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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2011-08-23 15:29:43 +0200
committerThomas Gleixner <tglx@linutronix.de>2011-09-08 11:10:56 +0200
commit65516f8a7c2028381f0dae4c16ddb621c96158cc (patch)
tree1f6192832c77e25499331b074398e165c1220197
parentd1748302f70be7469809809283fe164156a34231 (diff)
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>
-rw-r--r--include/linux/clockchips.h10
-rw-r--r--kernel/time/clockevents.c4
2 files changed, 11 insertions, 3 deletions
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 39bb050bdbb2..81e803e90aa4 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -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;
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 713ef94eceef..1ecd6ba36d6c 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -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;