iio:ad5791: Report scale as fractional value

Move the complexity of calculating the fixed point scale to the core.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/dac/ad5791.c b/drivers/iio/dac/ad5791.c
index 3cee89be68c3ac672dc697ea82c843446d71e323..d64acbd89482b82308601d88cb742446b865856a 100644 (file)
--- a/drivers/iio/dac/ad5791.c
+++ b/drivers/iio/dac/ad5791.c
@@ -270,9 +270,9 @@ static int ad5791_read_raw(struct iio_dev *indio_dev,
                *val >>= chan->scan_type.shift;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
-               *val = 0;
-               *val2 = (((u64)st->vref_mv) * 1000000ULL) >> chan->scan_type.realbits;
-               return IIO_VAL_INT_PLUS_MICRO;
+               *val = st->vref_mv;
+               *val2 = (1 << chan->scan_type.realbits) - 1;
+               return IIO_VAL_FRACTIONAL;
        case IIO_CHAN_INFO_OFFSET:
                val64 = (((u64)st->vref_neg_mv) << chan->scan_type.realbits);
                do_div(val64, st->vref_mv);