clockevents: Add direct ktime programming function

There is at least one architecture (s390) with a sane clockevent device
that can be programmed with the equivalent of a ktime. No need to create
a delta against the current time, the ktime can be used directly.

A new clock device function 'set_next_ktime' is introduced that is called
with the unmodified ktime for the timer if the clock event device has the 
CLOCK_EVT_FEAT_KTIME bit set.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: john stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/20110823133142.815350967@de.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Martin Schwidefsky 2011-08-23 15:29:43 +02:00 committed by Thomas Gleixner
parent d1748302f7
commit 65516f8a7c
2 changed files with 11 additions and 3 deletions

View file

@ -216,6 +216,10 @@ int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
return 0;
/* Shortcut for clockevent devices that can deal with ktime. */
if (dev->features & CLOCK_EVT_FEAT_KTIME)
return dev->set_next_ktime(expires, dev);
delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
if (delta <= 0)
return force ? clockevents_program_min_delta(dev) : -ETIME;