linux-kernel - [PATCH AUTOSEL 4.19 514/671] hwmon: (lm75) Fix write operations for negative temperatures

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Message-Id: <20200116170509.12787-251-sashal@kernel.org>
Date:   Thu, 16 Jan 2020 12:02:32 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Iker Perez del Palomar Sustatxa 
        <iker.perez@...ethink.co.uk>, Sasha Levin <sashal@...nel.org>,
        linux-hwmon@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 514/671] hwmon: (lm75) Fix write operations for negative temperatures

From: Guenter Roeck <linux@...ck-us.net>

[ Upstream commit 7d82fcc9d9e81241778aaa22fda7be753e237d86 ]

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@...ethink.co.uk>
Fixes: e65365fed87f ("hwmon: (lm75) Convert to use regmap")
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/hwmon/lm75.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwmon/lm75.c b/drivers/hwmon/lm75.c
index 49f4b33a5685..7f28912c9abc 100644
--- a/drivers/hwmon/lm75.c
+++ b/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,
-- 
2.20.1