iio: imu: adis16400: Fix sign extension

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@rasmusvillemoes.dk>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
[bwh: Backported to 3.2: adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/staging/iio/imu/adis16400_core.c b/drivers/staging/iio/imu/adis16400_core.c
index d082a37..57cb92f 100644 (file)
--- a/drivers/staging/iio/imu/adis16400_core.c
+++ b/drivers/staging/iio/imu/adis16400_core.c
@@ -25,6 +25,7 @@
 #include <linux/sysfs.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/sysfs.h>
 #include <linux/list.h>
 #include <linux/module.h>

+#include <linux/bitops.h>

 
 #include "../iio.h"
 #include "../sysfs.h"
 
 #include "../iio.h"
 #include "../sysfs.h"


@@ -541,7 +542,7 @@ static int adis16400_read_raw(struct iio_dev *indio_dev,
                mutex_unlock(&indio_dev->mlock);
                if (ret)
                        return ret;
                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 (1 << IIO_CHAN_INFO_OFFSET_SEPARATE):
                *val = val16;
                return IIO_VAL_INT;
        case (1 << IIO_CHAN_INFO_OFFSET_SEPARATE):