[PATCH 3.16.y-ckt 046/165] iio: imu: adis16400: Fix sign extension

[Luis Henriques]

3.16.7-ckt9 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rasmus Villemoes <linux at rasmusvillemoes.dk>

commit 19e353f2b344ad86cea6ebbc0002e5f903480a90 upstream.

The intention is obviously to sign-extend a 12 bit quantity. But
because of C's promotion rules, the assignment is equivalent to "val16
&= 0xfff;". Use the proper API for this.

Signed-off-by: Rasmus Villemoes <linux at rasmusvillemoes.dk>
Acked-by: Lars-Peter Clausen <lars at metafoo.de>
Signed-off-by: Jonathan Cameron <jic23 at kernel.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/iio/imu/adis16400_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/imu/adis16400_core.c b/drivers/iio/imu/adis16400_core.c
index 433583b6f800..8ca469c17a91 100644
--- a/drivers/iio/imu/adis16400_core.c
+++ b/drivers/iio/imu/adis16400_core.c
@@ -26,6 +26,7 @@
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/debugfs.h>
+#include <linux/bitops.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -447,7 +448,7 @@ static int adis16400_read_raw(struct iio_dev *indio_dev,
 		mutex_unlock(&indio_dev->mlock);
 		if (ret)
 			return ret;
-		val16 = ((val16 & 0xFFF) << 4) >> 4;
+		val16 = sign_extend32(val16, 11);
 		*val = val16;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_OFFSET: