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 Lindgren <tony@atomide.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/adc/cpcap-adc.txt

+Motorola CPCAP PMIC ADC binding
+
+Required properties:
+- compatible: Should be "motorola,cpcap-adc" or "motorola,mapphone-cpcap-adc"
+- interrupt-parent: The interrupt controller
+- 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";
+	interrupt-parent = <&cpcap>;
+	interrupts = <8 IRQ_TYPE_NONE>;
+	interrupt-names = "adcdone";
+	#io-channel-cells = <1>;
+};

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

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

drivers/iio/adc/cpcap-adc.c

+/*
+ * Copyright (C) 2017 Tony Lindgren <tony@atomide.com>
+ *
+ * Rewritten for Linux IIO framework with some code 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)
+#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 bank1 */
+#define CPCAP_BIT_RAND1			BIT(2)	/* Set for channel 16 & 17 */
+#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)
+#define CPCAP_BIT_ADC_PS_FACTOR1	BIT(10)
+#define CPCAP_BIT_ADC_PS_FACTOR0	BIT(9)
+#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 CPCAP_MAX_TEMP_LVL		27
+#define CPCAP_FOUR_POINT_TWO_ADC	801
+#define ST_ADC_CAL_CHRGI_HIGH_THRESHOLD	530
+#define ST_ADC_CAL_CHRGI_LOW_THRESHOLD	494
+#define ST_ADC_CAL_BATTI_HIGH_THRESHOLD	530
+#define ST_ADC_CAL_BATTI_LOW_THRESHOLD	494
+#define ST_ADC_CALIBRATE_DIFF_THRESHOLD	3
+
+#define CPCAP_ADC_MAX_RETRIES		5	/* Calibration and quirk */
+
+/**
+ * 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_channel - cpcap adc channels
+ */
+enum cpcap_adc_channel {
+	/* Bank0 channels */
+	CPCAP_ADC_AD0_BATTDETB,	/* Battery detection */
+	CPCAP_ADC_BATTP,	/* Battery voltage */
+	CPCAP_ADC_VBUS,		/* USB VBUS voltage */
+	CPCAP_ADC_AD3,		/* Battery temperature when charging */
+	CPCAP_ADC_BPLUS_AD4,	/* Another battery or system voltage */
+	CPCAP_ADC_CHG_ISENSE,	/* Calibrated charge current */
+	CPCAP_ADC_BATTI,	/* Calibrated system current */
+	CPCAP_ADC_USB_ID,	/* USB OTG ID, unused on droid 4? */
+
+	/* Bank1 channels */
+	CPCAP_ADC_AD8,		/* Seems unused */
+	CPCAP_ADC_AD9,		/* Seems unused */
+	CPCAP_ADC_LICELL,	/* Maybe system voltage? Always 3V */
+	CPCAP_ADC_HV_BATTP,	/* Another battery detection? */
+	CPCAP_ADC_TSX1_AD12,	/* Seems unused, for touchscreen? */
+	CPCAP_ADC_TSX2_AD13,	/* Seems unused, for touchscreen? */
+	CPCAP_ADC_TSY1_AD14,	/* Seems unused, for touchscreen? */
+	CPCAP_ADC_TSY2_AD15,	/* Seems unused, for touchscreen? */
+
+	/* Remuxed channels using bank0 entries */
+	CPCAP_ADC_BATTP_PI16,	/* Alternative mux mode for BATTP */
+	CPCAP_ADC_BATTI_PI17,	/* Alternative mux mode for BATTI */
+
+	CPCAP_ADC_CHANNEL_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,
+};
+
+/**
+ * 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;
+};
+
+/**
+ * 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 iio_chan_info_enum conv_type;
+	int align_offset;
+	int conv_offset;
+	int cal_offset;
+	int multiplier;
+	int divider;
+};
+
+/**
+ * struct cpcap_adc_request - cpcap adc request
+ * @channel: request channel
+ * @phase_tbl: channel phasing table
+ * @conv_tbl: channel conversion table
+ * @bank_index: channel index within the bank
+ * @timing: timing settings
+ * @result: result
+ */
+struct cpcap_adc_request {
+	int channel;
+	const struct cpcap_adc_phasing_tbl *phase_tbl;
+	const struct cpcap_adc_conversion_tbl *conv_tbl;
+	int bank_index;
+	enum cpcap_adc_timing timing;
+	int result;
+};
+
+/* Phasing table for channels. Note that channels 16 & 17 use BATTP and BATTI */
+static const struct cpcap_adc_phasing_tbl bank_phasing[] = {
+	/* Bank0 */
+	[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] =        {0, 0x80, 0x80, -512,  511},
+	[CPCAP_ADC_USB_ID] =       {0, 0x80, 0x80,    0, 1023},
+
+	/* Bank1 */
+	[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 channels. Updated during init based on calibration.
+ * Here too channels 16 & 17 use BATTP and BATTI.
+ */
+static struct cpcap_adc_conversion_tbl bank_conversion[] = {
+	/* Bank0 */
+	[CPCAP_ADC_AD0_BATTDETB] = {
+		IIO_CHAN_INFO_PROCESSED,    0,    0, 0,     1,    1,
+	},
+	[CPCAP_ADC_BATTP] = {
+		IIO_CHAN_INFO_PROCESSED,    0, 2400, 0,  2300, 1023,
+	},
+	[CPCAP_ADC_VBUS] = {
+		IIO_CHAN_INFO_PROCESSED,    0,    0, 0, 10000, 1023,
+	},
+	[CPCAP_ADC_AD3] = {
+		IIO_CHAN_INFO_PROCESSED,    0,    0, 0,     1,    1,
+		},
+	[CPCAP_ADC_BPLUS_AD4] = {
+		IIO_CHAN_INFO_PROCESSED,    0, 2400, 0,  2300, 1023,
+	},
+	[CPCAP_ADC_CHG_ISENSE] = {
+		IIO_CHAN_INFO_PROCESSED, -512,    2, 0,  5000, 1023,
+	},
+	[CPCAP_ADC_BATTI] = {
+		IIO_CHAN_INFO_PROCESSED, -512,    2, 0,  5000, 1023,
+	},
+	[CPCAP_ADC_USB_ID] = {
+		IIO_CHAN_INFO_RAW,          0,    0, 0,     1,    1,
+	},
+
+	/* Bank1 */
+	[CPCAP_ADC_AD8] = {
+		IIO_CHAN_INFO_RAW,          0,    0, 0,     1,    1,
+	},
+	[CPCAP_ADC_AD9] = {
+		IIO_CHAN_INFO_RAW,          0,    0, 0,     1,    1,
+	},
+	[CPCAP_ADC_LICELL] = {
+		IIO_CHAN_INFO_PROCESSED,    0,    0, 0,  3400, 1023,
+	},
+	[CPCAP_ADC_HV_BATTP] = {
+		IIO_CHAN_INFO_RAW,          0,    0, 0,     1,    1,
+	},
+	[CPCAP_ADC_TSX1_AD12] = {
+		IIO_CHAN_INFO_RAW,          0,    0, 0,     1,    1,
+	},
+	[CPCAP_ADC_TSX2_AD13] = {
+		IIO_CHAN_INFO_RAW,          0,    0, 0,     1,    1,
+	},
+	[CPCAP_ADC_TSY1_AD14] = {
+		IIO_CHAN_INFO_RAW,          0,    0, 0,     1,    1,
+	},
+	[CPCAP_ADC_TSY2_AD15] = {
+		IIO_CHAN_INFO_RAW,          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[CPCAP_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 },
+};
+
+#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_PROCESSED), \
+	.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[] = {
+	/* Bank0 */
+	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"),
+
+	/* Bank1 */
+	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"),
+};
+
+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;
+}
+
+/* ADC calibration functions */
+static void cpcap_adc_setup_calibrate(struct cpcap_adc *ddata,
+				      enum cpcap_adc_channel 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))
+		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_one(struct cpcap_adc *ddata,
+				   int channel,
+				   u16 calibration_register,
+				   int lower_threshold,
+				   int upper_threshold)
+{
+	unsigned int calibration_data[2];
+	unsigned short cal_data_diff;
+	int i, error;
+
+	for (i = 0; i < CPCAP_ADC_MAX_RETRIES; i++) {
+		calibration_data[0]  = 0;
+		calibration_data[1]  = 0;
+		cal_data_diff = 0;
+		cpcap_adc_setup_calibrate(ddata, channel);
+		error = regmap_read(ddata->reg, calibration_register,
+				    &calibration_data[0]);
+		if (error)
+			return error;
+		cpcap_adc_setup_calibrate(ddata, channel);
+		error = regmap_read(ddata->reg, calibration_register,
+				    &calibration_data[1]);
+		if (error)
+			return error;
+
+		if (calibration_data[0] > calibration_data[1])
+			cal_data_diff =
+				calibration_data[0] - calibration_data[1];
+		else
+			cal_data_diff =
+				calibration_data[1] - calibration_data[0];
+
+		if (((calibration_data[1] >= lower_threshold) &&
+		     (calibration_data[1] <= upper_threshold) &&
+		     (cal_data_diff <= ST_ADC_CALIBRATE_DIFF_THRESHOLD)) ||
+		    (ddata->vendor == CPCAP_VENDOR_TI)) {
+			bank_conversion[channel].cal_offset =
+				((short)calibration_data[1] * -1) + 512;
+			dev_dbg(ddata->dev, "ch%i calibration complete: %i\n",
+				channel, bank_conversion[channel].cal_offset);
+			break;
+		}
+		usleep_range(5000, 10000);
+	}
+
+	return 0;
+}
+
+static int cpcap_adc_calibrate(struct cpcap_adc *ddata)
+{
+	int error;
+
+	error = cpcap_adc_calibrate_one(ddata, CPCAP_ADC_CHG_ISENSE,
+					CPCAP_REG_ADCAL1,
+					ST_ADC_CAL_CHRGI_LOW_THRESHOLD,
+					ST_ADC_CAL_CHRGI_HIGH_THRESHOLD);
+	if (error)
+		return error;
+
+	error = cpcap_adc_calibrate_one(ddata, CPCAP_ADC_BATTI,
+					CPCAP_REG_ADCAL2,
+					ST_ADC_CAL_BATTI_LOW_THRESHOLD,
+					ST_ADC_CAL_BATTI_HIGH_THRESHOLD);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+/* ADC setup, read and scale functions */
+static void cpcap_adc_setup_bank(struct cpcap_adc *ddata,
+				 struct cpcap_adc_request *req)
+{
+	const struct cpcap_adc_ato *ato = ddata->ato;
+	unsigned short value1 = 0;
+	unsigned short value2 = 0;
+	int error;
+
+	if (!ato)
+		return;
+
+	switch (req->channel) {
+	case CPCAP_ADC_AD8 ... CPCAP_ADC_TSY2_AD15:
+		value1 |= CPCAP_BIT_AD_SEL1;
+		break;
+	case CPCAP_ADC_BATTP_PI16 ... CPCAP_ADC_BATTI_PI17:
+		value1 |= CPCAP_BIT_RAND1;
+	default:
+		break;
+	}
+
+	switch (req->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 (req->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 < CPCAP_ADC_MAX_RETRIES; i++) {
+		cpcap_adc_setup_bank(ddata, req);
+		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)
+{
+	const struct cpcap_adc_conversion_tbl *conv_tbl = req->conv_tbl;
+	const struct cpcap_adc_phasing_tbl *phase_tbl = req->phase_tbl;
+	int index = req->channel;
+
+	/* Remuxed channels 16 and 17 use BATTP and BATTI entries */
+	switch (req->channel) {
+	case CPCAP_ADC_BATTP:
+	case CPCAP_ADC_BATTP_PI16:
+		index = req->bank_index;
+		req->result -= phase_tbl[index].offset;
+		req->result -= CPCAP_FOUR_POINT_TWO_ADC;
+		req->result *= phase_tbl[index].multiplier;
+		if (phase_tbl[index].divider == 0)
+			return;
+		req->result /= phase_tbl[index].divider;
+		req->result += CPCAP_FOUR_POINT_TWO_ADC;
+		break;
+	case CPCAP_ADC_BATTI_PI17:
+		index = req->bank_index;
+		/* fallthrough */
+	default:
+		req->result += conv_tbl[index].cal_offset;
+		req->result += conv_tbl[index].align_offset;
+		req->result *= phase_tbl[index].multiplier;
+		if (phase_tbl[index].divider == 0)
+			return;
+		req->result /= phase_tbl[index].divider;
+		req->result += phase_tbl[index].offset;
+		break;
+	}
+
+	if (req->result < phase_tbl[index].min)
+		req->result = phase_tbl[index].min;
+	else if (req->result > phase_tbl[index].max)
+		req->result = phase_tbl[index].max;
+}
+
+/* Looks up temperatures in a table and calculates averages if needed */
+static int cpcap_adc_table_to_millicelcius(unsigned short value)
+{
+	int i, result = 0, alpha;
+
+	if (value <= temp_map[CPCAP_MAX_TEMP_LVL - 1][0])
+		return temp_map[CPCAP_MAX_TEMP_LVL - 1][1];
+
+	if (value >= temp_map[0][0])
+		return temp_map[0][1];
+
+	for (i = 0; i < CPCAP_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)
+{
+	const struct cpcap_adc_conversion_tbl *conv_tbl = req->conv_tbl;
+	int index = req->channel;
+
+	/* Remuxed channels 16 and 17 use BATTP and BATTI entries */
+	switch (req->channel) {
+	case CPCAP_ADC_BATTP_PI16:
+		index = CPCAP_ADC_BATTP;
+		break;
+	case CPCAP_ADC_BATTI_PI17:
+		index = CPCAP_ADC_BATTI;
+		break;
+	default:
+		break;
+	}
+
+	/* No conversion for raw channels */
+	if (conv_tbl[index].conv_type == IIO_CHAN_INFO_RAW)
+		return;
+
+	/* Temperatures use a lookup table instead of conversion table */
+	if ((req->channel == CPCAP_ADC_AD0_BATTDETB) ||
+	    (req->channel == CPCAP_ADC_AD3)) {
+		req->result =
+			cpcap_adc_table_to_millicelcius(req->result);
+
+		return;
+	}
+
+	/* All processed channels use a conversion table */
+	req->result *= conv_tbl[index].multiplier;
+	if (conv_tbl[index].divider == 0)
+		return;
+	req->result /= conv_tbl[index].divider;
+	req->result += conv_tbl[index].conv_offset;
+}
+
+/*
+ * REVISIT: Check if timed sampling can use multiple channels at the
+ * same time. If not, replace channel_mask with just channel.
+ */
+static int cpcap_adc_read_bank_scaled(struct cpcap_adc *ddata,
+				      struct cpcap_adc_request *req)
+{
+	int calibration_data, error, addr;
+
+	if (ddata->vendor == CPCAP_VENDOR_TI) {
+		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL1,
+				    &calibration_data);
+		if (error)
+			return error;
+		bank_conversion[CPCAP_ADC_CHG_ISENSE].cal_offset =
+			((short)calibration_data * -1) + 512;
+
+		error = regmap_read(ddata->reg, CPCAP_REG_ADCAL2,
+				    &calibration_data);
+		if (error)
+			return error;
+		bank_conversion[CPCAP_ADC_BATTI].cal_offset =
+			((short)calibration_data * -1) + 512;
+	}
+
+	addr = CPCAP_REG_ADCD0 + req->bank_index * 4;
+
+	error = regmap_read(ddata->reg, addr, &req->result);
+	if (error)
+		return error;
+
+	req->result &= 0x3ff;
+	cpcap_adc_phase(req);
+	cpcap_adc_convert(req);
+
+	return 0;
+}
+
+static int cpcap_adc_init_request(struct cpcap_adc_request *req,
+				  int channel)
+{
+	req->channel = channel;
+	req->phase_tbl = bank_phasing;
+	req->conv_tbl = bank_conversion;
+
+	switch (channel) {
+	case CPCAP_ADC_AD0_BATTDETB ... CPCAP_ADC_USB_ID:
+		req->bank_index = channel;
+		break;
+	case CPCAP_ADC_AD8 ... CPCAP_ADC_TSY2_AD15:
+		req->bank_index = channel - 8;
+		break;
+	case CPCAP_ADC_BATTP_PI16:
+		req->bank_index = CPCAP_ADC_BATTP;
+		break;
+	case CPCAP_ADC_BATTI_PI17:
+		req->bank_index = CPCAP_ADC_BATTI;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	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 error;
+
+	error = cpcap_adc_init_request(&req, chan->channel);
+	if (error)
+		return error;
+
+	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_PROCESSED:
+		mutex_lock(&ddata->lock);
+		error = cpcap_adc_start_bank(ddata, &req);
+		if (error)
+			goto err_unlock;
+		error = cpcap_adc_read_bank_scaled(ddata, &req);
+		if (error)
+			goto err_unlock;
+		mutex_unlock(&ddata->lock);
+		*val = req.result;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	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;
+	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,
+					  IRQF_TRIGGER_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;
+
+	dev_info(&pdev->dev, "CPCAP ADC device probed\n");
+
+	return devm_iio_device_register(&pdev->dev, indio_dev);
+}
+
+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,
+};
+
+module_platform_driver(cpcap_adc_driver);
+
+MODULE_ALIAS("platform:cpcap_adc");
+MODULE_DESCRIPTION("CPCAP ADC driver");
+MODULE_AUTHOR("Tony Lindgren <tony@atomide.com");
+MODULE_LICENSE("GPL v2");