linux-kernel - Re: [PATCH v3 2/7] iio: pressure: bmp280: Add support for bmp280 soft reset

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Message-ID: <b898ad42-1559-4f43-8994-d9692e54f930@wanadoo.fr>
Date: Sun, 25 Aug 2024 09:04:16 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: vassilisamir@...il.com
Cc: 579lpy@...il.com, ak@...klinger.de, andriy.shevchenko@...ux.intel.com,
 ang.iglesiasg@...il.com, biju.das.jz@...renesas.com, conor+dt@...nel.org,
 devicetree@...r.kernel.org, javier.carrasco.cruz@...il.com,
 jic23@...nel.org, krzk+dt@...nel.org, lars@...afoo.de,
 linus.walleij@...aro.org, linux-iio@...r.kernel.org,
 linux-kernel@...r.kernel.org, robh@...nel.org, semen.protsenko@...aro.org
Subject: Re: [PATCH v3 2/7] iio: pressure: bmp280: Add support for bmp280 soft
 reset

Le 23/08/2024 à 20:17, Vasileios Amoiridis a écrit :
> The BM(P/E)28x devices have an option for soft reset which is also
> recommended by the Bosch Sensortech BME2 Sensor API to be used before the
> initial configuration of the device.
> 
> Link: https://github.com/boschsensortec/BME280_SensorAPI/blob/bme280_v3.5.1/bme280.c#L429
> Signed-off-by: Vasileios Amoiridis <vassilisamir-Re5JQEeQqe8AvxtiuMwx3w@...lic.gmane.org>
> ---
>   drivers/iio/pressure/bmp280-core.c | 26 ++++++++++++++++++++++++++
>   drivers/iio/pressure/bmp280.h      |  3 +++
>   2 files changed, 29 insertions(+)
> 
> diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> index c23515048081..e01c9369bd67 100644
> --- a/drivers/iio/pressure/bmp280-core.c
> +++ b/drivers/iio/pressure/bmp280-core.c
> @@ -965,6 +965,30 @@ static const unsigned long bme280_avail_scan_masks[] = {
>   	0
>   };
>   
> +static int bmp280_preinit(struct bmp280_data *data)
> +{
> +	unsigned int reg;
> +	int ret;
> +
> +	ret = regmap_write(data->regmap, BMP280_REG_RESET, BMP280_RST_SOFT_CMD);
> +	if (ret)
> +		return dev_err_probe(data->dev, ret,
> +				     "Failed to reset device.\n");
> +
> +	usleep_range(data->start_up_time, data->start_up_time + 500);
> +
> +	ret = regmap_read(data->regmap, BMP280_REG_STATUS, &reg);
> +	if (ret)
> +		return dev_err_probe(data->dev, ret,
> +				     "Failed to read status register.\n");
> +
> +	if (reg & BMP280_REG_STATUS_IM_UPDATE)
> +		return dev_err_probe(data->dev, ret,
> +				     "Failed to copy NVM contents.\n");

ret is 0 at this point.
Should a -E<something> be used instead?

CJ

> +
> +	return 0;
> +}
> +
>   static int bmp280_chip_config(struct bmp280_data *data)
>   {
>   	u8 osrs = FIELD_PREP(BMP280_OSRS_TEMP_MASK, data->oversampling_temp + 1) |
> @@ -1082,6 +1106,7 @@ const struct bmp280_chip_info bmp280_chip_info = {
>   	.read_temp = bmp280_read_temp,
>   	.read_press = bmp280_read_press,
>   	.read_calib = bmp280_read_calib,
> +	.preinit = bmp280_preinit,
>   
>   	.trigger_handler = bmp280_trigger_handler,
>   };
> @@ -1202,6 +1227,7 @@ const struct bmp280_chip_info bme280_chip_info = {
>   	.read_press = bmp280_read_press,
>   	.read_humid = bme280_read_humid,
>   	.read_calib = bme280_read_calib,
> +	.preinit = bmp280_preinit,
>   
>   	.trigger_handler = bme280_trigger_handler,
>   };
> diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> index 4e675401d61b..73516878d020 100644
> --- a/drivers/iio/pressure/bmp280.h
> +++ b/drivers/iio/pressure/bmp280.h
> @@ -205,6 +205,9 @@
>   #define BMP280_REG_CONFIG		0xF5
>   #define BMP280_REG_CTRL_MEAS		0xF4
>   #define BMP280_REG_STATUS		0xF3
> +#define BMP280_REG_STATUS_IM_UPDATE	BIT(0)
> +#define BMP280_REG_RESET		0xE0
> +#define BMP280_RST_SOFT_CMD		0xB6
>   
>   #define BMP280_REG_COMP_TEMP_START	0x88
>   #define BMP280_COMP_TEMP_REG_COUNT	6