Re: [PATCH 1/2 v2] iio: st_accel: support 8bit channel data

[Jonathan Cameron <jic23@kernel.org>]

On 19/05/15 14:37, Linus Walleij wrote:
> Some sensors like the LIS331DL only support 8bit data by a single
> register per axis. These utilize the MSB byte. Make it possible
> to register these apropriately.
> 
> A oneliner change is needed in the ST sensors core to handle 8bit
> reads as this is the first supported 8bit sensor.
> 
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Looks good to me.  I'll let these sit for a few days though to
give Denis and others a chance to check them out before I apply them.

Thanks
Jonathan 
> ---
> ChangeLog v1->v2:
> - Change the .storage type to 8 bits.
> - Alter the st_sensors_core to cast the byte properly to a signed
>   int.
> ---
>  drivers/iio/accel/st_accel_core.c               | 16 ++++++++++++++++
>  drivers/iio/common/st_sensors/st_sensors_core.c |  4 +++-
>  2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/accel/st_accel_core.c b/drivers/iio/accel/st_accel_core.c
> index 58d1d13d552a..ad19fb4304df 100644
> --- a/drivers/iio/accel/st_accel_core.c
> +++ b/drivers/iio/accel/st_accel_core.c
> @@ -153,6 +153,22 @@
>  #define ST_ACCEL_4_IG1_EN_MASK			0x08
>  #define ST_ACCEL_4_MULTIREAD_BIT		true
>  
> +static const struct iio_chan_spec st_accel_8bit_channels[] = {
> +	ST_SENSORS_LSM_CHANNELS(IIO_ACCEL,
> +			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> +			ST_SENSORS_SCAN_X, 1, IIO_MOD_X, 's', IIO_LE, 8, 8,
> +			ST_ACCEL_DEFAULT_OUT_X_L_ADDR+1),
> +	ST_SENSORS_LSM_CHANNELS(IIO_ACCEL,
> +			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> +			ST_SENSORS_SCAN_Y, 1, IIO_MOD_Y, 's', IIO_LE, 8, 8,
> +			ST_ACCEL_DEFAULT_OUT_Y_L_ADDR+1),
> +	ST_SENSORS_LSM_CHANNELS(IIO_ACCEL,
> +			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> +			ST_SENSORS_SCAN_Z, 1, IIO_MOD_Z, 's', IIO_LE, 8, 8,
> +			ST_ACCEL_DEFAULT_OUT_Z_L_ADDR+1),
> +	IIO_CHAN_SOFT_TIMESTAMP(3)
> +};
> +
>  static const struct iio_chan_spec st_accel_12bit_channels[] = {
>  	ST_SENSORS_LSM_CHANNELS(IIO_ACCEL,
>  			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> diff --git a/drivers/iio/common/st_sensors/st_sensors_core.c b/drivers/iio/common/st_sensors/st_sensors_core.c
> index 7973c0457042..9007b618d434 100644
> --- a/drivers/iio/common/st_sensors/st_sensors_core.c
> +++ b/drivers/iio/common/st_sensors/st_sensors_core.c
> @@ -434,7 +434,9 @@ static int st_sensors_read_axis_data(struct iio_dev *indio_dev,
>  	if (err < 0)
>  		goto st_sensors_free_memory;
>  
> -	if (byte_for_channel == 2)
> +	if (byte_for_channel == 1)
> +		*data = (s8)*outdata;
> +	else if (byte_for_channel == 2)
>  		*data = (s16)get_unaligned_le16(outdata);
>  	else if (byte_for_channel == 3)
>  		*data = (s32)st_sensors_get_unaligned_le24(outdata);
>