Re: [PATCH v3 6/9] staging: iio: ad2s1200: Add scaling factor for angular velocity channel

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 23 Apr 2018 00:03:59 +0200
David Veenstra <davidjulianveenstra@gmail.com> wrote:

> The sysfs iio ABI states radians per second is expected as the unit for
> angular velocity, but the 12-bit angular velocity register has rps
Really small point, but rps is a bit ambiguous given we are
talking about converting to radian's per second ;)

revs is the 'common' name for what it currently is I think.

Otherwise this looks good.

Jonathan


> as its unit. So a scaling factor of approximately 2 * Pi is
> added to the angular velocity channel.
> 
> Signed-off-by: David Veenstra <davidjulianveenstra@gmail.com>
> ---
> Changes in v3:
>  - A decimal approximation of the scale is used, instead
>    of a fractional approximation.
>  - Remove unneeded explanation of iio_convert_raw_to_processed.
> 
>  drivers/staging/iio/resolver/ad2s1200.c | 71 +++++++++++++++++++++------------
>  1 file changed, 45 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/staging/iio/resolver/ad2s1200.c b/drivers/staging/iio/resolver/ad2s1200.c
> index 3c7163610ff6..3e1696e52c38 100644
> --- a/drivers/staging/iio/resolver/ad2s1200.c
> +++ b/drivers/staging/iio/resolver/ad2s1200.c
> @@ -57,37 +57,55 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev,
>  	struct ad2s1200_state *st = iio_priv(indio_dev);
>  	int ret = 0;
>  
> -	mutex_lock(&st->lock);
> -	gpiod_set_value(st->sample, 0);
> -
> -	/* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
> -	udelay(1);
> -	gpiod_set_value(st->sample, 1);
> -	gpiod_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
> -
> -	ret = spi_read(st->sdev, &st->rx, 2);
> -	if (ret < 0) {
> +	switch (m) {
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_ANGL_VEL:
> +			/* 2 * Pi ~= 6.283185 */
> +			*val = 6;
> +			*val2 = 283185;
> +			return IIO_VAL_INT_PLUS_MICRO;
> +		default:
> +			return -EINVAL;
> +		}
> +		break;
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&st->lock);
> +		gpiod_set_value(st->sample, 0);
> +
> +		/* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
> +		udelay(1);
> +		gpiod_set_value(st->sample, 1);
> +		gpiod_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
> +
> +		ret = spi_read(st->sdev, &st->rx, 2);
> +		if (ret < 0) {
> +			mutex_unlock(&st->lock);
> +			return ret;
> +		}
> +
> +		switch (chan->type) {
> +		case IIO_ANGL:
> +			*val = be16_to_cpup(&st->rx) >> 4;
> +			break;
> +		case IIO_ANGL_VEL:
> +			*val = sign_extend32(be16_to_cpup(&st->rx) >> 4, 11);
> +			break;
> +		default:
> +			mutex_unlock(&st->lock);
> +			return -EINVAL;
> +		}
> +
> +		/* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
> +		udelay(1);
>  		mutex_unlock(&st->lock);
> -		return ret;
> -	}
>  
> -	switch (chan->type) {
> -	case IIO_ANGL:
> -		*val = be16_to_cpup(&st->rx) >> 4;
> -		break;
> -	case IIO_ANGL_VEL:
> -		*val = sign_extend32(be16_to_cpup(&st->rx) >> 4, 11);
> -		break;
> +		return IIO_VAL_INT;
>  	default:
> -		mutex_unlock(&st->lock);
> -		return -EINVAL;
> +		break;
>  	}
>  
> -	/* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
> -	udelay(1);
> -	mutex_unlock(&st->lock);
> -
> -	return IIO_VAL_INT;
> +	return -EINVAL;
>  }
>  
>  static const struct iio_chan_spec ad2s1200_channels[] = {
> @@ -101,6 +119,7 @@ static const struct iio_chan_spec ad2s1200_channels[] = {
>  		.indexed = 1,
>  		.channel = 0,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
>  	}
>  };
>