staging:iio:ad799x: Report scale as fractional value

Move the complexity of calculating the fixed point scale to the core.
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/staging/iio/adc/ad799x_core.c

@@ -163,7 +163,6 @@ static int ad799x_read_raw(struct iio_dev *indio_dev,
 {
 	int ret;
 	struct ad799x_state *st = iio_priv(indio_dev);
-	unsigned int scale_uv;
 
 	switch (m) {
 	case IIO_CHAN_INFO_RAW:
@@ -180,10 +179,9 @@ static int ad799x_read_raw(struct iio_dev *indio_dev,
 			RES_MASK(chan->scan_type.realbits);
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
-		scale_uv = (st->int_vref_mv * 1000) >> chan->scan_type.realbits;
-		*val =  scale_uv / 1000;
-		*val2 = (scale_uv % 1000) * 1000;
-		return IIO_VAL_INT_PLUS_MICRO;
+		*val = st->int_vref_mv;
+		*val2 = chan->scan_type.realbits;
+		return IIO_VAL_FRACTIONAL_LOG2;
 	}
 	return -EINVAL;
 }