drivers/iio/dac/ad5755.c - kernel/msm-4.9 - Gitiles

 /*
  * AD5755, AD5755-1, AD5757, AD5735, AD5737 Digital to analog converters driver
  *
  * Copyright 2012 Analog Devices Inc.
  *
  * Licensed under the GPL-2.
  */

 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/spi/spi.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/delay.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/platform_data/ad5755.h>

 #define AD5755_NUM_CHANNELS 4

 #define AD5755_ADDR(x)			((x) << 16)

 #define AD5755_WRITE_REG_DATA(chan)	(chan)
 #define AD5755_WRITE_REG_GAIN(chan)	(0x08 | (chan))
 #define AD5755_WRITE_REG_OFFSET(chan)	(0x10 | (chan))
 #define AD5755_WRITE_REG_CTRL(chan)	(0x1c | (chan))

 #define AD5755_READ_REG_DATA(chan)	(chan)
 #define AD5755_READ_REG_CTRL(chan)	(0x4 | (chan))
 #define AD5755_READ_REG_GAIN(chan)	(0x8 | (chan))
 #define AD5755_READ_REG_OFFSET(chan)	(0xc | (chan))
 #define AD5755_READ_REG_CLEAR(chan)	(0x10 | (chan))
 #define AD5755_READ_REG_SLEW(chan)	(0x14 | (chan))
 #define AD5755_READ_REG_STATUS		0x18
 #define AD5755_READ_REG_MAIN		0x19
 #define AD5755_READ_REG_DC_DC		0x1a

 #define AD5755_CTRL_REG_SLEW	0x0
 #define AD5755_CTRL_REG_MAIN	0x1
 #define AD5755_CTRL_REG_DAC	0x2
 #define AD5755_CTRL_REG_DC_DC	0x3
 #define AD5755_CTRL_REG_SW	0x4

 #define AD5755_READ_FLAG 0x800000

 #define AD5755_NOOP 0x1CE000

 #define AD5755_DAC_INT_EN			BIT(8)
 #define AD5755_DAC_CLR_EN			BIT(7)
 #define AD5755_DAC_OUT_EN			BIT(6)
 #define AD5755_DAC_INT_CURRENT_SENSE_RESISTOR	BIT(5)
 #define AD5755_DAC_DC_DC_EN			BIT(4)
 #define AD5755_DAC_VOLTAGE_OVERRANGE_EN		BIT(3)

 #define AD5755_DC_DC_MAXV			0
 #define AD5755_DC_DC_FREQ_SHIFT			2
 #define AD5755_DC_DC_PHASE_SHIFT		4
 #define AD5755_EXT_DC_DC_COMP_RES		BIT(6)

 #define AD5755_SLEW_STEP_SIZE_SHIFT		0
 #define AD5755_SLEW_RATE_SHIFT			3
 #define AD5755_SLEW_ENABLE			BIT(12)

 /**
  * struct ad5755_chip_info - chip specific information
  * @channel_template:	channel specification
  * @calib_shift:	shift for the calibration data registers
  * @has_voltage_out:	whether the chip has voltage outputs
  */
 struct ad5755_chip_info {
 	const struct iio_chan_spec channel_template;
 	unsigned int calib_shift;
 	bool has_voltage_out;
 };

 /**
  * struct ad5755_state - driver instance specific data
  * @spi:	spi device the driver is attached to
  * @chip_info:	chip model specific constants, available modes etc
  * @pwr_down:	bitmask which contains  hether a channel is powered down or not
  * @ctrl:	software shadow of the channel ctrl registers
  * @channels:	iio channel spec for the device
  * @data:	spi transfer buffers
  */
 struct ad5755_state {
 	struct spi_device		*spi;
 	const struct ad5755_chip_info	*chip_info;
 	unsigned int			pwr_down;
 	unsigned int			ctrl[AD5755_NUM_CHANNELS];
 	struct iio_chan_spec		channels[AD5755_NUM_CHANNELS];

 	/*
 	 * DMA (thus cache coherency maintenance) requires the
 	 * transfer buffers to live in their own cache lines.
 	 */

 	union {
 		u32 d32;
 		u8 d8[4];
 	} data[2] ____cacheline_aligned;
 };

 enum ad5755_type {
 	ID_AD5755,
 	ID_AD5757,
 	ID_AD5735,
 	ID_AD5737,
 };

 static int ad5755_write_unlocked(struct iio_dev *indio_dev,
 	unsigned int reg, unsigned int val)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);

 	st->data[0].d32 = cpu_to_be32((reg << 16) | val);

 	return spi_write(st->spi, &st->data[0].d8[1], 3);
 }

 static int ad5755_write_ctrl_unlocked(struct iio_dev *indio_dev,
 	unsigned int channel, unsigned int reg, unsigned int val)
 {
 	return ad5755_write_unlocked(indio_dev,
 		AD5755_WRITE_REG_CTRL(channel), (reg << 13) | val);
 }

 static int ad5755_write(struct iio_dev *indio_dev, unsigned int reg,
 	unsigned int val)
 {
 	int ret;

 	mutex_lock(&indio_dev->mlock);
 	ret = ad5755_write_unlocked(indio_dev, reg, val);
 	mutex_unlock(&indio_dev->mlock);

 	return ret;
 }

 static int ad5755_write_ctrl(struct iio_dev *indio_dev, unsigned int channel,
 	unsigned int reg, unsigned int val)
 {
 	int ret;

 	mutex_lock(&indio_dev->mlock);
 	ret = ad5755_write_ctrl_unlocked(indio_dev, channel, reg, val);
 	mutex_unlock(&indio_dev->mlock);

 	return ret;
 }

 static int ad5755_read(struct iio_dev *indio_dev, unsigned int addr)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);
 	struct spi_message m;
 	int ret;
 	struct spi_transfer t[] = {
 		{
 			.tx_buf = &st->data[0].d8[1],
 			.len = 3,
 			.cs_change = 1,
 		}, {
 			.tx_buf = &st->data[1].d8[1],
 			.rx_buf = &st->data[1].d8[1],
 			.len = 3,
 		},
 	};

 	spi_message_init(&m);
 	spi_message_add_tail(&t[0], &m);
 	spi_message_add_tail(&t[1], &m);

 	mutex_lock(&indio_dev->mlock);

 	st->data[0].d32 = cpu_to_be32(AD5755_READ_FLAG | (addr << 16));
 	st->data[1].d32 = cpu_to_be32(AD5755_NOOP);

 	ret = spi_sync(st->spi, &m);
 	if (ret >= 0)
 		ret = be32_to_cpu(st->data[1].d32) & 0xffff;

 	mutex_unlock(&indio_dev->mlock);

 	return ret;
 }

 static int ad5755_update_dac_ctrl(struct iio_dev *indio_dev,
 	unsigned int channel, unsigned int set, unsigned int clr)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);
 	int ret;

 	st->ctrl[channel] |= set;
 	st->ctrl[channel] &= ~clr;

 	ret = ad5755_write_ctrl_unlocked(indio_dev, channel,
 		AD5755_CTRL_REG_DAC, st->ctrl[channel]);

 	return ret;
 }

 static int ad5755_set_channel_pwr_down(struct iio_dev *indio_dev,
 	unsigned int channel, bool pwr_down)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);
 	unsigned int mask = BIT(channel);

 	mutex_lock(&indio_dev->mlock);

 	if ((bool)(st->pwr_down & mask) == pwr_down)
 		goto out_unlock;

 	if (!pwr_down) {
 		st->pwr_down &= ~mask;
 		ad5755_update_dac_ctrl(indio_dev, channel,
 			AD5755_DAC_INT_EN | AD5755_DAC_DC_DC_EN, 0);
 		udelay(200);
 		ad5755_update_dac_ctrl(indio_dev, channel,
 			AD5755_DAC_OUT_EN, 0);
 	} else {
 		st->pwr_down |= mask;
 		ad5755_update_dac_ctrl(indio_dev, channel,
 			0, AD5755_DAC_INT_EN | AD5755_DAC_OUT_EN |
 				AD5755_DAC_DC_DC_EN);
 	}

 out_unlock:
 	mutex_unlock(&indio_dev->mlock);

 	return 0;
 }

 static const int ad5755_min_max_table[][2] = {
 	[AD5755_MODE_VOLTAGE_0V_5V] = { 0, 5000 },
 	[AD5755_MODE_VOLTAGE_0V_10V] = { 0, 10000 },
 	[AD5755_MODE_VOLTAGE_PLUSMINUS_5V] = { -5000, 5000 },
 	[AD5755_MODE_VOLTAGE_PLUSMINUS_10V] = { -10000, 10000 },
 	[AD5755_MODE_CURRENT_4mA_20mA] = { 4, 20 },
 	[AD5755_MODE_CURRENT_0mA_20mA] = { 0, 20 },
 	[AD5755_MODE_CURRENT_0mA_24mA] = { 0, 24 },
 };

 static void ad5755_get_min_max(struct ad5755_state *st,
 	struct iio_chan_spec const *chan, int *min, int *max)
 {
 	enum ad5755_mode mode = st->ctrl[chan->channel] & 7;
 	*min = ad5755_min_max_table[mode][0];
 	*max = ad5755_min_max_table[mode][1];
 }

 static inline int ad5755_get_offset(struct ad5755_state *st,
 	struct iio_chan_spec const *chan)
 {
 	int min, max;

 	ad5755_get_min_max(st, chan, &min, &max);
 	return (min * (1 << chan->scan_type.realbits)) / (max - min);
 }

 static inline int ad5755_get_scale(struct ad5755_state *st,
 	struct iio_chan_spec const *chan)
 {
 	int min, max;

 	ad5755_get_min_max(st, chan, &min, &max);
 	return ((max - min) * 1000000000ULL) >> chan->scan_type.realbits;
 }

 static int ad5755_chan_reg_info(struct ad5755_state *st,
 	struct iio_chan_spec const *chan, long info, bool write,
 	unsigned int *reg, unsigned int *shift, unsigned int *offset)
 {
 	switch (info) {
 	case IIO_CHAN_INFO_RAW:
 		if (write)
 			*reg = AD5755_WRITE_REG_DATA(chan->address);
 		else
 			*reg = AD5755_READ_REG_DATA(chan->address);
 		*shift = chan->scan_type.shift;
 		*offset = 0;
 		break;
 	case IIO_CHAN_INFO_CALIBBIAS:
 		if (write)
 			*reg = AD5755_WRITE_REG_OFFSET(chan->address);
 		else
 			*reg = AD5755_READ_REG_OFFSET(chan->address);
 		*shift = st->chip_info->calib_shift;
 		*offset = 32768;
 		break;
 	case IIO_CHAN_INFO_CALIBSCALE:
 		if (write)
 			*reg =  AD5755_WRITE_REG_GAIN(chan->address);
 		else
 			*reg =  AD5755_READ_REG_GAIN(chan->address);
 		*shift = st->chip_info->calib_shift;
 		*offset = 0;
 		break;
 	default:
 		return -EINVAL;
 	}

 	return 0;
 }

 static int ad5755_read_raw(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, int *val, int *val2, long info)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);
 	unsigned int reg, shift, offset;
 	int ret;

 	switch (info) {
 	case IIO_CHAN_INFO_SCALE:
 		*val = 0;
 		*val2 = ad5755_get_scale(st, chan);
 		return IIO_VAL_INT_PLUS_NANO;
 	case IIO_CHAN_INFO_OFFSET:
 		*val = ad5755_get_offset(st, chan);
 		return IIO_VAL_INT;
 	default:
 		ret = ad5755_chan_reg_info(st, chan, info, false,
 						&reg, &shift, &offset);
 		if (ret)
 			return ret;

 		ret = ad5755_read(indio_dev, reg);
 		if (ret < 0)
 			return ret;

 		*val = (ret - offset) >> shift;

 		return IIO_VAL_INT;
 	}

 	return -EINVAL;
 }

 static int ad5755_write_raw(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, int val, int val2, long info)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);
 	unsigned int shift, reg, offset;
 	int ret;

 	ret = ad5755_chan_reg_info(st, chan, info, true,
 					&reg, &shift, &offset);
 	if (ret)
 		return ret;

 	val <<= shift;
 	val += offset;

 	if (val < 0 || val > 0xffff)
 		return -EINVAL;

 	return ad5755_write(indio_dev, reg, val);
 }

 static ssize_t ad5755_read_powerdown(struct iio_dev *indio_dev, uintptr_t priv,
 	const struct iio_chan_spec *chan, char *buf)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);

 	return sprintf(buf, "%d\n",
 		       (bool)(st->pwr_down & (1 << chan->channel)));
 }

 static ssize_t ad5755_write_powerdown(struct iio_dev *indio_dev, uintptr_t priv,
 	struct iio_chan_spec const *chan, const char *buf, size_t len)
 {
 	bool pwr_down;
 	int ret;

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

 	ret = ad5755_set_channel_pwr_down(indio_dev, chan->channel, pwr_down);
 	return ret ? ret : len;
 }

 static const struct iio_info ad5755_info = {
 	.read_raw = ad5755_read_raw,
 	.write_raw = ad5755_write_raw,
 	.driver_module = THIS_MODULE,
 };

 static const struct iio_chan_spec_ext_info ad5755_ext_info[] = {
 	{
 		.name = "powerdown",
 		.read = ad5755_read_powerdown,
 		.write = ad5755_write_powerdown,
 	},
 	{ },
 };

 #define AD5755_CHANNEL(_bits) {					\
 	.indexed = 1,						\
 	.output = 1,						\
 	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |		\
 		IIO_CHAN_INFO_SCALE_SEPARATE_BIT |		\
 		IIO_CHAN_INFO_OFFSET_SEPARATE_BIT |		\
 		IIO_CHAN_INFO_CALIBSCALE_SEPARATE_BIT |		\
 		IIO_CHAN_INFO_CALIBBIAS_SEPARATE_BIT,		\
 	.scan_type = IIO_ST('u', (_bits), 16, 16 - (_bits)),	\
 	.ext_info = ad5755_ext_info,				\
 }

 static const struct ad5755_chip_info ad5755_chip_info_tbl[] = {
 	[ID_AD5735] = {
 		.channel_template = AD5755_CHANNEL(14),
 		.has_voltage_out = true,
 		.calib_shift = 4,
 	},
 	[ID_AD5737] = {
 		.channel_template = AD5755_CHANNEL(14),
 		.has_voltage_out = false,
 		.calib_shift = 4,
 	},
 	[ID_AD5755] = {
 		.channel_template = AD5755_CHANNEL(16),
 		.has_voltage_out = true,
 		.calib_shift = 0,
 	},
 	[ID_AD5757] = {
 		.channel_template = AD5755_CHANNEL(16),
 		.has_voltage_out = false,
 		.calib_shift = 0,
 	},
 };

 static bool ad5755_is_valid_mode(struct ad5755_state *st, enum ad5755_mode mode)
 {
 	switch (mode) {
 	case AD5755_MODE_VOLTAGE_0V_5V:
 	case AD5755_MODE_VOLTAGE_0V_10V:
 	case AD5755_MODE_VOLTAGE_PLUSMINUS_5V:
 	case AD5755_MODE_VOLTAGE_PLUSMINUS_10V:
 		return st->chip_info->has_voltage_out;
 	case AD5755_MODE_CURRENT_4mA_20mA:
 	case AD5755_MODE_CURRENT_0mA_20mA:
 	case AD5755_MODE_CURRENT_0mA_24mA:
 		return true;
 	default:
 		return false;
 	}
 }

 static int __devinit ad5755_setup_pdata(struct iio_dev *indio_dev,
 	const struct ad5755_platform_data *pdata)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);
 	unsigned int val;
 	unsigned int i;
 	int ret;

 	if (pdata->dc_dc_phase > AD5755_DC_DC_PHASE_90_DEGREE ||
 		pdata->dc_dc_freq > AD5755_DC_DC_FREQ_650kHZ ||
 		pdata->dc_dc_maxv > AD5755_DC_DC_MAXV_29V5)
 		return -EINVAL;

 	val = pdata->dc_dc_maxv << AD5755_DC_DC_MAXV;
 	val |= pdata->dc_dc_freq << AD5755_DC_DC_FREQ_SHIFT;
 	val |= pdata->dc_dc_phase << AD5755_DC_DC_PHASE_SHIFT;
 	if (pdata->ext_dc_dc_compenstation_resistor)
 		val |= AD5755_EXT_DC_DC_COMP_RES;

 	ret = ad5755_write_ctrl(indio_dev, 0, AD5755_CTRL_REG_DC_DC, val);
 	if (ret < 0)
 		return ret;

 	for (i = 0; i < ARRAY_SIZE(pdata->dac); ++i) {
 		val = pdata->dac[i].slew.step_size <<
 			AD5755_SLEW_STEP_SIZE_SHIFT;
 		val |= pdata->dac[i].slew.rate <<
 			AD5755_SLEW_RATE_SHIFT;
 		if (pdata->dac[i].slew.enable)
 			val |= AD5755_SLEW_ENABLE;

 		ret = ad5755_write_ctrl(indio_dev, i,
 					AD5755_CTRL_REG_SLEW, val);
 		if (ret < 0)
 			return ret;
 	}

 	for (i = 0; i < ARRAY_SIZE(pdata->dac); ++i) {
 		if (!ad5755_is_valid_mode(st, pdata->dac[i].mode))
 			return -EINVAL;

 		val = 0;
 		if (!pdata->dac[i].ext_current_sense_resistor)
 			val |= AD5755_DAC_INT_CURRENT_SENSE_RESISTOR;
 		if (pdata->dac[i].enable_voltage_overrange)
 			val |= AD5755_DAC_VOLTAGE_OVERRANGE_EN;
 		val |= pdata->dac[i].mode;

 		ret = ad5755_update_dac_ctrl(indio_dev, i, val, 0);
 		if (ret < 0)
 			return ret;
 	}

 	return 0;
 }

 static bool __devinit ad5755_is_voltage_mode(enum ad5755_mode mode)
 {
 	switch (mode) {
 	case AD5755_MODE_VOLTAGE_0V_5V:
 	case AD5755_MODE_VOLTAGE_0V_10V:
 	case AD5755_MODE_VOLTAGE_PLUSMINUS_5V:
 	case AD5755_MODE_VOLTAGE_PLUSMINUS_10V:
 		return true;
 	default:
 		return false;
 	}
 }

 static int __devinit ad5755_init_channels(struct iio_dev *indio_dev,
 	const struct ad5755_platform_data *pdata)
 {
 	struct ad5755_state *st = iio_priv(indio_dev);
 	struct iio_chan_spec *channels = st->channels;
 	unsigned int i;

 	for (i = 0; i < AD5755_NUM_CHANNELS; ++i) {
 		channels[i] = st->chip_info->channel_template;
 		channels[i].channel = i;
 		channels[i].address = i;
 		if (pdata && ad5755_is_voltage_mode(pdata->dac[i].mode))
 			channels[i].type = IIO_VOLTAGE;
 		else
 			channels[i].type = IIO_CURRENT;
 	}

 	indio_dev->channels = channels;

 	return 0;
 }

 #define AD5755_DEFAULT_DAC_PDATA { \
 		.mode = AD5755_MODE_CURRENT_4mA_20mA, \
 		.ext_current_sense_resistor = true, \
 		.enable_voltage_overrange = false, \
 		.slew = { \
 			.enable = false, \
 			.rate = AD5755_SLEW_RATE_64k, \
 			.step_size = AD5755_SLEW_STEP_SIZE_1, \
 		}, \
 	}

 static const struct ad5755_platform_data ad5755_default_pdata = {
 	.ext_dc_dc_compenstation_resistor = false,
 	.dc_dc_phase = AD5755_DC_DC_PHASE_ALL_SAME_EDGE,
 	.dc_dc_freq = AD5755_DC_DC_FREQ_410kHZ,
 	.dc_dc_maxv = AD5755_DC_DC_MAXV_23V,
 	.dac = {
 		[0] = AD5755_DEFAULT_DAC_PDATA,
 		[1] = AD5755_DEFAULT_DAC_PDATA,
 		[2] = AD5755_DEFAULT_DAC_PDATA,
 		[3] = AD5755_DEFAULT_DAC_PDATA,
 	},
 };

 static int __devinit ad5755_probe(struct spi_device *spi)
 {
 	enum ad5755_type type = spi_get_device_id(spi)->driver_data;
 	const struct ad5755_platform_data *pdata = dev_get_platdata(&spi->dev);
 	struct iio_dev *indio_dev;
 	struct ad5755_state *st;
 	int ret;

 	indio_dev = iio_device_alloc(sizeof(*st));
 	if (indio_dev == NULL) {
 		dev_err(&spi->dev, "Failed to allocate iio device\n");
 		return  -ENOMEM;
 	}

 	st = iio_priv(indio_dev);
 	spi_set_drvdata(spi, indio_dev);

 	st->chip_info = &ad5755_chip_info_tbl[type];
 	st->spi = spi;
 	st->pwr_down = 0xf;

 	indio_dev->dev.parent = &spi->dev;
 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->info = &ad5755_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->num_channels = AD5755_NUM_CHANNELS;

 	if (!pdata)
 		pdata = &ad5755_default_pdata;

 	ret = ad5755_init_channels(indio_dev, pdata);
 	if (ret)
 		goto error_free;

 	ret = ad5755_setup_pdata(indio_dev, pdata);
 	if (ret)
 		goto error_free;

 	ret = iio_device_register(indio_dev);
 	if (ret) {
 		dev_err(&spi->dev, "Failed to register iio device: %d\n", ret);
 		goto error_free;
 	}

 	return 0;

 error_free:
 	iio_device_free(indio_dev);

 	return ret;
 }

 static int __devexit ad5755_remove(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev = spi_get_drvdata(spi);

 	iio_device_unregister(indio_dev);
 	iio_device_free(indio_dev);

 	return 0;
 }

 static const struct spi_device_id ad5755_id[] = {
 	{ "ad5755", ID_AD5755 },
 	{ "ad5755-1", ID_AD5755 },
 	{ "ad5757", ID_AD5757 },
 	{ "ad5735", ID_AD5735 },
 	{ "ad5737", ID_AD5737 },
 	{}
 };
 MODULE_DEVICE_TABLE(spi, ad5755_id);

 static struct spi_driver ad5755_driver = {
 	.driver = {
 		.name = "ad5755",
 		.owner = THIS_MODULE,
 	},
 	.probe = ad5755_probe,
 	.remove = __devexit_p(ad5755_remove),
 	.id_table = ad5755_id,
 };
 module_spi_driver(ad5755_driver);

 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 MODULE_DESCRIPTION("Analog Devices AD5755/55-1/57/35/37 DAC");
 MODULE_LICENSE("GPL v2");
	/*
	* AD5755, AD5755-1, AD5757, AD5735, AD5737 Digital to analog converters driver
	*
	* Copyright 2012 Analog Devices Inc.
	*
	* Licensed under the GPL-2.
	*/

	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/spi/spi.h>
	#include <linux/slab.h>
	#include <linux/sysfs.h>
	#include <linux/delay.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/platform_data/ad5755.h>

	#define AD5755_NUM_CHANNELS 4

	#define AD5755_ADDR(x) ((x) << 16)

	#define AD5755_WRITE_REG_DATA(chan) (chan)
	#define AD5755_WRITE_REG_GAIN(chan) (0x08 \| (chan))
	#define AD5755_WRITE_REG_OFFSET(chan) (0x10 \| (chan))
	#define AD5755_WRITE_REG_CTRL(chan) (0x1c \| (chan))

	#define AD5755_READ_REG_DATA(chan) (chan)
	#define AD5755_READ_REG_CTRL(chan) (0x4 \| (chan))
	#define AD5755_READ_REG_GAIN(chan) (0x8 \| (chan))
	#define AD5755_READ_REG_OFFSET(chan) (0xc \| (chan))
	#define AD5755_READ_REG_CLEAR(chan) (0x10 \| (chan))
	#define AD5755_READ_REG_SLEW(chan) (0x14 \| (chan))
	#define AD5755_READ_REG_STATUS 0x18
	#define AD5755_READ_REG_MAIN 0x19
	#define AD5755_READ_REG_DC_DC 0x1a

	#define AD5755_CTRL_REG_SLEW 0x0
	#define AD5755_CTRL_REG_MAIN 0x1
	#define AD5755_CTRL_REG_DAC 0x2
	#define AD5755_CTRL_REG_DC_DC 0x3
	#define AD5755_CTRL_REG_SW 0x4

	#define AD5755_READ_FLAG 0x800000

	#define AD5755_NOOP 0x1CE000

	#define AD5755_DAC_INT_EN BIT(8)
	#define AD5755_DAC_CLR_EN BIT(7)
	#define AD5755_DAC_OUT_EN BIT(6)
	#define AD5755_DAC_INT_CURRENT_SENSE_RESISTOR BIT(5)
	#define AD5755_DAC_DC_DC_EN BIT(4)
	#define AD5755_DAC_VOLTAGE_OVERRANGE_EN BIT(3)

	#define AD5755_DC_DC_MAXV 0
	#define AD5755_DC_DC_FREQ_SHIFT 2
	#define AD5755_DC_DC_PHASE_SHIFT 4
	#define AD5755_EXT_DC_DC_COMP_RES BIT(6)

	#define AD5755_SLEW_STEP_SIZE_SHIFT 0
	#define AD5755_SLEW_RATE_SHIFT 3
	#define AD5755_SLEW_ENABLE BIT(12)

	/**
	* struct ad5755_chip_info - chip specific information
	* @channel_template: channel specification
	* @calib_shift: shift for the calibration data registers
	* @has_voltage_out: whether the chip has voltage outputs
	*/
	struct ad5755_chip_info {
	const struct iio_chan_spec channel_template;
	unsigned int calib_shift;
	bool has_voltage_out;
	};

	/**
	* struct ad5755_state - driver instance specific data
	* @spi: spi device the driver is attached to
	* @chip_info: chip model specific constants, available modes etc
	* @pwr_down: bitmask which contains hether a channel is powered down or not
	* @ctrl: software shadow of the channel ctrl registers
	* @channels: iio channel spec for the device
	* @data: spi transfer buffers
	*/
	struct ad5755_state {
	struct spi_device *spi;
	const struct ad5755_chip_info *chip_info;
	unsigned int pwr_down;
	unsigned int ctrl[AD5755_NUM_CHANNELS];
	struct iio_chan_spec channels[AD5755_NUM_CHANNELS];

	/*
	* DMA (thus cache coherency maintenance) requires the
	* transfer buffers to live in their own cache lines.
	*/

	union {
	u32 d32;
	u8 d8[4];
	} data[2] ____cacheline_aligned;
	};

	enum ad5755_type {
	ID_AD5755,
	ID_AD5757,
	ID_AD5735,
	ID_AD5737,
	};

	static int ad5755_write_unlocked(struct iio_dev *indio_dev,
	unsigned int reg, unsigned int val)
	{
	struct ad5755_state *st = iio_priv(indio_dev);

	st->data[0].d32 = cpu_to_be32((reg << 16) \| val);

	return spi_write(st->spi, &st->data[0].d8[1], 3);
	}

	static int ad5755_write_ctrl_unlocked(struct iio_dev *indio_dev,
	unsigned int channel, unsigned int reg, unsigned int val)
	{
	return ad5755_write_unlocked(indio_dev,
	AD5755_WRITE_REG_CTRL(channel), (reg << 13) \| val);
	}

	static int ad5755_write(struct iio_dev *indio_dev, unsigned int reg,
	unsigned int val)
	{
	int ret;

	mutex_lock(&indio_dev->mlock);
	ret = ad5755_write_unlocked(indio_dev, reg, val);
	mutex_unlock(&indio_dev->mlock);

	return ret;
	}

	static int ad5755_write_ctrl(struct iio_dev *indio_dev, unsigned int channel,
	unsigned int reg, unsigned int val)
	{
	int ret;

	mutex_lock(&indio_dev->mlock);
	ret = ad5755_write_ctrl_unlocked(indio_dev, channel, reg, val);
	mutex_unlock(&indio_dev->mlock);

	return ret;
	}

	static int ad5755_read(struct iio_dev *indio_dev, unsigned int addr)
	{
	struct ad5755_state *st = iio_priv(indio_dev);
	struct spi_message m;
	int ret;
	struct spi_transfer t[] = {
	{
	.tx_buf = &st->data[0].d8[1],
	.len = 3,
	.cs_change = 1,
	}, {
	.tx_buf = &st->data[1].d8[1],
	.rx_buf = &st->data[1].d8[1],
	.len = 3,
	},
	};

	spi_message_init(&m);
	spi_message_add_tail(&t[0], &m);
	spi_message_add_tail(&t[1], &m);

	mutex_lock(&indio_dev->mlock);

	st->data[0].d32 = cpu_to_be32(AD5755_READ_FLAG \| (addr << 16));
	st->data[1].d32 = cpu_to_be32(AD5755_NOOP);

	ret = spi_sync(st->spi, &m);
	if (ret >= 0)
	ret = be32_to_cpu(st->data[1].d32) & 0xffff;

	mutex_unlock(&indio_dev->mlock);

	return ret;
	}

	static int ad5755_update_dac_ctrl(struct iio_dev *indio_dev,
	unsigned int channel, unsigned int set, unsigned int clr)
	{
	struct ad5755_state *st = iio_priv(indio_dev);
	int ret;

	st->ctrl[channel] \|= set;
	st->ctrl[channel] &= ~clr;

	ret = ad5755_write_ctrl_unlocked(indio_dev, channel,
	AD5755_CTRL_REG_DAC, st->ctrl[channel]);

	return ret;
	}

	static int ad5755_set_channel_pwr_down(struct iio_dev *indio_dev,
	unsigned int channel, bool pwr_down)
	{
	struct ad5755_state *st = iio_priv(indio_dev);
	unsigned int mask = BIT(channel);

	mutex_lock(&indio_dev->mlock);

	if ((bool)(st->pwr_down & mask) == pwr_down)
	goto out_unlock;

	if (!pwr_down) {
	st->pwr_down &= ~mask;
	ad5755_update_dac_ctrl(indio_dev, channel,
	AD5755_DAC_INT_EN \| AD5755_DAC_DC_DC_EN, 0);
	udelay(200);
	ad5755_update_dac_ctrl(indio_dev, channel,
	AD5755_DAC_OUT_EN, 0);
	} else {
	st->pwr_down \|= mask;
	ad5755_update_dac_ctrl(indio_dev, channel,
	0, AD5755_DAC_INT_EN \| AD5755_DAC_OUT_EN \|
	AD5755_DAC_DC_DC_EN);
	}

	out_unlock:
	mutex_unlock(&indio_dev->mlock);

	return 0;
	}

	static const int ad5755_min_max_table[][2] = {
	[AD5755_MODE_VOLTAGE_0V_5V] = { 0, 5000 },
	[AD5755_MODE_VOLTAGE_0V_10V] = { 0, 10000 },
	[AD5755_MODE_VOLTAGE_PLUSMINUS_5V] = { -5000, 5000 },
	[AD5755_MODE_VOLTAGE_PLUSMINUS_10V] = { -10000, 10000 },
	[AD5755_MODE_CURRENT_4mA_20mA] = { 4, 20 },
	[AD5755_MODE_CURRENT_0mA_20mA] = { 0, 20 },
	[AD5755_MODE_CURRENT_0mA_24mA] = { 0, 24 },
	};

	static void ad5755_get_min_max(struct ad5755_state *st,
	struct iio_chan_spec const chan, int min, int *max)
	{
	enum ad5755_mode mode = st->ctrl[chan->channel] & 7;
	*min = ad5755_min_max_table[mode][0];
	*max = ad5755_min_max_table[mode][1];
	}

	static inline int ad5755_get_offset(struct ad5755_state *st,
	struct iio_chan_spec const *chan)
	{
	int min, max;

	ad5755_get_min_max(st, chan, &min, &max);
	return (min * (1 << chan->scan_type.realbits)) / (max - min);
	}

	static inline int ad5755_get_scale(struct ad5755_state *st,
	struct iio_chan_spec const *chan)
	{
	int min, max;

	ad5755_get_min_max(st, chan, &min, &max);
	return ((max - min) * 1000000000ULL) >> chan->scan_type.realbits;
	}

	static int ad5755_chan_reg_info(struct ad5755_state *st,
	struct iio_chan_spec const *chan, long info, bool write,
	unsigned int reg, unsigned int shift, unsigned int *offset)
	{
	switch (info) {
	case IIO_CHAN_INFO_RAW:
	if (write)
	*reg = AD5755_WRITE_REG_DATA(chan->address);
	else
	*reg = AD5755_READ_REG_DATA(chan->address);
	*shift = chan->scan_type.shift;
	*offset = 0;
	break;
	case IIO_CHAN_INFO_CALIBBIAS:
	if (write)
	*reg = AD5755_WRITE_REG_OFFSET(chan->address);
	else
	*reg = AD5755_READ_REG_OFFSET(chan->address);
	*shift = st->chip_info->calib_shift;
	*offset = 32768;
	break;
	case IIO_CHAN_INFO_CALIBSCALE:
	if (write)
	*reg = AD5755_WRITE_REG_GAIN(chan->address);
	else
	*reg = AD5755_READ_REG_GAIN(chan->address);
	*shift = st->chip_info->calib_shift;
	*offset = 0;
	break;
	default:
	return -EINVAL;
	}

	return 0;
	}

	static int ad5755_read_raw(struct iio_dev *indio_dev,
	const struct iio_chan_spec chan, int val, int *val2, long info)
	{
	struct ad5755_state *st = iio_priv(indio_dev);
	unsigned int reg, shift, offset;
	int ret;

	switch (info) {
	case IIO_CHAN_INFO_SCALE:
	*val = 0;
	*val2 = ad5755_get_scale(st, chan);
	return IIO_VAL_INT_PLUS_NANO;
	case IIO_CHAN_INFO_OFFSET:
	*val = ad5755_get_offset(st, chan);
	return IIO_VAL_INT;
	default:
	ret = ad5755_chan_reg_info(st, chan, info, false,
	&reg, &shift, &offset);
	if (ret)
	return ret;

	ret = ad5755_read(indio_dev, reg);
	if (ret < 0)
	return ret;

	*val = (ret - offset) >> shift;

	return IIO_VAL_INT;
	}

	return -EINVAL;
	}

	static int ad5755_write_raw(struct iio_dev *indio_dev,
	const struct iio_chan_spec *chan, int val, int val2, long info)
	{
	struct ad5755_state *st = iio_priv(indio_dev);
	unsigned int shift, reg, offset;
	int ret;

	ret = ad5755_chan_reg_info(st, chan, info, true,
	&reg, &shift, &offset);
	if (ret)
	return ret;

	val <<= shift;
	val += offset;

	if (val < 0 \|\| val > 0xffff)
	return -EINVAL;

	return ad5755_write(indio_dev, reg, val);
	}

	static ssize_t ad5755_read_powerdown(struct iio_dev *indio_dev, uintptr_t priv,
	const struct iio_chan_spec chan, char buf)
	{
	struct ad5755_state *st = iio_priv(indio_dev);

	return sprintf(buf, "%d\n",
	(bool)(st->pwr_down & (1 << chan->channel)));
	}

	static ssize_t ad5755_write_powerdown(struct iio_dev *indio_dev, uintptr_t priv,
	struct iio_chan_spec const chan, const char buf, size_t len)
	{
	bool pwr_down;
	int ret;

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

	ret = ad5755_set_channel_pwr_down(indio_dev, chan->channel, pwr_down);
	return ret ? ret : len;
	}

	static const struct iio_info ad5755_info = {
	.read_raw = ad5755_read_raw,
	.write_raw = ad5755_write_raw,
	.driver_module = THIS_MODULE,
	};

	static const struct iio_chan_spec_ext_info ad5755_ext_info[] = {
	{
	.name = "powerdown",
	.read = ad5755_read_powerdown,
	.write = ad5755_write_powerdown,
	},
	{ },
	};

	#define AD5755_CHANNEL(_bits) { \
	.indexed = 1, \
	.output = 1, \
	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT \| \
	IIO_CHAN_INFO_SCALE_SEPARATE_BIT \| \
	IIO_CHAN_INFO_OFFSET_SEPARATE_BIT \| \
	IIO_CHAN_INFO_CALIBSCALE_SEPARATE_BIT \| \
	IIO_CHAN_INFO_CALIBBIAS_SEPARATE_BIT, \
	.scan_type = IIO_ST('u', (_bits), 16, 16 - (_bits)), \
	.ext_info = ad5755_ext_info, \
	}

	static const struct ad5755_chip_info ad5755_chip_info_tbl[] = {
	[ID_AD5735] = {
	.channel_template = AD5755_CHANNEL(14),
	.has_voltage_out = true,
	.calib_shift = 4,
	},
	[ID_AD5737] = {
	.channel_template = AD5755_CHANNEL(14),
	.has_voltage_out = false,
	.calib_shift = 4,
	},
	[ID_AD5755] = {
	.channel_template = AD5755_CHANNEL(16),
	.has_voltage_out = true,
	.calib_shift = 0,
	},
	[ID_AD5757] = {
	.channel_template = AD5755_CHANNEL(16),
	.has_voltage_out = false,
	.calib_shift = 0,
	},
	};

	static bool ad5755_is_valid_mode(struct ad5755_state *st, enum ad5755_mode mode)
	{
	switch (mode) {
	case AD5755_MODE_VOLTAGE_0V_5V:
	case AD5755_MODE_VOLTAGE_0V_10V:
	case AD5755_MODE_VOLTAGE_PLUSMINUS_5V:
	case AD5755_MODE_VOLTAGE_PLUSMINUS_10V:
	return st->chip_info->has_voltage_out;
	case AD5755_MODE_CURRENT_4mA_20mA:
	case AD5755_MODE_CURRENT_0mA_20mA:
	case AD5755_MODE_CURRENT_0mA_24mA:
	return true;
	default:
	return false;
	}
	}

	static int __devinit ad5755_setup_pdata(struct iio_dev *indio_dev,
	const struct ad5755_platform_data *pdata)
	{
	struct ad5755_state *st = iio_priv(indio_dev);
	unsigned int val;
	unsigned int i;
	int ret;

	if (pdata->dc_dc_phase > AD5755_DC_DC_PHASE_90_DEGREE \|\|
	pdata->dc_dc_freq > AD5755_DC_DC_FREQ_650kHZ \|\|
	pdata->dc_dc_maxv > AD5755_DC_DC_MAXV_29V5)
	return -EINVAL;

	val = pdata->dc_dc_maxv << AD5755_DC_DC_MAXV;
	val \|= pdata->dc_dc_freq << AD5755_DC_DC_FREQ_SHIFT;
	val \|= pdata->dc_dc_phase << AD5755_DC_DC_PHASE_SHIFT;
	if (pdata->ext_dc_dc_compenstation_resistor)
	val \|= AD5755_EXT_DC_DC_COMP_RES;

	ret = ad5755_write_ctrl(indio_dev, 0, AD5755_CTRL_REG_DC_DC, val);
	if (ret < 0)
	return ret;

	for (i = 0; i < ARRAY_SIZE(pdata->dac); ++i) {
	val = pdata->dac[i].slew.step_size <<
	AD5755_SLEW_STEP_SIZE_SHIFT;
	val \|= pdata->dac[i].slew.rate <<
	AD5755_SLEW_RATE_SHIFT;
	if (pdata->dac[i].slew.enable)
	val \|= AD5755_SLEW_ENABLE;

	ret = ad5755_write_ctrl(indio_dev, i,
	AD5755_CTRL_REG_SLEW, val);
	if (ret < 0)
	return ret;
	}

	for (i = 0; i < ARRAY_SIZE(pdata->dac); ++i) {
	if (!ad5755_is_valid_mode(st, pdata->dac[i].mode))
	return -EINVAL;

	val = 0;
	if (!pdata->dac[i].ext_current_sense_resistor)
	val \|= AD5755_DAC_INT_CURRENT_SENSE_RESISTOR;
	if (pdata->dac[i].enable_voltage_overrange)
	val \|= AD5755_DAC_VOLTAGE_OVERRANGE_EN;
	val \|= pdata->dac[i].mode;

	ret = ad5755_update_dac_ctrl(indio_dev, i, val, 0);
	if (ret < 0)
	return ret;
	}

	return 0;
	}

	static bool __devinit ad5755_is_voltage_mode(enum ad5755_mode mode)
	{
	switch (mode) {
	case AD5755_MODE_VOLTAGE_0V_5V:
	case AD5755_MODE_VOLTAGE_0V_10V:
	case AD5755_MODE_VOLTAGE_PLUSMINUS_5V:
	case AD5755_MODE_VOLTAGE_PLUSMINUS_10V:
	return true;
	default:
	return false;
	}
	}

	static int __devinit ad5755_init_channels(struct iio_dev *indio_dev,
	const struct ad5755_platform_data *pdata)
	{
	struct ad5755_state *st = iio_priv(indio_dev);
	struct iio_chan_spec *channels = st->channels;
	unsigned int i;

	for (i = 0; i < AD5755_NUM_CHANNELS; ++i) {
	channels[i] = st->chip_info->channel_template;
	channels[i].channel = i;
	channels[i].address = i;
	if (pdata && ad5755_is_voltage_mode(pdata->dac[i].mode))
	channels[i].type = IIO_VOLTAGE;
	else
	channels[i].type = IIO_CURRENT;
	}

	indio_dev->channels = channels;

	return 0;
	}

	#define AD5755_DEFAULT_DAC_PDATA { \
	.mode = AD5755_MODE_CURRENT_4mA_20mA, \
	.ext_current_sense_resistor = true, \
	.enable_voltage_overrange = false, \
	.slew = { \
	.enable = false, \
	.rate = AD5755_SLEW_RATE_64k, \
	.step_size = AD5755_SLEW_STEP_SIZE_1, \
	}, \
	}

	static const struct ad5755_platform_data ad5755_default_pdata = {
	.ext_dc_dc_compenstation_resistor = false,
	.dc_dc_phase = AD5755_DC_DC_PHASE_ALL_SAME_EDGE,
	.dc_dc_freq = AD5755_DC_DC_FREQ_410kHZ,
	.dc_dc_maxv = AD5755_DC_DC_MAXV_23V,
	.dac = {
	[0] = AD5755_DEFAULT_DAC_PDATA,
	[1] = AD5755_DEFAULT_DAC_PDATA,
	[2] = AD5755_DEFAULT_DAC_PDATA,
	[3] = AD5755_DEFAULT_DAC_PDATA,
	},
	};

	static int __devinit ad5755_probe(struct spi_device *spi)
	{
	enum ad5755_type type = spi_get_device_id(spi)->driver_data;
	const struct ad5755_platform_data *pdata = dev_get_platdata(&spi->dev);
	struct iio_dev *indio_dev;
	struct ad5755_state *st;
	int ret;

	indio_dev = iio_device_alloc(sizeof(*st));
	if (indio_dev == NULL) {
	dev_err(&spi->dev, "Failed to allocate iio device\n");
	return -ENOMEM;
	}

	st = iio_priv(indio_dev);
	spi_set_drvdata(spi, indio_dev);

	st->chip_info = &ad5755_chip_info_tbl[type];
	st->spi = spi;
	st->pwr_down = 0xf;

	indio_dev->dev.parent = &spi->dev;
	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->info = &ad5755_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->num_channels = AD5755_NUM_CHANNELS;

	if (!pdata)
	pdata = &ad5755_default_pdata;

	ret = ad5755_init_channels(indio_dev, pdata);
	if (ret)
	goto error_free;

	ret = ad5755_setup_pdata(indio_dev, pdata);
	if (ret)
	goto error_free;

	ret = iio_device_register(indio_dev);
	if (ret) {
	dev_err(&spi->dev, "Failed to register iio device: %d\n", ret);
	goto error_free;
	}

	return 0;

	error_free:
	iio_device_free(indio_dev);

	return ret;
	}

	static int __devexit ad5755_remove(struct spi_device *spi)
	{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);

	iio_device_unregister(indio_dev);
	iio_device_free(indio_dev);

	return 0;
	}

	static const struct spi_device_id ad5755_id[] = {
	{ "ad5755", ID_AD5755 },
	{ "ad5755-1", ID_AD5755 },
	{ "ad5757", ID_AD5757 },
	{ "ad5735", ID_AD5735 },
	{ "ad5737", ID_AD5737 },
	{}
	};
	MODULE_DEVICE_TABLE(spi, ad5755_id);

	static struct spi_driver ad5755_driver = {
	.driver = {
	.name = "ad5755",
	.owner = THIS_MODULE,
	},
	.probe = ad5755_probe,
	.remove = __devexit_p(ad5755_remove),
	.id_table = ad5755_id,
	};
	module_spi_driver(ad5755_driver);

	MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
	MODULE_DESCRIPTION("Analog Devices AD5755/55-1/57/35/37 DAC");
	MODULE_LICENSE("GPL v2");