From: Liam Beguin <lvb@xxxxxxxxxx>
The IIO_VAL_FRACTIONAL_LOG2 scale type doesn't return the expected
scale. Update the case so that the rescaler returns a fractional type
and a more precise scale.
Signed-off-by: Liam Beguin <lvb@xxxxxxxxxx>
---
drivers/iio/afe/iio-rescale.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index abd7ad73d1ce..e37a9766080c 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -47,12 +47,17 @@ int rescale_process_scale(struct rescale *rescale, int scale_type,
*val2 = rescale->denominator;
return IIO_VAL_FRACTIONAL;
case IIO_VAL_FRACTIONAL_LOG2:
- tmp = *val * 1000000000LL;
- do_div(tmp, rescale->denominator);
- tmp *= rescale->numerator;
- do_div(tmp, 1000000000LL);
+ if (check_mul_overflow(*val, rescale->numerator, (s32 *)&tmp) ||
+ check_mul_overflow(rescale->denominator, (1 << *val2), (s32 *)&tmp2)) {
+ tmp = (s64)*val * rescale->numerator;
+ tmp2 = (s64)rescale->denominator * (1 << *val2);
+ factor = gcd(abs(tmp), abs(tmp2));
+ tmp = div_s64(tmp, factor);
+ tmp2 = div_s64(tmp2, factor);
+ }
*val = tmp;
- return scale_type;
+ *val2 = tmp2;
+ return IIO_VAL_FRACTIONAL;
case IIO_VAL_INT_PLUS_NANO:
case IIO_VAL_INT_PLUS_MICRO:
if (scale_type == IIO_VAL_INT_PLUS_NANO)
--
2.30.1.489.g328c10930387
