Enable humidity support for the BME280 part Signed-off-by: Matt Ranostay <matt.ranostay@xxxxxxxxx> --- changes from v1: * rework to use new multiple chip selection method * fix issue with humidity coefficients being off by one * fixed incorrect shifted coefficients * added oversampling configuration for humidity drivers/iio/pressure/bmp280.c | 200 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 198 insertions(+), 2 deletions(-) diff --git a/drivers/iio/pressure/bmp280.c b/drivers/iio/pressure/bmp280.c index 2f1498e..1876b50 100644 --- a/drivers/iio/pressure/bmp280.c +++ b/drivers/iio/pressure/bmp280.c @@ -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 @@ -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 @@ -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 @@ -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) @@ -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 { @@ -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 @@ -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 *); }; /* @@ -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; @@ -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: @@ -177,7 +213,7 @@ 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, @@ -185,6 +221,70 @@ 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(((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 * value. @@ -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) @@ -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; @@ -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; @@ -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) { @@ -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; @@ -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) { @@ -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; } @@ -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); @@ -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); -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
