On Mon, 2 Nov 2020 00:22:11 +0100
Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> It happens that an ADC will only provide raw or processed
> voltage conversion channels. (adc/ab8500-gpadc.c).
> On the Samsung GT-I9070 this is used for a light sensor
> and current sense amplifier so we need to think of something.
>
> The idea is to allow processed channels and scale them
> with 1/1 and then the rescaler can modify the result
> on top.
>
> Cc: Peter Rosin <peda@xxxxxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Sorry, I kept leaving this to last as it was in the 'needed thought'
pile - then running out of time and not getting to it.
Anyhow, I think this is the best we can do for the situation
you describe so I'm happy with this.
@Peter, I definitely want your input on this one as well though
before I apply it!
Jonathan
> ---
> drivers/iio/afe/iio-rescale.c | 31 +++++++++++++++++++++++++++----
> 1 file changed, 27 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
> index e42ea2b1707d..ea90034cb257 100644
> --- a/drivers/iio/afe/iio-rescale.c
> +++ b/drivers/iio/afe/iio-rescale.c
> @@ -29,6 +29,7 @@ struct rescale {
> struct iio_channel *source;
> struct iio_chan_spec chan;
> struct iio_chan_spec_ext_info *ext_info;
> + bool chan_processed;
> s32 numerator;
> s32 denominator;
> };
> @@ -43,10 +44,27 @@ static int rescale_read_raw(struct iio_dev *indio_dev,
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> - return iio_read_channel_raw(rescale->source, val);
> + if (rescale->chan_processed)
> + /*
> + * When only processed channels are supported, we
> + * read the processed data and scale it by 1/1
> + * augmented with whatever the rescaler has calculated.
> + */
> + return iio_read_channel_processed(rescale->source, val);
> + else
> + return iio_read_channel_raw(rescale->source, val);
>
> case IIO_CHAN_INFO_SCALE:
> - ret = iio_read_channel_scale(rescale->source, val, val2);
> + if (rescale->chan_processed) {
> + /*
> + * Processed channels are scaled 1-to-1
> + */
> + ret = IIO_VAL_FRACTIONAL;
> + *val = 1;
> + *val2 = 1;
> + } else {
> + ret = iio_read_channel_scale(rescale->source, val, val2);
> + }
> switch (ret) {
> case IIO_VAL_FRACTIONAL:
> *val *= rescale->numerator;
> @@ -132,8 +150,13 @@ static int rescale_configure_channel(struct device *dev,
>
> if (!iio_channel_has_info(schan, IIO_CHAN_INFO_RAW) ||
> !iio_channel_has_info(schan, IIO_CHAN_INFO_SCALE)) {
> - dev_err(dev, "source channel does not support raw/scale\n");
> - return -EINVAL;
> + if (iio_channel_has_info(schan, IIO_CHAN_INFO_PROCESSED)) {
> + dev_info(dev, "using processed channel\n");
> + rescale->chan_processed = true;
> + } else {
> + dev_err(dev, "source channel does not support raw+scale or processed data\n");
> + return -EINVAL;
> + }
> }
>
> chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
