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: Yoonyoung Shim <jy0922.shim@samsung.com>
Requested-by: Mika Kuoppala <mika.kuoppala@nokia.com>
Requested-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/include/linux/input.h b/include/linux/input.h
index 7be8a65..735ceaf 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -660,6 +660,7 @@
 #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)