[PATCH 1/4] iio: trigger: stm32-timer: fix quadrature mode get routine

[Jonathan Cameron]

On Thu, 27 Jul 2017 18:18:57 +0200
Fabrice Gasnier <fabrice.gasnier at st.com> wrote:

> Fixes: 4adec7da0536 ("iio: stm32 trigger: Add quadrature encoder device")
> 
> SMS bitfiled is mode + 1. After reset, upon boot, SMS = 0. When reading
> from sysfs, stm32_get_quadrature_mode() returns -1 (e.g. -EPERM) which is
> wrong error code here. So, check SMS bitfiled matches valid encoder mode,
> or return -EINVAL.
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier at st.com>
Applied to the fixes-togreg branch of iio.git.

Thanks,

Jonathan
> ---
>  drivers/iio/trigger/stm32-timer-trigger.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
> index d22bc56..6aa73d6 100644
> --- a/drivers/iio/trigger/stm32-timer-trigger.c
> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
> @@ -571,11 +571,14 @@ static int stm32_get_quadrature_mode(struct iio_dev *indio_dev,
>  {
>  	struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>  	u32 smcr;
> +	int mode;
>  
>  	regmap_read(priv->regmap, TIM_SMCR, &smcr);
> -	smcr &= TIM_SMCR_SMS;
> +	mode = (smcr & TIM_SMCR_SMS) - 1;
> +	if ((mode < 0) || (mode > ARRAY_SIZE(stm32_quadrature_modes)))
> +		return -EINVAL;
>  
> -	return smcr - 1;
> +	return mode;
>  }
>  
>  static const struct iio_enum stm32_quadrature_mode_enum = {