drivers/staging/iio/dac/ad5791.c - kernel/mindspeed - Git at Google

 /*
  * AD5760, AD5780, AD5781, 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 "../iio.h"
 #include "../sysfs.h"
 #include "dac.h"
 #include "ad5791.h"

 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;
 }

 #define AD5791_CHAN(bits, shift) {			\
 	.type = IIO_VOLTAGE,				\
 	.output = 1,					\
 	.indexed = 1,					\
 	.address = AD5791_ADDR_DAC0,			\
 	.channel = 0,					\
 	.info_mask = (1 << IIO_CHAN_INFO_SCALE_SHARED) | \
 		(1 << IIO_CHAN_INFO_OFFSET_SHARED),	\
 	.scan_type = IIO_ST('u', bits, 24, shift)	\
 }

 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 ssize_t ad5791_read_powerdown_mode(struct device *dev,
 				      struct device_attribute *attr, char *buf)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct ad5791_state *st = iio_priv(indio_dev);

 	const char mode[][14] = {"6kohm_to_gnd", "three_state"};

 	return sprintf(buf, "%s\n", mode[st->pwr_down_mode]);
 }

 static ssize_t ad5791_write_powerdown_mode(struct device *dev,
 				       struct device_attribute *attr,
 				       const char *buf, size_t len)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct ad5791_state *st = iio_priv(indio_dev);
 	int ret;

 	if (sysfs_streq(buf, "6kohm_to_gnd"))
 		st->pwr_down_mode = AD5791_DAC_PWRDN_6K;
 	else if (sysfs_streq(buf, "three_state"))
 		st->pwr_down_mode = AD5791_DAC_PWRDN_3STATE;
 	else
 		ret = -EINVAL;

 	return ret ? ret : len;
 }

 static ssize_t ad5791_read_dac_powerdown(struct device *dev,
 					   struct device_attribute *attr,
 					   char *buf)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct ad5791_state *st = iio_priv(indio_dev);

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

 static ssize_t ad5791_write_dac_powerdown(struct device *dev,
 					    struct device_attribute *attr,
 					    const char *buf, size_t len)
 {
 	long readin;
 	int ret;
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	struct ad5791_state *st = iio_priv(indio_dev);

 	ret = strict_strtol(buf, 10, &readin);
 	if (ret)
 		return ret;

 	if (readin == 0) {
 		st->pwr_down = false;
 		st->ctrl &= ~(AD5791_CTRL_OPGND | AD5791_CTRL_DACTRI);
 	} else if (readin == 1) {
 		st->pwr_down = true;
 		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;
 	} else
 		ret = -EINVAL;

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

 	return ret ? ret : len;
 }

 static IIO_DEVICE_ATTR(out_voltage_powerdown_mode, S_IRUGO |
 			S_IWUSR, ad5791_read_powerdown_mode,
 			ad5791_write_powerdown_mode, 0);

 static IIO_CONST_ATTR(out_voltage_powerdown_mode_available,
 			"6kohm_to_gnd three_state");

 #define IIO_DEV_ATTR_DAC_POWERDOWN(_num, _show, _store, _addr)		\
 	IIO_DEVICE_ATTR(out_voltage##_num##_powerdown,			\
 			S_IRUGO | S_IWUSR, _show, _store, _addr)

 static IIO_DEV_ATTR_DAC_POWERDOWN(0, ad5791_read_dac_powerdown,
 				   ad5791_write_dac_powerdown, 0);

 static struct attribute *ad5791_attributes[] = {
 	&iio_dev_attr_out_voltage0_powerdown.dev_attr.attr,
 	&iio_dev_attr_out_voltage_powerdown_mode.dev_attr.attr,
 	&iio_const_attr_out_voltage_powerdown_mode_available.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group ad5791_attribute_group = {
 	.attrs = ad5791_attributes,
 };

 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 0:
 		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 (1 << IIO_CHAN_INFO_SCALE_SHARED):
 		*val = 0;
 		*val2 = (((u64)st->vref_mv) * 1000000ULL) >> chan->scan_type.realbits;
 		return IIO_VAL_INT_PLUS_MICRO;
 	case (1 << IIO_CHAN_INFO_OFFSET_SHARED):
 		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 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 0:
 		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,
 	.attrs = &ad5791_attribute_group,
 	.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_allocate_device(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_free_device(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_free_device(indio_dev);

 	return 0;
 }

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

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

 static __init int ad5791_spi_init(void)
 {
 	return spi_register_driver(&ad5791_driver);
 }
 module_init(ad5791_spi_init);

 static __exit void ad5791_spi_exit(void)
 {
 	spi_unregister_driver(&ad5791_driver);
 }
 module_exit(ad5791_spi_exit);

 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 MODULE_DESCRIPTION("Analog Devices AD5760/AD5780/AD5781/AD5791 DAC");
 MODULE_LICENSE("GPL v2");
	/*
	* AD5760, AD5780, AD5781, 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 "../iio.h"
	#include "../sysfs.h"
	#include "dac.h"
	#include "ad5791.h"

	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;
	}

	#define AD5791_CHAN(bits, shift) { \
	.type = IIO_VOLTAGE, \
	.output = 1, \
	.indexed = 1, \
	.address = AD5791_ADDR_DAC0, \
	.channel = 0, \
	.info_mask = (1 << IIO_CHAN_INFO_SCALE_SHARED) \| \
	(1 << IIO_CHAN_INFO_OFFSET_SHARED), \
	.scan_type = IIO_ST('u', bits, 24, shift) \
	}

	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 ssize_t ad5791_read_powerdown_mode(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad5791_state *st = iio_priv(indio_dev);

	const char mode[][14] = {"6kohm_to_gnd", "three_state"};

	return sprintf(buf, "%s\n", mode[st->pwr_down_mode]);
	}

	static ssize_t ad5791_write_powerdown_mode(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t len)
	{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad5791_state *st = iio_priv(indio_dev);
	int ret;

	if (sysfs_streq(buf, "6kohm_to_gnd"))
	st->pwr_down_mode = AD5791_DAC_PWRDN_6K;
	else if (sysfs_streq(buf, "three_state"))
	st->pwr_down_mode = AD5791_DAC_PWRDN_3STATE;
	else
	ret = -EINVAL;

	return ret ? ret : len;
	}

	static ssize_t ad5791_read_dac_powerdown(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad5791_state *st = iio_priv(indio_dev);

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

	static ssize_t ad5791_write_dac_powerdown(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t len)
	{
	long readin;
	int ret;
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad5791_state *st = iio_priv(indio_dev);

	ret = strict_strtol(buf, 10, &readin);
	if (ret)
	return ret;

	if (readin == 0) {
	st->pwr_down = false;
	st->ctrl &= ~(AD5791_CTRL_OPGND \| AD5791_CTRL_DACTRI);
	} else if (readin == 1) {
	st->pwr_down = true;
	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;
	} else
	ret = -EINVAL;

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

	return ret ? ret : len;
	}

	static IIO_DEVICE_ATTR(out_voltage_powerdown_mode, S_IRUGO \|
	S_IWUSR, ad5791_read_powerdown_mode,
	ad5791_write_powerdown_mode, 0);

	static IIO_CONST_ATTR(out_voltage_powerdown_mode_available,
	"6kohm_to_gnd three_state");

	#define IIO_DEV_ATTR_DAC_POWERDOWN(_num, _show, _store, _addr) \
	IIO_DEVICE_ATTR(out_voltage##_num##_powerdown, \
	S_IRUGO \| S_IWUSR, _show, _store, _addr)

	static IIO_DEV_ATTR_DAC_POWERDOWN(0, ad5791_read_dac_powerdown,
	ad5791_write_dac_powerdown, 0);

	static struct attribute *ad5791_attributes[] = {
	&iio_dev_attr_out_voltage0_powerdown.dev_attr.attr,
	&iio_dev_attr_out_voltage_powerdown_mode.dev_attr.attr,
	&iio_const_attr_out_voltage_powerdown_mode_available.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group ad5791_attribute_group = {
	.attrs = ad5791_attributes,
	};

	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 0:
	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 (1 << IIO_CHAN_INFO_SCALE_SHARED):
	*val = 0;
	val2 = (((u64)st->vref_mv) 1000000ULL) >> chan->scan_type.realbits;
	return IIO_VAL_INT_PLUS_MICRO;
	case (1 << IIO_CHAN_INFO_OFFSET_SHARED):
	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 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 0:
	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,
	.attrs = &ad5791_attribute_group,
	.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_allocate_device(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_free_device(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_free_device(indio_dev);

	return 0;
	}

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

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

	static __init int ad5791_spi_init(void)
	{
	return spi_register_driver(&ad5791_driver);
	}
	module_init(ad5791_spi_init);

	static __exit void ad5791_spi_exit(void)
	{
	spi_unregister_driver(&ad5791_driver);
	}
	module_exit(ad5791_spi_exit);

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