Date:	Sun, 8 Mar 2015 19:16:00 +0100 (CET)
From:	Peter Meerwald <pmeerw@...erw.net>
To:	Tomasz Duszynski <tduszyns@...il.com>
cc:	jic23@...nel.org, knaack.h@....de, lars@...afoo.de,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH] iio: pressure: add support for MS5611 pressure and
 temperature sensor

> Add support for Measurement Specialities MS5611 pressure
> and temperature sensor.

comments inline below
 
> Signed-off-by: Tomasz Duszynski <tduszyns@...il.com>
> ---
>  drivers/iio/pressure/Kconfig       |  27 +++++
>  drivers/iio/pressure/Makefile      |   4 +
>  drivers/iio/pressure/ms5611.h      |  44 +++++++
>  drivers/iio/pressure/ms5611_core.c | 239 +++++++++++++++++++++++++++++++++++++
>  drivers/iio/pressure/ms5611_i2c.c  | 131 ++++++++++++++++++++
>  drivers/iio/pressure/ms5611_spi.c  | 137 +++++++++++++++++++++
>  6 files changed, 582 insertions(+)
>  create mode 100644 drivers/iio/pressure/ms5611.h
>  create mode 100644 drivers/iio/pressure/ms5611_core.c
>  create mode 100644 drivers/iio/pressure/ms5611_i2c.c
>  create mode 100644 drivers/iio/pressure/ms5611_spi.c
> 
> diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
> index a3be537..fa62950 100644
> --- a/drivers/iio/pressure/Kconfig
> +++ b/drivers/iio/pressure/Kconfig
> @@ -52,6 +52,33 @@ config MPL3115
>            To compile this driver as a module, choose M here: the module
>            will be called mpl3115.
>  
> +config MS5611
> +	tristate "Measurement Specialities MS5611 pressure sensor driver"
> +	help
> +	  Say Y here to build support for the Measurement Specialities
> +	  MS5611 pressure and temperature sensor.
> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called ms5611_core.
> +
> +config MS5611_I2C
> +	tristate "support I2C bus connection"
> +	depends on I2C && MS5611
> +	help
> +	  Say Y here to build I2C bus support for MS5611.
> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called ms5611_i2c.
> +
> +config MS5611_SPI
> +	tristate "support SPI bus connection"
> +	depends on SPI_MASTER && MS5611
> +	help
> +	  Say Y here to build SPI bus support for MS5611.
> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called ms5611_spi.
> +
>  config IIO_ST_PRESS
>  	tristate "STMicroelectronics pressure sensor Driver"
>  	depends on (I2C || SPI_MASTER) && SYSFS
> diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
> index 88011f2..82f34f6 100644
> --- a/drivers/iio/pressure/Makefile
> +++ b/drivers/iio/pressure/Makefile
> @@ -14,3 +14,7 @@ obj-$(CONFIG_T5403) += t5403.o
>  
>  obj-$(CONFIG_IIO_ST_PRESS_I2C) += st_pressure_i2c.o
>  obj-$(CONFIG_IIO_ST_PRESS_SPI) += st_pressure_spi.o
> +

alphebetic order?

> +obj-$(CONFIG_MS5611) += ms5611_core.o
> +obj-$(CONFIG_MS5611_I2C) += ms5611_i2c.o
> +obj-$(CONFIG_MS5611_SPI) += ms5611_spi.o
> diff --git a/drivers/iio/pressure/ms5611.h b/drivers/iio/pressure/ms5611.h
> new file mode 100644
> index 0000000..f4d44a5
> --- /dev/null
> +++ b/drivers/iio/pressure/ms5611.h
> @@ -0,0 +1,44 @@
> +/*
> + * MS5611 pressure and temperature sensor driver
> + *
> + * Copyright (c) Tomasz Duszynski <tduszyns@...il.com>
> + *
> + * 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 _MS5611_H
> +#define _MS5611_H
> +
> +#include <linux/device.h>
> +#include <linux/iio/iio.h>
> +#include <linux/mutex.h>
> +
> +#define MS5611_RESET			0x1e
> +#define MS5611_READ_ADC			0x00
> +#define MS5611_READ_PROM_WORD		0xA0
> +#define MS5611_START_TEMP_CONV		0x58
> +#define MS5611_START_PRESSURE_CONV	0x48
> +
> +#define MS5611_CONV_TIME_MIN		9040
> +#define MS5611_CONV_TIME_MAX		10000
> +
> +#define MS5611_PROM_WORDS_NB		8
> +
> +struct ms5611_state {
> +	void *client;
> +	struct mutex lock;
> +
> +	int (*reset)(struct device *dev);
> +	int (*read_prom_word)(struct device *dev, int index, u16 *word);
> +	int (*read_adc_temp_and_pressure)(struct device *dev,
> +					  s32 *temp, s32 *pressure);
> +

probably regmap could be used to avoid duplicate code?

> +	u16 prom[MS5611_PROM_WORDS_NB];
> +};
> +
> +int ms5611_probe(struct iio_dev *indio_dev, struct device *dev);
> +int ms5611_remove(struct iio_dev *indio_dev);
> +
> +#endif /* _MS5611_H */
> diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c
> new file mode 100644
> index 0000000..e4deda7
> --- /dev/null
> +++ b/drivers/iio/pressure/ms5611_core.c
> @@ -0,0 +1,239 @@
> +/*
> + * MS5611 pressure and temperature sensor driver
> + *
> + * Copyright (c) Tomasz Duszynski <tduszyns@...il.com>
> + *
> + * 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.
> + *
> + * Data sheet:
> + *  http://www.meas-spec.com/downloads/MS5611-01BA03.pdf
> + *
> + */
> +#include <linux/module.h>
> +#include <linux/iio/iio.h>
> +#include <linux/delay.h>
> +
> +#include "ms5611.h"
> +
> +static bool ms5611_prom_is_valid(u16 *prom, size_t len)
> +{
> +	int i, j;
> +	uint16_t crc = 0, crc_orig = prom[7] & 0x000F;
> +
> +	prom[7] &= 0xFF00;
> +
> +	for (i = 0; i < len * 2; i++) {
> +		if (i % 2 == 1)
> +			crc ^= prom[i >> 1] & 0x00FF;
> +		else
> +			crc ^= prom[i >> 1] >> 8;
> +
> +		for (j = 0; j < 8; j++) {
> +			if (crc & 0x8000)
> +				crc = (crc << 1) ^ 0x3000;
> +			else
> +				crc <<= 1;
> +		}
> +	}
> +
> +	crc = (crc >> 12) & 0x000F;
> +	return crc_orig != 0x0000 && crc == crc_orig;
> +}
> +
> +static int ms5611_read_prom(struct iio_dev *indio_dev)
> +{
> +	int ret, i;
> +	struct ms5611_state *st = iio_priv(indio_dev);
> +
> +	for (i = 0; i < MS5611_PROM_WORDS_NB; i++) {
> +		ret = st->read_prom_word(&indio_dev->dev, i, &st->prom[i]);
> +		if (ret < 0) {
> +			dev_err(&indio_dev->dev,
> +				"failed to read prom at %d\n", i);
> +			return ret;
> +		}
> +	}
> +
> +	if (!ms5611_prom_is_valid(st->prom, MS5611_PROM_WORDS_NB)) {
> +		dev_err(&indio_dev->dev, "PROM integrity check failed\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
> +					 s32 *temp, s32 *pressure)
> +{
> +	int ret;
> +	s32 t, p;
> +	s64 off, off2, sens, sens2, dt, t2 = 0;

some of the variables could be declared with a more local scope, such as 
tmp below (e.g. sens2)

> +	struct ms5611_state *st = iio_priv(indio_dev);
> +
> +	ret = st->read_adc_temp_and_pressure(&indio_dev->dev, &t, &p);
> +	if (ret < 0) {
> +		dev_err(&indio_dev->dev,
> +			"failed to read temperature and pressure\n");
> +		return ret;
> +	}
> +
> +	dt = t - (st->prom[5] << 8);
> +	off = ((s64)st->prom[2] << 16) + ((st->prom[4] * dt) >> 7);
> +	sens = ((s64)st->prom[1] << 15) + ((st->prom[3] * dt) >> 8);
> +
> +	t = 2000 + ((st->prom[6] * dt) >> 23);
> +	if (t < 2000) {
> +		t2 = (dt * dt) >> 31;
> +		off2 = (5 * (t - 2000) * (t - 2000)) >> 1;
> +		sens2 = off2 >> 1;
> +
> +		if (t < -1500) {
> +			s64 tmp = (t + 1500) * (t + 1500);
> +
> +			off2 += 7 * tmp;
> +			sens2 += (11 * tmp) >> 1;
> +		}
> +
> +		off -= off2;
> +		sens -= sens2;
> +	}
> +
> +	*temp = t - t2;
> +	*pressure = (((p * sens) >> 21) - off) >> 15;

probably newline here makes it look nicer

> +	return 0;
> +}
> +
> +static int ms5611_reset(struct iio_dev *indio_dev)
> +{
> +	int ret;
> +	struct ms5611_state *st = iio_priv(indio_dev);
> +
> +	ret = st->reset(&indio_dev->dev);
> +	if (ret < 0) {
> +		dev_err(&indio_dev->dev, "failed to reset device\n");
> +		return ret;
> +	}
> +
> +	usleep_range(3000, 4000);
> +	return 0;
> +}
> +
> +static int ms5611_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	int ret;
> +	s32 temp, pressure;
> +	struct ms5611_state *st = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		mutex_lock(&st->lock);
> +		ret = ms5611_read_temp_and_pressure(indio_dev,
> +						    &temp, &pressure);
> +		mutex_unlock(&st->lock);
> +		if (ret < 0)
> +			break;
> +
> +		switch (chan->type) {
> +		case IIO_TEMP:
> +			*val = temp;
> +			ret = IIO_VAL_INT;
> +			break;
> +		case IIO_PRESSURE:
> +			*val = pressure;
> +			ret = IIO_VAL_INT;
> +			break;
> +		default:
> +			ret = -EINVAL;

probably return -EINVAL directly

> +		}

probably return IIO_VAL_INT here

> +		break;
> +	case IIO_CHAN_INFO_SCALE:

SCALE is not necessary when _PROCESSED is already doing all the scaling 
such that the output is in milli-Celsius and kilo-Pascal

> +		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;
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct iio_chan_spec ms5611_channels[] = {
> +	{
> +		.type = IIO_PRESSURE,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +			BIT(IIO_CHAN_INFO_SCALE)
> +	},
> +	{
> +		.type = IIO_TEMP,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> +			BIT(IIO_CHAN_INFO_SCALE)
> +	}
> +};
> +
> +static const struct iio_info ms5611_info = {
> +	.read_raw = &ms5611_read_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int ms5611_init(struct iio_dev *indio_dev)
> +{
> +	int ret;
> +
> +	ret = ms5611_reset(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ms5611_read_prom(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +int ms5611_probe(struct iio_dev *indio_dev, struct device *dev)
> +{
> +	int ret;
> +	struct ms5611_state *st = iio_priv(indio_dev);
> +
> +	mutex_init(&st->lock);
> +	indio_dev->dev.parent = dev;
> +	indio_dev->name = dev->driver->name;
> +	indio_dev->info = &ms5611_info;
> +	indio_dev->channels = ms5611_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(ms5611_channels);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ret = ms5611_init(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	return iio_device_register(indio_dev);

use devm_iio_device_register() and save _remove()

> +}
> +EXPORT_SYMBOL(ms5611_probe);
> +
> +int ms5611_remove(struct iio_dev *indio_dev)
> +{
> +	iio_device_unregister(indio_dev);
> +	return 0;
> +}
> +EXPORT_SYMBOL(ms5611_remove);
> +
> +MODULE_AUTHOR("Tomasz Duszynski <tduszyns@...il.com>");
> +MODULE_DESCRIPTION("MS5611 core driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/pressure/ms5611_i2c.c b/drivers/iio/pressure/ms5611_i2c.c
> new file mode 100644
> index 0000000..920fa78
> --- /dev/null
> +++ b/drivers/iio/pressure/ms5611_i2c.c
> @@ -0,0 +1,131 @@
> +/*
> + * MS5611 pressure and temperature sensor driver (I2C bus)
> + *
> + * Copyright (c) Tomasz Duszynski <tduszyns@...il.com>
> + *
> + * 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.
> + *
> + */
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +
> +#include "ms5611.h"
> +
> +static int ms5611_reset(struct device *dev)
> +{
> +	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> +
> +	return i2c_smbus_write_byte(st->client, MS5611_RESET);
> +}
> +
> +static int ms5611_read_prom_word(struct device *dev, int index, u16 *word)
> +{
> +	int ret;
> +	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> +
> +	ret = i2c_smbus_read_word_swapped(st->client,
> +			MS5611_READ_PROM_WORD + (index << 1));
> +	if (ret < 0)
> +		return ret;
> +
> +	*word = ret;
> +	return 0;
> +}
> +
> +static int ms5611_read_adc(struct ms5611_state *st, s32 *val)
> +{
> +	int ret;
> +	u8 buf[3];
> +
> +	ret = i2c_smbus_read_i2c_block_data(st->client, MS5611_READ_ADC,
> +					    3, buf);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = (buf[0] << 16) | (buf[1] << 8) | buf[0];

should be buf[2] at the end

> +	return 0;
> +}
> +
> +static int ms5611_read_adc_temp_and_pressure(struct device *dev,
> +					     s32 *temp, s32 *pressure)
> +{
> +	int ret;
> +	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> +
> +	ret = i2c_smbus_write_byte(st->client, MS5611_START_TEMP_CONV);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
> +
> +	ret = ms5611_read_adc(st, temp);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = i2c_smbus_write_byte(st->client, MS5611_START_PRESSURE_CONV);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
> +
> +	ret = ms5611_read_adc(st, pressure);
> +	if (ret < 0)
> +		return ret;

just return ret?

> +
> +	return 0;
> +}
> +
> +static int ms5611_i2c_probe(struct i2c_client *client,
> +			    const struct i2c_device_id *id)
> +{
> +	struct ms5611_state *st;
> +	struct iio_dev *indio_dev;
> +
> +	if (!i2c_check_functionality(client->adapter,
> +				     I2C_FUNC_SMBUS_WRITE_BYTE |
> +				     I2C_FUNC_SMBUS_READ_WORD_DATA |
> +				     I2C_FUNC_SMBUS_READ_I2C_BLOCK))
> +		return -ENODEV;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +	st = iio_priv(indio_dev);
> +	st->reset = ms5611_reset;
> +	st->read_prom_word = ms5611_read_prom_word;
> +	st->read_adc_temp_and_pressure = ms5611_read_adc_temp_and_pressure;
> +	st->client = client;
> +
> +	return ms5611_probe(indio_dev, &client->dev);
> +}
> +
> +static int ms5611_i2c_remove(struct i2c_client *client)
> +{
> +	return ms5611_remove(i2c_get_clientdata(client));
> +}
> +
> +static const struct i2c_device_id ms5611_id[] = {
> +	{ "ms5611", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, ms5611_id);
> +
> +static struct i2c_driver ms5611_driver = {
> +	.driver = {
> +		.name = "ms5611",
> +		.owner = THIS_MODULE,
> +	},
> +	.id_table = ms5611_id,
> +	.probe = ms5611_i2c_probe,
> +	.remove = ms5611_i2c_remove,
> +};
> +module_i2c_driver(ms5611_driver);
> +
> +MODULE_AUTHOR("Tomasz Duszynski <tduszyns@...il.com>");
> +MODULE_DESCRIPTION("MS5611 i2c driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/iio/pressure/ms5611_spi.c b/drivers/iio/pressure/ms5611_spi.c
> new file mode 100644
> index 0000000..eb3fee5
> --- /dev/null
> +++ b/drivers/iio/pressure/ms5611_spi.c
> @@ -0,0 +1,137 @@
> +/*
> + * MS5611 pressure and temperature sensor driver (SPI bus)
> + *
> + * Copyright (c) Tomasz Duszynski <tduszyns@...il.com>
> + *
> + * 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.
> + *
> + */
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/spi/spi.h>
> +
> +#include "ms5611.h"
> +
> +static int ms5611_reset(struct device *dev)
> +{
> +	u8 cmd = MS5611_RESET;
> +	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> +
> +	return spi_write(st->client, &cmd, 1);
> +}
> +
> +static int ms5611_read_prom_word(struct device *dev, int index, u16 *word)
> +{
> +	int ret;
> +	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> +
> +	ret = spi_w8r16be(st->client, MS5611_READ_PROM_WORD + (index << 1));
> +	if (ret < 0)
> +		return ret;
> +
> +	*word = ret;
> +	return 0;
> +}
> +
> +static int ms5611_read_adc(struct device *dev, s32 *val)
> +{
> +	int ret;
> +	u8 buf[3];
> +	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> +
> +	buf[0] = MS5611_READ_ADC;
> +
> +	ret = spi_write_then_read(st->client, buf, 1, buf, 3);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = (buf[0] << 16) | (buf[1] << 8) | buf[0];

buf[2]?

> +	return 0;
> +}
> +
> +static int ms5611_read_adc_temp_and_pressure(struct device *dev,
> +					     s32 *temp, s32 *pressure)
> +{
> +	u8 cmd;
> +	int ret;
> +	struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> +
> +	cmd = MS5611_START_TEMP_CONV;
> +	ret = spi_write(st->client, &cmd, 1);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
> +
> +	ret = ms5611_read_adc(dev, temp);
> +	if (ret < 0)
> +		return ret;
> +
> +	cmd = MS5611_START_PRESSURE_CONV;
> +	ret = spi_write(st->client, &cmd, 1);
> +	if (ret < 0)
> +		return ret;
> +
> +	usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
> +
> +	ret = ms5611_read_adc(dev, pressure);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int ms5611_spi_probe(struct spi_device *spi)
> +{
> +	int ret;
> +	struct ms5611_state *st;
> +	struct iio_dev *indio_dev;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	spi->mode = SPI_MODE_0;
> +	spi->max_speed_hz = 20000000;
> +	spi->bits_per_word = 8;
> +	ret = spi_setup(spi);
> +	if (ret < 0)
> +		return ret;
> +
> +	spi_set_drvdata(spi, indio_dev);
> +	st = iio_priv(indio_dev);
> +	st->reset = ms5611_reset;
> +	st->read_prom_word = ms5611_read_prom_word;
> +	st->read_adc_temp_and_pressure = ms5611_read_adc_temp_and_pressure;
> +	st->client = spi;
> +
> +	return ms5611_probe(indio_dev, &spi->dev);
> +}
> +
> +static int ms5611_spi_remove(struct spi_device *spi)
> +{
> +	return ms5611_remove(spi_get_drvdata(spi));
> +}
> +
> +static const struct spi_device_id ms5611_id[] = {
> +	{ "ms5611", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(spi, ms5611_id);
> +
> +static struct spi_driver ms5611_driver = {
> +	.driver = {
> +		.name = "ms5611",
> +		.owner = THIS_MODULE,
> +	},
> +	.id_table = ms5611_id,
> +	.probe = ms5611_spi_probe,
> +	.remove = ms5611_spi_remove,
> +};
> +module_spi_driver(ms5611_driver);
> +
> +MODULE_AUTHOR("Tomasz Duszynski <tduszyns@...il.com>");
> +MODULE_DESCRIPTION("MS5611 spi driver");
> +MODULE_LICENSE("GPL v2");
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)
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