Thermal: Introduce multiple cooling states support

This is because general active cooling devices, like fans,
may have multiple speeds, which can be mapped to different cooling states.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Valentin, Eduardo <eduardo.valentin@ti.com>

drivers/thermal/thermal_sys.c

@@ -1059,6 +1059,7 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
 	enum thermal_trip_type trip_type;
 	struct thermal_cooling_device_instance *instance;
 	struct thermal_cooling_device *cdev;
+	unsigned long cur_state, max_state;
 
 	mutex_lock(&tz->lock);
 
@@ -1098,10 +1099,17 @@ void thermal_zone_device_update(struct thermal_zone_device *tz)
 
 				cdev = instance->cdev;
 
+				cdev->ops->get_cur_state(cdev, &cur_state);
+				cdev->ops->get_max_state(cdev, &max_state);
+
 				if (temp >= trip_temp)
-					cdev->ops->set_cur_state(cdev, 1);
+					cur_state = cur_state < max_state ?
+						(cur_state + 1) : max_state;
 				else
-					cdev->ops->set_cur_state(cdev, 0);
+					cur_state = cur_state > 0 ?
+						(cur_state - 1) : 0;
+
+				cdev->ops->set_cur_state(cdev, cur_state);
 			}
 			break;
 		case THERMAL_TRIP_PASSIVE: