Re: [PATCH] drivers: iio: pressure: Fixes BMP38x and BMP390 SPI support

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 19 Feb 2024 20:13:59 +0100
Vasileios Amoiridis <vassilisamir@gmail.com> wrote:

> According to the datasheet of BMP38x and BMP390 devices, for an SPI
> read operation the first byte that is returned needs to be dropped,
> and the rest of the bytes are the actual data returned from the
> sensor.
> 
> Fixes: 8d329309184d ("iio: pressure: bmp280: Add support for BMP380 sensor family")
> 
> Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>

Applied and marked for stable - with tweaks to header order and the space above
as per discussion.
> ---
>  drivers/iio/pressure/bmp280-spi.c | 49 ++++++++++++++++++++++++++++++-
>  1 file changed, 48 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/pressure/bmp280-spi.c b/drivers/iio/pressure/bmp280-spi.c
> index e8a5fed07e88..1972014dca93 100644
> --- a/drivers/iio/pressure/bmp280-spi.c
> +++ b/drivers/iio/pressure/bmp280-spi.c
> @@ -8,6 +8,7 @@
>  #include <linux/spi/spi.h>
>  #include <linux/err.h>
>  #include <linux/regmap.h>
> +#include <linux/bits.h>
>  
>  #include "bmp280.h"
>  
> @@ -35,6 +36,33 @@ static int bmp280_regmap_spi_read(void *context, const void *reg,
>  	return spi_write_then_read(spi, reg, reg_size, val, val_size);
>  }
>  
> +static int bmp380_regmap_spi_read(void *context, const void *reg,
> +				  size_t reg_size, void *val, size_t val_size)
> +{
> +	struct spi_device *spi = to_spi_device(context);
> +	u8 rx_buf[4];
> +	ssize_t status;
> +
> +	/*
> +	 * Maximum number of consecutive bytes read for a temperature or
> +	 * pressure measurement is 3.
> +	 */
> +	if (val_size > 3)
> +		return -EINVAL;
> +	/*
> +	 * According to the BMP3xx datasheets, for a basic SPI read opertion,
> +	 * the first byte needs to be dropped and the rest are the requested
> +	 * data.
> +	 */
> +	status = spi_write_then_read(spi, reg, 1, rx_buf, val_size + 1);
> +	if (status)
> +		return status;
> +
> +	memcpy(val, rx_buf + 1, val_size);
> +
> +	return 0;
> +}
> +
>  static struct regmap_bus bmp280_regmap_bus = {
>  	.write = bmp280_regmap_spi_write,
>  	.read = bmp280_regmap_spi_read,
> @@ -42,10 +70,19 @@ static struct regmap_bus bmp280_regmap_bus = {
>  	.val_format_endian_default = REGMAP_ENDIAN_BIG,
>  };
>  
> +static struct regmap_bus bmp380_regmap_bus = {
> +	.write = bmp280_regmap_spi_write,
> +	.read = bmp380_regmap_spi_read,
> +	.read_flag_mask = BIT(7),
> +	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
> +	.val_format_endian_default = REGMAP_ENDIAN_BIG,
> +};
> +
>  static int bmp280_spi_probe(struct spi_device *spi)
>  {
>  	const struct spi_device_id *id = spi_get_device_id(spi);
>  	const struct bmp280_chip_info *chip_info;
> +	struct regmap_bus *bmp_regmap_bus;
>  	struct regmap *regmap;
>  	int ret;
>  
> @@ -58,8 +95,18 @@ static int bmp280_spi_probe(struct spi_device *spi)
>  
>  	chip_info = spi_get_device_match_data(spi);
>  
> +	switch (chip_info->chip_id[0]) {
> +	case BMP380_CHIP_ID:
> +	case BMP390_CHIP_ID:
> +		bmp_regmap_bus = &bmp380_regmap_bus;
> +		break;
> +	default:
> +		bmp_regmap_bus = &bmp280_regmap_bus;
> +		break;
> +	}
> +
>  	regmap = devm_regmap_init(&spi->dev,
> -				  &bmp280_regmap_bus,
> +				  bmp_regmap_bus,
>  				  &spi->dev,
>  				  chip_info->regmap_config);
>  	if (IS_ERR(regmap)) {