thermal: expose thermal_zone_get_temp API

This patch exports the thermal_zone_get_temp API so that driver
writers can fetch temperature of thermal zones managed by other
drivers.

Acked-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

drivers/thermal/thermal_core.c

@@ -369,16 +369,28 @@ static void handle_thermal_trip(struct thermal_zone_device *tz, int trip)
 	monitor_thermal_zone(tz);
 }
 
-static int thermal_zone_get_temp(struct thermal_zone_device *tz,
-				unsigned long *temp)
+/**
+ * thermal_zone_get_temp() - returns its the temperature of thermal zone
+ * @tz: a valid pointer to a struct thermal_zone_device
+ * @temp: a valid pointer to where to store the resulting temperature.
+ *
+ * When a valid thermal zone reference is passed, it will fetch its
+ * temperature and fill @temp.
+ *
+ * Return: On success returns 0, an error code otherwise
+ */
+int thermal_zone_get_temp(struct thermal_zone_device *tz, unsigned long *temp)
 {
-	int ret = 0;
+	int ret = -EINVAL;
 #ifdef CONFIG_THERMAL_EMULATION
 	int count;
 	unsigned long crit_temp = -1UL;
 	enum thermal_trip_type type;
 #endif
 
+	if (IS_ERR_OR_NULL(tz))
+		goto exit;
+
 	mutex_lock(&tz->lock);
 
 	ret = tz->ops->get_temp(tz, temp);
@@ -402,8 +414,10 @@ static int thermal_zone_get_temp(struct thermal_zone_device *tz,
 skip_emul:
 #endif
 	mutex_unlock(&tz->lock);
+exit:
 	return ret;
 }
+EXPORT_SYMBOL_GPL(thermal_zone_get_temp);
 
 static void update_temperature(struct thermal_zone_device *tz)
 {

include/linux/thermal.h

@@ -240,6 +240,7 @@ struct thermal_cooling_device *thermal_cooling_device_register(char *, void *,
 		const struct thermal_cooling_device_ops *);
 void thermal_cooling_device_unregister(struct thermal_cooling_device *);
 struct thermal_zone_device *thermal_zone_get_zone_by_name(const char *name);
+int thermal_zone_get_temp(struct thermal_zone_device *tz, unsigned long *temp);
 
 int get_tz_trend(struct thermal_zone_device *, int);
 struct thermal_instance *get_thermal_instance(struct thermal_zone_device *,