Re: [PATCH v4 1/7] Add meas-spec sensors common part

[Jonathan Cameron <jic23@kernel.org>]

On 01/10/15 15:13, Ludovic Tancerel wrote:
> Measurement specialties drivers common part.
> These functions are used by further drivers
> in the patchset: TSYS01, TSYS02D, HTU21, MS5637, MS8607
> 
> Signed-off-by: Ludovic Tancerel <ludovic.tancerel@maplehightech.com>
Thanks for your persistence on this!

Anyhow, applied to the togreg branch of iio.git. Initially pushed out
as testing for the autobuilders to play with it.

Thanks,

Jonathan
> ---
>  drivers/iio/common/Kconfig                     |   1 +
>  drivers/iio/common/Makefile                    |   1 +
>  drivers/iio/common/ms_sensors/Kconfig          |   6 +
>  drivers/iio/common/ms_sensors/Makefile         |   5 +
>  drivers/iio/common/ms_sensors/ms_sensors_i2c.c | 651 +++++++++++++++++++++++++
>  drivers/iio/common/ms_sensors/ms_sensors_i2c.h |  66 +++
>  6 files changed, 730 insertions(+)
>  create mode 100644 drivers/iio/common/ms_sensors/Kconfig
>  create mode 100644 drivers/iio/common/ms_sensors/Makefile
>  create mode 100644 drivers/iio/common/ms_sensors/ms_sensors_i2c.c
>  create mode 100644 drivers/iio/common/ms_sensors/ms_sensors_i2c.h
> 
> diff --git a/drivers/iio/common/Kconfig b/drivers/iio/common/Kconfig
> index 790f106..26a6026 100644
> --- a/drivers/iio/common/Kconfig
> +++ b/drivers/iio/common/Kconfig
> @@ -3,5 +3,6 @@
>  #
>  
>  source "drivers/iio/common/hid-sensors/Kconfig"
> +source "drivers/iio/common/ms_sensors/Kconfig"
>  source "drivers/iio/common/ssp_sensors/Kconfig"
>  source "drivers/iio/common/st_sensors/Kconfig"
> diff --git a/drivers/iio/common/Makefile b/drivers/iio/common/Makefile
> index b1e4d9c..585da6a 100644
> --- a/drivers/iio/common/Makefile
> +++ b/drivers/iio/common/Makefile
> @@ -8,5 +8,6 @@
>  
>  # When adding new entries keep the list in alphabetical order
>  obj-y += hid-sensors/
> +obj-y += ms_sensors/
>  obj-y += ssp_sensors/
>  obj-y += st_sensors/
> diff --git a/drivers/iio/common/ms_sensors/Kconfig b/drivers/iio/common/ms_sensors/Kconfig
> new file mode 100644
> index 0000000..b28a92b
> --- /dev/null
> +++ b/drivers/iio/common/ms_sensors/Kconfig
> @@ -0,0 +1,6 @@
> +#
> +# Measurements Specialties sensors common library
> +#
> +
> +config IIO_MS_SENSORS_I2C
> +        tristate
> diff --git a/drivers/iio/common/ms_sensors/Makefile b/drivers/iio/common/ms_sensors/Makefile
> new file mode 100644
> index 0000000..7846428
> --- /dev/null
> +++ b/drivers/iio/common/ms_sensors/Makefile
> @@ -0,0 +1,5 @@
> +#
> +# Makefile for the Measurement Specialties sensor common modules.
> +#
> +
> +obj-$(CONFIG_IIO_MS_SENSORS_I2C) += ms_sensors_i2c.o
> diff --git a/drivers/iio/common/ms_sensors/ms_sensors_i2c.c b/drivers/iio/common/ms_sensors/ms_sensors_i2c.c
> new file mode 100644
> index 0000000..056c4f3
> --- /dev/null
> +++ b/drivers/iio/common/ms_sensors/ms_sensors_i2c.c
> @@ -0,0 +1,651 @@
> +/*
> + * Measurements Specialties driver common i2c functions
> + *
> + * Copyright (c) 2015 Measurement-Specialties
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/iio/iio.h>
> +#include <linux/device.h>
> +#include <linux/delay.h>
> +
> +#include "ms_sensors_i2c.h"
> +
> +/* Conversion times in us */
> +static const u16 ms_sensors_ht_t_conversion_time[] = { 50000, 25000,
> +						       13000, 7000 };
> +static const u16 ms_sensors_ht_h_conversion_time[] = { 16000, 3000,
> +						       5000, 8000 };
> +static const u16 ms_sensors_tp_conversion_time[] = { 500, 1100, 2100,
> +						     4100, 8220, 16440 };
> +
> +#define MS_SENSORS_SERIAL_READ_MSB		0xFA0F
> +#define MS_SENSORS_SERIAL_READ_LSB		0xFCC9
> +#define MS_SENSORS_CONFIG_REG_WRITE		0xE6
> +#define MS_SENSORS_CONFIG_REG_READ		0xE7
> +#define MS_SENSORS_HT_T_CONVERSION_START	0xF3
> +#define MS_SENSORS_HT_H_CONVERSION_START	0xF5
> +
> +#define MS_SENSORS_TP_PROM_READ			0xA0
> +#define MS_SENSORS_TP_T_CONVERSION_START	0x50
> +#define MS_SENSORS_TP_P_CONVERSION_START	0x40
> +#define MS_SENSORS_TP_ADC_READ			0x00
> +
> +#define MS_SENSORS_NO_READ_CMD			0xFF
> +
> +/**
> + * ms_sensors_reset() - Reset function
> + * @cli:	pointer to device client
> + * @cmd:	reset cmd. Depends on device in use
> + * @delay:	usleep minimal delay after reset command is issued
> + *
> + * Generic I2C reset function for Measurement Specialties devices.
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +int ms_sensors_reset(void *cli, u8 cmd, unsigned int delay)
> +{
> +	int ret;
> +	struct i2c_client *client = cli;
> +
> +	ret = i2c_smbus_write_byte(client, cmd);
> +	if (ret) {
> +		dev_err(&client->dev, "Failed to reset device\n");
> +		return ret;
> +	}
> +	usleep_range(delay, delay + 1000);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(ms_sensors_reset);
> +
> +/**
> + * ms_sensors_read_prom_word() - PROM word read function
> + * @cli:	pointer to device client
> + * @cmd:	PROM read cmd. Depends on device and prom id
> + * @word:	pointer to word destination value
> + *
> + * Generic i2c prom word read function for Measurement Specialties devices.
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +int ms_sensors_read_prom_word(void *cli, int cmd, u16 *word)
> +{
> +	int ret;
> +	struct i2c_client *client = (struct i2c_client *)cli;
> +
> +	ret = i2c_smbus_read_word_swapped(client, cmd);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Failed to read prom word\n");
> +		return ret;
> +	}
> +	*word = ret;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(ms_sensors_read_prom_word);
> +
> +/**
> + * ms_sensors_convert_and_read() - ADC conversion & read function
> + * @cli:	pointer to device client
> + * @conv:	ADC conversion command. Depends on device in use
> + * @rd:		ADC read command. Depends on device in use
> + * @delay:	usleep minimal delay after conversion command is issued
> + * @adc:	pointer to ADC destination value
> + *
> + * Generic ADC conversion & read function for Measurement Specialties
> + * devices.
> + * The function will issue conversion command, sleep appopriate delay, and
> + * issue command to read ADC.
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +int ms_sensors_convert_and_read(void *cli, u8 conv, u8 rd,
> +				unsigned int delay, u32 *adc)
> +{
> +	int ret;
> +	u32 buf = 0;
> +	struct i2c_client *client = (struct i2c_client *)cli;
> +
> +	/* Trigger conversion */
> +	ret = i2c_smbus_write_byte(client, conv);
> +	if (ret)
> +		goto err;
> +	usleep_range(delay, delay + 1000);
> +
> +	/* Retrieve ADC value */
> +	if (rd != MS_SENSORS_NO_READ_CMD)
> +		ret = i2c_smbus_read_i2c_block_data(client, rd, 3, (u8 *)&buf);
> +	else
> +		ret = i2c_master_recv(client, (u8 *)&buf, 3);
> +	if (ret < 0)
> +		goto err;
> +
> +	dev_dbg(&client->dev, "ADC raw value : %x\n", be32_to_cpu(buf) >> 8);
> +	*adc = be32_to_cpu(buf) >> 8;
> +
> +	return 0;
> +err:
> +	dev_err(&client->dev, "Unable to make sensor adc conversion\n");
> +	return ret;
> +}
> +EXPORT_SYMBOL(ms_sensors_convert_and_read);
> +
> +/**
> + * ms_sensors_crc_valid() - CRC check function
> + * @value:	input and CRC compare value
> + *
> + * Cyclic Redundancy Check function used in TSYS02D, HTU21, MS8607.
> + * This function performs a x^8 + x^5 + x^4 + 1 polynomial CRC.
> + * The argument contains CRC value in LSB byte while the bytes 1 and 2
> + * are used for CRC computation.
> + *
> + * Return: 1 if CRC is valid, 0 otherwise.
> + */
> +static bool ms_sensors_crc_valid(u32 value)
> +{
> +	u32 polynom = 0x988000;	/* x^8 + x^5 + x^4 + 1 */
> +	u32 msb = 0x800000;
> +	u32 mask = 0xFF8000;
> +	u32 result = value & 0xFFFF00;
> +	u8 crc = value & 0xFF;
> +
> +	while (msb != 0x80) {
> +		if (result & msb)
> +			result = ((result ^ polynom) & mask)
> +				| (result & ~mask);
> +		msb >>= 1;
> +		mask >>= 1;
> +		polynom >>= 1;
> +	}
> +
> +	return result == crc;
> +}
> +
> +/**
> + * ms_sensors_read_serial() - Serial number read function
> + * @cli:	pointer to i2c client
> + * @sn:		pointer to 64-bits destination value
> + *
> + * Generic i2c serial number read function for Measurement Specialties devices.
> + * This function is used for TSYS02d, HTU21, MS8607 chipset.
> + * Refer to datasheet:
> + *	http://www.meas-spec.com/downloads/HTU2X_Serial_Number_Reading.pdf
> + *
> + * Sensor raw MSB serial number format is the following :
> + *	[ SNB3, CRC, SNB2, CRC, SNB1, CRC, SNB0, CRC]
> + * Sensor raw LSB serial number format is the following :
> + *	[ X, X, SNC1, SNC0, CRC, SNA1, SNA0, CRC]
> + * The resulting serial number is following :
> + *	[ SNA1, SNA0, SNB3, SNB2, SNB1, SNB0, SNC1, SNC0]
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +int ms_sensors_read_serial(struct i2c_client *client, u64 *sn)
> +{
> +	u8 i;
> +	u64 rcv_buf = 0;
> +	u16 send_buf;
> +	int ret;
> +
> +	struct i2c_msg msg[2] = {
> +		{
> +		 .addr = client->addr,
> +		 .flags = client->flags,
> +		 .len = 2,
> +		 .buf = (__u8 *)&send_buf,
> +		 },
> +		{
> +		 .addr = client->addr,
> +		 .flags = client->flags | I2C_M_RD,
> +		 .buf = (__u8 *)&rcv_buf,
> +		 },
> +	};
> +
> +	/* Read MSB part of serial number */
> +	send_buf = cpu_to_be16(MS_SENSORS_SERIAL_READ_MSB);
> +	msg[1].len = 8;
> +	ret = i2c_transfer(client->adapter, msg, 2);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Unable to read device serial number");
> +		return ret;
> +	}
> +
> +	rcv_buf = be64_to_cpu(rcv_buf);
> +	dev_dbg(&client->dev, "Serial MSB raw : %llx\n", rcv_buf);
> +
> +	for (i = 0; i < 64; i += 16) {
> +		if (!ms_sensors_crc_valid((rcv_buf >> i) & 0xFFFF))
> +			return -ENODEV;
> +	}
> +
> +	*sn = (((rcv_buf >> 32) & 0xFF000000) |
> +	       ((rcv_buf >> 24) & 0x00FF0000) |
> +	       ((rcv_buf >> 16) & 0x0000FF00) |
> +	       ((rcv_buf >> 8) & 0x000000FF)) << 16;
> +
> +	/* Read LSB part of serial number */
> +	send_buf = cpu_to_be16(MS_SENSORS_SERIAL_READ_LSB);
> +	msg[1].len = 6;
> +	rcv_buf = 0;
> +	ret = i2c_transfer(client->adapter, msg, 2);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Unable to read device serial number");
> +		return ret;
> +	}
> +
> +	rcv_buf = be64_to_cpu(rcv_buf) >> 16;
> +	dev_dbg(&client->dev, "Serial MSB raw : %llx\n", rcv_buf);
> +
> +	for (i = 0; i < 48; i += 24) {
> +		if (!ms_sensors_crc_valid((rcv_buf >> i) & 0xFFFFFF))
> +			return -ENODEV;
> +	}
> +
> +	*sn |= (rcv_buf & 0xFFFF00) << 40 | (rcv_buf >> 32);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(ms_sensors_read_serial);
> +
> +static int ms_sensors_read_config_reg(struct i2c_client *client,
> +				      u8 *config_reg)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte(client, MS_SENSORS_CONFIG_REG_READ);
> +	if (ret) {
> +		dev_err(&client->dev, "Unable to read config register");
> +		return ret;
> +	}
> +
> +	ret = i2c_master_recv(client, config_reg, 1);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "Unable to read config register");
> +		return ret;
> +	}
> +	dev_dbg(&client->dev, "Config register :%x\n", *config_reg);
> +
> +	return 0;
> +}
> +
> +/**
> + * ms_sensors_write_resolution() - Set resolution function
> + * @dev_data:	pointer to temperature/humidity device data
> + * @i:		resolution index to set
> + *
> + * This function will program the appropriate resolution based on the index
> + * provided when user space will set samp_freq channel.
> + * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +ssize_t ms_sensors_write_resolution(struct ms_ht_dev *dev_data,
> +				    u8 i)
> +{
> +	u8 config_reg;
> +	int ret;
> +
> +	ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
> +	if (ret)
> +		return ret;
> +
> +	config_reg &= 0x7E;
> +	config_reg |= ((i & 1) << 7) + ((i & 2) >> 1);
> +
> +	return i2c_smbus_write_byte_data(dev_data->client,
> +					 MS_SENSORS_CONFIG_REG_WRITE,
> +					 config_reg);
> +}
> +EXPORT_SYMBOL(ms_sensors_write_resolution);
> +
> +/**
> + * ms_sensors_show_battery_low() - Show device battery low indicator
> + * @dev_data:	pointer to temperature/humidity device data
> + * @buf:	pointer to char buffer to write result
> + *
> + * This function will read battery indicator value in the device and
> + * return 1 if the device voltage is below 2.25V.
> + * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
> + *
> + * Return: length of sprintf on success, negative errno otherwise.
> + */
> +ssize_t ms_sensors_show_battery_low(struct ms_ht_dev *dev_data,
> +				    char *buf)
> +{
> +	int ret;
> +	u8 config_reg;
> +
> +	mutex_lock(&dev_data->lock);
> +	ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
> +	mutex_unlock(&dev_data->lock);
> +	if (ret)
> +		return ret;
> +
> +	return sprintf(buf, "%d\n", (config_reg & 0x40) >> 6);
> +}
> +EXPORT_SYMBOL(ms_sensors_show_battery_low);
> +
> +/**
> + * ms_sensors_show_heater() - Show device heater
> + * @dev_data:	pointer to temperature/humidity device data
> + * @buf:	pointer to char buffer to write result
> + *
> + * This function will read heater enable value in the device and
> + * return 1 if the heater is enabled.
> + * This function is used for HTU21 and MS8607 chipsets.
> + *
> + * Return: length of sprintf on success, negative errno otherwise.
> + */
> +ssize_t ms_sensors_show_heater(struct ms_ht_dev *dev_data,
> +			       char *buf)
> +{
> +	u8 config_reg;
> +	int ret;
> +
> +	mutex_lock(&dev_data->lock);
> +	ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
> +	mutex_unlock(&dev_data->lock);
> +	if (ret)
> +		return ret;
> +
> +	return sprintf(buf, "%d\n", (config_reg & 0x4) >> 2);
> +}
> +EXPORT_SYMBOL(ms_sensors_show_heater);
> +
> +/**
> + * ms_sensors_write_heater() - Write device heater
> + * @dev_data:	pointer to temperature/humidity device data
> + * @buf:	pointer to char buffer from user space
> + * @len:	length of buf
> + *
> + * This function will write 1 or 0 value in the device
> + * to enable or disable heater.
> + * This function is used for HTU21 and MS8607 chipsets.
> + *
> + * Return: length of buffer, negative errno otherwise.
> + */
> +ssize_t ms_sensors_write_heater(struct ms_ht_dev *dev_data,
> +				const char *buf, size_t len)
> +{
> +	u8 val, config_reg;
> +	int ret;
> +
> +	ret = kstrtou8(buf, 10, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (val > 1)
> +		return -EINVAL;
> +
> +	mutex_lock(&dev_data->lock);
> +	ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
> +	if (ret) {
> +		mutex_unlock(&dev_data->lock);
> +		return ret;
> +	}
> +
> +	config_reg &= 0xFB;
> +	config_reg |= val << 2;
> +
> +	ret = i2c_smbus_write_byte_data(dev_data->client,
> +					MS_SENSORS_CONFIG_REG_WRITE,
> +					config_reg);
> +	mutex_unlock(&dev_data->lock);
> +	if (ret) {
> +		dev_err(&dev_data->client->dev, "Unable to write config register\n");
> +		return ret;
> +	}
> +
> +	return len;
> +}
> +EXPORT_SYMBOL(ms_sensors_write_heater);
> +
> +/**
> + * ms_sensors_ht_read_temperature() - Read temperature
> + * @dev_data:	pointer to temperature/humidity device data
> + * @temperature:pointer to temperature destination value
> + *
> + * This function will get temperature ADC value from the device,
> + * check the CRC and compute the temperature value.
> + * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +int ms_sensors_ht_read_temperature(struct ms_ht_dev *dev_data,
> +				   s32 *temperature)
> +{
> +	int ret;
> +	u32 adc;
> +	u16 delay;
> +
> +	mutex_lock(&dev_data->lock);
> +	delay = ms_sensors_ht_t_conversion_time[dev_data->res_index];
> +	ret = ms_sensors_convert_and_read(dev_data->client,
> +					  MS_SENSORS_HT_T_CONVERSION_START,
> +					  MS_SENSORS_NO_READ_CMD,
> +					  delay, &adc);
> +	mutex_unlock(&dev_data->lock);
> +	if (ret)
> +		return ret;
> +
> +	if (!ms_sensors_crc_valid(adc)) {
> +		dev_err(&dev_data->client->dev,
> +			"Temperature read crc check error\n");
> +		return -ENODEV;
> +	}
> +
> +	/* Temperature algorithm */
> +	*temperature = (((s64)(adc >> 8) * 175720) >> 16) - 46850;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(ms_sensors_ht_read_temperature);
> +
> +/**
> + * ms_sensors_ht_read_humidity() - Read humidity
> + * @dev_data:	pointer to temperature/humidity device data
> + * @humidity:	pointer to humidity destination value
> + *
> + * This function will get humidity ADC value from the device,
> + * check the CRC and compute the temperature value.
> + * This function is used for HTU21 and MS8607 chipsets.
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +int ms_sensors_ht_read_humidity(struct ms_ht_dev *dev_data,
> +				u32 *humidity)
> +{
> +	int ret;
> +	u32 adc;
> +	u16 delay;
> +
> +	mutex_lock(&dev_data->lock);
> +	delay = ms_sensors_ht_h_conversion_time[dev_data->res_index];
> +	ret = ms_sensors_convert_and_read(dev_data->client,
> +					  MS_SENSORS_HT_H_CONVERSION_START,
> +					  MS_SENSORS_NO_READ_CMD,
> +					  delay, &adc);
> +	mutex_unlock(&dev_data->lock);
> +	if (ret)
> +		return ret;
> +
> +	if (!ms_sensors_crc_valid(adc)) {
> +		dev_err(&dev_data->client->dev,
> +			"Humidity read crc check error\n");
> +		return -ENODEV;
> +	}
> +
> +	/* Humidity algorithm */
> +	*humidity = (((s32)(adc >> 8) * 12500) >> 16) * 10 - 6000;
> +	if (*humidity >= 100000)
> +		*humidity = 100000;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(ms_sensors_ht_read_humidity);
> +
> +/**
> + * ms_sensors_tp_crc_valid() - CRC check function for
> + *     Temperature and pressure devices.
> + *     This function is only used when reading PROM coefficients
> + *
> + * @prom:	pointer to PROM coefficients array
> + * @len:	length of PROM coefficients array
> + *
> + * Return: True if CRC is ok.
> + */
> +static bool ms_sensors_tp_crc_valid(u16 *prom, u8 len)
> +{
> +	unsigned int cnt, n_bit;
> +	u16 n_rem = 0x0000, crc_read = prom[0], crc = (*prom & 0xF000) >> 12;
> +
> +	prom[len - 1] = 0;
> +	prom[0] &= 0x0FFF;      /* Clear the CRC computation part */
> +
> +	for (cnt = 0; cnt < len * 2; cnt++) {
> +		if (cnt % 2 == 1)
> +			n_rem ^= prom[cnt >> 1] & 0x00FF;
> +		else
> +			n_rem ^= prom[cnt >> 1] >> 8;
> +
> +		for (n_bit = 8; n_bit > 0; n_bit--) {
> +			if (n_rem & 0x8000)
> +				n_rem = (n_rem << 1) ^ 0x3000;
> +			else
> +				n_rem <<= 1;
> +		}
> +	}
> +	n_rem >>= 12;
> +	prom[0] = crc_read;
> +
> +	return n_rem == crc;
> +}
> +
> +/**
> + * ms_sensors_tp_read_prom() - prom coeff read function
> + * @dev_data:	pointer to temperature/pressure device data
> + *
> + * This function will read prom coefficients and check CRC.
> + * This function is used for MS5637 and MS8607 chipsets.
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data)
> +{
> +	int i, ret;
> +
> +	for (i = 0; i < MS_SENSORS_TP_PROM_WORDS_NB; i++) {
> +		ret = ms_sensors_read_prom_word(
> +			dev_data->client,
> +			MS_SENSORS_TP_PROM_READ + (i << 1),
> +			&dev_data->prom[i]);
> +
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (!ms_sensors_tp_crc_valid(dev_data->prom,
> +				     MS_SENSORS_TP_PROM_WORDS_NB + 1)) {
> +		dev_err(&dev_data->client->dev,
> +			"Calibration coefficients crc check error\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(ms_sensors_tp_read_prom);
> +
> +/**
> + * ms_sensors_read_temp_and_pressure() - read temp and pressure
> + * @dev_data:	pointer to temperature/pressure device data
> + * @temperature:pointer to temperature destination value
> + * @pressure:	pointer to pressure destination value
> + *
> + * This function will read ADC and compute pressure and temperature value.
> + * This function is used for MS5637 and MS8607 chipsets.
> + *
> + * Return: 0 on success, negative errno otherwise.
> + */
> +int ms_sensors_read_temp_and_pressure(struct ms_tp_dev *dev_data,
> +				      int *temperature,
> +				      unsigned int *pressure)
> +{
> +	int ret;
> +	u32 t_adc, p_adc;
> +	s32 dt, temp;
> +	s64 off, sens, t2, off2, sens2;
> +	u16 *prom = dev_data->prom, delay;
> +
> +	mutex_lock(&dev_data->lock);
> +	delay = ms_sensors_tp_conversion_time[dev_data->res_index];
> +
> +	ret = ms_sensors_convert_and_read(
> +					dev_data->client,
> +					MS_SENSORS_TP_T_CONVERSION_START +
> +						dev_data->res_index * 2,
> +					MS_SENSORS_TP_ADC_READ,
> +					delay, &t_adc);
> +	if (ret) {
> +		mutex_unlock(&dev_data->lock);
> +		return ret;
> +	}
> +
> +	ret = ms_sensors_convert_and_read(
> +					dev_data->client,
> +					MS_SENSORS_TP_P_CONVERSION_START +
> +						dev_data->res_index * 2,
> +					MS_SENSORS_TP_ADC_READ,
> +					delay, &p_adc);
> +	mutex_unlock(&dev_data->lock);
> +	if (ret)
> +		return ret;
> +
> +	dt = (s32)t_adc - (prom[5] << 8);
> +
> +	/* Actual temperature = 2000 + dT * TEMPSENS */
> +	temp = 2000 + (((s64)dt * prom[6]) >> 23);
> +
> +	/* Second order temperature compensation */
> +	if (temp < 2000) {
> +		s64 tmp = (s64)temp - 2000;
> +
> +		t2 = (3 * ((s64)dt * (s64)dt)) >> 33;
> +		off2 = (61 * tmp * tmp) >> 4;
> +		sens2 = (29 * tmp * tmp) >> 4;
> +
> +		if (temp < -1500) {
> +			s64 tmp = (s64)temp + 1500;
> +
> +			off2 += 17 * tmp * tmp;
> +			sens2 += 9 * tmp * tmp;
> +		}
> +	} else {
> +		t2 = (5 * ((s64)dt * (s64)dt)) >> 38;
> +		off2 = 0;
> +		sens2 = 0;
> +	}
> +
> +	/* OFF = OFF_T1 + TCO * dT */
> +	off = (((s64)prom[2]) << 17) + ((((s64)prom[4]) * (s64)dt) >> 6);
> +	off -= off2;
> +
> +	/* Sensitivity at actual temperature = SENS_T1 + TCS * dT */
> +	sens = (((s64)prom[1]) << 16) + (((s64)prom[3] * dt) >> 7);
> +	sens -= sens2;
> +
> +	/* Temperature compensated pressure = D1 * SENS - OFF */
> +	*temperature = (temp - t2) * 10;
> +	*pressure = (u32)(((((s64)p_adc * sens) >> 21) - off) >> 15);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(ms_sensors_read_temp_and_pressure);
> +
> +MODULE_DESCRIPTION("Measurement-Specialties common i2c driver");
> +MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
> +MODULE_AUTHOR("Ludovic Tancerel <ludovic.tancerel@maplehightech.com>");
> +MODULE_LICENSE("GPL v2");
> +
> diff --git a/drivers/iio/common/ms_sensors/ms_sensors_i2c.h b/drivers/iio/common/ms_sensors/ms_sensors_i2c.h
> new file mode 100644
> index 0000000..7b614ad
> --- /dev/null
> +++ b/drivers/iio/common/ms_sensors/ms_sensors_i2c.h
> @@ -0,0 +1,66 @@
> +/*
> + * Measurements Specialties common sensor driver
> + *
> + * Copyright (c) 2015 Measurement-Specialties
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#ifndef _MS_SENSORS_I2C_H
> +#define _MS_SENSORS_I2C_H
> +
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +
> +#define MS_SENSORS_TP_PROM_WORDS_NB		7
> +
> +/**
> + * struct ms_ht_dev - Humidity/Temperature sensor device structure
> + * @client:	i2c client
> + * @lock:	lock protecting the i2c conversion
> + * @res_index:	index to selected sensor resolution
> + */
> +struct ms_ht_dev {
> +	struct i2c_client *client;
> +	struct mutex lock;
> +	u8 res_index;
> +};
> +
> +/**
> + * struct ms_tp_dev - Temperature/Pressure sensor device structure
> + * @client:	i2c client
> + * @lock:	lock protecting the i2c conversion
> + * @prom:	array of PROM coefficients used for conversion. Added element
> + *              for CRC computation
> + * @res_index:	index to selected sensor resolution
> + */
> +struct ms_tp_dev {
> +	struct i2c_client *client;
> +	struct mutex lock;
> +	u16 prom[MS_SENSORS_TP_PROM_WORDS_NB + 1];
> +	u8 res_index;
> +};
> +
> +int ms_sensors_reset(void *cli, u8 cmd, unsigned int delay);
> +int ms_sensors_read_prom_word(void *cli, int cmd, u16 *word);
> +int ms_sensors_convert_and_read(void *cli, u8 conv, u8 rd,
> +				unsigned int delay, u32 *adc);
> +int ms_sensors_read_serial(struct i2c_client *client, u64 *sn);
> +ssize_t ms_sensors_show_serial(struct ms_ht_dev *dev_data, char *buf);
> +ssize_t ms_sensors_write_resolution(struct ms_ht_dev *dev_data, u8 i);
> +ssize_t ms_sensors_show_battery_low(struct ms_ht_dev *dev_data, char *buf);
> +ssize_t ms_sensors_show_heater(struct ms_ht_dev *dev_data, char *buf);
> +ssize_t ms_sensors_write_heater(struct ms_ht_dev *dev_data,
> +				const char *buf, size_t len);
> +int ms_sensors_ht_read_temperature(struct ms_ht_dev *dev_data,
> +				   s32 *temperature);
> +int ms_sensors_ht_read_humidity(struct ms_ht_dev *dev_data,
> +				u32 *humidity);
> +int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data);
> +int ms_sensors_read_temp_and_pressure(struct ms_tp_dev *dev_data,
> +				      int *temperature,
> +				      unsigned int *pressure);
> +
> +#endif /* _MS_SENSORS_I2C_H */
>