On Mon, Apr 11, 2016 at 10:21 PM, Peter Meerwald-Stadler
<pmeerw@xxxxxxxxxx> wrote:
>
>> 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)?
>
Yeah didn't notice that till now.. and went back to BME280 datasheet
and that appears to be the case.
If you look at bmp280_compensate_temp and bmp280_compensate_press it
does the same exact thing...
>> 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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