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iio: pressure: bmp280: add humidity support
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Enable humidity support for the BME280 part

Signed-off-by: Matt Ranostay <matt.ranostay@intel.com>
Acked-by: Vlad Dogaru <vlad.dogaru@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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Matt Ranostay authored and Jonathan Cameron committed May 21, 2016
1 parent b7a96bb commit 14beaa8
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Showing 2 changed files with 200 additions and 3 deletions.
3 changes: 2 additions & 1 deletion drivers/iio/pressure/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,8 @@ config BMP280
select REGMAP_I2C
help
Say yes here to build support for Bosch Sensortec BMP180 and BMP280
pressure and temperature sensors.
pressure and temperature sensors. Also supports the BE280 with
an additional humidty sensor channel.

To compile this driver as a module, choose M here: the module
will be called bmp280.
Expand Down
200 changes: 198 additions & 2 deletions drivers/iio/pressure/bmp280.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
* Datasheet:
* https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP180-DS000-121.pdf
* https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP280-DS001-12.pdf
* https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-11.pdf
*/

#define pr_fmt(fmt) "bmp280: " fmt
Expand All @@ -23,6 +24,8 @@
#include <linux/iio/sysfs.h>

/* BMP280 specific registers */
#define BMP280_REG_HUMIDITY_LSB 0xFE
#define BMP280_REG_HUMIDITY_MSB 0xFD
#define BMP280_REG_TEMP_XLSB 0xFC
#define BMP280_REG_TEMP_LSB 0xFB
#define BMP280_REG_TEMP_MSB 0xFA
Expand All @@ -31,7 +34,17 @@
#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_CTRL_HUMIDITY 0xF2

/* Due to non linear mapping, and data sizes we can't do a bulk read */
#define BMP280_REG_COMP_H1 0xA1
#define BMP280_REG_COMP_H2 0xE1
#define BMP280_REG_COMP_H3 0xE3
#define BMP280_REG_COMP_H4 0xE4
#define BMP280_REG_COMP_H5 0xE5
#define BMP280_REG_COMP_H6 0xE7

#define BMP280_REG_COMP_TEMP_START 0x88
#define BMP280_COMP_TEMP_REG_COUNT 6
Expand All @@ -46,6 +59,15 @@
#define BMP280_FILTER_8X (BIT(3) | BIT(2))
#define BMP280_FILTER_16X BIT(4)

#define BMP280_OSRS_HUMIDITY_MASK (BIT(2) | BIT(1) | BIT(0))
#define BMP280_OSRS_HUMIDITIY_X(osrs_h) ((osrs_h) << 0)
#define BMP280_OSRS_HUMIDITY_SKIP 0
#define BMP280_OSRS_HUMIDITY_1X BMP280_OSRS_HUMIDITIY_X(1)
#define BMP280_OSRS_HUMIDITY_2X BMP280_OSRS_HUMIDITIY_X(2)
#define BMP280_OSRS_HUMIDITY_4X BMP280_OSRS_HUMIDITIY_X(3)
#define BMP280_OSRS_HUMIDITY_8X BMP280_OSRS_HUMIDITIY_X(4)
#define BMP280_OSRS_HUMIDITY_16X BMP280_OSRS_HUMIDITIY_X(5)

#define BMP280_OSRS_TEMP_MASK (BIT(7) | BIT(6) | BIT(5))
#define BMP280_OSRS_TEMP_SKIP 0
#define BMP280_OSRS_TEMP_X(osrs_t) ((osrs_t) << 5)
Expand Down Expand Up @@ -92,6 +114,7 @@

#define BMP180_CHIP_ID 0x55
#define BMP280_CHIP_ID 0x58
#define BME280_CHIP_ID 0x60
#define BMP280_SOFT_RESET_VAL 0xB6

struct bmp280_data {
Expand All @@ -103,6 +126,7 @@ struct bmp280_data {
/* log of base 2 of oversampling rate */
u8 oversampling_press;
u8 oversampling_temp;
u8 oversampling_humid;

/*
* Carryover value from temperature conversion, used in pressure
Expand All @@ -120,9 +144,13 @@ struct bmp280_chip_info {
const int *oversampling_press_avail;
int num_oversampling_press_avail;

const int *oversampling_humid_avail;
int num_oversampling_humid_avail;

int (*chip_config)(struct bmp280_data *);
int (*read_temp)(struct bmp280_data *, int *);
int (*read_press)(struct bmp280_data *, int *, int *);
int (*read_humid)(struct bmp280_data *, int *, int *);
};

/*
Expand All @@ -143,12 +171,18 @@ static const struct iio_chan_spec bmp280_channels[] = {
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
},
{
.type = IIO_HUMIDITYRELATIVE,
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
},
};

static bool bmp280_is_writeable_reg(struct device *dev, unsigned int reg)
{
switch (reg) {
case BMP280_REG_CONFIG:
case BMP280_REG_CTRL_HUMIDITY:
case BMP280_REG_CTRL_MEAS:
case BMP280_REG_RESET:
return true;
Expand All @@ -160,6 +194,8 @@ static bool bmp280_is_writeable_reg(struct device *dev, unsigned int reg)
static bool bmp280_is_volatile_reg(struct device *dev, unsigned int reg)
{
switch (reg) {
case BMP280_REG_HUMIDITY_LSB:
case BMP280_REG_HUMIDITY_MSB:
case BMP280_REG_TEMP_XLSB:
case BMP280_REG_TEMP_LSB:
case BMP280_REG_TEMP_MSB:
Expand All @@ -177,13 +213,77 @@ static const struct regmap_config bmp280_regmap_config = {
.reg_bits = 8,
.val_bits = 8,

.max_register = BMP280_REG_TEMP_XLSB,
.max_register = BMP280_REG_HUMIDITY_LSB,
.cache_type = REGCACHE_RBTREE,

.writeable_reg = bmp280_is_writeable_reg,
.volatile_reg = bmp280_is_volatile_reg,
};

/*
* Returns humidity in percent, resolution is 0.01 percent. Output value of
* "47445" represents 47445/1024 = 46.333 %RH.
*
* Taken from BME280 datasheet, Section 4.2.3, "Compensation formula".
*/

static u32 bmp280_compensate_humidity(struct bmp280_data *data,
s32 adc_humidity)
{
struct device *dev = &data->client->dev;
unsigned int H1, H3, tmp;
int H2, H4, H5, H6, ret, var;

ret = regmap_read(data->regmap, BMP280_REG_COMP_H1, &H1);
if (ret < 0) {
dev_err(dev, "failed to read H1 comp value\n");
return ret;
}

ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H2, &tmp, 2);
if (ret < 0) {
dev_err(dev, "failed to read H2 comp value\n");
return ret;
}
H2 = sign_extend32(le16_to_cpu(tmp), 15);

ret = regmap_read(data->regmap, BMP280_REG_COMP_H3, &H3);
if (ret < 0) {
dev_err(dev, "failed to read H3 comp value\n");
return ret;
}

ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H4, &tmp, 2);
if (ret < 0) {
dev_err(dev, "failed to read H4 comp value\n");
return ret;
}
H4 = sign_extend32(((be16_to_cpu(tmp) >> 4) & 0xff0) |
(be16_to_cpu(tmp) & 0xf), 11);

ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H5, &tmp, 2);
if (ret < 0) {
dev_err(dev, "failed to read H5 comp value\n");
return ret;
}
H5 = sign_extend32(((le16_to_cpu(tmp) >> 4) & 0xfff), 11);

ret = regmap_read(data->regmap, BMP280_REG_COMP_H6, &tmp);
if (ret < 0) {
dev_err(dev, "failed to read H6 comp value\n");
return ret;
}
H6 = sign_extend32(tmp, 7);

var = ((s32)data->t_fine) - 76800;
var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var)) + 16384) >> 15)
* (((((((var * H6) >> 10) * (((var * H3) >> 11) + 32768)) >> 10)
+ 2097152) * H2 + 8192) >> 14);
var -= ((((var >> 15) * (var >> 15)) >> 7) * H1) >> 4;

return var >> 12;
};

/*
* Returns temperature in DegC, resolution is 0.01 DegC. Output value of
* "5123" equals 51.23 DegC. t_fine carries fine temperature as global
Expand Down Expand Up @@ -324,6 +424,34 @@ static int bmp280_read_press(struct bmp280_data *data,
return IIO_VAL_FRACTIONAL;
}

static int bmp280_read_humid(struct bmp280_data *data, int *val, int *val2)
{
int ret;
__be16 tmp = 0;
s32 adc_humidity;
u32 comp_humidity;

/* 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_HUMIDITY_MSB,
(u8 *) &tmp, 2);
if (ret < 0) {
dev_err(&data->client->dev, "failed to read humidity\n");
return ret;
}

adc_humidity = be16_to_cpu(tmp);
comp_humidity = bmp280_compensate_humidity(data, adc_humidity);

*val = comp_humidity;
*val2 = 1024;

return IIO_VAL_FRACTIONAL;
}

static int bmp280_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
Expand All @@ -336,6 +464,9 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
switch (mask) {
case IIO_CHAN_INFO_PROCESSED:
switch (chan->type) {
case IIO_HUMIDITYRELATIVE:
ret = data->chip_info->read_humid(data, val, val2);
break;
case IIO_PRESSURE:
ret = data->chip_info->read_press(data, val, val2);
break;
Expand All @@ -349,6 +480,10 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
break;
case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
switch (chan->type) {
case IIO_HUMIDITYRELATIVE:
*val = 1 << data->oversampling_humid;
ret = IIO_VAL_INT;
break;
case IIO_PRESSURE:
*val = 1 << data->oversampling_press;
ret = IIO_VAL_INT;
Expand All @@ -372,6 +507,23 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
return ret;
}

static int bmp280_write_oversampling_ratio_humid(struct bmp280_data *data,
int val)
{
int i;
const int *avail = data->chip_info->oversampling_humid_avail;
const int n = data->chip_info->num_oversampling_humid_avail;

for (i = 0; i < n; i++) {
if (avail[i] == val) {
data->oversampling_humid = ilog2(val);

return data->chip_info->chip_config(data);
}
}
return -EINVAL;
}

static int bmp280_write_oversampling_ratio_temp(struct bmp280_data *data,
int val)
{
Expand Down Expand Up @@ -417,6 +569,9 @@ static int bmp280_write_raw(struct iio_dev *indio_dev,
case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
mutex_lock(&data->lock);
switch (chan->type) {
case IIO_HUMIDITYRELATIVE:
ret = bmp280_write_oversampling_ratio_humid(data, val);
break;
case IIO_PRESSURE:
ret = bmp280_write_oversampling_ratio_press(data, val);
break;
Expand Down Expand Up @@ -535,6 +690,37 @@ static const struct bmp280_chip_info bmp280_chip_info = {
.read_press = bmp280_read_press,
};

static int bme280_chip_config(struct bmp280_data *data)
{
int ret = bmp280_chip_config(data);
u8 osrs = BMP280_OSRS_HUMIDITIY_X(data->oversampling_humid + 1);

if (ret < 0)
return ret;

return regmap_update_bits(data->regmap, BMP280_REG_CTRL_HUMIDITY,
BMP280_OSRS_HUMIDITY_MASK, osrs);
}

static const struct bmp280_chip_info bme280_chip_info = {
.regmap_config = &bmp280_regmap_config,

.oversampling_temp_avail = bmp280_oversampling_avail,
.num_oversampling_temp_avail = ARRAY_SIZE(bmp280_oversampling_avail),

.oversampling_press_avail = bmp280_oversampling_avail,
.num_oversampling_press_avail = ARRAY_SIZE(bmp280_oversampling_avail),

.oversampling_humid_avail = bmp280_oversampling_avail,
.num_oversampling_humid_avail = ARRAY_SIZE(bmp280_oversampling_avail),

.chip_config = bme280_chip_config,
.read_temp = bmp280_read_temp,
.read_press = bmp280_read_press,
.read_humid = bmp280_read_humid,
};


static bool bmp180_is_writeable_reg(struct device *dev, unsigned int reg)
{
switch (reg) {
Expand Down Expand Up @@ -849,21 +1035,29 @@ static int bmp280_probe(struct i2c_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;

switch (id->driver_data) {
case BMP180_CHIP_ID:
indio_dev->num_channels = 2;
data->chip_info = &bmp180_chip_info;
data->oversampling_press = ilog2(8);
data->oversampling_temp = ilog2(1);
break;
case BMP280_CHIP_ID:
indio_dev->num_channels = 2;
data->chip_info = &bmp280_chip_info;
data->oversampling_press = ilog2(16);
data->oversampling_temp = ilog2(2);
break;
case BME280_CHIP_ID:
indio_dev->num_channels = 3;
data->chip_info = &bme280_chip_info;
data->oversampling_press = ilog2(16);
data->oversampling_humid = ilog2(16);
data->oversampling_temp = ilog2(2);
break;
default:
return -EINVAL;
}
Expand Down Expand Up @@ -895,6 +1089,7 @@ static const struct acpi_device_id bmp280_acpi_match[] = {
{"BMP0280", BMP280_CHIP_ID },
{"BMP0180", BMP180_CHIP_ID },
{"BMP0085", BMP180_CHIP_ID },
{"BME0280", BME280_CHIP_ID },
{ },
};
MODULE_DEVICE_TABLE(acpi, bmp280_acpi_match);
Expand All @@ -903,6 +1098,7 @@ static const struct i2c_device_id bmp280_id[] = {
{"bmp280", BMP280_CHIP_ID },
{"bmp180", BMP180_CHIP_ID },
{"bmp085", BMP180_CHIP_ID },
{"bme280", BME280_CHIP_ID },
{ },
};
MODULE_DEVICE_TABLE(i2c, bmp280_id);
Expand Down

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