On Thu, 15 Feb 2024 17:43:32 +0100
Vasileios Amoiridis <vassilisamir@xxxxxxxxx> wrote:
> According to the datasheet of BMP38x and BMP390 devices, in SPI
> operation, the first byte that returns after a read operation is
> garbage and it needs to be dropped and return the rest of the
> bytes.
Make it clear in the patch title that this is a fix and add a fixes tag.
>
> Signed-off-by: Vasileios Amoiridis <vassilisamir@xxxxxxxxx>
> ---
> drivers/iio/pressure/bmp280-spi.c | 47 ++++++++++++++++++++++++++++++-
> drivers/iio/pressure/bmp280.h | 2 ++
> 2 files changed, 48 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/pressure/bmp280-spi.c b/drivers/iio/pressure/bmp280-spi.c
> index 433d6fac83c4..c4b4a5d67f94 100644
> --- a/drivers/iio/pressure/bmp280-spi.c
> +++ b/drivers/iio/pressure/bmp280-spi.c
> @@ -35,6 +35,32 @@ 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 ret[BMP380_SPI_MAX_REG_COUNT_READ + 1];
Given you rely on val_size < 3 you should check for that explcitly rather than
potentially overflowing the buffer.
ret is not a good naming choice for this variable as it's commonly used for
integer return values. Call it read_buf or something like that.
> + ssize_t status;
> + u8 buf;
> +
> + memcpy(&buf, reg, reg_size);
> + buf |= 0x80;
Can you use regmap_bus read_flag_mask for this? Seems to apply to
all devices supported. + that's common for spi regmaps
Mind you I note the bmp280_regmap_spi_write() is masking the bit out which seems
backwards - all the registers are defined with the bit set for that part
but not the 380. Ah well - not part of this fix even if it's odd.
> +
> + /*
> + * According to the BMP380, BMP388, BMP390 datasheets, for a basic
> + * read operation, after the write is done, 2 bytes are received and
> + * the first one has to be dropped. The 2nd one is the requested
> + * value.
> + */
> + status = spi_write_then_read(spi, &buf, 1, ret, val_size + 1);
> + if (status)
> + return status;
> +
> + memcpy(val, ret + 1, val_size);
> +
> + return 0;
> +}
> +
> static struct regmap_bus bmp280_regmap_bus = {
> .write = bmp280_regmap_spi_write,
> .read = bmp280_regmap_spi_read,
> @@ -42,10 +68,18 @@ 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,
> + .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 +92,19 @@ 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)) {
> diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> index 4012387d7956..ca482b7e4295 100644
> --- a/drivers/iio/pressure/bmp280.h
> +++ b/drivers/iio/pressure/bmp280.h
> @@ -191,6 +191,8 @@
> #define BMP380_TEMP_SKIPPED 0x800000
> #define BMP380_PRESS_SKIPPED 0x800000
>
> +#define BMP380_SPI_MAX_REG_COUNT_READ 3
This doesn't seem useful as only used in one place.
> +
> /* BMP280 specific registers */
> #define BMP280_REG_HUMIDITY_LSB 0xFE
> #define BMP280_REG_HUMIDITY_MSB 0xFD
