[PATCH] iio: temperature: mcp9600: Fix temperature reading for negative values

[Dimitri Fedrau]

Temperature is stored as 16bit value in two's complement format. Current
implementation ignores the sign bit. Make it aware of the sign bit by
using sign_extend32.

Fixes: 3f6b9598b6df ("iio: temperature: Add MCP9600 thermocouple EMF converter")
Signed-off-by: Dimitri Fedrau <dima.fedrau@xxxxxxxxx>
---
 drivers/iio/temperature/mcp9600.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/temperature/mcp9600.c b/drivers/iio/temperature/mcp9600.c
index 46845804292b..7a3eef5d5e75 100644
--- a/drivers/iio/temperature/mcp9600.c
+++ b/drivers/iio/temperature/mcp9600.c
@@ -52,7 +52,8 @@ static int mcp9600_read(struct mcp9600_data *data,
 
 	if (ret < 0)
 		return ret;
-	*val = ret;
+
+	*val = sign_extend32(ret, 15);
 
 	return 0;
 }
-- 
2.39.2