Patch "hwmon: (sch5627) Disallow write access if virtual registers are locked" has been added to the 6.5-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    hwmon: (sch5627) Disallow write access if virtual registers are locked

to the 6.5-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hwmon-sch5627-disallow-write-access-if-virtual-regis.patch
and it can be found in the queue-6.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 1b092bd82b141d70ef7572c9f5e171c69193face
Author: Armin Wolf <W_Armin@xxxxxx>
Date:   Thu Sep 7 07:26:36 2023 +0200

    hwmon: (sch5627) Disallow write access if virtual registers are locked
    
    [ Upstream commit 7da8a635436029957c5350da3acf51d78ed64071 ]
    
    When the lock bit inside SCH5627_REG_CTRL is set, then the virtual
    registers become read-only until the next power cycle.
    Disallow write access to those registers in such a case.
    
    Tested on a Fujitsu Esprimo P720.
    
    Fixes: aa9f833dfc12 ("hwmon: (sch5627) Add pwmX_auto_channels_temp support")
    Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
    Link: https://lore.kernel.org/r/20230907052639.16491-3-W_Armin@xxxxxx
    Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/hwmon/sch5627.c b/drivers/hwmon/sch5627.c
index 0eefb8c0aef25..bf408e35e2c32 100644
--- a/drivers/hwmon/sch5627.c
+++ b/drivers/hwmon/sch5627.c
@@ -34,6 +34,7 @@
 #define SCH5627_REG_CTRL		0x40
 
 #define SCH5627_CTRL_START		BIT(0)
+#define SCH5627_CTRL_LOCK		BIT(1)
 #define SCH5627_CTRL_VBAT		BIT(4)
 
 #define SCH5627_NO_TEMPS		8
@@ -231,6 +232,14 @@ static int reg_to_rpm(u16 reg)
 static umode_t sch5627_is_visible(const void *drvdata, enum hwmon_sensor_types type, u32 attr,
 				  int channel)
 {
+	const struct sch5627_data *data = drvdata;
+
+	/* Once the lock bit is set, the virtual registers become read-only
+	 * until the next power cycle.
+	 */
+	if (data->control & SCH5627_CTRL_LOCK)
+		return 0444;
+
 	if (type == hwmon_pwm && attr == hwmon_pwm_auto_channels_temp)
 		return 0644;