[PATCH 6.6.y] iio: adc: rtq6056: Correct the sign bit index

[Sasha Levin <sashal@kernel.org>]

From: ChiYuan Huang <cy_huang@richtek.com>

[ Upstream commit 9b45744bf09fc2a3287e05287141d6e123c125a7 ]

The vshunt/current reported register is a signed 16bit integer. The
sign bit index should be '15', not '16'.

Fixes: 4396f45d211b ("iio: adc: Add rtq6056 support")
Reported-by: Andy Hsu <andy_ya_hsu@wiwynn.com>
Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[ adapted switch statement to existing if-else structure for sign_extend32() fix ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iio/adc/rtq6056.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/adc/rtq6056.c b/drivers/iio/adc/rtq6056.c
index ad4cea6839b27..3ffdcb9f88336 100644
--- a/drivers/iio/adc/rtq6056.c
+++ b/drivers/iio/adc/rtq6056.c
@@ -171,7 +171,7 @@ static int rtq6056_adc_read_channel(struct rtq6056_priv *priv,
 	if (addr == RTQ6056_REG_BUSVOLT || addr == RTQ6056_REG_POWER)
 		*val = regval;
 	else
-		*val = sign_extend32(regval, 16);
+		*val = sign_extend32(regval, 15);
 
 	return IIO_VAL_INT;
 }
-- 
2.51.0