (ret)
>>>>> +             return ret;
>>>>> +
>>>>> +     platform_set_drvdata(pdev, priv);
>>>>> +
>>>>> +     return 0;
>>>>> +}
>>>>> +
>>>>> +static const struct of_device_id stm32_trig_of_match[] = {
>>>>> +     { .compatible = "st,stm32-timer-trigger", },
>>>>> +     { /* end node */ },
>>>>> +};
>>>>> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
>>>>> +
>>>>> +static struct platform_driver stm32_timer_trigger_driver = {
>>>>> +     .probe = stm32_timer_trigger_probe,
>>>>> +     .driver = {
>>>>> +             .name = "stm32-timer-trigger",
>>>>> +             .of_match_table = stm32_trig_of_match,
>>>>> +     },
>>>>> +};
>>>>> +module_platform_driver(stm32_timer_trigger_driver);
>>>>> +
>>>>> +MODULE_ALIAS("platform: stm32-timer-trigger");
>>>>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger
>driver");
>>>>> +MODULE_LICENSE("GPL v2");
>>>>> diff --git a/drivers/iio/trigger/Kconfig
>b/drivers/iio/trigger/Kconfig
>>>>> index 809b2e7..f2af4fe 100644
>>>>> --- a/drivers/iio/trigger/Kconfig
>>>>> +++ b/drivers/iio/trigger/Kconfig
>>>>> @@ -46,5 +46,4 @@ config IIO_SYSFS_TRIGGER
>>>>>
>>>>>         To compile this driver as a module, choose M here: the
>>>>>         module will be called iio-trig-sysfs.
>>>>> -
>>>> Clean this up.
>>>
>>> ok
>>>
>>>>>  endmenu
>>>>> diff --git a/include/linux/iio/timer/stm32-timer-trigger.h
>b/include/linux/iio/timer/stm32-timer-trigger.h
>>>>> new file mode 100644
>>>>> index 0000000..55535ae
>>>>> --- /dev/null
>>>>> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
>>>>> @@ -0,0 +1,62 @@
>>>>> +/*
>>>>> + * Copyright (C) STMicroelectronics 2016
>>>>> + *
>>>>> + * Author: Benjamin Gaignard <[e-mail]>
>>>>> + *
>>>>> + * License terms:  GNU General Public License (GPL), version 2
>>>>> + */
>>>>> +
>>>>> +#ifndef _STM32_TIMER_TRIGGER_H_
>>>>> +#define _STM32_TIMER_TRIGGER_H_
>>>>> +
>>>>> +#define TIM1_TRGO    "tim1_trgo"
>>>>> +#define TIM1_CH1     "tim1_ch1"
>>>>> +#define TIM1_CH2     "tim1_ch2"
>>>>> +#define TIM1_CH3     "tim1_ch3"
>>>>> +#define TIM1_CH4     "tim1_ch4"
>>>>> +
>>>>> +#define TIM2_TRGO    "tim2_trgo"
>>>>> +#define TIM2_CH1     "tim2_ch1"
>>>>> +#define TIM2_CH2     "tim2_ch2"
>>>>> +#define TIM2_CH3     "tim2_ch3"
>>>>> +#define TIM2_CH4     "tim2_ch4"
>>>>> +
>>>>> +#define TIM3_TRGO    "tim3_trgo"
>>>>> +#define TIM3_CH1     "tim3_ch1"
>>>>> +#define TIM3_CH2     "tim3_ch2"
>>>>> +#define TIM3_CH3     "tim3_ch3"
>>>>> +#define TIM3_CH4     "tim3_ch4"
>>>>> +
>>>>> +#define TIM4_TRGO    "tim4_trgo"
>>>>> +#define TIM4_CH1     "tim4_ch1"
>>>>> +#define TIM4_CH2     "tim4_ch2"
>>>>> +#define TIM4_CH3     "tim4_ch3"
>>>>> +#define TIM4_CH4     "tim4_ch4"
>>>>> +
>>>>> +#define TIM5_TRGO    "tim5_trgo"
>>>>> +#define TIM5_CH1     "tim5_ch1"
>>>>> +#define TIM5_CH2     "tim5_ch2"
>>>>> +#define TIM5_CH3     "tim5_ch3"
>>>>> +#define TIM5_CH4     "tim5_ch4"
>>>>> +
>>>>> +#define TIM6_TRGO    "tim6_trgo"
>>>>> +
>>>>> +#define TIM7_TRGO    "tim7_trgo"
>>>>> +
>>>>> +#define TIM8_TRGO    "tim8_trgo"
>>>>> +#define TIM8_CH1     "tim8_ch1"
>>>>> +#define TIM8_CH2     "tim8_ch2"
>>>>> +#define TIM8_CH3     "tim8_ch3"
>>>>> +#define TIM8_CH4     "tim8_ch4"
>>>>> +
>>>>> +#define TIM9_TRGO    "tim9_trgo"
>>>>> +#define TIM9_CH1     "tim9_ch1"
>>>>> +#define TIM9_CH2     "tim9_ch2"
>>>>> +
>>>>> +#define TIM12_TRGO   "tim12_trgo"
>>>>> +#define TIM12_CH1    "tim12_ch1"
>>>>> +#define TIM12_CH2    "tim12_ch2"
>>>>> +
>>>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
>>>>> +
>>>>> +#endif
>>>>>
>>>>
>>>
>>>
>>>
>>

Jonathan Cameron Jan. 3, 2017, 5:24 p.m. UTC | #7

On 3 January 2017 12:59:20 GMT+00:00, Benjamin Gaignard <[e-mail]> wrote:
>2017-01-03 10:23 GMT+01:00 Benjamin Gaignard
><[e-mail]>:
>> 2017-01-02 19:22 GMT+01:00 Jonathan Cameron <[e-mail]>:
>>> On 02/01/17 08:46, Benjamin Gaignard wrote:
>>>> 2016-12-30 22:12 GMT+01:00 Jonathan Cameron <[e-mail]>:
>>>>> On 09/12/16 14:15, Benjamin Gaignard wrote:
>>>>>> Timers IPs can be used to generate triggers for other IPs like
>>>>>> DAC, ADC or other timers.
>>>>>> Each trigger may result of timer internals signals like counter
>enable,
>>>>>> reset or edge, this configuration could be done through
>"master_mode"
>>>>>> device attribute.
>>>>>>
>>>>>> A timer device could be triggered by other timers, we use the
>trigger
>>>>>> name and is_stm32_iio_timer_trigger() function to distinguish
>them
>>>>>> and configure IP input switch.
>>>>>>
>>>>>> Timer may also decide on which event (edge, level) they could
>>>>>> be activated by a trigger, this configuration is done by writing
>in
>>>>>> "slave_mode" device attribute.
>>>>>>
>>>>>> Since triggers could also be used by DAC or ADC their names are
>defined
>>>>>> in include/ nux/iio/timer/stm32-timer-trigger.h so those IPs will
>be able
>>>>>> to configure themselves in valid_trigger function
>>>>>>
>>>>>> Trigger have a "sampling_frequency" attribute which allow to
>configure
>>>>>> timer sampling frequency without using PWM interface
>>>>>>
>>>>>> version 5:
>>>>>> - simplify tables of triggers
>>>>>> - only create an IIO device when needed
>>>>>>
>>>>>> version 4:
>>>>>> - get triggers configuration from "reg" in DT
>>>>>> - add tables of triggers
>>>>>> - sampling frequency is enable/disable when writing in trigger
>>>>>>   sampling_frequency attribute
>>>>>> - no more use of interruptions
>>>>>>
>>>>>> version 3:
>>>>>> - change compatible to "st,stm32-timer-trigger"
>>>>>> - fix attributes access right
>>>>>> - use string instead of int for master_mode and slave_mode
>>>>>> - document device attributes in sysfs-bus-iio-timer-stm32
>>>>>>
>>>>>> version 2:
>>>>>> - keep only one compatible
>>>>>> - use st,input-triggers-names and st,output-triggers-names
>>>>>>   to know which triggers are accepted and/or create by the device
>>>>> Firstly, sorry it has taken me so long to get back to this.
>>>>>
>>>>> I'm still not keen on this use of iio_device elements just to act
>as
>>>>> glue between triggers.  I think we need to work out a more light
>weight
>>>>> way to do this.  As you are only using them for validation and to
>provide
>>>>> somewhere to hang the control attibutes off, there is nothing
>stopping us
>>>>> moving that over to the iio_trigger instead which would avoid the
>messy
>>>>> duality going on here.
>>>>
>>>> I have add an iio_device because each hardware can generate
>multiple
>>>> triggers (up to 5: trgo, ch 1...4) and slave_mode attribute will
>impact all the
>>>> triggers of a device. For me it was making sense to centralize that
>in an
>>>> iio_device rather than having an attribute "shared" (from hardware
>>>> point of view)
>>>> on multiple triggers.
>>>> Since master_mode attribute is only used by trgo and not impact
>ch1...4
>>>> triggers I will move it to trigger instead of the iio_device.
>>>>
>>>> I also wanted to be able to connect triggers on a iio_device as I
>>>> could do for an
>>>> ADC with a command like 'echo "tim1_trgo" >
>iio_deviceX/trigger/current_trigger'
>>> This is interesting, but with a bit of refactoring I would think it
>would
>>> be possible to share some of that code thus allowing non IIO devices
>to
>>> bind to triggers.  Ultimately I want to be able to bind a trigger to
>>> a trigger - I appreciate here the topology is more limited than that
>>> so some complexity comes in.
>>>
>>> My gut feeling is that representing that topology explicitly is hard
>>> to do in a remotely general way, but lets try it and see.
>>> We run into this sort of interdependency issue between different
>bits of
>>> the hardware all the time.  Setting a value somewhere effects the
>configuration
>>> elsewhere - often the best plan is to just let that happen and leave
>it up to
>>> userspace to check for changes if it cares.
>>
>> okay
>>
>>>> If I change that to parent_trigger attribute it change this
>behavior
>>>> and I will have to
>>>> duplicated what is done in iio_trigger_write_current() to find and
>>>> validate triggers.
>>> I get the reasoning, but we still end up with something represented
>>> by an IIO device that isn't providing any channels at all. It's
>simply
>>> using some of the infrastructure.  To my mind it is 'something else'
>>> and should be represented as such.  I have no problem at all with
>>> you registering additional elements in /sysfs/bus/iio/ to represent
>>> these shared elements - we already have drivers that do that to
>>> provide some centralized infrastructure (e.g. the sysfs-trigger)
>>
>> My hardware block are timers maybe I can add a channel type
>"IIO_TIMER"
>> and declare a channel with info_mask_separate =
>BIT(IIO_CHAN_INFO_SAMP_FREQ)
>> so I will be able to write/read sampling frequency on IIO device.
>>
>
>If it isn't possible to implement IIO_TIMER I will simply drop device
>part of
>my driver until we find a solution because I would like to upstream at
>least what is
>need to ADC/DAC.

Agreed. Let's move forward with the easy stuff.
I might get a chance to look at trigger trees later
this week depending on how some tedious time in a pharma clean room and on planes goes.

I think we can mock most of this up with software triggers and the dummy driver.

Perhaps a sysfs trigger driving a timer trigger will get us moving in the right direction API wise.
Might let us figure out something generic without needing hardware.

A few other bits of hardware can do similar to yours but I don't think I have any in my pile of boards.

J
>
>>> I'm worried about the scope spread we get for an IIO device
>otherwise.
>>> They serve a well defined purpose at the moment, and that isn't what
>>> is happening here.
>>>
>>> So my gut feeling is we are better deliberately not representing the
>>> inter dependence and claiming all triggers we are creating are
>>> independent.  That way we can have a nice generic infrastructure
>>> that will work in all cases (be it pushing the sanity checking to
>>> userspace).
>>>
>>> So each trigger has direct access to what controls it.  Changing
>anything
>>> can effect other triggers in weird ways.
>>>
>>> I'm finding it hard to see anything else generalizing sufficiently
>>> as we'll always get cases where we can't represent the topology
>without
>>> diving into the complexity of something like the media controller
>>> framework.
>>>
>>> Jonathan
>>>>
>>>>> I might still be missing something though!
>>>>>
>>>>> You would only I think need 3 attributes
>>>>>
>>>>> parrent_trigger
>>>>> and something like your master_mode and slave_mode attributes.
>>>>>
>>>>> The parrent_trigger would need some validation etc, but if we keep
>it
>>>>> within this driver initially that won't be hard to do. Checking
>the device
>>>>> parent matches will do most of it.
>>>>>
>>>>> Jonathan
>>>>>>
>>>>>> Signed-off-by: Benjamin Gaignard <[e-mail]>
>>>>>> ---
>>>>>>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  55 +++
>>>>>>  drivers/iio/Kconfig                                |   2 +-
>>>>>>  drivers/iio/Makefile                               |   1 +
>>>>>>  drivers/iio/timer/Kconfig                          |  13 +
>>>>>>  drivers/iio/timer/Makefile                         |   1 +
>>>>>>  drivers/iio/timer/stm32-timer-trigger.c            | 466
>+++++++++++++++++++++
>>>>>>  drivers/iio/trigger/Kconfig                        |   1 -
>>>>>>  include/linux/iio/timer/stm32-timer-trigger.h      |  62 +++
>>>>>>  8 files changed, 599 insertions(+), 2 deletions(-)
>>>>>>  create mode 100644
>Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>>>  create mode 100644 drivers/iio/timer/Kconfig
>>>>>>  create mode 100644 drivers/iio/timer/Makefile
>>>>>>  create mode 100644 drivers/iio/timer/stm32-timer-trigger.c
>>>>>>  create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h
>>>>>>
>>>>>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>>> new file mode 100644
>>>>>> index 0000000..26583dd
>>>>>> --- /dev/null
>>>>>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>>>>> @@ -0,0 +1,55 @@
>>>>>> +What:               
>/sys/bus/iio/devices/iio:deviceX/master_mode_available
>>>>>> +KernelVersion:       4.10
>>>>>> +Contact:     [e-mail]
>>>>>> +Description:
>>>>>> +             Reading returns the list possible master modes
>which are:
>>>>>> +             - "reset"     : The UG bit from the TIMx_EGR
>register is used as trigger output (TRGO).
>>>>>> +             - "enable"    : The Counter Enable signal CNT_EN is
>used as trigger output.
>>>>>> +             - "update"    : The update event is selected as
>trigger output.
>>>>>> +                             For instance a master timer can
>then be used as a prescaler for a slave timer.
>>>>>> +             - "compare_pulse" : The trigger output send a
>positive pulse when the CC1IF flag is to be set.
>>>>>> +             - "OC1REF"    : OC1REF signal is used as trigger
>output.
>>>>>> +             - "OC2REF"    : OC2REF signal is used as trigger
>output.
>>>>>> +             - "OC3REF"    : OC3REF signal is used as trigger
>output.
>>>>>> +             - "OC4REF"    : OC4REF signal is used as trigger
>output.
>>>>>> +
>>>>>> +What:               
>/sys/bus/iio/devices/iio:deviceX/master_mode
>>>>>> +KernelVersion:       4.10
>>>>>> +Contact:     [e-mail]
>>>>>> +Description:
>>>>>> +             Reading returns the current master modes.
>>>>>> +             Writing set the master mode
>>>>>> +
>>>>>> +What:               
>/sys/bus/iio/devices/iio:deviceX/slave_mode_available
>>>>>> +KernelVersion:       4.10
>>>>>> +Contact:     [e-mail]
>>>>>> +Description:
>>>>>> +             Reading returns the list possible slave modes which
>are:
>>>>>> +             - "disabled"  : The prescaler is clocked directly
>by the internal clock.
>>>>>> +             - "encoder_1" : Counter counts up/down on TI2FP1
>edge depending on TI1FP2 level.
>>>>>> +             - "encoder_2" : Counter counts up/down on TI1FP2
>edge depending on TI2FP1 level.
>>>>>> +             - "encoder_3" : Counter counts up/down on both
>TI1FP1 and TI2FP2 edges depending
>>>>>> +                             on the level of the other input.
>>>>>> +             - "reset"     : Rising edge of the selected trigger
>input reinitializes the counter
>>>>>> +                             and generates an update of the
>registers.
>>>>>> +             - "gated"     : The counter clock is enabled when
>the trigger input is high.
>>>>>> +                             The counter stops (but is not
>reset) as soon as the trigger becomes low.
>>>>>> +                             Both start and stop of the counter
>are controlled.
>>>>>> +             - "trigger"   : The counter starts at a rising edge
>of the trigger TRGI (but it is not
>>>>>> +                             reset). Only the start of the
>counter is controlled.
>>>>>> +             - "external_clock": Rising edges of the selected
>trigger (TRGI) clock the counter.
>>>>>> +
>>>>>> +What:                /sys/bus/iio/devices/iio:deviceX/slave_mode
>>>>>> +KernelVersion:       4.10
>>>>>> +Contact:     [e-mail]
>>>>>> +Description:
>>>>>> +             Reading returns the current slave mode.
>>>>>> +             Writing set the slave mode
>>>>>> +
>>>>>> +What:               
>/sys/bus/iio/devices/triggerX/sampling_frequency
>>>>>> +KernelVersion:       4.10
>>>>>> +Contact:     [e-mail]
>>>>>> +Description:
>>>>>> +             Reading returns the current sampling frequency.
>>>>>> +             Writing an value different of 0 set and start
>sampling.
>>>>>> +             Writing 0 stop sampling.
>>>>>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>>>>>> index 6743b18..2de2a80 100644
>>>>>> --- a/drivers/iio/Kconfig
>>>>>> +++ b/drivers/iio/Kconfig
>>>>>> @@ -90,5 +90,5 @@ source "drivers/iio/potentiometer/Kconfig"
>>>>>>  source "drivers/iio/pressure/Kconfig"
>>>>>>  source "drivers/iio/proximity/Kconfig"
>>>>>>  source "drivers/iio/temperature/Kconfig"
>>>>>> -
>>>>>> +source "drivers/iio/timer/Kconfig"
>>>>>>  endif # IIO
>>>>>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>>>>>> index 87e4c43..b797c08 100644
>>>>>> --- a/drivers/iio/Makefile
>>>>>> +++ b/drivers/iio/Makefile
>>>>>> @@ -32,4 +32,5 @@ obj-y += potentiometer/
>>>>>>  obj-y += pressure/
>>>>>>  obj-y += proximity/
>>>>>>  obj-y += temperature/
>>>>>> +obj-y += timer/
>>>>>>  obj-y += trigger/
>>>>>> diff --git a/drivers/iio/timer/Kconfig
>b/drivers/iio/timer/Kconfig
>>>>>> new file mode 100644
>>>>>> index 0000000..e3c21f2
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/iio/timer/Kconfig
>>>>>> @@ -0,0 +1,13 @@
>>>>>> +#
>>>>>> +# Timers drivers
>>>>>> +
>>>>>> +menu "Timers"
>>>>>> +
>>>>>> +config IIO_STM32_TIMER_TRIGGER
>>>>>> +     tristate "STM32 Timer Trigger"
>>>>>> +     depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) ||
>COMPILE_TEST
>>>>>> +     select IIO_TRIGGERED_EVENT
>>>>>> +     help
>>>>>> +       Select this option to enable STM32 Timer Trigger
>>>>>> +
>>>>>> +endmenu
>>>>>> diff --git a/drivers/iio/timer/Makefile
>b/drivers/iio/timer/Makefile
>>>>>> new file mode 100644
>>>>>> index 0000000..4ad95ec9
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/iio/timer/Makefile
>>>>>> @@ -0,0 +1 @@
>>>>>> +obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
>>>>>> diff --git a/drivers/iio/timer/stm32-timer-trigger.c
>b/drivers/iio/timer/stm32-timer-trigger.c
>>>>>> new file mode 100644
>>>>>> index 0000000..8d16e8f
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/iio/timer/stm32-timer-trigger.c
>>>>>> @@ -0,0 +1,466 @@
>>>>>> +/*
>>>>>> + * Copyright (C) STMicroelectronics 2016
>>>>>> + *
>>>>>> + * Author: Benjamin Gaignard <[e-mail]>
>>>>>> + *
>>>>>> + * License terms:  GNU General Public License (GPL), version 2
>>>>>> + */
>>>>>> +
>>>>>> +#include <linux/iio/iio.h>
>>>>>> +#include <linux/iio/sysfs.h>
>>>>>> +#include <linux/iio/timer/stm32-timer-trigger.h>
>>>>>> +#include <linux/iio/trigger.h>
>>>>>> +#include <linux/iio/triggered_event.h>
>>>>>> +#include <linux/interrupt.h>
>>>>>> +#include <linux/mfd/stm32-timers.h>
>>>>>> +#include <linux/module.h>
>>>>>> +#include <linux/platform_device.h>
>>>>>> +
>>>>>> +#define MAX_TRIGGERS 6
>>>>>> +#define MAX_VALIDS 5
>>>>>> +
>>>>>> +/* List the triggers created by each timer */
>>>>>> +static const void *triggers_table[][MAX_TRIGGERS] = {
>>>>>> +     { TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
>>>>>> +     { TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
>>>>>> +     { TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
>>>>>> +     { TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
>>>>>> +     { TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
>>>>>> +     { TIM6_TRGO,},
>>>>>> +     { TIM7_TRGO,},
>>>>>> +     { TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
>>>>>> +     { TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
>>>>>> +     { TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
>>>>>> +};
>>>>>> +
>>>>>> +/* List the triggers accepted by each timer */
>>>>>> +static const void *valids_table[][MAX_VALIDS] = {
>>>>>> +     { TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
>>>>>> +     { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
>>>>>> +     { TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
>>>>>> +     { TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
>>>>>> +     { TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
>>>>>> +     { }, /* timer 6 */
>>>>>> +     { }, /* timer 7 */
>>>>>> +     { TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
>>>>>> +     { TIM2_TRGO, TIM3_TRGO,},
>>>>>> +     { TIM4_TRGO, TIM5_TRGO,},
>>>>>> +};
>>>>>> +
>>>>>> +struct stm32_timer_trigger {
>>>>>> +     struct device *dev;
>>>>>> +     struct regmap *regmap;
>>>>>> +     struct clk *clk;
>>>>>> +     u32 max_arr;
>>>>>> +     const void *triggers;
>>>>>> +     const void *valids;
>>>>>> +};
>>>>>> +
>>>>>> +static int stm32_timer_start(struct stm32_timer_trigger *priv,
>>>>>> +                          unsigned int frequency)
>>>>>> +{
>>>>>> +     unsigned long long prd, div;
>>>>>> +     int prescaler = 0;
>>>>>> +     u32 ccer, cr1;
>>>>>> +
>>>>>> +     /* Period and prescaler values depends of clock rate */
>>>>>> +     div = (unsigned long long)clk_get_rate(priv->clk);
>>>>>> +
>>>>>> +     do_div(div, frequency);
>>>>>> +
>>>>>> +     prd = div;
>>>>>> +
>>>>>> +     /*
>>>>>> +      * Increase prescaler value until we get a result that fit
>>>>>> +      * with auto reload register maximum value.
>>>>>> +      */
>>>>>> +     while (div > priv->max_arr) {
>>>>>> +             prescaler++;
>>>>>> +             div = prd;
>>>>>> +             do_div(div, (prescaler + 1));
>>>>>> +     }
>>>>>> +     prd = div;
>>>>>> +
>>>>>> +     if (prescaler > MAX_TIM_PSC) {
>>>>>> +             dev_err(priv->dev, "prescaler exceeds the maximum
>value\n");
>>>>>> +             return -EINVAL;
>>>>>> +     }
>>>>>> +
>>>>>> +     /* Check if nobody else use the timer */
>>>>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>>>>> +     if (ccer & TIM_CCER_CCXE)
>>>>>> +             return -EBUSY;
>>>>>> +
>>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>>> +     if (!(cr1 & TIM_CR1_CEN))
>>>>>> +             clk_enable(priv->clk);
>>>>>> +
>>>>>> +     regmap_write(priv->regmap, TIM_PSC, prescaler);
>>>>>> +     regmap_write(priv->regmap, TIM_ARR, prd - 1);
>>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE,
>TIM_CR1_ARPE);
>>>>>> +
>>>>>> +     /* Force master mode to update mode */
>>>>>> +     regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS,
>0x20);
>>>>>> +
>>>>>> +     /* Make sure that registers are updated */
>>>>>> +     regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG,
>TIM_EGR_UG);
>>>>>> +
>>>>>> +     /* Enable controller */
>>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN,
>TIM_CR1_CEN);
>>>>>> +
>>>>>> +     return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static void stm32_timer_stop(struct stm32_timer_trigger *priv)
>>>>>> +{
>>>>>> +     u32 ccer, cr1;
>>>>>> +
>>>>>> +     regmap_read(priv->regmap, TIM_CCER, &ccer);
>>>>>> +     if (ccer & TIM_CCER_CCXE)
>>>>>> +             return;
>>>>>> +
>>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>>> +     if (cr1 & TIM_CR1_CEN)
>>>>>> +             clk_disable(priv->clk);
>>>>>> +
>>>>>> +     /* Stop timer */
>>>>>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
>>>>>> +     regmap_write(priv->regmap, TIM_PSC, 0);
>>>>>> +     regmap_write(priv->regmap, TIM_ARR, 0);
>>>>>> +}
>>>>>> +
>>>>>> +static ssize_t stm32_tt_store_frequency(struct device *dev,
>>>>>> +                                     struct device_attribute
>*attr,
>>>>>> +                                     const char *buf, size_t
>len)
>>>>>> +{
>>>>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>>>>> +     struct stm32_timer_trigger *priv =
>iio_trigger_get_drvdata(trig);
>>>>>> +     unsigned int freq;
>>>>>> +     int ret;
>>>>>> +
>>>>>> +     ret = kstrtouint(buf, 10, &freq);
>>>>>> +     if (ret)
>>>>>> +             return ret;
>>>>>> +
>>>>>> +     if (freq == 0) {
>>>>>> +             stm32_timer_stop(priv);
>>>>>> +     } else {
>>>>>> +             ret = stm32_timer_start(priv, freq);
>>>>>> +             if (ret)
>>>>>> +                     return ret;
>>>>>> +     }
>>>>>> +
>>>>>> +     return len;
>>>>>> +}
>>>>>> +
>>>>>> +static ssize_t stm32_tt_read_frequency(struct device *dev,
>>>>>> +                                    struct device_attribute
>*attr, char *buf)
>>>>>> +{
>>>>>> +     struct iio_trigger *trig = to_iio_trigger(dev);
>>>>>> +     struct stm32_timer_trigger *priv =
>iio_trigger_get_drvdata(trig);
>>>>>> +     u32 psc, arr, cr1;
>>>>>> +     unsigned long long freq = 0;
>>>>>> +
>>>>>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>>>>>> +     regmap_read(priv->regmap, TIM_PSC, &psc);
>>>>>> +     regmap_read(priv->regmap, TIM_ARR, &arr);
>>>>>> +
>>>>>> +     if (psc && arr && (cr1 & TIM_CR1_CEN)) {
>>>>>> +             freq = (unsigned long long)clk_get_rate(priv->clk);
>>>>>> +             do_div(freq, psc);
>>>>>> +             do_div(freq, arr);
>>>>>> +     }
>>>>>> +
>>>>>> +     return sprintf(buf, "%d\n", (unsigned int)freq);
>>>>>> +}
>>>>>> +
>>>>>> +static IIO_DEV_ATTR_SAMP_FREQ(0660,
>>>>>> +                           stm32_tt_read_frequency,
>>>>>> +                           stm32_tt_store_frequency);
>>>>>> +
>>>>>> +static struct attribute *stm32_trigger_attrs[] = {
>>>>>> +     &iio_dev_attr_sampling_frequency.dev_attr.attr,
>>>>>> +     NULL,
>>>>>> +};
>>>>>> +
>>>>>> +static const struct attribute_group stm32_trigger_attr_group = {
>>>>>> +     .attrs = stm32_trigger_attrs,
>>>>>> +};
>>>>>> +
>>>>>> +static const struct attribute_group *stm32_trigger_attr_groups[]
>= {
>>>>>> +     &stm32_trigger_attr_group,
>>>>>> +     NULL,
>>>>>> +};
>>>>>> +
>>>>>> +static char *master_mode_table[] = {
>>>>>> +     "reset",
>>>>>> +     "enable",
>>>>>> +     "update",
>>>>>> +     "compare_pulse",
>>>>>> +     "OC1REF",
>>>>>> +     "OC2REF",
>>>>>> +     "OC3REF",
>>>>>> +     "OC4REF"
>>>>>> +};
>>>>>> +
>>>>>> +static ssize_t stm32_tt_show_master_mode(struct device *dev,
>>>>>> +                                      struct device_attribute
>*attr,
>>>>>> +                                      char *buf)
>>>>>> +{
>>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>>> +     u32 cr2;
>>>>>> +
>>>>>> +     regmap_read(priv->regmap, TIM_CR2, &cr2);
>>>>>> +     cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
>>>>>> +
>>>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n",
>master_mode_table[cr2]);
>>>>>> +}
>>>>>> +
>>>>>> +static ssize_t stm32_tt_store_master_mode(struct device *dev,
>>>>>> +                                       struct device_attribute
>*attr,
>>>>>> +                                       const char *buf, size_t
>len)
>>>>>> +{
>>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>>> +     int i;
>>>>>> +
>>>>>> +     for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
>>>>>> +             if (!strncmp(master_mode_table[i], buf,
>>>>>> +                          strlen(master_mode_table[i]))) {
>>>>>> +                     regmap_update_bits(priv->regmap, TIM_CR2,
>>>>>> +                                        TIM_CR2_MMS, i <<
>TIM_CR2_MMS_SHIFT);
>>>>>> +                     return len;
>>>>>> +             }
>>>>>> +     }
>>>>>> +
>>>>>> +     return -EINVAL;
>>>>>> +}
>>>>>> +
>>>>>> +static IIO_CONST_ATTR(master_mode_available,
>>>>>> +     "reset enable update compare_pulse OC1REF OC2REF OC3REF
>OC4REF");
>>>>>> +
>>>>>> +static IIO_DEVICE_ATTR(master_mode, 0660,
>>>>>> +                    stm32_tt_show_master_mode,
>>>>>> +                    stm32_tt_store_master_mode,
>>>>>> +                    0);
>>>>>> +
>>>>>> +static char *slave_mode_table[] = {
>>>>>> +     "disabled",
>>>>>> +     "encoder_1",
>>>>>> +     "encoder_2",
>>>>>> +     "encoder_3",
>>>>>> +     "reset",
>>>>>> +     "gated",
>>>>>> +     "trigger",
>>>>>> +     "external_clock",
>>>>>> +};
>>>>>> +
>>>>>> +static ssize_t stm32_tt_show_slave_mode(struct device *dev,
>>>>>> +                                     struct device_attribute
>*attr,
>>>>>> +                                     char *buf)
>>>>>> +{
>>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>>> +     u32 smcr;
>>>>>> +
>>>>>> +     regmap_read(priv->regmap, TIM_SMCR, &smcr);
>>>>>> +     smcr &= TIM_SMCR_SMS;
>>>>>> +
>>>>>> +     return snprintf(buf, PAGE_SIZE, "%s\n",
>slave_mode_table[smcr]);
>>>>>> +}
>>>>>> +
>>>>>> +static ssize_t stm32_tt_store_slave_mode(struct device *dev,
>>>>>> +                                      struct device_attribute
>*attr,
>>>>>> +                                      const char *buf, size_t
>len)
>>>>>> +{
>>>>>> +     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>>> +     int i;
>>>>>> +
>>>>>> +     for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
>>>>>> +             if (!strncmp(slave_mode_table[i], buf,
>>>>>> +                          strlen(slave_mode_table[i]))) {
>>>>>> +                     regmap_update_bits(priv->regmap,
>>>>>> +                                        TIM_SMCR, TIM_SMCR_SMS,
>i);
>>>>>> +                     return len;
>>>>>> +             }
>>>>>> +     }
>>>>>> +
>>>>>> +     return -EINVAL;
>>>>>> +}
>>>>>> +
>>>>>> +static IIO_CONST_ATTR(slave_mode_available,
>>>>>> +"disabled encoder_1 encoder_2 encoder_3 reset gated trigger
>external_clock");
>>>>>> +
>>>>>> +static IIO_DEVICE_ATTR(slave_mode, 0660,
>>>>>> +                    stm32_tt_show_slave_mode,
>>>>>> +                    stm32_tt_store_slave_mode,
>>>>>> +                    0);
>>>>>> +
>>>>>> +static struct attribute *stm32_timer_attrs[] = {
>>>>>> +     &iio_dev_attr_master_mode.dev_attr.attr,
>>>>>> +     &iio_const_attr_master_mode_available.dev_attr.attr,
>>>>>> +     &iio_dev_attr_slave_mode.dev_attr.attr,
>>>>>> +     &iio_const_attr_slave_mode_available.dev_attr.attr,
>>>>>> +     NULL,
>>>>>> +};
>>>>>> +
>>>>>> +static const struct attribute_group stm32_timer_attr_group = {
>>>>>> +     .attrs = stm32_timer_attrs,
>>>>>> +};
>>>>>> +
>>>>>> +static const struct iio_trigger_ops timer_trigger_ops = {
>>>>>> +     .owner = THIS_MODULE,
>>>>>> +};
>>>>>> +
>>>>>> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger
>*priv)
>>>>>> +{
>>>>>> +     int ret;
>>>>>> +     const char * const *cur = priv->triggers;
>>>>>> +
>>>>>> +     while (cur && *cur) {
>>>>>> +             struct iio_trigger *trig;
>>>>>> +
>>>>>> +             trig = devm_iio_trigger_alloc(priv->dev, "%s",
>*cur);
>>>>>> +             if  (!trig)
>>>>>> +                     return -ENOMEM;
>>>>>> +
>>>>>> +             trig->dev.parent = priv->dev->parent;
>>>>>> +             trig->ops = &timer_trigger_ops;
>>>>>> +             trig->dev.groups = stm32_trigger_attr_groups;
>>>>>> +             iio_trigger_set_drvdata(trig, priv);
>>>>>> +
>>>>>> +             ret = devm_iio_trigger_register(priv->dev, trig);
>>>>>> +             if (ret)
>>>>>> +                     return ret;
>>>>>> +             cur++;
>>>>>> +     }
>>>>>> +
>>>>>> +     return 0;
>>>>>> +}
>>>>>> +
>>>>>> +/**
>>>>>> + * is_stm32_timer_trigger
>>>>>> + * @trig: trigger to be checked
>>>>>> + *
>>>>>> + * return true if the trigger is a valid stm32 iio timer trigger
>>>>>> + * either return false
>>>>>> + */
>>>>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig)
>>>>>> +{
>>>>>> +     return (trig->ops == &timer_trigger_ops);
>>>>>> +}
>>>>>> +EXPORT_SYMBOL(is_stm32_timer_trigger);
>>>>>> +
>>>>>> +static int stm32_validate_trigger(struct iio_dev *indio_dev,
>>>>>> +                               struct iio_trigger *trig)
>>>>>> +{
>>>>>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>>>>>> +     const char * const *cur = priv->valids;
>>>>>> +     unsigned int i = 0;
>>>>>> +
>>>>>> +     if (!is_stm32_timer_trigger(trig))
>>>>>> +             return -EINVAL;
>>>>>> +
>>>>>> +     while (cur && *cur) {
>>>>>> +             if (!strncmp(trig->name, *cur, strlen(trig->name)))
>{
>>>>>> +                     regmap_update_bits(priv->regmap,
>>>>>> +                                        TIM_SMCR, TIM_SMCR_TS,
>>>>>> +                                        i << TIM_SMCR_TS_SHIFT);
>>>>>> +                     return 0;
>>>>>> +             }
>>>>>> +             cur++;
>>>>>> +             i++;
>>>>>> +     }
>>>>>> +
>>>>>> +     return -EINVAL;
>>>>>> +}
>>>>>> +
>>>>>> +static const struct iio_info stm32_trigger_info = {
>>>>>> +     .driver_module = THIS_MODULE,
>>>>>> +     .validate_trigger = stm32_validate_trigger,
>>>>>> +     .attrs = &stm32_timer_attr_group,
>>>>>> +};
>>>>>> +
>>>>>> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct
>device *dev)
>>>>>> +{
>>>>>> +     struct iio_dev *indio_dev;
>>>>>> +     int ret;
>>>>>> +
>>>>>> +     indio_dev = devm_iio_device_alloc(dev,
>>>>>> +                                       sizeof(struct
>stm32_timer_trigger));
>>>>>> +     if (!indio_dev)
>>>>>> +             return NULL;
>>>>>> +
>>>>>> +     indio_dev->name = dev_name(dev);
>>>>>> +     indio_dev->dev.parent = dev;
>>>>>> +     indio_dev->info = &stm32_trigger_info;
>>>>>> +     indio_dev->modes = INDIO_EVENT_TRIGGERED;
>>>>>> +     indio_dev->num_channels = 0;
>>>>>> +     indio_dev->dev.of_node = dev->of_node;
>>>>>> +
>>>>>> +     ret = devm_iio_device_register(dev, indio_dev);
>>>>>> +     if (ret)
>>>>>> +             return NULL;
>>>>>> +
>>>>>> +     return iio_priv(indio_dev);
>>>>>> +}
>>>>>> +
>>>>>> +static int stm32_timer_trigger_probe(struct platform_device
>*pdev)
>>>>>> +{
>>>>>> +     struct device *dev = &pdev->dev;
>>>>>> +     struct stm32_timer_trigger *priv;
>>>>>> +     struct stm32_timers *ddata =
>dev_get_drvdata(pdev->dev.parent);
>>>>>> +     unsigned int index;
>>>>>> +     int ret;
>>>>>> +
>>>>>> +     if (of_property_read_u32(dev->of_node, "reg", &index))
>>>>>> +             return -EINVAL;
>>>>>> +
>>>>>> +     if (index >= ARRAY_SIZE(triggers_table))
>>>>>> +             return -EINVAL;
>>>>>> +
>>>>>> +     /* Create an IIO device only if we have triggers to be
>validated */
>>>>>> +     if (*valids_table[index])
>>>>>> +             priv = stm32_setup_iio_device(dev);
>>>>>
>>>>> I still don't like this. Really feels like we shouldn't be
>creating an
>>>>> iio device with all the bagage that carries just to allow us to do
>the
>>>>> trigger trees.  We ought to have a much more light weight solution
>for this
>>>>> functionality - we aren't typically even using the interrupt tree
>stuff
>>>>> that the triggers for devices are all really about.
>>>>>
>>>>> A simpler approach of allowing each trigger the option of a parent
>seems like
>>>>> it would be cleaner.  Could be done entirely within this driver in
>the first
>>>>> instance.  Basically it would just look like your master and slave
>attributes
>>>>> but have those under triggerX not iio:deviceX.
>>>>>
>>>>> We can work out how to make it more generic later - including
>perhaps the
>>>>> option to trigger from triggers outside this driver, using some
>parallel
>>>>> infrastructure to the device triggering.
>>>>>
>>>>>
>>>>>> +     else
>>>>>> +             priv = devm_kzalloc(dev, sizeof(*priv),
>GFP_KERNEL);
>>>>>> +
>>>>>> +     if (!priv)
>>>>>> +             return -ENOMEM;
>>>>>> +
>>>>>> +     priv->dev = dev;
>>>>>> +     priv->regmap = ddata->regmap;
>>>>>> +     priv->clk = ddata->clk;
>>>>>> +     priv->max_arr = ddata->max_arr;
>>>>>> +     priv->triggers = triggers_table[index];
>>>>>> +     priv->valids = valids_table[index];
>>>>>> +
>>>>>> +     ret = stm32_setup_iio_triggers(priv);
>>>>>> +     if (ret)
>>>>>> +             return ret;
>>>>>> +
>>>>>> +     platform_set_drvdata(pdev, priv);
>>>>>> +
>>>>>> +     return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static const struct of_device_id stm32_trig_of_match[] = {
>>>>>> +     { .compatible = "st,stm32-timer-trigger", },
>>>>>> +     { /* end node */ },
>>>>>> +};
>>>>>> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
>>>>>> +
>>>>>> +static struct platform_driver stm32_timer_trigger_driver = {
>>>>>> +     .probe = stm32_timer_trigger_probe,
>>>>>> +     .driver = {
>>>>>> +             .name = "stm32-timer-trigger",
>>>>>> +             .of_match_table = stm32_trig_of_match,
>>>>>> +     },
>>>>>> +};
>>>>>> +module_platform_driver(stm32_timer_trigger_driver);
>>>>>> +
>>>>>> +MODULE_ALIAS("platform: stm32-timer-trigger");
>>>>>> +MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger
>driver");
>>>>>> +MODULE_LICENSE("GPL v2");
>>>>>> diff --git a/drivers/iio/trigger/Kconfig
>b/drivers/iio/trigger/Kconfig
>>>>>> index 809b2e7..f2af4fe 100644
>>>>>> --- a/drivers/iio/trigger/Kconfig
>>>>>> +++ b/drivers/iio/trigger/Kconfig
>>>>>> @@ -46,5 +46,4 @@ config IIO_SYSFS_TRIGGER
>>>>>>
>>>>>>         To compile this driver as a module, choose M here: the
>>>>>>         module will be called iio-trig-sysfs.
>>>>>> -
>>>>> Clean this up.
>>>>
>>>> ok
>>>>
>>>>>>  endmenu
>>>>>> diff --git a/include/linux/iio/timer/stm32-timer-trigger.h
>b/include/linux/iio/timer/stm32-timer-trigger.h
>>>>>> new file mode 100644
>>>>>> index 0000000..55535ae
>>>>>> --- /dev/null
>>>>>> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
>>>>>> @@ -0,0 +1,62 @@
>>>>>> +/*
>>>>>> + * Copyright (C) STMicroelectronics 2016
>>>>>> + *
>>>>>> + * Author: Benjamin Gaignard <[e-mail]>
>>>>>> + *
>>>>>> + * License terms:  GNU General Public License (GPL), version 2
>>>>>> + */
>>>>>> +
>>>>>> +#ifndef _STM32_TIMER_TRIGGER_H_
>>>>>> +#define _STM32_TIMER_TRIGGER_H_
>>>>>> +
>>>>>> +#define TIM1_TRGO    "tim1_trgo"
>>>>>> +#define TIM1_CH1     "tim1_ch1"
>>>>>> +#define TIM1_CH2     "tim1_ch2"
>>>>>> +#define TIM1_CH3     "tim1_ch3"
>>>>>> +#define TIM1_CH4     "tim1_ch4"
>>>>>> +
>>>>>> +#define TIM2_TRGO    "tim2_trgo"
>>>>>> +#define TIM2_CH1     "tim2_ch1"
>>>>>> +#define TIM2_CH2     "tim2_ch2"
>>>>>> +#define TIM2_CH3     "tim2_ch3"
>>>>>> +#define TIM2_CH4     "tim2_ch4"
>>>>>> +
>>>>>> +#define TIM3_TRGO    "tim3_trgo"
>>>>>> +#define TIM3_CH1     "tim3_ch1"
>>>>>> +#define TIM3_CH2     "tim3_ch2"
>>>>>> +#define TIM3_CH3     "tim3_ch3"
>>>>>> +#define TIM3_CH4     "tim3_ch4"
>>>>>> +
>>>>>> +#define TIM4_TRGO    "tim4_trgo"
>>>>>> +#define TIM4_CH1     "tim4_ch1"
>>>>>> +#define TIM4_CH2     "tim4_ch2"
>>>>>> +#define TIM4_CH3     "tim4_ch3"
>>>>>> +#define TIM4_CH4     "tim4_ch4"
>>>>>> +
>>>>>> +#define TIM5_TRGO    "tim5_trgo"
>>>>>> +#define TIM5_CH1     "tim5_ch1"
>>>>>> +#define TIM5_CH2     "tim5_ch2"
>>>>>> +#define TIM5_CH3     "tim5_ch3"
>>>>>> +#define TIM5_CH4     "tim5_ch4"
>>>>>> +
>>>>>> +#define TIM6_TRGO    "tim6_trgo"
>>>>>> +
>>>>>> +#define TIM7_TRGO    "tim7_trgo"
>>>>>> +
>>>>>> +#define TIM8_TRGO    "tim8_trgo"
>>>>>> +#define TIM8_CH1     "tim8_ch1"
>>>>>> +#define TIM8_CH2     "tim8_ch2"
>>>>>> +#define TIM8_CH3     "tim8_ch3"
>>>>>> +#define TIM8_CH4     "tim8_ch4"
>>>>>> +
>>>>>> +#define TIM9_TRGO    "tim9_trgo"
>>>>>> +#define TIM9_CH1     "tim9_ch1"
>>>>>> +#define TIM9_CH2     "tim9_ch2"
>>>>>> +
>>>>>> +#define TIM12_TRGO   "tim12_trgo"
>>>>>> +#define TIM12_CH1    "tim12_ch1"
>>>>>> +#define TIM12_CH2    "tim12_ch2"
>>>>>> +
>>>>>> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
>>>>>> +
>>>>>> +#endif
>>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>>
>> --
>> Benjamin Gaignard
>>
>> Graphic Study Group
>>
>> Linaro.org │ Open source software for ARM SoCs
>>
>> Follow Linaro: Facebook | Twitter | Blog

Patch

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
new file mode 100644
index 0000000..26583dd
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
@@ -0,0 +1,55 @@ 
+What:		/sys/bus/iio/devices/iio:deviceX/master_mode_available
+KernelVersion:	4.10
+Contact:	[e-mail]
+Description:
+		Reading returns the list possible master modes which are:
+		- "reset"     :	The UG bit from the TIMx_EGR register is used as trigger output (TRGO).
+		- "enable"    : The Counter Enable signal CNT_EN is used as trigger output.
+		- "update"    : The update event is selected as trigger output.
+				For instance a master timer can then be used as a prescaler for a slave timer.
+		- "compare_pulse" : The trigger output send a positive pulse when the CC1IF flag is to be set.
+		- "OC1REF"    : OC1REF signal is used as trigger output.
+		- "OC2REF"    : OC2REF signal is used as trigger output.
+		- "OC3REF"    : OC3REF signal is used as trigger output.
+		- "OC4REF"    : OC4REF signal is used as trigger output.
+
+What:		/sys/bus/iio/devices/iio:deviceX/master_mode
+KernelVersion:	4.10
+Contact:	[e-mail]
+Description:
+		Reading returns the current master modes.
+		Writing set the master mode
+
+What:		/sys/bus/iio/devices/iio:deviceX/slave_mode_available
+KernelVersion:	4.10
+Contact:	[e-mail]
+Description:
+		Reading returns the list possible slave modes which are:
+		- "disabled"  : The prescaler is clocked directly by the internal clock.
+		- "encoder_1" : Counter counts up/down on TI2FP1 edge depending on TI1FP2 level.
+		- "encoder_2" : Counter counts up/down on TI1FP2 edge depending on TI2FP1 level.
+		- "encoder_3" : Counter counts up/down on both TI1FP1 and TI2FP2 edges depending
+				on the level of the other input.
+		- "reset"     : Rising edge of the selected trigger input reinitializes the counter
+				and generates an update of the registers.
+		- "gated"     : The counter clock is enabled when the trigger input is high.
+				The counter stops (but is not reset) as soon as the trigger becomes low.
+				Both start and stop of the counter are controlled.
+		- "trigger"   : The counter starts at a rising edge of the trigger TRGI (but it is not
+				reset). Only the start of the counter is controlled.
+		- "external_clock": Rising edges of the selected trigger (TRGI) clock the counter.
+
+What:		/sys/bus/iio/devices/iio:deviceX/slave_mode
+KernelVersion:	4.10
+Contact:	[e-mail]
+Description:
+		Reading returns the current slave mode.
+		Writing set the slave mode
+
+What:		/sys/bus/iio/devices/triggerX/sampling_frequency
+KernelVersion:	4.10
+Contact:	[e-mail]
+Description:
+		Reading returns the current sampling frequency.
+		Writing an value different of 0 set and start sampling.
+		Writing 0 stop sampling.
diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
index 6743b18..2de2a80 100644
--- a/drivers/iio/Kconfig
+++ b/drivers/iio/Kconfig
@@ -90,5 +90,5 @@  source "drivers/iio/potentiometer/Kconfig"
 source "drivers/iio/pressure/Kconfig"
 source "drivers/iio/proximity/Kconfig"
 source "drivers/iio/temperature/Kconfig"
-
+source "drivers/iio/timer/Kconfig"
 endif # IIO
diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
index 87e4c43..b797c08 100644
--- a/drivers/iio/Makefile
+++ b/drivers/iio/Makefile
@@ -32,4 +32,5 @@  obj-y += potentiometer/
 obj-y += pressure/
 obj-y += proximity/
 obj-y += temperature/
+obj-y += timer/
 obj-y += trigger/
diff --git a/drivers/iio/timer/Kconfig b/drivers/iio/timer/Kconfig
new file mode 100644
index 0000000..e3c21f2
--- /dev/null
+++ b/drivers/iio/timer/Kconfig
@@ -0,0 +1,13 @@ 
+#
+# Timers drivers
+
+menu "Timers"
+
+config IIO_STM32_TIMER_TRIGGER
+	tristate "STM32 Timer Trigger"
+	depends on (ARCH_STM32 && OF && MFD_STM32_TIMERS) || COMPILE_TEST
+	select IIO_TRIGGERED_EVENT
+	help
+	  Select this option to enable STM32 Timer Trigger
+
+endmenu
diff --git a/drivers/iio/timer/Makefile b/drivers/iio/timer/Makefile
new file mode 100644
index 0000000..4ad95ec9
--- /dev/null
+++ b/drivers/iio/timer/Makefile
@@ -0,0 +1 @@ 
+obj-$(CONFIG_IIO_STM32_TIMER_TRIGGER) += stm32-timer-trigger.o
diff --git a/drivers/iio/timer/stm32-timer-trigger.c b/drivers/iio/timer/stm32-timer-trigger.c
new file mode 100644
index 0000000..8d16e8f
--- /dev/null
+++ b/drivers/iio/timer/stm32-timer-trigger.c
@@ -0,0 +1,466 @@ 
+/*
+ * Copyright (C) STMicroelectronics 2016
+ *
+ * Author: Benjamin Gaignard <[e-mail]>
+ *
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/timer/stm32-timer-trigger.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/triggered_event.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/stm32-timers.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define MAX_TRIGGERS 6
+#define MAX_VALIDS 5
+
+/* List the triggers created by each timer */
+static const void *triggers_table[][MAX_TRIGGERS] = {
+	{ TIM1_TRGO, TIM1_CH1, TIM1_CH2, TIM1_CH3, TIM1_CH4,},
+	{ TIM2_TRGO, TIM2_CH1, TIM2_CH2, TIM2_CH3, TIM2_CH4,},
+	{ TIM3_TRGO, TIM3_CH1, TIM3_CH2, TIM3_CH3, TIM3_CH4,},
+	{ TIM4_TRGO, TIM4_CH1, TIM4_CH2, TIM4_CH3, TIM4_CH4,},
+	{ TIM5_TRGO, TIM5_CH1, TIM5_CH2, TIM5_CH3, TIM5_CH4,},
+	{ TIM6_TRGO,},
+	{ TIM7_TRGO,},
+	{ TIM8_TRGO, TIM8_CH1, TIM8_CH2, TIM8_CH3, TIM8_CH4,},
+	{ TIM9_TRGO, TIM9_CH1, TIM9_CH2,},
+	{ TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
+};
+
+/* List the triggers accepted by each timer */
+static const void *valids_table[][MAX_VALIDS] = {
+	{ TIM5_TRGO, TIM2_TRGO, TIM4_TRGO, TIM3_TRGO,},
+	{ TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
+	{ TIM1_TRGO, TIM8_TRGO, TIM5_TRGO, TIM4_TRGO,},
+	{ TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
+	{ TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
+	{ }, /* timer 6 */
+	{ }, /* timer 7 */
+	{ TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
+	{ TIM2_TRGO, TIM3_TRGO,},
+	{ TIM4_TRGO, TIM5_TRGO,},
+};
+
+struct stm32_timer_trigger {
+	struct device *dev;
+	struct regmap *regmap;
+	struct clk *clk;
+	u32 max_arr;
+	const void *triggers;
+	const void *valids;
+};
+
+static int stm32_timer_start(struct stm32_timer_trigger *priv,
+			     unsigned int frequency)
+{
+	unsigned long long prd, div;
+	int prescaler = 0;
+	u32 ccer, cr1;
+
+	/* Period and prescaler values depends of clock rate */
+	div = (unsigned long long)clk_get_rate(priv->clk);
+
+	do_div(div, frequency);
+
+	prd = div;
+
+	/*
+	 * Increase prescaler value until we get a result that fit
+	 * with auto reload register maximum value.
+	 */
+	while (div > priv->max_arr) {
+		prescaler++;
+		div = prd;
+		do_div(div, (prescaler + 1));
+	}
+	prd = div;
+
+	if (prescaler > MAX_TIM_PSC) {
+		dev_err(priv->dev, "prescaler exceeds the maximum value\n");
+		return -EINVAL;
+	}
+
+	/* Check if nobody else use the timer */
+	regmap_read(priv->regmap, TIM_CCER, &ccer);
+	if (ccer & TIM_CCER_CCXE)
+		return -EBUSY;
+
+	regmap_read(priv->regmap, TIM_CR1, &cr1);
+	if (!(cr1 & TIM_CR1_CEN))
+		clk_enable(priv->clk);
+
+	regmap_write(priv->regmap, TIM_PSC, prescaler);
+	regmap_write(priv->regmap, TIM_ARR, prd - 1);
+	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
+
+	/* Force master mode to update mode */
+	regmap_update_bits(priv->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
+
+	/* Make sure that registers are updated */
+	regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
+
+	/* Enable controller */
+	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
+
+	return 0;
+}
+
+static void stm32_timer_stop(struct stm32_timer_trigger *priv)
+{
+	u32 ccer, cr1;
+
+	regmap_read(priv->regmap, TIM_CCER, &ccer);
+	if (ccer & TIM_CCER_CCXE)
+		return;
+
+	regmap_read(priv->regmap, TIM_CR1, &cr1);
+	if (cr1 & TIM_CR1_CEN)
+		clk_disable(priv->clk);
+
+	/* Stop timer */
+	regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
+	regmap_write(priv->regmap, TIM_PSC, 0);
+	regmap_write(priv->regmap, TIM_ARR, 0);
+}
+
+static ssize_t stm32_tt_store_frequency(struct device *dev,
+					struct device_attribute *attr,
+					const char *buf, size_t len)
+{
+	struct iio_trigger *trig = to_iio_trigger(dev);
+	struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
+	unsigned int freq;
+	int ret;
+
+	ret = kstrtouint(buf, 10, &freq);
+	if (ret)
+		return ret;
+
+	if (freq == 0) {
+		stm32_timer_stop(priv);
+	} else {
+		ret = stm32_timer_start(priv, freq);
+		if (ret)
+			return ret;
+	}
+
+	return len;
+}
+
+static ssize_t stm32_tt_read_frequency(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct iio_trigger *trig = to_iio_trigger(dev);
+	struct stm32_timer_trigger *priv = iio_trigger_get_drvdata(trig);
+	u32 psc, arr, cr1;
+	unsigned long long freq = 0;
+
+	regmap_read(priv->regmap, TIM_CR1, &cr1);
+	regmap_read(priv->regmap, TIM_PSC, &psc);
+	regmap_read(priv->regmap, TIM_ARR, &arr);
+
+	if (psc && arr && (cr1 & TIM_CR1_CEN)) {
+		freq = (unsigned long long)clk_get_rate(priv->clk);
+		do_div(freq, psc);
+		do_div(freq, arr);
+	}
+
+	return sprintf(buf, "%d\n", (unsigned int)freq);
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ(0660,
+			      stm32_tt_read_frequency,
+			      stm32_tt_store_frequency);
+
+static struct attribute *stm32_trigger_attrs[] = {
+	&iio_dev_attr_sampling_frequency.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group stm32_trigger_attr_group = {
+	.attrs = stm32_trigger_attrs,
+};
+
+static const struct attribute_group *stm32_trigger_attr_groups[] = {
+	&stm32_trigger_attr_group,
+	NULL,
+};
+
+static char *master_mode_table[] = {
+	"reset",
+	"enable",
+	"update",
+	"compare_pulse",
+	"OC1REF",
+	"OC2REF",
+	"OC3REF",
+	"OC4REF"
+};
+
+static ssize_t stm32_tt_show_master_mode(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	u32 cr2;
+
+	regmap_read(priv->regmap, TIM_CR2, &cr2);
+	cr2 = (cr2 & TIM_CR2_MMS) >> TIM_CR2_MMS_SHIFT;
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
+}
+
+static ssize_t stm32_tt_store_master_mode(struct device *dev,
+					  struct device_attribute *attr,
+					  const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
+		if (!strncmp(master_mode_table[i], buf,
+			     strlen(master_mode_table[i]))) {
+			regmap_update_bits(priv->regmap, TIM_CR2,
+					   TIM_CR2_MMS, i << TIM_CR2_MMS_SHIFT);
+			return len;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static IIO_CONST_ATTR(master_mode_available,
+	"reset enable update compare_pulse OC1REF OC2REF OC3REF OC4REF");
+
+static IIO_DEVICE_ATTR(master_mode, 0660,
+		       stm32_tt_show_master_mode,
+		       stm32_tt_store_master_mode,
+		       0);
+
+static char *slave_mode_table[] = {
+	"disabled",
+	"encoder_1",
+	"encoder_2",
+	"encoder_3",
+	"reset",
+	"gated",
+	"trigger",
+	"external_clock",
+};
+
+static ssize_t stm32_tt_show_slave_mode(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	u32 smcr;
+
+	regmap_read(priv->regmap, TIM_SMCR, &smcr);
+	smcr &= TIM_SMCR_SMS;
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
+}
+
+static ssize_t stm32_tt_store_slave_mode(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t len)
+{
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(slave_mode_table); i++) {
+		if (!strncmp(slave_mode_table[i], buf,
+			     strlen(slave_mode_table[i]))) {
+			regmap_update_bits(priv->regmap,
+					   TIM_SMCR, TIM_SMCR_SMS, i);
+			return len;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static IIO_CONST_ATTR(slave_mode_available,
+"disabled encoder_1 encoder_2 encoder_3 reset gated trigger external_clock");
+
+static IIO_DEVICE_ATTR(slave_mode, 0660,
+		       stm32_tt_show_slave_mode,
+		       stm32_tt_store_slave_mode,
+		       0);
+
+static struct attribute *stm32_timer_attrs[] = {
+	&iio_dev_attr_master_mode.dev_attr.attr,
+	&iio_const_attr_master_mode_available.dev_attr.attr,
+	&iio_dev_attr_slave_mode.dev_attr.attr,
+	&iio_const_attr_slave_mode_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group stm32_timer_attr_group = {
+	.attrs = stm32_timer_attrs,
+};
+
+static const struct iio_trigger_ops timer_trigger_ops = {
+	.owner = THIS_MODULE,
+};
+
+static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
+{
+	int ret;
+	const char * const *cur = priv->triggers;
+
+	while (cur && *cur) {
+		struct iio_trigger *trig;
+
+		trig = devm_iio_trigger_alloc(priv->dev, "%s", *cur);
+		if  (!trig)
+			return -ENOMEM;
+
+		trig->dev.parent = priv->dev->parent;
+		trig->ops = &timer_trigger_ops;
+		trig->dev.groups = stm32_trigger_attr_groups;
+		iio_trigger_set_drvdata(trig, priv);
+
+		ret = devm_iio_trigger_register(priv->dev, trig);
+		if (ret)
+			return ret;
+		cur++;
+	}
+
+	return 0;
+}
+
+/**
+ * is_stm32_timer_trigger
+ * @trig: trigger to be checked
+ *
+ * return true if the trigger is a valid stm32 iio timer trigger
+ * either return false
+ */
+bool is_stm32_timer_trigger(struct iio_trigger *trig)
+{
+	return (trig->ops == &timer_trigger_ops);
+}
+EXPORT_SYMBOL(is_stm32_timer_trigger);
+
+static int stm32_validate_trigger(struct iio_dev *indio_dev,
+				  struct iio_trigger *trig)
+{
+	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
+	const char * const *cur = priv->valids;
+	unsigned int i = 0;
+
+	if (!is_stm32_timer_trigger(trig))
+		return -EINVAL;
+
+	while (cur && *cur) {
+		if (!strncmp(trig->name, *cur, strlen(trig->name))) {
+			regmap_update_bits(priv->regmap,
+					   TIM_SMCR, TIM_SMCR_TS,
+					   i << TIM_SMCR_TS_SHIFT);
+			return 0;
+		}
+		cur++;
+		i++;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info stm32_trigger_info = {
+	.driver_module = THIS_MODULE,
+	.validate_trigger = stm32_validate_trigger,
+	.attrs = &stm32_timer_attr_group,
+};
+
+static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
+{
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev,
+					  sizeof(struct stm32_timer_trigger));
+	if (!indio_dev)
+		return NULL;
+
+	indio_dev->name = dev_name(dev);
+	indio_dev->dev.parent = dev;
+	indio_dev->info = &stm32_trigger_info;
+	indio_dev->modes = INDIO_EVENT_TRIGGERED;
+	indio_dev->num_channels = 0;
+	indio_dev->dev.of_node = dev->of_node;
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret)
+		return NULL;
+
+	return iio_priv(indio_dev);
+}
+
+static int stm32_timer_trigger_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct stm32_timer_trigger *priv;
+	struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
+	unsigned int index;
+	int ret;
+
+	if (of_property_read_u32(dev->of_node, "reg", &index))
+		return -EINVAL;
+
+	if (index >= ARRAY_SIZE(triggers_table))
+		return -EINVAL;
+
+	/* Create an IIO device only if we have triggers to be validated */
+	if (*valids_table[index])
+		priv = stm32_setup_iio_device(dev);
+	else
+		priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = dev;
+	priv->regmap = ddata->regmap;
+	priv->clk = ddata->clk;
+	priv->max_arr = ddata->max_arr;
+	priv->triggers = triggers_table[index];
+	priv->valids = valids_table[index];
+
+	ret = stm32_setup_iio_triggers(priv);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+}
+
+static const struct of_device_id stm32_trig_of_match[] = {
+	{ .compatible = "st,stm32-timer-trigger", },
+	{ /* end node */ },
+};
+MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
+
+static struct platform_driver stm32_timer_trigger_driver = {
+	.probe = stm32_timer_trigger_probe,
+	.driver = {
+		.name = "stm32-timer-trigger",
+		.of_match_table = stm32_trig_of_match,
+	},
+};
+module_platform_driver(stm32_timer_trigger_driver);
+
+MODULE_ALIAS("platform: stm32-timer-trigger");
+MODULE_DESCRIPTION("STMicroelectronics STM32 Timer Trigger driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/trigger/Kconfig b/drivers/iio/trigger/Kconfig
index 809b2e7..f2af4fe 100644
--- a/drivers/iio/trigger/Kconfig
+++ b/drivers/iio/trigger/Kconfig
@@ -46,5 +46,4 @@  config IIO_SYSFS_TRIGGER
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called iio-trig-sysfs.
-
 endmenu
diff --git a/include/linux/iio/timer/stm32-timer-trigger.h b/include/linux/iio/timer/stm32-timer-trigger.h
new file mode 100644
index 0000000..55535ae
--- /dev/null
+++ b/include/linux/iio/timer/stm32-timer-trigger.h
@@ -0,0 +1,62 @@ 
+/*
+ * Copyright (C) STMicroelectronics 2016
+ *
+ * Author: Benjamin Gaignard <[e-mail]>
+ *
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#ifndef _STM32_TIMER_TRIGGER_H_
+#define _STM32_TIMER_TRIGGER_H_
+
+#define TIM1_TRGO	"tim1_trgo"
+#define TIM1_CH1	"tim1_ch1"
+#define TIM1_CH2	"tim1_ch2"
+#define TIM1_CH3	"tim1_ch3"
+#define TIM1_CH4	"tim1_ch4"
+
+#define TIM2_TRGO	"tim2_trgo"
+#define TIM2_CH1	"tim2_ch1"
+#define TIM2_CH2	"tim2_ch2"
+#define TIM2_CH3	"tim2_ch3"
+#define TIM2_CH4	"tim2_ch4"
+
+#define TIM3_TRGO	"tim3_trgo"
+#define TIM3_CH1	"tim3_ch1"
+#define TIM3_CH2	"tim3_ch2"
+#define TIM3_CH3	"tim3_ch3"
+#define TIM3_CH4	"tim3_ch4"
+
+#define TIM4_TRGO	"tim4_trgo"
+#define TIM4_CH1	"tim4_ch1"
+#define TIM4_CH2	"tim4_ch2"
+#define TIM4_CH3	"tim4_ch3"
+#define TIM4_CH4	"tim4_ch4"
+
+#define TIM5_TRGO	"tim5_trgo"
+#define TIM5_CH1	"tim5_ch1"
+#define TIM5_CH2	"tim5_ch2"
+#define TIM5_CH3	"tim5_ch3"
+#define TIM5_CH4	"tim5_ch4"
+
+#define TIM6_TRGO	"tim6_trgo"
+
+#define TIM7_TRGO	"tim7_trgo"
+
+#define TIM8_TRGO	"tim8_trgo"
+#define TIM8_CH1	"tim8_ch1"
+#define TIM8_CH2	"tim8_ch2"
+#define TIM8_CH3	"tim8_ch3"
+#define TIM8_CH4	"tim8_ch4"
+
+#define TIM9_TRGO	"tim9_trgo"
+#define TIM9_CH1	"tim9_ch1"
+#define TIM9_CH2	"tim9_ch2"
+
+#define TIM12_TRGO	"tim12_trgo"
+#define TIM12_CH1	"tim12_ch1"
+#define TIM12_CH2	"tim12_ch2"
+
+bool is_stm32_timer_trigger(struct iio_trigger *trig);
+
+#endif