From a80b83b7b8456e9b475346c2e01d7e210883208c Mon Sep 17 00:00:00 2001 From: John Stultz Date: Fri, 3 Feb 2012 00:19:07 -0800 Subject: Input: add infrastructure for selecting clockid for event time stamps As noted by Arve and others, since wall time can jump backwards, it is difficult to use for input because one cannot determine if one event occurred before another or for how long a key was pressed. However, the timestamp field is part of the kernel ABI, and cannot be changed without possibly breaking existing users. This patch adds a new IOCTL that allows a clockid to be set in the evdev_client struct that will specify which time base to use for event timestamps (ie: CLOCK_MONOTONIC instead of CLOCK_REALTIME). For now we only support CLOCK_MONOTONIC and CLOCK_REALTIME, but in the future we could support other clockids if appropriate. The default remains CLOCK_REALTIME, so we don't change the ABI. Signed-off-by: John Stultz Reviewed-by: Daniel Kurtz Signed-off-by: Dmitry Torokhov --- kernel/time/timekeeping.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/time') diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 2b021b0e850..16947999475 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1140,6 +1140,8 @@ ktime_t ktime_get_monotonic_offset(void) } while (read_seqretry(&xtime_lock, seq)); return timespec_to_ktime(wtom); } +EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset); + /** * xtime_update() - advances the timekeeping infrastructure -- cgit v1.2.3-70-g09d2