iio:dac: Add ad5755 driver

This patch adds support for the AD5755, AD5755-1, AD5757, AD5735, AD5737 16 and
14 bit quad-channel DACs. The AD5757/AD5737 only have current outputs, but
for the AD5755/AD5757 each of the outputs can be configured to either be a
voltage or a current output. We only allow to configure this at device probe
time since usually this needs to match the external circuitry and should not be
changed on the fly.

A few trivial formatting changes on merge.

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/dac/Kconfig

···
 	  To compile this driver as a module, choose M here: the
 	  module will be called ad5504.
 
+config AD5755
+	tristate "Analog Devices AD5755/AD5755-1/AD5757/AD5735/AD5737 DAC driver"
+	depends on SPI_MASTER
+	help
+	  Say yes here to build support for Analog Devices AD5755, AD5755-1,
+	  AD5757, AD5735, AD5737 quad channel Digital to
+	  Analog Converter.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad5755.
+
 config AD5764
 	tristate "Analog Devices AD5764/64R/44/44R DAC driver"
 	depends on SPI_MASTER

drivers/iio/dac/Makefile

···
 obj-$(CONFIG_AD5064) += ad5064.o
 obj-$(CONFIG_AD5504) += ad5504.o
 obj-$(CONFIG_AD5446) += ad5446.o
+obj-$(CONFIG_AD5755) += ad5755.o
 obj-$(CONFIG_AD5764) += ad5764.o
 obj-$(CONFIG_AD5791) += ad5791.o
 obj-$(CONFIG_AD5686) += ad5686.o

drivers/iio/dac/ad5755.c

···
+/*
+ * 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 ret;
+	unsigned int val;
+	unsigned int i;
+
+	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 <[e-mail]>");
+MODULE_DESCRIPTION("Analog Devices AD5755/55-1/57/35/37 DAC");
+MODULE_LICENSE("GPL v2");

include/linux/platform_data/ad5755.h

···
+/*
+ * Copyright 2012 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+#ifndef __LINUX_PLATFORM_DATA_AD5755_H__
+#define __LINUX_PLATFORM_DATA_AD5755_H__
+
+enum ad5755_mode {
+	AD5755_MODE_VOLTAGE_0V_5V		= 0,
+	AD5755_MODE_VOLTAGE_0V_10V		= 1,
+	AD5755_MODE_VOLTAGE_PLUSMINUS_5V	= 2,
+	AD5755_MODE_VOLTAGE_PLUSMINUS_10V	= 3,
+	AD5755_MODE_CURRENT_4mA_20mA		= 4,
+	AD5755_MODE_CURRENT_0mA_20mA		= 5,
+	AD5755_MODE_CURRENT_0mA_24mA		= 6,
+};
+
+enum ad5755_dc_dc_phase {
+	AD5755_DC_DC_PHASE_ALL_SAME_EDGE		= 0,
+	AD5755_DC_DC_PHASE_A_B_SAME_EDGE_C_D_OPP_EDGE	= 1,
+	AD5755_DC_DC_PHASE_A_C_SAME_EDGE_B_D_OPP_EDGE	= 2,
+	AD5755_DC_DC_PHASE_90_DEGREE			= 3,
+};
+
+enum ad5755_dc_dc_freq {
+	AD5755_DC_DC_FREQ_250kHZ = 0,
+	AD5755_DC_DC_FREQ_410kHZ = 1,
+	AD5755_DC_DC_FREQ_650kHZ = 2,
+};
+
+enum ad5755_dc_dc_maxv {
+	AD5755_DC_DC_MAXV_23V	= 0,
+	AD5755_DC_DC_MAXV_24V5	= 1,
+	AD5755_DC_DC_MAXV_27V	= 2,
+	AD5755_DC_DC_MAXV_29V5	= 3,
+};
+
+enum ad5755_slew_rate {
+	AD5755_SLEW_RATE_64k	= 0,
+	AD5755_SLEW_RATE_32k	= 1,
+	AD5755_SLEW_RATE_16k	= 2,
+	AD5755_SLEW_RATE_8k	= 3,
+	AD5755_SLEW_RATE_4k	= 4,
+	AD5755_SLEW_RATE_2k	= 5,
+	AD5755_SLEW_RATE_1k	= 6,
+	AD5755_SLEW_RATE_500	= 7,
+	AD5755_SLEW_RATE_250	= 8,
+	AD5755_SLEW_RATE_125	= 9,
+	AD5755_SLEW_RATE_64	= 10,
+	AD5755_SLEW_RATE_32	= 11,
+	AD5755_SLEW_RATE_16	= 12,
+	AD5755_SLEW_RATE_8	= 13,
+	AD5755_SLEW_RATE_4	= 14,
+	AD5755_SLEW_RATE_0_5	= 15,
+};
+
+enum ad5755_slew_step_size {
+	AD5755_SLEW_STEP_SIZE_1 = 0,
+	AD5755_SLEW_STEP_SIZE_2 = 1,
+	AD5755_SLEW_STEP_SIZE_4 = 2,
+	AD5755_SLEW_STEP_SIZE_8 = 3,
+	AD5755_SLEW_STEP_SIZE_16 = 4,
+	AD5755_SLEW_STEP_SIZE_32 = 5,
+	AD5755_SLEW_STEP_SIZE_64 = 6,
+	AD5755_SLEW_STEP_SIZE_128 = 7,
+	AD5755_SLEW_STEP_SIZE_256 = 8,
+};
+
+/**
+ * struct ad5755_platform_data - AD5755 DAC driver platform data
+ * @ext_dc_dc_compenstation_resistor: Whether an external DC-DC converter
+ * compensation register is used.
+ * @dc_dc_phase: DC-DC converter phase.
+ * @dc_dc_freq: DC-DC converter frequency.
+ * @dc_dc_maxv: DC-DC maximum allowed boost voltage.
+ * @dac.mode: The mode to be used for the DAC output.
+ * @dac.ext_current_sense_resistor: Whether an external current sense resistor
+ * is used.
+ * @dac.enable_voltage_overrange: Whether to enable 20% voltage output overrange.
+ * @dac.slew.enable: Whether to enable digital slew.
+ * @dac.slew.rate: Slew rate of the digital slew.
+ * @dac.slew.step_size: Slew step size of the digital slew.
+ **/
+struct ad5755_platform_data {
+	bool ext_dc_dc_compenstation_resistor;
+	enum ad5755_dc_dc_phase dc_dc_phase;
+	enum ad5755_dc_dc_freq dc_dc_freq;
+	enum ad5755_dc_dc_maxv dc_dc_maxv;
+
+	struct {
+		enum ad5755_mode mode;
+		bool ext_current_sense_resistor;
+		bool enable_voltage_overrange;
+		struct {
+			bool enable;
+			enum ad5755_slew_rate rate;
+			enum ad5755_slew_step_size step_size;
+		} slew;
+	} dac[4];
+};
+
+#endif