Input: introduce EV_MSC Timestamp

Some devices provides the actual timestamp (hid_dg_scan_time in win8 ones)
computed by the hardware itself. This value is global to the frame and is
not specific to the multitouch protocol.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Reviewed-by: Henrik Rydberg <rydberg@euromail.se>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

2 files changed, 12 insertions, 0 deletions

diff --git a/Documentation/input/event-codes.txt b/Documentation/input/event-codes.txt
index 53305bd08182..f1ea2c69648d 100644
--- a/Documentation/input/event-codes.txt
+++ b/Documentation/input/event-codes.txt
@@ -196,6 +196,17 @@ EV_MSC:
 EV_MSC events are used for input and output events that do not fall under other
 categories.
 
+A few EV_MSC codes have special meaning:
+
+* MSC_TIMESTAMP:
+  - Used to report the number of microseconds since the last reset. This event
+    should be coded as an uint32 value, which is allowed to wrap around with
+    no special consequence. It is assumed that the time difference between two
+    consecutive events is reliable on a reasonable time scale (hours).
+    A reset to zero can happen, in which case the time since the last event is
+    unknown.  If the device does not provide this information, the driver must
+    not provide it to user space.
+
 EV_LED:
 ----------
 EV_LED events are used for input and output to set and query the state of
diff --git a/include/uapi/linux/input.h b/include/uapi/linux/input.h
index 558828590a69..935119c698ac 100644
--- a/include/uapi/linux/input.h
+++ b/include/uapi/linux/input.h
@@ -851,6 +851,7 @@ struct input_keymap_entry {
 #define MSC_GESTURE             0x02
 #define MSC_RAW                 0x03
 #define MSC_SCAN                0x04
+#define MSC_TIMESTAMP           0x05
 #define MSC_MAX                 0x07
 #define MSC_CNT                 (MSC_MAX+1)