Enable humidity support for the BME280 part
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;
--
1.9.1
--
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