[PATCH v1 13/13] iio: chemical: bme680: Add support for preheat current

vamoirid
2024-10-10T21:00:57Z

From: Vasileios Amoiridis <vassilisamir@gmail.com>

Add functionality to inject a specified amount of current to the heating
plate before the start of the gas measurement to allow the sensor to reach
faster to the requested temperature.

Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
---
drivers/iio/chemical/bme680.h | 1 +
drivers/iio/chemical/bme680_core.c | 38 ++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+)

diff --git a/drivers/iio/chemical/bme680.h b/drivers/iio/chemical/bme680.h
index e7eed2962baa..c658cb631b52 100644
--- a/drivers/iio/chemical/bme680.h
+++ b/drivers/iio/chemical/bme680.h
@@ -42,6 +42,7 @@
#define BME680_RHRANGE_MASK GENMASK(5, 4)
#define BME680_REG_RES_HEAT_VAL 0x00
#define BME680_RSERROR_MASK GENMASK(7, 4)
+#define BME680_REG_IDAC_HEAT_0 0x50
#define BME680_REG_RES_HEAT_0 0x5A
#define BME680_REG_GAS_WAIT_0 0x64
#define BME680_ADC_GAS_RES GENMASK(15, 6)
diff --git a/drivers/iio/chemical/bme680_core.c b/drivers/iio/chemical/bme680_core.c
index df6ae4355902..6cdf8b9dbf2b 100644
--- a/drivers/iio/chemical/bme680_core.c
+++ b/drivers/iio/chemical/bme680_core.c
@@ -126,6 +126,7 @@ struct bme680_data {
u8 oversampling_temp;
u8 oversampling_press;
u8 oversampling_humid;
+ u8 preheat_curr;
u16 heater_dur;
u16 heater_temp;

@@ -223,6 +224,12 @@ static const struct iio_chan_spec bme680_channels[] = {
},
},
IIO_CHAN_SOFT_TIMESTAMP(4),
+ {
+ .type = IIO_CURRENT,
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+ .output = 1,
+ .scan_index = 5,
+ },
};

static int bme680_read_calib(struct bme680_data *data,
@@ -569,6 +576,12 @@ static u8 bme680_calc_heater_dur(u16 dur)
return durval;
}

+/* Taken from datasheet, section 5.3.3 */
+static u8 bme680_calc_heater_preheat_current(u8 curr)
+{
+ return 8 * curr - 1;
+}
+
static int bme680_set_mode(struct bme680_data *data, enum bme680_op_mode mode)
{
struct device *dev = regmap_get_device(data->regmap);
@@ -673,6 +686,19 @@ static int bme680_chip_config(struct bme680_data *data)
return 0;
}

+static int bme680_preheat_curr_config(struct bme680_data *data, u8 val)
+{
+ u8 heatr_curr;
+ int ret;
+
+ heatr_curr = bme680_calc_heater_preheat_current(val);
+ ret = regmap_write(data->regmap, BME680_REG_IDAC_HEAT_0, heatr_curr);
+ if (ret < 0)
+ dev_err(data->dev, "failed to write idac_heat_0 register\n");
+
+ return ret;
+}
+
static int bme680_gas_config(struct bme680_data *data)
{
struct device *dev = regmap_get_device(data->regmap);
@@ -701,6 +727,10 @@ static int bme680_gas_config(struct bme680_data *data)
return ret;
}

+ ret = bme680_preheat_curr_config(data, data->preheat_curr);
+ if (ret)
+ return ret;
+
/* Enable the gas sensor and select heater profile set-point 0 */
ret = regmap_update_bits(data->regmap, BME680_REG_CTRL_GAS_1,
BME680_RUN_GAS_MASK | BME680_NB_CONV_MASK,
@@ -967,6 +997,13 @@ static int __bme680_write_raw(struct iio_dev *indio_dev,

return bme680_chip_config(data);
}
+ case IIO_CHAN_INFO_RAW:
+ {
+ if (chan->type != IIO_CURRENT)
+ return -EINVAL;
+
+ return bme680_preheat_curr_config(data, (u8)val);
+ }
default:
return -EINVAL;
}
@@ -1199,6 +1236,7 @@ int bme680_core_probe(struct device *dev, struct regmap *regmap,
data->oversampling_temp = 8; /* 8X oversampling rate */
data->heater_temp = 320; /* degree Celsius */
data->heater_dur = 150; /* milliseconds */
+ data->preheat_curr = 0; /* milliamps */

regulator_bulk_set_supply_names(data->supplies, bme680_supply_names,
BME680_NUM_SUPPLIES);
--
2.43.0