[v3,6/7] IIO: add STM32 timer trigger driver

Commit Message

Benjamin Gaignard Dec. 2, 2016, 10:17 a.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/dt-bindings/iio/timer/st,stm32-iio-timer.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 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          |  47 ++
 drivers/iio/Kconfig                                |   2 +-
 drivers/iio/Makefile                               |   1 +
 drivers/iio/timer/Kconfig                          |  15 +
 drivers/iio/timer/Makefile                         |   1 +
 drivers/iio/timer/stm32-timer-trigger.c            | 477 +++++++++++++++++++++
 drivers/iio/trigger/Kconfig                        |   1 -
 .../iio/timer/st,stm32-timer-triggers.h            |  60 +++
 include/linux/iio/timer/stm32-timer-trigger.h      |  16 +
 9 files changed, 618 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/dt-bindings/iio/timer/st,stm32-timer-triggers.h
 create mode 100644 include/linux/iio/timer/stm32-timer-trigger.h

Comments

Lee Jones Dec. 2, 2016, 1:57 p.m. UTC | #1

On Fri, 02 Dec 2016, 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/dt-bindings/iio/timer/st,stm32-iio-timer.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 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          |  47 ++
>  drivers/iio/Kconfig                                |   2 +-
>  drivers/iio/Makefile                               |   1 +
>  drivers/iio/timer/Kconfig                          |  15 +
>  drivers/iio/timer/Makefile                         |   1 +
>  drivers/iio/timer/stm32-timer-trigger.c            | 477 +++++++++++++++++++++
>  drivers/iio/trigger/Kconfig                        |   1 -
>  .../iio/timer/st,stm32-timer-triggers.h            |  60 +++
>  include/linux/iio/timer/stm32-timer-trigger.h      |  16 +
>  9 files changed, 618 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/dt-bindings/iio/timer/st,stm32-timer-triggers.h
>  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..b70bb2a
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
> @@ -0,0 +1,47 @@
> +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
> 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..149a917
> --- /dev/null
> +++ b/drivers/iio/timer/Kconfig
> @@ -0,0 +1,15 @@
> +#
> +# Timers drivers
> +
> +menu "Timers"
> +
> +config IIO_STM32_TIMER_TRIGGER
> +	tristate "stm32 timer trigger"

"STM32 Timer Trigger"

> +	depends on ARCH_STM32
> +	depends on OF

Are these build or run time dependencies?

If they are only run-time, add "|| COMPILE_TEST".

> +	select IIO_TRIGGERED_EVENT
> +	select MFD_STM32_GP_TIMER
> +	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..0c51601
> --- /dev/null
> +++ b/drivers/iio/timer/stm32-timer-trigger.c
> @@ -0,0 +1,477 @@
> +/*
> + * stm32-iio-timer.c

Swap this out for a description.

Filenames have a habit of becoming out-of-date.

> + * Copyright (C) STMicroelectronics 2016

'\n'

> + * Author: Benjamin Gaignard <[e-mail]> for STMicroelectronics.

You don't need to put the "for" bit.  That's just what we do when
Linaro are writing drivers for other companies.  Your email address
says enough.

> + * 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-gptimer.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +#define DRIVER_NAME	"stm32-timer-trigger"

Just use the name in the correct places.  Defining device names is an
ugly practice IMHO.

> +#define MAX_MODES	8
> +
> +struct stm32_timer_trigger_dev {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct clk *clk;
> +	int irq;
> +	bool own_timer;
> +	unsigned int sampling_frequency;
> +	struct iio_trigger *active_trigger;
> +};
> +
> +static ssize_t _store_frequency(struct device *dev,

What's with the '_' naming scheme?

> +				struct device_attribute *attr,
> +				const char *buf, size_t len)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct stm32_timer_trigger_dev *stm32 = iio_trigger_get_drvdata(trig);
> +	unsigned int freq;
> +	int ret;
> +
> +	ret = kstrtouint(buf, 10, &freq);
> +	if (ret)
> +		return ret;

No bounds checking required?

> +	stm32->sampling_frequency = freq;

Where is this value placed into the registers?

> +	return len;
> +}
> +
> +static ssize_t _read_frequency(struct device *dev,
> +			       struct device_attribute *attr, char *buf)
> +{
> +	struct iio_trigger *trig = to_iio_trigger(dev);
> +	struct stm32_timer_trigger_dev *stm32 = iio_trigger_get_drvdata(trig);
> +	unsigned long long freq = stm32->sampling_frequency;
> +	u32 psc, arr, cr1;
> +
> +	regmap_read(stm32->regmap, TIM_CR1, &cr1);
> +	regmap_read(stm32->regmap, TIM_PSC, &psc);
> +	regmap_read(stm32->regmap, TIM_ARR, &arr);
> +
> +	if (psc && arr && (cr1 & TIM_CR1_CEN)) {
> +		freq = (unsigned long long)clk_get_rate(stm32->clk);
> +		do_div(freq, psc);
> +		do_div(freq, arr);
> +	}
> +
> +	return sprintf(buf, "%d\n", (unsigned int)freq);
> +}
> +
> +static IIO_DEV_ATTR_SAMP_FREQ(0660, _read_frequency, _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,
> +};

A lot of generic code here.

Are there macros that could help with this?

> +static char *master_mode_table[] = {
> +	"reset",
> +	"enable",
> +	"update",
> +	"compare_pulse",
> +	"OC1REF",
> +	"OC2REF",
> +	"OC3REF",
> +	"OC4REF"
> +};
> +
> +static

Why the line break here?

[and the ones below]

> +ssize_t _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_dev *stm32 = iio_priv(indio_dev);
> +	u32 cr2;
> +
> +	regmap_read(stm32->regmap, TIM_CR2, &cr2);
> +	cr2 = (cr2 >> 4) & 0x7;

Define these SHIFT and MASK values.

> +	return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
> +}
> +
> +static
> +ssize_t _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_dev *stm32 = 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(stm32->regmap, TIM_CR2,
> +					   TIM_CR2_MMS, i << 4);

Define all of the SHIFT and MASK values in this set.

> +			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,
> +		       _show_master_mode,
> +		       _store_master_mode,
> +		       0);
> +
> +static char *slave_mode_table[] = {
> +	"disabled",
> +	"encoder_1",
> +	"encoder_2",
> +	"encoder_3",
> +	"reset",
> +	"gated",
> +	"trigger",
> +	"external_clock",
> +};
> +
> +static
> +ssize_t _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_dev *stm32 = iio_priv(indio_dev);
> +	u32 smcr;
> +
> +	regmap_read(stm32->regmap, TIM_SMCR, &smcr);
> +	smcr &= 0x7;
> +
> +	return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
> +}
> +
> +static
> +ssize_t _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_dev *stm32 = 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(stm32->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,
> +		       _show_slave_mode,
> +		       _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 int stm32_timer_start(struct stm32_timer_trigger_dev *stm32)
> +{
> +	unsigned long long prd, div;
> +	int prescaler = 0;
> +	u32 max_arr = 0xFFFF, cr1;

Since this is const, it'll be better of as a define.

> +	if (stm32->sampling_frequency == 0)
> +		return 0;

Is this okay?  Or is this an error?

> +	/* Period and prescaler values depends of clock rate */
> +	div = (unsigned long long)clk_get_rate(stm32->clk);
> +
> +	do_div(div, stm32->sampling_frequency);
> +
> +	prd = div;
> +
> +	while (div > max_arr) {
> +		prescaler++;
> +		div = prd;
> +		do_div(div, (prescaler + 1));
> +	}
> +	prd = div;

Best to place a comment here.  Saves the reader having to work it out.

> +	if (prescaler > MAX_TIM_PSC) {
> +		dev_err(stm32->dev, "prescaler exceeds the maximum value\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Check that we own the timer */
> +	regmap_read(stm32->regmap, TIM_CR1, &cr1);
> +	if ((cr1 & TIM_CR1_CEN) && !stm32->own_timer)
> +		return -EBUSY;

What happens if the timer is already enabled and you do own it?

I guess this *re*-starts it?

> +	if (!stm32->own_timer) {
> +		stm32->own_timer = true;
> +		clk_enable(stm32->clk);
> +	}

At the very least you're going to require some shared locking here.

At best you should have a shared "device held" flag.

> +	regmap_write(stm32->regmap, TIM_PSC, prescaler);
> +	regmap_write(stm32->regmap, TIM_ARR, prd - 1);
> +	regmap_update_bits(stm32->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
> +
> +	/* Force master mode to update mode */
> +	regmap_update_bits(stm32->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
> +
> +	/* Make sure that registers are updated */
> +	regmap_update_bits(stm32->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
> +
> +	/* Enable interrupt */
> +	regmap_write(stm32->regmap, TIM_SR, 0);
> +	regmap_update_bits(stm32->regmap, TIM_DIER, TIM_DIER_UIE, TIM_DIER_UIE);
> +
> +	/* Enable controller */
> +	regmap_update_bits(stm32->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
> +
> +	return 0;
> +}
> +
> +static int stm32_timer_stop(struct stm32_timer_trigger_dev *stm32)
> +{
> +	if (!stm32->own_timer)
> +		return 0;
> +
> +	/* Stop timer */
> +	regmap_update_bits(stm32->regmap, TIM_DIER, TIM_DIER_UIE, 0);
> +	regmap_update_bits(stm32->regmap, TIM_CR1, TIM_CR1_CEN, 0);
> +	regmap_write(stm32->regmap, TIM_PSC, 0);
> +	regmap_write(stm32->regmap, TIM_ARR, 0);
> +
> +	clk_disable(stm32->clk);
> +
> +	stm32->own_timer = false;
> +	stm32->active_trigger = NULL;
> +
> +	return 0;
> +}
> +
> +static int stm32_set_trigger_state(struct iio_trigger *trig, bool state)
> +{
> +	struct stm32_timer_trigger_dev *stm32 = iio_trigger_get_drvdata(trig);
> +
> +	stm32->active_trigger = trig;
> +
> +	if (state)
> +		return stm32_timer_start(stm32);
> +	else
> +		return stm32_timer_stop(stm32);
> +}
> +
> +static irqreturn_t stm32_timer_irq_handler(int irq, void *private)
> +{
> +	struct stm32_timer_trigger_dev *stm32 = private;
> +	u32 sr;
> +
> +	regmap_read(stm32->regmap, TIM_SR, &sr);
> +	regmap_write(stm32->regmap, TIM_SR, 0);
> +
> +	if ((sr & TIM_SR_UIF) && stm32->active_trigger)
> +		iio_trigger_poll(stm32->active_trigger);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static const struct iio_trigger_ops timer_trigger_ops = {
> +	.owner = THIS_MODULE,
> +	.set_trigger_state = stm32_set_trigger_state,
> +};
> +
> +static int stm32_setup_iio_triggers(struct stm32_timer_trigger_dev *stm32)
> +{
> +	int ret;
> +	struct property *p;
> +	const char *cur = NULL;
> +
> +	p = of_find_property(stm32->dev->of_node,
> +			     "st,output-triggers-names", NULL);
> +
> +	while ((cur = of_prop_next_string(p, cur)) != NULL) {
> +		struct iio_trigger *trig;
> +
> +		trig = devm_iio_trigger_alloc(stm32->dev, "%s", cur);
> +		if  (!trig)
> +			return -ENOMEM;
> +
> +		trig->dev.parent = stm32->dev->parent;
> +		trig->ops = &timer_trigger_ops;
> +		trig->dev.groups = stm32_trigger_attr_groups;
> +		iio_trigger_set_drvdata(trig, stm32);
> +
> +		ret = devm_iio_trigger_register(stm32->dev, trig);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	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_dev *dev = iio_priv(indio_dev);
> +	int ret;
> +
> +	if (!is_stm32_timer_trigger(trig))
> +		return -EINVAL;
> +
> +	ret = of_property_match_string(dev->dev->of_node,
> +				       "st,input-triggers-names",
> +				       trig->name);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	regmap_update_bits(dev->regmap, TIM_SMCR, TIM_SMCR_TS, ret << 4);
> +
> +	return 0;
> +}
> +
> +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_dev *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_dev));

Did you run checkpatch.pl?

> +	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 = iio_triggered_event_setup(indio_dev,
> +					NULL,
> +					stm32_timer_irq_handler);
> +	if (ret)
> +		return NULL;

Return ERR_PTR(ret).

> +	ret = devm_iio_device_register(dev, indio_dev);
> +	if (ret) {
> +		iio_triggered_event_cleanup(indio_dev);
> +		return NULL;

Return ERR_PTR(ret).

> +	}
> +
> +	return iio_priv(indio_dev);
> +}
> +
> +static int stm32_timer_trigger_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct stm32_timer_trigger_dev *stm32;
> +	struct stm32_gptimer_dev *mfd = dev_get_drvdata(pdev->dev.parent);
> +	int ret;
> +
> +	stm32 = stm32_setup_iio_device(dev);
> +	if (!stm32)
> +		return -ENOMEM;

Return stm32.

> +	stm32->dev = dev;
> +	stm32->regmap = mfd->regmap;
> +	stm32->clk = mfd->clk;
> +
> +	stm32->irq = platform_get_irq(pdev, 0);
> +	if (stm32->irq < 0)
> +		return -EINVAL;

return stm32->irq.

> +	ret = devm_request_irq(stm32->dev, stm32->irq,
> +			       stm32_timer_irq_handler, IRQF_SHARED,
> +			       "timer_event", stm32);
> +	if (ret)
> +		return ret;
> +
> +	ret = stm32_setup_iio_triggers(stm32);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, stm32);
> +
> +	return 0;
> +}
> +
> +static int stm32_timer_trigger_remove(struct platform_device *pdev)
> +{
> +	struct stm32_timer_trigger_dev *stm32 = platform_get_drvdata(pdev);
> +
> +	iio_triggered_event_cleanup((struct iio_dev *)stm32);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id stm32_trig_of_match[] = {
> +	{
> +		.compatible = "st,stm32-timer-trigger",
> +	},
> +};

Make this one line.

	{ .compatible = "st,stm32-timer-trigger" },

> +MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
> +
> +static struct platform_driver stm32_timer_trigger_driver = {
> +	.probe = stm32_timer_trigger_probe,
> +	.remove = stm32_timer_trigger_remove,
> +	.driver = {
> +		.name = DRIVER_NAME,

Yuk!

> +		.of_match_table = stm32_trig_of_match,
> +	},
> +};
> +module_platform_driver(stm32_timer_trigger_driver);
> +
> +MODULE_ALIAS("platform:" DRIVER_NAME);
> +MODULE_DESCRIPTION("STMicroelectronics STM32 timer trigger driver");
> +MODULE_LICENSE("GPL");

I thought this was "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/dt-bindings/iio/timer/st,stm32-timer-triggers.h b/include/dt-bindings/iio/timer/st,stm32-timer-triggers.h
> new file mode 100644
> index 0000000..a13db63
> --- /dev/null
> +++ b/include/dt-bindings/iio/timer/st,stm32-timer-triggers.h
> @@ -0,0 +1,60 @@
> +/*
> + * st,stm32-timer-triggers.h
> + * Copyright (C) STMicroelectronics 2016
> + * Author: Benjamin Gaignard <[e-mail]> for STMicroelectronics.
> + * License terms:  GNU General Public License (GPL), version 2
> + */

Same comments as the top header.

> +#ifndef _DT_BINDINGS_STM32_TIMER_TRIGGERS_H_
> +#define _DT_BINDINGS_STM32_TIMER_TRIGGERS_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"

Grim!

uint8 valid_timers[]   = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 12 };
uint8 valid_channels[] = { 0, 1, 2, 3, 4 };

> +#endif
> 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..c22fb3b
> --- /dev/null
> +++ b/include/linux/iio/timer/stm32-timer-trigger.h
> @@ -0,0 +1,16 @@
> +/*
> + * stm32-timer-trigger.h
> + * Copyright (C) STMicroelectronics 2016
> + * Author: Benjamin Gaignard <[e-mail]> for STMicroelectronics.
> + * License terms:  GNU General Public License (GPL), version 2
> + */

Same comments as the top header.

> +#ifndef _STM32_TIMER_TRIGGER_H_
> +#define _STM32_TIMER_TRIGGER_H_
> +
> +#include <dt-bindings/iio/timer/st,stm32-timer-triggers.h>
> +
> +bool is_stm32_timer_trigger(struct iio_trigger *trig);
> +
> +#endif

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..b70bb2a
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
@@ -0,0 +1,47 @@ 
+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
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..149a917
--- /dev/null
+++ b/drivers/iio/timer/Kconfig
@@ -0,0 +1,15 @@ 
+#
+# Timers drivers
+
+menu "Timers"
+
+config IIO_STM32_TIMER_TRIGGER
+	tristate "stm32 timer trigger"
+	depends on ARCH_STM32
+	depends on OF
+	select IIO_TRIGGERED_EVENT
+	select MFD_STM32_GP_TIMER
+	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..0c51601
--- /dev/null
+++ b/drivers/iio/timer/stm32-timer-trigger.c
@@ -0,0 +1,477 @@ 
+/*
+ * stm32-iio-timer.c
+ *
+ * Copyright (C) STMicroelectronics 2016
+ * Author: Benjamin Gaignard <[e-mail]> for STMicroelectronics.
+ * 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-gptimer.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define DRIVER_NAME	"stm32-timer-trigger"
+#define MAX_MODES	8
+
+struct stm32_timer_trigger_dev {
+	struct device *dev;
+	struct regmap *regmap;
+	struct clk *clk;
+	int irq;
+	bool own_timer;
+	unsigned int sampling_frequency;
+	struct iio_trigger *active_trigger;
+};
+
+static ssize_t _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_dev *stm32 = iio_trigger_get_drvdata(trig);
+	unsigned int freq;
+	int ret;
+
+	ret = kstrtouint(buf, 10, &freq);
+	if (ret)
+		return ret;
+
+	stm32->sampling_frequency = freq;
+
+	return len;
+}
+
+static ssize_t _read_frequency(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct iio_trigger *trig = to_iio_trigger(dev);
+	struct stm32_timer_trigger_dev *stm32 = iio_trigger_get_drvdata(trig);
+	unsigned long long freq = stm32->sampling_frequency;
+	u32 psc, arr, cr1;
+
+	regmap_read(stm32->regmap, TIM_CR1, &cr1);
+	regmap_read(stm32->regmap, TIM_PSC, &psc);
+	regmap_read(stm32->regmap, TIM_ARR, &arr);
+
+	if (psc && arr && (cr1 & TIM_CR1_CEN)) {
+		freq = (unsigned long long)clk_get_rate(stm32->clk);
+		do_div(freq, psc);
+		do_div(freq, arr);
+	}
+
+	return sprintf(buf, "%d\n", (unsigned int)freq);
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ(0660, _read_frequency, _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 _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_dev *stm32 = iio_priv(indio_dev);
+	u32 cr2;
+
+	regmap_read(stm32->regmap, TIM_CR2, &cr2);
+	cr2 = (cr2 >> 4) & 0x7;
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", master_mode_table[cr2]);
+}
+
+static
+ssize_t _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_dev *stm32 = 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(stm32->regmap, TIM_CR2,
+					   TIM_CR2_MMS, i << 4);
+			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,
+		       _show_master_mode,
+		       _store_master_mode,
+		       0);
+
+static char *slave_mode_table[] = {
+	"disabled",
+	"encoder_1",
+	"encoder_2",
+	"encoder_3",
+	"reset",
+	"gated",
+	"trigger",
+	"external_clock",
+};
+
+static
+ssize_t _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_dev *stm32 = iio_priv(indio_dev);
+	u32 smcr;
+
+	regmap_read(stm32->regmap, TIM_SMCR, &smcr);
+	smcr &= 0x7;
+
+	return snprintf(buf, PAGE_SIZE, "%s\n", slave_mode_table[smcr]);
+}
+
+static
+ssize_t _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_dev *stm32 = 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(stm32->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,
+		       _show_slave_mode,
+		       _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 int stm32_timer_start(struct stm32_timer_trigger_dev *stm32)
+{
+	unsigned long long prd, div;
+	int prescaler = 0;
+	u32 max_arr = 0xFFFF, cr1;
+
+	if (stm32->sampling_frequency == 0)
+		return 0;
+
+	/* Period and prescaler values depends of clock rate */
+	div = (unsigned long long)clk_get_rate(stm32->clk);
+
+	do_div(div, stm32->sampling_frequency);
+
+	prd = div;
+
+	while (div > max_arr) {
+		prescaler++;
+		div = prd;
+		do_div(div, (prescaler + 1));
+	}
+	prd = div;
+
+	if (prescaler > MAX_TIM_PSC) {
+		dev_err(stm32->dev, "prescaler exceeds the maximum value\n");
+		return -EINVAL;
+	}
+
+	/* Check that we own the timer */
+	regmap_read(stm32->regmap, TIM_CR1, &cr1);
+	if ((cr1 & TIM_CR1_CEN) && !stm32->own_timer)
+		return -EBUSY;
+
+	if (!stm32->own_timer) {
+		stm32->own_timer = true;
+		clk_enable(stm32->clk);
+	}
+
+	regmap_write(stm32->regmap, TIM_PSC, prescaler);
+	regmap_write(stm32->regmap, TIM_ARR, prd - 1);
+	regmap_update_bits(stm32->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
+
+	/* Force master mode to update mode */
+	regmap_update_bits(stm32->regmap, TIM_CR2, TIM_CR2_MMS, 0x20);
+
+	/* Make sure that registers are updated */
+	regmap_update_bits(stm32->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
+
+	/* Enable interrupt */
+	regmap_write(stm32->regmap, TIM_SR, 0);
+	regmap_update_bits(stm32->regmap, TIM_DIER, TIM_DIER_UIE, TIM_DIER_UIE);
+
+	/* Enable controller */
+	regmap_update_bits(stm32->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
+
+	return 0;
+}
+
+static int stm32_timer_stop(struct stm32_timer_trigger_dev *stm32)
+{
+	if (!stm32->own_timer)
+		return 0;
+
+	/* Stop timer */
+	regmap_update_bits(stm32->regmap, TIM_DIER, TIM_DIER_UIE, 0);
+	regmap_update_bits(stm32->regmap, TIM_CR1, TIM_CR1_CEN, 0);
+	regmap_write(stm32->regmap, TIM_PSC, 0);
+	regmap_write(stm32->regmap, TIM_ARR, 0);
+
+	clk_disable(stm32->clk);
+
+	stm32->own_timer = false;
+	stm32->active_trigger = NULL;
+
+	return 0;
+}
+
+static int stm32_set_trigger_state(struct iio_trigger *trig, bool state)
+{
+	struct stm32_timer_trigger_dev *stm32 = iio_trigger_get_drvdata(trig);
+
+	stm32->active_trigger = trig;
+
+	if (state)
+		return stm32_timer_start(stm32);
+	else
+		return stm32_timer_stop(stm32);
+}
+
+static irqreturn_t stm32_timer_irq_handler(int irq, void *private)
+{
+	struct stm32_timer_trigger_dev *stm32 = private;
+	u32 sr;
+
+	regmap_read(stm32->regmap, TIM_SR, &sr);
+	regmap_write(stm32->regmap, TIM_SR, 0);
+
+	if ((sr & TIM_SR_UIF) && stm32->active_trigger)
+		iio_trigger_poll(stm32->active_trigger);
+
+	return IRQ_HANDLED;
+}
+
+static const struct iio_trigger_ops timer_trigger_ops = {
+	.owner = THIS_MODULE,
+	.set_trigger_state = stm32_set_trigger_state,
+};
+
+static int stm32_setup_iio_triggers(struct stm32_timer_trigger_dev *stm32)
+{
+	int ret;
+	struct property *p;
+	const char *cur = NULL;
+
+	p = of_find_property(stm32->dev->of_node,
+			     "st,output-triggers-names", NULL);
+
+	while ((cur = of_prop_next_string(p, cur)) != NULL) {
+		struct iio_trigger *trig;
+
+		trig = devm_iio_trigger_alloc(stm32->dev, "%s", cur);
+		if  (!trig)
+			return -ENOMEM;
+
+		trig->dev.parent = stm32->dev->parent;
+		trig->ops = &timer_trigger_ops;
+		trig->dev.groups = stm32_trigger_attr_groups;
+		iio_trigger_set_drvdata(trig, stm32);
+
+		ret = devm_iio_trigger_register(stm32->dev, trig);
+		if (ret)
+			return ret;
+	}
+
+	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_dev *dev = iio_priv(indio_dev);
+	int ret;
+
+	if (!is_stm32_timer_trigger(trig))
+		return -EINVAL;
+
+	ret = of_property_match_string(dev->dev->of_node,
+				       "st,input-triggers-names",
+				       trig->name);
+
+	if (ret < 0)
+		return ret;
+
+	regmap_update_bits(dev->regmap, TIM_SMCR, TIM_SMCR_TS, ret << 4);
+
+	return 0;
+}
+
+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_dev *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_dev));
+	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 = iio_triggered_event_setup(indio_dev,
+					NULL,
+					stm32_timer_irq_handler);
+	if (ret)
+		return NULL;
+
+	ret = devm_iio_device_register(dev, indio_dev);
+	if (ret) {
+		iio_triggered_event_cleanup(indio_dev);
+		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_dev *stm32;
+	struct stm32_gptimer_dev *mfd = dev_get_drvdata(pdev->dev.parent);
+	int ret;
+
+	stm32 = stm32_setup_iio_device(dev);
+	if (!stm32)
+		return -ENOMEM;
+
+	stm32->dev = dev;
+	stm32->regmap = mfd->regmap;
+	stm32->clk = mfd->clk;
+
+	stm32->irq = platform_get_irq(pdev, 0);
+	if (stm32->irq < 0)
+		return -EINVAL;
+
+	ret = devm_request_irq(stm32->dev, stm32->irq,
+			       stm32_timer_irq_handler, IRQF_SHARED,
+			       "timer_event", stm32);
+	if (ret)
+		return ret;
+
+	ret = stm32_setup_iio_triggers(stm32);
+	if (ret)
+		return ret;
+
+	platform_set_drvdata(pdev, stm32);
+
+	return 0;
+}
+
+static int stm32_timer_trigger_remove(struct platform_device *pdev)
+{
+	struct stm32_timer_trigger_dev *stm32 = platform_get_drvdata(pdev);
+
+	iio_triggered_event_cleanup((struct iio_dev *)stm32);
+
+	return 0;
+}
+
+static const struct of_device_id stm32_trig_of_match[] = {
+	{
+		.compatible = "st,stm32-timer-trigger",
+	},
+};
+MODULE_DEVICE_TABLE(of, stm32_trig_of_match);
+
+static struct platform_driver stm32_timer_trigger_driver = {
+	.probe = stm32_timer_trigger_probe,
+	.remove = stm32_timer_trigger_remove,
+	.driver = {
+		.name = DRIVER_NAME,
+		.of_match_table = stm32_trig_of_match,
+	},
+};
+module_platform_driver(stm32_timer_trigger_driver);
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_DESCRIPTION("STMicroelectronics STM32 timer trigger driver");
+MODULE_LICENSE("GPL");
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/dt-bindings/iio/timer/st,stm32-timer-triggers.h b/include/dt-bindings/iio/timer/st,stm32-timer-triggers.h
new file mode 100644
index 0000000..a13db63
--- /dev/null
+++ b/include/dt-bindings/iio/timer/st,stm32-timer-triggers.h
@@ -0,0 +1,60 @@ 
+/*
+ * st,stm32-timer-triggers.h
+ *
+ * Copyright (C) STMicroelectronics 2016
+ * Author: Benjamin Gaignard <[e-mail]> for STMicroelectronics.
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#ifndef _DT_BINDINGS_STM32_TIMER_TRIGGERS_H_
+#define _DT_BINDINGS_STM32_TIMER_TRIGGERS_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"
+
+#endif
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..c22fb3b
--- /dev/null
+++ b/include/linux/iio/timer/stm32-timer-trigger.h
@@ -0,0 +1,16 @@ 
+/*
+ * stm32-timer-trigger.h
+ *
+ * Copyright (C) STMicroelectronics 2016
+ * Author: Benjamin Gaignard <[e-mail]> for STMicroelectronics.
+ * License terms:  GNU General Public License (GPL), version 2
+ */
+
+#ifndef _STM32_TIMER_TRIGGER_H_
+#define _STM32_TIMER_TRIGGER_H_
+
+#include <dt-bindings/iio/timer/st,stm32-timer-triggers.h>
+
+bool is_stm32_timer_trigger(struct iio_trigger *trig);
+
+#endif