drivers/iio/pressure/hp206c.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * hp206c.c - HOPERF HP206C precision barometer and altimeter sensor
  *
  * Copyright (c) 2016, Intel Corporation.
  *
  * (7-bit I2C slave address 0x76)
  *
  * Datasheet:
  *  http://www.hoperf.com/upload/sensor/HP206C_DataSheet_EN_V2.0.pdf
  */

 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/delay.h>
 #include <linux/util_macros.h>

 #include <linux/unaligned.h>

 /* I2C commands: */
 #define HP206C_CMD_SOFT_RST	0x06

 #define HP206C_CMD_ADC_CVT	0x40

 #define HP206C_CMD_ADC_CVT_OSR_4096	0x00
 #define HP206C_CMD_ADC_CVT_OSR_2048	0x04
 #define HP206C_CMD_ADC_CVT_OSR_1024	0x08
 #define HP206C_CMD_ADC_CVT_OSR_512	0x0c
 #define HP206C_CMD_ADC_CVT_OSR_256	0x10
 #define HP206C_CMD_ADC_CVT_OSR_128	0x14

 #define HP206C_CMD_ADC_CVT_CHNL_PT	0x00
 #define HP206C_CMD_ADC_CVT_CHNL_T	0x02

 #define HP206C_CMD_READ_P	0x30
 #define HP206C_CMD_READ_T	0x32

 #define HP206C_CMD_READ_REG	0x80
 #define HP206C_CMD_WRITE_REG	0xc0

 #define HP206C_REG_INT_EN	0x0b
 #define HP206C_REG_INT_CFG	0x0c

 #define HP206C_REG_INT_SRC	0x0d
 #define HP206C_FLAG_DEV_RDY	0x40

 #define HP206C_REG_PARA		0x0f
 #define HP206C_FLAG_CMPS_EN	0x80

 /* Maximum spin for DEV_RDY */
 #define HP206C_MAX_DEV_RDY_WAIT_COUNT 20
 #define HP206C_DEV_RDY_WAIT_US    20000

 struct hp206c_data {
 	struct mutex mutex;
 	struct i2c_client *client;
 	int temp_osr_index;
 	int pres_osr_index;
 };

 struct hp206c_osr_setting {
 	u8 osr_mask;
 	unsigned int temp_conv_time_us;
 	unsigned int pres_conv_time_us;
 };

 /* Data from Table 5 in datasheet. */
 static const struct hp206c_osr_setting hp206c_osr_settings[] = {
 	{ HP206C_CMD_ADC_CVT_OSR_4096,	65600,	131100	},
 	{ HP206C_CMD_ADC_CVT_OSR_2048,	32800,	65600	},
 	{ HP206C_CMD_ADC_CVT_OSR_1024,	16400,	32800	},
 	{ HP206C_CMD_ADC_CVT_OSR_512,	8200,	16400	},
 	{ HP206C_CMD_ADC_CVT_OSR_256,	4100,	8200	},
 	{ HP206C_CMD_ADC_CVT_OSR_128,	2100,	4100	},
 };
 static const int hp206c_osr_rates[] = { 4096, 2048, 1024, 512, 256, 128 };
 static const char hp206c_osr_rates_str[] = "4096 2048 1024 512 256 128";

 static inline int hp206c_read_reg(struct i2c_client *client, u8 reg)
 {
 	return i2c_smbus_read_byte_data(client, HP206C_CMD_READ_REG | reg);
 }

 static inline int hp206c_write_reg(struct i2c_client *client, u8 reg, u8 val)
 {
 	return i2c_smbus_write_byte_data(client,
 			HP206C_CMD_WRITE_REG | reg, val);
 }

 static int hp206c_read_20bit(struct i2c_client *client, u8 cmd)
 {
 	int ret;
 	u8 values[3];

 	ret = i2c_smbus_read_i2c_block_data(client, cmd, sizeof(values), values);
 	if (ret < 0)
 		return ret;
 	if (ret != sizeof(values))
 		return -EIO;
 	return get_unaligned_be24(&values[0]) & GENMASK(19, 0);
 }

 /* Spin for max 160ms until DEV_RDY is 1, or return error. */
 static int hp206c_wait_dev_rdy(struct iio_dev *indio_dev)
 {
 	int ret;
 	int count = 0;
 	struct hp206c_data *data = iio_priv(indio_dev);
 	struct i2c_client *client = data->client;

 	while (++count <= HP206C_MAX_DEV_RDY_WAIT_COUNT) {
 		ret = hp206c_read_reg(client, HP206C_REG_INT_SRC);
 		if (ret < 0) {
 			dev_err(&indio_dev->dev, "Failed READ_REG INT_SRC: %d\n", ret);
 			return ret;
 		}
 		if (ret & HP206C_FLAG_DEV_RDY)
 			return 0;
 		usleep_range(HP206C_DEV_RDY_WAIT_US, HP206C_DEV_RDY_WAIT_US * 3 / 2);
 	}
 	return -ETIMEDOUT;
 }

 static int hp206c_set_compensation(struct i2c_client *client, bool enabled)
 {
 	int val;

 	val = hp206c_read_reg(client, HP206C_REG_PARA);
 	if (val < 0)
 		return val;
 	if (enabled)
 		val |= HP206C_FLAG_CMPS_EN;
 	else
 		val &= ~HP206C_FLAG_CMPS_EN;

 	return hp206c_write_reg(client, HP206C_REG_PARA, val);
 }

 /* Do a soft reset */
 static int hp206c_soft_reset(struct iio_dev *indio_dev)
 {
 	int ret;
 	struct hp206c_data *data = iio_priv(indio_dev);
 	struct i2c_client *client = data->client;

 	ret = i2c_smbus_write_byte(client, HP206C_CMD_SOFT_RST);
 	if (ret) {
 		dev_err(&client->dev, "Failed to reset device: %d\n", ret);
 		return ret;
 	}

 	usleep_range(400, 600);

 	ret = hp206c_wait_dev_rdy(indio_dev);
 	if (ret) {
 		dev_err(&client->dev, "Device not ready after soft reset: %d\n", ret);
 		return ret;
 	}

 	ret = hp206c_set_compensation(client, true);
 	if (ret)
 		dev_err(&client->dev, "Failed to enable compensation: %d\n", ret);
 	return ret;
 }

 static int hp206c_conv_and_read(struct iio_dev *indio_dev,
 				u8 conv_cmd, u8 read_cmd,
 				unsigned int sleep_us)
 {
 	int ret;
 	struct hp206c_data *data = iio_priv(indio_dev);
 	struct i2c_client *client = data->client;

 	ret = hp206c_wait_dev_rdy(indio_dev);
 	if (ret < 0) {
 		dev_err(&indio_dev->dev, "Device not ready: %d\n", ret);
 		return ret;
 	}

 	ret = i2c_smbus_write_byte(client, conv_cmd);
 	if (ret < 0) {
 		dev_err(&indio_dev->dev, "Failed convert: %d\n", ret);
 		return ret;
 	}

 	usleep_range(sleep_us, sleep_us * 3 / 2);

 	ret = hp206c_wait_dev_rdy(indio_dev);
 	if (ret < 0) {
 		dev_err(&indio_dev->dev, "Device not ready: %d\n", ret);
 		return ret;
 	}

 	ret = hp206c_read_20bit(client, read_cmd);
 	if (ret < 0)
 		dev_err(&indio_dev->dev, "Failed read: %d\n", ret);

 	return ret;
 }

 static int hp206c_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan, int *val,
 			   int *val2, long mask)
 {
 	int ret;
 	struct hp206c_data *data = iio_priv(indio_dev);
 	const struct hp206c_osr_setting *osr_setting;
 	u8 conv_cmd;

 	mutex_lock(&data->mutex);

 	switch (mask) {
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
 		switch (chan->type) {
 		case IIO_TEMP:
 			*val = hp206c_osr_rates[data->temp_osr_index];
 			ret = IIO_VAL_INT;
 			break;

 		case IIO_PRESSURE:
 			*val = hp206c_osr_rates[data->pres_osr_index];
 			ret = IIO_VAL_INT;
 			break;
 		default:
 			ret = -EINVAL;
 		}
 		break;

 	case IIO_CHAN_INFO_RAW:
 		switch (chan->type) {
 		case IIO_TEMP:
 			osr_setting = &hp206c_osr_settings[data->temp_osr_index];
 			conv_cmd = HP206C_CMD_ADC_CVT |
 					osr_setting->osr_mask |
 					HP206C_CMD_ADC_CVT_CHNL_T;
 			ret = hp206c_conv_and_read(indio_dev,
 					conv_cmd,
 					HP206C_CMD_READ_T,
 					osr_setting->temp_conv_time_us);
 			if (ret >= 0) {
 				/* 20 significant bits are provided.
 				 * Extend sign over the rest.
 				 */
 				*val = sign_extend32(ret, 19);
 				ret = IIO_VAL_INT;
 			}
 			break;

 		case IIO_PRESSURE:
 			osr_setting = &hp206c_osr_settings[data->pres_osr_index];
 			conv_cmd = HP206C_CMD_ADC_CVT |
 					osr_setting->osr_mask |
 					HP206C_CMD_ADC_CVT_CHNL_PT;
 			ret = hp206c_conv_and_read(indio_dev,
 					conv_cmd,
 					HP206C_CMD_READ_P,
 					osr_setting->pres_conv_time_us);
 			if (ret >= 0) {
 				*val = ret;
 				ret = IIO_VAL_INT;
 			}
 			break;
 		default:
 			ret = -EINVAL;
 		}
 		break;

 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_TEMP:
 			*val = 0;
 			*val2 = 10000;
 			ret = IIO_VAL_INT_PLUS_MICRO;
 			break;

 		case IIO_PRESSURE:
 			*val = 0;
 			*val2 = 1000;
 			ret = IIO_VAL_INT_PLUS_MICRO;
 			break;
 		default:
 			ret = -EINVAL;
 		}
 		break;

 	default:
 		ret = -EINVAL;
 	}

 	mutex_unlock(&data->mutex);
 	return ret;
 }

 static int hp206c_write_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int val, int val2, long mask)
 {
 	int ret = 0;
 	struct hp206c_data *data = iio_priv(indio_dev);

 	if (mask != IIO_CHAN_INFO_OVERSAMPLING_RATIO)
 		return -EINVAL;
 	mutex_lock(&data->mutex);
 	switch (chan->type) {
 	case IIO_TEMP:
 		data->temp_osr_index = find_closest_descending(val,
 			hp206c_osr_rates, ARRAY_SIZE(hp206c_osr_rates));
 		break;
 	case IIO_PRESSURE:
 		data->pres_osr_index = find_closest_descending(val,
 			hp206c_osr_rates, ARRAY_SIZE(hp206c_osr_rates));
 		break;
 	default:
 		ret = -EINVAL;
 	}
 	mutex_unlock(&data->mutex);
 	return ret;
 }

 static const struct iio_chan_spec hp206c_channels[] = {
 	{
 		.type = IIO_TEMP,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				      BIT(IIO_CHAN_INFO_SCALE) |
 				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
 	},
 	{
 		.type = IIO_PRESSURE,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				      BIT(IIO_CHAN_INFO_SCALE) |
 				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
 	}
 };

 static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(hp206c_osr_rates_str);

 static struct attribute *hp206c_attributes[] = {
 	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group hp206c_attribute_group = {
 	.attrs = hp206c_attributes,
 };

 static const struct iio_info hp206c_info = {
 	.attrs = &hp206c_attribute_group,
 	.read_raw = hp206c_read_raw,
 	.write_raw = hp206c_write_raw,
 };

 static int hp206c_probe(struct i2c_client *client)
 {
 	const struct i2c_device_id *id = i2c_client_get_device_id(client);
 	struct iio_dev *indio_dev;
 	struct hp206c_data *data;
 	int ret;

 	if (!i2c_check_functionality(client->adapter,
 				     I2C_FUNC_SMBUS_BYTE |
 				     I2C_FUNC_SMBUS_BYTE_DATA |
 				     I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
 		dev_err(&client->dev, "Adapter does not support "
 				"all required i2c functionality\n");
 		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->mutex);

 	indio_dev->info = &hp206c_info;
 	indio_dev->name = id->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = hp206c_channels;
 	indio_dev->num_channels = ARRAY_SIZE(hp206c_channels);

 	i2c_set_clientdata(client, indio_dev);

 	/* Do a soft reset on probe */
 	ret = hp206c_soft_reset(indio_dev);
 	if (ret) {
 		dev_err(&client->dev, "Failed to reset on startup: %d\n", ret);
 		return -ENODEV;
 	}

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

 static const struct i2c_device_id hp206c_id[] = {
 	{"hp206c"},
 	{}
 };
 MODULE_DEVICE_TABLE(i2c, hp206c_id);

 static const struct acpi_device_id hp206c_acpi_match[] = {
 	{"HOP206C", 0},
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, hp206c_acpi_match);

 static struct i2c_driver hp206c_driver = {
 	.probe = hp206c_probe,
 	.id_table = hp206c_id,
 	.driver = {
 		.name = "hp206c",
 		.acpi_match_table = hp206c_acpi_match,
 	},
 };

 module_i2c_driver(hp206c_driver);

 MODULE_DESCRIPTION("HOPERF HP206C precision barometer and altimeter sensor");
 MODULE_AUTHOR("Leonard Crestez <leonard.crestez@intel.com>");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* hp206c.c - HOPERF HP206C precision barometer and altimeter sensor
	*
	* Copyright (c) 2016, Intel Corporation.
	*
	* (7-bit I2C slave address 0x76)
	*
	* Datasheet:
	* http://www.hoperf.com/upload/sensor/HP206C_DataSheet_EN_V2.0.pdf
	*/

	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/i2c.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/delay.h>
	#include <linux/util_macros.h>

	#include <linux/unaligned.h>

	/* I2C commands: */
	#define HP206C_CMD_SOFT_RST 0x06

	#define HP206C_CMD_ADC_CVT 0x40

	#define HP206C_CMD_ADC_CVT_OSR_4096 0x00
	#define HP206C_CMD_ADC_CVT_OSR_2048 0x04
	#define HP206C_CMD_ADC_CVT_OSR_1024 0x08
	#define HP206C_CMD_ADC_CVT_OSR_512 0x0c
	#define HP206C_CMD_ADC_CVT_OSR_256 0x10
	#define HP206C_CMD_ADC_CVT_OSR_128 0x14

	#define HP206C_CMD_ADC_CVT_CHNL_PT 0x00
	#define HP206C_CMD_ADC_CVT_CHNL_T 0x02

	#define HP206C_CMD_READ_P 0x30
	#define HP206C_CMD_READ_T 0x32

	#define HP206C_CMD_READ_REG 0x80
	#define HP206C_CMD_WRITE_REG 0xc0

	#define HP206C_REG_INT_EN 0x0b
	#define HP206C_REG_INT_CFG 0x0c

	#define HP206C_REG_INT_SRC 0x0d
	#define HP206C_FLAG_DEV_RDY 0x40

	#define HP206C_REG_PARA 0x0f
	#define HP206C_FLAG_CMPS_EN 0x80

	/* Maximum spin for DEV_RDY */
	#define HP206C_MAX_DEV_RDY_WAIT_COUNT 20
	#define HP206C_DEV_RDY_WAIT_US 20000

	struct hp206c_data {
	struct mutex mutex;
	struct i2c_client *client;
	int temp_osr_index;
	int pres_osr_index;
	};

	struct hp206c_osr_setting {
	u8 osr_mask;
	unsigned int temp_conv_time_us;
	unsigned int pres_conv_time_us;
	};

	/* Data from Table 5 in datasheet. */
	static const struct hp206c_osr_setting hp206c_osr_settings[] = {
	{ HP206C_CMD_ADC_CVT_OSR_4096, 65600, 131100 },
	{ HP206C_CMD_ADC_CVT_OSR_2048, 32800, 65600 },
	{ HP206C_CMD_ADC_CVT_OSR_1024, 16400, 32800 },
	{ HP206C_CMD_ADC_CVT_OSR_512, 8200, 16400 },
	{ HP206C_CMD_ADC_CVT_OSR_256, 4100, 8200 },
	{ HP206C_CMD_ADC_CVT_OSR_128, 2100, 4100 },
	};
	static const int hp206c_osr_rates[] = { 4096, 2048, 1024, 512, 256, 128 };
	static const char hp206c_osr_rates_str[] = "4096 2048 1024 512 256 128";

	static inline int hp206c_read_reg(struct i2c_client *client, u8 reg)
	{
	return i2c_smbus_read_byte_data(client, HP206C_CMD_READ_REG \| reg);
	}

	static inline int hp206c_write_reg(struct i2c_client *client, u8 reg, u8 val)
	{
	return i2c_smbus_write_byte_data(client,
	HP206C_CMD_WRITE_REG \| reg, val);
	}

	static int hp206c_read_20bit(struct i2c_client *client, u8 cmd)
	{
	int ret;
	u8 values[3];

	ret = i2c_smbus_read_i2c_block_data(client, cmd, sizeof(values), values);
	if (ret < 0)
	return ret;
	if (ret != sizeof(values))
	return -EIO;
	return get_unaligned_be24(&values[0]) & GENMASK(19, 0);
	}

	/* Spin for max 160ms until DEV_RDY is 1, or return error. */
	static int hp206c_wait_dev_rdy(struct iio_dev *indio_dev)
	{
	int ret;
	int count = 0;
	struct hp206c_data *data = iio_priv(indio_dev);
	struct i2c_client *client = data->client;

	while (++count <= HP206C_MAX_DEV_RDY_WAIT_COUNT) {
	ret = hp206c_read_reg(client, HP206C_REG_INT_SRC);
	if (ret < 0) {
	dev_err(&indio_dev->dev, "Failed READ_REG INT_SRC: %d\n", ret);
	return ret;
	}
	if (ret & HP206C_FLAG_DEV_RDY)
	return 0;
	usleep_range(HP206C_DEV_RDY_WAIT_US, HP206C_DEV_RDY_WAIT_US * 3 / 2);
	}
	return -ETIMEDOUT;
	}

	static int hp206c_set_compensation(struct i2c_client *client, bool enabled)
	{
	int val;

	val = hp206c_read_reg(client, HP206C_REG_PARA);
	if (val < 0)
	return val;
	if (enabled)
	val \|= HP206C_FLAG_CMPS_EN;
	else
	val &= ~HP206C_FLAG_CMPS_EN;

	return hp206c_write_reg(client, HP206C_REG_PARA, val);
	}

	/* Do a soft reset */
	static int hp206c_soft_reset(struct iio_dev *indio_dev)
	{
	int ret;
	struct hp206c_data *data = iio_priv(indio_dev);
	struct i2c_client *client = data->client;

	ret = i2c_smbus_write_byte(client, HP206C_CMD_SOFT_RST);
	if (ret) {
	dev_err(&client->dev, "Failed to reset device: %d\n", ret);
	return ret;
	}

	usleep_range(400, 600);

	ret = hp206c_wait_dev_rdy(indio_dev);
	if (ret) {
	dev_err(&client->dev, "Device not ready after soft reset: %d\n", ret);
	return ret;
	}

	ret = hp206c_set_compensation(client, true);
	if (ret)
	dev_err(&client->dev, "Failed to enable compensation: %d\n", ret);
	return ret;
	}

	static int hp206c_conv_and_read(struct iio_dev *indio_dev,
	u8 conv_cmd, u8 read_cmd,
	unsigned int sleep_us)
	{
	int ret;
	struct hp206c_data *data = iio_priv(indio_dev);
	struct i2c_client *client = data->client;

	ret = hp206c_wait_dev_rdy(indio_dev);
	if (ret < 0) {
	dev_err(&indio_dev->dev, "Device not ready: %d\n", ret);
	return ret;
	}

	ret = i2c_smbus_write_byte(client, conv_cmd);
	if (ret < 0) {
	dev_err(&indio_dev->dev, "Failed convert: %d\n", ret);
	return ret;
	}

	usleep_range(sleep_us, sleep_us * 3 / 2);

	ret = hp206c_wait_dev_rdy(indio_dev);
	if (ret < 0) {
	dev_err(&indio_dev->dev, "Device not ready: %d\n", ret);
	return ret;
	}

	ret = hp206c_read_20bit(client, read_cmd);
	if (ret < 0)
	dev_err(&indio_dev->dev, "Failed read: %d\n", ret);

	return ret;
	}

	static int hp206c_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const chan, int val,
	int *val2, long mask)
	{
	int ret;
	struct hp206c_data *data = iio_priv(indio_dev);
	const struct hp206c_osr_setting *osr_setting;
	u8 conv_cmd;

	mutex_lock(&data->mutex);

	switch (mask) {
	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
	switch (chan->type) {
	case IIO_TEMP:
	*val = hp206c_osr_rates[data->temp_osr_index];
	ret = IIO_VAL_INT;
	break;

	case IIO_PRESSURE:
	*val = hp206c_osr_rates[data->pres_osr_index];
	ret = IIO_VAL_INT;
	break;
	default:
	ret = -EINVAL;
	}
	break;

	case IIO_CHAN_INFO_RAW:
	switch (chan->type) {
	case IIO_TEMP:
	osr_setting = &hp206c_osr_settings[data->temp_osr_index];
	conv_cmd = HP206C_CMD_ADC_CVT \|
	osr_setting->osr_mask \|
	HP206C_CMD_ADC_CVT_CHNL_T;
	ret = hp206c_conv_and_read(indio_dev,
	conv_cmd,
	HP206C_CMD_READ_T,
	osr_setting->temp_conv_time_us);
	if (ret >= 0) {
	/* 20 significant bits are provided.
	* Extend sign over the rest.
	*/
	*val = sign_extend32(ret, 19);
	ret = IIO_VAL_INT;
	}
	break;

	case IIO_PRESSURE:
	osr_setting = &hp206c_osr_settings[data->pres_osr_index];
	conv_cmd = HP206C_CMD_ADC_CVT \|
	osr_setting->osr_mask \|
	HP206C_CMD_ADC_CVT_CHNL_PT;
	ret = hp206c_conv_and_read(indio_dev,
	conv_cmd,
	HP206C_CMD_READ_P,
	osr_setting->pres_conv_time_us);
	if (ret >= 0) {
	*val = ret;
	ret = IIO_VAL_INT;
	}
	break;
	default:
	ret = -EINVAL;
	}
	break;

	case IIO_CHAN_INFO_SCALE:
	switch (chan->type) {
	case IIO_TEMP:
	*val = 0;
	*val2 = 10000;
	ret = IIO_VAL_INT_PLUS_MICRO;
	break;

	case IIO_PRESSURE:
	*val = 0;
	*val2 = 1000;
	ret = IIO_VAL_INT_PLUS_MICRO;
	break;
	default:
	ret = -EINVAL;
	}
	break;

	default:
	ret = -EINVAL;
	}

	mutex_unlock(&data->mutex);
	return ret;
	}

	static int hp206c_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	int ret = 0;
	struct hp206c_data *data = iio_priv(indio_dev);

	if (mask != IIO_CHAN_INFO_OVERSAMPLING_RATIO)
	return -EINVAL;
	mutex_lock(&data->mutex);
	switch (chan->type) {
	case IIO_TEMP:
	data->temp_osr_index = find_closest_descending(val,
	hp206c_osr_rates, ARRAY_SIZE(hp206c_osr_rates));
	break;
	case IIO_PRESSURE:
	data->pres_osr_index = find_closest_descending(val,
	hp206c_osr_rates, ARRAY_SIZE(hp206c_osr_rates));
	break;
	default:
	ret = -EINVAL;
	}
	mutex_unlock(&data->mutex);
	return ret;
	}

	static const struct iio_chan_spec hp206c_channels[] = {
	{
	.type = IIO_TEMP,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
	BIT(IIO_CHAN_INFO_SCALE) \|
	BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
	},
	{
	.type = IIO_PRESSURE,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
	BIT(IIO_CHAN_INFO_SCALE) \|
	BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
	}
	};

	static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(hp206c_osr_rates_str);

	static struct attribute *hp206c_attributes[] = {
	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group hp206c_attribute_group = {
	.attrs = hp206c_attributes,
	};

	static const struct iio_info hp206c_info = {
	.attrs = &hp206c_attribute_group,
	.read_raw = hp206c_read_raw,
	.write_raw = hp206c_write_raw,
	};

	static int hp206c_probe(struct i2c_client *client)
	{
	const struct i2c_device_id *id = i2c_client_get_device_id(client);
	struct iio_dev *indio_dev;
	struct hp206c_data *data;
	int ret;

	if (!i2c_check_functionality(client->adapter,
	I2C_FUNC_SMBUS_BYTE \|
	I2C_FUNC_SMBUS_BYTE_DATA \|
	I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
	dev_err(&client->dev, "Adapter does not support "
	"all required i2c functionality\n");
	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->mutex);

	indio_dev->info = &hp206c_info;
	indio_dev->name = id->name;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = hp206c_channels;
	indio_dev->num_channels = ARRAY_SIZE(hp206c_channels);

	i2c_set_clientdata(client, indio_dev);

	/* Do a soft reset on probe */
	ret = hp206c_soft_reset(indio_dev);
	if (ret) {
	dev_err(&client->dev, "Failed to reset on startup: %d\n", ret);
	return -ENODEV;
	}

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

	static const struct i2c_device_id hp206c_id[] = {
	{"hp206c"},
	{}
	};
	MODULE_DEVICE_TABLE(i2c, hp206c_id);

	static const struct acpi_device_id hp206c_acpi_match[] = {
	{"HOP206C", 0},
	{ },
	};
	MODULE_DEVICE_TABLE(acpi, hp206c_acpi_match);

	static struct i2c_driver hp206c_driver = {
	.probe = hp206c_probe,
	.id_table = hp206c_id,
	.driver = {
	.name = "hp206c",
	.acpi_match_table = hp206c_acpi_match,
	},
	};

	module_i2c_driver(hp206c_driver);

	MODULE_DESCRIPTION("HOPERF HP206C precision barometer and altimeter sensor");
	MODULE_AUTHOR("Leonard Crestez <leonard.crestez@intel.com>");
	MODULE_LICENSE("GPL v2");