hwmon: add fault attribute for voltage channels

Sometimes a voltage channel might have an hard failure (eg: a shorted
MOSFET). Hence, add a fault attribute to report such failures.

Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240129-b4-ltc4282-support-v4-2-fe75798164cc@analog.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/ABI/testing/sysfs-class-hwmon

@@ -149,6 +149,15 @@ Description:
 
 		RW
 
+What:		/sys/class/hwmon/hwmonX/inY_fault
+Description:
+		Reports a voltage hard failure (eg: shorted component)
+
+		- 1: Failed
+		- 0: Ok
+
+		RO
+
 What:		/sys/class/hwmon/hwmonX/cpuY_vid
 Description:
 		CPU core reference voltage.

drivers/hwmon/hwmon.c

@@ -510,6 +510,7 @@ static const char * const hwmon_in_attr_templates[] = {
 	[hwmon_in_rated_min] = "in%d_rated_min",
 	[hwmon_in_rated_max] = "in%d_rated_max",
 	[hwmon_in_beep] = "in%d_beep",
+	[hwmon_in_fault] = "in%d_fault",
 };
 
 static const char * const hwmon_curr_attr_templates[] = {

include/linux/hwmon.h

@@ -141,6 +141,7 @@ enum hwmon_in_attributes {
 	hwmon_in_rated_min,
 	hwmon_in_rated_max,
 	hwmon_in_beep,
+	hwmon_in_fault,
 };
 
 #define HWMON_I_ENABLE		BIT(hwmon_in_enable)
@@ -162,6 +163,7 @@ enum hwmon_in_attributes {
 #define HWMON_I_RATED_MIN	BIT(hwmon_in_rated_min)
 #define HWMON_I_RATED_MAX	BIT(hwmon_in_rated_max)
 #define HWMON_I_BEEP		BIT(hwmon_in_beep)
+#define HWMON_I_FAULT		BIT(hwmon_in_fault)
 
 enum hwmon_curr_attributes {
 	hwmon_curr_enable,