linux-kernel - Re: [PATCH v2 2/7] iio: pressure: bmp280: Add support for bmp280 soft reset

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Message-ID: <20240821213230.GB473841@vamoiridPC>
Date: Wed, 21 Aug 2024 23:32:30 +0200
From: Vasileios Amoiridis <vassilisamir@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Vasileios Amoiridis <vassilisamir@...il.com>, lars@...afoo.de,
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
	andriy.shevchenko@...ux.intel.com, ang.iglesiasg@...il.com,
	linus.walleij@...aro.org, biju.das.jz@...renesas.com,
	javier.carrasco.cruz@...il.com, semen.protsenko@...aro.org,
	579lpy@...il.com, ak@...klinger.de, linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/7] iio: pressure: bmp280: Add support for bmp280
 soft reset

On Sun, Jul 28, 2024 at 04:49:01PM +0100, Jonathan Cameron wrote:
> On Fri, 26 Jul 2024 01:10:34 +0200
> Vasileios Amoiridis <vassilisamir@...il.com> wrote:
> 
> > 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@...il.com>
> Trivial passing comment seeing as you are going do be doing a v3 anyway.
> 
> Jonathan
> 
> > ---
> >  drivers/iio/pressure/bmp280-core.c | 28 ++++++++++++++++++++++++++++
> >  drivers/iio/pressure/bmp280.h      |  3 +++
> >  2 files changed, 31 insertions(+)
> > 
> > diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
> > index d5e5eb22667a..acbc33aacc09 100644
> > --- a/drivers/iio/pressure/bmp280-core.c
> > +++ b/drivers/iio/pressure/bmp280-core.c
> > @@ -963,6 +963,32 @@ 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) {
> > +		dev_err(data->dev, "Failed to reset device.\n");
> > +		return ret;
> Is this only ever called from probe?
> 
> If so, return dev_err_probe() which will save a few lines of code.
> 

Hi Jonathan,

Indeed, this is being called only from probe so I could change that as you
proposed!

Cheers,
Vasilis

> > +	}
> > +
> > +	usleep_range(data->start_up_time, data->start_up_time + 500);
> > +
> > +	ret = regmap_read(data->regmap, BMP280_REG_STATUS, &reg);
> > +	if (ret) {
> > +		dev_err(data->dev, "Failed to read status register.\n");
> > +		return ret;
> > +	}
> > +	if (reg & BMP280_REG_STATUS_IM_UPDATE) {
> > +		dev_err(data->dev, "Failed to copy NVM contents.\n");
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  static int bmp280_chip_config(struct bmp280_data *data)
> >  {
> >  	u8 osrs = FIELD_PREP(BMP280_OSRS_TEMP_MASK, data->oversampling_temp + 1) |
> > @@ -1079,6 +1105,7 @@ 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,
> >  };
> > @@ -1196,6 +1223,7 @@ 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 9bea0b84d2f4..a9f220c1f77a 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
>