drivers/iio/dac/ad5791.c - maze/linux - Git at Google

 /*
  * AD5760, AD5780, AD5781, AD5790, AD5791 Voltage Output Digital to Analog
  * Converter
  *
  * Copyright 2011 Analog Devices Inc.
  *
  * Licensed under the GPL-2.
  */

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

 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/dac/ad5791.h>

 #define AD5791_RES_MASK(x)		((1 << (x)) - 1)
 #define AD5791_DAC_MASK			AD5791_RES_MASK(20)
 #define AD5791_DAC_MSB			(1 << 19)

 #define AD5791_CMD_READ			(1 << 23)
 #define AD5791_CMD_WRITE		(0 << 23)
 #define AD5791_ADDR(addr)		((addr) << 20)

 /* Registers */
 #define AD5791_ADDR_NOOP		0
 #define AD5791_ADDR_DAC0		1
 #define AD5791_ADDR_CTRL		2
 #define AD5791_ADDR_CLRCODE		3
 #define AD5791_ADDR_SW_CTRL		4

 /* Control Register */
 #define AD5791_CTRL_RBUF		(1 << 1)
 #define AD5791_CTRL_OPGND		(1 << 2)
 #define AD5791_CTRL_DACTRI		(1 << 3)
 #define AD5791_CTRL_BIN2SC		(1 << 4)
 #define AD5791_CTRL_SDODIS		(1 << 5)
 #define AD5761_CTRL_LINCOMP(x)		((x) << 6)

 #define AD5791_LINCOMP_0_10		0
 #define AD5791_LINCOMP_10_12		1
 #define AD5791_LINCOMP_12_16		2
 #define AD5791_LINCOMP_16_19		3
 #define AD5791_LINCOMP_19_20		12

 #define AD5780_LINCOMP_0_10		0
 #define AD5780_LINCOMP_10_20		12

 /* Software Control Register */
 #define AD5791_SWCTRL_LDAC		(1 << 0)
 #define AD5791_SWCTRL_CLR		(1 << 1)
 #define AD5791_SWCTRL_RESET		(1 << 2)

 #define AD5791_DAC_PWRDN_6K		0
 #define AD5791_DAC_PWRDN_3STATE		1

 /**
  * struct ad5791_chip_info - chip specific information
  * @get_lin_comp:	function pointer to the device specific function
  */

 struct ad5791_chip_info {
 	int (*get_lin_comp)	(unsigned int span);
 };

 /**
  * struct ad5791_state - driver instance specific data
  * @us:			spi_device
  * @reg_vdd:		positive supply regulator
  * @reg_vss:		negative supply regulator
  * @chip_info:		chip model specific constants
  * @vref_mv:		actual reference voltage used
  * @vref_neg_mv:	voltage of the negative supply
  * @pwr_down_mode	current power down mode
  */

 struct ad5791_state {
 	struct spi_device		*spi;
 	struct regulator		*reg_vdd;
 	struct regulator		*reg_vss;
 	const struct ad5791_chip_info	*chip_info;
 	unsigned short			vref_mv;
 	unsigned int			vref_neg_mv;
 	unsigned			ctrl;
 	unsigned			pwr_down_mode;
 	bool				pwr_down;
 };

 /**
  * ad5791_supported_device_ids:
  */

 enum ad5791_supported_device_ids {
 	ID_AD5760,
 	ID_AD5780,
 	ID_AD5781,
 	ID_AD5791,
 };

 static int ad5791_spi_write(struct spi_device *spi, u8 addr, u32 val)
 {
 	union {
 		u32 d32;
 		u8 d8[4];
 	} data;

 	data.d32 = cpu_to_be32(AD5791_CMD_WRITE |
 			      AD5791_ADDR(addr) |
 			      (val & AD5791_DAC_MASK));

 	return spi_write(spi, &data.d8[1], 3);
 }

 static int ad5791_spi_read(struct spi_device *spi, u8 addr, u32 *val)
 {
 	union {
 		u32 d32;
 		u8 d8[4];
 	} data[3];
 	int ret;
 	struct spi_message msg;
 	struct spi_transfer xfers[] = {
 		{
 			.tx_buf = &data[0].d8[1],
 			.bits_per_word = 8,
 			.len = 3,
 			.cs_change = 1,
 		}, {
 			.tx_buf = &data[1].d8[1],
 			.rx_buf = &data[2].d8[1],
 			.bits_per_word = 8,
 			.len = 3,
 		},
 	};

 	data[0].d32 = cpu_to_be32(AD5791_CMD_READ |
 			      AD5791_ADDR(addr));
 	data[1].d32 = cpu_to_be32(AD5791_ADDR(AD5791_ADDR_NOOP));

 	spi_message_init(&msg);
 	spi_message_add_tail(&xfers[0], &msg);
 	spi_message_add_tail(&xfers[1], &msg);
 	ret = spi_sync(spi, &msg);

 	*val = be32_to_cpu(data[2].d32);

 	return ret;
 }

 static const char * const ad5791_powerdown_modes[] = {
 	"6kohm_to_gnd",
 	"three_state",
 };

 static int ad5791_get_powerdown_mode(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan)
 {
 	struct ad5791_state *st = iio_priv(indio_dev);

 	return st->pwr_down_mode;
 }

 static int ad5791_set_powerdown_mode(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, unsigned int mode)
 {
 	struct ad5791_state *st = iio_priv(indio_dev);

 	st->pwr_down_mode = mode;

 	return 0;
 }

 static const struct iio_enum ad5791_powerdown_mode_enum = {
 	.items = ad5791_powerdown_modes,
 	.num_items = ARRAY_SIZE(ad5791_powerdown_modes),
 	.get = ad5791_get_powerdown_mode,
 	.set = ad5791_set_powerdown_mode,
 };

 static ssize_t ad5791_read_dac_powerdown(struct iio_dev *indio_dev,
 	uintptr_t private, const struct iio_chan_spec *chan, char *buf)
 {
 	struct ad5791_state *st = iio_priv(indio_dev);

 	return sprintf(buf, "%d\n", st->pwr_down);
 }

 static ssize_t ad5791_write_dac_powerdown(struct iio_dev *indio_dev,
 	 uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
 	 size_t len)
 {
 	bool pwr_down;
 	int ret;
 	struct ad5791_state *st = iio_priv(indio_dev);

 	ret = strtobool(buf, &pwr_down);
 	if (ret)
 		return ret;

 	if (!pwr_down) {
 		st->ctrl &= ~(AD5791_CTRL_OPGND | AD5791_CTRL_DACTRI);
 	} else {
 		if (st->pwr_down_mode == AD5791_DAC_PWRDN_6K)
 			st->ctrl |= AD5791_CTRL_OPGND;
 		else if (st->pwr_down_mode == AD5791_DAC_PWRDN_3STATE)
 			st->ctrl |= AD5791_CTRL_DACTRI;
 	}
 	st->pwr_down = pwr_down;

 	ret = ad5791_spi_write(st->spi, AD5791_ADDR_CTRL, st->ctrl);

 	return ret ? ret : len;
 }

 static int ad5791_get_lin_comp(unsigned int span)
 {
 	if (span <= 10000)
 		return AD5791_LINCOMP_0_10;
 	else if (span <= 12000)
 		return AD5791_LINCOMP_10_12;
 	else if (span <= 16000)
 		return AD5791_LINCOMP_12_16;
 	else if (span <= 19000)
 		return AD5791_LINCOMP_16_19;
 	else
 		return AD5791_LINCOMP_19_20;
 }

 static int ad5780_get_lin_comp(unsigned int span)
 {
 	if (span <= 10000)
 		return AD5780_LINCOMP_0_10;
 	else
 		return AD5780_LINCOMP_10_20;
 }
 static const struct ad5791_chip_info ad5791_chip_info_tbl[] = {
 	[ID_AD5760] = {
 		.get_lin_comp = ad5780_get_lin_comp,
 	},
 	[ID_AD5780] = {
 		.get_lin_comp = ad5780_get_lin_comp,
 	},
 	[ID_AD5781] = {
 		.get_lin_comp = ad5791_get_lin_comp,
 	},
 	[ID_AD5791] = {
 		.get_lin_comp = ad5791_get_lin_comp,
 	},
 };

 static int ad5791_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val,
 			   int *val2,
 			   long m)
 {
 	struct ad5791_state *st = iio_priv(indio_dev);
 	u64 val64;
 	int ret;

 	switch (m) {
 	case IIO_CHAN_INFO_RAW:
 		ret = ad5791_spi_read(st->spi, chan->address, val);
 		if (ret)
 			return ret;
 		*val &= AD5791_DAC_MASK;
 		*val >>= chan->scan_type.shift;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		*val = 0;
 		*val2 = (((u64)st->vref_mv) * 1000000ULL) >> chan->scan_type.realbits;
 		return IIO_VAL_INT_PLUS_MICRO;
 	case IIO_CHAN_INFO_OFFSET:
 		val64 = (((u64)st->vref_neg_mv) << chan->scan_type.realbits);
 		do_div(val64, st->vref_mv);
 		*val = -val64;
 		return IIO_VAL_INT;
 	default:
 		return -EINVAL;
 	}

 };

 static const struct iio_chan_spec_ext_info ad5791_ext_info[] = {
 	{
 		.name = "powerdown",
 		.shared = true,
 		.read = ad5791_read_dac_powerdown,
 		.write = ad5791_write_dac_powerdown,
 	},
 	IIO_ENUM("powerdown_mode", true, &ad5791_powerdown_mode_enum),
 	IIO_ENUM_AVAILABLE("powerdown_mode", &ad5791_powerdown_mode_enum),
 	{ },
 };

 #define AD5791_CHAN(bits, shift) {			\
 	.type = IIO_VOLTAGE,				\
 	.output = 1,					\
 	.indexed = 1,					\
 	.address = AD5791_ADDR_DAC0,			\
 	.channel = 0,					\
 	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |	\
 		IIO_CHAN_INFO_SCALE_SHARED_BIT |	\
 		IIO_CHAN_INFO_OFFSET_SHARED_BIT,	\
 	.scan_type = IIO_ST('u', bits, 24, shift),	\
 	.ext_info = ad5791_ext_info,			\
 }

 static const struct iio_chan_spec ad5791_channels[] = {
 	[ID_AD5760] = AD5791_CHAN(16, 4),
 	[ID_AD5780] = AD5791_CHAN(18, 2),
 	[ID_AD5781] = AD5791_CHAN(18, 2),
 	[ID_AD5791] = AD5791_CHAN(20, 0)
 };

 static int ad5791_write_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int val,
 			    int val2,
 			    long mask)
 {
 	struct ad5791_state *st = iio_priv(indio_dev);

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		val &= AD5791_RES_MASK(chan->scan_type.realbits);
 		val <<= chan->scan_type.shift;

 		return ad5791_spi_write(st->spi, chan->address, val);

 	default:
 		return -EINVAL;
 	}
 }

 static const struct iio_info ad5791_info = {
 	.read_raw = &ad5791_read_raw,
 	.write_raw = &ad5791_write_raw,
 	.driver_module = THIS_MODULE,
 };

 static int __devinit ad5791_probe(struct spi_device *spi)
 {
 	struct ad5791_platform_data *pdata = spi->dev.platform_data;
 	struct iio_dev *indio_dev;
 	struct ad5791_state *st;
 	int ret, pos_voltage_uv = 0, neg_voltage_uv = 0;

 	indio_dev = iio_device_alloc(sizeof(*st));
 	if (indio_dev == NULL) {
 		ret = -ENOMEM;
 		goto error_ret;
 	}
 	st = iio_priv(indio_dev);
 	st->reg_vdd = regulator_get(&spi->dev, "vdd");
 	if (!IS_ERR(st->reg_vdd)) {
 		ret = regulator_enable(st->reg_vdd);
 		if (ret)
 			goto error_put_reg_pos;

 		pos_voltage_uv = regulator_get_voltage(st->reg_vdd);
 	}

 	st->reg_vss = regulator_get(&spi->dev, "vss");
 	if (!IS_ERR(st->reg_vss)) {
 		ret = regulator_enable(st->reg_vss);
 		if (ret)
 			goto error_put_reg_neg;

 		neg_voltage_uv = regulator_get_voltage(st->reg_vss);
 	}

 	st->pwr_down = true;
 	st->spi = spi;

 	if (!IS_ERR(st->reg_vss) && !IS_ERR(st->reg_vdd)) {
 		st->vref_mv = (pos_voltage_uv + neg_voltage_uv) / 1000;
 		st->vref_neg_mv = neg_voltage_uv / 1000;
 	} else if (pdata) {
 		st->vref_mv = pdata->vref_pos_mv + pdata->vref_neg_mv;
 		st->vref_neg_mv = pdata->vref_neg_mv;
 	} else {
 		dev_warn(&spi->dev, "reference voltage unspecified\n");
 	}

 	ret = ad5791_spi_write(spi, AD5791_ADDR_SW_CTRL, AD5791_SWCTRL_RESET);
 	if (ret)
 		goto error_disable_reg_neg;

 	st->chip_info =	&ad5791_chip_info_tbl[spi_get_device_id(spi)
 					      ->driver_data];


 	st->ctrl = AD5761_CTRL_LINCOMP(st->chip_info->get_lin_comp(st->vref_mv))
 		  | ((pdata && pdata->use_rbuf_gain2) ? 0 : AD5791_CTRL_RBUF) |
 		  AD5791_CTRL_BIN2SC;

 	ret = ad5791_spi_write(spi, AD5791_ADDR_CTRL, st->ctrl |
 		AD5791_CTRL_OPGND | AD5791_CTRL_DACTRI);
 	if (ret)
 		goto error_disable_reg_neg;

 	spi_set_drvdata(spi, indio_dev);
 	indio_dev->dev.parent = &spi->dev;
 	indio_dev->info = &ad5791_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels
 		= &ad5791_channels[spi_get_device_id(spi)->driver_data];
 	indio_dev->num_channels = 1;
 	indio_dev->name = spi_get_device_id(st->spi)->name;
 	ret = iio_device_register(indio_dev);
 	if (ret)
 		goto error_disable_reg_neg;

 	return 0;

 error_disable_reg_neg:
 	if (!IS_ERR(st->reg_vss))
 		regulator_disable(st->reg_vss);
 error_put_reg_neg:
 	if (!IS_ERR(st->reg_vss))
 		regulator_put(st->reg_vss);

 	if (!IS_ERR(st->reg_vdd))
 		regulator_disable(st->reg_vdd);
 error_put_reg_pos:
 	if (!IS_ERR(st->reg_vdd))
 		regulator_put(st->reg_vdd);
 	iio_device_free(indio_dev);
 error_ret:

 	return ret;
 }

 static int __devexit ad5791_remove(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
 	struct ad5791_state *st = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);
 	if (!IS_ERR(st->reg_vdd)) {
 		regulator_disable(st->reg_vdd);
 		regulator_put(st->reg_vdd);
 	}

 	if (!IS_ERR(st->reg_vss)) {
 		regulator_disable(st->reg_vss);
 		regulator_put(st->reg_vss);
 	}
 	iio_device_free(indio_dev);

 	return 0;
 }

 static const struct spi_device_id ad5791_id[] = {
 	{"ad5760", ID_AD5760},
 	{"ad5780", ID_AD5780},
 	{"ad5781", ID_AD5781},
 	{"ad5790", ID_AD5791},
 	{"ad5791", ID_AD5791},
 	{}
 };
 MODULE_DEVICE_TABLE(spi, ad5791_id);

 static struct spi_driver ad5791_driver = {
 	.driver = {
 		   .name = "ad5791",
 		   .owner = THIS_MODULE,
 		   },
 	.probe = ad5791_probe,
 	.remove = __devexit_p(ad5791_remove),
 	.id_table = ad5791_id,
 };
 module_spi_driver(ad5791_driver);

 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 MODULE_DESCRIPTION("Analog Devices AD5760/AD5780/AD5781/AD5790/AD5791 DAC");
 MODULE_LICENSE("GPL v2");
	/*
	* AD5760, AD5780, AD5781, AD5790, AD5791 Voltage Output Digital to Analog
	* Converter
	*
	* Copyright 2011 Analog Devices Inc.
	*
	* Licensed under the GPL-2.
	*/

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

	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/iio/dac/ad5791.h>

	#define AD5791_RES_MASK(x) ((1 << (x)) - 1)
	#define AD5791_DAC_MASK AD5791_RES_MASK(20)
	#define AD5791_DAC_MSB (1 << 19)

	#define AD5791_CMD_READ (1 << 23)
	#define AD5791_CMD_WRITE (0 << 23)
	#define AD5791_ADDR(addr) ((addr) << 20)

	/* Registers */
	#define AD5791_ADDR_NOOP 0
	#define AD5791_ADDR_DAC0 1
	#define AD5791_ADDR_CTRL 2
	#define AD5791_ADDR_CLRCODE 3
	#define AD5791_ADDR_SW_CTRL 4

	/* Control Register */
	#define AD5791_CTRL_RBUF (1 << 1)
	#define AD5791_CTRL_OPGND (1 << 2)
	#define AD5791_CTRL_DACTRI (1 << 3)
	#define AD5791_CTRL_BIN2SC (1 << 4)
	#define AD5791_CTRL_SDODIS (1 << 5)
	#define AD5761_CTRL_LINCOMP(x) ((x) << 6)

	#define AD5791_LINCOMP_0_10 0
	#define AD5791_LINCOMP_10_12 1
	#define AD5791_LINCOMP_12_16 2
	#define AD5791_LINCOMP_16_19 3
	#define AD5791_LINCOMP_19_20 12

	#define AD5780_LINCOMP_0_10 0
	#define AD5780_LINCOMP_10_20 12

	/* Software Control Register */
	#define AD5791_SWCTRL_LDAC (1 << 0)
	#define AD5791_SWCTRL_CLR (1 << 1)
	#define AD5791_SWCTRL_RESET (1 << 2)

	#define AD5791_DAC_PWRDN_6K 0
	#define AD5791_DAC_PWRDN_3STATE 1

	/**
	* struct ad5791_chip_info - chip specific information
	* @get_lin_comp: function pointer to the device specific function
	*/

	struct ad5791_chip_info {
	int (*get_lin_comp) (unsigned int span);
	};

	/**
	* struct ad5791_state - driver instance specific data
	* @us: spi_device
	* @reg_vdd: positive supply regulator
	* @reg_vss: negative supply regulator
	* @chip_info: chip model specific constants
	* @vref_mv: actual reference voltage used
	* @vref_neg_mv: voltage of the negative supply
	* @pwr_down_mode current power down mode
	*/

	struct ad5791_state {
	struct spi_device *spi;
	struct regulator *reg_vdd;
	struct regulator *reg_vss;
	const struct ad5791_chip_info *chip_info;
	unsigned short vref_mv;
	unsigned int vref_neg_mv;
	unsigned ctrl;
	unsigned pwr_down_mode;
	bool pwr_down;
	};

	/**
	* ad5791_supported_device_ids:
	*/

	enum ad5791_supported_device_ids {
	ID_AD5760,
	ID_AD5780,
	ID_AD5781,
	ID_AD5791,
	};

	static int ad5791_spi_write(struct spi_device *spi, u8 addr, u32 val)
	{
	union {
	u32 d32;
	u8 d8[4];
	} data;

	data.d32 = cpu_to_be32(AD5791_CMD_WRITE \|
	AD5791_ADDR(addr) \|
	(val & AD5791_DAC_MASK));

	return spi_write(spi, &data.d8[1], 3);
	}

	static int ad5791_spi_read(struct spi_device spi, u8 addr, u32 val)
	{
	union {
	u32 d32;
	u8 d8[4];
	} data[3];
	int ret;
	struct spi_message msg;
	struct spi_transfer xfers[] = {
	{
	.tx_buf = &data[0].d8[1],
	.bits_per_word = 8,
	.len = 3,
	.cs_change = 1,
	}, {
	.tx_buf = &data[1].d8[1],
	.rx_buf = &data[2].d8[1],
	.bits_per_word = 8,
	.len = 3,
	},
	};

	data[0].d32 = cpu_to_be32(AD5791_CMD_READ \|
	AD5791_ADDR(addr));
	data[1].d32 = cpu_to_be32(AD5791_ADDR(AD5791_ADDR_NOOP));

	spi_message_init(&msg);
	spi_message_add_tail(&xfers[0], &msg);
	spi_message_add_tail(&xfers[1], &msg);
	ret = spi_sync(spi, &msg);

	*val = be32_to_cpu(data[2].d32);

	return ret;
	}

	static const char * const ad5791_powerdown_modes[] = {
	"6kohm_to_gnd",
	"three_state",
	};

	static int ad5791_get_powerdown_mode(struct iio_dev *indio_dev,
	const struct iio_chan_spec *chan)
	{
	struct ad5791_state *st = iio_priv(indio_dev);

	return st->pwr_down_mode;
	}

	static int ad5791_set_powerdown_mode(struct iio_dev *indio_dev,
	const struct iio_chan_spec *chan, unsigned int mode)
	{
	struct ad5791_state *st = iio_priv(indio_dev);

	st->pwr_down_mode = mode;

	return 0;
	}

	static const struct iio_enum ad5791_powerdown_mode_enum = {
	.items = ad5791_powerdown_modes,
	.num_items = ARRAY_SIZE(ad5791_powerdown_modes),
	.get = ad5791_get_powerdown_mode,
	.set = ad5791_set_powerdown_mode,
	};

	static ssize_t ad5791_read_dac_powerdown(struct iio_dev *indio_dev,
	uintptr_t private, const struct iio_chan_spec chan, char buf)
	{
	struct ad5791_state *st = iio_priv(indio_dev);

	return sprintf(buf, "%d\n", st->pwr_down);
	}

	static ssize_t ad5791_write_dac_powerdown(struct iio_dev *indio_dev,
	uintptr_t private, const struct iio_chan_spec chan, const char buf,
	size_t len)
	{
	bool pwr_down;
	int ret;
	struct ad5791_state *st = iio_priv(indio_dev);

	ret = strtobool(buf, &pwr_down);
	if (ret)
	return ret;

	if (!pwr_down) {
	st->ctrl &= ~(AD5791_CTRL_OPGND \| AD5791_CTRL_DACTRI);
	} else {
	if (st->pwr_down_mode == AD5791_DAC_PWRDN_6K)
	st->ctrl \|= AD5791_CTRL_OPGND;
	else if (st->pwr_down_mode == AD5791_DAC_PWRDN_3STATE)
	st->ctrl \|= AD5791_CTRL_DACTRI;
	}
	st->pwr_down = pwr_down;

	ret = ad5791_spi_write(st->spi, AD5791_ADDR_CTRL, st->ctrl);

	return ret ? ret : len;
	}

	static int ad5791_get_lin_comp(unsigned int span)
	{
	if (span <= 10000)
	return AD5791_LINCOMP_0_10;
	else if (span <= 12000)
	return AD5791_LINCOMP_10_12;
	else if (span <= 16000)
	return AD5791_LINCOMP_12_16;
	else if (span <= 19000)
	return AD5791_LINCOMP_16_19;
	else
	return AD5791_LINCOMP_19_20;
	}

	static int ad5780_get_lin_comp(unsigned int span)
	{
	if (span <= 10000)
	return AD5780_LINCOMP_0_10;
	else
	return AD5780_LINCOMP_10_20;
	}
	static const struct ad5791_chip_info ad5791_chip_info_tbl[] = {
	[ID_AD5760] = {
	.get_lin_comp = ad5780_get_lin_comp,
	},
	[ID_AD5780] = {
	.get_lin_comp = ad5780_get_lin_comp,
	},
	[ID_AD5781] = {
	.get_lin_comp = ad5791_get_lin_comp,
	},
	[ID_AD5791] = {
	.get_lin_comp = ad5791_get_lin_comp,
	},
	};

	static int ad5791_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int *val,
	int *val2,
	long m)
	{
	struct ad5791_state *st = iio_priv(indio_dev);
	u64 val64;
	int ret;

	switch (m) {
	case IIO_CHAN_INFO_RAW:
	ret = ad5791_spi_read(st->spi, chan->address, val);
	if (ret)
	return ret;
	*val &= AD5791_DAC_MASK;
	*val >>= chan->scan_type.shift;
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	*val = 0;
	val2 = (((u64)st->vref_mv) 1000000ULL) >> chan->scan_type.realbits;
	return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_OFFSET:
	val64 = (((u64)st->vref_neg_mv) << chan->scan_type.realbits);
	do_div(val64, st->vref_mv);
	*val = -val64;
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}

	};

	static const struct iio_chan_spec_ext_info ad5791_ext_info[] = {
	{
	.name = "powerdown",
	.shared = true,
	.read = ad5791_read_dac_powerdown,
	.write = ad5791_write_dac_powerdown,
	},
	IIO_ENUM("powerdown_mode", true, &ad5791_powerdown_mode_enum),
	IIO_ENUM_AVAILABLE("powerdown_mode", &ad5791_powerdown_mode_enum),
	{ },
	};

	#define AD5791_CHAN(bits, shift) { \
	.type = IIO_VOLTAGE, \
	.output = 1, \
	.indexed = 1, \
	.address = AD5791_ADDR_DAC0, \
	.channel = 0, \
	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT \| \
	IIO_CHAN_INFO_SCALE_SHARED_BIT \| \
	IIO_CHAN_INFO_OFFSET_SHARED_BIT, \
	.scan_type = IIO_ST('u', bits, 24, shift), \
	.ext_info = ad5791_ext_info, \
	}

	static const struct iio_chan_spec ad5791_channels[] = {
	[ID_AD5760] = AD5791_CHAN(16, 4),
	[ID_AD5780] = AD5791_CHAN(18, 2),
	[ID_AD5781] = AD5791_CHAN(18, 2),
	[ID_AD5791] = AD5791_CHAN(20, 0)
	};

	static int ad5791_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val,
	int val2,
	long mask)
	{
	struct ad5791_state *st = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	val &= AD5791_RES_MASK(chan->scan_type.realbits);
	val <<= chan->scan_type.shift;

	return ad5791_spi_write(st->spi, chan->address, val);

	default:
	return -EINVAL;
	}
	}

	static const struct iio_info ad5791_info = {
	.read_raw = &ad5791_read_raw,
	.write_raw = &ad5791_write_raw,
	.driver_module = THIS_MODULE,
	};

	static int __devinit ad5791_probe(struct spi_device *spi)
	{
	struct ad5791_platform_data *pdata = spi->dev.platform_data;
	struct iio_dev *indio_dev;
	struct ad5791_state *st;
	int ret, pos_voltage_uv = 0, neg_voltage_uv = 0;

	indio_dev = iio_device_alloc(sizeof(*st));
	if (indio_dev == NULL) {
	ret = -ENOMEM;
	goto error_ret;
	}
	st = iio_priv(indio_dev);
	st->reg_vdd = regulator_get(&spi->dev, "vdd");
	if (!IS_ERR(st->reg_vdd)) {
	ret = regulator_enable(st->reg_vdd);
	if (ret)
	goto error_put_reg_pos;

	pos_voltage_uv = regulator_get_voltage(st->reg_vdd);
	}

	st->reg_vss = regulator_get(&spi->dev, "vss");
	if (!IS_ERR(st->reg_vss)) {
	ret = regulator_enable(st->reg_vss);
	if (ret)
	goto error_put_reg_neg;

	neg_voltage_uv = regulator_get_voltage(st->reg_vss);
	}

	st->pwr_down = true;
	st->spi = spi;

	if (!IS_ERR(st->reg_vss) && !IS_ERR(st->reg_vdd)) {
	st->vref_mv = (pos_voltage_uv + neg_voltage_uv) / 1000;
	st->vref_neg_mv = neg_voltage_uv / 1000;
	} else if (pdata) {
	st->vref_mv = pdata->vref_pos_mv + pdata->vref_neg_mv;
	st->vref_neg_mv = pdata->vref_neg_mv;
	} else {
	dev_warn(&spi->dev, "reference voltage unspecified\n");
	}

	ret = ad5791_spi_write(spi, AD5791_ADDR_SW_CTRL, AD5791_SWCTRL_RESET);
	if (ret)
	goto error_disable_reg_neg;

	st->chip_info = &ad5791_chip_info_tbl[spi_get_device_id(spi)
	->driver_data];


	st->ctrl = AD5761_CTRL_LINCOMP(st->chip_info->get_lin_comp(st->vref_mv))
	\| ((pdata && pdata->use_rbuf_gain2) ? 0 : AD5791_CTRL_RBUF) \|
	AD5791_CTRL_BIN2SC;

	ret = ad5791_spi_write(spi, AD5791_ADDR_CTRL, st->ctrl \|
	AD5791_CTRL_OPGND \| AD5791_CTRL_DACTRI);
	if (ret)
	goto error_disable_reg_neg;

	spi_set_drvdata(spi, indio_dev);
	indio_dev->dev.parent = &spi->dev;
	indio_dev->info = &ad5791_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels
	= &ad5791_channels[spi_get_device_id(spi)->driver_data];
	indio_dev->num_channels = 1;
	indio_dev->name = spi_get_device_id(st->spi)->name;
	ret = iio_device_register(indio_dev);
	if (ret)
	goto error_disable_reg_neg;

	return 0;

	error_disable_reg_neg:
	if (!IS_ERR(st->reg_vss))
	regulator_disable(st->reg_vss);
	error_put_reg_neg:
	if (!IS_ERR(st->reg_vss))
	regulator_put(st->reg_vss);

	if (!IS_ERR(st->reg_vdd))
	regulator_disable(st->reg_vdd);
	error_put_reg_pos:
	if (!IS_ERR(st->reg_vdd))
	regulator_put(st->reg_vdd);
	iio_device_free(indio_dev);
	error_ret:

	return ret;
	}

	static int __devexit ad5791_remove(struct spi_device *spi)
	{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct ad5791_state *st = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	if (!IS_ERR(st->reg_vdd)) {
	regulator_disable(st->reg_vdd);
	regulator_put(st->reg_vdd);
	}

	if (!IS_ERR(st->reg_vss)) {
	regulator_disable(st->reg_vss);
	regulator_put(st->reg_vss);
	}
	iio_device_free(indio_dev);

	return 0;
	}

	static const struct spi_device_id ad5791_id[] = {
	{"ad5760", ID_AD5760},
	{"ad5780", ID_AD5780},
	{"ad5781", ID_AD5781},
	{"ad5790", ID_AD5791},
	{"ad5791", ID_AD5791},
	{}
	};
	MODULE_DEVICE_TABLE(spi, ad5791_id);

	static struct spi_driver ad5791_driver = {
	.driver = {
	.name = "ad5791",
	.owner = THIS_MODULE,
	},
	.probe = ad5791_probe,
	.remove = __devexit_p(ad5791_remove),
	.id_table = ad5791_id,
	};
	module_spi_driver(ad5791_driver);

	MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
	MODULE_DESCRIPTION("Analog Devices AD5760/AD5780/AD5781/AD5790/AD5791 DAC");
	MODULE_LICENSE("GPL v2");