blob: f80ae1bb23076fafb2e0b0fd61348c27beb5bef5 [file] [log] [blame]
From: Gregor Boirie <gregor.boirie@parrot.com>
Date: Fri, 2 Sep 2016 20:27:46 +0200
Subject: iio:core: fix IIO_VAL_FRACTIONAL sign handling
commit 171c0091837c81ed5c949fec6966bb5afff2d1cf upstream.
7985e7c100 ("iio: Introduce a new fractional value type") introduced a
new IIO_VAL_FRACTIONAL value type meant to represent rational type numbers
expressed by a numerator and denominator combination.
Formating of IIO_VAL_FRACTIONAL values relies upon do_div() usage. This
fails handling negative values properly since parameters are reevaluated
as unsigned values.
Fix this by using div_s64_rem() instead. Computed integer part will carry
properly signed value. Formatted fractional part will always be positive.
Fixes: 7985e7c100 ("iio: Introduce a new fractional value type")
Signed-off-by: Gregor Boirie <gregor.boirie@parrot.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/iio/industrialio-core.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -404,9 +404,8 @@ ssize_t iio_format_value(char *buf, unsi
return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
case IIO_VAL_FRACTIONAL:
tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
- vals[1] = do_div(tmp, 1000000000LL);
- vals[0] = tmp;
- return sprintf(buf, "%d.%09u\n", vals[0], vals[1]);
+ vals[0] = (int)div_s64_rem(tmp, 1000000000, &vals[1]);
+ return sprintf(buf, "%d.%09u\n", vals[0], abs(vals[1]));
case IIO_VAL_FRACTIONAL_LOG2:
tmp = (s64)vals[0] * 1000000000LL >> vals[1];
vals[1] = do_div(tmp, 1000000000LL);