drivers/iio/pressure/dps310.c - linux - Git at Google

 /*
  * Copyright 2017 IBM Corporation
  *
  * Joel Stanley <joel@jms.id.au>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version
  * 2 of the License, or (at your option) any later version.
  *
  * The DPS310 is a barometric pressure and temperature sensor.
  * Currently only reading a single temperature is supported by
  * this driver.
  *
  * https://www.infineon.com/dgdl/?fileId=5546d462576f34750157750826c42242
  *
  * Temperature calculation:
  *   c0 * 0.5 + c1 * T_raw / kT °C
  *
  * TODO:
  *  - Pressure sensor readings
  *  - Optionally support the FIFO
  */

 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/regmap.h>

 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>

 #define DPS310_PRS_B0		0x00
 #define DPS310_PRS_B1		0x01
 #define DPS310_PRS_B2		0x02
 #define DPS310_TMP_B0		0x03
 #define DPS310_TMP_B1		0x04
 #define DPS310_TMP_B2		0x05
 #define DPS310_PRS_CFG		0x06
 #define DPS310_TMP_CFG		0x07
 #define  DPS310_TMP_RATE_BITS	GENMASK(6, 4)
 #define  DPS310_TMP_PRC_BITS	GENMASK(3, 0)
 #define  DPS310_TMP_EXT		BIT(7)
 #define DPS310_MEAS_CFG		0x08
 #define  DPS310_MEAS_CTRL_BITS	GENMASK(2, 0)
 #define   DPS310_PRESSURE_EN	BIT(0)
 #define   DPS310_TEMP_EN	BIT(1)
 #define   DPS310_BACKGROUND	BIT(2)
 #define  DPS310_PRS_RDY		BIT(4)
 #define  DPS310_TMP_RDY		BIT(5)
 #define  DPS310_SENSOR_RDY	BIT(6)
 #define  DPS310_COEF_RDY	BIT(7)
 #define DPS310_CFG_REG		0x09
 #define  DPS310_INT_HL		BIT(7)
 #define  DPS310_TMP_SHIFT_EN	BIT(3)
 #define  DPS310_PRS_SHIFT_EN	BIT(4)
 #define  DPS310_FIFO_EN		BIT(5)
 #define  DPS310_SPI_EN		BIT(6)
 #define DPS310_RESET		0x0c
 #define  DPS310_RESET_MAGIC	(BIT(0) | BIT(3))
 #define DPS310_COEF_BASE	0x10

 #define DPS310_PRS_BASE		DPS310_PRS_B0
 #define DPS310_TMP_BASE		DPS310_TMP_B0

 #define DPS310_TMP_RATE(_n)	ilog2(_n)
 #define DPS310_TMP_PRC(_n)	ilog2(_n)

 #define MCELSIUS_PER_CELSIUS	1000

 const int scale_factor[] = {
 	 524288,
 	1572864,
 	3670016,
 	7864320,
 	 253952,
 	 516096,
 	1040384,
 	2088960,
 };

 struct dps310_data {
 	struct i2c_client *client;
 	struct regmap *regmap;

 	s32 c0, c1;
 	s32 temp_raw;
 };

 static const struct iio_chan_spec dps310_channels[] = {
 	{
 		.type = IIO_TEMP,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_OFFSET) |
 			BIT(IIO_CHAN_INFO_SCALE) |
 			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
 			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
 			BIT(IIO_CHAN_INFO_RAW),
 	},
 };

 /* To be called after checking the TMP_RDY bit in MEAS_CFG */
 static int dps310_get_temp_coef(struct dps310_data *data)
 {
 	struct regmap *regmap = data->regmap;
 	uint8_t coef[3] = {0};
 	int r;
 	u32 c0, c1;

 	/*
 	 * Read temperature calibration coefficients c0 and c1 from the
 	 * COEF register. The numbers are 12-bit 2's compliment numbers
 	 */
 	r = regmap_bulk_read(regmap, DPS310_COEF_BASE, coef, 3);
 	if (r < 0)
 		return r;

 	c0 = (coef[0] << 4) | (coef[1] >> 4);
 	data->c0 = sign_extend32(c0, 11);

 	c1 = ((coef[1] & GENMASK(3, 0)) << 8) | coef[2];
 	data->c1 = sign_extend32(c1, 11);

 	return 0;
 }

 static int dps310_get_temp_precision(struct dps310_data *data)
 {
 	int val, r;

 	r = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
 	if (r < 0)
 		return r;

 	/*
 	 * Scale factor is bottom 4 bits of the register, but 1111 is
 	 * reserved so just grab bottom three
 	 */
 	return BIT(val & GENMASK(2, 0));
 }

 static int dps310_set_temp_precision(struct dps310_data *data, int val)
 {
 	int ret;
 	u8 shift_en;

 	if (val < 0 || val > 128)
 		return -EINVAL;

 	shift_en = val >= 16 ? DPS310_TMP_SHIFT_EN : 0;
 	ret = regmap_write_bits(data->regmap, DPS310_CFG_REG,
 			DPS310_TMP_SHIFT_EN,
 			shift_en);
 	if (ret)
 		return ret;

 	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
 			DPS310_TMP_PRC_BITS, DPS310_TMP_PRC(val));
 }

 static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
 {
 	uint8_t val;

 	if (freq < 0 || freq > 128)
 		return -EINVAL;

 	val = DPS310_TMP_RATE(freq) << 4;

 	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
 			DPS310_TMP_RATE_BITS, val);
 }

 static int dps310_get_temp_samp_freq(struct dps310_data *data)
 {
 	int val, r;

 	r = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
 	if (r < 0)
 		return r;

 	return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
 }

 static int dps310_get_temp_k(struct dps310_data *data)
 {
 	return scale_factor[DPS310_TMP_PRC(dps310_get_temp_precision(data))];
 }

 static int dps310_read_temp(struct dps310_data *data)
 {
 	struct device *dev = &data->client->dev;
 	struct regmap *regmap = data->regmap;
 	uint8_t val[3] = {0};
 	int r, ready;
 	int T_raw;

 	r = regmap_read(regmap, DPS310_MEAS_CFG, &ready);
 	if (r < 0)
 		return r;
 	if (!(ready & DPS310_TMP_RDY)) {
 		dev_dbg(dev, "temperature not ready\n");
 		return -EAGAIN;
 	}

 	r = regmap_bulk_read(regmap, DPS310_TMP_BASE, val, 3);
 	if (r < 0)
 		return r;

 	T_raw = (val[0] << 16) | (val[1] << 8) | val[2];
 	data->temp_raw = sign_extend32(T_raw, 23);

 	return 0;
 }

 static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case DPS310_PRS_CFG:
 	case DPS310_TMP_CFG:
 	case DPS310_MEAS_CFG:
 	case DPS310_CFG_REG:
 	case DPS310_RESET:
 	case 0x0e:
 	case 0x0f:
 	case 0x62:
 		return true;
 	default:
 		return false;
 	}
 }

 static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case DPS310_PRS_B0:
 	case DPS310_PRS_B1:
 	case DPS310_PRS_B2:
 	case DPS310_TMP_B0:
 	case DPS310_TMP_B1:
 	case DPS310_TMP_B2:
 	case DPS310_MEAS_CFG:
 	case 0x32:
 		return true;
 	default:
 		return false;
 	}
 }

 static int dps310_write_raw(struct iio_dev *iio,
 			    struct iio_chan_spec const *chan, int val,
 			    int val2, long mask)
 {
 	struct dps310_data *data = iio_priv(iio);

 	if (chan->type != IIO_TEMP)
 		return -EINVAL;

 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		return dps310_set_temp_samp_freq(data, val);
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
 		return dps310_set_temp_precision(data, val);
 	default:
 		return -EINVAL;
 	}

 	return -EINVAL;
 }

 static int dps310_read_raw(struct iio_dev *iio,
 			   struct iio_chan_spec const *chan,
 			   int *val, int *val2, long mask)
 {
 	struct dps310_data *data = iio_priv(iio);
 	int ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*val = dps310_get_temp_samp_freq(data);
 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_RAW:
 		ret = dps310_read_temp(data);
 		if (ret)
 			return ret;

 		*val = data->temp_raw * data->c1;
 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_OFFSET:
 		*val = (data->c0 >> 1) * dps310_get_temp_k(data);
 		return IIO_VAL_INT;

 	case IIO_CHAN_INFO_SCALE:
 		*val = 1000; /* milliCelsius per Celsius */
 		*val2 = dps310_get_temp_k(data);
 		return IIO_VAL_FRACTIONAL;

 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
 		*val = dps310_get_temp_precision(data);
 		return IIO_VAL_INT;

 	default:
 		return -EINVAL;
 	}

 	return -EINVAL;
 }

 static const struct regmap_config dps310_regmap_config = {
 	.reg_bits = 8,
 	.val_bits = 8,
 	.writeable_reg = dps310_is_writeable_reg,
 	.volatile_reg = dps310_is_volatile_reg,
 	.cache_type = REGCACHE_RBTREE,
 	.max_register = 0x62,
 };

 static const struct iio_info dps310_info = {
 	.driver_module = THIS_MODULE,
 	.read_raw = dps310_read_raw,
 	.write_raw = dps310_write_raw,
 };

 /*
  * Some verions of chip will read temperatures in the ~60C range when
  * its acutally ~20C. This is the manufacturer recommended workaround
  * to correct the issue.
  */
 static int dps310_temp_workaround(struct dps310_data *data)
 {
 	int r, reg;

 	r = regmap_read(data->regmap, 0x32, &reg);
 	if (r < 0)
 		return r;

 	/* If bit 1 is set then the device is okay, and the workaround does not
 	 * need to be applied */
 	if (reg & BIT(1))
 		return 0;

 	r = regmap_write(data->regmap, 0x0e, 0xA5);
 	if (r < 0)
 		return r;

 	r = regmap_write(data->regmap, 0x0f, 0x96);
 	if (r < 0)
 		return r;

 	r = regmap_write(data->regmap, 0x62, 0x02);
 	if (r < 0)
 		return r;

 	r = regmap_write(data->regmap, 0x0e, 0x00);
 	if (r < 0)
 		return r;

 	r = regmap_write(data->regmap, 0x0f, 0x00);

 	return r;
 }

 static int dps310_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct dps310_data *data;
 	struct iio_dev *iio;
 	int r, ready;

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

 	data = iio_priv(iio);
 	data->client = client;

 	iio->dev.parent = &client->dev;
 	iio->name = id->name;
 	iio->channels = dps310_channels;
 	iio->num_channels = ARRAY_SIZE(dps310_channels);
 	iio->info = &dps310_info;
 	iio->modes = INDIO_DIRECT_MODE;

 	data->regmap = devm_regmap_init_i2c(client, &dps310_regmap_config);
 	if (IS_ERR(data->regmap))
 		return PTR_ERR(data->regmap);

 	/*
 	 * Set up external (MEMS) temperature sensor in single sample, one
 	 * measurement per second mode
 	 */
 	r = regmap_write(data->regmap, DPS310_TMP_CFG,
 			DPS310_TMP_EXT | DPS310_TMP_RATE(1) | DPS310_TMP_PRC(1));
 	if (r < 0)
 		return r;

 	/* Temp shift is disabled when PRC <= 8 */
 	r = regmap_write_bits(data->regmap, DPS310_CFG_REG,
 			DPS310_TMP_SHIFT_EN, 0);
 	if (r < 0)
 		return r;

 	/* Turn on temperature measurement in the background */
 	r = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
 			DPS310_MEAS_CTRL_BITS,
 			DPS310_TEMP_EN | DPS310_BACKGROUND);
 	if (r < 0)
 		return r;

 	/*
 	 * Calibration coefficients required for reporting temperature.
 	 * They are available 40ms after the device has started
 	 */
 	r = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
 			ready & DPS310_COEF_RDY,
 			10 * 1000,
 			40 * 1000);
 	if (r < 0)
 		return r;

 	r = dps310_get_temp_coef(data);
 	if (r < 0)
 		return r;

 	r = dps310_temp_workaround(data);
 	if (r < 0)
 		return r;

 	r = devm_iio_device_register(&client->dev, iio);
 	if (r)
 		return r;

 	i2c_set_clientdata(client, iio);

 	dev_info(&client->dev, "%s: sensor '%s'\n", dev_name(&iio->dev),
 			client->name);

 	return 0;
 }

 static int dps310_remove(struct i2c_client *client)
 {
 	struct dps310_data *data = i2c_get_clientdata(client);

 	return regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
 }

 static const struct i2c_device_id dps310_id[] = {
 	{ "dps310", 0 },
 	{}
 };
 MODULE_DEVICE_TABLE(i2c, dps310_id);

 static const unsigned short normal_i2c[] = {
 	0x77, 0x76, I2C_CLIENT_END
 };

 static struct i2c_driver dps310_driver = {
 	.driver = {
 		.name = "dps310",
 	},
 	.probe = dps310_probe,
 	.remove = dps310_remove,
 	.address_list = normal_i2c,
 	.id_table = dps310_id,
 };
 module_i2c_driver(dps310_driver);

 MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
 MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
 MODULE_LICENSE("GPL");
	/*
	* Copyright 2017 IBM Corporation
	*
	* Joel Stanley <joel@jms.id.au>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version
	* 2 of the License, or (at your option) any later version.
	*
	* The DPS310 is a barometric pressure and temperature sensor.
	* Currently only reading a single temperature is supported by
	* this driver.
	*
	* https://www.infineon.com/dgdl/?fileId=5546d462576f34750157750826c42242
	*
	* Temperature calculation:
	* c0 * 0.5 + c1 * T_raw / kT °C
	*
	* TODO:
	* - Pressure sensor readings
	* - Optionally support the FIFO
	*/

	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/regmap.h>

	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>

	#define DPS310_PRS_B0 0x00
	#define DPS310_PRS_B1 0x01
	#define DPS310_PRS_B2 0x02
	#define DPS310_TMP_B0 0x03
	#define DPS310_TMP_B1 0x04
	#define DPS310_TMP_B2 0x05
	#define DPS310_PRS_CFG 0x06
	#define DPS310_TMP_CFG 0x07
	#define DPS310_TMP_RATE_BITS GENMASK(6, 4)
	#define DPS310_TMP_PRC_BITS GENMASK(3, 0)
	#define DPS310_TMP_EXT BIT(7)
	#define DPS310_MEAS_CFG 0x08
	#define DPS310_MEAS_CTRL_BITS GENMASK(2, 0)
	#define DPS310_PRESSURE_EN BIT(0)
	#define DPS310_TEMP_EN BIT(1)
	#define DPS310_BACKGROUND BIT(2)
	#define DPS310_PRS_RDY BIT(4)
	#define DPS310_TMP_RDY BIT(5)
	#define DPS310_SENSOR_RDY BIT(6)
	#define DPS310_COEF_RDY BIT(7)
	#define DPS310_CFG_REG 0x09
	#define DPS310_INT_HL BIT(7)
	#define DPS310_TMP_SHIFT_EN BIT(3)
	#define DPS310_PRS_SHIFT_EN BIT(4)
	#define DPS310_FIFO_EN BIT(5)
	#define DPS310_SPI_EN BIT(6)
	#define DPS310_RESET 0x0c
	#define DPS310_RESET_MAGIC (BIT(0) \| BIT(3))
	#define DPS310_COEF_BASE 0x10

	#define DPS310_PRS_BASE DPS310_PRS_B0
	#define DPS310_TMP_BASE DPS310_TMP_B0

	#define DPS310_TMP_RATE(_n) ilog2(_n)
	#define DPS310_TMP_PRC(_n) ilog2(_n)

	#define MCELSIUS_PER_CELSIUS 1000

	const int scale_factor[] = {
	524288,
	1572864,
	3670016,
	7864320,
	253952,
	516096,
	1040384,
	2088960,
	};

	struct dps310_data {
	struct i2c_client *client;
	struct regmap *regmap;

	s32 c0, c1;
	s32 temp_raw;
	};

	static const struct iio_chan_spec dps310_channels[] = {
	{
	.type = IIO_TEMP,
	.info_mask_separate = BIT(IIO_CHAN_INFO_OFFSET) \|
	BIT(IIO_CHAN_INFO_SCALE) \|
	BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) \|
	BIT(IIO_CHAN_INFO_SAMP_FREQ) \|
	BIT(IIO_CHAN_INFO_RAW),
	},
	};

	/* To be called after checking the TMP_RDY bit in MEAS_CFG */
	static int dps310_get_temp_coef(struct dps310_data *data)
	{
	struct regmap *regmap = data->regmap;
	uint8_t coef[3] = {0};
	int r;
	u32 c0, c1;

	/*
	* Read temperature calibration coefficients c0 and c1 from the
	* COEF register. The numbers are 12-bit 2's compliment numbers
	*/
	r = regmap_bulk_read(regmap, DPS310_COEF_BASE, coef, 3);
	if (r < 0)
	return r;

	c0 = (coef[0] << 4) \| (coef[1] >> 4);
	data->c0 = sign_extend32(c0, 11);

	c1 = ((coef[1] & GENMASK(3, 0)) << 8) \| coef[2];
	data->c1 = sign_extend32(c1, 11);

	return 0;
	}

	static int dps310_get_temp_precision(struct dps310_data *data)
	{
	int val, r;

	r = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
	if (r < 0)
	return r;

	/*
	* Scale factor is bottom 4 bits of the register, but 1111 is
	* reserved so just grab bottom three
	*/
	return BIT(val & GENMASK(2, 0));
	}

	static int dps310_set_temp_precision(struct dps310_data *data, int val)
	{
	int ret;
	u8 shift_en;

	if (val < 0 \|\| val > 128)
	return -EINVAL;

	shift_en = val >= 16 ? DPS310_TMP_SHIFT_EN : 0;
	ret = regmap_write_bits(data->regmap, DPS310_CFG_REG,
	DPS310_TMP_SHIFT_EN,
	shift_en);
	if (ret)
	return ret;

	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
	DPS310_TMP_PRC_BITS, DPS310_TMP_PRC(val));
	}

	static int dps310_set_temp_samp_freq(struct dps310_data *data, int freq)
	{
	uint8_t val;

	if (freq < 0 \|\| freq > 128)
	return -EINVAL;

	val = DPS310_TMP_RATE(freq) << 4;

	return regmap_update_bits(data->regmap, DPS310_TMP_CFG,
	DPS310_TMP_RATE_BITS, val);
	}

	static int dps310_get_temp_samp_freq(struct dps310_data *data)
	{
	int val, r;

	r = regmap_read(data->regmap, DPS310_TMP_CFG, &val);
	if (r < 0)
	return r;

	return BIT((val & DPS310_TMP_RATE_BITS) >> 4);
	}

	static int dps310_get_temp_k(struct dps310_data *data)
	{
	return scale_factor[DPS310_TMP_PRC(dps310_get_temp_precision(data))];
	}

	static int dps310_read_temp(struct dps310_data *data)
	{
	struct device *dev = &data->client->dev;
	struct regmap *regmap = data->regmap;
	uint8_t val[3] = {0};
	int r, ready;
	int T_raw;

	r = regmap_read(regmap, DPS310_MEAS_CFG, &ready);
	if (r < 0)
	return r;
	if (!(ready & DPS310_TMP_RDY)) {
	dev_dbg(dev, "temperature not ready\n");
	return -EAGAIN;
	}

	r = regmap_bulk_read(regmap, DPS310_TMP_BASE, val, 3);
	if (r < 0)
	return r;

	T_raw = (val[0] << 16) \| (val[1] << 8) \| val[2];
	data->temp_raw = sign_extend32(T_raw, 23);

	return 0;
	}

	static bool dps310_is_writeable_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case DPS310_PRS_CFG:
	case DPS310_TMP_CFG:
	case DPS310_MEAS_CFG:
	case DPS310_CFG_REG:
	case DPS310_RESET:
	case 0x0e:
	case 0x0f:
	case 0x62:
	return true;
	default:
	return false;
	}
	}

	static bool dps310_is_volatile_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case DPS310_PRS_B0:
	case DPS310_PRS_B1:
	case DPS310_PRS_B2:
	case DPS310_TMP_B0:
	case DPS310_TMP_B1:
	case DPS310_TMP_B2:
	case DPS310_MEAS_CFG:
	case 0x32:
	return true;
	default:
	return false;
	}
	}

	static int dps310_write_raw(struct iio_dev *iio,
	struct iio_chan_spec const *chan, int val,
	int val2, long mask)
	{
	struct dps310_data *data = iio_priv(iio);

	if (chan->type != IIO_TEMP)
	return -EINVAL;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
	return dps310_set_temp_samp_freq(data, val);
	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
	return dps310_set_temp_precision(data, val);
	default:
	return -EINVAL;
	}

	return -EINVAL;
	}

	static int dps310_read_raw(struct iio_dev *iio,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct dps310_data *data = iio_priv(iio);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
	*val = dps310_get_temp_samp_freq(data);
	return IIO_VAL_INT;

	case IIO_CHAN_INFO_RAW:
	ret = dps310_read_temp(data);
	if (ret)
	return ret;

	val = data->temp_raw data->c1;
	return IIO_VAL_INT;

	case IIO_CHAN_INFO_OFFSET:
	val = (data->c0 >> 1) dps310_get_temp_k(data);
	return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:
	val = 1000; / milliCelsius per Celsius */
	*val2 = dps310_get_temp_k(data);
	return IIO_VAL_FRACTIONAL;

	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
	*val = dps310_get_temp_precision(data);
	return IIO_VAL_INT;

	default:
	return -EINVAL;
	}

	return -EINVAL;
	}

	static const struct regmap_config dps310_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.writeable_reg = dps310_is_writeable_reg,
	.volatile_reg = dps310_is_volatile_reg,
	.cache_type = REGCACHE_RBTREE,
	.max_register = 0x62,
	};

	static const struct iio_info dps310_info = {
	.driver_module = THIS_MODULE,
	.read_raw = dps310_read_raw,
	.write_raw = dps310_write_raw,
	};

	/*
	* Some verions of chip will read temperatures in the ~60C range when
	* its acutally ~20C. This is the manufacturer recommended workaround
	* to correct the issue.
	*/
	static int dps310_temp_workaround(struct dps310_data *data)
	{
	int r, reg;

	r = regmap_read(data->regmap, 0x32, &reg);
	if (r < 0)
	return r;

	/* If bit 1 is set then the device is okay, and the workaround does not
	* need to be applied */
	if (reg & BIT(1))
	return 0;

	r = regmap_write(data->regmap, 0x0e, 0xA5);
	if (r < 0)
	return r;

	r = regmap_write(data->regmap, 0x0f, 0x96);
	if (r < 0)
	return r;

	r = regmap_write(data->regmap, 0x62, 0x02);
	if (r < 0)
	return r;

	r = regmap_write(data->regmap, 0x0e, 0x00);
	if (r < 0)
	return r;

	r = regmap_write(data->regmap, 0x0f, 0x00);

	return r;
	}

	static int dps310_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct dps310_data *data;
	struct iio_dev *iio;
	int r, ready;

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

	data = iio_priv(iio);
	data->client = client;

	iio->dev.parent = &client->dev;
	iio->name = id->name;
	iio->channels = dps310_channels;
	iio->num_channels = ARRAY_SIZE(dps310_channels);
	iio->info = &dps310_info;
	iio->modes = INDIO_DIRECT_MODE;

	data->regmap = devm_regmap_init_i2c(client, &dps310_regmap_config);
	if (IS_ERR(data->regmap))
	return PTR_ERR(data->regmap);

	/*
	* Set up external (MEMS) temperature sensor in single sample, one
	* measurement per second mode
	*/
	r = regmap_write(data->regmap, DPS310_TMP_CFG,
	DPS310_TMP_EXT \| DPS310_TMP_RATE(1) \| DPS310_TMP_PRC(1));
	if (r < 0)
	return r;

	/* Temp shift is disabled when PRC <= 8 */
	r = regmap_write_bits(data->regmap, DPS310_CFG_REG,
	DPS310_TMP_SHIFT_EN, 0);
	if (r < 0)
	return r;

	/* Turn on temperature measurement in the background */
	r = regmap_write_bits(data->regmap, DPS310_MEAS_CFG,
	DPS310_MEAS_CTRL_BITS,
	DPS310_TEMP_EN \| DPS310_BACKGROUND);
	if (r < 0)
	return r;

	/*
	* Calibration coefficients required for reporting temperature.
	* They are available 40ms after the device has started
	*/
	r = regmap_read_poll_timeout(data->regmap, DPS310_MEAS_CFG, ready,
	ready & DPS310_COEF_RDY,
	10 * 1000,
	40 * 1000);
	if (r < 0)
	return r;

	r = dps310_get_temp_coef(data);
	if (r < 0)
	return r;

	r = dps310_temp_workaround(data);
	if (r < 0)
	return r;

	r = devm_iio_device_register(&client->dev, iio);
	if (r)
	return r;

	i2c_set_clientdata(client, iio);

	dev_info(&client->dev, "%s: sensor '%s'\n", dev_name(&iio->dev),
	client->name);

	return 0;
	}

	static int dps310_remove(struct i2c_client *client)
	{
	struct dps310_data *data = i2c_get_clientdata(client);

	return regmap_write(data->regmap, DPS310_RESET, DPS310_RESET_MAGIC);
	}

	static const struct i2c_device_id dps310_id[] = {
	{ "dps310", 0 },
	{}
	};
	MODULE_DEVICE_TABLE(i2c, dps310_id);

	static const unsigned short normal_i2c[] = {
	0x77, 0x76, I2C_CLIENT_END
	};

	static struct i2c_driver dps310_driver = {
	.driver = {
	.name = "dps310",
	},
	.probe = dps310_probe,
	.remove = dps310_remove,
	.address_list = normal_i2c,
	.id_table = dps310_id,
	};
	module_i2c_driver(dps310_driver);

	MODULE_AUTHOR("Joel Stanley <joel@jms.id.au>");
	MODULE_DESCRIPTION("Infineon DPS310 pressure and temperature sensor");
	MODULE_LICENSE("GPL");