drivers/iio/adc/ad7298.c - kernel/msm-4.9 - Gitiles

 /*
  * AD7298 SPI ADC driver
  *
  * Copyright 2011 Analog Devices Inc.
  *
  * Licensed under the GPL-2.
  */

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

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

 #include <linux/platform_data/ad7298.h>

 #define AD7298_WRITE	(1 << 15) /* write to the control register */
 #define AD7298_REPEAT	(1 << 14) /* repeated conversion enable */
 #define AD7298_CH(x)	(1 << (13 - (x))) /* channel select */
 #define AD7298_TSENSE	(1 << 5) /* temperature conversion enable */
 #define AD7298_EXTREF	(1 << 2) /* external reference enable */
 #define AD7298_TAVG	(1 << 1) /* temperature sensor averaging enable */
 #define AD7298_PDD	(1 << 0) /* partial power down enable */

 #define AD7298_MAX_CHAN		8
 #define AD7298_BITS		12
 #define AD7298_STORAGE_BITS	16
 #define AD7298_INTREF_mV	2500

 #define AD7298_CH_TEMP		9

 #define RES_MASK(bits)	((1 << (bits)) - 1)

 struct ad7298_state {
 	struct spi_device		*spi;
 	struct regulator		*reg;
 	unsigned			ext_ref;
 	struct spi_transfer		ring_xfer[10];
 	struct spi_transfer		scan_single_xfer[3];
 	struct spi_message		ring_msg;
 	struct spi_message		scan_single_msg;
 	/*
 	 * DMA (thus cache coherency maintenance) requires the
 	 * transfer buffers to live in their own cache lines.
 	 */
 	__be16				rx_buf[12] ____cacheline_aligned;
 	__be16				tx_buf[2];
 };

 #define AD7298_V_CHAN(index)						\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.indexed = 1,						\
 		.channel = index,					\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
 		.address = index,					\
 		.scan_index = index,					\
 		.scan_type = {						\
 			.sign = 'u',					\
 			.realbits = 12,					\
 			.storagebits = 16,				\
 			.endianness = IIO_BE,				\
 		},							\
 	}

 static const struct iio_chan_spec ad7298_channels[] = {
 	{
 		.type = IIO_TEMP,
 		.indexed = 1,
 		.channel = 0,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 			BIT(IIO_CHAN_INFO_SCALE) |
 			BIT(IIO_CHAN_INFO_OFFSET),
 		.address = AD7298_CH_TEMP,
 		.scan_index = -1,
 		.scan_type = {
 			.sign = 's',
 			.realbits = 32,
 			.storagebits = 32,
 		},
 	},
 	AD7298_V_CHAN(0),
 	AD7298_V_CHAN(1),
 	AD7298_V_CHAN(2),
 	AD7298_V_CHAN(3),
 	AD7298_V_CHAN(4),
 	AD7298_V_CHAN(5),
 	AD7298_V_CHAN(6),
 	AD7298_V_CHAN(7),
 	IIO_CHAN_SOFT_TIMESTAMP(8),
 };

 /**
  * ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
  **/
 static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
 	const unsigned long *active_scan_mask)
 {
 	struct ad7298_state *st = iio_priv(indio_dev);
 	int i, m;
 	unsigned short command;
 	int scan_count;

 	/* Now compute overall size */
 	scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength);

 	command = AD7298_WRITE | st->ext_ref;

 	for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
 		if (test_bit(i, active_scan_mask))
 			command |= m;

 	st->tx_buf[0] = cpu_to_be16(command);

 	/* build spi ring message */
 	st->ring_xfer[0].tx_buf = &st->tx_buf[0];
 	st->ring_xfer[0].len = 2;
 	st->ring_xfer[0].cs_change = 1;
 	st->ring_xfer[1].tx_buf = &st->tx_buf[1];
 	st->ring_xfer[1].len = 2;
 	st->ring_xfer[1].cs_change = 1;

 	spi_message_init(&st->ring_msg);
 	spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
 	spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);

 	for (i = 0; i < scan_count; i++) {
 		st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
 		st->ring_xfer[i + 2].len = 2;
 		st->ring_xfer[i + 2].cs_change = 1;
 		spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
 	}
 	/* make sure last transfer cs_change is not set */
 	st->ring_xfer[i + 1].cs_change = 0;

 	return 0;
 }

 /**
  * ad7298_trigger_handler() bh of trigger launched polling to ring buffer
  *
  * Currently there is no option in this driver to disable the saving of
  * timestamps within the ring.
  **/
 static irqreturn_t ad7298_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct ad7298_state *st = iio_priv(indio_dev);
 	s64 time_ns = 0;
 	int b_sent;

 	b_sent = spi_sync(st->spi, &st->ring_msg);
 	if (b_sent)
 		goto done;

 	if (indio_dev->scan_timestamp) {
 		time_ns = iio_get_time_ns();
 		memcpy((u8 *)st->rx_buf + indio_dev->scan_bytes - sizeof(s64),
 			&time_ns, sizeof(time_ns));
 	}

 	iio_push_to_buffers(indio_dev, (u8 *)st->rx_buf);

 done:
 	iio_trigger_notify_done(indio_dev->trig);

 	return IRQ_HANDLED;
 }

 static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
 {
 	int ret;
 	st->tx_buf[0] = cpu_to_be16(AD7298_WRITE | st->ext_ref |
 				   (AD7298_CH(0) >> ch));

 	ret = spi_sync(st->spi, &st->scan_single_msg);
 	if (ret)
 		return ret;

 	return be16_to_cpu(st->rx_buf[0]);
 }

 static int ad7298_scan_temp(struct ad7298_state *st, int *val)
 {
 	int ret;
 	__be16 buf;

 	buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
 			  AD7298_TAVG | st->ext_ref);

 	ret = spi_write(st->spi, (u8 *)&buf, 2);
 	if (ret)
 		return ret;

 	buf = cpu_to_be16(0);

 	ret = spi_write(st->spi, (u8 *)&buf, 2);
 	if (ret)
 		return ret;

 	usleep_range(101, 1000); /* sleep > 100us */

 	ret = spi_read(st->spi, (u8 *)&buf, 2);
 	if (ret)
 		return ret;

 	*val = sign_extend32(be16_to_cpu(buf), 11);

 	return 0;
 }

 static int ad7298_get_ref_voltage(struct ad7298_state *st)
 {
 	int vref;

 	if (st->ext_ref) {
 		vref = regulator_get_voltage(st->reg);
 		if (vref < 0)
 			return vref;

 		return vref / 1000;
 	} else {
 		return AD7298_INTREF_mV;
 	}
 }

 static int ad7298_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val,
 			   int *val2,
 			   long m)
 {
 	int ret;
 	struct ad7298_state *st = iio_priv(indio_dev);

 	switch (m) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&indio_dev->mlock);
 		if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
 			ret = -EBUSY;
 		} else {
 			if (chan->address == AD7298_CH_TEMP)
 				ret = ad7298_scan_temp(st, val);
 			else
 				ret = ad7298_scan_direct(st, chan->address);
 		}
 		mutex_unlock(&indio_dev->mlock);

 		if (ret < 0)
 			return ret;

 		if (chan->address != AD7298_CH_TEMP)
 			*val = ret & RES_MASK(AD7298_BITS);

 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_VOLTAGE:
 			*val = ad7298_get_ref_voltage(st);
 			*val2 = chan->scan_type.realbits;
 			return IIO_VAL_FRACTIONAL_LOG2;
 		case IIO_TEMP:
 			*val = ad7298_get_ref_voltage(st);
 			*val2 = 10;
 			return IIO_VAL_FRACTIONAL;
 		default:
 			return -EINVAL;
 		}
 	case IIO_CHAN_INFO_OFFSET:
 		*val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
 		return IIO_VAL_INT;
 	}
 	return -EINVAL;
 }

 static const struct iio_info ad7298_info = {
 	.read_raw = &ad7298_read_raw,
 	.update_scan_mode = ad7298_update_scan_mode,
 	.driver_module = THIS_MODULE,
 };

 static int ad7298_probe(struct spi_device *spi)
 {
 	struct ad7298_platform_data *pdata = spi->dev.platform_data;
 	struct ad7298_state *st;
 	struct iio_dev *indio_dev;
 	int ret;

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

 	st = iio_priv(indio_dev);

 	if (pdata && pdata->ext_ref)
 		st->ext_ref = AD7298_EXTREF;

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

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

 	spi_set_drvdata(spi, indio_dev);

 	st->spi = spi;

 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->dev.parent = &spi->dev;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = ad7298_channels;
 	indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
 	indio_dev->info = &ad7298_info;

 	/* Setup default message */

 	st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
 	st->scan_single_xfer[0].len = 2;
 	st->scan_single_xfer[0].cs_change = 1;
 	st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
 	st->scan_single_xfer[1].len = 2;
 	st->scan_single_xfer[1].cs_change = 1;
 	st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
 	st->scan_single_xfer[2].len = 2;

 	spi_message_init(&st->scan_single_msg);
 	spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
 	spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
 	spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);

 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 			&ad7298_trigger_handler, NULL);
 	if (ret)
 		goto error_disable_reg;

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

 	return 0;

 error_cleanup_ring:
 	iio_triggered_buffer_cleanup(indio_dev);
 error_disable_reg:
 	if (st->ext_ref)
 		regulator_disable(st->reg);

 	return ret;
 }

 static int ad7298_remove(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
 	struct ad7298_state *st = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);
 	iio_triggered_buffer_cleanup(indio_dev);
 	if (st->ext_ref)
 		regulator_disable(st->reg);

 	return 0;
 }

 static const struct spi_device_id ad7298_id[] = {
 	{"ad7298", 0},
 	{}
 };
 MODULE_DEVICE_TABLE(spi, ad7298_id);

 static struct spi_driver ad7298_driver = {
 	.driver = {
 		.name	= "ad7298",
 		.owner	= THIS_MODULE,
 	},
 	.probe		= ad7298_probe,
 	.remove		= ad7298_remove,
 	.id_table	= ad7298_id,
 };
 module_spi_driver(ad7298_driver);

 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
 MODULE_LICENSE("GPL v2");
	/*
	* AD7298 SPI ADC driver
	*
	* Copyright 2011 Analog Devices Inc.
	*
	* Licensed under the GPL-2.
	*/

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

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

	#include <linux/platform_data/ad7298.h>

	#define AD7298_WRITE (1 << 15) /* write to the control register */
	#define AD7298_REPEAT (1 << 14) /* repeated conversion enable */
	#define AD7298_CH(x) (1 << (13 - (x))) /* channel select */
	#define AD7298_TSENSE (1 << 5) /* temperature conversion enable */
	#define AD7298_EXTREF (1 << 2) /* external reference enable */
	#define AD7298_TAVG (1 << 1) /* temperature sensor averaging enable */
	#define AD7298_PDD (1 << 0) /* partial power down enable */

	#define AD7298_MAX_CHAN 8
	#define AD7298_BITS 12
	#define AD7298_STORAGE_BITS 16
	#define AD7298_INTREF_mV 2500

	#define AD7298_CH_TEMP 9

	#define RES_MASK(bits) ((1 << (bits)) - 1)

	struct ad7298_state {
	struct spi_device *spi;
	struct regulator *reg;
	unsigned ext_ref;
	struct spi_transfer ring_xfer[10];
	struct spi_transfer scan_single_xfer[3];
	struct spi_message ring_msg;
	struct spi_message scan_single_msg;
	/*
	* DMA (thus cache coherency maintenance) requires the
	* transfer buffers to live in their own cache lines.
	*/
	__be16 rx_buf[12] ____cacheline_aligned;
	__be16 tx_buf[2];
	};

	#define AD7298_V_CHAN(index) \
	{ \
	.type = IIO_VOLTAGE, \
	.indexed = 1, \
	.channel = index, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
	.address = index, \
	.scan_index = index, \
	.scan_type = { \
	.sign = 'u', \
	.realbits = 12, \
	.storagebits = 16, \
	.endianness = IIO_BE, \
	}, \
	}

	static const struct iio_chan_spec ad7298_channels[] = {
	{
	.type = IIO_TEMP,
	.indexed = 1,
	.channel = 0,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
	BIT(IIO_CHAN_INFO_SCALE) \|
	BIT(IIO_CHAN_INFO_OFFSET),
	.address = AD7298_CH_TEMP,
	.scan_index = -1,
	.scan_type = {
	.sign = 's',
	.realbits = 32,
	.storagebits = 32,
	},
	},
	AD7298_V_CHAN(0),
	AD7298_V_CHAN(1),
	AD7298_V_CHAN(2),
	AD7298_V_CHAN(3),
	AD7298_V_CHAN(4),
	AD7298_V_CHAN(5),
	AD7298_V_CHAN(6),
	AD7298_V_CHAN(7),
	IIO_CHAN_SOFT_TIMESTAMP(8),
	};

	/**
	* ad7298_update_scan_mode() setup the spi transfer buffer for the new scan mask
	**/
	static int ad7298_update_scan_mode(struct iio_dev *indio_dev,
	const unsigned long *active_scan_mask)
	{
	struct ad7298_state *st = iio_priv(indio_dev);
	int i, m;
	unsigned short command;
	int scan_count;

	/* Now compute overall size */
	scan_count = bitmap_weight(active_scan_mask, indio_dev->masklength);

	command = AD7298_WRITE \| st->ext_ref;

	for (i = 0, m = AD7298_CH(0); i < AD7298_MAX_CHAN; i++, m >>= 1)
	if (test_bit(i, active_scan_mask))
	command \|= m;

	st->tx_buf[0] = cpu_to_be16(command);

	/* build spi ring message */
	st->ring_xfer[0].tx_buf = &st->tx_buf[0];
	st->ring_xfer[0].len = 2;
	st->ring_xfer[0].cs_change = 1;
	st->ring_xfer[1].tx_buf = &st->tx_buf[1];
	st->ring_xfer[1].len = 2;
	st->ring_xfer[1].cs_change = 1;

	spi_message_init(&st->ring_msg);
	spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
	spi_message_add_tail(&st->ring_xfer[1], &st->ring_msg);

	for (i = 0; i < scan_count; i++) {
	st->ring_xfer[i + 2].rx_buf = &st->rx_buf[i];
	st->ring_xfer[i + 2].len = 2;
	st->ring_xfer[i + 2].cs_change = 1;
	spi_message_add_tail(&st->ring_xfer[i + 2], &st->ring_msg);
	}
	/* make sure last transfer cs_change is not set */
	st->ring_xfer[i + 1].cs_change = 0;

	return 0;
	}

	/**
	* ad7298_trigger_handler() bh of trigger launched polling to ring buffer
	*
	* Currently there is no option in this driver to disable the saving of
	* timestamps within the ring.
	**/
	static irqreturn_t ad7298_trigger_handler(int irq, void *p)
	{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct ad7298_state *st = iio_priv(indio_dev);
	s64 time_ns = 0;
	int b_sent;

	b_sent = spi_sync(st->spi, &st->ring_msg);
	if (b_sent)
	goto done;

	if (indio_dev->scan_timestamp) {
	time_ns = iio_get_time_ns();
	memcpy((u8 *)st->rx_buf + indio_dev->scan_bytes - sizeof(s64),
	&time_ns, sizeof(time_ns));
	}

	iio_push_to_buffers(indio_dev, (u8 *)st->rx_buf);

	done:
	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
	}

	static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
	{
	int ret;
	st->tx_buf[0] = cpu_to_be16(AD7298_WRITE \| st->ext_ref \|
	(AD7298_CH(0) >> ch));

	ret = spi_sync(st->spi, &st->scan_single_msg);
	if (ret)
	return ret;

	return be16_to_cpu(st->rx_buf[0]);
	}

	static int ad7298_scan_temp(struct ad7298_state st, int val)
	{
	int ret;
	__be16 buf;

	buf = cpu_to_be16(AD7298_WRITE \| AD7298_TSENSE \|
	AD7298_TAVG \| st->ext_ref);

	ret = spi_write(st->spi, (u8 *)&buf, 2);
	if (ret)
	return ret;

	buf = cpu_to_be16(0);

	ret = spi_write(st->spi, (u8 *)&buf, 2);
	if (ret)
	return ret;

	usleep_range(101, 1000); /* sleep > 100us */

	ret = spi_read(st->spi, (u8 *)&buf, 2);
	if (ret)
	return ret;

	*val = sign_extend32(be16_to_cpu(buf), 11);

	return 0;
	}

	static int ad7298_get_ref_voltage(struct ad7298_state *st)
	{
	int vref;

	if (st->ext_ref) {
	vref = regulator_get_voltage(st->reg);
	if (vref < 0)
	return vref;

	return vref / 1000;
	} else {
	return AD7298_INTREF_mV;
	}
	}

	static int ad7298_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int *val,
	int *val2,
	long m)
	{
	int ret;
	struct ad7298_state *st = iio_priv(indio_dev);

	switch (m) {
	case IIO_CHAN_INFO_RAW:
	mutex_lock(&indio_dev->mlock);
	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
	ret = -EBUSY;
	} else {
	if (chan->address == AD7298_CH_TEMP)
	ret = ad7298_scan_temp(st, val);
	else
	ret = ad7298_scan_direct(st, chan->address);
	}
	mutex_unlock(&indio_dev->mlock);

	if (ret < 0)
	return ret;

	if (chan->address != AD7298_CH_TEMP)
	*val = ret & RES_MASK(AD7298_BITS);

	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	switch (chan->type) {
	case IIO_VOLTAGE:
	*val = ad7298_get_ref_voltage(st);
	*val2 = chan->scan_type.realbits;
	return IIO_VAL_FRACTIONAL_LOG2;
	case IIO_TEMP:
	*val = ad7298_get_ref_voltage(st);
	*val2 = 10;
	return IIO_VAL_FRACTIONAL;
	default:
	return -EINVAL;
	}
	case IIO_CHAN_INFO_OFFSET:
	*val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
	return IIO_VAL_INT;
	}
	return -EINVAL;
	}

	static const struct iio_info ad7298_info = {
	.read_raw = &ad7298_read_raw,
	.update_scan_mode = ad7298_update_scan_mode,
	.driver_module = THIS_MODULE,
	};

	static int ad7298_probe(struct spi_device *spi)
	{
	struct ad7298_platform_data *pdata = spi->dev.platform_data;
	struct ad7298_state *st;
	struct iio_dev *indio_dev;
	int ret;

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

	st = iio_priv(indio_dev);

	if (pdata && pdata->ext_ref)
	st->ext_ref = AD7298_EXTREF;

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

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

	spi_set_drvdata(spi, indio_dev);

	st->spi = spi;

	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->dev.parent = &spi->dev;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = ad7298_channels;
	indio_dev->num_channels = ARRAY_SIZE(ad7298_channels);
	indio_dev->info = &ad7298_info;

	/* Setup default message */

	st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
	st->scan_single_xfer[0].len = 2;
	st->scan_single_xfer[0].cs_change = 1;
	st->scan_single_xfer[1].tx_buf = &st->tx_buf[1];
	st->scan_single_xfer[1].len = 2;
	st->scan_single_xfer[1].cs_change = 1;
	st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
	st->scan_single_xfer[2].len = 2;

	spi_message_init(&st->scan_single_msg);
	spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
	spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
	spi_message_add_tail(&st->scan_single_xfer[2], &st->scan_single_msg);

	ret = iio_triggered_buffer_setup(indio_dev, NULL,
	&ad7298_trigger_handler, NULL);
	if (ret)
	goto error_disable_reg;

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

	return 0;

	error_cleanup_ring:
	iio_triggered_buffer_cleanup(indio_dev);
	error_disable_reg:
	if (st->ext_ref)
	regulator_disable(st->reg);

	return ret;
	}

	static int ad7298_remove(struct spi_device *spi)
	{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct ad7298_state *st = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	iio_triggered_buffer_cleanup(indio_dev);
	if (st->ext_ref)
	regulator_disable(st->reg);

	return 0;
	}

	static const struct spi_device_id ad7298_id[] = {
	{"ad7298", 0},
	{}
	};
	MODULE_DEVICE_TABLE(spi, ad7298_id);

	static struct spi_driver ad7298_driver = {
	.driver = {
	.name = "ad7298",
	.owner = THIS_MODULE,
	},
	.probe = ad7298_probe,
	.remove = ad7298_remove,
	.id_table = ad7298_id,
	};
	module_spi_driver(ad7298_driver);

	MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
	MODULE_DESCRIPTION("Analog Devices AD7298 ADC");
	MODULE_LICENSE("GPL v2");