Input: bcm5974 - add quad-finger tapping

The integrated button on the new unibody Macbooks presents a need to
report explicit four-finger actions. Evidently, the finger pressing
the button is also touching the trackpad, so in order to fully support
three-finger actions, the driver must be able to report four-finger
actions. This patch adds a new button, BTN_TOOL_QUADTAP, which
achieves this.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/mouse/bcm5974.c

@@ -258,6 +258,7 @@ static void setup_events_to_report(struct input_dev *input_dev,
 	__set_bit(BTN_TOOL_FINGER, input_dev->keybit);
 	__set_bit(BTN_TOOL_DOUBLETAP, input_dev->keybit);
 	__set_bit(BTN_TOOL_TRIPLETAP, input_dev->keybit);
+	__set_bit(BTN_TOOL_QUADTAP, input_dev->keybit);
 	__set_bit(BTN_LEFT, input_dev->keybit);
 }
 
@@ -329,7 +330,8 @@ static int report_tp_state(struct bcm5974 *dev, int size)
 	input_report_key(input, BTN_TOUCH, dev->fingers > 0);
 	input_report_key(input, BTN_TOOL_FINGER, dev->fingers == 1);
 	input_report_key(input, BTN_TOOL_DOUBLETAP, dev->fingers == 2);
-	input_report_key(input, BTN_TOOL_TRIPLETAP, dev->fingers > 2);
+	input_report_key(input, BTN_TOOL_TRIPLETAP, dev->fingers == 3);
+	input_report_key(input, BTN_TOOL_QUADTAP, dev->fingers > 3);
 
 	input_report_abs(input, ABS_PRESSURE, abs_p);
 	input_report_abs(input, ABS_TOOL_WIDTH, abs_w);

include/linux/input.h

@@ -445,6 +445,7 @@ struct input_absinfo {
 #define BTN_STYLUS2		0x14c
 #define BTN_TOOL_DOUBLETAP	0x14d
 #define BTN_TOOL_TRIPLETAP	0x14e
+#define BTN_TOOL_QUADTAP	0x14f	/* Four fingers on trackpad */
 
 #define BTN_WHEEL		0x150
 #define BTN_GEAR_DOWN		0x150