power: supply: core: hide unused HWMON labels

Currently HWMON emulation shows all labels (temp and ambient temp)
regardless if power supply supports reading the values. Check that at
least one property is enabled for each label.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/power_supply_hwmon.c

@@ -98,6 +98,39 @@ static bool power_supply_hwmon_is_a_label(enum hwmon_sensor_types type,
 	return type == hwmon_temp && attr == hwmon_temp_label;
 }
 
+struct hwmon_type_attr_list {
+	const u32 *attrs;
+	size_t n_attrs;
+};
+
+static const u32 ps_temp_attrs[] = {
+	hwmon_temp_input,
+	hwmon_temp_min, hwmon_temp_max,
+	hwmon_temp_min_alarm, hwmon_temp_max_alarm,
+};
+
+static const struct hwmon_type_attr_list ps_type_attrs[hwmon_max] = {
+	[hwmon_temp] = { ps_temp_attrs, ARRAY_SIZE(ps_temp_attrs) },
+};
+
+static bool power_supply_hwmon_has_input(
+	const struct power_supply_hwmon *psyhw,
+	enum hwmon_sensor_types type, int channel)
+{
+	const struct hwmon_type_attr_list *attr_list = &ps_type_attrs[type];
+	size_t i;
+
+	for (i = 0; i < attr_list->n_attrs; ++i) {
+		int prop = power_supply_hwmon_to_property(type,
+			attr_list->attrs[i], channel);
+
+		if (prop >= 0 && test_bit(prop, psyhw->props))
+			return true;
+	}
+
+	return false;
+}
+
 static bool power_supply_hwmon_is_writable(enum hwmon_sensor_types type,
 					   u32 attr)
 {
@@ -124,9 +157,12 @@ static umode_t power_supply_hwmon_is_visible(const void *data,
 	const struct power_supply_hwmon *psyhw = data;
 	int prop;
 
-
-	if (power_supply_hwmon_is_a_label(type, attr))
-		return 0444;
+	if (power_supply_hwmon_is_a_label(type, attr)) {
+		if (power_supply_hwmon_has_input(psyhw, type, channel))
+			return 0444;
+		else
+			return 0;
+	}
 
 	prop = power_supply_hwmon_to_property(type, attr, channel);
 	if (prop < 0 || !test_bit(prop, psyhw->props))