iio: adc: cpcap: Add minimal support for CPCAP PMIC ADC

On Motorola phones like droid 4 there is a custom CPCAP PMIC. This PMIC
has ADCs that are used for battery charging and USB PHY VBUS and ID pin
detection.

Unfortunately the only documentation for this ADC seems to be the
Motorola mapphone Linux kernel tree. I have tested that reading raw and
scaled values works, but I have not used the timed sampling that the ADC
seems to support.

Let's add a minimal support for it so we can eventually provide IIO
channels for the related battery charging and USB PHY drivers.

Cc: devicetree@vger.kernel.org
Cc: Marcel Partap <mpartap@gmx.net>
Cc: Michael Scott <michael.scott@linaro.org>
Cc: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Tony Lindgrne <tony@atomide.com>
---
 .../devicetree/bindings/iio/adc/cpcap-adc.txt      |  16 +
 drivers/iio/adc/Kconfig                            |  11 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/cpcap-adc.c                        | 997 +++++++++++++++++++++
 4 files changed, 1025 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt
 create mode 100644 drivers/iio/adc/cpcap-adc.c

> On Motorola phones like droid 4 there is a custom CPCAP PMIC. This PMIC
> has ADCs that are used for battery charging and USB PHY VBUS and ID pin
> detection.
> 
> Unfortunately the only documentation for this ADC seems to be the
> Motorola mapphone Linux kernel tree. I have tested that reading raw and
> scaled values works, but I have not used the timed sampling that the ADC
> seems to support.

comments below
 
> Let's add a minimal support for it so we can eventually provide IIO
> channels for the related battery charging and USB PHY drivers.
> 
> Cc: devicetree@vger.kernel.org
> Cc: Marcel Partap <mpartap@gmx.net>
> Cc: Michael Scott <michael.scott@linaro.org>
> Cc: Sebastian Reichel <sre@kernel.org>
> Signed-off-by: Tony Lindgrne <tony@atomide.com>

Lindgren

> ---
>  .../devicetree/bindings/iio/adc/cpcap-adc.txt      |  16 +
>  drivers/iio/adc/Kconfig                            |  11 +
>  drivers/iio/adc/Makefile                           |   1 +
>  drivers/iio/adc/cpcap-adc.c                        | 997 +++++++++++++++++++++
>  4 files changed, 1025 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt
>  create mode 100644 drivers/iio/adc/cpcap-adc.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt b/Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt
> new file mode 100644
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt
> @@ -0,0 +1,16 @@
> +Motorola CPCAP PMIC ADC binding
> +
> +Required properties:
> +- compatible: Should be "motorola,cpcap-adc" or "motorola,mapphone-cpcap-adc"
> +- interrupts: The interrupt number for the ADC device
> +- interrupt-names: Should be "adcdone"
> +- #io-channel-cells: Number of cells in an IIO specifier
> +
> +Example:
> +
> +cpcap_adc: adc {
> +	compatible = "motorola,mapphone-cpcap-adc";
> +	interrupts-extended = <&cpcap 8 0>;

interrupts?

> +	interrupt-names = "adcdone";
> +	#io-channel-cells = <1>;
> +};
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -195,6 +195,17 @@ config CC10001_ADC
>  	  This driver can also be built as a module. If so, the module will be
>  	  called cc10001_adc.
>  
> +config CPCAP_ADC
> +	tristate "Motorola CPCAP PMIC ADC driver"
> +	depends on MFD_CPCAP
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Say yes here to build support for Motorola CPCAP PMIC ADC.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called cpcap-adc.
> +
>  config DA9150_GPADC
>  	tristate "Dialog DA9150 GPADC driver support"
>  	depends on MFD_DA9150
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -20,6 +20,7 @@ obj-$(CONFIG_AXP288_ADC) += axp288_adc.o
>  obj-$(CONFIG_BCM_IPROC_ADC) += bcm_iproc_adc.o
>  obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
>  obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
> +obj-$(CONFIG_CPCAP_ADC) += cpcap-adc.o
>  obj-$(CONFIG_DA9150_GPADC) += da9150-gpadc.o
>  obj-$(CONFIG_ENVELOPE_DETECTOR) += envelope-detector.o
>  obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
> diff --git a/drivers/iio/adc/cpcap-adc.c b/drivers/iio/adc/cpcap-adc.c
> new file mode 100644
> --- /dev/null
> +++ b/drivers/iio/adc/cpcap-adc.c
> @@ -0,0 +1,997 @@
> +/*
> + * Copyright (C) 2017 Tony Lindgren <tony@atomide.com>
> + *
> + * Rewritten for Linux IIO framework with register managing functions
> + * based on earlier driver found in the Motorola Linux kernel:
> + *
> + * Copyright (C) 2009-2010 Motorola, Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/driver.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/kfifo_buf.h>
> +#include <linux/mfd/motorola-cpcap.h>
> +
> +/* Register CPCAP_REG_ADCC1 bits */
> +#define CPCAP_BIT_ADEN_AUTO_CLR		BIT(15)	/* Currently unused */
> +#define CPCAP_BIT_CAL_MODE		BIT(14) /* Set with BIT_RAND0 */
> +#define CPCAP_BIT_ADC_CLK_SEL1		BIT(13)	/* Currently unused */
> +#define CPCAP_BIT_ADC_CLK_SEL0		BIT(12)	/* Currently unused */
> +#define CPCAP_BIT_ATOX			BIT(11)	/* in/out ps factor */

wondering what a 'ps' factor is...

> +#define CPCAP_BIT_ATO3			BIT(10)
> +#define CPCAP_BIT_ATO2			BIT(9)
> +#define CPCAP_BIT_ATO1			BIT(8)
> +#define CPCAP_BIT_ATO0			BIT(7)
> +#define CPCAP_BIT_ADA2			BIT(6)
> +#define CPCAP_BIT_ADA1			BIT(5)
> +#define CPCAP_BIT_ADA0			BIT(4)
> +#define CPCAP_BIT_AD_SEL1		BIT(3)	/* Set for ADC_TYPE_BANK_1 */
> +#define CPCAP_BIT_RAND1			BIT(2)	/* Set for ADC_TYPE_BATT_PI */
> +#define CPCAP_BIT_RAND0			BIT(1)	/* Set with CAL_MODE */
> +#define CPCAP_BIT_ADEN			BIT(0)	/* Currently unused */
> +
> +/* Register CPCAP_REG_ADCC2 bits */
> +#define CPCAP_BIT_CAL_FACTOR_ENABLE	BIT(15)	/* Currently unused */
> +#define CPCAP_BIT_BATDETB_EN		BIT(14)	/* Currently unused */
> +#define CPCAP_BIT_ADTRIG_ONESHOT	BIT(13)	/* Set for !TIMING_IMM */
> +#define CPCAP_BIT_ASC			BIT(12)	/* Set for TIMING_IMM */
> +#define CPCAP_BIT_ATOX_PS_FACTOR	BIT(11)	/* in/out ps factor */
> +#define CPCAP_BIT_ADC_PS_FACTOR1	BIT(10)	/* in/out ps factor */
> +#define CPCAP_BIT_ADC_PS_FACTOR0	BIT(9)	/* in/out ps factor */
> +#define CPCAP_BIT_AD4_SELECT		BIT(8)	/* Currently unused */
> +#define CPCAP_BIT_ADC_BUSY		BIT(7)	/* Currently unused */
> +#define CPCAP_BIT_THERMBIAS_EN		BIT(6)	/* Currently unused */
> +#define CPCAP_BIT_ADTRIG_DIS		BIT(5)	/* Disable interrupt */
> +#define CPCAP_BIT_LIADC			BIT(4)	/* Currently unused */
> +#define CPCAP_BIT_TS_REFEN		BIT(3)	/* Currently unused */
> +#define CPCAP_BIT_TS_M2			BIT(2)	/* Currently unused */
> +#define CPCAP_BIT_TS_M1			BIT(1)	/* Currently unused */
> +#define CPCAP_BIT_TS_M0			BIT(0)	/* Currently unused */
> +
> +#define MAX_TEMP_LVL			27

generally, we want the CPAP_ prefix

> +#define FOUR_POINT_TWO_ADC		801
> +#define ST_ADC_CAL_CHRGI_UPPER_THRESHOLD 530
> +#define ST_ADC_CAL_CHRGI_LOWER_THRESHOLD 494
> +#define ST_ADC_CAL_BATTI_UPPER_THRESHOLD 530
> +#define ST_ADC_CAL_BATTI_LOWER_THRESHOLD 494
> +#define ST_ADC_CALIBRATE_DIFF_THRESHOLD	3
> +
> +/**
> + * struct cpcap_adc_ato - timing settings for cpcap adc
> + *
> + * Unfortunately no cpcap documentation available, please document when
> + * using these.
> + */
> +struct cpcap_adc_ato {
> +	unsigned short ato_in;
> +	unsigned short atox_in;
> +	unsigned short adc_ps_factor_in;
> +	unsigned short atox_ps_factor_in;
> +	unsigned short ato_out;
> +	unsigned short atox_out;
> +	unsigned short adc_ps_factor_out;
> +	unsigned short atox_ps_factor_out;
> +};
> +
> +/**
> + * struct cpcap-adc - cpcap adc device driver data
> + * @reg: cpcap regmap
> + * @dev: struct device
> + * @vendor: cpcap vendor
> + * @irq: interrupt
> + * @lock: mutex
> + * @ato: request timings
> + * @wq_data_avail: work queue
> + * @done: work done
> + */
> +struct cpcap_adc {
> +	struct regmap *reg;
> +	struct device *dev;
> +	u16 vendor;
> +	int irq;
> +	struct mutex lock;	/* ADC register access lock */
> +	const struct cpcap_adc_ato *ato;
> +	wait_queue_head_t wq_data_avail;
> +	bool done;
> +};
> +
> +/**
> + * enum cpcap_adc_bank0 - cpcap adc bank0 channels
> + */
> +enum cpcap_adc_bank0 {
> +	CPCAP_ADC_AD0_BATTDETB,
> +	CPCAP_ADC_BATTP,
> +	CPCAP_ADC_VBUS,
> +	CPCAP_ADC_AD3,
> +	CPCAP_ADC_BPLUS_AD4,
> +	CPCAP_ADC_CHG_ISENSE,
> +	CPCAP_ADC_BATTI_ADC,
> +	CPCAP_ADC_USB_ID,
> +	CPCAP_ADC_BANK0_NUM,
> +};
> +
> +/**
> + * enum cpcap_adc_bank1 - cpcap adc bank1 channels
> + */
> +enum cpcap_adc_bank1 {
> +	CPCAP_ADC_AD8,
> +	CPCAP_ADC_AD9,
> +	CPCAP_ADC_LICELL,
> +	CPCAP_ADC_HV_BATTP,
> +	CPCAP_ADC_TSX1_AD12,
> +	CPCAP_ADC_TSX2_AD13,
> +	CPCAP_ADC_TSY1_AD14,
> +	CPCAP_ADC_TSY2_AD15,
> +	CPCAP_ADC_BANK1_NUM,
> +};
> +
> +/**
> + * enum cpcap_adc_timing - cpcap adc timing options
> + *
> + * CPCAP_ADC_TIMING_IMM seems to be immediate with no timings.
> + * Please document when using.
> + */
> +enum cpcap_adc_timing {
> +	CPCAP_ADC_TIMING_IMM,
> +	CPCAP_ADC_TIMING_IN,
> +	CPCAP_ADC_TIMING_OUT,
> +};
> +
> +/**
> + * enum cpcap_adc_type - cpcap adc types
> + *
> + * Two banks of channels with eight channels in each. The first two channels
> + * in bank0 can be muxed for other functionality with CPCAP_ADC_TYPE_BATT_PI.
> + */
> +enum cpcap_adc_type {
> +	CPCAP_ADC_TYPE_BANK_0,
> +	CPCAP_ADC_TYPE_BANK_1,
> +	CPCAP_ADC_TYPE_BATT_PI,
> +};
> +
> +/**
> + * struct cpcap_adc_request - cpcap adc request
> + * @timing: timing settings
> + * @type: bank type, bank0, 1 or remuxed bank0
> + * @result: result array
> + */
> +struct cpcap_adc_request {
> +	enum cpcap_adc_timing timing;
> +	enum cpcap_adc_type type;
> +	int result[CPCAP_ADC_BANK0_NUM];
> +};
> +
> +/**
> + * struct cpcap_adc_phasing_tbl - cpcap phasing table
> + * @offset: offset in the phasing table
> + * @multiplier: multiplier in the phasing table
> + * @divider: divider in the phasing table
> + * @min: minimum value
> + * @max: maximum value
> + */
> +struct cpcap_adc_phasing_tbl {
> +	short offset;
> +	unsigned short multiplier;
> +	unsigned short divider;
> +	short min;
> +	short max;
> +};
> +
> +/**
> + * enum cpcap_adc_conv_type - cpcap conversion types
> + */
> +enum cpcap_adc_conv_type {
> +	CONV_TYPE_NONE,
> +	CONV_TYPE_DIRECT,
> +	CONV_TYPE_MAPPING,
> +};
> +
> +/**
> + * struct cpcap_adc_conversion_tbl - cpcap conversion table
> + * @conv_type: conversion type
> + * @align_offset: align offset
> + * @conv_offset: conversion offset
> + * @cal_offset: calibration offset
> + * @multiplier: conversion multiplier
> + * @divider: conversion divider
> + */
> +struct cpcap_adc_conversion_tbl {
> +	enum cpcap_adc_conv_type conv_type;
> +	int align_offset;
> +	int conv_offset;
> +	int cal_offset;
> +	int multiplier;
> +	int divider;
> +};
> +
> +/* Phasing table for bank0 */
> +static struct cpcap_adc_phasing_tbl bank0_phasing[CPCAP_ADC_BANK0_NUM] = {

const

> +	[CPCAP_ADC_AD0_BATTDETB] = {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_BATTP] =        {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_VBUS] =         {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_AD3] =          {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_BPLUS_AD4] =    {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_CHG_ISENSE] =   {0, 0x80, 0x80, -512,  511},
> +	[CPCAP_ADC_BATTI_ADC] =    {0, 0x80, 0x80, -512,  511},
> +	[CPCAP_ADC_USB_ID] =       {0, 0x80, 0x80,    0, 1023},
> +};
> +
> +/* Phasing table for bank1 */
> +static struct cpcap_adc_phasing_tbl bank1_phasing[CPCAP_ADC_BANK1_NUM] = {

const

> +	[CPCAP_ADC_AD8] =          {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_AD9] =          {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_LICELL] =       {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_HV_BATTP] =     {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_TSX1_AD12] =    {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_TSX2_AD13] =    {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_TSY1_AD14] =    {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_TSY2_AD15] =    {0, 0x80, 0x80,    0, 1023},
> +};
> +
> +/* Conversion table for bank0 */
> +static struct cpcap_adc_conversion_tbl bank0_conversion[CPCAP_ADC_BANK0_NUM] = {

const

> +	[CPCAP_ADC_AD0_BATTDETB] = {
> +		CONV_TYPE_MAPPING,   0,    0, 0,     1,    1,
> +	},
> +	[CPCAP_ADC_BATTP] = {
> +		CONV_TYPE_DIRECT,    0, 2400, 0,  2300, 1023,
> +	},
> +	[CPCAP_ADC_VBUS] = {
> +		CONV_TYPE_DIRECT,    0,    0, 0, 10000, 1023,
> +	},
> +	[CPCAP_ADC_AD3] = {
> +		CONV_TYPE_MAPPING,   0,    0, 0,     1,    1,
> +		},
> +	[CPCAP_ADC_BPLUS_AD4] = {
> +		CONV_TYPE_DIRECT,    0, 2400, 0,  2300, 1023,
> +	},
> +	[CPCAP_ADC_CHG_ISENSE] = {
> +		CONV_TYPE_DIRECT, -512,    2, 0,  5000, 1023,
> +	},
> +	[CPCAP_ADC_BATTI_ADC] = {
> +		CONV_TYPE_DIRECT, -512,    2, 0,  5000, 1023,
> +	},
> +	[CPCAP_ADC_USB_ID] = {
> +		CONV_TYPE_NONE,      0,    0, 0,     1,    1,
> +	},
> +};
> +
> +/* Conversion table for bank1 */
> +static struct cpcap_adc_conversion_tbl bank1_conversion[CPCAP_ADC_BANK1_NUM] = {

const

> +	[CPCAP_ADC_AD8] =          {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_AD9] =          {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_LICELL] =       {CONV_TYPE_DIRECT, 0,  0,  0, 3400, 1023},
> +	[CPCAP_ADC_HV_BATTP] =     {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_TSX1_AD12] =    {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_TSX2_AD13] =    {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_TSY1_AD14] =    {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_TSY2_AD15] =    {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +};
> +
> +/*
> + * Temperature lookup table of register values to milliCelcius.
> + * REVISIT: Check the duplicate 0x3ff entry in a freezer
> + */
> +static const int temp_map[MAX_TEMP_LVL][2] = {
> +	{ 0x03ff, -40000 },
> +	{ 0x03ff, -35000 },
> +	{ 0x03ef, -30000 },
> +	{ 0x03b2, -25000 },
> +	{ 0x036c, -20000 },
> +	{ 0x0320, -15000 },
> +	{ 0x02d0, -10000 },
> +	{ 0x027f, -5000 },
> +	{ 0x022f, 0 },
> +	{ 0x01e4, 5000 },
> +	{ 0x019f, 10000 },
> +	{ 0x0161, 15000 },
> +	{ 0x012b, 20000 },
> +	{ 0x00fc, 25000 },
> +	{ 0x00d4, 30000 },
> +	{ 0x00b2, 35000 },
> +	{ 0x0095, 40000 },
> +	{ 0x007d, 45000 },
> +	{ 0x0069, 50000 },
> +	{ 0x0059, 55000 },
> +	{ 0x004b, 60000 },
> +	{ 0x003f, 65000 },
> +	{ 0x0036, 70000 },
> +	{ 0x002e, 75000 },
> +	{ 0x0027, 80000 },
> +	{ 0x0022, 85000 },
> +	{ 0x001d, 90000 },
> +};
> +
> +static irqreturn_t cpcap_adc_irq_thread(int irq, void *data)
> +{
> +	struct iio_dev *indio_dev = data;
> +	struct cpcap_adc *ddata = iio_priv(indio_dev);
> +	int error;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ADTRIG_DIS,
> +				   CPCAP_BIT_ADTRIG_DIS);
> +	if (error)
> +		return IRQ_NONE;
> +
> +	ddata->done = true;
> +	wake_up_interruptible(&ddata->wq_data_avail);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +#define CPCAP_CHAN(_type, _index, _address, _datasheet_name) {	\
> +	.type = (_type), \
> +	.address = (_address), \
> +	.indexed = 1, \
> +	.channel = (_index), \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> +			      BIT(IIO_CHAN_INFO_SCALE), \
> +	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> +				   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \

I don't see SAMP_FREQ and _OVERSAMPLING handled?

> +	.scan_index = (_index), \
> +	.scan_type = { \
> +		.sign = 'u', \
> +		.realbits = 10, \
> +		.storagebits = 16, \
> +		.endianness = IIO_CPU, \
> +	}, \
> +	.datasheet_name = (_datasheet_name), \
> +}
> +
> +/*
> + * The datasheet names are from Motorola mapphone Linux kernel except
> + * for the last two which might be uncalibrated charge voltage and
> + * current.
> + */
> +static const struct iio_chan_spec cpcap_adc_channels[] = {
> +	CPCAP_CHAN(IIO_TEMP, 0, CPCAP_REG_ADCD0, "battdetb"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 1, CPCAP_REG_ADCD1, "battp"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 2, CPCAP_REG_ADCD2, "vbus"),
> +	CPCAP_CHAN(IIO_TEMP, 3, CPCAP_REG_ADCD3, "ad3"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 4, CPCAP_REG_ADCD4, "ad4"),
> +	CPCAP_CHAN(IIO_CURRENT, 5, CPCAP_REG_ADCD5, "chg_isense"),
> +	CPCAP_CHAN(IIO_CURRENT, 6, CPCAP_REG_ADCD6, "batti"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 7, CPCAP_REG_ADCD7, "usb_id"),
> +
> +	CPCAP_CHAN(IIO_CURRENT, 8, CPCAP_REG_ADCD0, "ad8"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 9, CPCAP_REG_ADCD1, "ad9"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 10, CPCAP_REG_ADCD2, "licell"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 11, CPCAP_REG_ADCD3, "hv_battp"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 12, CPCAP_REG_ADCD4, "tsx1_ad12"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 13, CPCAP_REG_ADCD5, "tsx2_ad13"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 14, CPCAP_REG_ADCD6, "tsy1_ad14"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 15, CPCAP_REG_ADCD7, "tsy2_ad15"),
> +
> +	/* There are two registers with multiplexed functionality */
> +	CPCAP_CHAN(IIO_VOLTAGE, 16, CPCAP_REG_ADCD0, "chg_vsense"),
> +	CPCAP_CHAN(IIO_CURRENT, 17, CPCAP_REG_ADCD1, "batti2"),
> +};
> +
> +/* ADC calibration functions */
> +

drop newline

> +static void cpcap_adc_setup_calibrate(struct cpcap_adc *ddata,
> +				      enum cpcap_adc_bank0 chan)
> +{
> +	unsigned int value = 0;
> +	unsigned long timeout = jiffies + msecs_to_jiffies(3000);
> +	int error;
> +
> +	if ((chan != CPCAP_ADC_CHG_ISENSE) &&
> +	    (chan != CPCAP_ADC_BATTI_ADC))
> +		return;
> +
> +	value |= CPCAP_BIT_CAL_MODE | CPCAP_BIT_RAND0;
> +	value |= ((chan << 4) &
> +		  (CPCAP_BIT_ADA2 | CPCAP_BIT_ADA1 | CPCAP_BIT_ADA0));
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC1,
> +				   CPCAP_BIT_CAL_MODE | CPCAP_BIT_ATOX |
> +				   CPCAP_BIT_ATO3 | CPCAP_BIT_ATO2 |
> +				   CPCAP_BIT_ATO1 | CPCAP_BIT_ATO0 |
> +				   CPCAP_BIT_ADA2 | CPCAP_BIT_ADA1 |
> +				   CPCAP_BIT_ADA0 | CPCAP_BIT_AD_SEL1 |
> +				   CPCAP_BIT_RAND1 | CPCAP_BIT_RAND0,
> +				   value);
> +	if (error)
> +		return;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ATOX_PS_FACTOR |
> +				   CPCAP_BIT_ADC_PS_FACTOR1 |
> +				   CPCAP_BIT_ADC_PS_FACTOR0,
> +				   0);
> +	if (error)
> +		return;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ADTRIG_DIS,
> +				   CPCAP_BIT_ADTRIG_DIS);
> +	if (error)
> +		return;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ASC,
> +				   CPCAP_BIT_ASC);
> +	if (error)
> +		return;
> +
> +	do {
> +		schedule_timeout_uninterruptible(1);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCC2, &value);
> +		if (error)
> +			return;
> +	} while ((value & CPCAP_BIT_ASC) && time_before(jiffies, timeout));
> +
> +	if (value & CPCAP_BIT_ASC)
> +		dev_err(ddata->dev,
> +			"Timeout waiting for calibration to complete\n");
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC1,
> +				   CPCAP_BIT_CAL_MODE, 0);
> +	if (error)
> +		return;
> +}
> +
> +static int cpcap_adc_calibrate(struct cpcap_adc *ddata)
> +{
> +	unsigned int cal_data[2];
> +	unsigned short cal_data_diff;
> +	int i, error;
> +
> +	i = 0;
> +	do {
> +		cal_data[0]  = 0;
> +		cal_data[1]  = 0;
> +		cal_data_diff = 0;
> +		cpcap_adc_setup_calibrate(ddata, CPCAP_ADC_CHG_ISENSE);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL1, &cal_data[0]);
> +		if (error)
> +			return error;
> +		cpcap_adc_setup_calibrate(ddata, CPCAP_ADC_CHG_ISENSE);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL1, &cal_data[1]);
> +		if (error)
> +			return error;
> +
> +		if (cal_data[0] > cal_data[1])
> +			cal_data_diff = cal_data[0] - cal_data[1];
> +		else
> +			cal_data_diff = cal_data[1] - cal_data[0];
> +
> +		if (((cal_data[1] >= ST_ADC_CAL_CHRGI_LOWER_THRESHOLD) &&
> +		     (cal_data[1] <= ST_ADC_CAL_CHRGI_UPPER_THRESHOLD) &&
> +		     (cal_data_diff <= ST_ADC_CALIBRATE_DIFF_THRESHOLD)) ||
> +		    (ddata->vendor == CPCAP_VENDOR_TI)) {
> +			bank0_conversion[CPCAP_ADC_CHG_ISENSE].cal_offset =
> +				((short)cal_data[1] * -1) + 512;
> +			dev_info(ddata->dev,
> +				 "cpcap_adc_probe: CHRGI Cal complete!\n");

maybe calibration instead of Cal

> +			break;
> +		}
> +
> +		msleep(5);

I guess this will trigger a checkpatch warning

> +		i++;
> +	} while (i > 5);

should be < 5????
why not just use a for look?

> +
> +	i = 0;
> +	do {

can't this code duplication be avoided?

> +		cal_data[0]  = 0;
> +		cal_data[1]  = 0;
> +		cal_data_diff = 0;
> +		cpcap_adc_setup_calibrate(ddata, CPCAP_ADC_BATTI_ADC);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL2, &cal_data[0]);
> +		if (error)
> +			return error;
> +		cpcap_adc_setup_calibrate(ddata, CPCAP_ADC_BATTI_ADC);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL2, &cal_data[1]);
> +		if (error)
> +			return error;
> +
> +		if (cal_data[0] > cal_data[1])
> +			cal_data_diff = cal_data[0] - cal_data[1];
> +		else
> +			cal_data_diff = cal_data[1] - cal_data[0];
> +
> +		if (((cal_data[1] >= ST_ADC_CAL_BATTI_LOWER_THRESHOLD) &&
> +		     (cal_data[1] <= ST_ADC_CAL_BATTI_UPPER_THRESHOLD) &&
> +		     (cal_data_diff <= ST_ADC_CALIBRATE_DIFF_THRESHOLD)) ||
> +		    (ddata->vendor == CPCAP_VENDOR_TI)) {
> +			bank0_conversion[CPCAP_ADC_BATTI_ADC].cal_offset =
> +				((short)cal_data[1] * -1) + 512;
> +			dev_info(ddata->dev,
> +				 "cpcap_adc_probe: BATTI Cal complete!\n");
> +			break;
> +		}
> +
> +		msleep(5);

I guess this will trigger a checkpatch warning

> +		i++;
> +	} while (i > 5);

should be < 5????

> +
> +	return 0;
> +}
> +
> +/* ADC setup, read and scale functions */


drop newline

> +
> +static void cpcap_adc_setup_bank(struct cpcap_adc *ddata,
> +				 enum cpcap_adc_type type,
> +				 enum cpcap_adc_timing timing)
> +{
> +	const struct cpcap_adc_ato *ato = ddata->ato;
> +	unsigned short value1 = 0;
> +	unsigned short value2 = 0;
> +	int error;
> +
> +	if (!ato)
> +		return;
> +
> +	if (type == CPCAP_ADC_TYPE_BANK_1)
> +		value1 |= CPCAP_BIT_AD_SEL1;
> +	else if (type == CPCAP_ADC_TYPE_BATT_PI)
> +		value1 |= CPCAP_BIT_RAND1;
> +
> +	switch (timing) {
> +	case CPCAP_ADC_TIMING_IN:
> +		value1 |= ato->ato_in;
> +		value1 |= ato->atox_in;
> +		value2 |= ato->adc_ps_factor_in;
> +		value2 |= ato->atox_ps_factor_in;
> +		break;
> +
> +	case CPCAP_ADC_TIMING_OUT:
> +		value1 |= ato->ato_out;
> +		value1 |= ato->atox_out;
> +		value2 |= ato->adc_ps_factor_out;
> +		value2 |= ato->atox_ps_factor_out;
> +		break;
> +
> +	case CPCAP_ADC_TIMING_IMM:
> +	default:
> +		break;
> +	}
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC1,
> +				   CPCAP_BIT_CAL_MODE | CPCAP_BIT_ATOX |
> +				   CPCAP_BIT_ATO3 | CPCAP_BIT_ATO2 |
> +				   CPCAP_BIT_ATO1 | CPCAP_BIT_ATO0 |
> +				   CPCAP_BIT_ADA2 | CPCAP_BIT_ADA1 |
> +				   CPCAP_BIT_ADA0 | CPCAP_BIT_AD_SEL1 |
> +				   CPCAP_BIT_RAND1 | CPCAP_BIT_RAND0,
> +				   value1);
> +	if (error)
> +		return;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ATOX_PS_FACTOR |
> +				   CPCAP_BIT_ADC_PS_FACTOR1 |
> +				   CPCAP_BIT_ADC_PS_FACTOR0,
> +				   value2);
> +	if (error)
> +		return;
> +
> +	if (timing == CPCAP_ADC_TIMING_IMM) {
> +		error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +					   CPCAP_BIT_ADTRIG_DIS,
> +					   CPCAP_BIT_ADTRIG_DIS);
> +		if (error)
> +			return;
> +
> +		error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +					   CPCAP_BIT_ASC,
> +					   CPCAP_BIT_ASC);
> +		if (error)
> +			return;
> +	} else {
> +		error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +					   CPCAP_BIT_ADTRIG_ONESHOT,
> +					   CPCAP_BIT_ADTRIG_ONESHOT);
> +		if (error)
> +			return;
> +
> +		error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +					   CPCAP_BIT_ADTRIG_DIS, 0);
> +		if (error)
> +			return;
> +	}
> +}
> +
> +/*
> + * Occasionally the ADC does not seem to start and there will be no
> + * interrupt. Let's re-init interrupt to prevent the ADC from hanging
> + * for the next request. It is unclear why this happens, but the next
> + * request will usually work after doing this.
> + */
> +static void cpcap_adc_quirk_reset_lost_irq(struct cpcap_adc *ddata)
> +{
> +	int error;
> +
> +	dev_info(ddata->dev, "lost ADC irq, attempting to reinit\n");
> +	disable_irq(ddata->irq);
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ADTRIG_DIS,
> +				   CPCAP_BIT_ADTRIG_DIS);
> +	if (error)
> +		dev_warn(ddata->dev, "%s reset failed: %i\n",
> +			 __func__, error);
> +	enable_irq(ddata->irq);
> +}
> +
> +static int cpcap_adc_start_bank(struct cpcap_adc *ddata,
> +				struct cpcap_adc_request *req)
> +{
> +	int i, error;
> +
> +	req->timing = CPCAP_ADC_TIMING_IMM;
> +	ddata->done = false;
> +
> +	for (i = 0; i < 5; i++) {
> +		cpcap_adc_setup_bank(ddata, req->type, req->timing);
> +		error = wait_event_interruptible_timeout(ddata->wq_data_avail,
> +							 ddata->done,
> +							 msecs_to_jiffies(50));
> +		if (error >= 0)
> +			return 0;
> +
> +		if (error == 0) {

error has been checked >= 0 above already?!

> +			cpcap_adc_quirk_reset_lost_irq(ddata);
> +			error = -ETIMEDOUT;
> +			continue;
> +		}
> +
> +		if (error < 0)
> +			return error;
> +	}
> +
> +	return error;
> +}
> +
> +static void cpcap_adc_phase(struct cpcap_adc_request *req, int index)
> +{
> +	struct cpcap_adc_conversion_tbl *conv_tbl = bank0_conversion;
> +	struct cpcap_adc_phasing_tbl *phase_tbl = bank0_phasing;
> +	int tbl_index = index;
> +
> +	if (req->type == CPCAP_ADC_TYPE_BANK_1) {
> +		conv_tbl = bank1_conversion;
> +		phase_tbl = bank1_phasing;
> +	}
> +
> +	if (req->type == CPCAP_ADC_TYPE_BATT_PI)
> +		tbl_index = (tbl_index % 2) ? CPCAP_ADC_BATTI_ADC :
> +			CPCAP_ADC_BATTP;
> +
> +	if (((req->type == CPCAP_ADC_TYPE_BANK_0) ||
> +	     (req->type == CPCAP_ADC_TYPE_BATT_PI)) &&
> +	    (tbl_index == CPCAP_ADC_BATTP)) {
> +		req->result[index] -= phase_tbl[tbl_index].offset;
> +		req->result[index] -= FOUR_POINT_TWO_ADC;
> +		req->result[index] *= phase_tbl[tbl_index].multiplier;
> +		if (phase_tbl[tbl_index].divider == 0)
> +			return;
> +		req->result[index] /= phase_tbl[tbl_index].divider;
> +		req->result[index] += FOUR_POINT_TWO_ADC;
> +	} else {
> +		req->result[index] += conv_tbl[tbl_index].cal_offset;
> +		req->result[index] += conv_tbl[tbl_index].align_offset;
> +		req->result[index] *= phase_tbl[tbl_index].multiplier;
> +		if (phase_tbl[tbl_index].divider == 0)
> +			return;
> +		req->result[index] /= phase_tbl[tbl_index].divider;
> +		req->result[index] += phase_tbl[tbl_index].offset;
> +	}
> +
> +	if (req->result[index] < phase_tbl[tbl_index].min)
> +		req->result[index] = phase_tbl[tbl_index].min;
> +	else if (req->result[index] > phase_tbl[tbl_index].max)
> +		req->result[index] = phase_tbl[tbl_index].max;
> +}
> +
> +/* Looks up temperatures in a table and calculates averages if needed */
> +static unsigned short cpcap_adc_table_to_millicelcius(unsigned short value)

why unsigned if it returns millicelcius, shouldn't this be int to cover 
the temperature rate?

> +{
> +	int i;
> +	int result = 0, alpha = 0;

initialization not needed

> +
> +	if (value <= temp_map[MAX_TEMP_LVL - 1][0])
> +		return temp_map[MAX_TEMP_LVL - 1][1];
> +
> +	if (value >= temp_map[0][0])
> +		return temp_map[0][1];
> +
> +	for (i = 0; i < MAX_TEMP_LVL - 1; i++) {
> +		if ((value <= temp_map[i][0]) &&
> +		    (value >= temp_map[i + 1][0])) {
> +			if (value == temp_map[i][0]) {
> +				result = temp_map[i][1];
> +			} else if (value == temp_map[i + 1][0]) {
> +				result = temp_map[i + 1][1];
> +			} else {
> +				alpha = ((value - temp_map[i][0]) * 1000) /
> +					(temp_map[i + 1][0] - temp_map[i][0]);
> +
> +				result = temp_map[i][1] +
> +					((alpha * (temp_map[i + 1][1] -
> +						 temp_map[i][1])) / 1000);
> +			}
> +			break;
> +		}
> +	}
> +
> +	return result;
> +}
> +
> +static void cpcap_adc_convert(struct cpcap_adc_request *req, int index)
> +{
> +	struct cpcap_adc_conversion_tbl *conv_tbl = bank0_conversion;
> +	int tbl_index = index;
> +
> +	if (req->type == CPCAP_ADC_TYPE_BANK_1)
> +		conv_tbl = bank1_conversion;
> +
> +	if (req->type == CPCAP_ADC_TYPE_BATT_PI)
> +		tbl_index = (tbl_index % 2) ? CPCAP_ADC_BATTI_ADC :
> +			    CPCAP_ADC_BATTP;
> +
> +	if (conv_tbl[tbl_index].conv_type == CONV_TYPE_DIRECT) {
> +		req->result[index] *= conv_tbl[tbl_index].multiplier;
> +		if (conv_tbl[tbl_index].divider == 0)
> +			return;
> +		req->result[index] /= conv_tbl[tbl_index].divider;
> +		req->result[index] += conv_tbl[tbl_index].conv_offset;
> +	} else if (conv_tbl[tbl_index].conv_type == CONV_TYPE_MAPPING)
> +		req->result[index] =
> +			cpcap_adc_table_to_millicelcius(req->result[tbl_index]);
> +}
> +
> +static int cpcap_adc_read_bank_scaled(struct cpcap_adc *ddata,
> +				      struct cpcap_adc_request *req,
> +				      const unsigned long channel_mask)
> +{
> +	unsigned int i;
> +	int cal_data, error;
> +
> +	if (ddata->vendor == CPCAP_VENDOR_TI) {
> +		cal_data = 0;
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL1, &cal_data);
> +		if (error)
> +			return error;
> +		bank0_conversion[CPCAP_ADC_CHG_ISENSE].cal_offset =
> +			((short)cal_data * -1) + 512;
> +	}
> +
> +	if (ddata->vendor == CPCAP_VENDOR_TI) {
> +		cal_data = 0;
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL2, &cal_data);
> +		if (error)
> +			return error;
> +		bank0_conversion[CPCAP_ADC_BATTI_ADC].cal_offset =
> +			((short)cal_data * -1) + 512;
> +	}
> +
> +	for_each_set_bit(i, &channel_mask, 8) {
> +		int addr = CPCAP_REG_ADCD0 + i * 4;
> +
> +		error = regmap_read(ddata->reg, addr, &req->result[i]);
> +		if (error)
> +			return error;
> +
> +		req->result[i] &= 0x3ff;
> +		cpcap_adc_phase(req, i);
> +		cpcap_adc_convert(req, i);
> +	}
> +
> +	return 0;
> +}
> +
> +static int cpcap_adc_read(struct iio_dev *indio_dev,
> +			  struct iio_chan_spec const *chan,
> +			  int *val, int *val2, long mask)
> +{
> +	struct cpcap_adc *ddata = iio_priv(indio_dev);
> +	struct cpcap_adc_request req;
> +	int index, error;
> +
> +	if (chan->channel < 8) {
> +		index = chan->channel;
> +		req.type = CPCAP_ADC_TYPE_BANK_0;
> +	} else if (chan->channel < 16) {
> +		index = chan->channel - 8;
> +		req.type = CPCAP_ADC_TYPE_BANK_1;
> +	} else if (chan->channel < 18) {
> +		index = chan->channel - 16;
> +		req.type = CPCAP_ADC_TYPE_BATT_PI;
> +	} else {
> +		return -EINVAL;
> +	}
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&ddata->lock);
> +		error = cpcap_adc_start_bank(ddata, &req);
> +		if (error)
> +			goto err_unlock;
> +		error = regmap_read(ddata->reg, chan->address, val);
> +		if (error)
> +			goto err_unlock;
> +		mutex_unlock(&ddata->lock);
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		mutex_lock(&ddata->lock);
> +		error = cpcap_adc_start_bank(ddata, &req);
> +		if (error)
> +			goto err_unlock;
> +		error = cpcap_adc_read_bank_scaled(ddata, &req, BIT(index));
> +		if (error)
> +			goto err_unlock;
> +		mutex_unlock(&ddata->lock);
> +		*val = req.result[index];
> +		break;
> +	default:

-EINVAL here?

> +		break;
> +	}
> +
> +	return IIO_VAL_INT;
> +
> +err_unlock:
> +	mutex_unlock(&ddata->lock);
> +	dev_err(ddata->dev, "error reading ADC: %i\n", error);
> +
> +	return error;
> +}
> +
> +static const struct iio_info cpcap_adc_info = {
> +	.read_raw = &cpcap_adc_read,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +/*
> + * Configuration for Motorola mapphone series such as droid 4.
> + * Copied from the Motorola mapphone kernel tree.
> + */
> +static const struct cpcap_adc_ato mapphone_adc = {
> +	.ato_in = 0x0480,
> +	.atox_in = 0,
> +	.adc_ps_factor_in = 0x0200,
> +	.atox_ps_factor_in = 0,
> +	.ato_out = 0,
> +	.atox_out = 0,
> +	.adc_ps_factor_out = 0,
> +	.atox_ps_factor_out = 0,
> +};
> +
> +static const struct of_device_id cpcap_adc_id_table[] = {
> +	{
> +		.compatible = "motorola,cpcap-adc",
> +	},
> +	{
> +		.compatible = "motorola,mapphone-cpcap-adc",
> +		.data = &mapphone_adc,
> +	},
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, cpcap_adc_id_table);
> +
> +static int cpcap_adc_probe(struct platform_device *pdev)
> +{
> +	const struct of_device_id *match;
> +	struct cpcap_adc *ddata;
> +	struct iio_dev *indio_dev;
> +	struct iio_buffer *buf;
> +	int error;
> +
> +	match = of_match_device(of_match_ptr(cpcap_adc_id_table),
> +				&pdev->dev);
> +	if (!match)
> +		return -EINVAL;
> +
> +	if (!match->data) {
> +		dev_err(&pdev->dev, "no configuration data found\n");
> +
> +		return -ENODEV;
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*ddata));
> +	if (!indio_dev) {
> +		dev_err(&pdev->dev, "failed to allocate iio device\n");
> +
> +		return -ENOMEM;
> +	}
> +	ddata = iio_priv(indio_dev);
> +	ddata->ato = match->data;
> +	ddata->dev = &pdev->dev;
> +
> +	mutex_init(&ddata->lock);
> +	init_waitqueue_head(&ddata->wq_data_avail);
> +
> +	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->dev.of_node = pdev->dev.of_node;
> +	indio_dev->channels = cpcap_adc_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(cpcap_adc_channels);
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->info = &cpcap_adc_info;
> +
> +	ddata->reg = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!ddata->reg)
> +		return -ENODEV;
> +
> +	error = cpcap_get_vendor(ddata->dev, ddata->reg, &ddata->vendor);
> +	if (error)
> +		return error;
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	ddata->irq = platform_get_irq_byname(pdev, "adcdone");
> +	if (!ddata->irq)
> +		return -ENODEV;
> +
> +	error = devm_request_threaded_irq(&pdev->dev, ddata->irq, NULL,
> +					  cpcap_adc_irq_thread, IRQ_NONE,
> +					  "cpcap-adc", indio_dev);
> +	if (error) {
> +		dev_err(&pdev->dev, "could not get irq: %i\n",
> +			error);
> +
> +		return error;
> +	}
> +
> +	error = cpcap_adc_calibrate(ddata);
> +	if (error)
> +		return error;
> +
> +	buf = devm_iio_kfifo_allocate(&indio_dev->dev);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	iio_device_attach_buffer(indio_dev, buf);
> +
> +	dev_info(&pdev->dev, "CPCAP ADC device probed\n");
> +
> +	return iio_device_register(indio_dev);
> +}
> +
> +static int cpcap_adc_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver cpcap_adc_driver = {
> +	.driver = {
> +		.name = "cpcap_adc",
> +		.of_match_table = of_match_ptr(cpcap_adc_id_table),
> +	},
> +	.probe = cpcap_adc_probe,
> +	.remove = cpcap_adc_remove,
> +};
> +
> +module_platform_driver(cpcap_adc_driver);
> +
> +MODULE_ALIAS("platform:cpcap_adc");
> +MODULE_DESCRIPTION("CPCAP ADC driver");
> +MODULE_AUTHOR("Motorola and Tony Lindgren <tony@atomide.com");
> +MODULE_LICENSE("GPL v2");
>

Hi,

* Peter Meerwald-Stadler <pmeerw@pmeerw.net> [170316 23:44]:
> > Signed-off-by: Tony Lindgrne <tony@atomide.com>
> 
> Lindgren

Hmm yeah there are slight variations to my signature it seems :)
...

> > +/* Register CPCAP_REG_ADCC1 bits */
> > +#define CPCAP_BIT_ADEN_AUTO_CLR		BIT(15)	/* Currently unused */
> > +#define CPCAP_BIT_CAL_MODE		BIT(14) /* Set with BIT_RAND0 */
> > +#define CPCAP_BIT_ADC_CLK_SEL1		BIT(13)	/* Currently unused */
> > +#define CPCAP_BIT_ADC_CLK_SEL0		BIT(12)	/* Currently unused */
> > +#define CPCAP_BIT_ATOX			BIT(11)	/* in/out ps factor */
> 
> wondering what a 'ps' factor is...

I guess I have no idea at this point with no documentation. I'll
just drop the comments for now for the mystery registers.

> > +#define CPCAP_CHAN(_type, _index, _address, _datasheet_name) {	\
> > +	.type = (_type), \
> > +	.address = (_address), \
> > +	.indexed = 1, \
> > +	.channel = (_index), \
> > +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> > +			      BIT(IIO_CHAN_INFO_SCALE), \
> > +	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> > +				   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
> 
> I don't see SAMP_FREQ and _OVERSAMPLING handled?

OK will drop for now.

> > +			dev_info(ddata->dev,
> > +				 "cpcap_adc_probe: CHRGI Cal complete!\n");
> 
> maybe calibration instead of Cal

Yup thanks, also can use __func__ or just driver name.

> > +			break;
> > +		}
> > +
> > +		msleep(5);
> 
> I guess this will trigger a checkpatch warning
> 
> > +		i++;
> > +	} while (i > 5);
> 
> should be < 5????
> why not just use a for look?

Heheh yeah that looks really weird :) I guess I was too chicken to mess
with the calibration for the battery ADCs earlier so I tried to keep it
as it was in the Motorola driver. But now things are working and I can
compare the results so it should not be a problem.

> can't this code duplication be avoided?

Yeah so it seems, I'll take a look.

> > +/* Looks up temperatures in a table and calculates averages if needed */
> > +static unsigned short cpcap_adc_table_to_millicelcius(unsigned short value)
> 
> why unsigned if it returns millicelcius, shouldn't this be int to cover 
> the temperature rate?

Thanks yes. It was Kelvins in the Motorola driver.

Will fix up the rest of your comments and repost. Thanks for looking
and thanks for the good comments.

Regards,

Tony
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On 17/03/17 01:43, Tony Lindgren wrote:
> On Motorola phones like droid 4 there is a custom CPCAP PMIC. This PMIC
> has ADCs that are used for battery charging and USB PHY VBUS and ID pin
> detection.
> 
> Unfortunately the only documentation for this ADC seems to be the
> Motorola mapphone Linux kernel tree. I have tested that reading raw and
> scaled values works, but I have not used the timed sampling that the ADC
> seems to support.
Any link? I'm curious to see just how 'interesting' this was...
> 
> Let's add a minimal support for it so we can eventually provide IIO
> channels for the related battery charging and USB PHY drivers.
> 
> Cc: devicetree@vger.kernel.org
> Cc: Marcel Partap <mpartap@gmx.net>
> Cc: Michael Scott <michael.scott@linaro.org>
> Cc: Sebastian Reichel <sre@kernel.org>
> Signed-off-by: Tony Lindgrne <tony@atomide.com>
You are a brave person...

A few comments inline to add to Peter's.
> ---
>  .../devicetree/bindings/iio/adc/cpcap-adc.txt      |  16 +
>  drivers/iio/adc/Kconfig                            |  11 +
>  drivers/iio/adc/Makefile                           |   1 +
>  drivers/iio/adc/cpcap-adc.c                        | 997 +++++++++++++++++++++
>  4 files changed, 1025 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt
>  create mode 100644 drivers/iio/adc/cpcap-adc.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt b/Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt
> new file mode 100644
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt
> @@ -0,0 +1,16 @@
> +Motorola CPCAP PMIC ADC binding
> +
> +Required properties:
> +- compatible: Should be "motorola,cpcap-adc" or "motorola,mapphone-cpcap-adc"
> +- interrupts: The interrupt number for the ADC device
> +- interrupt-names: Should be "adcdone"
> +- #io-channel-cells: Number of cells in an IIO specifier
> +
> +Example:
> +
> +cpcap_adc: adc {
> +	compatible = "motorola,mapphone-cpcap-adc";
> +	interrupts-extended = <&cpcap 8 0>;
> +	interrupt-names = "adcdone";
> +	#io-channel-cells = <1>;
> +};
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -195,6 +195,17 @@ config CC10001_ADC
>  	  This driver can also be built as a module. If so, the module will be
>  	  called cc10001_adc.
>  
> +config CPCAP_ADC
> +	tristate "Motorola CPCAP PMIC ADC driver"
> +	depends on MFD_CPCAP
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	help
> +	  Say yes here to build support for Motorola CPCAP PMIC ADC.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called cpcap-adc.
> +
>  config DA9150_GPADC
>  	tristate "Dialog DA9150 GPADC driver support"
>  	depends on MFD_DA9150
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -20,6 +20,7 @@ obj-$(CONFIG_AXP288_ADC) += axp288_adc.o
>  obj-$(CONFIG_BCM_IPROC_ADC) += bcm_iproc_adc.o
>  obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
>  obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
> +obj-$(CONFIG_CPCAP_ADC) += cpcap-adc.o
>  obj-$(CONFIG_DA9150_GPADC) += da9150-gpadc.o
>  obj-$(CONFIG_ENVELOPE_DETECTOR) += envelope-detector.o
>  obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
> diff --git a/drivers/iio/adc/cpcap-adc.c b/drivers/iio/adc/cpcap-adc.c
> new file mode 100644
> --- /dev/null
> +++ b/drivers/iio/adc/cpcap-adc.c
> @@ -0,0 +1,997 @@
> +/*
> + * Copyright (C) 2017 Tony Lindgren <tony@atomide.com>
> + *
> + * Rewritten for Linux IIO framework with register managing functions
> + * based on earlier driver found in the Motorola Linux kernel:
> + *
> + * Copyright (C) 2009-2010 Motorola, Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/driver.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/kfifo_buf.h>
> +#include <linux/mfd/motorola-cpcap.h>
> +
> +/* Register CPCAP_REG_ADCC1 bits */
> +#define CPCAP_BIT_ADEN_AUTO_CLR		BIT(15)	/* Currently unused */
> +#define CPCAP_BIT_CAL_MODE		BIT(14) /* Set with BIT_RAND0 */
> +#define CPCAP_BIT_ADC_CLK_SEL1		BIT(13)	/* Currently unused */
> +#define CPCAP_BIT_ADC_CLK_SEL0		BIT(12)	/* Currently unused */
> +#define CPCAP_BIT_ATOX			BIT(11)	/* in/out ps factor */
> +#define CPCAP_BIT_ATO3			BIT(10)
> +#define CPCAP_BIT_ATO2			BIT(9)
> +#define CPCAP_BIT_ATO1			BIT(8)
> +#define CPCAP_BIT_ATO0			BIT(7)
> +#define CPCAP_BIT_ADA2			BIT(6)
> +#define CPCAP_BIT_ADA1			BIT(5)
> +#define CPCAP_BIT_ADA0			BIT(4)
> +#define CPCAP_BIT_AD_SEL1		BIT(3)	/* Set for ADC_TYPE_BANK_1 */
> +#define CPCAP_BIT_RAND1			BIT(2)	/* Set for ADC_TYPE_BATT_PI */
> +#define CPCAP_BIT_RAND0			BIT(1)	/* Set with CAL_MODE */
> +#define CPCAP_BIT_ADEN			BIT(0)	/* Currently unused */
> +
> +/* Register CPCAP_REG_ADCC2 bits */
> +#define CPCAP_BIT_CAL_FACTOR_ENABLE	BIT(15)	/* Currently unused */
> +#define CPCAP_BIT_BATDETB_EN		BIT(14)	/* Currently unused */
> +#define CPCAP_BIT_ADTRIG_ONESHOT	BIT(13)	/* Set for !TIMING_IMM */
> +#define CPCAP_BIT_ASC			BIT(12)	/* Set for TIMING_IMM */
> +#define CPCAP_BIT_ATOX_PS_FACTOR	BIT(11)	/* in/out ps factor */
> +#define CPCAP_BIT_ADC_PS_FACTOR1	BIT(10)	/* in/out ps factor */
> +#define CPCAP_BIT_ADC_PS_FACTOR0	BIT(9)	/* in/out ps factor */
> +#define CPCAP_BIT_AD4_SELECT		BIT(8)	/* Currently unused */
> +#define CPCAP_BIT_ADC_BUSY		BIT(7)	/* Currently unused */
> +#define CPCAP_BIT_THERMBIAS_EN		BIT(6)	/* Currently unused */
> +#define CPCAP_BIT_ADTRIG_DIS		BIT(5)	/* Disable interrupt */
> +#define CPCAP_BIT_LIADC			BIT(4)	/* Currently unused */
> +#define CPCAP_BIT_TS_REFEN		BIT(3)	/* Currently unused */
> +#define CPCAP_BIT_TS_M2			BIT(2)	/* Currently unused */
> +#define CPCAP_BIT_TS_M1			BIT(1)	/* Currently unused */
> +#define CPCAP_BIT_TS_M0			BIT(0)	/* Currently unused */
> +
> +#define MAX_TEMP_LVL			27
> +#define FOUR_POINT_TWO_ADC		801
> +#define ST_ADC_CAL_CHRGI_UPPER_THRESHOLD 530
> +#define ST_ADC_CAL_CHRGI_LOWER_THRESHOLD 494
> +#define ST_ADC_CAL_BATTI_UPPER_THRESHOLD 530
> +#define ST_ADC_CAL_BATTI_LOWER_THRESHOLD 494
> +#define ST_ADC_CALIBRATE_DIFF_THRESHOLD	3
> +
> +/**
> + * struct cpcap_adc_ato - timing settings for cpcap adc
> + *
> + * Unfortunately no cpcap documentation available, please document when
> + * using these.
> + */
> +struct cpcap_adc_ato {
> +	unsigned short ato_in;
> +	unsigned short atox_in;
> +	unsigned short adc_ps_factor_in;
> +	unsigned short atox_ps_factor_in;
> +	unsigned short ato_out;
> +	unsigned short atox_out;
> +	unsigned short adc_ps_factor_out;
> +	unsigned short atox_ps_factor_out;
> +};
> +
> +/**
> + * struct cpcap-adc - cpcap adc device driver data
> + * @reg: cpcap regmap
> + * @dev: struct device
> + * @vendor: cpcap vendor
> + * @irq: interrupt
> + * @lock: mutex
> + * @ato: request timings
> + * @wq_data_avail: work queue
> + * @done: work done
> + */
> +struct cpcap_adc {
> +	struct regmap *reg;
> +	struct device *dev;
> +	u16 vendor;
> +	int irq;
> +	struct mutex lock;	/* ADC register access lock */
> +	const struct cpcap_adc_ato *ato;
> +	wait_queue_head_t wq_data_avail;
> +	bool done;
> +};
> +
> +/**
> + * enum cpcap_adc_bank0 - cpcap adc bank0 channels
> + */
> +enum cpcap_adc_bank0 {
> +	CPCAP_ADC_AD0_BATTDETB,
> +	CPCAP_ADC_BATTP,
> +	CPCAP_ADC_VBUS,
> +	CPCAP_ADC_AD3,
> +	CPCAP_ADC_BPLUS_AD4,
> +	CPCAP_ADC_CHG_ISENSE,
> +	CPCAP_ADC_BATTI_ADC,
> +	CPCAP_ADC_USB_ID,
> +	CPCAP_ADC_BANK0_NUM,
> +};
> +
> +/**
> + * enum cpcap_adc_bank1 - cpcap adc bank1 channels
> + */
> +enum cpcap_adc_bank1 {
> +	CPCAP_ADC_AD8,
> +	CPCAP_ADC_AD9,
> +	CPCAP_ADC_LICELL,
> +	CPCAP_ADC_HV_BATTP,
> +	CPCAP_ADC_TSX1_AD12,
> +	CPCAP_ADC_TSX2_AD13,
> +	CPCAP_ADC_TSY1_AD14,
> +	CPCAP_ADC_TSY2_AD15,
> +	CPCAP_ADC_BANK1_NUM,
> +};
> +
> +/**
> + * enum cpcap_adc_timing - cpcap adc timing options
> + *
> + * CPCAP_ADC_TIMING_IMM seems to be immediate with no timings.
> + * Please document when using.
> + */
> +enum cpcap_adc_timing {
> +	CPCAP_ADC_TIMING_IMM,
> +	CPCAP_ADC_TIMING_IN,
> +	CPCAP_ADC_TIMING_OUT,
> +};
> +
> +/**
> + * enum cpcap_adc_type - cpcap adc types
> + *
> + * Two banks of channels with eight channels in each. The first two channels
> + * in bank0 can be muxed for other functionality with CPCAP_ADC_TYPE_BATT_PI.
> + */
> +enum cpcap_adc_type {
> +	CPCAP_ADC_TYPE_BANK_0,
> +	CPCAP_ADC_TYPE_BANK_1,
> +	CPCAP_ADC_TYPE_BATT_PI,
> +};
> +
> +/**
> + * struct cpcap_adc_request - cpcap adc request
> + * @timing: timing settings
> + * @type: bank type, bank0, 1 or remuxed bank0
> + * @result: result array
> + */
> +struct cpcap_adc_request {
> +	enum cpcap_adc_timing timing;
> +	enum cpcap_adc_type type;
> +	int result[CPCAP_ADC_BANK0_NUM];
> +};
> +
> +/**
> + * struct cpcap_adc_phasing_tbl - cpcap phasing table
> + * @offset: offset in the phasing table
> + * @multiplier: multiplier in the phasing table
> + * @divider: divider in the phasing table
> + * @min: minimum value
> + * @max: maximum value
> + */
> +struct cpcap_adc_phasing_tbl {
> +	short offset;
> +	unsigned short multiplier;
> +	unsigned short divider;
> +	short min;
> +	short max;
> +};
> +
> +/**
> + * enum cpcap_adc_conv_type - cpcap conversion types
If you have figured out what these are, then added a comment on
them would be great.  I've no idea what mapping refers to1
> + */
> +enum cpcap_adc_conv_type {
> +	CONV_TYPE_NONE,
> +	CONV_TYPE_DIRECT,
> +	CONV_TYPE_MAPPING,
> +};
> +
> +/**
> + * struct cpcap_adc_conversion_tbl - cpcap conversion table
> + * @conv_type: conversion type
> + * @align_offset: align offset
> + * @conv_offset: conversion offset
> + * @cal_offset: calibration offset
> + * @multiplier: conversion multiplier
> + * @divider: conversion divider
> + */
> +struct cpcap_adc_conversion_tbl {
> +	enum cpcap_adc_conv_type conv_type;
> +	int align_offset;
> +	int conv_offset;
> +	int cal_offset;
> +	int multiplier;
> +	int divider;
> +};
> +
> +/* Phasing table for bank0 */
> +static struct cpcap_adc_phasing_tbl bank0_phasing[CPCAP_ADC_BANK0_NUM] = {
> +	[CPCAP_ADC_AD0_BATTDETB] = {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_BATTP] =        {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_VBUS] =         {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_AD3] =          {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_BPLUS_AD4] =    {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_CHG_ISENSE] =   {0, 0x80, 0x80, -512,  511},
> +	[CPCAP_ADC_BATTI_ADC] =    {0, 0x80, 0x80, -512,  511},
> +	[CPCAP_ADC_USB_ID] =       {0, 0x80, 0x80,    0, 1023},
> +};
> +
> +/* Phasing table for bank1 */
> +static struct cpcap_adc_phasing_tbl bank1_phasing[CPCAP_ADC_BANK1_NUM] = {
> +	[CPCAP_ADC_AD8] =          {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_AD9] =          {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_LICELL] =       {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_HV_BATTP] =     {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_TSX1_AD12] =    {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_TSX2_AD13] =    {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_TSY1_AD14] =    {0, 0x80, 0x80,    0, 1023},
> +	[CPCAP_ADC_TSY2_AD15] =    {0, 0x80, 0x80,    0, 1023},
> +};
> +
> +/* Conversion table for bank0 */
> +static struct cpcap_adc_conversion_tbl bank0_conversion[CPCAP_ADC_BANK0_NUM] = {
> +	[CPCAP_ADC_AD0_BATTDETB] = {
> +		CONV_TYPE_MAPPING,   0,    0, 0,     1,    1,
> +	},
> +	[CPCAP_ADC_BATTP] = {
> +		CONV_TYPE_DIRECT,    0, 2400, 0,  2300, 1023,
> +	},
> +	[CPCAP_ADC_VBUS] = {
> +		CONV_TYPE_DIRECT,    0,    0, 0, 10000, 1023,
> +	},
> +	[CPCAP_ADC_AD3] = {
> +		CONV_TYPE_MAPPING,   0,    0, 0,     1,    1,
> +		},
> +	[CPCAP_ADC_BPLUS_AD4] = {
> +		CONV_TYPE_DIRECT,    0, 2400, 0,  2300, 1023,
> +	},
> +	[CPCAP_ADC_CHG_ISENSE] = {
> +		CONV_TYPE_DIRECT, -512,    2, 0,  5000, 1023,
> +	},
> +	[CPCAP_ADC_BATTI_ADC] = {
> +		CONV_TYPE_DIRECT, -512,    2, 0,  5000, 1023,
> +	},
> +	[CPCAP_ADC_USB_ID] = {
> +		CONV_TYPE_NONE,      0,    0, 0,     1,    1,
> +	},
> +};
> +
> +/* Conversion table for bank1 */
> +static struct cpcap_adc_conversion_tbl bank1_conversion[CPCAP_ADC_BANK1_NUM] = {
> +	[CPCAP_ADC_AD8] =          {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_AD9] =          {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_LICELL] =       {CONV_TYPE_DIRECT, 0,  0,  0, 3400, 1023},
> +	[CPCAP_ADC_HV_BATTP] =     {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_TSX1_AD12] =    {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_TSX2_AD13] =    {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_TSY1_AD14] =    {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +	[CPCAP_ADC_TSY2_AD15] =    {CONV_TYPE_NONE,   0,  0,  0,    1,    1},
> +};
> +
> +/*
> + * Temperature lookup table of register values to milliCelcius.
> + * REVISIT: Check the duplicate 0x3ff entry in a freezer
:) Best comment I've seen in a driver for a while!
> + */
> +static const int temp_map[MAX_TEMP_LVL][2] = {
> +	{ 0x03ff, -40000 },
> +	{ 0x03ff, -35000 },
> +	{ 0x03ef, -30000 },
> +	{ 0x03b2, -25000 },
> +	{ 0x036c, -20000 },
> +	{ 0x0320, -15000 },
> +	{ 0x02d0, -10000 },
> +	{ 0x027f, -5000 },
> +	{ 0x022f, 0 },
> +	{ 0x01e4, 5000 },
> +	{ 0x019f, 10000 },
> +	{ 0x0161, 15000 },
> +	{ 0x012b, 20000 },
> +	{ 0x00fc, 25000 },
> +	{ 0x00d4, 30000 },
> +	{ 0x00b2, 35000 },
> +	{ 0x0095, 40000 },
> +	{ 0x007d, 45000 },
> +	{ 0x0069, 50000 },
> +	{ 0x0059, 55000 },
> +	{ 0x004b, 60000 },
> +	{ 0x003f, 65000 },
> +	{ 0x0036, 70000 },
> +	{ 0x002e, 75000 },
> +	{ 0x0027, 80000 },
> +	{ 0x0022, 85000 },
> +	{ 0x001d, 90000 },
> +};
> +
> +static irqreturn_t cpcap_adc_irq_thread(int irq, void *data)
> +{
> +	struct iio_dev *indio_dev = data;
> +	struct cpcap_adc *ddata = iio_priv(indio_dev);
> +	int error;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ADTRIG_DIS,
> +				   CPCAP_BIT_ADTRIG_DIS);
> +	if (error)
> +		return IRQ_NONE;
> +
> +	ddata->done = true;
> +	wake_up_interruptible(&ddata->wq_data_avail);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +#define CPCAP_CHAN(_type, _index, _address, _datasheet_name) {	\
> +	.type = (_type), \
> +	.address = (_address), \
> +	.indexed = 1, \
> +	.channel = (_index), \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> +			      BIT(IIO_CHAN_INFO_SCALE), \
> +	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> +				   BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
> +	.scan_index = (_index), \
> +	.scan_type = { \
> +		.sign = 'u', \
> +		.realbits = 10, \
> +		.storagebits = 16, \
> +		.endianness = IIO_CPU, \
> +	}, \
> +	.datasheet_name = (_datasheet_name), \
> +}
> +
> +/*
> + * The datasheet names are from Motorola mapphone Linux kernel except
> + * for the last two which might be uncalibrated charge voltage and
> + * current.
> + */
> +static const struct iio_chan_spec cpcap_adc_channels[] = {
> +	CPCAP_CHAN(IIO_TEMP, 0, CPCAP_REG_ADCD0, "battdetb"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 1, CPCAP_REG_ADCD1, "battp"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 2, CPCAP_REG_ADCD2, "vbus"),
> +	CPCAP_CHAN(IIO_TEMP, 3, CPCAP_REG_ADCD3, "ad3"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 4, CPCAP_REG_ADCD4, "ad4"),
> +	CPCAP_CHAN(IIO_CURRENT, 5, CPCAP_REG_ADCD5, "chg_isense"),
> +	CPCAP_CHAN(IIO_CURRENT, 6, CPCAP_REG_ADCD6, "batti"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 7, CPCAP_REG_ADCD7, "usb_id"),
> +
> +	CPCAP_CHAN(IIO_CURRENT, 8, CPCAP_REG_ADCD0, "ad8"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 9, CPCAP_REG_ADCD1, "ad9"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 10, CPCAP_REG_ADCD2, "licell"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 11, CPCAP_REG_ADCD3, "hv_battp"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 12, CPCAP_REG_ADCD4, "tsx1_ad12"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 13, CPCAP_REG_ADCD5, "tsx2_ad13"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 14, CPCAP_REG_ADCD6, "tsy1_ad14"),
> +	CPCAP_CHAN(IIO_VOLTAGE, 15, CPCAP_REG_ADCD7, "tsy2_ad15"),
Touch screen kicking around on here as well?  Or am I reading too much into
the names?
> +
> +	/* There are two registers with multiplexed functionality */
> +	CPCAP_CHAN(IIO_VOLTAGE, 16, CPCAP_REG_ADCD0, "chg_vsense"),
> +	CPCAP_CHAN(IIO_CURRENT, 17, CPCAP_REG_ADCD1, "batti2"),
> +};
> +
> +/* ADC calibration functions */
> +
> +static void cpcap_adc_setup_calibrate(struct cpcap_adc *ddata,
> +				      enum cpcap_adc_bank0 chan)
> +{
> +	unsigned int value = 0;
> +	unsigned long timeout = jiffies + msecs_to_jiffies(3000);
> +	int error;
> +
> +	if ((chan != CPCAP_ADC_CHG_ISENSE) &&
> +	    (chan != CPCAP_ADC_BATTI_ADC))
> +		return;
> +
> +	value |= CPCAP_BIT_CAL_MODE | CPCAP_BIT_RAND0;
> +	value |= ((chan << 4) &
> +		  (CPCAP_BIT_ADA2 | CPCAP_BIT_ADA1 | CPCAP_BIT_ADA0));
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC1,
> +				   CPCAP_BIT_CAL_MODE | CPCAP_BIT_ATOX |
> +				   CPCAP_BIT_ATO3 | CPCAP_BIT_ATO2 |
> +				   CPCAP_BIT_ATO1 | CPCAP_BIT_ATO0 |
> +				   CPCAP_BIT_ADA2 | CPCAP_BIT_ADA1 |
> +				   CPCAP_BIT_ADA0 | CPCAP_BIT_AD_SEL1 |
> +				   CPCAP_BIT_RAND1 | CPCAP_BIT_RAND0,
> +				   value);
> +	if (error)
> +		return;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ATOX_PS_FACTOR |
> +				   CPCAP_BIT_ADC_PS_FACTOR1 |
> +				   CPCAP_BIT_ADC_PS_FACTOR0,
> +				   0);
> +	if (error)
> +		return;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ADTRIG_DIS,
> +				   CPCAP_BIT_ADTRIG_DIS);
> +	if (error)
> +		return;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ASC,
> +				   CPCAP_BIT_ASC);
> +	if (error)
> +		return;
> +
> +	do {
> +		schedule_timeout_uninterruptible(1);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCC2, &value);
> +		if (error)
> +			return;
> +	} while ((value & CPCAP_BIT_ASC) && time_before(jiffies, timeout));
> +
> +	if (value & CPCAP_BIT_ASC)
> +		dev_err(ddata->dev,
> +			"Timeout waiting for calibration to complete\n");
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC1,
> +				   CPCAP_BIT_CAL_MODE, 0);
> +	if (error)
> +		return;
> +}
> +
> +static int cpcap_adc_calibrate(struct cpcap_adc *ddata)
> +{
> +	unsigned int cal_data[2];
> +	unsigned short cal_data_diff;
> +	int i, error;
> +
> +	i = 0;
> +	do {
> +		cal_data[0]  = 0;
> +		cal_data[1]  = 0;
> +		cal_data_diff = 0;
> +		cpcap_adc_setup_calibrate(ddata, CPCAP_ADC_CHG_ISENSE);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL1, &cal_data[0]);
> +		if (error)
> +			return error;
> +		cpcap_adc_setup_calibrate(ddata, CPCAP_ADC_CHG_ISENSE);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL1, &cal_data[1]);
> +		if (error)
> +			return error;
> +
> +		if (cal_data[0] > cal_data[1])
> +			cal_data_diff = cal_data[0] - cal_data[1];
> +		else
> +			cal_data_diff = cal_data[1] - cal_data[0];
> +
> +		if (((cal_data[1] >= ST_ADC_CAL_CHRGI_LOWER_THRESHOLD) &&
> +		     (cal_data[1] <= ST_ADC_CAL_CHRGI_UPPER_THRESHOLD) &&
> +		     (cal_data_diff <= ST_ADC_CALIBRATE_DIFF_THRESHOLD)) ||
> +		    (ddata->vendor == CPCAP_VENDOR_TI)) {
> +			bank0_conversion[CPCAP_ADC_CHG_ISENSE].cal_offset =
> +				((short)cal_data[1] * -1) + 512;
> +			dev_info(ddata->dev,
> +				 "cpcap_adc_probe: CHRGI Cal complete!\n");
> +			break;
> +		}
> +
> +		msleep(5);
> +		i++;
> +	} while (i > 5);
> +
> +	i = 0;
> +	do {
> +		cal_data[0]  = 0;
> +		cal_data[1]  = 0;
> +		cal_data_diff = 0;
> +		cpcap_adc_setup_calibrate(ddata, CPCAP_ADC_BATTI_ADC);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL2, &cal_data[0]);
> +		if (error)
> +			return error;
> +		cpcap_adc_setup_calibrate(ddata, CPCAP_ADC_BATTI_ADC);
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL2, &cal_data[1]);
> +		if (error)
> +			return error;
> +
> +		if (cal_data[0] > cal_data[1])
> +			cal_data_diff = cal_data[0] - cal_data[1];
> +		else
> +			cal_data_diff = cal_data[1] - cal_data[0];
> +
> +		if (((cal_data[1] >= ST_ADC_CAL_BATTI_LOWER_THRESHOLD) &&
> +		     (cal_data[1] <= ST_ADC_CAL_BATTI_UPPER_THRESHOLD) &&
> +		     (cal_data_diff <= ST_ADC_CALIBRATE_DIFF_THRESHOLD)) ||
> +		    (ddata->vendor == CPCAP_VENDOR_TI)) {
> +			bank0_conversion[CPCAP_ADC_BATTI_ADC].cal_offset =
> +				((short)cal_data[1] * -1) + 512;
> +			dev_info(ddata->dev,
> +				 "cpcap_adc_probe: BATTI Cal complete!\n");
> +			break;
> +		}
> +
> +		msleep(5);
> +		i++;
> +	} while (i > 5);
> +
> +	return 0;
> +}
> +
> +/* ADC setup, read and scale functions */
> +
> +static void cpcap_adc_setup_bank(struct cpcap_adc *ddata,
> +				 enum cpcap_adc_type type,
> +				 enum cpcap_adc_timing timing)
> +{
> +	const struct cpcap_adc_ato *ato = ddata->ato;
> +	unsigned short value1 = 0;
> +	unsigned short value2 = 0;
> +	int error;
> +
> +	if (!ato)
> +		return;
> +
> +	if (type == CPCAP_ADC_TYPE_BANK_1)
> +		value1 |= CPCAP_BIT_AD_SEL1;
> +	else if (type == CPCAP_ADC_TYPE_BATT_PI)
> +		value1 |= CPCAP_BIT_RAND1;
> +
> +	switch (timing) {
> +	case CPCAP_ADC_TIMING_IN:
> +		value1 |= ato->ato_in;
> +		value1 |= ato->atox_in;
> +		value2 |= ato->adc_ps_factor_in;
> +		value2 |= ato->atox_ps_factor_in;
> +		break;
> +
> +	case CPCAP_ADC_TIMING_OUT:
> +		value1 |= ato->ato_out;
> +		value1 |= ato->atox_out;
> +		value2 |= ato->adc_ps_factor_out;
> +		value2 |= ato->atox_ps_factor_out;
> +		break;
> +
> +	case CPCAP_ADC_TIMING_IMM:
> +	default:
> +		break;
> +	}
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC1,
> +				   CPCAP_BIT_CAL_MODE | CPCAP_BIT_ATOX |
> +				   CPCAP_BIT_ATO3 | CPCAP_BIT_ATO2 |
> +				   CPCAP_BIT_ATO1 | CPCAP_BIT_ATO0 |
> +				   CPCAP_BIT_ADA2 | CPCAP_BIT_ADA1 |
> +				   CPCAP_BIT_ADA0 | CPCAP_BIT_AD_SEL1 |
> +				   CPCAP_BIT_RAND1 | CPCAP_BIT_RAND0,
> +				   value1);
> +	if (error)
> +		return;
> +
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ATOX_PS_FACTOR |
> +				   CPCAP_BIT_ADC_PS_FACTOR1 |
> +				   CPCAP_BIT_ADC_PS_FACTOR0,
> +				   value2);
> +	if (error)
> +		return;
> +
> +	if (timing == CPCAP_ADC_TIMING_IMM) {
> +		error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +					   CPCAP_BIT_ADTRIG_DIS,
> +					   CPCAP_BIT_ADTRIG_DIS);
> +		if (error)
> +			return;
> +
> +		error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +					   CPCAP_BIT_ASC,
> +					   CPCAP_BIT_ASC);
> +		if (error)
> +			return;
> +	} else {
> +		error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +					   CPCAP_BIT_ADTRIG_ONESHOT,
> +					   CPCAP_BIT_ADTRIG_ONESHOT);
> +		if (error)
> +			return;
> +
> +		error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +					   CPCAP_BIT_ADTRIG_DIS, 0);
> +		if (error)
> +			return;
> +	}
> +}
> +
> +/*
> + * Occasionally the ADC does not seem to start and there will be no
> + * interrupt. Let's re-init interrupt to prevent the ADC from hanging
> + * for the next request. It is unclear why this happens, but the next
> + * request will usually work after doing this.
> + */
> +static void cpcap_adc_quirk_reset_lost_irq(struct cpcap_adc *ddata)
> +{
> +	int error;
> +
> +	dev_info(ddata->dev, "lost ADC irq, attempting to reinit\n");
> +	disable_irq(ddata->irq);
> +	error = regmap_update_bits(ddata->reg, CPCAP_REG_ADCC2,
> +				   CPCAP_BIT_ADTRIG_DIS,
> +				   CPCAP_BIT_ADTRIG_DIS);
> +	if (error)
> +		dev_warn(ddata->dev, "%s reset failed: %i\n",
> +			 __func__, error);
> +	enable_irq(ddata->irq);
> +}
> +
> +static int cpcap_adc_start_bank(struct cpcap_adc *ddata,
> +				struct cpcap_adc_request *req)
> +{
> +	int i, error;
> +
> +	req->timing = CPCAP_ADC_TIMING_IMM;
> +	ddata->done = false;
> +
> +	for (i = 0; i < 5; i++) {
> +		cpcap_adc_setup_bank(ddata, req->type, req->timing);
> +		error = wait_event_interruptible_timeout(ddata->wq_data_avail,
> +							 ddata->done,
> +							 msecs_to_jiffies(50));
> +		if (error >= 0)
> +			return 0;
> +
> +		if (error == 0) {
> +			cpcap_adc_quirk_reset_lost_irq(ddata);
> +			error = -ETIMEDOUT;
> +			continue;
> +		}
> +
> +		if (error < 0)
> +			return error;
> +	}
> +
> +	return error;
> +}
> +
> +static void cpcap_adc_phase(struct cpcap_adc_request *req, int index)
> +{
> +	struct cpcap_adc_conversion_tbl *conv_tbl = bank0_conversion;
> +	struct cpcap_adc_phasing_tbl *phase_tbl = bank0_phasing;
> +	int tbl_index = index;
> +
> +	if (req->type == CPCAP_ADC_TYPE_BANK_1) {
> +		conv_tbl = bank1_conversion;
> +		phase_tbl = bank1_phasing;
> +	}
> +
> +	if (req->type == CPCAP_ADC_TYPE_BATT_PI)
> +		tbl_index = (tbl_index % 2) ? CPCAP_ADC_BATTI_ADC :
> +			CPCAP_ADC_BATTP;
> +
> +	if (((req->type == CPCAP_ADC_TYPE_BANK_0) ||
> +	     (req->type == CPCAP_ADC_TYPE_BATT_PI)) &&
> +	    (tbl_index == CPCAP_ADC_BATTP)) {
> +		req->result[index] -= phase_tbl[tbl_index].offset;
> +		req->result[index] -= FOUR_POINT_TWO_ADC;
> +		req->result[index] *= phase_tbl[tbl_index].multiplier;
> +		if (phase_tbl[tbl_index].divider == 0)
> +			return;
> +		req->result[index] /= phase_tbl[tbl_index].divider;
> +		req->result[index] += FOUR_POINT_TWO_ADC;
> +	} else {
> +		req->result[index] += conv_tbl[tbl_index].cal_offset;
> +		req->result[index] += conv_tbl[tbl_index].align_offset;
> +		req->result[index] *= phase_tbl[tbl_index].multiplier;
> +		if (phase_tbl[tbl_index].divider == 0)
> +			return;
> +		req->result[index] /= phase_tbl[tbl_index].divider;
> +		req->result[index] += phase_tbl[tbl_index].offset;
> +	}
> +
> +	if (req->result[index] < phase_tbl[tbl_index].min)
> +		req->result[index] = phase_tbl[tbl_index].min;
> +	else if (req->result[index] > phase_tbl[tbl_index].max)
> +		req->result[index] = phase_tbl[tbl_index].max;
> +}
> +
> +/* Looks up temperatures in a table and calculates averages if needed */
> +static unsigned short cpcap_adc_table_to_millicelcius(unsigned short value)
Oh goody. Nice and nonlinear ;)  Defintely looking at _processed channels
here...
> +{
> +	int i;
> +	int result = 0, alpha = 0;
> +
> +	if (value <= temp_map[MAX_TEMP_LVL - 1][0])
> +		return temp_map[MAX_TEMP_LVL - 1][1];
> +
> +	if (value >= temp_map[0][0])
> +		return temp_map[0][1];
> +
> +	for (i = 0; i < MAX_TEMP_LVL - 1; i++) {
> +		if ((value <= temp_map[i][0]) &&
> +		    (value >= temp_map[i + 1][0])) {
> +			if (value == temp_map[i][0]) {
> +				result = temp_map[i][1];
> +			} else if (value == temp_map[i + 1][0]) {
> +				result = temp_map[i + 1][1];
> +			} else {
> +				alpha = ((value - temp_map[i][0]) * 1000) /
> +					(temp_map[i + 1][0] - temp_map[i][0]);
> +
> +				result = temp_map[i][1] +
> +					((alpha * (temp_map[i + 1][1] -
> +						 temp_map[i][1])) / 1000);
> +			}
> +			break;
> +		}
> +	}
> +
> +	return result;
> +}
> +
> +static void cpcap_adc_convert(struct cpcap_adc_request *req, int index)
> +{
> +	struct cpcap_adc_conversion_tbl *conv_tbl = bank0_conversion;
> +	int tbl_index = index;
> +
> +	if (req->type == CPCAP_ADC_TYPE_BANK_1)
> +		conv_tbl = bank1_conversion;
Easier code flow perhaps to have this as a switch?
Then it would be immediately obvious for the BATT_PPI case that conv_tbl
is set to bank0_conversion (which seems odd ;)  It does rather feel
like we could simplify this by using the chan->address to hold an index
into a table with each channels setup laid out more clearly.
Maybe not though - I haven't actually tried to unwind it!
> +
> +	if (req->type == CPCAP_ADC_TYPE_BATT_PI)
> +		tbl_index = (tbl_index % 2) ? CPCAP_ADC_BATTI_ADC :
> +			    CPCAP_ADC_BATTP;
> +
> +	if (conv_tbl[tbl_index].conv_type == CONV_TYPE_DIRECT) {
> +		req->result[index] *= conv_tbl[tbl_index].multiplier;
> +		if (conv_tbl[tbl_index].divider == 0)
> +			return;
> +		req->result[index] /= conv_tbl[tbl_index].divider;
> +		req->result[index] += conv_tbl[tbl_index].conv_offset;
> +	} else if (conv_tbl[tbl_index].conv_type == CONV_TYPE_MAPPING)
> +		req->result[index] =
> +			cpcap_adc_table_to_millicelcius(req->result[tbl_index]);
> +}
> +
> +static int cpcap_adc_read_bank_scaled(struct cpcap_adc *ddata,
> +				      struct cpcap_adc_request *req,
> +				      const unsigned long channel_mask)
I think you only ever call this with a single bit set in the channel_mask.
Leads to some obvious simplifications....
> +{
> +	unsigned int i;
> +	int cal_data, error;
> +
> +	if (ddata->vendor == CPCAP_VENDOR_TI) {
> +		cal_data = 0;
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL1, &cal_data);
Either cal_data is the wrong length for the regmap read or you shouldn't
need to zero it...
> +		if (error)
> +			return error;
> +		bank0_conversion[CPCAP_ADC_CHG_ISENSE].cal_offset =
> +			((short)cal_data * -1) + 512;
> +	}
> +
Put both of these in the same if?
> +	if (ddata->vendor == CPCAP_VENDOR_TI) {
> +		cal_data = 0;
> +		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL2, &cal_data);
> +		if (error)
> +			return error;
> +		bank0_conversion[CPCAP_ADC_BATTI_ADC].cal_offset =
> +			((short)cal_data * -1) + 512;
> +	}
> +
> +	for_each_set_bit(i, &channel_mask, 8) {
> +		int addr = CPCAP_REG_ADCD0 + i * 4;
> +
> +		error = regmap_read(ddata->reg, addr, &req->result[i]);
> +		if (error)
> +			return error;
> +
> +		req->result[i] &= 0x3ff;
> +		cpcap_adc_phase(req, i);
> +		cpcap_adc_convert(req, i);
> +	}
> +
> +	return 0;
> +}
> +
> +static int cpcap_adc_read(struct iio_dev *indio_dev,
> +			  struct iio_chan_spec const *chan,
> +			  int *val, int *val2, long mask)
> +{
> +	struct cpcap_adc *ddata = iio_priv(indio_dev);
> +	struct cpcap_adc_request req;
> +	int index, error;
> +
> +	if (chan->channel < 8) {
> +		index = chan->channel;
> +		req.type = CPCAP_ADC_TYPE_BANK_0;
> +	} else if (chan->channel < 16) {
> +		index = chan->channel - 8;
> +		req.type = CPCAP_ADC_TYPE_BANK_1;
> +	} else if (chan->channel < 18) {
> +		index = chan->channel - 16;
> +		req.type = CPCAP_ADC_TYPE_BATT_PI;
> +	} else {
> +		return -EINVAL;
> +	}
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&ddata->lock);
> +		error = cpcap_adc_start_bank(ddata, &req);
> +		if (error)
> +			goto err_unlock;
> +		error = regmap_read(ddata->reg, chan->address, val);
> +		if (error)
> +			goto err_unlock;
> +		mutex_unlock(&ddata->lock);
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		mutex_lock(&ddata->lock);
> +		error = cpcap_adc_start_bank(ddata, &req);
> +		if (error)
> +			goto err_unlock;
> +		error = cpcap_adc_read_bank_scaled(ddata, &req, BIT(index));
> +		if (error)
> +			goto err_unlock;
> +		mutex_unlock(&ddata->lock);
> +		*val = req.result[index];

This would come in the seriously unusual category if the scale is integer...
Could be I suppose, but seems unlikely ;)
Note that value in mV should be raw_value * scale.

I'd guess these are what we term _processed channels, i.e. already in mV?
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return IIO_VAL_INT;
> +
> +err_unlock:
> +	mutex_unlock(&ddata->lock);
> +	dev_err(ddata->dev, "error reading ADC: %i\n", error);
> +
> +	return error;
> +}
> +
> +static const struct iio_info cpcap_adc_info = {
> +	.read_raw = &cpcap_adc_read,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +/*
> + * Configuration for Motorola mapphone series such as droid 4.
> + * Copied from the Motorola mapphone kernel tree.
> + */
> +static const struct cpcap_adc_ato mapphone_adc = {
> +	.ato_in = 0x0480,
> +	.atox_in = 0,
> +	.adc_ps_factor_in = 0x0200,
> +	.atox_ps_factor_in = 0,
> +	.ato_out = 0,
> +	.atox_out = 0,
> +	.adc_ps_factor_out = 0,
> +	.atox_ps_factor_out = 0,
> +};
> +
> +static const struct of_device_id cpcap_adc_id_table[] = {
> +	{
> +		.compatible = "motorola,cpcap-adc",
> +	},
> +	{
> +		.compatible = "motorola,mapphone-cpcap-adc",
> +		.data = &mapphone_adc,
> +	},
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, cpcap_adc_id_table);
> +
> +static int cpcap_adc_probe(struct platform_device *pdev)
> +{
> +	const struct of_device_id *match;
> +	struct cpcap_adc *ddata;
> +	struct iio_dev *indio_dev;
> +	struct iio_buffer *buf;
> +	int error;
> +
> +	match = of_match_device(of_match_ptr(cpcap_adc_id_table),
> +				&pdev->dev);
> +	if (!match)
> +		return -EINVAL;
> +
> +	if (!match->data) {
> +		dev_err(&pdev->dev, "no configuration data found\n");
> +
> +		return -ENODEV;
> +	}
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*ddata));
> +	if (!indio_dev) {
> +		dev_err(&pdev->dev, "failed to allocate iio device\n");
> +
> +		return -ENOMEM;
> +	}
> +	ddata = iio_priv(indio_dev);
> +	ddata->ato = match->data;
> +	ddata->dev = &pdev->dev;
> +
> +	mutex_init(&ddata->lock);
> +	init_waitqueue_head(&ddata->wq_data_avail);
> +
> +	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->dev.of_node = pdev->dev.of_node;
> +	indio_dev->channels = cpcap_adc_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(cpcap_adc_channels);
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->info = &cpcap_adc_info;
> +
> +	ddata->reg = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!ddata->reg)
> +		return -ENODEV;
> +
> +	error = cpcap_get_vendor(ddata->dev, ddata->reg, &ddata->vendor);
> +	if (error)
> +		return error;
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	ddata->irq = platform_get_irq_byname(pdev, "adcdone");
> +	if (!ddata->irq)
> +		return -ENODEV;
> +
> +	error = devm_request_threaded_irq(&pdev->dev, ddata->irq, NULL,
> +					  cpcap_adc_irq_thread, IRQ_NONE,
> +					  "cpcap-adc", indio_dev);
IRQ_NONE?  Novel. Definitely needs an explanatory comment.
> +	if (error) {
> +		dev_err(&pdev->dev, "could not get irq: %i\n",
> +			error);
> +
> +		return error;
> +	}
> +
> +	error = cpcap_adc_calibrate(ddata);
> +	if (error)
> +		return error;
> +
> +	buf = devm_iio_kfifo_allocate(&indio_dev->dev);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	iio_device_attach_buffer(indio_dev, buf);
Why?  Nothing is ever pushed ot the buffer that I can see.
> +
> +	dev_info(&pdev->dev, "CPCAP ADC device probed\n");
> +
> +	return iio_device_register(indio_dev);
> +}
> +
> +static int cpcap_adc_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +
> +	iio_device_unregister(indio_dev);
If all you have is unregister in remove, it's a fairly sure sign
you could have used devm_iio_device_register and dropped the remove
entirely.

> +
> +	return 0;
> +}
> +
> +static struct platform_driver cpcap_adc_driver = {
> +	.driver = {
> +		.name = "cpcap_adc",
> +		.of_match_table = of_match_ptr(cpcap_adc_id_table),
> +	},
> +	.probe = cpcap_adc_probe,
> +	.remove = cpcap_adc_remove,
> +};
> +
> +module_platform_driver(cpcap_adc_driver);
> +
> +MODULE_ALIAS("platform:cpcap_adc");
> +MODULE_DESCRIPTION("CPCAP ADC driver");
> +MODULE_AUTHOR("Motorola and Tony Lindgren <tony@atomide.com");
> +MODULE_LICENSE("GPL v2");
> 

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* Jonathan Cameron <jic23@kernel.org> [170319 10:08]:
> On 17/03/17 01:43, Tony Lindgren wrote:
> > On Motorola phones like droid 4 there is a custom CPCAP PMIC. This PMIC
> > has ADCs that are used for battery charging and USB PHY VBUS and ID pin
> > detection.
> > 
> > Unfortunately the only documentation for this ADC seems to be the
> > Motorola mapphone Linux kernel tree. I have tested that reading raw and
> > scaled values works, but I have not used the timed sampling that the ADC
> > seems to support.
> Any link? I'm curious to see just how 'interesting' this was...

Well the Motorola kernel has the CPCAP PMIC registers quite nicely
documented. I mostly use the "STS-Dev-Team/kernel_mapphone_kexec"
git tree as a reference as that has the original Motorola patch
imported into a git tree. Below are few links to selected files
for fun reading:

https://github.com/STS-Dev-Team/kernel_mapphone_kexec
https://github.com/STS-Dev-Team/kernel_mapphone_kexec/blob/cm-10.1/drivers/mfd/cpcap-adc.c
https://github.com/STS-Dev-Team/kernel_mapphone_kexec/blob/cm-10.1/include/linux/spi/cpcap-regbits.h
https://github.com/STS-Dev-Team/kernel_mapphone_kexec/blob/cm-10.1/include/linux/spi/cpcap.h

> You are a brave person...

Well n950 is too hard to replace.. And n900 is a bit memory limited..
And there are tons of used droid 4 available for about $35 or so :)

> > +/*
> > + * Temperature lookup table of register values to milliCelcius.
> > + * REVISIT: Check the duplicate 0x3ff entry in a freezer
> :) Best comment I've seen in a driver for a while!

:)

> > +static const struct iio_chan_spec cpcap_adc_channels[] = {
> > +	CPCAP_CHAN(IIO_TEMP, 0, CPCAP_REG_ADCD0, "battdetb"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 1, CPCAP_REG_ADCD1, "battp"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 2, CPCAP_REG_ADCD2, "vbus"),
> > +	CPCAP_CHAN(IIO_TEMP, 3, CPCAP_REG_ADCD3, "ad3"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 4, CPCAP_REG_ADCD4, "ad4"),
> > +	CPCAP_CHAN(IIO_CURRENT, 5, CPCAP_REG_ADCD5, "chg_isense"),
> > +	CPCAP_CHAN(IIO_CURRENT, 6, CPCAP_REG_ADCD6, "batti"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 7, CPCAP_REG_ADCD7, "usb_id"),
> > +
> > +	CPCAP_CHAN(IIO_CURRENT, 8, CPCAP_REG_ADCD0, "ad8"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 9, CPCAP_REG_ADCD1, "ad9"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 10, CPCAP_REG_ADCD2, "licell"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 11, CPCAP_REG_ADCD3, "hv_battp"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 12, CPCAP_REG_ADCD4, "tsx1_ad12"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 13, CPCAP_REG_ADCD5, "tsx2_ad13"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 14, CPCAP_REG_ADCD6, "tsy1_ad14"),
> > +	CPCAP_CHAN(IIO_VOLTAGE, 15, CPCAP_REG_ADCD7, "tsy2_ad15"),
> Touch screen kicking around on here as well?  Or am I reading too much into
> the names?

Yeah so it seems. These do not seem to be wired to anything in
droid 4, but the Motorola kernel supports a whole family of
devices, so it was probably used for touch screen on some at some
point.

> > +		*val = req.result[index];
> 
> This would come in the seriously unusual category if the scale is integer...
> Could be I suppose, but seems unlikely ;)
> Note that value in mV should be raw_value * scale.
> 
> I'd guess these are what we term _processed channels, i.e. already in mV?

Oh OK, thanks I'll check, yeah it's already in mV.

> If all you have is unregister in remove, it's a fairly sure sign
> you could have used devm_iio_device_register and dropped the remove
> entirely.

Sure. Will also look at the other comments and repost, thanks
for the review.

Regards,

Tony
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