[PATCH 4.9 018/102] iio: magnetometer: ak8974: Fix negative raw values in sysfs

[Greg Kroah-Hartman]

From: Stephan Gerhold <stephan@xxxxxxxxxxx>

commit b500c086e4110829a308c23e83a7cdc65b26228a upstream.

At the moment, reading from in_magn_*_raw in sysfs tends to return
large values around 65000, even though the output of ak8974 is actually
limited to Â32768. This happens because the value is never converted
to the signed 16-bit integer variant.

Add an explicit cast to s16 to fix this.

Fixes: 7c94a8b2ee8c ("iio: magn: add a driver for AK8974")
Signed-off-by: Stephan Gerhold <stephan@xxxxxxxxxxx>
Reviewed-by: Linus Waleij <linus.walleij@xxxxxxxxxx>
Cc: <Stable@xxxxxxxxxxxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/iio/magnetometer/ak8974.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/iio/magnetometer/ak8974.c
+++ b/drivers/iio/magnetometer/ak8974.c
@@ -477,7 +477,7 @@ static int ak8974_read_raw(struct iio_de
 		 * We read all axes and discard all but one, for optimized
 		 * reading, use the triggered buffer.
 		 */
-		*val = le16_to_cpu(hw_values[chan->address]);
+		*val = (s16)le16_to_cpu(hw_values[chan->address]);
 
 		ret = IIO_VAL_INT;
 	}