drivers/iio/proximity/srf08.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * srf08.c - Support for Devantech SRF08 ultrasonic ranger
  *
  * Copyright (c) 2016 Andreas Klinger <ak@it-klinger.de>
  *
  * 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.
  *
  * For details about the device see:
  * http://www.robot-electronics.co.uk/htm/srf08tech.html
  */

 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/bitops.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>

 /* registers of SRF08 device */
 #define SRF08_WRITE_COMMAND	0x00	/* Command Register */
 #define SRF08_WRITE_MAX_GAIN	0x01	/* Max Gain Register: 0 .. 31 */
 #define SRF08_WRITE_RANGE	0x02	/* Range Register: 0 .. 255 */
 #define SRF08_READ_SW_REVISION	0x00	/* Software Revision */
 #define SRF08_READ_LIGHT	0x01	/* Light Sensor during last echo */
 #define SRF08_READ_ECHO_1_HIGH	0x02	/* Range of first echo received */
 #define SRF08_READ_ECHO_1_LOW	0x03	/* Range of first echo received */

 #define SRF08_CMD_RANGING_CM	0x51	/* Ranging Mode - Result in cm */

 #define SRF08_DEFAULT_GAIN	1025	/* default analogue value of Gain */
 #define SRF08_DEFAULT_RANGE	6020	/* default value of Range in mm */

 struct srf08_data {
 	struct i2c_client	*client;
 	int			sensitivity;		/* Gain */
 	int			range_mm;		/* max. Range in mm */
 	struct mutex		lock;
 };

 /*
  * in the documentation one can read about the "Gain" of the device
  * which is used here for amplifying the signal and filtering out unwanted
  * ones.
  * But with ADC's this term is already used differently and that's why it
  * is called "Sensitivity" here.
  */
 static const int srf08_sensitivity[] = {
 	 94,  97, 100, 103, 107, 110, 114, 118,
 	123, 128, 133, 139, 145, 152, 159, 168,
 	177, 187, 199, 212, 227, 245, 265, 288,
 	317, 352, 395, 450, 524, 626, 777, 1025 };

 static int srf08_read_ranging(struct srf08_data *data)
 {
 	struct i2c_client *client = data->client;
 	int ret, i;
 	int waittime;

 	mutex_lock(&data->lock);

 	ret = i2c_smbus_write_byte_data(data->client,
 			SRF08_WRITE_COMMAND, SRF08_CMD_RANGING_CM);
 	if (ret < 0) {
 		dev_err(&client->dev, "write command - err: %d\n", ret);
 		mutex_unlock(&data->lock);
 		return ret;
 	}

 	/*
 	 * we read here until a correct version number shows up as
 	 * suggested by the documentation
 	 *
 	 * with an ultrasonic speed of 343 m/s and a roundtrip of it
 	 * sleep the expected duration and try to read from the device
 	 * if nothing useful is read try it in a shorter grid
 	 *
 	 * polling for not more than 20 ms should be enough
 	 */
 	waittime = 1 + data->range_mm / 172;
 	msleep(waittime);
 	for (i = 0; i < 4; i++) {
 		ret = i2c_smbus_read_byte_data(data->client,
 						SRF08_READ_SW_REVISION);

 		/* check if a valid version number is read */
 		if (ret < 255 && ret > 0)
 			break;
 		msleep(5);
 	}

 	if (ret >= 255 || ret <= 0) {
 		dev_err(&client->dev, "device not ready\n");
 		mutex_unlock(&data->lock);
 		return -EIO;
 	}

 	ret = i2c_smbus_read_word_swapped(data->client,
 						SRF08_READ_ECHO_1_HIGH);
 	if (ret < 0) {
 		dev_err(&client->dev, "cannot read distance: ret=%d\n", ret);
 		mutex_unlock(&data->lock);
 		return ret;
 	}

 	mutex_unlock(&data->lock);

 	return ret;
 }

 static int srf08_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *channel, int *val,
 			    int *val2, long mask)
 {
 	struct srf08_data *data = iio_priv(indio_dev);
 	int ret;

 	if (channel->type != IIO_DISTANCE)
 		return -EINVAL;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		ret = srf08_read_ranging(data);
 		if (ret < 0)
 			return ret;
 		*val = ret;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		/* 1 LSB is 1 cm */
 		*val = 0;
 		*val2 = 10000;
 		return IIO_VAL_INT_PLUS_MICRO;
 	default:
 		return -EINVAL;
 	}
 }

 static ssize_t srf08_show_range_mm_available(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	return sprintf(buf, "[0.043 0.043 11.008]\n");
 }

 static IIO_DEVICE_ATTR(sensor_max_range_available, S_IRUGO,
 				srf08_show_range_mm_available, NULL, 0);

 static ssize_t srf08_show_range_mm(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct srf08_data *data = iio_priv(indio_dev);

 	return sprintf(buf, "%d.%03d\n", data->range_mm / 1000,
 						data->range_mm % 1000);
 }

 /*
  * set the range of the sensor to an even multiple of 43 mm
  * which corresponds to 1 LSB in the register
  *
  * register value    corresponding range
  *         0x00             43 mm
  *         0x01             86 mm
  *         0x02            129 mm
  *         ...
  *         0xFF          11008 mm
  */
 static ssize_t srf08_write_range_mm(struct srf08_data *data, unsigned int val)
 {
 	int ret;
 	struct i2c_client *client = data->client;
 	unsigned int mod;
 	u8 regval;

 	ret = val / 43 - 1;
 	mod = val % 43;

 	if (mod || (ret < 0) || (ret > 255))
 		return -EINVAL;

 	regval = ret;

 	mutex_lock(&data->lock);

 	ret = i2c_smbus_write_byte_data(client, SRF08_WRITE_RANGE, regval);
 	if (ret < 0) {
 		dev_err(&client->dev, "write_range - err: %d\n", ret);
 		mutex_unlock(&data->lock);
 		return ret;
 	}

 	data->range_mm = val;

 	mutex_unlock(&data->lock);

 	return 0;
 }

 static ssize_t srf08_store_range_mm(struct device *dev,
 					struct device_attribute *attr,
 					const char *buf, size_t len)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct srf08_data *data = iio_priv(indio_dev);
 	int ret;
 	int integer, fract;

 	ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
 	if (ret)
 		return ret;

 	ret = srf08_write_range_mm(data, integer * 1000 + fract);
 	if (ret < 0)
 		return ret;

 	return len;
 }

 static IIO_DEVICE_ATTR(sensor_max_range, S_IRUGO | S_IWUSR,
 			srf08_show_range_mm, srf08_store_range_mm, 0);

 static ssize_t srf08_show_sensitivity_available(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	int i, len = 0;

 	for (i = 0; i < ARRAY_SIZE(srf08_sensitivity); i++)
 		len += sprintf(buf + len, "%d ", srf08_sensitivity[i]);

 	len += sprintf(buf + len, "\n");

 	return len;
 }

 static IIO_DEVICE_ATTR(sensor_sensitivity_available, S_IRUGO,
 				srf08_show_sensitivity_available, NULL, 0);

 static ssize_t srf08_show_sensitivity(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct srf08_data *data = iio_priv(indio_dev);
 	int len;

 	len = sprintf(buf, "%d\n", data->sensitivity);

 	return len;
 }

 static ssize_t srf08_write_sensitivity(struct srf08_data *data,
 							unsigned int val)
 {
 	struct i2c_client *client = data->client;
 	int ret, i;
 	u8 regval;

 	for (i = 0; i < ARRAY_SIZE(srf08_sensitivity); i++)
 		if (val == srf08_sensitivity[i]) {
 			regval = i;
 			break;
 		}

 	if (i >= ARRAY_SIZE(srf08_sensitivity))
 		return -EINVAL;

 	mutex_lock(&data->lock);

 	ret = i2c_smbus_write_byte_data(client,
 						SRF08_WRITE_MAX_GAIN, regval);
 	if (ret < 0) {
 		dev_err(&client->dev, "write_sensitivity - err: %d\n", ret);
 		mutex_unlock(&data->lock);
 		return ret;
 	}

 	data->sensitivity = val;

 	mutex_unlock(&data->lock);

 	return 0;
 }

 static ssize_t srf08_store_sensitivity(struct device *dev,
 						struct device_attribute *attr,
 						const char *buf, size_t len)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct srf08_data *data = iio_priv(indio_dev);
 	int ret;
 	unsigned int val;

 	ret = kstrtouint(buf, 10, &val);
 	if (ret)
 		return ret;

 	ret = srf08_write_sensitivity(data, val);
 	if (ret < 0)
 		return ret;

 	return len;
 }

 static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO | S_IWUSR,
 			srf08_show_sensitivity, srf08_store_sensitivity, 0);

 static struct attribute *srf08_attributes[] = {
 	&iio_dev_attr_sensor_max_range.dev_attr.attr,
 	&iio_dev_attr_sensor_max_range_available.dev_attr.attr,
 	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
 	&iio_dev_attr_sensor_sensitivity_available.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group srf08_attribute_group = {
 	.attrs = srf08_attributes,
 };

 static const struct iio_chan_spec srf08_channels[] = {
 	{
 		.type = IIO_DISTANCE,
 		.info_mask_separate =
 				BIT(IIO_CHAN_INFO_RAW) |
 				BIT(IIO_CHAN_INFO_SCALE),
 	},
 };

 static const struct iio_info srf08_info = {
 	.read_raw = srf08_read_raw,
 	.attrs = &srf08_attribute_group,
 	.driver_module = THIS_MODULE,
 };

 static int srf08_probe(struct i2c_client *client,
 					 const struct i2c_device_id *id)
 {
 	struct iio_dev *indio_dev;
 	struct srf08_data *data;
 	int ret;

 	if (!i2c_check_functionality(client->adapter,
 					I2C_FUNC_SMBUS_READ_BYTE_DATA |
 					I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
 					I2C_FUNC_SMBUS_READ_WORD_DATA))
 		return -ENODEV;

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

 	data = iio_priv(indio_dev);
 	i2c_set_clientdata(client, indio_dev);
 	data->client = client;

 	indio_dev->name = "srf08";
 	indio_dev->dev.parent = &client->dev;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->info = &srf08_info;
 	indio_dev->channels = srf08_channels;
 	indio_dev->num_channels = ARRAY_SIZE(srf08_channels);

 	mutex_init(&data->lock);

 	/*
 	 * set default values of device here
 	 * these register values cannot be read from the hardware
 	 * therefore set driver specific default values
 	 */
 	ret = srf08_write_range_mm(data, SRF08_DEFAULT_RANGE);
 	if (ret < 0)
 		return ret;

 	ret = srf08_write_sensitivity(data, SRF08_DEFAULT_GAIN);
 	if (ret < 0)
 		return ret;

 	return devm_iio_device_register(&client->dev, indio_dev);
 }

 static const struct i2c_device_id srf08_id[] = {
 	{ "srf08", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, srf08_id);

 static struct i2c_driver srf08_driver = {
 	.driver = {
 		.name	= "srf08",
 	},
 	.probe = srf08_probe,
 	.id_table = srf08_id,
 };
 module_i2c_driver(srf08_driver);

 MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
 MODULE_DESCRIPTION("Devantech SRF08 ultrasonic ranger driver");
 MODULE_LICENSE("GPL");
	/*
	* srf08.c - Support for Devantech SRF08 ultrasonic ranger
	*
	* Copyright (c) 2016 Andreas Klinger <ak@it-klinger.de>
	*
	* 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.
	*
	* For details about the device see:
	* http://www.robot-electronics.co.uk/htm/srf08tech.html
	*/

	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/delay.h>
	#include <linux/module.h>
	#include <linux/bitops.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>

	/* registers of SRF08 device */
	#define SRF08_WRITE_COMMAND 0x00 /* Command Register */
	#define SRF08_WRITE_MAX_GAIN 0x01 /* Max Gain Register: 0 .. 31 */
	#define SRF08_WRITE_RANGE 0x02 /* Range Register: 0 .. 255 */
	#define SRF08_READ_SW_REVISION 0x00 /* Software Revision */
	#define SRF08_READ_LIGHT 0x01 /* Light Sensor during last echo */
	#define SRF08_READ_ECHO_1_HIGH 0x02 /* Range of first echo received */
	#define SRF08_READ_ECHO_1_LOW 0x03 /* Range of first echo received */

	#define SRF08_CMD_RANGING_CM 0x51 /* Ranging Mode - Result in cm */

	#define SRF08_DEFAULT_GAIN 1025 /* default analogue value of Gain */
	#define SRF08_DEFAULT_RANGE 6020 /* default value of Range in mm */

	struct srf08_data {
	struct i2c_client *client;
	int sensitivity; /* Gain */
	int range_mm; /* max. Range in mm */
	struct mutex lock;
	};

	/*
	* in the documentation one can read about the "Gain" of the device
	* which is used here for amplifying the signal and filtering out unwanted
	* ones.
	* But with ADC's this term is already used differently and that's why it
	* is called "Sensitivity" here.
	*/
	static const int srf08_sensitivity[] = {
	94, 97, 100, 103, 107, 110, 114, 118,
	123, 128, 133, 139, 145, 152, 159, 168,
	177, 187, 199, 212, 227, 245, 265, 288,
	317, 352, 395, 450, 524, 626, 777, 1025 };

	static int srf08_read_ranging(struct srf08_data *data)
	{
	struct i2c_client *client = data->client;
	int ret, i;
	int waittime;

	mutex_lock(&data->lock);

	ret = i2c_smbus_write_byte_data(data->client,
	SRF08_WRITE_COMMAND, SRF08_CMD_RANGING_CM);
	if (ret < 0) {
	dev_err(&client->dev, "write command - err: %d\n", ret);
	mutex_unlock(&data->lock);
	return ret;
	}

	/*
	* we read here until a correct version number shows up as
	* suggested by the documentation
	*
	* with an ultrasonic speed of 343 m/s and a roundtrip of it
	* sleep the expected duration and try to read from the device
	* if nothing useful is read try it in a shorter grid
	*
	* polling for not more than 20 ms should be enough
	*/
	waittime = 1 + data->range_mm / 172;
	msleep(waittime);
	for (i = 0; i < 4; i++) {
	ret = i2c_smbus_read_byte_data(data->client,
	SRF08_READ_SW_REVISION);

	/* check if a valid version number is read */
	if (ret < 255 && ret > 0)
	break;
	msleep(5);
	}

	if (ret >= 255 \|\| ret <= 0) {
	dev_err(&client->dev, "device not ready\n");
	mutex_unlock(&data->lock);
	return -EIO;
	}

	ret = i2c_smbus_read_word_swapped(data->client,
	SRF08_READ_ECHO_1_HIGH);
	if (ret < 0) {
	dev_err(&client->dev, "cannot read distance: ret=%d\n", ret);
	mutex_unlock(&data->lock);
	return ret;
	}

	mutex_unlock(&data->lock);

	return ret;
	}

	static int srf08_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const channel, int val,
	int *val2, long mask)
	{
	struct srf08_data *data = iio_priv(indio_dev);
	int ret;

	if (channel->type != IIO_DISTANCE)
	return -EINVAL;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	ret = srf08_read_ranging(data);
	if (ret < 0)
	return ret;
	*val = ret;
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	/* 1 LSB is 1 cm */
	*val = 0;
	*val2 = 10000;
	return IIO_VAL_INT_PLUS_MICRO;
	default:
	return -EINVAL;
	}
	}

	static ssize_t srf08_show_range_mm_available(struct device *dev,
	struct device_attribute attr, char buf)
	{
	return sprintf(buf, "[0.043 0.043 11.008]\n");
	}

	static IIO_DEVICE_ATTR(sensor_max_range_available, S_IRUGO,
	srf08_show_range_mm_available, NULL, 0);

	static ssize_t srf08_show_range_mm(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct srf08_data *data = iio_priv(indio_dev);

	return sprintf(buf, "%d.%03d\n", data->range_mm / 1000,
	data->range_mm % 1000);
	}

	/*
	* set the range of the sensor to an even multiple of 43 mm
	* which corresponds to 1 LSB in the register
	*
	* register value corresponding range
	* 0x00 43 mm
	* 0x01 86 mm
	* 0x02 129 mm
	* ...
	* 0xFF 11008 mm
	*/
	static ssize_t srf08_write_range_mm(struct srf08_data *data, unsigned int val)
	{
	int ret;
	struct i2c_client *client = data->client;
	unsigned int mod;
	u8 regval;

	ret = val / 43 - 1;
	mod = val % 43;

	if (mod \|\| (ret < 0) \|\| (ret > 255))
	return -EINVAL;

	regval = ret;

	mutex_lock(&data->lock);

	ret = i2c_smbus_write_byte_data(client, SRF08_WRITE_RANGE, regval);
	if (ret < 0) {
	dev_err(&client->dev, "write_range - err: %d\n", ret);
	mutex_unlock(&data->lock);
	return ret;
	}

	data->range_mm = val;

	mutex_unlock(&data->lock);

	return 0;
	}

	static ssize_t srf08_store_range_mm(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t len)
	{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct srf08_data *data = iio_priv(indio_dev);
	int ret;
	int integer, fract;

	ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
	if (ret)
	return ret;

	ret = srf08_write_range_mm(data, integer * 1000 + fract);
	if (ret < 0)
	return ret;

	return len;
	}

	static IIO_DEVICE_ATTR(sensor_max_range, S_IRUGO \| S_IWUSR,
	srf08_show_range_mm, srf08_store_range_mm, 0);

	static ssize_t srf08_show_sensitivity_available(struct device *dev,
	struct device_attribute attr, char buf)
	{
	int i, len = 0;

	for (i = 0; i < ARRAY_SIZE(srf08_sensitivity); i++)
	len += sprintf(buf + len, "%d ", srf08_sensitivity[i]);

	len += sprintf(buf + len, "\n");

	return len;
	}

	static IIO_DEVICE_ATTR(sensor_sensitivity_available, S_IRUGO,
	srf08_show_sensitivity_available, NULL, 0);

	static ssize_t srf08_show_sensitivity(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct srf08_data *data = iio_priv(indio_dev);
	int len;

	len = sprintf(buf, "%d\n", data->sensitivity);

	return len;
	}

	static ssize_t srf08_write_sensitivity(struct srf08_data *data,
	unsigned int val)
	{
	struct i2c_client *client = data->client;
	int ret, i;
	u8 regval;

	for (i = 0; i < ARRAY_SIZE(srf08_sensitivity); i++)
	if (val == srf08_sensitivity[i]) {
	regval = i;
	break;
	}

	if (i >= ARRAY_SIZE(srf08_sensitivity))
	return -EINVAL;

	mutex_lock(&data->lock);

	ret = i2c_smbus_write_byte_data(client,
	SRF08_WRITE_MAX_GAIN, regval);
	if (ret < 0) {
	dev_err(&client->dev, "write_sensitivity - err: %d\n", ret);
	mutex_unlock(&data->lock);
	return ret;
	}

	data->sensitivity = val;

	mutex_unlock(&data->lock);

	return 0;
	}

	static ssize_t srf08_store_sensitivity(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t len)
	{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct srf08_data *data = iio_priv(indio_dev);
	int ret;
	unsigned int val;

	ret = kstrtouint(buf, 10, &val);
	if (ret)
	return ret;

	ret = srf08_write_sensitivity(data, val);
	if (ret < 0)
	return ret;

	return len;
	}

	static IIO_DEVICE_ATTR(sensor_sensitivity, S_IRUGO \| S_IWUSR,
	srf08_show_sensitivity, srf08_store_sensitivity, 0);

	static struct attribute *srf08_attributes[] = {
	&iio_dev_attr_sensor_max_range.dev_attr.attr,
	&iio_dev_attr_sensor_max_range_available.dev_attr.attr,
	&iio_dev_attr_sensor_sensitivity.dev_attr.attr,
	&iio_dev_attr_sensor_sensitivity_available.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group srf08_attribute_group = {
	.attrs = srf08_attributes,
	};

	static const struct iio_chan_spec srf08_channels[] = {
	{
	.type = IIO_DISTANCE,
	.info_mask_separate =
	BIT(IIO_CHAN_INFO_RAW) \|
	BIT(IIO_CHAN_INFO_SCALE),
	},
	};

	static const struct iio_info srf08_info = {
	.read_raw = srf08_read_raw,
	.attrs = &srf08_attribute_group,
	.driver_module = THIS_MODULE,
	};

	static int srf08_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct iio_dev *indio_dev;
	struct srf08_data *data;
	int ret;

	if (!i2c_check_functionality(client->adapter,
	I2C_FUNC_SMBUS_READ_BYTE_DATA \|
	I2C_FUNC_SMBUS_WRITE_BYTE_DATA \|
	I2C_FUNC_SMBUS_READ_WORD_DATA))
	return -ENODEV;

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

	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);
	data->client = client;

	indio_dev->name = "srf08";
	indio_dev->dev.parent = &client->dev;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &srf08_info;
	indio_dev->channels = srf08_channels;
	indio_dev->num_channels = ARRAY_SIZE(srf08_channels);

	mutex_init(&data->lock);

	/*
	* set default values of device here
	* these register values cannot be read from the hardware
	* therefore set driver specific default values
	*/
	ret = srf08_write_range_mm(data, SRF08_DEFAULT_RANGE);
	if (ret < 0)
	return ret;

	ret = srf08_write_sensitivity(data, SRF08_DEFAULT_GAIN);
	if (ret < 0)
	return ret;

	return devm_iio_device_register(&client->dev, indio_dev);
	}

	static const struct i2c_device_id srf08_id[] = {
	{ "srf08", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, srf08_id);

	static struct i2c_driver srf08_driver = {
	.driver = {
	.name = "srf08",
	},
	.probe = srf08_probe,
	.id_table = srf08_id,
	};
	module_i2c_driver(srf08_driver);

	MODULE_AUTHOR("Andreas Klinger <ak@it-klinger.de>");
	MODULE_DESCRIPTION("Devantech SRF08 ultrasonic ranger driver");
	MODULE_LICENSE("GPL");