Re: [PATCH v3] iio: add bmp280 pressure and temperature driver

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On 21/10/14 09:09, Vlad Dogaru wrote:
> Minimal implementation, can read temperature and data using direct mode.
> 
> Datasheet available at
> <http://ae-bst.resource.bosch.com/media/products/dokumente/bmp280/BST-BMP280-DS001-09.pdf>
> 
> Signed-off-by: Vlad Dogaru <vlad.dogaru@xxxxxxxxx>
v2 dropped and updated version applied to togreg.  Will push out in a few mins.

Thanks,

J
> ---
> 
> Changes since v2:
>  * use do_div() instead of the division operator for dividing 64-bit values in
>    bmp280_compensate_press().
> 
> Changes since v1:
>  * report processed values instead of raw ones;
>  * use regmap cache for calibration registers;
>  * check chip id register on probe;
>  * minor style fixes.
> 
>  drivers/iio/pressure/Kconfig  |  11 +
>  drivers/iio/pressure/Makefile |   1 +
>  drivers/iio/pressure/bmp280.c | 455 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 467 insertions(+)
>  create mode 100644 drivers/iio/pressure/bmp280.c
> 
> diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
> index 15afbc9..a3be537 100644
> --- a/drivers/iio/pressure/Kconfig
> +++ b/drivers/iio/pressure/Kconfig
> @@ -5,6 +5,17 @@
>  
>  menu "Pressure sensors"
>  
> +config BMP280
> +	tristate "Bosch Sensortec BMP280 pressure sensor driver"
> +	depends on I2C
> +	select REGMAP_I2C
> +	help
> +	 Say yes here to build support for Bosch Sensortec BMP280
> +	 pressure and temperature sensor.
> +
> +	 To compile this driver as a module, choose M here: the module
> +	 will be called bmp280.
> +
>  config HID_SENSOR_PRESS
>  	depends on HID_SENSOR_HUB
>  	select IIO_BUFFER
> diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
> index 90a37e8..88011f2 100644
> --- a/drivers/iio/pressure/Makefile
> +++ b/drivers/iio/pressure/Makefile
> @@ -3,6 +3,7 @@
>  #
>  
>  # When adding new entries keep the list in alphabetical order
> +obj-$(CONFIG_BMP280) += bmp280.o
>  obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
>  obj-$(CONFIG_MPL115) += mpl115.o
>  obj-$(CONFIG_MPL3115) += mpl3115.o
> diff --git a/drivers/iio/pressure/bmp280.c b/drivers/iio/pressure/bmp280.c
> new file mode 100644
> index 0000000..fb91cb3
> --- /dev/null
> +++ b/drivers/iio/pressure/bmp280.c
> @@ -0,0 +1,455 @@
> +/*
> + * Copyright (c) 2014 Intel Corporation
> + *
> + * Driver for Bosch Sensortec BMP280 digital pressure sensor.
> + *
> + * 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.
> + *
> + */
> +
> +#define pr_fmt(fmt) "bmp280: " fmt
> +
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/acpi.h>
> +#include <linux/regmap.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +#define BMP280_REG_TEMP_XLSB		0xFC
> +#define BMP280_REG_TEMP_LSB		0xFB
> +#define BMP280_REG_TEMP_MSB		0xFA
> +#define BMP280_REG_PRESS_XLSB		0xF9
> +#define BMP280_REG_PRESS_LSB		0xF8
> +#define BMP280_REG_PRESS_MSB		0xF7
> +
> +#define BMP280_REG_CONFIG		0xF5
> +#define BMP280_REG_CTRL_MEAS		0xF4
> +#define BMP280_REG_STATUS		0xF3
> +#define BMP280_REG_RESET		0xE0
> +#define BMP280_REG_ID			0xD0
> +
> +#define BMP280_REG_COMP_TEMP_START	0x88
> +#define BMP280_COMP_TEMP_REG_COUNT	6
> +
> +#define BMP280_REG_COMP_PRESS_START	0x8E
> +#define BMP280_COMP_PRESS_REG_COUNT	18
> +
> +#define BMP280_FILTER_MASK		(BIT(4) | BIT(3) | BIT(2))
> +#define BMP280_FILTER_OFF		0
> +#define BMP280_FILTER_2X		BIT(2)
> +#define BMP280_FILTER_4X		BIT(3)
> +#define BMP280_FILTER_8X		(BIT(3) | BIT(2))
> +#define BMP280_FILTER_16X		BIT(4)
> +
> +#define BMP280_OSRS_TEMP_MASK		(BIT(7) | BIT(6) | BIT(5))
> +#define BMP280_OSRS_TEMP_SKIP		0
> +#define BMP280_OSRS_TEMP_1X		BIT(5)
> +#define BMP280_OSRS_TEMP_2X		BIT(6)
> +#define BMP280_OSRS_TEMP_4X		(BIT(6) | BIT(5))
> +#define BMP280_OSRS_TEMP_8X		BIT(7)
> +#define BMP280_OSRS_TEMP_16X		(BIT(7) | BIT(5))
> +
> +#define BMP280_OSRS_PRESS_MASK		(BIT(4) | BIT(3) | BIT(2))
> +#define BMP280_OSRS_PRESS_SKIP		0
> +#define BMP280_OSRS_PRESS_1X		BIT(2)
> +#define BMP280_OSRS_PRESS_2X		BIT(3)
> +#define BMP280_OSRS_PRESS_4X		(BIT(3) | BIT(2))
> +#define BMP280_OSRS_PRESS_8X		BIT(4)
> +#define BMP280_OSRS_PRESS_16X		(BIT(4) | BIT(2))
> +
> +#define BMP280_MODE_MASK		(BIT(1) | BIT(0))
> +#define BMP280_MODE_SLEEP		0
> +#define BMP280_MODE_FORCED		BIT(0)
> +#define BMP280_MODE_NORMAL		(BIT(1) | BIT(0))
> +
> +#define BMP280_CHIP_ID			0x58
> +#define BMP280_SOFT_RESET_VAL		0xB6
> +
> +struct bmp280_data {
> +	struct i2c_client *client;
> +	struct mutex lock;
> +	struct regmap *regmap;
> +
> +	/*
> +	 * Carryover value from temperature conversion, used in pressure
> +	 * calculation.
> +	 */
> +	s32 t_fine;
> +};
> +
> +/* Compensation parameters. */
> +struct bmp280_comp_temp {
> +	u16 dig_t1;
> +	s16 dig_t2, dig_t3;
> +};
> +
> +struct bmp280_comp_press {
> +	u16 dig_p1;
> +	s16 dig_p2, dig_p3, dig_p4, dig_p5, dig_p6, dig_p7, dig_p8, dig_p9;
> +};
> +
> +static const struct iio_chan_spec bmp280_channels[] = {
> +	{
> +		.type = IIO_PRESSURE,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +	},
> +	{
> +		.type = IIO_TEMP,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> +	},
> +};
> +
> +static bool bmp280_is_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case BMP280_REG_CONFIG:
> +	case BMP280_REG_CTRL_MEAS:
> +	case BMP280_REG_RESET:
> +		return true;
> +	default:
> +		return false;
> +	};
> +}
> +
> +static bool bmp280_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case BMP280_REG_TEMP_XLSB:
> +	case BMP280_REG_TEMP_LSB:
> +	case BMP280_REG_TEMP_MSB:
> +	case BMP280_REG_PRESS_XLSB:
> +	case BMP280_REG_PRESS_LSB:
> +	case BMP280_REG_PRESS_MSB:
> +	case BMP280_REG_STATUS:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static const struct regmap_config bmp280_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +
> +	.max_register = BMP280_REG_TEMP_XLSB,
> +	.cache_type = REGCACHE_RBTREE,
> +
> +	.writeable_reg = bmp280_is_writeable_reg,
> +	.volatile_reg = bmp280_is_volatile_reg,
> +};
> +
> +static int bmp280_read_compensation_temp(struct bmp280_data *data,
> +					 struct bmp280_comp_temp *comp)
> +{
> +	int ret;
> +	__le16 buf[BMP280_COMP_TEMP_REG_COUNT / 2];
> +
> +	ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_TEMP_START,
> +			       buf, BMP280_COMP_TEMP_REG_COUNT);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev,
> +			"failed to read temperature calibration parameters\n");
> +		return ret;
> +	}
> +
> +	comp->dig_t1 = (u16) le16_to_cpu(buf[0]);
> +	comp->dig_t2 = (s16) le16_to_cpu(buf[1]);
> +	comp->dig_t3 = (s16) le16_to_cpu(buf[2]);
> +
> +	return 0;
> +}
> +
> +static int bmp280_read_compensation_press(struct bmp280_data *data,
> +					  struct bmp280_comp_press *comp)
> +{
> +	int ret;
> +	__le16 buf[BMP280_COMP_PRESS_REG_COUNT / 2];
> +
> +	ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_PRESS_START,
> +			       buf, BMP280_COMP_PRESS_REG_COUNT);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev,
> +			"failed to read pressure calibration parameters\n");
> +		return ret;
> +	}
> +
> +	comp->dig_p1 = (s16) le16_to_cpu(buf[0]);
> +	comp->dig_p2 = (u16) le16_to_cpu(buf[1]);
> +	comp->dig_p3 = (u16) le16_to_cpu(buf[2]);
> +	comp->dig_p4 = (u16) le16_to_cpu(buf[3]);
> +	comp->dig_p5 = (u16) le16_to_cpu(buf[4]);
> +	comp->dig_p6 = (u16) le16_to_cpu(buf[5]);
> +	comp->dig_p7 = (u16) le16_to_cpu(buf[6]);
> +	comp->dig_p8 = (u16) le16_to_cpu(buf[7]);
> +	comp->dig_p9 = (u16) le16_to_cpu(buf[8]);
> +
> +	return 0;
> +}
> +
> +/*
> + * Returns temperature in DegC, resolution is 0.01 DegC.  Output value of
> + * "5123" equals 51.23 DegC.  t_fine carries fine temperature as global
> + * value.
> + *
> + * Taken from datasheet, Section 3.11.3, "Compensation formula".
> + */
> +static s32 bmp280_compensate_temp(struct bmp280_data *data,
> +				  struct bmp280_comp_temp *comp,
> +				  s32 adc_temp)
> +{
> +	s32 var1, var2, t;
> +
> +	var1 = (((adc_temp >> 3) - ((s32) comp->dig_t1 << 1)) *
> +		((s32) comp->dig_t2)) >> 11;
> +	var2 = (((((adc_temp >> 4) - ((s32) comp->dig_t1)) *
> +		  ((adc_temp >> 4) - ((s32) comp->dig_t1))) >> 12) *
> +		((s32) comp->dig_t3)) >> 14;
> +
> +	data->t_fine = var1 + var2;
> +	t = (data->t_fine * 5 + 128) >> 8;
> +
> +	return t;
> +}
> +
> +/*
> + * Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24
> + * integer bits and 8 fractional bits).  Output value of "24674867"
> + * represents 24674867/256 = 96386.2 Pa = 963.862 hPa
> + *
> + * Taken from datasheet, Section 3.11.3, "Compensation formula".
> + */
> +static u32 bmp280_compensate_press(struct bmp280_data *data,
> +				   struct bmp280_comp_press *comp,
> +				   s32 adc_press)
> +{
> +	s64 var1, var2, p;
> +
> +	var1 = ((s64) data->t_fine) - 128000;
> +	var2 = var1 * var1 * (s64) comp->dig_p6;
> +	var2 = var2 + ((var1 * (s64) comp->dig_p5) << 17);
> +	var2 = var2 + (((s64) comp->dig_p4) << 35);
> +	var1 = ((var1 * var1 * (s64) comp->dig_p3) >> 8) +
> +		((var1 * (s64) comp->dig_p2) << 12);
> +	var1 = (((((s64) 1) << 47) + var1)) * ((s64) comp->dig_p1) >> 33;
> +
> +	if (var1 == 0)
> +		return 0;
> +
> +	p = ((((s64) 1048576 - adc_press) << 31) - var2) * 3125;
> +	do_div(p, var1);
> +	var1 = (((s64) comp->dig_p9) * (p >> 13) * (p >> 13)) >> 25;
> +	var2 = (((s64) comp->dig_p8) * p) >> 19;
> +	p = ((p + var1 + var2) >> 8) + (((s64) comp->dig_p7) << 4);
> +
> +	return (u32) p;
> +}
> +
> +static int bmp280_read_temp(struct bmp280_data *data,
> +			    int *val)
> +{
> +	int ret;
> +	__be32 tmp = 0;
> +	s32 adc_temp, comp_temp;
> +	struct bmp280_comp_temp comp;
> +
> +	ret = bmp280_read_compensation_temp(data, &comp);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_bulk_read(data->regmap, BMP280_REG_TEMP_MSB,
> +			       (u8 *) &tmp, 3);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "failed to read temperature\n");
> +		return ret;
> +	}
> +
> +	adc_temp = be32_to_cpu(tmp) >> 12;
> +	comp_temp = bmp280_compensate_temp(data, &comp, adc_temp);
> +
> +	/*
> +	 * val might be NULL if we're called by the read_press routine,
> +	 * who only cares about the carry over t_fine value.
> +	 */
> +	if (val) {
> +		*val = comp_temp * 10;
> +		return IIO_VAL_INT;
> +	}
> +
> +	return 0;
> +}
> +
> +static int bmp280_read_press(struct bmp280_data *data,
> +			     int *val, int *val2)
> +{
> +	int ret;
> +	__be32 tmp = 0;
> +	s32 adc_press;
> +	u32 comp_press;
> +	struct bmp280_comp_press comp;
> +
> +	ret = bmp280_read_compensation_press(data, &comp);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Read and compensate temperature so we get a reading of t_fine. */
> +	ret = bmp280_read_temp(data, NULL);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB,
> +			       (u8 *) &tmp, 3);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev, "failed to read pressure\n");
> +		return ret;
> +	}
> +
> +	adc_press = be32_to_cpu(tmp) >> 12;
> +	comp_press = bmp280_compensate_press(data, &comp, adc_press);
> +
> +	*val = comp_press / 256000;
> +	*val2 = comp_press * 1000000 / 256000;
> +
> +	return IIO_VAL_INT_PLUS_MICRO;
> +}
> +
> +static int bmp280_read_raw(struct iio_dev *indio_dev,
> +			   struct iio_chan_spec const *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	int ret;
> +	struct bmp280_data *data = iio_priv(indio_dev);
> +
> +	mutex_lock(&data->lock);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		switch (chan->type) {
> +		case IIO_PRESSURE:
> +			ret = bmp280_read_press(data, val, val2);
> +			break;
> +		case IIO_TEMP:
> +			ret = bmp280_read_temp(data, val);
> +			break;
> +		default:
> +			ret = -EINVAL;
> +			break;
> +		}
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	mutex_unlock(&data->lock);
> +
> +	return ret;
> +}
> +
> +static const struct iio_info bmp280_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw = &bmp280_read_raw,
> +};
> +
> +static int bmp280_chip_init(struct bmp280_data *data)
> +{
> +	int ret;
> +
> +	ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_MEAS,
> +				 BMP280_OSRS_TEMP_MASK |
> +				 BMP280_OSRS_PRESS_MASK |
> +				 BMP280_MODE_MASK,
> +				 BMP280_OSRS_TEMP_2X |
> +				 BMP280_OSRS_PRESS_16X |
> +				 BMP280_MODE_NORMAL);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev,
> +			"failed to write config register\n");
> +		return ret;
> +	}
> +
> +	ret = regmap_update_bits(data->regmap, BMP280_REG_CONFIG,
> +				 BMP280_FILTER_MASK,
> +				 BMP280_FILTER_4X);
> +	if (ret < 0) {
> +		dev_err(&data->client->dev,
> +			"failed to write config register\n");
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static int bmp280_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	int ret;
> +	struct iio_dev *indio_dev;
> +	struct bmp280_data *data;
> +	unsigned int chip_id;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +	data = iio_priv(indio_dev);
> +	mutex_init(&data->lock);
> +	data->client = client;
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->name = id->name;
> +	indio_dev->channels = bmp280_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(bmp280_channels);
> +	indio_dev->info = &bmp280_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	data->regmap = devm_regmap_init_i2c(client, &bmp280_regmap_config);
> +	if (IS_ERR(data->regmap)) {
> +		dev_err(&client->dev, "failed to allocate register map\n");
> +		return PTR_ERR(data->regmap);
> +	}
> +
> +	ret = regmap_read(data->regmap, BMP280_REG_ID, &chip_id);
> +	if (ret < 0)
> +		return ret;
> +	if (chip_id != BMP280_CHIP_ID) {
> +		dev_err(&client->dev, "bad chip id.  expected %x got %x\n",
> +			BMP280_CHIP_ID, chip_id);
> +		return -EINVAL;
> +	}
> +
> +	ret = bmp280_chip_init(data);
> +	if (ret < 0)
> +		return ret;
> +
> +	return devm_iio_device_register(&client->dev, indio_dev);
> +}
> +
> +static const struct acpi_device_id bmp280_acpi_match[] = {
> +	{"BMP0280", 0},
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(acpi, bmp280_acpi_match);
> +
> +static const struct i2c_device_id bmp280_id[] = {
> +	{"bmp280", 0},
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(i2c, bmp280_id);
> +
> +static struct i2c_driver bmp280_driver = {
> +	.driver = {
> +		.name	= "bmp280",
> +		.acpi_match_table = ACPI_PTR(bmp280_acpi_match),
> +	},
> +	.probe		= bmp280_probe,
> +	.id_table	= bmp280_id,
> +};
> +module_i2c_driver(bmp280_driver);
> +
> +MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP280 pressure and temperature sensor");
> +MODULE_LICENSE("GPL v2");
> 
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