linux-kernel - [PATCH v12 04/16] iio: afe: rescale: use s64 for temporary scale calculations

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Date:   Sat,  8 Jan 2022 15:53:07 -0500
From:   Liam Beguin <liambeguin@...il.com>
To:     liambeguin@...il.com, peda@...ntia.se, jic23@...nel.org,
        andy.shevchenko@...il.com, lars@...afoo.de
Cc:     linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        devicetree@...r.kernel.org, robh+dt@...nel.org
Subject: [PATCH v12 04/16] iio: afe: rescale: use s64 for temporary scale calculations

All four scaling coefficients can take signed values.
Make tmp a signed 64-bit integer and switch to div_s64() to preserve
signs during 64-bit divisions.

Fixes: 8b74816b5a9a ("iio: afe: rescale: new driver")
Signed-off-by: Liam Beguin <liambeguin@...il.com>
Reviewed-by: Peter Rosin <peda@...ntia.se>
---
 drivers/iio/afe/iio-rescale.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index 774eb3044edd..271d73e420c4 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -39,7 +39,7 @@ static int rescale_read_raw(struct iio_dev *indio_dev,
 			    int *val, int *val2, long mask)
 {
 	struct rescale *rescale = iio_priv(indio_dev);
-	unsigned long long tmp;
+	s64 tmp;
 	int ret;
 
 	switch (mask) {
@@ -77,10 +77,10 @@ static int rescale_read_raw(struct iio_dev *indio_dev,
 			*val2 = rescale->denominator;
 			return IIO_VAL_FRACTIONAL;
 		case IIO_VAL_FRACTIONAL_LOG2:
-			tmp = *val * 1000000000LL;
-			do_div(tmp, rescale->denominator);
+			tmp = (s64)*val * 1000000000LL;
+			tmp = div_s64(tmp, rescale->denominator);
 			tmp *= rescale->numerator;
-			do_div(tmp, 1000000000LL);
+			tmp = div_s64(tmp, 1000000000LL);
 			*val = tmp;
 			return ret;
 		default:
-- 
2.34.0