> Enable humidity support for the BME280 part
this also changes unrelated comments referring to datasheets
does this chip really use both, LE (in _compensate_humidity) and BE in
(read_humidity)?
> Signed-off-by: Matt Ranostay <matt.ranostay@xxxxxxxxx>
> ---
> drivers/iio/pressure/bmp280.c | 137 ++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 133 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iio/pressure/bmp280.c b/drivers/iio/pressure/bmp280.c
> index e80cbf3b21fc..9e3a9f00cd84 100644
> --- a/drivers/iio/pressure/bmp280.c
> +++ b/drivers/iio/pressure/bmp280.c
> @@ -18,6 +18,8 @@
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
>
> +#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
> @@ -26,11 +28,20 @@
> #define BMP280_REG_PRESS_MSB 0xF7
>
> #define BMP280_REG_CONFIG 0xF5
> +#define BMP280_REG_CTRL_HUMIDITY 0xF2
> #define BMP280_REG_CTRL_MEAS 0xF4
> #define BMP280_REG_STATUS 0xF3
> #define BMP280_REG_RESET 0xE0
> #define BMP280_REG_ID 0xD0
>
> +/* 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
>
> @@ -44,6 +55,14 @@
> #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_HUMIDITY_SKIP 0
> +#define BMP280_OSRS_HUMIDITY_1X BIT(0)
> +#define BMP280_OSRS_HUMIDITY_2X BIT(1)
> +#define BMP280_OSRS_HUMIDITY_4X (BIT(1) | BIT(0))
> +#define BMP280_OSRS_HUMIDITY_8X BIT(2)
> +#define BMP280_OSRS_HUMIDITY_16X (BIT(2) | BIT(0))
> +
> #define BMP280_OSRS_TEMP_MASK (BIT(7) | BIT(6) | BIT(5))
> #define BMP280_OSRS_TEMP_SKIP 0
> #define BMP280_OSRS_TEMP_1X BIT(5)
> @@ -93,6 +112,13 @@ struct bmp280_chip_info {
> int (*init)(struct bmp280_data *);
> };
>
> +static int bme280_chip_init(struct bmp280_data *data)
> +{
> + return regmap_update_bits(data->regmap, BMP280_REG_CTRL_HUMIDITY,
> + BMP280_OSRS_HUMIDITY_MASK,
> + BMP280_OSRS_HUMIDITY_16X);
> +}
> +
> static struct bmp280_chip_info bmp280_chip_info_table[] = {
> [bmp280] = {
> .id = BMP280_CHIP_ID,
> @@ -100,7 +126,8 @@ static struct bmp280_chip_info bmp280_chip_info_table[] = {
> },
> [bme280] = {
> .id = BME280_CHIP_ID,
> - .num_channels = 2,
> + .num_channels = 3,
> + .init = bme280_chip_init,
> },
> };
>
> @@ -120,12 +147,17 @@ static const struct iio_chan_spec bmp280_channels[] = {
> .type = IIO_TEMP,
> .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> },
> + {
> + .type = IIO_HUMIDITYRELATIVE,
> + .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_HUMIDITY:
> case BMP280_REG_CTRL_MEAS:
> case BMP280_REG_RESET:
> return true;
> @@ -137,6 +169,8 @@ 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:
> @@ -154,7 +188,7 @@ 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,
> @@ -162,11 +196,74 @@ static const struct regmap_config bmp280_regmap_config = {
> };
>
> /*
> + * 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(le16_to_cpu(tmp) >> 4 | (le16_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) & 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
> * value.
> *
> - * Taken from datasheet, Section 3.11.3, "Compensation formula".
> + * Taken from BMP280 datasheet, Section 3.11.3, "Compensation formula".
> */
> static s32 bmp280_compensate_temp(struct bmp280_data *data,
> s32 adc_temp)
> @@ -206,7 +303,7 @@ static s32 bmp280_compensate_temp(struct bmp280_data *data,
> * 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".
> + * Taken from BMP280 datasheet, Section 3.11.3, "Compensation formula".
> */
> static u32 bmp280_compensate_press(struct bmp280_data *data,
> s32 adc_press)
> @@ -301,6 +398,35 @@ static int bmp280_read_press(struct bmp280_data *data,
> return IIO_VAL_FRACTIONAL;
> }
>
> +static int bmp280_read_humidity(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_PRESS_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)
> @@ -313,6 +439,9 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
> switch (mask) {
> case IIO_CHAN_INFO_PROCESSED:
> switch (chan->type) {
> + case IIO_HUMIDITYRELATIVE:
> + ret = bmp280_read_humidity(data, val, val2);
> + break;
> case IIO_PRESSURE:
> ret = bmp280_read_press(data, val, val2);
> break;
>
--
Peter Meerwald-Stadler
+43-664-2444418 (mobile)
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