hwmon: (lm75) Fix write operations for negative temperatures

[ Upstream commit 7d82fcc9 ]

Writes into limit registers fail if the temperature written is negative.
The regmap write operation checks the value range, regmap_write accepts
an unsigned int as parameter, and the temperature value passed to
regmap_write is kept in a variable declared as long. Negative values
are converted large unsigned integers, which fails the range check.
Fix by type casting the temperature to u16 when calling regmap_write().

Cc: Iker Perez del Palomar Sustatxa <iker.perez@codethink.co.uk>
Fixes: e65365fe ("hwmon: (lm75) Convert to use regmap")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/hwmon/lm75.c

@@ -165,7 +165,7 @@ static int lm75_write(struct device *dev, enum hwmon_sensor_types type,
 	temp = DIV_ROUND_CLOSEST(temp  << (resolution - 8),
 				 1000) << (16 - resolution);
 
-	return regmap_write(data->regmap, reg, temp);
+	return regmap_write(data->regmap, reg, (u16)temp);
 }
 
 static umode_t lm75_is_visible(const void *data, enum hwmon_sensor_types type,