Input: add the ABS_MT_PRESSURE event

For pressure-based multi-touch devices, a direct way to send sensor
intensity data per finger is needed. This patch adds the ABS_MT_PRESSURE
event to the MT protocol.
Requested-by: NYoonyoung Shim <jy0922.shim@samsung.com>
Requested-by: NMika Kuoppala <mika.kuoppala@nokia.com>
Requested-by: NPeter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: NHenrik Rydberg <rydberg@euromail.se>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

drivers/input/input.c

@@ -46,6 +46,7 @@ static unsigned int input_abs_bypass_init_data[] __initdata = {
 	ABS_MT_TOOL_TYPE,
 	ABS_MT_BLOB_ID,
 	ABS_MT_TRACKING_ID,
+	ABS_MT_PRESSURE,
 	0
 };
 static unsigned long input_abs_bypass[BITS_TO_LONGS(ABS_CNT)];

include/linux/input.h

@@ -660,6 +660,7 @@ struct input_absinfo {
 #define ABS_MT_TOOL_TYPE	0x37	/* Type of touching device */
 #define ABS_MT_BLOB_ID		0x38	/* Group a set of packets as a blob */
 #define ABS_MT_TRACKING_ID	0x39	/* Unique ID of initiated contact */
+#define ABS_MT_PRESSURE		0x3a	/* Pressure on contact area */
 
 #define ABS_MAX			0x3f
 #define ABS_CNT			(ABS_MAX+1)