Input: make input_report_slot_state() return boolean

Let's make input_report_slot_state() return boolean representing whether
the contact is active or not. This will allow writing code like:

	if (input_mt_report_slot_state(input, obj->mt_tool,
					obj->type != RMI_2D_OBJECT_NONE) {

		input_event(sensor->input, EV_ABS, ABS_MT_POSITION_X, obj->x);
		input_event(sensor->input, EV_ABS, ABS_MT_POSITION_Y, obj->y);
		...
	}

instead of:

	input_mt_report_slot_state(input, obj->mt_tool,
				   obj->type != RMI_2D_OBJECT_NONE);
	if (obj->type != RMI_2D_OBJECT_NONE) {
		input_event(sensor->input, EV_ABS, ABS_MT_POSITION_X, obj->x);
		input_event(sensor->input, EV_ABS, ABS_MT_POSITION_Y, obj->y);
		...
	}
Reviewed-by: Henrik Rydberg <rydberg@bitmath.org>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redaht.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/input-mt.c

@@ -131,8 +131,10 @@ EXPORT_SYMBOL(input_mt_destroy_slots);
  * inactive, or if the tool type is changed, a new tracking id is
  * assigned to the slot. The tool type is only reported if the
  * corresponding absbit field is set.
+ *
+ * Returns true if contact is active.
  */
-void input_mt_report_slot_state(struct input_dev *dev,
+bool input_mt_report_slot_state(struct input_dev *dev,
 				unsigned int tool_type, bool active)
 {
 	struct input_mt *mt = dev->mt;
@@ -140,14 +142,14 @@ void input_mt_report_slot_state(struct input_dev *dev,
 	int id;
 
 	if (!mt)
-		return;
+		return false;
 
 	slot = &mt->slots[mt->slot];
 	slot->frame = mt->frame;
 
 	if (!active) {
 		input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
-		return;
+		return false;
 	}
 
 	id = input_mt_get_value(slot, ABS_MT_TRACKING_ID);
@@ -156,6 +158,8 @@ void input_mt_report_slot_state(struct input_dev *dev,
 
 	input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
 	input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
+
+	return true;
 }
 EXPORT_SYMBOL(input_mt_report_slot_state);
 

include/linux/input/mt.h

@@ -100,7 +100,7 @@ static inline bool input_is_mt_axis(int axis)
 	return axis == ABS_MT_SLOT || input_is_mt_value(axis);
 }
 
-void input_mt_report_slot_state(struct input_dev *dev,
+bool input_mt_report_slot_state(struct input_dev *dev,
 				unsigned int tool_type, bool active);
 
 void input_mt_report_finger_count(struct input_dev *dev, int count);