drivers/iio/magnetometer/mag3110.c - arm/linux-arm-legacy - Git at Google

 /*
  * mag3110.c - Support for Freescale MAG3110 magnetometer sensor
  *
  * Copyright (c) 2013 Peter Meerwald <pmeerw@pmeerw.net>
  *
  * This file is subject to the terms and conditions of version 2 of
  * the GNU General Public License.  See the file COPYING in the main
  * directory of this archive for more details.
  *
  * (7-bit I2C slave address 0x0e)
  *
  * TODO: irq, user offset, oversampling, continuous mode
  */

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/delay.h>

 #define MAG3110_STATUS 0x00
 #define MAG3110_OUT_X 0x01 /* MSB first */
 #define MAG3110_OUT_Y 0x03
 #define MAG3110_OUT_Z 0x05
 #define MAG3110_WHO_AM_I 0x07
 #define MAG3110_OFF_X 0x09 /* MSB first */
 #define MAG3110_OFF_Y 0x0b
 #define MAG3110_OFF_Z 0x0d
 #define MAG3110_DIE_TEMP 0x0f
 #define MAG3110_CTRL_REG1 0x10
 #define MAG3110_CTRL_REG2 0x11

 #define MAG3110_STATUS_DRDY (BIT(2) | BIT(1) | BIT(0))

 #define MAG3110_CTRL_DR_MASK (BIT(7) | BIT(6) | BIT(5))
 #define MAG3110_CTRL_DR_SHIFT 5
 #define MAG3110_CTRL_DR_DEFAULT 0

 #define MAG3110_CTRL_TM BIT(1) /* trigger single measurement */
 #define MAG3110_CTRL_AC BIT(0) /* continuous measurements */

 #define MAG3110_CTRL_AUTO_MRST_EN BIT(7) /* magnetic auto-reset */
 #define MAG3110_CTRL_RAW BIT(5) /* measurements not user-offset corrected */

 #define MAG3110_DEVICE_ID 0xc4

 /* Each client has this additional data */
 struct mag3110_data {
 	struct i2c_client *client;
 	struct mutex lock;
 	u8 ctrl_reg1;
 };

 static int mag3110_request(struct mag3110_data *data)
 {
 	int ret, tries = 150;

 	/* trigger measurement */
 	ret = i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
 		data->ctrl_reg1 | MAG3110_CTRL_TM);
 	if (ret < 0)
 		return ret;

 	while (tries-- > 0) {
 		ret = i2c_smbus_read_byte_data(data->client, MAG3110_STATUS);
 		if (ret < 0)
 			return ret;
 		/* wait for data ready */
 		if ((ret & MAG3110_STATUS_DRDY) == MAG3110_STATUS_DRDY)
 			break;
 		msleep(20);
 	}

 	if (tries < 0) {
 		dev_err(&data->client->dev, "data not ready\n");
 		return -EIO;
 	}

 	return 0;
 }

 static int mag3110_read(struct mag3110_data *data, __be16 buf[3])
 {
 	int ret;

 	mutex_lock(&data->lock);
 	ret = mag3110_request(data);
 	if (ret < 0) {
 		mutex_unlock(&data->lock);
 		return ret;
 	}
 	ret = i2c_smbus_read_i2c_block_data(data->client,
 		MAG3110_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
 	mutex_unlock(&data->lock);

 	return ret;
 }

 static ssize_t mag3110_show_int_plus_micros(char *buf,
 	const int (*vals)[2], int n)
 {
 	size_t len = 0;

 	while (n-- > 0)
 		len += scnprintf(buf + len, PAGE_SIZE - len,
 			"%d.%06d ", vals[n][0], vals[n][1]);

 	/* replace trailing space by newline */
 	buf[len - 1] = '\n';

 	return len;
 }

 static int mag3110_get_int_plus_micros_index(const int (*vals)[2], int n,
 					int val, int val2)
 {
 	while (n-- > 0)
 		if (val == vals[n][0] && val2 == vals[n][1])
 			return n;

 	return -EINVAL;
 }

 static const int mag3110_samp_freq[8][2] = {
 	{80, 0}, {40, 0}, {20, 0}, {10, 0}, {5, 0}, {2, 500000},
 	{1, 250000}, {0, 625000}
 };

 static ssize_t mag3110_show_samp_freq_avail(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	return mag3110_show_int_plus_micros(buf, mag3110_samp_freq, 8);
 }

 static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mag3110_show_samp_freq_avail);

 static int mag3110_get_samp_freq_index(struct mag3110_data *data,
 	int val, int val2)
 {
 	return mag3110_get_int_plus_micros_index(mag3110_samp_freq, 8, val,
 		val2);
 }

 static int mag3110_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int *val, int *val2, long mask)
 {
 	struct mag3110_data *data = iio_priv(indio_dev);
 	__be16 buffer[3];
 	int i, ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		if (iio_buffer_enabled(indio_dev))
 			return -EBUSY;

 		switch (chan->type) {
 		case IIO_MAGN: /* in 0.1 uT / LSB */
 			ret = mag3110_read(data, buffer);
 			if (ret < 0)
 				return ret;
 			*val = sign_extend32(
 				be16_to_cpu(buffer[chan->scan_index]), 15);
 			return IIO_VAL_INT;
 		case IIO_TEMP: /* in 1 C / LSB */
 			mutex_lock(&data->lock);
 			ret = mag3110_request(data);
 			if (ret < 0) {
 				mutex_unlock(&data->lock);
 				return ret;
 			}
 			ret = i2c_smbus_read_byte_data(data->client,
 				MAG3110_DIE_TEMP);
 			mutex_unlock(&data->lock);
 			if (ret < 0)
 				return ret;
 			*val = sign_extend32(ret, 7);
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;
 		}
 	case IIO_CHAN_INFO_SCALE:
 		*val = 0;
 		*val2 = 1000;
 		return IIO_VAL_INT_PLUS_MICRO;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		i = data->ctrl_reg1 >> MAG3110_CTRL_DR_SHIFT;
 		*val = mag3110_samp_freq[i][0];
 		*val2 = mag3110_samp_freq[i][1];
 		return IIO_VAL_INT_PLUS_MICRO;
 	}
 	return -EINVAL;
 }

 static int mag3110_write_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     int val, int val2, long mask)
 {
 	struct mag3110_data *data = iio_priv(indio_dev);
 	int rate;

 	if (iio_buffer_enabled(indio_dev))
 		return -EBUSY;

 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		rate = mag3110_get_samp_freq_index(data, val, val2);
 		if (rate < 0)
 			return -EINVAL;

 		data->ctrl_reg1 &= ~MAG3110_CTRL_DR_MASK;
 		data->ctrl_reg1 |= rate << MAG3110_CTRL_DR_SHIFT;
 		return i2c_smbus_write_byte_data(data->client,
 			MAG3110_CTRL_REG1, data->ctrl_reg1);
 	default:
 		return -EINVAL;
 	}
 }

 static irqreturn_t mag3110_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct mag3110_data *data = iio_priv(indio_dev);
 	u8 buffer[16]; /* 3 16-bit channels + 1 byte temp + padding + ts */
 	int ret;

 	ret = mag3110_read(data, (__be16 *) buffer);
 	if (ret < 0)
 		goto done;

 	if (test_bit(3, indio_dev->active_scan_mask)) {
 		ret = i2c_smbus_read_byte_data(data->client,
 			MAG3110_DIE_TEMP);
 		if (ret < 0)
 			goto done;
 		buffer[6] = ret;
 	}

 	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
 		iio_get_time_ns());

 done:
 	iio_trigger_notify_done(indio_dev->trig);
 	return IRQ_HANDLED;
 }

 #define MAG3110_CHANNEL(axis, idx) { \
 	.type = IIO_MAGN, \
 	.modified = 1, \
 	.channel2 = IIO_MOD_##axis, \
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
 		BIT(IIO_CHAN_INFO_SCALE), \
 	.scan_index = idx, \
 	.scan_type = { \
 		.sign = 's', \
 		.realbits = 16, \
 		.storagebits = 16, \
 		.endianness = IIO_BE, \
 	}, \
 }

 static const struct iio_chan_spec mag3110_channels[] = {
 	MAG3110_CHANNEL(X, 0),
 	MAG3110_CHANNEL(Y, 1),
 	MAG3110_CHANNEL(Z, 2),
 	{
 		.type = IIO_TEMP,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.scan_index = 3,
 		.scan_type = {
 			.sign = 's',
 			.realbits = 8,
 			.storagebits = 8,
 			},
 	},
 	IIO_CHAN_SOFT_TIMESTAMP(4),
 };

 static struct attribute *mag3110_attributes[] = {
 	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group mag3110_group = {
 	.attrs = mag3110_attributes,
 };

 static const struct iio_info mag3110_info = {
 	.attrs = &mag3110_group,
 	.read_raw = &mag3110_read_raw,
 	.write_raw = &mag3110_write_raw,
 	.driver_module = THIS_MODULE,
 };

 static const unsigned long mag3110_scan_masks[] = {0x7, 0xf, 0};

 static int mag3110_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct mag3110_data *data;
 	struct iio_dev *indio_dev;
 	int ret;

 	ret = i2c_smbus_read_byte_data(client, MAG3110_WHO_AM_I);
 	if (ret < 0)
 		return ret;
 	if (ret != MAG3110_DEVICE_ID)
 		return -ENODEV;

 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
 		return -ENOMEM;

 	data = iio_priv(indio_dev);
 	data->client = client;
 	mutex_init(&data->lock);

 	i2c_set_clientdata(client, indio_dev);
 	indio_dev->info = &mag3110_info;
 	indio_dev->name = id->name;
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = mag3110_channels;
 	indio_dev->num_channels = ARRAY_SIZE(mag3110_channels);
 	indio_dev->available_scan_masks = mag3110_scan_masks;

 	data->ctrl_reg1 = MAG3110_CTRL_DR_DEFAULT;
 	ret = i2c_smbus_write_byte_data(client, MAG3110_CTRL_REG1,
 		data->ctrl_reg1);
 	if (ret < 0)
 		return ret;

 	ret = i2c_smbus_write_byte_data(client, MAG3110_CTRL_REG2,
 		MAG3110_CTRL_AUTO_MRST_EN | MAG3110_CTRL_RAW);
 	if (ret < 0)
 		return ret;

 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 		mag3110_trigger_handler, NULL);
 	if (ret < 0)
 		return ret;

 	ret = iio_device_register(indio_dev);
 	if (ret < 0)
 		goto buffer_cleanup;
 	return 0;

 buffer_cleanup:
 	iio_triggered_buffer_cleanup(indio_dev);
 	return ret;
 }

 static int mag3110_standby(struct mag3110_data *data)
 {
 	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
 		data->ctrl_reg1 & ~MAG3110_CTRL_AC);
 }

 static int mag3110_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);

 	iio_device_unregister(indio_dev);
 	iio_triggered_buffer_cleanup(indio_dev);
 	mag3110_standby(iio_priv(indio_dev));

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int mag3110_suspend(struct device *dev)
 {
 	return mag3110_standby(iio_priv(i2c_get_clientdata(
 		to_i2c_client(dev))));
 }

 static int mag3110_resume(struct device *dev)
 {
 	struct mag3110_data *data = iio_priv(i2c_get_clientdata(
 		to_i2c_client(dev)));

 	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
 		data->ctrl_reg1);
 }

 static SIMPLE_DEV_PM_OPS(mag3110_pm_ops, mag3110_suspend, mag3110_resume);
 #define MAG3110_PM_OPS (&mag3110_pm_ops)
 #else
 #define MAG3110_PM_OPS NULL
 #endif

 static const struct i2c_device_id mag3110_id[] = {
 	{ "mag3110", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, mag3110_id);

 static struct i2c_driver mag3110_driver = {
 	.driver = {
 		.name	= "mag3110",
 		.pm	= MAG3110_PM_OPS,
 	},
 	.probe = mag3110_probe,
 	.remove = mag3110_remove,
 	.id_table = mag3110_id,
 };
 module_i2c_driver(mag3110_driver);

 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
 MODULE_DESCRIPTION("Freescale MAG3110 magnetometer driver");
 MODULE_LICENSE("GPL");
	/*
	* mag3110.c - Support for Freescale MAG3110 magnetometer sensor
	*
	* Copyright (c) 2013 Peter Meerwald <pmeerw@pmeerw.net>
	*
	* This file is subject to the terms and conditions of version 2 of
	* the GNU General Public License. See the file COPYING in the main
	* directory of this archive for more details.
	*
	* (7-bit I2C slave address 0x0e)
	*
	* TODO: irq, user offset, oversampling, continuous mode
	*/

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/iio/trigger_consumer.h>
	#include <linux/iio/buffer.h>
	#include <linux/iio/triggered_buffer.h>
	#include <linux/delay.h>

	#define MAG3110_STATUS 0x00
	#define MAG3110_OUT_X 0x01 /* MSB first */
	#define MAG3110_OUT_Y 0x03
	#define MAG3110_OUT_Z 0x05
	#define MAG3110_WHO_AM_I 0x07
	#define MAG3110_OFF_X 0x09 /* MSB first */
	#define MAG3110_OFF_Y 0x0b
	#define MAG3110_OFF_Z 0x0d
	#define MAG3110_DIE_TEMP 0x0f
	#define MAG3110_CTRL_REG1 0x10
	#define MAG3110_CTRL_REG2 0x11

	#define MAG3110_STATUS_DRDY (BIT(2) \| BIT(1) \| BIT(0))

	#define MAG3110_CTRL_DR_MASK (BIT(7) \| BIT(6) \| BIT(5))
	#define MAG3110_CTRL_DR_SHIFT 5
	#define MAG3110_CTRL_DR_DEFAULT 0

	#define MAG3110_CTRL_TM BIT(1) /* trigger single measurement */
	#define MAG3110_CTRL_AC BIT(0) /* continuous measurements */

	#define MAG3110_CTRL_AUTO_MRST_EN BIT(7) /* magnetic auto-reset */
	#define MAG3110_CTRL_RAW BIT(5) /* measurements not user-offset corrected */

	#define MAG3110_DEVICE_ID 0xc4

	/* Each client has this additional data */
	struct mag3110_data {
	struct i2c_client *client;
	struct mutex lock;
	u8 ctrl_reg1;
	};

	static int mag3110_request(struct mag3110_data *data)
	{
	int ret, tries = 150;

	/* trigger measurement */
	ret = i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
	data->ctrl_reg1 \| MAG3110_CTRL_TM);
	if (ret < 0)
	return ret;

	while (tries-- > 0) {
	ret = i2c_smbus_read_byte_data(data->client, MAG3110_STATUS);
	if (ret < 0)
	return ret;
	/* wait for data ready */
	if ((ret & MAG3110_STATUS_DRDY) == MAG3110_STATUS_DRDY)
	break;
	msleep(20);
	}

	if (tries < 0) {
	dev_err(&data->client->dev, "data not ready\n");
	return -EIO;
	}

	return 0;
	}

	static int mag3110_read(struct mag3110_data *data, __be16 buf[3])
	{
	int ret;

	mutex_lock(&data->lock);
	ret = mag3110_request(data);
	if (ret < 0) {
	mutex_unlock(&data->lock);
	return ret;
	}
	ret = i2c_smbus_read_i2c_block_data(data->client,
	MAG3110_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
	mutex_unlock(&data->lock);

	return ret;
	}

	static ssize_t mag3110_show_int_plus_micros(char *buf,
	const int (*vals)[2], int n)
	{
	size_t len = 0;

	while (n-- > 0)
	len += scnprintf(buf + len, PAGE_SIZE - len,
	"%d.%06d ", vals[n][0], vals[n][1]);

	/* replace trailing space by newline */
	buf[len - 1] = '\n';

	return len;
	}

	static int mag3110_get_int_plus_micros_index(const int (*vals)[2], int n,
	int val, int val2)
	{
	while (n-- > 0)
	if (val == vals[n][0] && val2 == vals[n][1])
	return n;

	return -EINVAL;
	}

	static const int mag3110_samp_freq[8][2] = {
	{80, 0}, {40, 0}, {20, 0}, {10, 0}, {5, 0}, {2, 500000},
	{1, 250000}, {0, 625000}
	};

	static ssize_t mag3110_show_samp_freq_avail(struct device *dev,
	struct device_attribute attr, char buf)
	{
	return mag3110_show_int_plus_micros(buf, mag3110_samp_freq, 8);
	}

	static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mag3110_show_samp_freq_avail);

	static int mag3110_get_samp_freq_index(struct mag3110_data *data,
	int val, int val2)
	{
	return mag3110_get_int_plus_micros_index(mag3110_samp_freq, 8, val,
	val2);
	}

	static int mag3110_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct mag3110_data *data = iio_priv(indio_dev);
	__be16 buffer[3];
	int i, ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	if (iio_buffer_enabled(indio_dev))
	return -EBUSY;

	switch (chan->type) {
	case IIO_MAGN: /* in 0.1 uT / LSB */
	ret = mag3110_read(data, buffer);
	if (ret < 0)
	return ret;
	*val = sign_extend32(
	be16_to_cpu(buffer[chan->scan_index]), 15);
	return IIO_VAL_INT;
	case IIO_TEMP: /* in 1 C / LSB */
	mutex_lock(&data->lock);
	ret = mag3110_request(data);
	if (ret < 0) {
	mutex_unlock(&data->lock);
	return ret;
	}
	ret = i2c_smbus_read_byte_data(data->client,
	MAG3110_DIE_TEMP);
	mutex_unlock(&data->lock);
	if (ret < 0)
	return ret;
	*val = sign_extend32(ret, 7);
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	case IIO_CHAN_INFO_SCALE:
	*val = 0;
	*val2 = 1000;
	return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_SAMP_FREQ:
	i = data->ctrl_reg1 >> MAG3110_CTRL_DR_SHIFT;
	*val = mag3110_samp_freq[i][0];
	*val2 = mag3110_samp_freq[i][1];
	return IIO_VAL_INT_PLUS_MICRO;
	}
	return -EINVAL;
	}

	static int mag3110_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct mag3110_data *data = iio_priv(indio_dev);
	int rate;

	if (iio_buffer_enabled(indio_dev))
	return -EBUSY;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
	rate = mag3110_get_samp_freq_index(data, val, val2);
	if (rate < 0)
	return -EINVAL;

	data->ctrl_reg1 &= ~MAG3110_CTRL_DR_MASK;
	data->ctrl_reg1 \|= rate << MAG3110_CTRL_DR_SHIFT;
	return i2c_smbus_write_byte_data(data->client,
	MAG3110_CTRL_REG1, data->ctrl_reg1);
	default:
	return -EINVAL;
	}
	}

	static irqreturn_t mag3110_trigger_handler(int irq, void *p)
	{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct mag3110_data *data = iio_priv(indio_dev);
	u8 buffer[16]; /* 3 16-bit channels + 1 byte temp + padding + ts */
	int ret;

	ret = mag3110_read(data, (__be16 *) buffer);
	if (ret < 0)
	goto done;

	if (test_bit(3, indio_dev->active_scan_mask)) {
	ret = i2c_smbus_read_byte_data(data->client,
	MAG3110_DIE_TEMP);
	if (ret < 0)
	goto done;
	buffer[6] = ret;
	}

	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
	iio_get_time_ns());

	done:
	iio_trigger_notify_done(indio_dev->trig);
	return IRQ_HANDLED;
	}

	#define MAG3110_CHANNEL(axis, idx) { \
	.type = IIO_MAGN, \
	.modified = 1, \
	.channel2 = IIO_MOD_##axis, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) \| \
	BIT(IIO_CHAN_INFO_SCALE), \
	.scan_index = idx, \
	.scan_type = { \
	.sign = 's', \
	.realbits = 16, \
	.storagebits = 16, \
	.endianness = IIO_BE, \
	}, \
	}

	static const struct iio_chan_spec mag3110_channels[] = {
	MAG3110_CHANNEL(X, 0),
	MAG3110_CHANNEL(Y, 1),
	MAG3110_CHANNEL(Z, 2),
	{
	.type = IIO_TEMP,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
	.scan_index = 3,
	.scan_type = {
	.sign = 's',
	.realbits = 8,
	.storagebits = 8,
	},
	},
	IIO_CHAN_SOFT_TIMESTAMP(4),
	};

	static struct attribute *mag3110_attributes[] = {
	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
	NULL
	};

	static const struct attribute_group mag3110_group = {
	.attrs = mag3110_attributes,
	};

	static const struct iio_info mag3110_info = {
	.attrs = &mag3110_group,
	.read_raw = &mag3110_read_raw,
	.write_raw = &mag3110_write_raw,
	.driver_module = THIS_MODULE,
	};

	static const unsigned long mag3110_scan_masks[] = {0x7, 0xf, 0};

	static int mag3110_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct mag3110_data *data;
	struct iio_dev *indio_dev;
	int ret;

	ret = i2c_smbus_read_byte_data(client, MAG3110_WHO_AM_I);
	if (ret < 0)
	return ret;
	if (ret != MAG3110_DEVICE_ID)
	return -ENODEV;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (!indio_dev)
	return -ENOMEM;

	data = iio_priv(indio_dev);
	data->client = client;
	mutex_init(&data->lock);

	i2c_set_clientdata(client, indio_dev);
	indio_dev->info = &mag3110_info;
	indio_dev->name = id->name;
	indio_dev->dev.parent = &client->dev;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = mag3110_channels;
	indio_dev->num_channels = ARRAY_SIZE(mag3110_channels);
	indio_dev->available_scan_masks = mag3110_scan_masks;

	data->ctrl_reg1 = MAG3110_CTRL_DR_DEFAULT;
	ret = i2c_smbus_write_byte_data(client, MAG3110_CTRL_REG1,
	data->ctrl_reg1);
	if (ret < 0)
	return ret;

	ret = i2c_smbus_write_byte_data(client, MAG3110_CTRL_REG2,
	MAG3110_CTRL_AUTO_MRST_EN \| MAG3110_CTRL_RAW);
	if (ret < 0)
	return ret;

	ret = iio_triggered_buffer_setup(indio_dev, NULL,
	mag3110_trigger_handler, NULL);
	if (ret < 0)
	return ret;

	ret = iio_device_register(indio_dev);
	if (ret < 0)
	goto buffer_cleanup;
	return 0;

	buffer_cleanup:
	iio_triggered_buffer_cleanup(indio_dev);
	return ret;
	}

	static int mag3110_standby(struct mag3110_data *data)
	{
	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
	data->ctrl_reg1 & ~MAG3110_CTRL_AC);
	}

	static int mag3110_remove(struct i2c_client *client)
	{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);

	iio_device_unregister(indio_dev);
	iio_triggered_buffer_cleanup(indio_dev);
	mag3110_standby(iio_priv(indio_dev));

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int mag3110_suspend(struct device *dev)
	{
	return mag3110_standby(iio_priv(i2c_get_clientdata(
	to_i2c_client(dev))));
	}

	static int mag3110_resume(struct device *dev)
	{
	struct mag3110_data *data = iio_priv(i2c_get_clientdata(
	to_i2c_client(dev)));

	return i2c_smbus_write_byte_data(data->client, MAG3110_CTRL_REG1,
	data->ctrl_reg1);
	}

	static SIMPLE_DEV_PM_OPS(mag3110_pm_ops, mag3110_suspend, mag3110_resume);
	#define MAG3110_PM_OPS (&mag3110_pm_ops)
	#else
	#define MAG3110_PM_OPS NULL
	#endif

	static const struct i2c_device_id mag3110_id[] = {
	{ "mag3110", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, mag3110_id);

	static struct i2c_driver mag3110_driver = {
	.driver = {
	.name = "mag3110",
	.pm = MAG3110_PM_OPS,
	},
	.probe = mag3110_probe,
	.remove = mag3110_remove,
	.id_table = mag3110_id,
	};
	module_i2c_driver(mag3110_driver);

	MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
	MODULE_DESCRIPTION("Freescale MAG3110 magnetometer driver");
	MODULE_LICENSE("GPL");