iio: pressure: bmp280: add humidity support

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>

diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index cda9f128f3a4ec66736250121d374683d3a713bb..9125a9382b3e76ab0623b40bee5b21001d76b712 100644 (file)
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -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.

diff --git a/drivers/iio/pressure/bmp280.c b/drivers/iio/pressure/bmp280.c
index 2f1498e12bb28978ca8bea9356bfac9338b407fe..1876b50cc84ae44b57a7db75de54b0028330faa1 100644 (file)
--- 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:
@@ -177,13 +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
@@ -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);