Register the mt7915 phy as a thermal zone sensor using
devm_thermal_of_zone_register() so that device tree thermal-zones
nodes can reference the Wi-Fi chip as a temperature source. This
allows the kernel thermal governor to control external cooling
devices such as PWM fans based on Wi-Fi chip temperature.

Registration is non-fatal: -ENODEV is returned when no
thermal-sensors DT property references this device, which is the
expected case on platforms without a thermal zone configured.

Signed-off-by: Ryan Leung <untilscour@protonmail.com>
---
 .../net/wireless/mediatek/mt76/mt7915/init.c  | 29 +++++++++++++++++++
 .../wireless/mediatek/mt76/mt7915/mt7915.h    |  1 +
 2 files changed, 30 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
index 250c2d2479b0..817a9045e326 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
@@ -177,6 +177,25 @@ static const struct thermal_cooling_device_ops mt7915_thermal_ops = {
 	.set_cur_state = mt7915_thermal_set_cur_throttle_state,
 };
 
+static int mt7915_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
+{
+	struct mt7915_phy *phy = thermal_zone_device_priv(tz);
+	int val;
+
+	mutex_lock(&phy->dev->mt76.mutex);
+	val = mt7915_mcu_get_temperature(phy);
+	mutex_unlock(&phy->dev->mt76.mutex);
+	if (val < 0)
+		return val;
+
+	*temp = val * 1000;
+	return 0;
+}
+
+static const struct thermal_zone_device_ops mt7915_tz_ops = {
+	.get_temp = mt7915_thermal_get_temp,
+};
+
 static void mt7915_unregister_thermal(struct mt7915_phy *phy)
 {
 	struct wiphy *wiphy = phy->mt76->hw->wiphy;
@@ -213,6 +232,16 @@ static int mt7915_thermal_init(struct mt7915_phy *phy)
 	phy->throttle_temp[MT7915_CRIT_TEMP_IDX] = MT7915_CRIT_TEMP;
 	phy->throttle_temp[MT7915_MAX_TEMP_IDX] = MT7915_MAX_TEMP;
 
+	phy->tzone = devm_thermal_of_zone_register(phy->dev->mt76.dev, 0, phy,
+						   &mt7915_tz_ops);
+	if (IS_ERR(phy->tzone)) {
+		if (PTR_ERR(phy->tzone) != -ENODEV)
+			dev_warn(phy->dev->mt76.dev,
+				 "failed to register thermal zone: %ld\n",
+				 PTR_ERR(phy->tzone));
+		phy->tzone = NULL;
+	}
+
 	if (!IS_REACHABLE(CONFIG_HWMON))
 		return 0;
 
diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h b/drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h
index bf1d915a3ca2..92e0f9f0169c 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h
@@ -205,6 +205,7 @@ struct mt7915_phy {
 
 	struct ieee80211_vif *monitor_vif;
 
+	struct thermal_zone_device *tzone;
 	struct thermal_cooling_device *cdev;
 	u8 cdev_state;
 	u8 throttle_state;
-- 
2.43.0