drivers/iio/adc/ad7791.c - pub/scm/linux/kernel/git/atull/linux-fpga - Git at Google

 /*
  * AD7787/AD7788/AD7789/AD7790/AD7791 SPI ADC driver
  *
  * Copyright 2012 Analog Devices Inc.
  *  Author: Lars-Peter Clausen <lars@metafoo.de>
  *
  * Licensed under the GPL-2.
  */

 #include <linux/interrupt.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/spi/spi.h>
 #include <linux/regulator/consumer.h>
 #include <linux/err.h>
 #include <linux/sched.h>
 #include <linux/delay.h>
 #include <linux/module.h>

 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/trigger.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/iio/adc/ad_sigma_delta.h>

 #include <linux/platform_data/ad7791.h>

 #define AD7791_REG_COMM			0x0 /* For writes */
 #define AD7791_REG_STATUS		0x0 /* For reads */
 #define AD7791_REG_MODE			0x1
 #define AD7791_REG_FILTER		0x2
 #define AD7791_REG_DATA			0x3

 #define AD7791_MODE_CONTINUOUS		0x00
 #define AD7791_MODE_SINGLE		0x02
 #define AD7791_MODE_POWERDOWN		0x03

 #define AD7791_CH_AIN1P_AIN1N		0x00
 #define AD7791_CH_AIN2			0x01
 #define AD7791_CH_AIN1N_AIN1N		0x02
 #define AD7791_CH_AVDD_MONITOR		0x03

 #define AD7791_FILTER_CLK_DIV_1		(0x0 << 4)
 #define AD7791_FILTER_CLK_DIV_2		(0x1 << 4)
 #define AD7791_FILTER_CLK_DIV_4		(0x2 << 4)
 #define AD7791_FILTER_CLK_DIV_8		(0x3 << 4)
 #define AD7791_FILTER_CLK_MASK		(0x3 << 4)
 #define AD7791_FILTER_RATE_120		0x0
 #define AD7791_FILTER_RATE_100		0x1
 #define AD7791_FILTER_RATE_33_3		0x2
 #define AD7791_FILTER_RATE_20		0x3
 #define AD7791_FILTER_RATE_16_6		0x4
 #define AD7791_FILTER_RATE_16_7		0x5
 #define AD7791_FILTER_RATE_13_3		0x6
 #define AD7791_FILTER_RATE_9_5		0x7
 #define AD7791_FILTER_RATE_MASK		0x7

 #define AD7791_MODE_BUFFER		BIT(1)
 #define AD7791_MODE_UNIPOLAR		BIT(2)
 #define AD7791_MODE_BURNOUT		BIT(3)
 #define AD7791_MODE_SEL_MASK		(0x3 << 6)
 #define AD7791_MODE_SEL(x)		((x) << 6)

 #define DECLARE_AD7787_CHANNELS(name, bits, storagebits) \
 const struct iio_chan_spec name[] = { \
 	AD_SD_DIFF_CHANNEL(0, 0, 0, AD7791_CH_AIN1P_AIN1N, \
 		(bits), (storagebits), 0), \
 	AD_SD_CHANNEL(1, 1, AD7791_CH_AIN2, (bits), (storagebits), 0), \
 	AD_SD_SHORTED_CHANNEL(2, 0, AD7791_CH_AIN1N_AIN1N, \
 		(bits), (storagebits), 0), \
 	AD_SD_SUPPLY_CHANNEL(3, 2, AD7791_CH_AVDD_MONITOR,  \
 		(bits), (storagebits), 0), \
 	IIO_CHAN_SOFT_TIMESTAMP(4), \
 }

 #define DECLARE_AD7791_CHANNELS(name, bits, storagebits) \
 const struct iio_chan_spec name[] = { \
 	AD_SD_DIFF_CHANNEL(0, 0, 0, AD7791_CH_AIN1P_AIN1N, \
 		(bits), (storagebits), 0), \
 	AD_SD_SHORTED_CHANNEL(1, 0, AD7791_CH_AIN1N_AIN1N, \
 		(bits), (storagebits), 0), \
 	AD_SD_SUPPLY_CHANNEL(2, 1, AD7791_CH_AVDD_MONITOR, \
 		(bits), (storagebits), 0), \
 	IIO_CHAN_SOFT_TIMESTAMP(3), \
 }

 static DECLARE_AD7787_CHANNELS(ad7787_channels, 24, 32);
 static DECLARE_AD7791_CHANNELS(ad7790_channels, 16, 16);
 static DECLARE_AD7791_CHANNELS(ad7791_channels, 24, 32);

 enum {
 	AD7787,
 	AD7788,
 	AD7789,
 	AD7790,
 	AD7791,
 };

 enum ad7791_chip_info_flags {
 	AD7791_FLAG_HAS_FILTER		= (1 << 0),
 	AD7791_FLAG_HAS_BUFFER		= (1 << 1),
 	AD7791_FLAG_HAS_UNIPOLAR	= (1 << 2),
 	AD7791_FLAG_HAS_BURNOUT		= (1 << 3),
 };

 struct ad7791_chip_info {
 	const struct iio_chan_spec *channels;
 	unsigned int num_channels;
 	enum ad7791_chip_info_flags flags;
 };

 static const struct ad7791_chip_info ad7791_chip_infos[] = {
 	[AD7787] = {
 		.channels = ad7787_channels,
 		.num_channels = ARRAY_SIZE(ad7787_channels),
 		.flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
 			AD7791_FLAG_HAS_UNIPOLAR | AD7791_FLAG_HAS_BURNOUT,
 	},
 	[AD7788] = {
 		.channels = ad7790_channels,
 		.num_channels = ARRAY_SIZE(ad7790_channels),
 		.flags = AD7791_FLAG_HAS_UNIPOLAR,
 	},
 	[AD7789] = {
 		.channels = ad7791_channels,
 		.num_channels = ARRAY_SIZE(ad7791_channels),
 		.flags = AD7791_FLAG_HAS_UNIPOLAR,
 	},
 	[AD7790] = {
 		.channels = ad7790_channels,
 		.num_channels = ARRAY_SIZE(ad7790_channels),
 		.flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
 			AD7791_FLAG_HAS_BURNOUT,
 	},
 	[AD7791] = {
 		.channels = ad7791_channels,
 		.num_channels = ARRAY_SIZE(ad7791_channels),
 		.flags = AD7791_FLAG_HAS_FILTER | AD7791_FLAG_HAS_BUFFER |
 			AD7791_FLAG_HAS_UNIPOLAR | AD7791_FLAG_HAS_BURNOUT,
 	},
 };

 struct ad7791_state {
 	struct ad_sigma_delta sd;
 	uint8_t mode;
 	uint8_t filter;

 	struct regulator *reg;
 	const struct ad7791_chip_info *info;
 };

 static struct ad7791_state *ad_sigma_delta_to_ad7791(struct ad_sigma_delta *sd)
 {
 	return container_of(sd, struct ad7791_state, sd);
 }

 static int ad7791_set_channel(struct ad_sigma_delta *sd, unsigned int channel)
 {
 	ad_sd_set_comm(sd, channel);

 	return 0;
 }

 static int ad7791_set_mode(struct ad_sigma_delta *sd,
 	enum ad_sigma_delta_mode mode)
 {
 	struct ad7791_state *st = ad_sigma_delta_to_ad7791(sd);

 	switch (mode) {
 	case AD_SD_MODE_CONTINUOUS:
 		mode = AD7791_MODE_CONTINUOUS;
 		break;
 	case AD_SD_MODE_SINGLE:
 		mode = AD7791_MODE_SINGLE;
 		break;
 	case AD_SD_MODE_IDLE:
 	case AD_SD_MODE_POWERDOWN:
 		mode = AD7791_MODE_POWERDOWN;
 		break;
 	}

 	st->mode &= ~AD7791_MODE_SEL_MASK;
 	st->mode |= AD7791_MODE_SEL(mode);

 	return ad_sd_write_reg(sd, AD7791_REG_MODE, sizeof(st->mode), st->mode);
 }

 static const struct ad_sigma_delta_info ad7791_sigma_delta_info = {
 	.set_channel = ad7791_set_channel,
 	.set_mode = ad7791_set_mode,
 	.has_registers = true,
 	.addr_shift = 4,
 	.read_mask = BIT(3),
 };

 static int ad7791_read_raw(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, int *val, int *val2, long info)
 {
 	struct ad7791_state *st = iio_priv(indio_dev);
 	bool unipolar = !!(st->mode & AD7791_MODE_UNIPOLAR);

 	switch (info) {
 	case IIO_CHAN_INFO_RAW:
 		return ad_sigma_delta_single_conversion(indio_dev, chan, val);
 	case IIO_CHAN_INFO_OFFSET:
 		/**
 		 * Unipolar: 0 to VREF
 		 * Bipolar -VREF to VREF
 		 **/
 		if (unipolar)
 			*val = 0;
 		else
 			*val = -(1 << (chan->scan_type.realbits - 1));
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		/* The monitor channel uses an internal reference. */
 		if (chan->address == AD7791_CH_AVDD_MONITOR) {
 			/*
 			 * The signal is attenuated by a factor of 5 and
 			 * compared against a 1.17V internal reference.
 			 */
 			*val = 1170 * 5;
 		} else {
 			int voltage_uv;

 			voltage_uv = regulator_get_voltage(st->reg);
 			if (voltage_uv < 0)
 				return voltage_uv;

 			*val = voltage_uv / 1000;
 		}
 		if (unipolar)
 			*val2 = chan->scan_type.realbits;
 		else
 			*val2 = chan->scan_type.realbits - 1;

 		return IIO_VAL_FRACTIONAL_LOG2;
 	}

 	return -EINVAL;
 }

 static const char * const ad7791_sample_freq_avail[] = {
 	[AD7791_FILTER_RATE_120] = "120",
 	[AD7791_FILTER_RATE_100] = "100",
 	[AD7791_FILTER_RATE_33_3] = "33.3",
 	[AD7791_FILTER_RATE_20] = "20",
 	[AD7791_FILTER_RATE_16_6] = "16.6",
 	[AD7791_FILTER_RATE_16_7] = "16.7",
 	[AD7791_FILTER_RATE_13_3] = "13.3",
 	[AD7791_FILTER_RATE_9_5] = "9.5",
 };

 static ssize_t ad7791_read_frequency(struct device *dev,
 	struct device_attribute *attr, char *buf)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct ad7791_state *st = iio_priv(indio_dev);
 	unsigned int rate = st->filter & AD7791_FILTER_RATE_MASK;

 	return sprintf(buf, "%s\n", ad7791_sample_freq_avail[rate]);
 }

 static ssize_t ad7791_write_frequency(struct device *dev,
 	struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct ad7791_state *st = iio_priv(indio_dev);
 	int i, ret;

 	for (i = 0; i < ARRAY_SIZE(ad7791_sample_freq_avail); i++)
 		if (sysfs_streq(ad7791_sample_freq_avail[i], buf))
 			break;
 	if (i == ARRAY_SIZE(ad7791_sample_freq_avail))
 		return -EINVAL;

 	ret = iio_device_claim_direct_mode(indio_dev);
 	if (ret)
 		return ret;
 	st->filter &= ~AD7791_FILTER_RATE_MASK;
 	st->filter |= i;
 	ad_sd_write_reg(&st->sd, AD7791_REG_FILTER, sizeof(st->filter),
 			st->filter);
 	iio_device_release_direct_mode(indio_dev);

 	return len;
 }

 static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,
 		ad7791_read_frequency,
 		ad7791_write_frequency);

 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("120 100 33.3 20 16.7 16.6 13.3 9.5");

 static struct attribute *ad7791_attributes[] = {
 	&iio_dev_attr_sampling_frequency.dev_attr.attr,
 	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group ad7791_attribute_group = {
 	.attrs = ad7791_attributes,
 };

 static const struct iio_info ad7791_info = {
 	.read_raw = &ad7791_read_raw,
 	.attrs = &ad7791_attribute_group,
 	.validate_trigger = ad_sd_validate_trigger,
 	.driver_module = THIS_MODULE,
 };

 static const struct iio_info ad7791_no_filter_info = {
 	.read_raw = &ad7791_read_raw,
 	.validate_trigger = ad_sd_validate_trigger,
 	.driver_module = THIS_MODULE,
 };

 static int ad7791_setup(struct ad7791_state *st,
 			struct ad7791_platform_data *pdata)
 {
 	/* Set to poweron-reset default values */
 	st->mode = AD7791_MODE_BUFFER;
 	st->filter = AD7791_FILTER_RATE_16_6;

 	if (!pdata)
 		return 0;

 	if ((st->info->flags & AD7791_FLAG_HAS_BUFFER) && !pdata->buffered)
 		st->mode &= ~AD7791_MODE_BUFFER;

 	if ((st->info->flags & AD7791_FLAG_HAS_BURNOUT) &&
 		pdata->burnout_current)
 		st->mode |= AD7791_MODE_BURNOUT;

 	if ((st->info->flags & AD7791_FLAG_HAS_UNIPOLAR) && pdata->unipolar)
 		st->mode |= AD7791_MODE_UNIPOLAR;

 	return ad_sd_write_reg(&st->sd, AD7791_REG_MODE, sizeof(st->mode),
 		st->mode);
 }

 static int ad7791_probe(struct spi_device *spi)
 {
 	struct ad7791_platform_data *pdata = spi->dev.platform_data;
 	struct iio_dev *indio_dev;
 	struct ad7791_state *st;
 	int ret;

 	if (!spi->irq) {
 		dev_err(&spi->dev, "Missing IRQ.\n");
 		return -ENXIO;
 	}

 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
 	if (!indio_dev)
 		return -ENOMEM;

 	st = iio_priv(indio_dev);

 	st->reg = devm_regulator_get(&spi->dev, "refin");
 	if (IS_ERR(st->reg))
 		return PTR_ERR(st->reg);

 	ret = regulator_enable(st->reg);
 	if (ret)
 		return ret;

 	st->info = &ad7791_chip_infos[spi_get_device_id(spi)->driver_data];
 	ad_sd_init(&st->sd, indio_dev, spi, &ad7791_sigma_delta_info);

 	spi_set_drvdata(spi, indio_dev);

 	indio_dev->dev.parent = &spi->dev;
 	indio_dev->dev.of_node = spi->dev.of_node;
 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = st->info->channels;
 	indio_dev->num_channels = st->info->num_channels;
 	if (st->info->flags & AD7791_FLAG_HAS_FILTER)
 		indio_dev->info = &ad7791_info;
 	else
 		indio_dev->info = &ad7791_no_filter_info;

 	ret = ad_sd_setup_buffer_and_trigger(indio_dev);
 	if (ret)
 		goto error_disable_reg;

 	ret = ad7791_setup(st, pdata);
 	if (ret)
 		goto error_remove_trigger;

 	ret = iio_device_register(indio_dev);
 	if (ret)
 		goto error_remove_trigger;

 	return 0;

 error_remove_trigger:
 	ad_sd_cleanup_buffer_and_trigger(indio_dev);
 error_disable_reg:
 	regulator_disable(st->reg);

 	return ret;
 }

 static int ad7791_remove(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
 	struct ad7791_state *st = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);
 	ad_sd_cleanup_buffer_and_trigger(indio_dev);

 	regulator_disable(st->reg);

 	return 0;
 }

 static const struct spi_device_id ad7791_spi_ids[] = {
 	{ "ad7787", AD7787 },
 	{ "ad7788", AD7788 },
 	{ "ad7789", AD7789 },
 	{ "ad7790", AD7790 },
 	{ "ad7791", AD7791 },
 	{}
 };
 MODULE_DEVICE_TABLE(spi, ad7791_spi_ids);

 static struct spi_driver ad7791_driver = {
 	.driver = {
 		.name	= "ad7791",
 	},
 	.probe		= ad7791_probe,
 	.remove		= ad7791_remove,
 	.id_table	= ad7791_spi_ids,
 };
 module_spi_driver(ad7791_driver);

 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 MODULE_DESCRIPTION("Analog Device AD7787/AD7788/AD7789/AD7790/AD7791 ADC driver");
 MODULE_LICENSE("GPL v2");
	/*
	* AD7787/AD7788/AD7789/AD7790/AD7791 SPI ADC driver
	*
	* Copyright 2012 Analog Devices Inc.
	* Author: Lars-Peter Clausen <lars@metafoo.de>
	*
	* Licensed under the GPL-2.
	*/

	#include <linux/interrupt.h>
	#include <linux/device.h>
	#include <linux/kernel.h>
	#include <linux/slab.h>
	#include <linux/sysfs.h>
	#include <linux/spi/spi.h>
	#include <linux/regulator/consumer.h>
	#include <linux/err.h>
	#include <linux/sched.h>
	#include <linux/delay.h>
	#include <linux/module.h>

	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/iio/buffer.h>
	#include <linux/iio/trigger.h>
	#include <linux/iio/trigger_consumer.h>
	#include <linux/iio/triggered_buffer.h>
	#include <linux/iio/adc/ad_sigma_delta.h>

	#include <linux/platform_data/ad7791.h>

	#define AD7791_REG_COMM 0x0 /* For writes */
	#define AD7791_REG_STATUS 0x0 /* For reads */
	#define AD7791_REG_MODE 0x1
	#define AD7791_REG_FILTER 0x2
	#define AD7791_REG_DATA 0x3

	#define AD7791_MODE_CONTINUOUS 0x00
	#define AD7791_MODE_SINGLE 0x02
	#define AD7791_MODE_POWERDOWN 0x03

	#define AD7791_CH_AIN1P_AIN1N 0x00
	#define AD7791_CH_AIN2 0x01
	#define AD7791_CH_AIN1N_AIN1N 0x02
	#define AD7791_CH_AVDD_MONITOR 0x03

	#define AD7791_FILTER_CLK_DIV_1 (0x0 << 4)
	#define AD7791_FILTER_CLK_DIV_2 (0x1 << 4)
	#define AD7791_FILTER_CLK_DIV_4 (0x2 << 4)
	#define AD7791_FILTER_CLK_DIV_8 (0x3 << 4)
	#define AD7791_FILTER_CLK_MASK (0x3 << 4)
	#define AD7791_FILTER_RATE_120 0x0
	#define AD7791_FILTER_RATE_100 0x1
	#define AD7791_FILTER_RATE_33_3 0x2
	#define AD7791_FILTER_RATE_20 0x3
	#define AD7791_FILTER_RATE_16_6 0x4
	#define AD7791_FILTER_RATE_16_7 0x5
	#define AD7791_FILTER_RATE_13_3 0x6
	#define AD7791_FILTER_RATE_9_5 0x7
	#define AD7791_FILTER_RATE_MASK 0x7

	#define AD7791_MODE_BUFFER BIT(1)
	#define AD7791_MODE_UNIPOLAR BIT(2)
	#define AD7791_MODE_BURNOUT BIT(3)
	#define AD7791_MODE_SEL_MASK (0x3 << 6)
	#define AD7791_MODE_SEL(x) ((x) << 6)

	#define DECLARE_AD7787_CHANNELS(name, bits, storagebits) \
	const struct iio_chan_spec name[] = { \
	AD_SD_DIFF_CHANNEL(0, 0, 0, AD7791_CH_AIN1P_AIN1N, \
	(bits), (storagebits), 0), \
	AD_SD_CHANNEL(1, 1, AD7791_CH_AIN2, (bits), (storagebits), 0), \
	AD_SD_SHORTED_CHANNEL(2, 0, AD7791_CH_AIN1N_AIN1N, \
	(bits), (storagebits), 0), \
	AD_SD_SUPPLY_CHANNEL(3, 2, AD7791_CH_AVDD_MONITOR, \
	(bits), (storagebits), 0), \
	IIO_CHAN_SOFT_TIMESTAMP(4), \
	}

	#define DECLARE_AD7791_CHANNELS(name, bits, storagebits) \
	const struct iio_chan_spec name[] = { \
	AD_SD_DIFF_CHANNEL(0, 0, 0, AD7791_CH_AIN1P_AIN1N, \
	(bits), (storagebits), 0), \
	AD_SD_SHORTED_CHANNEL(1, 0, AD7791_CH_AIN1N_AIN1N, \
	(bits), (storagebits), 0), \
	AD_SD_SUPPLY_CHANNEL(2, 1, AD7791_CH_AVDD_MONITOR, \
	(bits), (storagebits), 0), \
	IIO_CHAN_SOFT_TIMESTAMP(3), \
	}

	static DECLARE_AD7787_CHANNELS(ad7787_channels, 24, 32);
	static DECLARE_AD7791_CHANNELS(ad7790_channels, 16, 16);
	static DECLARE_AD7791_CHANNELS(ad7791_channels, 24, 32);

	enum {
	AD7787,
	AD7788,
	AD7789,
	AD7790,
	AD7791,
	};

	enum ad7791_chip_info_flags {
	AD7791_FLAG_HAS_FILTER = (1 << 0),
	AD7791_FLAG_HAS_BUFFER = (1 << 1),
	AD7791_FLAG_HAS_UNIPOLAR = (1 << 2),
	AD7791_FLAG_HAS_BURNOUT = (1 << 3),
	};

	struct ad7791_chip_info {
	const struct iio_chan_spec *channels;
	unsigned int num_channels;
	enum ad7791_chip_info_flags flags;
	};

	static const struct ad7791_chip_info ad7791_chip_infos[] = {
	[AD7787] = {
	.channels = ad7787_channels,
	.num_channels = ARRAY_SIZE(ad7787_channels),
	.flags = AD7791_FLAG_HAS_FILTER \| AD7791_FLAG_HAS_BUFFER \|
	AD7791_FLAG_HAS_UNIPOLAR \| AD7791_FLAG_HAS_BURNOUT,
	},
	[AD7788] = {
	.channels = ad7790_channels,
	.num_channels = ARRAY_SIZE(ad7790_channels),
	.flags = AD7791_FLAG_HAS_UNIPOLAR,
	},
	[AD7789] = {
	.channels = ad7791_channels,
	.num_channels = ARRAY_SIZE(ad7791_channels),
	.flags = AD7791_FLAG_HAS_UNIPOLAR,
	},
	[AD7790] = {
	.channels = ad7790_channels,
	.num_channels = ARRAY_SIZE(ad7790_channels),
	.flags = AD7791_FLAG_HAS_FILTER \| AD7791_FLAG_HAS_BUFFER \|
	AD7791_FLAG_HAS_BURNOUT,
	},
	[AD7791] = {
	.channels = ad7791_channels,
	.num_channels = ARRAY_SIZE(ad7791_channels),
	.flags = AD7791_FLAG_HAS_FILTER \| AD7791_FLAG_HAS_BUFFER \|
	AD7791_FLAG_HAS_UNIPOLAR \| AD7791_FLAG_HAS_BURNOUT,
	},
	};

	struct ad7791_state {
	struct ad_sigma_delta sd;
	uint8_t mode;
	uint8_t filter;

	struct regulator *reg;
	const struct ad7791_chip_info *info;
	};

	static struct ad7791_state ad_sigma_delta_to_ad7791(struct ad_sigma_delta sd)
	{
	return container_of(sd, struct ad7791_state, sd);
	}

	static int ad7791_set_channel(struct ad_sigma_delta *sd, unsigned int channel)
	{
	ad_sd_set_comm(sd, channel);

	return 0;
	}

	static int ad7791_set_mode(struct ad_sigma_delta *sd,
	enum ad_sigma_delta_mode mode)
	{
	struct ad7791_state *st = ad_sigma_delta_to_ad7791(sd);

	switch (mode) {
	case AD_SD_MODE_CONTINUOUS:
	mode = AD7791_MODE_CONTINUOUS;
	break;
	case AD_SD_MODE_SINGLE:
	mode = AD7791_MODE_SINGLE;
	break;
	case AD_SD_MODE_IDLE:
	case AD_SD_MODE_POWERDOWN:
	mode = AD7791_MODE_POWERDOWN;
	break;
	}

	st->mode &= ~AD7791_MODE_SEL_MASK;
	st->mode \|= AD7791_MODE_SEL(mode);

	return ad_sd_write_reg(sd, AD7791_REG_MODE, sizeof(st->mode), st->mode);
	}

	static const struct ad_sigma_delta_info ad7791_sigma_delta_info = {
	.set_channel = ad7791_set_channel,
	.set_mode = ad7791_set_mode,
	.has_registers = true,
	.addr_shift = 4,
	.read_mask = BIT(3),
	};

	static int ad7791_read_raw(struct iio_dev *indio_dev,
	const struct iio_chan_spec chan, int val, int *val2, long info)
	{
	struct ad7791_state *st = iio_priv(indio_dev);
	bool unipolar = !!(st->mode & AD7791_MODE_UNIPOLAR);

	switch (info) {
	case IIO_CHAN_INFO_RAW:
	return ad_sigma_delta_single_conversion(indio_dev, chan, val);
	case IIO_CHAN_INFO_OFFSET:
	/**
	* Unipolar: 0 to VREF
	* Bipolar -VREF to VREF
	**/
	if (unipolar)
	*val = 0;
	else
	*val = -(1 << (chan->scan_type.realbits - 1));
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	/* The monitor channel uses an internal reference. */
	if (chan->address == AD7791_CH_AVDD_MONITOR) {
	/*
	* The signal is attenuated by a factor of 5 and
	* compared against a 1.17V internal reference.
	*/
	val = 1170 5;
	} else {
	int voltage_uv;

	voltage_uv = regulator_get_voltage(st->reg);
	if (voltage_uv < 0)
	return voltage_uv;

	*val = voltage_uv / 1000;
	}
	if (unipolar)
	*val2 = chan->scan_type.realbits;
	else
	*val2 = chan->scan_type.realbits - 1;

	return IIO_VAL_FRACTIONAL_LOG2;
	}

	return -EINVAL;
	}

	static const char * const ad7791_sample_freq_avail[] = {
	[AD7791_FILTER_RATE_120] = "120",
	[AD7791_FILTER_RATE_100] = "100",
	[AD7791_FILTER_RATE_33_3] = "33.3",
	[AD7791_FILTER_RATE_20] = "20",
	[AD7791_FILTER_RATE_16_6] = "16.6",
	[AD7791_FILTER_RATE_16_7] = "16.7",
	[AD7791_FILTER_RATE_13_3] = "13.3",
	[AD7791_FILTER_RATE_9_5] = "9.5",
	};

	static ssize_t ad7791_read_frequency(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ad7791_state *st = iio_priv(indio_dev);
	unsigned int rate = st->filter & AD7791_FILTER_RATE_MASK;

	return sprintf(buf, "%s\n", ad7791_sample_freq_avail[rate]);
	}

	static ssize_t ad7791_write_frequency(struct device *dev,
	struct device_attribute attr, const char buf, size_t len)
	{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ad7791_state *st = iio_priv(indio_dev);
	int i, ret;

	for (i = 0; i < ARRAY_SIZE(ad7791_sample_freq_avail); i++)
	if (sysfs_streq(ad7791_sample_freq_avail[i], buf))
	break;
	if (i == ARRAY_SIZE(ad7791_sample_freq_avail))
	return -EINVAL;

	ret = iio_device_claim_direct_mode(indio_dev);
	if (ret)
	return ret;
	st->filter &= ~AD7791_FILTER_RATE_MASK;
	st->filter \|= i;
	ad_sd_write_reg(&st->sd, AD7791_REG_FILTER, sizeof(st->filter),
	st->filter);
	iio_device_release_direct_mode(indio_dev);

	return len;
	}

	static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR \| S_IRUGO,
	ad7791_read_frequency,
	ad7791_write_frequency);

	static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("120 100 33.3 20 16.7 16.6 13.3 9.5");

	static struct attribute *ad7791_attributes[] = {
	&iio_dev_attr_sampling_frequency.dev_attr.attr,
	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
	NULL
	};

	static const struct attribute_group ad7791_attribute_group = {
	.attrs = ad7791_attributes,
	};

	static const struct iio_info ad7791_info = {
	.read_raw = &ad7791_read_raw,
	.attrs = &ad7791_attribute_group,
	.validate_trigger = ad_sd_validate_trigger,
	.driver_module = THIS_MODULE,
	};

	static const struct iio_info ad7791_no_filter_info = {
	.read_raw = &ad7791_read_raw,
	.validate_trigger = ad_sd_validate_trigger,
	.driver_module = THIS_MODULE,
	};

	static int ad7791_setup(struct ad7791_state *st,
	struct ad7791_platform_data *pdata)
	{
	/* Set to poweron-reset default values */
	st->mode = AD7791_MODE_BUFFER;
	st->filter = AD7791_FILTER_RATE_16_6;

	if (!pdata)
	return 0;

	if ((st->info->flags & AD7791_FLAG_HAS_BUFFER) && !pdata->buffered)
	st->mode &= ~AD7791_MODE_BUFFER;

	if ((st->info->flags & AD7791_FLAG_HAS_BURNOUT) &&
	pdata->burnout_current)
	st->mode \|= AD7791_MODE_BURNOUT;

	if ((st->info->flags & AD7791_FLAG_HAS_UNIPOLAR) && pdata->unipolar)
	st->mode \|= AD7791_MODE_UNIPOLAR;

	return ad_sd_write_reg(&st->sd, AD7791_REG_MODE, sizeof(st->mode),
	st->mode);
	}

	static int ad7791_probe(struct spi_device *spi)
	{
	struct ad7791_platform_data *pdata = spi->dev.platform_data;
	struct iio_dev *indio_dev;
	struct ad7791_state *st;
	int ret;

	if (!spi->irq) {
	dev_err(&spi->dev, "Missing IRQ.\n");
	return -ENXIO;
	}

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
	if (!indio_dev)
	return -ENOMEM;

	st = iio_priv(indio_dev);

	st->reg = devm_regulator_get(&spi->dev, "refin");
	if (IS_ERR(st->reg))
	return PTR_ERR(st->reg);

	ret = regulator_enable(st->reg);
	if (ret)
	return ret;

	st->info = &ad7791_chip_infos[spi_get_device_id(spi)->driver_data];
	ad_sd_init(&st->sd, indio_dev, spi, &ad7791_sigma_delta_info);

	spi_set_drvdata(spi, indio_dev);

	indio_dev->dev.parent = &spi->dev;
	indio_dev->dev.of_node = spi->dev.of_node;
	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = st->info->channels;
	indio_dev->num_channels = st->info->num_channels;
	if (st->info->flags & AD7791_FLAG_HAS_FILTER)
	indio_dev->info = &ad7791_info;
	else
	indio_dev->info = &ad7791_no_filter_info;

	ret = ad_sd_setup_buffer_and_trigger(indio_dev);
	if (ret)
	goto error_disable_reg;

	ret = ad7791_setup(st, pdata);
	if (ret)
	goto error_remove_trigger;

	ret = iio_device_register(indio_dev);
	if (ret)
	goto error_remove_trigger;

	return 0;

	error_remove_trigger:
	ad_sd_cleanup_buffer_and_trigger(indio_dev);
	error_disable_reg:
	regulator_disable(st->reg);

	return ret;
	}

	static int ad7791_remove(struct spi_device *spi)
	{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct ad7791_state *st = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	ad_sd_cleanup_buffer_and_trigger(indio_dev);

	regulator_disable(st->reg);

	return 0;
	}

	static const struct spi_device_id ad7791_spi_ids[] = {
	{ "ad7787", AD7787 },
	{ "ad7788", AD7788 },
	{ "ad7789", AD7789 },
	{ "ad7790", AD7790 },
	{ "ad7791", AD7791 },
	{}
	};
	MODULE_DEVICE_TABLE(spi, ad7791_spi_ids);

	static struct spi_driver ad7791_driver = {
	.driver = {
	.name = "ad7791",
	},
	.probe = ad7791_probe,
	.remove = ad7791_remove,
	.id_table = ad7791_spi_ids,
	};
	module_spi_driver(ad7791_driver);

	MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
	MODULE_DESCRIPTION("Analog Device AD7787/AD7788/AD7789/AD7790/AD7791 ADC driver");
	MODULE_LICENSE("GPL v2");