[PATCH 4/7] power: supply: core: hide unused HWMON labels

["Michał Mirosław" <mirq-linux@rere.qmqm.pl>]

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>
---
 drivers/power/supply/power_supply_hwmon.c | 43 +++++++++++++++++++++--
 1 file changed, 40 insertions(+), 3 deletions(-)

diff --git a/drivers/power/supply/power_supply_hwmon.c b/drivers/power/supply/power_supply_hwmon.c
index 83318a21fb52..118d73a2ab4a 100644
--- a/drivers/power/supply/power_supply_hwmon.c
+++ b/drivers/power/supply/power_supply_hwmon.c
@@ -103,6 +103,40 @@ static bool power_supply_hwmon_is_a_label(enum hwmon_sensor_types type,
 	return type == hwmon_temp && attr == hwmon_temp_label;
 }
 
+static bool power_supply_hwmon_has_property(
+	const struct power_supply_hwmon *psyhw,
+	enum hwmon_sensor_types type, u32 attr, int channel)
+{
+	int prop = power_supply_hwmon_to_property(type, attr, channel);
+
+	return prop >= 0 && test_bit(prop, psyhw->props);
+}
+
+static bool power_supply_hwmon_has_input(
+	const struct power_supply_hwmon *psyhw,
+	enum hwmon_sensor_types type, int channel)
+{
+	static const enum hwmon_temp_attributes temp_attrs[] = {
+		hwmon_temp_input,
+		hwmon_temp_min, hwmon_temp_max,
+		hwmon_temp_min_alarm, hwmon_temp_max_alarm,
+	};
+	size_t i;
+
+	switch (type) {
+	case hwmon_temp:
+		for (i = 0; i < ARRAY_SIZE(temp_attrs); ++i)
+			if (power_supply_hwmon_has_property(psyhw, type,
+					temp_attrs[i], channel))
+				return true;
+		break;
+	default:
+		break;
+	}
+
+	return false;
+}
+
 static bool power_supply_hwmon_is_writable(enum hwmon_sensor_types type,
 					   u32 attr)
 {
@@ -129,9 +163,12 @@ 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))
-- 
2.20.1