linux-kernel - [PATCH v1 14/17] iio: chemical: bme680: Modify startup procedure

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Date: Mon, 27 May 2024 20:38:02 +0200
From: Vasileios Amoiridis <vassilisamir@...il.com>
To: jic23@...nel.org,
	lars@...afoo.de
Cc: himanshujha199640@...il.com,
	linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Vasileios Amoiridis <vassilisamir@...il.com>
Subject: [PATCH v1 14/17] iio: chemical: bme680: Modify startup procedure

Modify the startup procedure to reflect the procedure of
the Bosch BME68x Sensor API. The initial readings and
configuration of the sensor need to happen in the
following order:

1) Read calibration data [1,2]
2) Chip general configuration [3]
3) Gas configuration [4]

After the chip configuration it is necessary to ensure that
the sensor is in sleeping mode, in order to apply the gas
configuration settings [5].

Also, after the soft reset, it is advised to wait for 5ms [6].

[1]: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/bme68x.c#L162
[2]: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/examples/forced_mode/forced_mode.c#L44
[3]: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/examples/forced_mode/forced_mode.c#L53
[4]: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/examples/forced_mode/forced_mode.c#L60
[5]: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/bme68x.c#L640
[6]: https://github.com/boschsensortec/BME68x_SensorAPI/blob/v4.4.8/bme68x.c#L294
Signed-off-by: Vasileios Amoiridis <vassilisamir@...il.com>
---
 drivers/iio/chemical/bme680.h      |  2 ++
 drivers/iio/chemical/bme680_core.c | 27 ++++++++++++++++++---------
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/chemical/bme680.h b/drivers/iio/chemical/bme680.h
index 17ea59253923..3be2f76a5bfb 100644
--- a/drivers/iio/chemical/bme680.h
+++ b/drivers/iio/chemical/bme680.h
@@ -61,6 +61,8 @@
 
 #define BME680_MEAS_TRIM_MASK			GENMASK(24, 4)
 
+#define BME680_STARTUP_TIME_US			5000
+
 /* Calibration Parameters */
 #define BME680_T2_LSB_REG	0x8A
 #define BME680_H2_MSB_REG	0xE1
diff --git a/drivers/iio/chemical/bme680_core.c b/drivers/iio/chemical/bme680_core.c
index b055eeee8f1c..afaa43ec3241 100644
--- a/drivers/iio/chemical/bme680_core.c
+++ b/drivers/iio/chemical/bme680_core.c
@@ -505,10 +505,12 @@ static int bme680_chip_config(struct bme680_data *data)
 	ret = regmap_write_bits(data->regmap, BME680_REG_CTRL_MEAS,
 				BME680_OSRS_TEMP_MASK | BME680_OSRS_PRESS_MASK,
 				osrs);
-	if (ret < 0)
+	if (ret < 0) {
 		dev_err(dev, "failed to write ctrl_meas register\n");
+		return ret;
+	}
 
-	return ret;
+	return 0;
 }
 
 static int bme680_gas_config(struct bme680_data *data)
@@ -517,6 +519,11 @@ static int bme680_gas_config(struct bme680_data *data)
 	int ret;
 	u8 heatr_res, heatr_dur;
 
+	/* Go to sleep */
+	ret = bme680_set_mode(data, false);
+	if (ret < 0)
+		return ret;
+
 	heatr_res = bme680_calc_heater_res(data, data->heater_temp);
 
 	/* set target heater temperature */
@@ -847,6 +854,8 @@ int bme680_core_probe(struct device *dev, struct regmap *regmap,
 		return ret;
 	}
 
+	usleep_range(BME680_STARTUP_TIME_US, BME680_STARTUP_TIME_US + 1000);
+
 	ret = regmap_read(regmap, BME680_REG_CHIP_ID, &data->check);
 	if (ret < 0) {
 		dev_err(dev, "Error reading chip ID\n");
@@ -859,22 +868,22 @@ int bme680_core_probe(struct device *dev, struct regmap *regmap,
 		return -ENODEV;
 	}
 
-	ret = bme680_chip_config(data);
+	ret = bme680_read_calib(data, &data->bme680);
 	if (ret < 0) {
-		dev_err(dev, "failed to set chip_config data\n");
+		dev_err(dev,
+			"failed to read calibration coefficients at probe\n");
 		return ret;
 	}
 
-	ret = bme680_gas_config(data);
+	ret = bme680_chip_config(data);
 	if (ret < 0) {
-		dev_err(dev, "failed to set gas config data\n");
+		dev_err(dev, "failed to set chip_config data\n");
 		return ret;
 	}
 
-	ret = bme680_read_calib(data, &data->bme680);
+	ret = bme680_gas_config(data);
 	if (ret < 0) {
-		dev_err(dev,
-			"failed to read calibration coefficients at probe\n");
+		dev_err(dev, "failed to set gas config data\n");
 		return ret;
 	}
 
-- 
2.25.1