iio: pressure: bmp280: Add support for BMP380 sensor family

Adds compatibility with the new generation of this sensor, the BMP380.

Includes basic sensor initialization to do pressure and temp
measurements and allows tuning oversampling settings for each channel.

The compensation algorithms are adapted from the device datasheet and
the repository https://github.com/BoschSensortec/BMP3-Sensor-API.

Signed-off-by: Angel Iglesias <ang.iglesiasg@gmail.com>
Link: https://lore.kernel.org/r/f1da2a2f1bc5bb083f318335c23b4f3d9bb8e536.1663025017.git.ang.iglesiasg@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 386 insertions, 0 deletions

diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index 035a29871b7a..962f5d428257 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -12,6 +12,7 @@
  * https://cdn-shop.adafruit.com/datasheets/BST-BMP180-DS000-09.pdf
  * https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bmp280-ds001.pdf
  * https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bme280-ds002.pdf
+ * https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bmp388-ds001.pdf
  *
  * Notice:
  * The link to the bmp180 datasheet points to an outdated version missing these changes:
@@ -84,6 +85,24 @@ struct bmp280_calib {
 	s8  H6;
 };
 
+/* See datasheet Section 3.11.1. */
+struct bmp380_calib {
+	u16 T1;
+	u16 T2;
+	s8  T3;
+	s16 P1;
+	s16 P2;
+	s8  P3;
+	s8  P4;
+	u16 P5;
+	u16 P6;
+	s8  P7;
+	s8  P8;
+	s16 P9;
+	s8  P10;
+	s8  P11;
+};
+
 static const char *const bmp280_supply_names[] = {
 	"vddd", "vdda"
 };
@@ -100,6 +119,7 @@ struct bmp280_data {
 	union {
 		struct bmp180_calib bmp180;
 		struct bmp280_calib bmp280;
+		struct bmp380_calib bmp380;
 	} calib;
 	struct regulator_bulk_data supplies[BMP280_NUM_SUPPLIES];
 	unsigned int start_up_time; /* in microseconds */
@@ -125,6 +145,7 @@ struct bmp280_data {
 		/* Calibration data buffers */
 		__le16 bmp280_cal_buf[BMP280_CONTIGUOUS_CALIB_REGS / 2];
 		__be16 bmp180_cal_buf[BMP180_REG_CALIB_COUNT / 2];
+		u8 bmp380_cal_buf[BMP380_CALIB_REG_COUNT];
 		/* Miscellaneous, endianess-aware data buffers */
 		__le16 le16;
 		__be16 be16;
@@ -162,6 +183,25 @@ struct bmp280_chip_info {
  */
 enum { T1, T2, T3, P1, P2, P3, P4, P5, P6, P7, P8, P9 };
 
+enum {
+	/* Temperature calib indexes */
+	BMP380_T1 = 0,
+	BMP380_T2 = 2,
+	BMP380_T3 = 4,
+	/* Pressure calib indexes */
+	BMP380_P1 = 5,
+	BMP380_P2 = 7,
+	BMP380_P3 = 9,
+	BMP380_P4 = 10,
+	BMP380_P5 = 11,
+	BMP380_P6 = 13,
+	BMP380_P7 = 15,
+	BMP380_P8 = 16,
+	BMP380_P9 = 17,
+	BMP380_P10 = 19,
+	BMP380_P11 = 20,
+};
+
 static const struct iio_chan_spec bmp280_channels[] = {
 	{
 		.type = IIO_PRESSURE,
@@ -745,6 +785,342 @@ static const struct bmp280_chip_info bme280_chip_info = {
 	.read_calib = bme280_read_calib,
 };
 
+/*
+ * Helper function to send a command to BMP3XX sensors.
+ *
+ * Sensor processes commands written to the CMD register and signals
+ * execution result through "cmd_rdy" and "cmd_error" flags available on
+ * STATUS and ERROR registers.
+ */
+static int bmp380_cmd(struct bmp280_data *data, u8 cmd)
+{
+	unsigned int reg;
+	int ret;
+
+	/* Check if device is ready to process a command */
+	ret = regmap_read(data->regmap, BMP380_REG_STATUS, &reg);
+	if (ret) {
+		dev_err(data->dev, "failed to read error register\n");
+		return ret;
+	}
+	if (!(reg & BMP380_STATUS_CMD_RDY_MASK)) {
+		dev_err(data->dev, "device is not ready to accept commands\n");
+		return -EBUSY;
+	}
+
+	/* Send command to process */
+	ret = regmap_write(data->regmap, BMP380_REG_CMD, cmd);
+	if (ret) {
+		dev_err(data->dev, "failed to send command to device\n");
+		return ret;
+	}
+	/* Wait for 2ms for command to be processed */
+	usleep_range(data->start_up_time, data->start_up_time + 100);
+	/* Check for command processing error */
+	ret = regmap_read(data->regmap, BMP380_REG_ERROR, &reg);
+	if (ret) {
+		dev_err(data->dev, "error reading ERROR reg\n");
+		return ret;
+	}
+	if (reg & BMP380_ERR_CMD_MASK) {
+		dev_err(data->dev, "error processing command 0x%X\n", cmd);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Returns temperature in Celsius dregrees, resolution is 0.01º C. Output value of
+ * "5123" equals 51.2º C. t_fine carries fine temperature as global value.
+ *
+ * Taken from datasheet, Section Appendix 9, "Compensation formula" and repo
+ * https://github.com/BoschSensortec/BMP3-Sensor-API.
+ */
+static s32 bmp380_compensate_temp(struct bmp280_data *data, u32 adc_temp)
+{
+	s64 var1, var2, var3, var4, var5, var6, comp_temp;
+	struct bmp380_calib *calib = &data->calib.bmp380;
+
+	var1 = ((s64) adc_temp) - (((s64) calib->T1) << 8);
+	var2 = var1 * ((s64) calib->T2);
+	var3 = var1 * var1;
+	var4 = var3 * ((s64) calib->T3);
+	var5 = (var2 << 18) + var4;
+	var6 = var5 >> 32;
+	data->t_fine = (s32) var6;
+	comp_temp = (var6 * 25) >> 14;
+
+	comp_temp = clamp_val(comp_temp, BMP380_MIN_TEMP, BMP380_MAX_TEMP);
+	return (s32) comp_temp;
+}
+
+/*
+ * Returns pressure in Pa as an unsigned 32 bit integer in fractional Pascal.
+ * Output value of "9528709" represents 9528709/100 = 95287.09 Pa = 952.8709 hPa.
+ *
+ * Taken from datasheet, Section 9.3. "Pressure compensation" and repository
+ * https://github.com/BoschSensortec/BMP3-Sensor-API.
+ */
+static u32 bmp380_compensate_press(struct bmp280_data *data, u32 adc_press)
+{
+	s64 var1, var2, var3, var4, var5, var6, offset, sensitivity;
+	struct bmp380_calib *calib = &data->calib.bmp380;
+	u32 comp_press;
+
+	var1 = (s64)data->t_fine * (s64)data->t_fine;
+	var2 = var1 >> 6;
+	var3 = (var2 * ((s64) data->t_fine)) >> 8;
+	var4 = ((s64)calib->P8 * var3) >> 5;
+	var5 = ((s64)calib->P7 * var1) << 4;
+	var6 = ((s64)calib->P6 * (s64)data->t_fine) << 22;
+	offset = ((s64)calib->P5 << 47) + var4 + var5 + var6;
+	var2 = ((s64)calib->P4 * var3) >> 5;
+	var4 = ((s64)calib->P3 * var1) << 2;
+	var5 = ((s64)calib->P2 - ((s64)1 << 14)) *
+	       ((s64)data->t_fine << 21);
+	sensitivity = (((s64) calib->P1 - ((s64) 1 << 14)) << 46) +
+			var2 + var4 + var5;
+	var1 = (sensitivity >> 24) * (s64)adc_press;
+	var2 = (s64)calib->P10 * (s64)data->t_fine;
+	var3 = var2 + ((s64)calib->P9 << 16);
+	var4 = (var3 * (s64)adc_press) >> 13;
+
+	/*
+	 * Dividing by 10 followed by multiplying by 10 to avoid
+	 * possible overflow caused by (uncomp_data->pressure * partial_data4).
+	 */
+	var5 = ((s64)adc_press * div_s64(var4, 10)) >> 9;
+	var5 *= 10;
+	var6 = (s64)adc_press * (s64)adc_press;
+	var2 = ((s64)calib->P11 * var6) >> 16;
+	var3 = (var2 * (s64)adc_press) >> 7;
+	var4 = (offset >> 2) + var1 + var5 + var3;
+	comp_press = ((u64)var4 * 25) >> 40;
+
+	comp_press = clamp_val(comp_press, BMP380_MIN_PRES, BMP380_MAX_PRES);
+	return comp_press;
+}
+
+static int bmp380_read_temp(struct bmp280_data *data, int *val)
+{
+	s32 comp_temp;
+	u32 adc_temp;
+	int ret;
+
+	ret = regmap_bulk_read(data->regmap, BMP380_REG_TEMP_XLSB,
+			       data->buf, sizeof(data->buf));
+	if (ret) {
+		dev_err(data->dev, "failed to read temperature\n");
+		return ret;
+	}
+
+	adc_temp = get_unaligned_le24(data->buf);
+	if (adc_temp == BMP380_TEMP_SKIPPED) {
+		dev_err(data->dev, "reading temperature skipped\n");
+		return -EIO;
+	}
+	comp_temp = bmp380_compensate_temp(data, adc_temp);
+
+	/*
+	 * Val might be NULL if we're called by the read_press routine,
+	 * who only cares about the carry over t_fine value.
+	 */
+	if (val) {
+		/* IIO reports temperatures in milli Celsius */
+		*val = comp_temp * 10;
+		return IIO_VAL_INT;
+	}
+
+	return 0;
+}
+
+static int bmp380_read_press(struct bmp280_data *data, int *val, int *val2)
+{
+	s32 comp_press;
+	u32 adc_press;
+	int ret;
+
+	/* Read and compensate for temperature so we get a reading of t_fine */
+	ret = bmp380_read_temp(data, NULL);
+	if (ret)
+		return ret;
+
+	ret = regmap_bulk_read(data->regmap, BMP380_REG_PRESS_XLSB,
+			       data->buf, sizeof(data->buf));
+	if (ret) {
+		dev_err(data->dev, "failed to read pressure\n");
+		return ret;
+	}
+
+	adc_press = get_unaligned_le24(data->buf);
+	if (adc_press == BMP380_PRESS_SKIPPED) {
+		dev_err(data->dev, "reading pressure skipped\n");
+		return -EIO;
+	}
+	comp_press = bmp380_compensate_press(data, adc_press);
+
+	*val = comp_press;
+	/* Compensated pressure is in cPa (centipascals) */
+	*val2 = 100000;
+
+	return IIO_VAL_FRACTIONAL;
+}
+
+static int bmp380_read_calib(struct bmp280_data *data)
+{
+	struct bmp380_calib *calib = &data->calib.bmp380;
+	int ret;
+
+	/* Read temperature and pressure calibration data */
+	ret = regmap_bulk_read(data->regmap, BMP380_REG_CALIB_TEMP_START,
+			       data->bmp380_cal_buf, sizeof(data->bmp380_cal_buf));
+	if (ret) {
+		dev_err(data->dev,
+			"failed to read temperature calibration parameters\n");
+		return ret;
+	}
+
+	/* Toss the temperature calibration data into the entropy pool */
+	add_device_randomness(data->bmp380_cal_buf, sizeof(data->bmp380_cal_buf));
+
+	/* Parse calibration values */
+	calib->T1 = get_unaligned_le16(&data->bmp380_cal_buf[BMP380_T1]);
+	calib->T2 = get_unaligned_le16(&data->bmp380_cal_buf[BMP380_T2]);
+	calib->T3 = data->bmp380_cal_buf[BMP380_T3];
+	calib->P1 = get_unaligned_le16(&data->bmp380_cal_buf[BMP380_P1]);
+	calib->P2 = get_unaligned_le16(&data->bmp380_cal_buf[BMP380_P2]);
+	calib->P3 = data->bmp380_cal_buf[BMP380_P3];
+	calib->P4 = data->bmp380_cal_buf[BMP380_P4];
+	calib->P5 = get_unaligned_le16(&data->bmp380_cal_buf[BMP380_P5]);
+	calib->P6 = get_unaligned_le16(&data->bmp380_cal_buf[BMP380_P6]);
+	calib->P7 = data->bmp380_cal_buf[BMP380_P7];
+	calib->P8 = data->bmp380_cal_buf[BMP380_P8];
+	calib->P9 = get_unaligned_le16(&data->bmp380_cal_buf[BMP380_P9]);
+	calib->P10 = data->bmp380_cal_buf[BMP380_P10];
+	calib->P11 = data->bmp380_cal_buf[BMP380_P11];
+
+	return 0;
+}
+
+static int bmp380_chip_config(struct bmp280_data *data)
+{
+	bool change = false, aux;
+	unsigned int tmp;
+	u8 osrs;
+	int ret;
+
+	/* Configure power control register */
+	ret = regmap_update_bits(data->regmap, BMP380_REG_POWER_CONTROL,
+				 BMP380_CTRL_SENSORS_MASK,
+				 BMP380_CTRL_SENSORS_PRESS_EN |
+				 BMP380_CTRL_SENSORS_TEMP_EN);
+	if (ret) {
+		dev_err(data->dev,
+			"failed to write operation control register\n");
+		return ret;
+	}
+
+	/* Configure oversampling */
+	osrs = FIELD_PREP(BMP380_OSRS_TEMP_MASK, data->oversampling_temp) |
+	       FIELD_PREP(BMP380_OSRS_PRESS_MASK, data->oversampling_press);
+
+	ret = regmap_update_bits_check(data->regmap, BMP380_REG_OSR,
+				       BMP380_OSRS_TEMP_MASK |
+				       BMP380_OSRS_PRESS_MASK,
+				       osrs, &aux);
+	if (ret) {
+		dev_err(data->dev, "failed to write oversampling register\n");
+		return ret;
+	}
+	change = change || aux;
+
+	/* Configure output data rate */
+	ret = regmap_update_bits(data->regmap, BMP380_REG_ODR,
+				 BMP380_ODRS_MASK, BMP380_ODRS_50HZ);
+	if (ret) {
+		dev_err(data->dev, "failed to write ODR selection register\n");
+		return ret;
+	}
+
+	/* Set filter data */
+	ret = regmap_update_bits(data->regmap, BMP380_REG_CONFIG,
+				 BMP380_FILTER_MASK,
+				 FIELD_PREP(BMP380_FILTER_MASK, BMP380_FILTER_3X));
+	if (ret) {
+		dev_err(data->dev, "failed to write config register\n");
+		return ret;
+	}
+
+	if (change) {
+		/*
+		 * The configurations errors are detected on the fly during a measurement
+		 * cycle. If the sampling frequency is too low, it's faster to reset
+		 * the measurement loop than wait until the next measurement is due.
+		 *
+		 * Resets sensor measurement loop toggling between sleep and normal
+		 * operating modes.
+		 */
+		ret = regmap_write_bits(data->regmap, BMP380_REG_POWER_CONTROL,
+					BMP380_MODE_MASK,
+					FIELD_PREP(BMP380_MODE_MASK, BMP380_MODE_SLEEP));
+		if (ret) {
+			dev_err(data->dev, "failed to set sleep mode\n");
+			return ret;
+		}
+		usleep_range(2000, 2500);
+		ret = regmap_write_bits(data->regmap, BMP380_REG_POWER_CONTROL,
+					BMP380_MODE_MASK,
+					FIELD_PREP(BMP380_MODE_MASK, BMP380_MODE_NORMAL));
+		if (ret) {
+			dev_err(data->dev, "failed to set normal mode\n");
+			return ret;
+		}
+		/*
+		 * Waits for measurement before checking configuration error flag.
+		 * Selected longest measure time indicated in section 3.9.1
+		 * in the datasheet.
+		 */
+		msleep(80);
+
+		/* Check config error flag */
+		ret = regmap_read(data->regmap, BMP380_REG_ERROR, &tmp);
+		if (ret) {
+			dev_err(data->dev,
+				"failed to read error register\n");
+			return ret;
+		}
+		if (tmp & BMP380_ERR_CONF_MASK) {
+			dev_warn(data->dev,
+				"sensor flagged configuration as incompatible\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static const int bmp380_oversampling_avail[] = { 1, 2, 4, 8, 16, 32 };
+
+static const struct bmp280_chip_info bmp380_chip_info = {
+	.id_reg = BMP380_REG_ID,
+	.start_up_time = 2000,
+	.num_channels = 2,
+
+	.oversampling_temp_avail = bmp380_oversampling_avail,
+	.num_oversampling_temp_avail = ARRAY_SIZE(bmp380_oversampling_avail),
+	.oversampling_temp_default = ilog2(1),
+
+	.oversampling_press_avail = bmp380_oversampling_avail,
+	.num_oversampling_press_avail = ARRAY_SIZE(bmp380_oversampling_avail),
+	.oversampling_press_default = ilog2(4),
+
+	.chip_config = bmp380_chip_config,
+	.read_temp = bmp380_read_temp,
+	.read_press = bmp380_read_press,
+	.read_calib = bmp380_read_calib,
+};
+
 static int bmp180_measure(struct bmp280_data *data, u8 ctrl_meas)
 {
 	const int conversion_time_max[] = { 4500, 7500, 13500, 25500 };
@@ -1092,6 +1468,9 @@ int bmp280_common_probe(struct device *dev,
 	case BME280_CHIP_ID:
 		chip_info = &bme280_chip_info;
 		break;
+	case BMP380_CHIP_ID:
+		chip_info = &bmp380_chip_info;
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -1149,6 +1528,13 @@ int bmp280_common_probe(struct device *dev,
 		return -EINVAL;
 	}
 
+	/* BMP3xx requires soft-reset as part of initialization */
+	if (chip_id == BMP380_CHIP_ID) {
+		ret = bmp380_cmd(data, BMP380_CMD_SOFT_RESET);
+		if (ret < 0)
+			return ret;
+	}
+
 	ret = data->chip_info->chip_config(data);
 	if (ret < 0)
 		return ret;