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Commit 65516f8a authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Thomas Gleixner
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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: default avatarMartin 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: default avatarThomas Gleixner <tglx@linutronix.de>
parent d1748302

include/linux/clockchips.h

+7 −3
Original line number Diff line number Diff line
@@ -45,20 +45,22 @@ enum clock_event_nofitiers { 
 */

#define CLOCK_EVT_FEAT_PERIODIC		0x000001

#define CLOCK_EVT_FEAT_ONESHOT		0x000002

#define CLOCK_EVT_FEAT_KTIME		0x000004

/*

 * x86(64) specific misfeatures:

 *

 * - Clockevent source stops in C3 State and needs broadcast support.

 * - Local APIC timer is used as a dummy device.

 */

#define CLOCK_EVT_FEAT_C3STOP		0x000004

#define CLOCK_EVT_FEAT_DUMMY		0x000008

#define CLOCK_EVT_FEAT_C3STOP		0x000008

#define CLOCK_EVT_FEAT_DUMMY		0x000010



/**

 * struct clock_event_device - clock event device descriptor

 * @event_handler:	Assigned by the framework to be called by the low

 *			level handler of the event source

 * @set_next_event:	set next event function

 * @set_next_event:	set next event function using a clocksource delta

 * @set_next_ktime:	set next event function using a direct ktime value

 * @next_event:		local storage for the next event in oneshot mode

 * @max_delta_ns:	maximum delta value in ns

 * @min_delta_ns:	minimum delta value in ns
@@ -81,6 +83,8 @@ struct clock_event_device { 
	void			(*event_handler)(struct clock_event_device *);

	int			(*set_next_event)(unsigned long evt,

						  struct clock_event_device *);

	int			(*set_next_ktime)(ktime_t expires,

						  struct clock_event_device *);

	ktime_t			next_event;

	u64			max_delta_ns;

	u64			min_delta_ns;

kernel/time/clockevents.c

+4 −0
Original line number Diff line number Diff line
@@ -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;