[3/3,v2] iio: adc: add a driver for Qualcomm PM8xxx HK/XOADC

Commit Message

Linus Walleij Dec. 15, 2016, 10:48 p.m. UTC

The Qualcomm PM8xxx PMICs contain a simpler ADC than its
successors (already in the kernel as qcom-spmi-adc.c):
the HK/XO ADC (Housekeeping/Chrystal oscillator ADC).

As far as I can understand this is equal to the PMICs
using SSBI transport and encompass PM8018, PM8038,
PM8058, PM8917 and PM8921, so this is shortly named
PM8xxx.

This ADC monitors a bunch of on-board voltages and the die
temperature of the PMIC itself, but it can also be routed
to convert a few external MPPs (multi-purpose pins). On
the APQ8060 DragonBoard this feature is used to let this
ADC convert an analog ALS (Ambient Light Sensor) voltage
signal from a Capella CM3605 ALS into a LUX value.

Developed and tested with APQ8060 DragonBoard based on
Ivan's driver. The SPMI VADC driver is quite different,
but share enough minor functionality that I have split
out to the common file in a previous patch.

Cc: [e-mail]
Cc: [e-mail]
Cc: Ivan T. Ivanov <[e-mail]>
Cc: Andy Gross <[e-mail]>
Cc: Bjorn Andersson <[e-mail]>
Cc: Stephen Boyd <[e-mail]>
Cc: Srinivas Kandagatla <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
---
ChangeLog v1->v2:
- Introduce a mutex to avoid different clients stepping on each others'
  toes
- Add an of_xlate function to be sure to match the right ADC
- Add all compatible strings, not just PM8058
---
 drivers/iio/adc/Kconfig             |  10 +
 drivers/iio/adc/Makefile            |   1 +
 drivers/iio/adc/qcom-pm8xxx-xoadc.c | 786 ++++++++++++++++++++++++++++++++++++
 3 files changed, 797 insertions(+)
 create mode 100644 drivers/iio/adc/qcom-pm8xxx-xoadc.c

Comments

Peter Meerwald-Stadler Dec. 16, 2016, 10:06 a.m. UTC | #1

On Thu, 15 Dec 2016, Linus Walleij wrote:

> The Qualcomm PM8xxx PMICs contain a simpler ADC than its
> successors (already in the kernel as qcom-spmi-adc.c):
> the HK/XO ADC (Housekeeping/Chrystal oscillator ADC).

crystal

some minor comments below

> 
> As far as I can understand this is equal to the PMICs
> using SSBI transport and encompass PM8018, PM8038,
> PM8058, PM8917 and PM8921, so this is shortly named
> PM8xxx.
> 
> This ADC monitors a bunch of on-board voltages and the die
> temperature of the PMIC itself, but it can also be routed
> to convert a few external MPPs (multi-purpose pins). On
> the APQ8060 DragonBoard this feature is used to let this
> ADC convert an analog ALS (Ambient Light Sensor) voltage
> signal from a Capella CM3605 ALS into a LUX value.
> 
> Developed and tested with APQ8060 DragonBoard based on
> Ivan's driver. The SPMI VADC driver is quite different,
> but share enough minor functionality that I have split
> out to the common file in a previous patch.
> 
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: Ivan T. Ivanov <[e-mail]>
> Cc: Andy Gross <[e-mail]>
> Cc: Bjorn Andersson <[e-mail]>
> Cc: Stephen Boyd <[e-mail]>
> Cc: Srinivas Kandagatla <[e-mail]>
> Signed-off-by: Linus Walleij <[e-mail]>
> ---
> ChangeLog v1->v2:
> - Introduce a mutex to avoid different clients stepping on each others'
>   toes
> - Add an of_xlate function to be sure to match the right ADC
> - Add all compatible strings, not just PM8058
> ---
>  drivers/iio/adc/Kconfig             |  10 +
>  drivers/iio/adc/Makefile            |   1 +
>  drivers/iio/adc/qcom-pm8xxx-xoadc.c | 786 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 797 insertions(+)
>  create mode 100644 drivers/iio/adc/qcom-pm8xxx-xoadc.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 7edcf3238620..f0b0cbdb9519 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -380,6 +380,16 @@ config PALMAS_GPADC
>  	  is used in smartphones and tablets and supports a 16 channel
>  	  general purpose ADC.
>  
> +config QCOM_PM8XXX_XOADC
> +	tristate "Qualcomm SSBI PM8xxx PMIC XOADCs"
> +	depends on MFD_PM8XXX
> +	help
> +	  ADC driver for the XOADC portions of the Qualcomm PM8xxx PMICs
> +	  using SSBI transport: PM8018, PM8038, PM8058, PM8917, PM8921.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called qcom-pm8xxx-xoadc.
> +
>  config QCOM_SPMI_IADC
>  	tristate "Qualcomm SPMI PMIC current ADC"
>  	depends on SPMI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index f9468d228b1e..234d45c805f9 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -40,6 +40,7 @@ obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
>  obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
>  qcom-vadc-y := qcom-vadc-common.o
>  obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-vadc.o qcom-spmi-vadc.o
> +obj-$(CONFIG_QCOM_PM8XXX_XOADC) += qcom-vadc.o qcom-pm8xxx-xoadc.o
>  obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
>  obj-$(CONFIG_STX104) += stx104.o
>  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> diff --git a/drivers/iio/adc/qcom-pm8xxx-xoadc.c b/drivers/iio/adc/qcom-pm8xxx-xoadc.c
> new file mode 100644
> index 000000000000..32500d5d2989
> --- /dev/null
> +++ b/drivers/iio/adc/qcom-pm8xxx-xoadc.c
> @@ -0,0 +1,786 @@
> +/*
> + * Qualcomm PM8xxx PMIC XOADC driver
> + *
> + * These ADCs are known as HK/XO (house keeping / chrystal oscillator)
> + * "XO" in "XOADC" means Chrystal Oscillator. It's a bunch of

2x crystal

> + * specific-purpose and general purpose ADC converters and channels.
> + *
> + * Copyright (C) 2016 Linaro Ltd.
> + * Author: Linus Walleij <[e-mail]>
> + */
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include "qcom-vadc-common.h"

common prefix for all #define and declarations would be nice

> +
> +/*
> + * Definitions for the "user processor" registers lifted from the v3.4
> + * Qualcomm tree. Their kernel has two out-of-tree drivers for the ADC:
> + * drivers/misc/pmic8058-xoadc.c
> + * drivers/hwmon/pm8xxx-adc.c
> + * None of them contain any complete register specification, so this is
> + * a best effort of combining the information.
> + */
> +
> +/* These appear to be "battery monitor" registers */
> +#define ADC_ARB_BTM_CNTRL1			0x17e
> +#define ADC_ARB_BTM_CNTRL1_EN_BTM		BIT(0)
> +#define ADC_ARB_BTM_CNTRL1_SEL_OP_MODE		BIT(1)
> +#define ADC_ARB_BTM_CNTRL1_MEAS_INTERVAL1	BIT(2)
> +#define ADC_ARB_BTM_CNTRL1_MEAS_INTERVAL2	BIT(3)
> +#define ADC_ARB_BTM_CNTRL1_MEAS_INTERVAL3	BIT(4)
> +#define ADC_ARB_BTM_CNTRL1_MEAS_INTERVAL4	BIT(5)
> +#define ADC_ARB_BTM_CNTRL1_EOC			BIT(6)
> +#define ADC_ARB_BTM_CNTRL1_REQ			BIT(7)
> +
> +#define ADC_ARB_BTM_AMUX_CNTRL			0x17f
> +#define ADC_ARB_BTM_ANA_PARAM			0x180
> +#define ADC_ARB_BTM_DIG_PARAM			0x181
> +#define ADC_ARB_BTM_RSV				0x182
> +#define ADC_ARB_BTM_DATA1			0x183
> +#define ADC_ARB_BTM_DATA0			0x184
> +#define ADC_ARB_BTM_BAT_COOL_THR1		0x185
> +#define ADC_ARB_BTM_BAT_COOL_THR0		0x186
> +#define ADC_ARB_BTM_BAT_WARM_THR1		0x187
> +#define ADC_ARB_BTM_BAT_WARM_THR0		0x188
> +#define ADC_ARB_BTM_CNTRL2			0x18c
> +
> +/* Proper ADC registers */
> +
> +#define ADC_ARB_USRP_CNTRL			0x197
> +#define ADC_ARB_USRP_CNTRL_EN_ARB		BIT(0)
> +#define ADC_ARB_USRP_CNTRL_RSV1			BIT(1)
> +#define ADC_ARB_USRP_CNTRL_RSV2			BIT(2)
> +#define ADC_ARB_USRP_CNTRL_RSV3			BIT(3)
> +#define ADC_ARB_USRP_CNTRL_RSV4			BIT(4)
> +#define ADC_ARB_USRP_CNTRL_RSV5			BIT(5)
> +#define ADC_ARB_USRP_CNTRL_EOC			BIT(6)
> +#define ADC_ARB_USRP_CNTRL_REQ			BIT(7)
> +
> +#define ADC_ARB_USRP_AMUX_CNTRL			0x198
> +#define ADC_ARB_USRP_AMUX_CNTRL_RSV0		BIT(0)
> +#define ADC_ARB_USRP_AMUX_CNTRL_RSV1		BIT(1)
> +#define ADC_ARB_USRP_AMUX_CNTRL_PREMUX0		BIT(2)
> +#define ADC_ARB_USRP_AMUX_CNTRL_PREMUX1		BIT(3)
> +#define ADC_ARB_USRP_AMUX_CNTRL_SEL0		BIT(4)
> +#define ADC_ARB_USRP_AMUX_CNTRL_SEL1		BIT(5)
> +#define ADC_ARB_USRP_AMUX_CNTRL_SEL2		BIT(6)
> +#define ADC_ARB_USRP_AMUX_CNTRL_SEL3		BIT(7)
> +#define ADC_AMUX_PREMUX_SHIFT			2
> +#define ADC_AMUX_SEL_SHIFT			4
> +
> +/* We know very little about the bits in this register */
> +#define ADC_ARB_USRP_ANA_PARAM			0x199
> +#define ADC_ARB_USRP_ANA_PARAM_DIS		0xFE
> +#define ADC_ARB_USRP_ANA_PARAM_EN		0xFF
> +
> +#define ADC_ARB_USRP_DIG_PARAM			0x19A
> +#define ADC_ARB_USRP_DIG_PARAM_SEL_SHIFT0	BIT(0)
> +#define ADC_ARB_USRP_DIG_PARAM_SEL_SHIFT1	BIT(1)
> +#define ADC_ARB_USRP_DIG_PARAM_CLK_RATE0	BIT(2)
> +#define ADC_ARB_USRP_DIG_PARAM_CLK_RATE1	BIT(3)
> +#define ADC_ARB_USRP_DIG_PARAM_EOC		BIT(4)
> +/*
> + * On a later ADC the decimation factors are defined as
> + * 00 = 512, 01 = 1024, 10 = 2048, 11 = 4096 so assume this
> + * holds also for this older XOADC.
> + */
> +#define ADC_ARB_USRP_DIG_PARAM_DEC_RATE0	BIT(5)
> +#define ADC_ARB_USRP_DIG_PARAM_DEC_RATE1	BIT(6)
> +#define ADC_ARB_USRP_DIG_PARAM_EN		BIT(7)
> +#define ADC_DIG_PARAM_DEC_SHIFT			5
> +
> +#define ADC_ARB_USRP_RSV			0x19B
> +#define ADC_ARB_USRP_RSV_RST			BIT(0)
> +#define ADC_ARB_USRP_RSV_DTEST0			BIT(1)
> +#define ADC_ARB_USRP_RSV_DTEST1			BIT(2)
> +#define ADC_ARB_USRP_RSV_OP			BIT(3)
> +#define ADC_ARB_USRP_RSV_IP_SEL0		BIT(4)
> +#define ADC_ARB_USRP_RSV_IP_SEL1		BIT(5)
> +#define ADC_ARB_USRP_RSV_IP_SEL2		BIT(6)
> +#define ADC_ARB_USRP_RSV_TRM			BIT(7)
> +#define ADC_RSV_IP_SEL_SHIFT			4
> +
> +#define ADC_ARB_USRP_DATA0			0x19D
> +#define ADC_ARB_USRP_DATA1			0x19C
> +
> +/* Physical channels. MPP = Multi-Purpose Pin */
> +#define CHANNEL_VCOIN		0x0 /* Coincell */
> +#define CHANNEL_VBAT		0x1 /* Battery voltage */
> +#define CHANNEL_VCHG		0x2 /* Charger voltage */
> +#define CHANNEL_CHG_MONITOR	0x3 /* Charger current monitor */
> +#define CHANNEL_VPH_PWR		0x4 /* Main system power VPH */
> +#define CHANNEL_MPP5		0x5 /* "Battery charge current" */
> +#define CHANNEL_MPP6		0x6 /* "MPP1" */
> +#define CHANNEL_MPP7		0x7 /* "MPP2" */
> +#define CHANNEL_MPP8		0x8 /* Battery temperature */
> +#define CHANNEL_MPP9		0x9 /* Battery detection */
> +#define CHANNEL_USB_VBUS	0xa /* USB charger voltage */
> +#define CHANNEL_DIE_TEMP	0xb /* PMIC die temperature */
> +#define CHANNEL_INTERNAL	0xc /* 625mV reference channel */
> +#define CHANNEL_125V		0xd /* 1.25V reference channel */
> +#define CHANNEL_INTERNAL_2	0xe /* Charger temperature */
> +#define CHANNEL_MUXOFF		0xf /* Channel to reduce input load on mux */
> +
> +#define XOADC_CHAN_MAX		15 /* 4 bits */
> +
> +/* MPP = Multi-Purpose Pins */
> +#define PREMUX_MPP_SCALE_0 0x0 /* No scaling on the signal */
> +#define PREMUX_MPP_SCALE_1 0x1 /* Unity scaling selected by the user */
> +#define PREMUX_MPP_SCALE_1_DIV3 0x2 /* 1/3 prescaler on the input from MPP */
> +
> +/* Defines reference voltage for the XOADC */
> +#define AMUX_RSV0 0x0 /* XO_IN/XOADC_GND */
> +#define AMUX_RSV1 0x1 /* PMIC_IN/XOADC_GND */
> +#define AMUX_RSV2 0x2 /* PMIC_IN/BMS_CSP */
> +#define AMUX_RSV3 0x3 /* not used */
> +#define AMUX_RSV4 0x4 /* XOADC_GND/XOADC_GND */
> +#define AMUX_RSV5 0x5 /* XOADC_VREF/XOADC_GND */
> +#define XOADC_RSV_MAX 5 /* 3 bits 0..7, 3 and 6,7 are invalid */
> +
> +/*
> + * The different channels have hard-coded prescale ratios defined
> + * by the hardware.
> + */
> +static const struct vadc_prescale_ratio adc_prescale_ratios[] = {
> +	{ .num = 1, .den = 2 }, /* CHANNEL_VCOIN */
> +	{ .num = 1, .den = 3 }, /* CHANNEL_VBAT */
> +	{ .num = 1, .den = 10 }, /* CHANNEL_VCHG */
> +	{ .num = 1, .den = 1 }, /* CHANNEL_CHG_MONITOR */
> +	{ .num =  1, .den = 3 }, /* CHANNEL_VPH_PWR */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_MPP5 */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_MPP6 */
> +	{ .num =  1, .den = 2 }, /* CHANNEL_MPP7 */
> +	{ .num =  1, .den = 2 }, /* CHANNEL_MPP8 */
> +	{ .num =  1, .den = 3 }, /* CHANNEL_MPP9 */
> +	{ .num =  1, .den = 3 }, /* CHANNEL_USB_VBUS */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_DIE_TEMP */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_INTERNAL */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_125V */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_INTERNAL_2 */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_MUXOFF */
> +};
> +
> +/**
> + * struct pm8xxx_chan_info - ADC channel information
> + * @name: name of this channel
> + * @calibration: whether to use absolute or ratiometric calibration
> + * @amux_channel: channel 0..15
> + * @decimation: 0,1,2,3
> + * @amux_mpp_channel: MPP channel 0..3
> + * @amux_ip_rsv: ratiometric scale value if using ratiometric
> + * calibration: 0, 1, 2, 4, 5.
> + */
> +struct pm8xxx_chan_info {
> +	const char *name;
> +	enum vadc_calibration calibration;
> +	u8 amux_channel:4;
> +	u8 decimation:2;
> +	u8 amux_mpp_channel:2;
> +	u8 amux_ip_rsv:3;
> +};
> +
> +/**
> + * struct pm8xxx_xoadc - state container for the XOADC
> + * @dev: pointer to device
> + * @map: regmap to access registers
> + * @vref: reference voltage regulator
> + * @nchans: number of channels
> + * @chans: the channel information per-channel
> + * @iio_chans: IIO channel specifiers
> + * @graph: linear calibration parameters for absolute and
> + * ratiometric measurements
> + * @complete: completion to indicate end of conversion
> + * @lock: lock to restrict access to the hardware to one client at the time
> + */
> +struct pm8xxx_xoadc {
> +	struct device *dev;
> +	struct regmap *map;
> +	struct regulator *vref;
> +	unsigned int nchans;
> +	struct pm8xxx_chan_info *chans;
> +	struct iio_chan_spec *iio_chans;
> +	struct vadc_linear_graph graph[2];
> +	struct completion complete;
> +	struct mutex lock;
> +};
> +
> +static irqreturn_t pm8xxx_eoc_irq(int irq, void *d)
> +{
> +	struct iio_dev *indio_dev = d;
> +	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
> +
> +	complete(&adc->complete);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static struct pm8xxx_chan_info *
> +pm8xxx_get_channel(struct pm8xxx_xoadc *adc, u8 chan)
> +{
> +	struct pm8xxx_chan_info *ch;
> +	int i;
> +
> +	for (i = 0; i < adc->nchans; i++) {
> +		ch = &adc->chans[i];
> +		if (ch->amux_channel == chan)
> +			break;

return ch;
directly here

> +	}

just
return NULL;

> +	if (i == adc->nchans)
> +		return NULL;
> +
> +	return ch;
> +}
> +
> +static int pm8xxx_read_channel_rsv(struct pm8xxx_xoadc *adc,
> +				   const struct pm8xxx_chan_info *ch,
> +				   u8 rsv, u16 *adc_code)
> +{
> +	int ret;
> +	unsigned int val;
> +	u8 rsvmask, rsvval;
> +	u8 lsb, msb;
> +
> +	dev_dbg(adc->dev, "read channel \"%s\", amux %d, mpp %d, rsv %d\n",
> +		ch->name, ch->amux_channel, ch->amux_mpp_channel, rsv);
> +
> +	mutex_lock(&adc->lock);
> +
> +	/* Mux in this channel */
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_AMUX_CNTRL,
> +			   ch->amux_channel << ADC_AMUX_SEL_SHIFT |
> +			   ch->amux_mpp_channel << ADC_AMUX_PREMUX_SHIFT);
> +	if (ret)
> +		goto unlock;
> +
> +	/* Set up ratiometric scale value */
> +	rsvmask = (ADC_ARB_USRP_RSV_RST | ADC_ARB_USRP_RSV_DTEST0 |
> +		   ADC_ARB_USRP_RSV_DTEST1 | ADC_ARB_USRP_RSV_OP);
> +	if (ch->calibration == VADC_CALIB_RATIOMETRIC) {
> +		if (rsv == 0xff)
> +			rsvval = (ch->amux_ip_rsv << ADC_RSV_IP_SEL_SHIFT) |
> +				ADC_ARB_USRP_RSV_TRM;
> +		else
> +			rsvval = (rsv << ADC_RSV_IP_SEL_SHIFT) |
> +				ADC_ARB_USRP_RSV_TRM;
> +	} else {
> +		/* We are not ratiometric so turn this off */
> +		rsvval = ADC_ARB_USRP_RSV_IP_SEL1;
> +	}
> +
> +	ret = regmap_update_bits(adc->map,
> +				 ADC_ARB_USRP_RSV,
> +				 ~rsvmask,
> +				 rsvval);
> +	if (ret)
> +		goto unlock;
> +
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_ANA_PARAM,
> +			   ADC_ARB_USRP_ANA_PARAM_DIS);
> +	if (ret)
> +		goto unlock;
> +
> +	/* Decimation factor */
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_DIG_PARAM,
> +			   ADC_ARB_USRP_DIG_PARAM_SEL_SHIFT0 |
> +			   ADC_ARB_USRP_DIG_PARAM_SEL_SHIFT1 |
> +			   ch->decimation << ADC_DIG_PARAM_DEC_SHIFT);
> +	if (ret)
> +		goto unlock;
> +
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_ANA_PARAM,
> +			   ADC_ARB_USRP_ANA_PARAM_EN);
> +	if (ret)
> +		goto unlock;
> +
> +	/* Enable the arbiter, the Qualcomm code does it twice like this */
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL,
> +			   ADC_ARB_USRP_CNTRL_EN_ARB);
> +	if (ret)
> +		goto unlock;
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL,
> +			   ADC_ARB_USRP_CNTRL_EN_ARB);
> +	if (ret)
> +		goto unlock;
> +
> +
> +	/* Fire a request! */
> +	reinit_completion(&adc->complete);
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL,
> +			   ADC_ARB_USRP_CNTRL_EN_ARB |
> +			   ADC_ARB_USRP_CNTRL_REQ);
> +	if (ret)
> +		goto unlock;
> +
> +	/* Next the interrupt occurs */
> +	ret = wait_for_completion_timeout(&adc->complete,
> +					  VADC_CONV_TIME_MAX_US);
> +	if (!ret) {
> +		dev_err(adc->dev, "conversion timed out\n");
> +		ret = -ETIMEDOUT;
> +		goto unlock;
> +	}
> +
> +	ret = regmap_read(adc->map, ADC_ARB_USRP_DATA0, &val);
> +	if (ret)
> +		goto unlock;
> +	lsb = val;
> +	ret = regmap_read(adc->map, ADC_ARB_USRP_DATA1, &val);
> +	if (ret)
> +		goto unlock;
> +	msb = val;
> +	*adc_code = (msb << 8) | lsb;
> +
> +	/* Turn off the ADC by setting the arbiter to 0 twice */
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL, 0);
> +	if (ret)
> +		goto unlock;
> +	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL, 0);
> +	if (ret)
> +		goto unlock;
> +
> +unlock:
> +	mutex_unlock(&adc->lock);
> +	return ret;
> +}
> +
> +static int pm8xxx_read_channel(struct pm8xxx_xoadc *adc,
> +			       const struct pm8xxx_chan_info *ch,
> +			       u16 *adc_code)
> +{
> +	/*
> +	 * Normally we just use the ratiometric scale value (RSV) predefined
> +	 * for the channel, but during calibration we need to modify this
> +	 * so this wrapper is a helper hiding the more complex version.
> +	 */
> +	return pm8xxx_read_channel_rsv(adc, ch, 0xff, adc_code);
> +}
> +
> +static s32 pm8xxx_calibrate(struct pm8xxx_xoadc *adc,
> +			    const struct pm8xxx_chan_info *ch,
> +			    u16 adc_code)
> +{
> +	return qcom_vadc_calibrate(&adc_prescale_ratios[ch->amux_channel],
> +				   &adc->graph[ch->calibration],
> +				   (ch->calibration == VADC_CALIB_ABSOLUTE),
> +				   adc_code);
> +}
> +
> +static int pm8xxx_calibrate_device(struct pm8xxx_xoadc *adc)
> +{
> +	const struct pm8xxx_chan_info *ch;
> +	u16 read_1250v;
> +	u16 read_0625v;
> +	u16 read_nomux_rsv5;
> +	u16 read_nomux_rsv4;
> +	int ret;
> +
> +
> +	adc->graph[VADC_CALIB_ABSOLUTE].dx = VADC_ABSOLUTE_RANGE_UV;
> +	adc->graph[VADC_CALIB_RATIOMETRIC].dx = VADC_RATIOMETRIC_RANGE_UV;
> +
> +	/* Common reference channel calibration */
> +	ch = pm8xxx_get_channel(adc, CHANNEL_125V);
> +	if (!ch)
> +		return -ENODEV;
> +	ret = pm8xxx_read_channel(adc, ch, &read_1250v);
> +	if (ret) {
> +		dev_err(adc->dev, "could not read 1.25V reference channel\n");
> +		return -ENODEV;
> +	}
> +	ch = pm8xxx_get_channel(adc, CHANNEL_INTERNAL);
> +	if (!ch)
> +		return -ENODEV;
> +	ret = pm8xxx_read_channel(adc, ch, &read_0625v);
> +	if (ret) {
> +		dev_err(adc->dev, "could not read 0.625V reference channel\n");
> +		return -ENODEV;
> +	}
> +	if (read_1250v == read_0625v) {
> +		dev_err(adc->dev, "read same ADC code for 1.25V and 0.625V\n");
> +		return -ENODEV;
> +	}
> +
> +	adc->graph[VADC_CALIB_ABSOLUTE].dy = read_1250v - read_0625v;
> +	adc->graph[VADC_CALIB_ABSOLUTE].gnd = read_0625v;
> +
> +	dev_info(adc->dev, "absolute calibration dx = %d uV, dy = %d units\n",
> +		 VADC_ABSOLUTE_RANGE_UV, adc->graph[VADC_CALIB_ABSOLUTE].dy);
> +
> +	/* Ratiometric calibration */
> +	ch = pm8xxx_get_channel(adc, CHANNEL_MUXOFF);
> +	if (!ch)
> +		return -ENODEV;
> +	ret = pm8xxx_read_channel_rsv(adc, ch, AMUX_RSV5, &read_nomux_rsv5);
> +	if (ret) {
> +		dev_err(adc->dev, "could not read MUXOFF reference channel\n");
> +		return -ENODEV;
> +	}
> +	ret = pm8xxx_read_channel_rsv(adc, ch, AMUX_RSV4, &read_nomux_rsv4);
> +	if (ret) {
> +		dev_err(adc->dev, "could not read MUXOFF reference channel\n");
> +		return -ENODEV;
> +	}
> +	adc->graph[VADC_CALIB_RATIOMETRIC].dy =
> +		read_nomux_rsv5 - read_nomux_rsv4;
> +	adc->graph[VADC_CALIB_RATIOMETRIC].gnd = read_nomux_rsv4;
> +
> +	dev_info(adc->dev, "ratiometric calibration dx = %d uV, dy = %d units\n",
> +		 VADC_RATIOMETRIC_RANGE_UV,
> +		 adc->graph[VADC_CALIB_RATIOMETRIC].dy);
> +
> +	return 0;
> +}
> +
> +static int pm8xxx_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
> +	const struct pm8xxx_chan_info *ch;
> +	u16 adc_code;
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		/* Only die temperature ends up here */
> +		ch = pm8xxx_get_channel(adc, chan->address);
> +		if (!ch) {
> +			dev_err(adc->dev, "no such channel %lu\n",
> +				chan->address);
> +			return -EINVAL;
> +		}
> +		ret = pm8xxx_read_channel(adc, ch, &adc_code);
> +		if (ret)
> +			return ret;
> +		*val = pm8xxx_calibrate(adc, ch, adc_code);
> +		/* 2mV/K, return milli Celsius */
> +		*val /= 2;
> +		*val -= KELVINMIL_CELSIUSMIL;
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_VOLTAGE:


any global state involved here?
locking might be needed

> +			ch = pm8xxx_get_channel(adc, chan->address);
> +			if (!ch) {
> +				dev_err(adc->dev, "no such channel %lu\n",
> +					chan->address);
> +				return -EINVAL;
> +			}
> +			ret = pm8xxx_read_channel(adc, ch, &adc_code);
> +			if (ret)
> +				return ret;
> +			*val = pm8xxx_calibrate(adc, ch, adc_code);
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_SCALE:
> +		/*
> +		 * Applies to all voltage channels: we scale the microvolts
> +		 * to millivolts as required by the userspace ABI.
> +		 */
> +		*val = 0;
> +		*val2 = 1000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int pm8xxx_of_xlate(struct iio_dev *indio_dev,
> +			   const struct of_phandle_args *iiospec)
> +{
> +	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
> +	unsigned int i;
> +
> +	for (i = 0; i < adc->nchans; i++)
> +		if (adc->iio_chans[i].channel == iiospec->args[0])
> +			return i;
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info pm8xxx_xoadc_info = {
> +	.driver_module = THIS_MODULE,
> +	.of_xlate = pm8xxx_of_xlate,
> +	.read_raw = pm8xxx_read_raw,
> +};
> +
> +static int pm8xxx_xoadc_parse_channel(struct device *dev,
> +				      struct device_node *np,
> +				      struct pm8xxx_chan_info *ch)
> +{
> +	const char *name = np->name;
> +	u32 chan, rsv, dec;
> +	int ret;
> +
> +	ret = of_property_read_u32(np, "reg", &chan);
> +	if (ret) {
> +		dev_err(dev, "invalid channel number %s\n", name);
> +		return ret;
> +	}
> +	if (chan > XOADC_CHAN_MAX) {
> +		dev_err(dev, "%s too big channel number %d\n", name, chan);
> +		return -EINVAL;
> +	}
> +
> +	if (of_property_read_bool(np, "qcom,ratiometric")) {
> +		ch->calibration = VADC_CALIB_RATIOMETRIC;
> +		ret = of_property_read_u32(np, "qcom,ratiometric-ref", &rsv);
> +		if (ret) {
> +			dev_err(dev, "invalid RSV %s\n", name);
> +			return ret;
> +		}
> +		if (rsv > XOADC_RSV_MAX) {
> +			dev_err(dev, "%s too large RSV value %d\n", name, rsv);
> +			return -EINVAL;
> +		}
> +		if (rsv == AMUX_RSV3) {
> +			dev_err(dev, "%s invalid RSV value %d\n", name, rsv);
> +			return -EINVAL;
> +		}
> +	} else {
> +		ch->calibration = VADC_CALIB_ABSOLUTE;
> +		rsv = 0;
> +	}
> +
> +	ret = of_property_read_u32(np, "qcom,decimation", &dec);
> +	if (!ret) {
> +		/* It's OK to skip this ... */
> +		ret = qcom_vadc_decimation_from_dt(dec);
> +		if (ret < 0) {
> +			dev_err(dev, "%s invalid decimation %d\n",
> +				name, dec);
> +			return ret;
> +		}
> +		ch->decimation = ret;
> +	} else {
> +		ch->decimation = VADC_DEF_DECIMATION;
> +	}
> +
> +	ch->amux_channel = chan;
> +	ch->name = name;
> +	ch->amux_ip_rsv = rsv;
> +	ch->amux_mpp_channel = PREMUX_MPP_SCALE_0; /* FIXME: get from DT */
> +
> +	dev_dbg(dev, "channel %d \"%s\" ref voltage: %d, decimation %d\n",
> +		ch->amux_channel,
> +		ch->name,
> +		ch->amux_ip_rsv,
> +		ch->decimation);
> +	return 0;
> +}
> +
> +static int pm8xxx_xoadc_parse_channels(struct pm8xxx_xoadc *adc,
> +				       struct device_node *np)
> +{
> +	struct device_node *child;
> +	struct pm8xxx_chan_info *ch;
> +	int ret;
> +	int i;
> +
> +	adc->nchans = of_get_available_child_count(np);
> +	if (!adc->nchans) {
> +		dev_err(adc->dev, "no channel children\n");
> +		return -ENODEV;
> +	}
> +	dev_dbg(adc->dev, "found %d ADC channels\n", adc->nchans);
> +
> +	adc->iio_chans = devm_kcalloc(adc->dev, adc->nchans,
> +				      sizeof(*adc->iio_chans), GFP_KERNEL);
> +	if (!adc->iio_chans)
> +		return -ENOMEM;
> +
> +	adc->chans = devm_kcalloc(adc->dev, adc->nchans,
> +				  sizeof(*adc->chans), GFP_KERNEL);
> +	if (!adc->chans)
> +		return -ENOMEM;
> +
> +	i = 0;
> +	for_each_available_child_of_node(np, child) {
> +		struct iio_chan_spec *iio_chan;
> +
> +		ch = &adc->chans[i];
> +		ret = pm8xxx_xoadc_parse_channel(adc->dev, child, ch);
> +		if (ret) {
> +			of_node_put(child);
> +			return ret;
> +		}
> +
> +		iio_chan = &adc->iio_chans[i];
> +		iio_chan->channel = ch->amux_channel;
> +		iio_chan->datasheet_name = ch->name;
> +		/* A single temperature channel, the rest are voltages */
> +		if (ch->amux_channel == CHANNEL_DIE_TEMP) {
> +			iio_chan->type = IIO_TEMP;
> +			iio_chan->info_mask_separate =
> +				BIT(IIO_CHAN_INFO_PROCESSED);
> +		} else {
> +			iio_chan->type = IIO_VOLTAGE;
> +			iio_chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				BIT(IIO_CHAN_INFO_SCALE);
> +		}
> +		iio_chan->indexed = 1;
> +		iio_chan->address = ch->amux_channel;
> +
> +		i++;
> +	}
> +
> +	/* Check for required channels */
> +	ch = pm8xxx_get_channel(adc, CHANNEL_125V);
> +	if (!ch) {
> +		dev_err(adc->dev, "missing 1.25V reference channel\n");
> +		return -ENODEV;
> +	}
> +	ch = pm8xxx_get_channel(adc, CHANNEL_INTERNAL);
> +	if (!ch) {
> +		dev_err(adc->dev, "missing 0.625V reference channel\n");
> +		return -ENODEV;
> +	}
> +	ch = pm8xxx_get_channel(adc, CHANNEL_MUXOFF);
> +	if (!ch) {
> +		dev_err(adc->dev, "missing MUXOFF reference channel\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int pm8xxx_xoadc_probe(struct platform_device *pdev)
> +{
> +	struct pm8xxx_xoadc *adc;
> +	struct iio_dev *indio_dev;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct regmap *map;
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	adc = iio_priv(indio_dev);
> +	adc->dev = dev;
> +	init_completion(&adc->complete);
> +	mutex_init(&adc->lock);
> +
> +	ret = pm8xxx_xoadc_parse_channels(adc, np);
> +	if (ret)
> +		return ret;
> +
> +	map = dev_get_regmap(dev->parent, NULL);
> +	if (!map) {
> +		dev_err(dev, "Parent regmap unavailable.\n");

most other strings start lowercase :)

> +		return -ENXIO;
> +	}
> +	adc->map = map;
> +
> +	/* Bring up regulator */
> +	adc->vref = devm_regulator_get(dev, "xoadc-ref");
> +	if (IS_ERR(adc->vref)) {
> +		dev_err(dev, "failed to get XOADC VREF regulator\n");
> +		return PTR_ERR(adc->vref);
> +	}
> +	/* We strictly require this voltage */
> +	ret = regulator_set_voltage(adc->vref, 2200000, 2200000);
> +	if (ret) {
> +		dev_err(dev, "unable to set LDO18 voltage to 2.2V\n");
> +		return ret;
> +	}
> +	ret = regulator_enable(adc->vref);
> +	if (ret) {
> +		dev_err(dev, "failed to enable XOADC VREF regulator\n");
> +		return ret;
> +	}
> +
> +	ret = devm_request_threaded_irq(dev, platform_get_irq(pdev, 0),
> +			pm8xxx_eoc_irq, NULL, 0, "pm8xxx-adc", indio_dev);
> +	if (ret) {
> +		dev_err(dev, "unable to request IRQ\n");
> +		goto out_disable_vref;
> +	}
> +
> +	indio_dev->dev.parent = dev;
> +	indio_dev->dev.of_node = np;
> +	indio_dev->name = "pm8xxx-xoadc";
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &pm8xxx_xoadc_info;
> +	indio_dev->channels = adc->iio_chans;
> +	indio_dev->num_channels = adc->nchans;
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret)
> +		goto out_disable_vref;
> +
> +	ret = pm8xxx_calibrate_device(adc);

shouldn't this be done before the device is registered?

> +	if (ret)
> +		goto out_unreg_device;
> +
> +	dev_info(dev, "PM8xxx XOADC driver enabled\n");

message necessary?

> +
> +	return 0;
> +
> +out_unreg_device:
> +	iio_device_unregister(indio_dev);
> +out_disable_vref:
> +	regulator_disable(adc->vref);
> +
> +	return ret;
> +}
> +
> +static int pm8xxx_xoadc_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	regulator_disable(adc->vref);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id pm8xxx_xoadc_id_table[] = {
> +	{
> +		.compatible = "qcom,pm8018-adc",
> +	},
> +	{
> +		.compatible = "qcom,pm8038-adc",
> +	},
> +	{
> +		.compatible = "qcom,pm8058-adc",
> +	},
> +	{
> +		.compatible = "qcom,pm8917-adc",
> +	},
> +	{
> +		.compatible = "qcom,pm8921-adc",
> +	},
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, pm8xxx_xoadc_id_table);
> +
> +static struct platform_driver pm8xxx_xoadc_driver = {
> +	.driver		= {
> +		.name	= "pm8xxx-adc",
> +		.of_match_table = pm8xxx_xoadc_id_table,
> +	},
> +	.probe		= pm8xxx_xoadc_probe,
> +	.remove		= pm8xxx_xoadc_remove,
> +};
> +module_platform_driver(pm8xxx_xoadc_driver);
> +
> +MODULE_DESCRIPTION("PM8xxx XOADC driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:pm8xxx-xoadc");
>

Bjorn Andersson Dec. 27, 2016, 6:58 a.m. UTC | #2

On Thu 15 Dec 14:48 PST 2016, Linus Walleij wrote:

> The Qualcomm PM8xxx PMICs contain a simpler ADC than its
> successors (already in the kernel as qcom-spmi-adc.c):
> the HK/XO ADC (Housekeeping/Chrystal oscillator ADC).
> 
> As far as I can understand this is equal to the PMICs
> using SSBI transport and encompass PM8018, PM8038,
> PM8058, PM8917 and PM8921, so this is shortly named
> PM8xxx.
> 
> This ADC monitors a bunch of on-board voltages and the die
> temperature of the PMIC itself, but it can also be routed
> to convert a few external MPPs (multi-purpose pins). On
> the APQ8060 DragonBoard this feature is used to let this
> ADC convert an analog ALS (Ambient Light Sensor) voltage
> signal from a Capella CM3605 ALS into a LUX value.
> 
> Developed and tested with APQ8060 DragonBoard based on
> Ivan's driver. The SPMI VADC driver is quite different,
> but share enough minor functionality that I have split
> out to the common file in a previous patch.

I gave this a spin on one of my APQ8064 devices - with PM8921 - and I
can do measurements.

Several of the channels do give me reasonable readings. But the channels
in PM8921 are different than PM8058, so it looks like we need additional
prescales defined. Further more, the 8921 has several different
thermo-related channels, each with their own (post-)scaling function.

And lastly it seems that I have 2 thermo-channels on "mpp amux", but I'm
still confused to how that is supposed to work in the downstream code -
I will need to investigate this further.


One of the channels defined in my APQ8064 device measures
ADC_MPP_1_AMUX5, a lookup table is used to convert the measured value to
a temperature. As the table depends on an external thermistor, which
seems to differ between products a number of lookup tables exists - with
156 data points each.

[..]
> +
> +/*
> + * The different channels have hard-coded prescale ratios defined
> + * by the hardware.
> + */
> +static const struct vadc_prescale_ratio adc_prescale_ratios[] = {
> +	{ .num = 1, .den = 2 }, /* CHANNEL_VCOIN */
> +	{ .num = 1, .den = 3 }, /* CHANNEL_VBAT */
> +	{ .num = 1, .den = 10 }, /* CHANNEL_VCHG */
> +	{ .num = 1, .den = 1 }, /* CHANNEL_CHG_MONITOR */
> +	{ .num =  1, .den = 3 }, /* CHANNEL_VPH_PWR */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_MPP5 */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_MPP6 */
> +	{ .num =  1, .den = 2 }, /* CHANNEL_MPP7 */
> +	{ .num =  1, .den = 2 }, /* CHANNEL_MPP8 */
> +	{ .num =  1, .den = 3 }, /* CHANNEL_MPP9 */
> +	{ .num =  1, .den = 3 }, /* CHANNEL_USB_VBUS */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_DIE_TEMP */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_INTERNAL */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_125V */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_INTERNAL_2 */
> +	{ .num =  1, .den = 1 }, /* CHANNEL_MUXOFF */
> +};

The pm8921 have different meaning for the channels and the prescale
values are hence different. In the downstream kernel the values comes
from the board file, but I don't know if that means they will ever
change.

[..]
> +
> +static int pm8xxx_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
> +	const struct pm8xxx_chan_info *ch;
> +	u16 adc_code;
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		/* Only die temperature ends up here */
> +		ch = pm8xxx_get_channel(adc, chan->address);
> +		if (!ch) {
> +			dev_err(adc->dev, "no such channel %lu\n",
> +				chan->address);
> +			return -EINVAL;
> +		}
> +		ret = pm8xxx_read_channel(adc, ch, &adc_code);
> +		if (ret)
> +			return ret;
> +		*val = pm8xxx_calibrate(adc, ch, adc_code);
> +		/* 2mV/K, return milli Celsius */
> +		*val /= 2;
> +		*val -= KELVINMIL_CELSIUSMIL;

On my 8064 device I have 6 different temperatures (2 coming from amux'ed
mpp channels). They all have different lookup tables, which seems
calibrated based on some external resistor.

> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_RAW:
> +		switch (chan->type) {
> +		case IIO_VOLTAGE:
> +			ch = pm8xxx_get_channel(adc, chan->address);
> +			if (!ch) {
> +				dev_err(adc->dev, "no such channel %lu\n",
> +					chan->address);
> +				return -EINVAL;
> +			}
> +			ret = pm8xxx_read_channel(adc, ch, &adc_code);
> +			if (ret)
> +				return ret;
> +			*val = pm8xxx_calibrate(adc, ch, adc_code);
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	case IIO_CHAN_INFO_SCALE:
> +		/*
> +		 * Applies to all voltage channels: we scale the microvolts
> +		 * to millivolts as required by the userspace ABI.
> +		 */
> +		*val = 0;
> +		*val2 = 1000;
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int pm8xxx_of_xlate(struct iio_dev *indio_dev,
> +			   const struct of_phandle_args *iiospec)
> +{
> +	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
> +	unsigned int i;
> +
> +	for (i = 0; i < adc->nchans; i++)
> +		if (adc->iio_chans[i].channel == iiospec->args[0])
> +			return i;
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info pm8xxx_xoadc_info = {
> +	.driver_module = THIS_MODULE,
> +	.of_xlate = pm8xxx_of_xlate,
> +	.read_raw = pm8xxx_read_raw,
> +};
> +
> +static int pm8xxx_xoadc_parse_channel(struct device *dev,
> +				      struct device_node *np,
> +				      struct pm8xxx_chan_info *ch)
> +{
> +	const char *name = np->name;
> +	u32 chan, rsv, dec;
> +	int ret;
> +
> +	ret = of_property_read_u32(np, "reg", &chan);
> +	if (ret) {
> +		dev_err(dev, "invalid channel number %s\n", name);
> +		return ret;
> +	}
> +	if (chan > XOADC_CHAN_MAX) {
> +		dev_err(dev, "%s too big channel number %d\n", name, chan);
> +		return -EINVAL;
> +	}
> +
> +	if (of_property_read_bool(np, "qcom,ratiometric")) {
> +		ch->calibration = VADC_CALIB_RATIOMETRIC;
> +		ret = of_property_read_u32(np, "qcom,ratiometric-ref", &rsv);

If this is what you intended, you can squash the two properties into
one.

> +		if (ret) {
> +			dev_err(dev, "invalid RSV %s\n", name);
> +			return ret;
> +		}
> +		if (rsv > XOADC_RSV_MAX) {
> +			dev_err(dev, "%s too large RSV value %d\n", name, rsv);
> +			return -EINVAL;
> +		}
> +		if (rsv == AMUX_RSV3) {
> +			dev_err(dev, "%s invalid RSV value %d\n", name, rsv);
> +			return -EINVAL;
> +		}
> +	} else {
> +		ch->calibration = VADC_CALIB_ABSOLUTE;
> +		rsv = 0;
> +	}
> +
> +	ret = of_property_read_u32(np, "qcom,decimation", &dec);
> +	if (!ret) {
> +		/* It's OK to skip this ... */
> +		ret = qcom_vadc_decimation_from_dt(dec);
> +		if (ret < 0) {
> +			dev_err(dev, "%s invalid decimation %d\n",
> +				name, dec);
> +			return ret;
> +		}
> +		ch->decimation = ret;
> +	} else {
> +		ch->decimation = VADC_DEF_DECIMATION;
> +	}
> +
> +	ch->amux_channel = chan;
> +	ch->name = name;
> +	ch->amux_ip_rsv = rsv;
> +	ch->amux_mpp_channel = PREMUX_MPP_SCALE_0; /* FIXME: get from DT */

After reading the code related to "amux/mpp" I've quite confused, it
does indeed look like the only thing done is to apply some scaling to
the value - but this doesn't make sense looking at the board files and
naming of the defines used downstream.

I will have to try to find some hints in the documentation and play
around with this a little bit more.

> +
> +	dev_dbg(dev, "channel %d \"%s\" ref voltage: %d, decimation %d\n",
> +		ch->amux_channel,
> +		ch->name,
> +		ch->amux_ip_rsv,
> +		ch->decimation);
> +	return 0;
> +}
> +
> +static int pm8xxx_xoadc_parse_channels(struct pm8xxx_xoadc *adc,
> +				       struct device_node *np)
> +{
> +	struct device_node *child;
> +	struct pm8xxx_chan_info *ch;
> +	int ret;
> +	int i;
> +
> +	adc->nchans = of_get_available_child_count(np);
> +	if (!adc->nchans) {
> +		dev_err(adc->dev, "no channel children\n");
> +		return -ENODEV;
> +	}
> +	dev_dbg(adc->dev, "found %d ADC channels\n", adc->nchans);
> +
> +	adc->iio_chans = devm_kcalloc(adc->dev, adc->nchans,
> +				      sizeof(*adc->iio_chans), GFP_KERNEL);
> +	if (!adc->iio_chans)
> +		return -ENOMEM;
> +
> +	adc->chans = devm_kcalloc(adc->dev, adc->nchans,
> +				  sizeof(*adc->chans), GFP_KERNEL);
> +	if (!adc->chans)
> +		return -ENOMEM;
> +
> +	i = 0;
> +	for_each_available_child_of_node(np, child) {
> +		struct iio_chan_spec *iio_chan;
> +
> +		ch = &adc->chans[i];
> +		ret = pm8xxx_xoadc_parse_channel(adc->dev, child, ch);
> +		if (ret) {
> +			of_node_put(child);
> +			return ret;
> +		}
> +
> +		iio_chan = &adc->iio_chans[i];
> +		iio_chan->channel = ch->amux_channel;
> +		iio_chan->datasheet_name = ch->name;
> +		/* A single temperature channel, the rest are voltages */
> +		if (ch->amux_channel == CHANNEL_DIE_TEMP) {
> +			iio_chan->type = IIO_TEMP;
> +			iio_chan->info_mask_separate =
> +				BIT(IIO_CHAN_INFO_PROCESSED);
> +		} else {
> +			iio_chan->type = IIO_VOLTAGE;
> +			iio_chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				BIT(IIO_CHAN_INFO_SCALE);
> +		}
> +		iio_chan->indexed = 1;
> +		iio_chan->address = ch->amux_channel;
> +
> +		i++;
> +	}
> +
> +	/* Check for required channels */
> +	ch = pm8xxx_get_channel(adc, CHANNEL_125V);
> +	if (!ch) {
> +		dev_err(adc->dev, "missing 1.25V reference channel\n");
> +		return -ENODEV;
> +	}
> +	ch = pm8xxx_get_channel(adc, CHANNEL_INTERNAL);
> +	if (!ch) {
> +		dev_err(adc->dev, "missing 0.625V reference channel\n");
> +		return -ENODEV;
> +	}
> +	ch = pm8xxx_get_channel(adc, CHANNEL_MUXOFF);
> +	if (!ch) {
> +		dev_err(adc->dev, "missing MUXOFF reference channel\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int pm8xxx_xoadc_probe(struct platform_device *pdev)
> +{
> +	struct pm8xxx_xoadc *adc;
> +	struct iio_dev *indio_dev;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct regmap *map;
> +	struct device *dev = &pdev->dev;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	adc = iio_priv(indio_dev);
> +	adc->dev = dev;
> +	init_completion(&adc->complete);
> +	mutex_init(&adc->lock);
> +
> +	ret = pm8xxx_xoadc_parse_channels(adc, np);
> +	if (ret)
> +		return ret;
> +
> +	map = dev_get_regmap(dev->parent, NULL);
> +	if (!map) {
> +		dev_err(dev, "Parent regmap unavailable.\n");
> +		return -ENXIO;
> +	}
> +	adc->map = map;
> +
> +	/* Bring up regulator */
> +	adc->vref = devm_regulator_get(dev, "xoadc-ref");
> +	if (IS_ERR(adc->vref)) {
> +		dev_err(dev, "failed to get XOADC VREF regulator\n");
> +		return PTR_ERR(adc->vref);
> +	}
> +	/* We strictly require this voltage */
> +	ret = regulator_set_voltage(adc->vref, 2200000, 2200000);

On 8064 the reference is L14 and it's at 1.8V, so this fails for me.

However, the way that this is written should reflect on the board design
and your L18 (and my L14) will have a single valid value. As such  there
should be no need to set a voltage here (other then to catch mistakes).

> +	if (ret) {
> +		dev_err(dev, "unable to set LDO18 voltage to 2.2V\n");
> +		return ret;
> +	}

Regards,
Bjorn
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Linus Walleij Jan. 17, 2017, 2:35 p.m. UTC | #3

On Tue, Dec 27, 2016 at 7:58 AM, Bjorn Andersson
<[e-mail]> wrote:
> On Thu 15 Dec 14:48 PST 2016, Linus Walleij wrote:

> I gave this a spin on one of my APQ8064 devices - with PM8921 - and I
> can do measurements.

Nice :) I hope the v3 patchset also gives something, hopefully more.

> Several of the channels do give me reasonable readings. But the channels
> in PM8921 are different than PM8058, so it looks like we need additional
> prescales defined. Further more, the 8921 has several different
> thermo-related channels, each with their own (post-)scaling function.

I hope I have fixed this for all variants in the v3 version.

> And lastly it seems that I have 2 thermo-channels on "mpp amux", but I'm
> still confused to how that is supposed to work in the downstream code -
> I will need to investigate this further.
>
> One of the channels defined in my APQ8064 device measures
> ADC_MPP_1_AMUX5, a lookup table is used to convert the measured value to
> a temperature. As the table depends on an external thermistor, which
> seems to differ between products a number of lookup tables exists - with
> 156 data points each.
(...)
> On my 8064 device I have 6 different temperatures (2 coming from amux'ed
> mpp channels). They all have different lookup tables, which seems
> calibrated based on some external resistor.

Rama Krishna cleared it up a bit, then I have tried to make it even
clearer.

Essentially all MPP (multi-purpose pins indeed) can have any random
analog value coming in, but there are some layers of enums on top
of the actual hardware channels confusing things a bit.

Some MPPs are used for reading battery temperature and system
temperature in some systems, but this is essentially a board-specific
use of a general purpose ADC and need to be above the driver, however
I tried to encode the most typical usecases a bit in the different PMIC
channel tables, so that MPP8 is usually set up a temperature channel.

We need additional bindings to specify conversion functions from the
device tree but that can be made on top of this patch set as an
expansion.

The approach chosen here is that this ADC driver should present
"processed" (scaled etc) values, and to achieve this the scaling is
done directly on the raw values read from the ADC, which are
first scaled to uV from calibration and then scaled to e.g. a
temperature.

This is all clearer after Rama Krishna's patches.

>> +     /* We strictly require this voltage */
>> +     ret = regulator_set_voltage(adc->vref, 2200000, 2200000);
>
> On 8064 the reference is L14 and it's at 1.8V, so this fails for me.

I have removes this hard setting of voltage.

Yours,
Linus Walleij
--
To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 7edcf3238620..f0b0cbdb9519 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -380,6 +380,16 @@  config PALMAS_GPADC
 	  is used in smartphones and tablets and supports a 16 channel
 	  general purpose ADC.
 
+config QCOM_PM8XXX_XOADC
+	tristate "Qualcomm SSBI PM8xxx PMIC XOADCs"
+	depends on MFD_PM8XXX
+	help
+	  ADC driver for the XOADC portions of the Qualcomm PM8xxx PMICs
+	  using SSBI transport: PM8018, PM8038, PM8058, PM8917, PM8921.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called qcom-pm8xxx-xoadc.
+
 config QCOM_SPMI_IADC
 	tristate "Qualcomm SPMI PMIC current ADC"
 	depends on SPMI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index f9468d228b1e..234d45c805f9 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -40,6 +40,7 @@  obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
 obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
 qcom-vadc-y := qcom-vadc-common.o
 obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-vadc.o qcom-spmi-vadc.o
+obj-$(CONFIG_QCOM_PM8XXX_XOADC) += qcom-vadc.o qcom-pm8xxx-xoadc.o
 obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
 obj-$(CONFIG_STX104) += stx104.o
 obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
diff --git a/drivers/iio/adc/qcom-pm8xxx-xoadc.c b/drivers/iio/adc/qcom-pm8xxx-xoadc.c
new file mode 100644
index 000000000000..32500d5d2989
--- /dev/null
+++ b/drivers/iio/adc/qcom-pm8xxx-xoadc.c
@@ -0,0 +1,786 @@ 
+/*
+ * Qualcomm PM8xxx PMIC XOADC driver
+ *
+ * These ADCs are known as HK/XO (house keeping / chrystal oscillator)
+ * "XO" in "XOADC" means Chrystal Oscillator. It's a bunch of
+ * specific-purpose and general purpose ADC converters and channels.
+ *
+ * Copyright (C) 2016 Linaro Ltd.
+ * Author: Linus Walleij <[e-mail]>
+ */
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/regulator/consumer.h>
+
+#include "qcom-vadc-common.h"
+
+/*
+ * Definitions for the "user processor" registers lifted from the v3.4
+ * Qualcomm tree. Their kernel has two out-of-tree drivers for the ADC:
+ * drivers/misc/pmic8058-xoadc.c
+ * drivers/hwmon/pm8xxx-adc.c
+ * None of them contain any complete register specification, so this is
+ * a best effort of combining the information.
+ */
+
+/* These appear to be "battery monitor" registers */
+#define ADC_ARB_BTM_CNTRL1			0x17e
+#define ADC_ARB_BTM_CNTRL1_EN_BTM		BIT(0)
+#define ADC_ARB_BTM_CNTRL1_SEL_OP_MODE		BIT(1)
+#define ADC_ARB_BTM_CNTRL1_MEAS_INTERVAL1	BIT(2)
+#define ADC_ARB_BTM_CNTRL1_MEAS_INTERVAL2	BIT(3)
+#define ADC_ARB_BTM_CNTRL1_MEAS_INTERVAL3	BIT(4)
+#define ADC_ARB_BTM_CNTRL1_MEAS_INTERVAL4	BIT(5)
+#define ADC_ARB_BTM_CNTRL1_EOC			BIT(6)
+#define ADC_ARB_BTM_CNTRL1_REQ			BIT(7)
+
+#define ADC_ARB_BTM_AMUX_CNTRL			0x17f
+#define ADC_ARB_BTM_ANA_PARAM			0x180
+#define ADC_ARB_BTM_DIG_PARAM			0x181
+#define ADC_ARB_BTM_RSV				0x182
+#define ADC_ARB_BTM_DATA1			0x183
+#define ADC_ARB_BTM_DATA0			0x184
+#define ADC_ARB_BTM_BAT_COOL_THR1		0x185
+#define ADC_ARB_BTM_BAT_COOL_THR0		0x186
+#define ADC_ARB_BTM_BAT_WARM_THR1		0x187
+#define ADC_ARB_BTM_BAT_WARM_THR0		0x188
+#define ADC_ARB_BTM_CNTRL2			0x18c
+
+/* Proper ADC registers */
+
+#define ADC_ARB_USRP_CNTRL			0x197
+#define ADC_ARB_USRP_CNTRL_EN_ARB		BIT(0)
+#define ADC_ARB_USRP_CNTRL_RSV1			BIT(1)
+#define ADC_ARB_USRP_CNTRL_RSV2			BIT(2)
+#define ADC_ARB_USRP_CNTRL_RSV3			BIT(3)
+#define ADC_ARB_USRP_CNTRL_RSV4			BIT(4)
+#define ADC_ARB_USRP_CNTRL_RSV5			BIT(5)
+#define ADC_ARB_USRP_CNTRL_EOC			BIT(6)
+#define ADC_ARB_USRP_CNTRL_REQ			BIT(7)
+
+#define ADC_ARB_USRP_AMUX_CNTRL			0x198
+#define ADC_ARB_USRP_AMUX_CNTRL_RSV0		BIT(0)
+#define ADC_ARB_USRP_AMUX_CNTRL_RSV1		BIT(1)
+#define ADC_ARB_USRP_AMUX_CNTRL_PREMUX0		BIT(2)
+#define ADC_ARB_USRP_AMUX_CNTRL_PREMUX1		BIT(3)
+#define ADC_ARB_USRP_AMUX_CNTRL_SEL0		BIT(4)
+#define ADC_ARB_USRP_AMUX_CNTRL_SEL1		BIT(5)
+#define ADC_ARB_USRP_AMUX_CNTRL_SEL2		BIT(6)
+#define ADC_ARB_USRP_AMUX_CNTRL_SEL3		BIT(7)
+#define ADC_AMUX_PREMUX_SHIFT			2
+#define ADC_AMUX_SEL_SHIFT			4
+
+/* We know very little about the bits in this register */
+#define ADC_ARB_USRP_ANA_PARAM			0x199
+#define ADC_ARB_USRP_ANA_PARAM_DIS		0xFE
+#define ADC_ARB_USRP_ANA_PARAM_EN		0xFF
+
+#define ADC_ARB_USRP_DIG_PARAM			0x19A
+#define ADC_ARB_USRP_DIG_PARAM_SEL_SHIFT0	BIT(0)
+#define ADC_ARB_USRP_DIG_PARAM_SEL_SHIFT1	BIT(1)
+#define ADC_ARB_USRP_DIG_PARAM_CLK_RATE0	BIT(2)
+#define ADC_ARB_USRP_DIG_PARAM_CLK_RATE1	BIT(3)
+#define ADC_ARB_USRP_DIG_PARAM_EOC		BIT(4)
+/*
+ * On a later ADC the decimation factors are defined as
+ * 00 = 512, 01 = 1024, 10 = 2048, 11 = 4096 so assume this
+ * holds also for this older XOADC.
+ */
+#define ADC_ARB_USRP_DIG_PARAM_DEC_RATE0	BIT(5)
+#define ADC_ARB_USRP_DIG_PARAM_DEC_RATE1	BIT(6)
+#define ADC_ARB_USRP_DIG_PARAM_EN		BIT(7)
+#define ADC_DIG_PARAM_DEC_SHIFT			5
+
+#define ADC_ARB_USRP_RSV			0x19B
+#define ADC_ARB_USRP_RSV_RST			BIT(0)
+#define ADC_ARB_USRP_RSV_DTEST0			BIT(1)
+#define ADC_ARB_USRP_RSV_DTEST1			BIT(2)
+#define ADC_ARB_USRP_RSV_OP			BIT(3)
+#define ADC_ARB_USRP_RSV_IP_SEL0		BIT(4)
+#define ADC_ARB_USRP_RSV_IP_SEL1		BIT(5)
+#define ADC_ARB_USRP_RSV_IP_SEL2		BIT(6)
+#define ADC_ARB_USRP_RSV_TRM			BIT(7)
+#define ADC_RSV_IP_SEL_SHIFT			4
+
+#define ADC_ARB_USRP_DATA0			0x19D
+#define ADC_ARB_USRP_DATA1			0x19C
+
+/* Physical channels. MPP = Multi-Purpose Pin */
+#define CHANNEL_VCOIN		0x0 /* Coincell */
+#define CHANNEL_VBAT		0x1 /* Battery voltage */
+#define CHANNEL_VCHG		0x2 /* Charger voltage */
+#define CHANNEL_CHG_MONITOR	0x3 /* Charger current monitor */
+#define CHANNEL_VPH_PWR		0x4 /* Main system power VPH */
+#define CHANNEL_MPP5		0x5 /* "Battery charge current" */
+#define CHANNEL_MPP6		0x6 /* "MPP1" */
+#define CHANNEL_MPP7		0x7 /* "MPP2" */
+#define CHANNEL_MPP8		0x8 /* Battery temperature */
+#define CHANNEL_MPP9		0x9 /* Battery detection */
+#define CHANNEL_USB_VBUS	0xa /* USB charger voltage */
+#define CHANNEL_DIE_TEMP	0xb /* PMIC die temperature */
+#define CHANNEL_INTERNAL	0xc /* 625mV reference channel */
+#define CHANNEL_125V		0xd /* 1.25V reference channel */
+#define CHANNEL_INTERNAL_2	0xe /* Charger temperature */
+#define CHANNEL_MUXOFF		0xf /* Channel to reduce input load on mux */
+
+#define XOADC_CHAN_MAX		15 /* 4 bits */
+
+/* MPP = Multi-Purpose Pins */
+#define PREMUX_MPP_SCALE_0 0x0 /* No scaling on the signal */
+#define PREMUX_MPP_SCALE_1 0x1 /* Unity scaling selected by the user */
+#define PREMUX_MPP_SCALE_1_DIV3 0x2 /* 1/3 prescaler on the input from MPP */
+
+/* Defines reference voltage for the XOADC */
+#define AMUX_RSV0 0x0 /* XO_IN/XOADC_GND */
+#define AMUX_RSV1 0x1 /* PMIC_IN/XOADC_GND */
+#define AMUX_RSV2 0x2 /* PMIC_IN/BMS_CSP */
+#define AMUX_RSV3 0x3 /* not used */
+#define AMUX_RSV4 0x4 /* XOADC_GND/XOADC_GND */
+#define AMUX_RSV5 0x5 /* XOADC_VREF/XOADC_GND */
+#define XOADC_RSV_MAX 5 /* 3 bits 0..7, 3 and 6,7 are invalid */
+
+/*
+ * The different channels have hard-coded prescale ratios defined
+ * by the hardware.
+ */
+static const struct vadc_prescale_ratio adc_prescale_ratios[] = {
+	{ .num = 1, .den = 2 }, /* CHANNEL_VCOIN */
+	{ .num = 1, .den = 3 }, /* CHANNEL_VBAT */
+	{ .num = 1, .den = 10 }, /* CHANNEL_VCHG */
+	{ .num = 1, .den = 1 }, /* CHANNEL_CHG_MONITOR */
+	{ .num =  1, .den = 3 }, /* CHANNEL_VPH_PWR */
+	{ .num =  1, .den = 1 }, /* CHANNEL_MPP5 */
+	{ .num =  1, .den = 1 }, /* CHANNEL_MPP6 */
+	{ .num =  1, .den = 2 }, /* CHANNEL_MPP7 */
+	{ .num =  1, .den = 2 }, /* CHANNEL_MPP8 */
+	{ .num =  1, .den = 3 }, /* CHANNEL_MPP9 */
+	{ .num =  1, .den = 3 }, /* CHANNEL_USB_VBUS */
+	{ .num =  1, .den = 1 }, /* CHANNEL_DIE_TEMP */
+	{ .num =  1, .den = 1 }, /* CHANNEL_INTERNAL */
+	{ .num =  1, .den = 1 }, /* CHANNEL_125V */
+	{ .num =  1, .den = 1 }, /* CHANNEL_INTERNAL_2 */
+	{ .num =  1, .den = 1 }, /* CHANNEL_MUXOFF */
+};
+
+/**
+ * struct pm8xxx_chan_info - ADC channel information
+ * @name: name of this channel
+ * @calibration: whether to use absolute or ratiometric calibration
+ * @amux_channel: channel 0..15
+ * @decimation: 0,1,2,3
+ * @amux_mpp_channel: MPP channel 0..3
+ * @amux_ip_rsv: ratiometric scale value if using ratiometric
+ * calibration: 0, 1, 2, 4, 5.
+ */
+struct pm8xxx_chan_info {
+	const char *name;
+	enum vadc_calibration calibration;
+	u8 amux_channel:4;
+	u8 decimation:2;
+	u8 amux_mpp_channel:2;
+	u8 amux_ip_rsv:3;
+};
+
+/**
+ * struct pm8xxx_xoadc - state container for the XOADC
+ * @dev: pointer to device
+ * @map: regmap to access registers
+ * @vref: reference voltage regulator
+ * @nchans: number of channels
+ * @chans: the channel information per-channel
+ * @iio_chans: IIO channel specifiers
+ * @graph: linear calibration parameters for absolute and
+ * ratiometric measurements
+ * @complete: completion to indicate end of conversion
+ * @lock: lock to restrict access to the hardware to one client at the time
+ */
+struct pm8xxx_xoadc {
+	struct device *dev;
+	struct regmap *map;
+	struct regulator *vref;
+	unsigned int nchans;
+	struct pm8xxx_chan_info *chans;
+	struct iio_chan_spec *iio_chans;
+	struct vadc_linear_graph graph[2];
+	struct completion complete;
+	struct mutex lock;
+};
+
+static irqreturn_t pm8xxx_eoc_irq(int irq, void *d)
+{
+	struct iio_dev *indio_dev = d;
+	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
+
+	complete(&adc->complete);
+
+	return IRQ_HANDLED;
+}
+
+static struct pm8xxx_chan_info *
+pm8xxx_get_channel(struct pm8xxx_xoadc *adc, u8 chan)
+{
+	struct pm8xxx_chan_info *ch;
+	int i;
+
+	for (i = 0; i < adc->nchans; i++) {
+		ch = &adc->chans[i];
+		if (ch->amux_channel == chan)
+			break;
+	}
+	if (i == adc->nchans)
+		return NULL;
+
+	return ch;
+}
+
+static int pm8xxx_read_channel_rsv(struct pm8xxx_xoadc *adc,
+				   const struct pm8xxx_chan_info *ch,
+				   u8 rsv, u16 *adc_code)
+{
+	int ret;
+	unsigned int val;
+	u8 rsvmask, rsvval;
+	u8 lsb, msb;
+
+	dev_dbg(adc->dev, "read channel \"%s\", amux %d, mpp %d, rsv %d\n",
+		ch->name, ch->amux_channel, ch->amux_mpp_channel, rsv);
+
+	mutex_lock(&adc->lock);
+
+	/* Mux in this channel */
+	ret = regmap_write(adc->map, ADC_ARB_USRP_AMUX_CNTRL,
+			   ch->amux_channel << ADC_AMUX_SEL_SHIFT |
+			   ch->amux_mpp_channel << ADC_AMUX_PREMUX_SHIFT);
+	if (ret)
+		goto unlock;
+
+	/* Set up ratiometric scale value */
+	rsvmask = (ADC_ARB_USRP_RSV_RST | ADC_ARB_USRP_RSV_DTEST0 |
+		   ADC_ARB_USRP_RSV_DTEST1 | ADC_ARB_USRP_RSV_OP);
+	if (ch->calibration == VADC_CALIB_RATIOMETRIC) {
+		if (rsv == 0xff)
+			rsvval = (ch->amux_ip_rsv << ADC_RSV_IP_SEL_SHIFT) |
+				ADC_ARB_USRP_RSV_TRM;
+		else
+			rsvval = (rsv << ADC_RSV_IP_SEL_SHIFT) |
+				ADC_ARB_USRP_RSV_TRM;
+	} else {
+		/* We are not ratiometric so turn this off */
+		rsvval = ADC_ARB_USRP_RSV_IP_SEL1;
+	}
+
+	ret = regmap_update_bits(adc->map,
+				 ADC_ARB_USRP_RSV,
+				 ~rsvmask,
+				 rsvval);
+	if (ret)
+		goto unlock;
+
+	ret = regmap_write(adc->map, ADC_ARB_USRP_ANA_PARAM,
+			   ADC_ARB_USRP_ANA_PARAM_DIS);
+	if (ret)
+		goto unlock;
+
+	/* Decimation factor */
+	ret = regmap_write(adc->map, ADC_ARB_USRP_DIG_PARAM,
+			   ADC_ARB_USRP_DIG_PARAM_SEL_SHIFT0 |
+			   ADC_ARB_USRP_DIG_PARAM_SEL_SHIFT1 |
+			   ch->decimation << ADC_DIG_PARAM_DEC_SHIFT);
+	if (ret)
+		goto unlock;
+
+	ret = regmap_write(adc->map, ADC_ARB_USRP_ANA_PARAM,
+			   ADC_ARB_USRP_ANA_PARAM_EN);
+	if (ret)
+		goto unlock;
+
+	/* Enable the arbiter, the Qualcomm code does it twice like this */
+	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL,
+			   ADC_ARB_USRP_CNTRL_EN_ARB);
+	if (ret)
+		goto unlock;
+	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL,
+			   ADC_ARB_USRP_CNTRL_EN_ARB);
+	if (ret)
+		goto unlock;
+
+
+	/* Fire a request! */
+	reinit_completion(&adc->complete);
+	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL,
+			   ADC_ARB_USRP_CNTRL_EN_ARB |
+			   ADC_ARB_USRP_CNTRL_REQ);
+	if (ret)
+		goto unlock;
+
+	/* Next the interrupt occurs */
+	ret = wait_for_completion_timeout(&adc->complete,
+					  VADC_CONV_TIME_MAX_US);
+	if (!ret) {
+		dev_err(adc->dev, "conversion timed out\n");
+		ret = -ETIMEDOUT;
+		goto unlock;
+	}
+
+	ret = regmap_read(adc->map, ADC_ARB_USRP_DATA0, &val);
+	if (ret)
+		goto unlock;
+	lsb = val;
+	ret = regmap_read(adc->map, ADC_ARB_USRP_DATA1, &val);
+	if (ret)
+		goto unlock;
+	msb = val;
+	*adc_code = (msb << 8) | lsb;
+
+	/* Turn off the ADC by setting the arbiter to 0 twice */
+	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL, 0);
+	if (ret)
+		goto unlock;
+	ret = regmap_write(adc->map, ADC_ARB_USRP_CNTRL, 0);
+	if (ret)
+		goto unlock;
+
+unlock:
+	mutex_unlock(&adc->lock);
+	return ret;
+}
+
+static int pm8xxx_read_channel(struct pm8xxx_xoadc *adc,
+			       const struct pm8xxx_chan_info *ch,
+			       u16 *adc_code)
+{
+	/*
+	 * Normally we just use the ratiometric scale value (RSV) predefined
+	 * for the channel, but during calibration we need to modify this
+	 * so this wrapper is a helper hiding the more complex version.
+	 */
+	return pm8xxx_read_channel_rsv(adc, ch, 0xff, adc_code);
+}
+
+static s32 pm8xxx_calibrate(struct pm8xxx_xoadc *adc,
+			    const struct pm8xxx_chan_info *ch,
+			    u16 adc_code)
+{
+	return qcom_vadc_calibrate(&adc_prescale_ratios[ch->amux_channel],
+				   &adc->graph[ch->calibration],
+				   (ch->calibration == VADC_CALIB_ABSOLUTE),
+				   adc_code);
+}
+
+static int pm8xxx_calibrate_device(struct pm8xxx_xoadc *adc)
+{
+	const struct pm8xxx_chan_info *ch;
+	u16 read_1250v;
+	u16 read_0625v;
+	u16 read_nomux_rsv5;
+	u16 read_nomux_rsv4;
+	int ret;
+
+
+	adc->graph[VADC_CALIB_ABSOLUTE].dx = VADC_ABSOLUTE_RANGE_UV;
+	adc->graph[VADC_CALIB_RATIOMETRIC].dx = VADC_RATIOMETRIC_RANGE_UV;
+
+	/* Common reference channel calibration */
+	ch = pm8xxx_get_channel(adc, CHANNEL_125V);
+	if (!ch)
+		return -ENODEV;
+	ret = pm8xxx_read_channel(adc, ch, &read_1250v);
+	if (ret) {
+		dev_err(adc->dev, "could not read 1.25V reference channel\n");
+		return -ENODEV;
+	}
+	ch = pm8xxx_get_channel(adc, CHANNEL_INTERNAL);
+	if (!ch)
+		return -ENODEV;
+	ret = pm8xxx_read_channel(adc, ch, &read_0625v);
+	if (ret) {
+		dev_err(adc->dev, "could not read 0.625V reference channel\n");
+		return -ENODEV;
+	}
+	if (read_1250v == read_0625v) {
+		dev_err(adc->dev, "read same ADC code for 1.25V and 0.625V\n");
+		return -ENODEV;
+	}
+
+	adc->graph[VADC_CALIB_ABSOLUTE].dy = read_1250v - read_0625v;
+	adc->graph[VADC_CALIB_ABSOLUTE].gnd = read_0625v;
+
+	dev_info(adc->dev, "absolute calibration dx = %d uV, dy = %d units\n",
+		 VADC_ABSOLUTE_RANGE_UV, adc->graph[VADC_CALIB_ABSOLUTE].dy);
+
+	/* Ratiometric calibration */
+	ch = pm8xxx_get_channel(adc, CHANNEL_MUXOFF);
+	if (!ch)
+		return -ENODEV;
+	ret = pm8xxx_read_channel_rsv(adc, ch, AMUX_RSV5, &read_nomux_rsv5);
+	if (ret) {
+		dev_err(adc->dev, "could not read MUXOFF reference channel\n");
+		return -ENODEV;
+	}
+	ret = pm8xxx_read_channel_rsv(adc, ch, AMUX_RSV4, &read_nomux_rsv4);
+	if (ret) {
+		dev_err(adc->dev, "could not read MUXOFF reference channel\n");
+		return -ENODEV;
+	}
+	adc->graph[VADC_CALIB_RATIOMETRIC].dy =
+		read_nomux_rsv5 - read_nomux_rsv4;
+	adc->graph[VADC_CALIB_RATIOMETRIC].gnd = read_nomux_rsv4;
+
+	dev_info(adc->dev, "ratiometric calibration dx = %d uV, dy = %d units\n",
+		 VADC_RATIOMETRIC_RANGE_UV,
+		 adc->graph[VADC_CALIB_RATIOMETRIC].dy);
+
+	return 0;
+}
+
+static int pm8xxx_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
+	const struct pm8xxx_chan_info *ch;
+	u16 adc_code;
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		/* Only die temperature ends up here */
+		ch = pm8xxx_get_channel(adc, chan->address);
+		if (!ch) {
+			dev_err(adc->dev, "no such channel %lu\n",
+				chan->address);
+			return -EINVAL;
+		}
+		ret = pm8xxx_read_channel(adc, ch, &adc_code);
+		if (ret)
+			return ret;
+		*val = pm8xxx_calibrate(adc, ch, adc_code);
+		/* 2mV/K, return milli Celsius */
+		*val /= 2;
+		*val -= KELVINMIL_CELSIUSMIL;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			ch = pm8xxx_get_channel(adc, chan->address);
+			if (!ch) {
+				dev_err(adc->dev, "no such channel %lu\n",
+					chan->address);
+				return -EINVAL;
+			}
+			ret = pm8xxx_read_channel(adc, ch, &adc_code);
+			if (ret)
+				return ret;
+			*val = pm8xxx_calibrate(adc, ch, adc_code);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * Applies to all voltage channels: we scale the microvolts
+		 * to millivolts as required by the userspace ABI.
+		 */
+		*val = 0;
+		*val2 = 1000;
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int pm8xxx_of_xlate(struct iio_dev *indio_dev,
+			   const struct of_phandle_args *iiospec)
+{
+	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
+	unsigned int i;
+
+	for (i = 0; i < adc->nchans; i++)
+		if (adc->iio_chans[i].channel == iiospec->args[0])
+			return i;
+
+	return -EINVAL;
+}
+
+static const struct iio_info pm8xxx_xoadc_info = {
+	.driver_module = THIS_MODULE,
+	.of_xlate = pm8xxx_of_xlate,
+	.read_raw = pm8xxx_read_raw,
+};
+
+static int pm8xxx_xoadc_parse_channel(struct device *dev,
+				      struct device_node *np,
+				      struct pm8xxx_chan_info *ch)
+{
+	const char *name = np->name;
+	u32 chan, rsv, dec;
+	int ret;
+
+	ret = of_property_read_u32(np, "reg", &chan);
+	if (ret) {
+		dev_err(dev, "invalid channel number %s\n", name);
+		return ret;
+	}
+	if (chan > XOADC_CHAN_MAX) {
+		dev_err(dev, "%s too big channel number %d\n", name, chan);
+		return -EINVAL;
+	}
+
+	if (of_property_read_bool(np, "qcom,ratiometric")) {
+		ch->calibration = VADC_CALIB_RATIOMETRIC;
+		ret = of_property_read_u32(np, "qcom,ratiometric-ref", &rsv);
+		if (ret) {
+			dev_err(dev, "invalid RSV %s\n", name);
+			return ret;
+		}
+		if (rsv > XOADC_RSV_MAX) {
+			dev_err(dev, "%s too large RSV value %d\n", name, rsv);
+			return -EINVAL;
+		}
+		if (rsv == AMUX_RSV3) {
+			dev_err(dev, "%s invalid RSV value %d\n", name, rsv);
+			return -EINVAL;
+		}
+	} else {
+		ch->calibration = VADC_CALIB_ABSOLUTE;
+		rsv = 0;
+	}
+
+	ret = of_property_read_u32(np, "qcom,decimation", &dec);
+	if (!ret) {
+		/* It's OK to skip this ... */
+		ret = qcom_vadc_decimation_from_dt(dec);
+		if (ret < 0) {
+			dev_err(dev, "%s invalid decimation %d\n",
+				name, dec);
+			return ret;
+		}
+		ch->decimation = ret;
+	} else {
+		ch->decimation = VADC_DEF_DECIMATION;
+	}
+
+	ch->amux_channel = chan;
+	ch->name = name;
+	ch->amux_ip_rsv = rsv;
+	ch->amux_mpp_channel = PREMUX_MPP_SCALE_0; /* FIXME: get from DT */
+
+	dev_dbg(dev, "channel %d \"%s\" ref voltage: %d, decimation %d\n",
+		ch->amux_channel,
+		ch->name,
+		ch->amux_ip_rsv,
+		ch->decimation);
+	return 0;
+}
+
+static int pm8xxx_xoadc_parse_channels(struct pm8xxx_xoadc *adc,
+				       struct device_node *np)
+{
+	struct device_node *child;
+	struct pm8xxx_chan_info *ch;
+	int ret;
+	int i;
+
+	adc->nchans = of_get_available_child_count(np);
+	if (!adc->nchans) {
+		dev_err(adc->dev, "no channel children\n");
+		return -ENODEV;
+	}
+	dev_dbg(adc->dev, "found %d ADC channels\n", adc->nchans);
+
+	adc->iio_chans = devm_kcalloc(adc->dev, adc->nchans,
+				      sizeof(*adc->iio_chans), GFP_KERNEL);
+	if (!adc->iio_chans)
+		return -ENOMEM;
+
+	adc->chans = devm_kcalloc(adc->dev, adc->nchans,
+				  sizeof(*adc->chans), GFP_KERNEL);
+	if (!adc->chans)
+		return -ENOMEM;
+
+	i = 0;
+	for_each_available_child_of_node(np, child) {
+		struct iio_chan_spec *iio_chan;
+
+		ch = &adc->chans[i];
+		ret = pm8xxx_xoadc_parse_channel(adc->dev, child, ch);
+		if (ret) {
+			of_node_put(child);
+			return ret;
+		}
+
+		iio_chan = &adc->iio_chans[i];
+		iio_chan->channel = ch->amux_channel;
+		iio_chan->datasheet_name = ch->name;
+		/* A single temperature channel, the rest are voltages */
+		if (ch->amux_channel == CHANNEL_DIE_TEMP) {
+			iio_chan->type = IIO_TEMP;
+			iio_chan->info_mask_separate =
+				BIT(IIO_CHAN_INFO_PROCESSED);
+		} else {
+			iio_chan->type = IIO_VOLTAGE;
+			iio_chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				BIT(IIO_CHAN_INFO_SCALE);
+		}
+		iio_chan->indexed = 1;
+		iio_chan->address = ch->amux_channel;
+
+		i++;
+	}
+
+	/* Check for required channels */
+	ch = pm8xxx_get_channel(adc, CHANNEL_125V);
+	if (!ch) {
+		dev_err(adc->dev, "missing 1.25V reference channel\n");
+		return -ENODEV;
+	}
+	ch = pm8xxx_get_channel(adc, CHANNEL_INTERNAL);
+	if (!ch) {
+		dev_err(adc->dev, "missing 0.625V reference channel\n");
+		return -ENODEV;
+	}
+	ch = pm8xxx_get_channel(adc, CHANNEL_MUXOFF);
+	if (!ch) {
+		dev_err(adc->dev, "missing MUXOFF reference channel\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static int pm8xxx_xoadc_probe(struct platform_device *pdev)
+{
+	struct pm8xxx_xoadc *adc;
+	struct iio_dev *indio_dev;
+	struct device_node *np = pdev->dev.of_node;
+	struct regmap *map;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
+	if (!indio_dev)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, indio_dev);
+
+	adc = iio_priv(indio_dev);
+	adc->dev = dev;
+	init_completion(&adc->complete);
+	mutex_init(&adc->lock);
+
+	ret = pm8xxx_xoadc_parse_channels(adc, np);
+	if (ret)
+		return ret;
+
+	map = dev_get_regmap(dev->parent, NULL);
+	if (!map) {
+		dev_err(dev, "Parent regmap unavailable.\n");
+		return -ENXIO;
+	}
+	adc->map = map;
+
+	/* Bring up regulator */
+	adc->vref = devm_regulator_get(dev, "xoadc-ref");
+	if (IS_ERR(adc->vref)) {
+		dev_err(dev, "failed to get XOADC VREF regulator\n");
+		return PTR_ERR(adc->vref);
+	}
+	/* We strictly require this voltage */
+	ret = regulator_set_voltage(adc->vref, 2200000, 2200000);
+	if (ret) {
+		dev_err(dev, "unable to set LDO18 voltage to 2.2V\n");
+		return ret;
+	}
+	ret = regulator_enable(adc->vref);
+	if (ret) {
+		dev_err(dev, "failed to enable XOADC VREF regulator\n");
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(dev, platform_get_irq(pdev, 0),
+			pm8xxx_eoc_irq, NULL, 0, "pm8xxx-adc", indio_dev);
+	if (ret) {
+		dev_err(dev, "unable to request IRQ\n");
+		goto out_disable_vref;
+	}
+
+	indio_dev->dev.parent = dev;
+	indio_dev->dev.of_node = np;
+	indio_dev->name = "pm8xxx-xoadc";
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &pm8xxx_xoadc_info;
+	indio_dev->channels = adc->iio_chans;
+	indio_dev->num_channels = adc->nchans;
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto out_disable_vref;
+
+	ret = pm8xxx_calibrate_device(adc);
+	if (ret)
+		goto out_unreg_device;
+
+	dev_info(dev, "PM8xxx XOADC driver enabled\n");
+
+	return 0;
+
+out_unreg_device:
+	iio_device_unregister(indio_dev);
+out_disable_vref:
+	regulator_disable(adc->vref);
+
+	return ret;
+}
+
+static int pm8xxx_xoadc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct pm8xxx_xoadc *adc = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	regulator_disable(adc->vref);
+
+	return 0;
+}
+
+static const struct of_device_id pm8xxx_xoadc_id_table[] = {
+	{
+		.compatible = "qcom,pm8018-adc",
+	},
+	{
+		.compatible = "qcom,pm8038-adc",
+	},
+	{
+		.compatible = "qcom,pm8058-adc",
+	},
+	{
+		.compatible = "qcom,pm8917-adc",
+	},
+	{
+		.compatible = "qcom,pm8921-adc",
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, pm8xxx_xoadc_id_table);
+
+static struct platform_driver pm8xxx_xoadc_driver = {
+	.driver		= {
+		.name	= "pm8xxx-adc",
+		.of_match_table = pm8xxx_xoadc_id_table,
+	},
+	.probe		= pm8xxx_xoadc_probe,
+	.remove		= pm8xxx_xoadc_remove,
+};
+module_platform_driver(pm8xxx_xoadc_driver);
+
+MODULE_DESCRIPTION("PM8xxx XOADC driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:pm8xxx-xoadc");