[PATCH] hwmon: (acpi_power_meter) Fix 18.45 TW bug

[Armin Wolf]

The ACPI specification says:

"If an error occurs while obtaining the meter reading or if the value
is not available then an Integer with all bits set is returned"

This integer can also be 64-bit wide on ACPI 2.0 and later systems,
so we have to check for that too.

Compile-tested only.

Reported-by: Grant Slater <github@xxxxxxxxxxxxx>
Closes: https://github.com/lm-sensors/lm-sensors/issues/460
Fixes: 1fefca6c57fb ("hwmon: (acpi_power_meter) Fix 4.29 MW bug")
Signed-off-by: Armin Wolf <W_Armin@xxxxxx>
---
 drivers/hwmon/acpi_power_meter.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/acpi_power_meter.c b/drivers/hwmon/acpi_power_meter.c
index d8e871509405..3891962f03db 100644
--- a/drivers/hwmon/acpi_power_meter.c
+++ b/drivers/hwmon/acpi_power_meter.c
@@ -10,6 +10,7 @@
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/jiffies.h>
+#include <linux/limits.h>
 #include <linux/mutex.h>
 #include <linux/dmi.h>
 #include <linux/slab.h>
@@ -30,7 +31,12 @@
 #define POWER_METER_CAN_NOTIFY	(1 << 3)
 #define POWER_METER_IS_BATTERY	(1 << 8)
 #define UNKNOWN_HYSTERESIS	0xFFFFFFFF
-#define UNKNOWN_POWER		0xFFFFFFFF
+/*
+ * ACPI integers can either be 32-bit or 64-bit wide, so
+ * we have to check for both values.
+ */
+#define UNKNOWN_POWER_32	U32_MAX
+#define UNKNOWN_POWER_64	U64_MAX
 
 #define METER_NOTIFY_CONFIG	0x80
 #define METER_NOTIFY_TRIP	0x81
@@ -452,7 +458,7 @@ static int power_meter_read(struct device *dev, enum hwmon_sensor_types type,
 		ret = update_meter(res);
 		if (ret)
 			return ret;
-		if (res->power == UNKNOWN_POWER)
+		if (res->power == UNKNOWN_POWER_32 || res->power == UNKNOWN_POWER_64)
 			return -ENODATA;
 		*val = res->power * 1000;
 		break;
-- 
2.55.0