From 37e05ea2c5fbb9bcea8b1b1020fb0853fbf7ab0b Mon Sep 17 00:00:00 2001
From: Marcus Folkesson <marcus.folkesson@gmail.com>
Date: Fri, 22 Jul 2022 15:07:18 +0200
Subject: [PATCH] iio: adc: mcp3911: make use of the sign bit

[ Upstream commit 8f89e33bf040bbef66386c426198622180233178 ]

The device supports negative values as well.

Fixes: 3a89b289df5d ("iio: adc: add support for mcp3911")
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220722130726.7627-2-marcus.folkesson@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/iio/adc/mcp3911.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index 1cb4590fe412..f581cefb6719 100644
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -113,6 +113,8 @@ static int mcp3911_read_raw(struct iio_dev *indio_dev,
 		if (ret)
 			goto out;
 
+		*val = sign_extend32(*val, 23);
+
 		ret = IIO_VAL_INT;
 		break;