linux-kernel - [PATCH v3 01/11] hwmon: (amc6821) Stop accepting invalid pwm values

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Message-Id: <20240704175207.2684012-2-linux@roeck-us.net>
Date: Thu,  4 Jul 2024 10:51:57 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: linux-hwmon@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Farouk Bouabid <farouk.bouabid@...rry.de>,
	Quentin Schulz <quentin.schulz@...rry.de>,
	Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH v3 01/11] hwmon: (amc6821) Stop accepting invalid pwm values

The pwm value range is well defined from 0..255. Don't accept any values
outside this range.

This changes the valid range of pwm1_auto_point2_pwm from 0..254 to 0..255,
meaning it can now be equivalent to not only pwm1_auto_point1_pwm (which is
always 0) but also to pwm1_auto_point3_pwm (which is always 255). While
that may not be practical, there seems to be no technical reason for
preventing a user from doing it.

Reviewed-by: Quentin Schulz <quentin.schulz@...rry.de>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
v3: Change valid range of  pwm1_auto_point2_pwm from [0..254] to
    [0, 255]
    Add Quentin's Reviewed-by: tag

v2: Use kstrtou8() instead of kstrtol() where possible.
    Limit range of pwm1_auto_point_pwm to 0..254 in patch 1
    instead of limiting it later, and do not accept invalid
    values for the attribute.


 drivers/hwmon/amc6821.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/hwmon/amc6821.c b/drivers/hwmon/amc6821.c
index 9b02b304c2f5..dc35e9b21f91 100644
--- a/drivers/hwmon/amc6821.c
+++ b/drivers/hwmon/amc6821.c
@@ -355,13 +355,13 @@ static ssize_t pwm1_store(struct device *dev,
 {
 	struct amc6821_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
-	long val;
-	int ret = kstrtol(buf, 10, &val);
+	u8 val;
+	int ret = kstrtou8(buf, 10, &val);
 	if (ret)
 		return ret;
 
 	mutex_lock(&data->update_lock);
-	data->pwm1 = clamp_val(val , 0, 255);
+	data->pwm1 = val;
 	i2c_smbus_write_byte_data(client, AMC6821_REG_DCY, data->pwm1);
 	mutex_unlock(&data->update_lock);
 	return count;
@@ -558,13 +558,15 @@ static ssize_t pwm1_auto_point_pwm_store(struct device *dev,
 	struct amc6821_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	int dpwm;
-	long val;
-	int ret = kstrtol(buf, 10, &val);
+	u8 val;
+	int ret;
+
+	ret = kstrtou8(buf, 10, &val);
 	if (ret)
 		return ret;
 
 	mutex_lock(&data->update_lock);
-	data->pwm1_auto_point_pwm[1] = clamp_val(val, 0, 254);
+	data->pwm1_auto_point_pwm[1] = val;
 	if (i2c_smbus_write_byte_data(client, AMC6821_REG_DCY_LOW_TEMP,
 			data->pwm1_auto_point_pwm[1])) {
 		dev_err(&client->dev, "Register write error, aborting.\n");
-- 
2.39.2