hwmon: fix potential sensor registration fail if of_node is missing

It is not sufficient to check of_node in current device.
In some cases, this would cause the sensor registration to fail.

This patch looks for device's ancestors to find a valid of_node if any.

Fixes: d560168 ("hwmon: (core) New hwmon registration API")
Signed-off-by: Phinex Hung <phinex@realtek.com>
Link: https://lore.kernel.org/r/20230321060224.3819-1-phinex@realtek.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Author: phinexhung

drivers/hwmon/hwmon.c

@@ -757,6 +757,7 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 	struct hwmon_device *hwdev;
 	const char *label;
 	struct device *hdev;
+	struct device *tdev = dev;
 	int i, err, id;
 
 	/* Complain about invalid characters in hwmon name attribute */
@@ -826,7 +827,9 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 	hwdev->name = name;
 	hdev->class = &hwmon_class;
 	hdev->parent = dev;
-	hdev->of_node = dev ? dev->of_node : NULL;
+	while (tdev && !tdev->of_node)
+		tdev = tdev->parent;
+	hdev->of_node = tdev ? tdev->of_node : NULL;
 	hwdev->chip = chip;
 	dev_set_drvdata(hdev, drvdata);
 	dev_set_name(hdev, HWMON_ID_FORMAT, id);
@@ -838,7 +841,7 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
 
 	INIT_LIST_HEAD(&hwdev->tzdata);
 
-	if (dev && dev->of_node && chip && chip->ops->read &&
+	if (hdev->of_node && chip && chip->ops->read &&
 	    chip->info[0]->type == hwmon_chip &&
 	    (chip->info[0]->config[0] & HWMON_C_REGISTER_TZ)) {
 		err = hwmon_thermal_register_sensors(hdev);