thermal: core: Introduce .trip_crossed() callback for thermal governors

Introduce a new thermal governor callback called .trip_crossed()
that will be invoked whenever a trip point is crossed by the zone
temperature, either on the way up or on the way down.

The trip crossing direction information will be passed to it and if
multiple trips are crossed in the same direction during one thermal zone
update, the new callback will be invoked for them in temperature order,
either ascending or descending, depending on the trip crossing
direction.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

drivers/thermal/thermal_core.c

@@ -302,11 +302,21 @@ static void monitor_thermal_zone(struct thermal_zone_device *tz)
 		thermal_zone_device_set_polling(tz, tz->polling_delay_jiffies);
 }
 
+static struct thermal_governor *thermal_get_tz_governor(struct thermal_zone_device *tz)
+{
+	if (tz->governor)
+		return tz->governor;
+
+	return def_governor;
+}
+
 static void handle_non_critical_trips(struct thermal_zone_device *tz,
 				      const struct thermal_trip *trip)
 {
-	tz->governor ? tz->governor->throttle(tz, trip) :
-		       def_governor->throttle(tz, trip);
+	struct thermal_governor *governor = thermal_get_tz_governor(tz);
+
+	if (governor->throttle)
+		governor->throttle(tz, trip);
 }
 
 void thermal_governor_update_tz(struct thermal_zone_device *tz,
@@ -470,6 +480,7 @@ static int thermal_trip_notify_cmp(void *ascending, const struct list_head *a,
 void __thermal_zone_device_update(struct thermal_zone_device *tz,
 				  enum thermal_notify_event event)
 {
+	struct thermal_governor *governor = thermal_get_tz_governor(tz);
 	struct thermal_trip_desc *td;
 	LIST_HEAD(way_down_list);
 	LIST_HEAD(way_up_list);
@@ -493,12 +504,16 @@ void __thermal_zone_device_update(struct thermal_zone_device *tz,
 	list_for_each_entry(td, &way_up_list, notify_list_node) {
 		thermal_notify_tz_trip_up(tz, &td->trip);
 		thermal_debug_tz_trip_up(tz, &td->trip);
+		if (governor->trip_crossed)
+			governor->trip_crossed(tz, &td->trip, true);
 	}
 
 	list_sort(NULL, &way_down_list, thermal_trip_notify_cmp);
 	list_for_each_entry(td, &way_down_list, notify_list_node) {
 		thermal_notify_tz_trip_down(tz, &td->trip);
 		thermal_debug_tz_trip_down(tz, &td->trip);
+		if (governor->trip_crossed)
+			governor->trip_crossed(tz, &td->trip, false);
 	}
 
 	monitor_thermal_zone(tz);

drivers/thermal/thermal_core.h

@@ -30,6 +30,7 @@ struct thermal_trip_desc {
  *		otherwise it fails.
  * @unbind_from_tz:	callback called when a governor is unbound from a
  *			thermal zone.
+ * @trip_crossed:	called for trip points that have just been crossed
  * @throttle:	callback called for every trip point even if temperature is
  *		below the trip point temperature
  * @update_tz:	callback called when thermal zone internals have changed, e.g.
@@ -40,6 +41,9 @@ struct thermal_governor {
 	const char *name;
 	int (*bind_to_tz)(struct thermal_zone_device *tz);
 	void (*unbind_from_tz)(struct thermal_zone_device *tz);
+	void (*trip_crossed)(struct thermal_zone_device *tz,
+			     const struct thermal_trip *trip,
+			     bool crossed_up);
 	int (*throttle)(struct thermal_zone_device *tz,
 			const struct thermal_trip *trip);
 	void (*update_tz)(struct thermal_zone_device *tz,