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authorJohn Stultz <johnstul@us.ibm.com>2007-02-16 12:27:30 +0300
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-16 19:13:57 +0300
commit411187fb05cd11676b0979d9fbf3291db69dbce2 (patch)
tree6202ca36868ab47edf737de81c7b7c4841228ab3 /kernel/timer.c
parent9f907c0144496e464bd5ed5a99a51227d63a9c0b (diff)
downloadlinux-411187fb05cd11676b0979d9fbf3291db69dbce2.tar.xz
[PATCH] GTOD: persistent clock support
Persistent clock support: do proper timekeeping across suspend/resume. [bunk@stusta.de: cleanup] Signed-off-by: John Stultz <johnstul@us.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/timer.c')
-rw-r--r--kernel/timer.c39
1 files changed, 38 insertions, 1 deletions
diff --git a/kernel/timer.c b/kernel/timer.c
index 4f9cc2a48beb..8f4bf1e6a3ed 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -878,12 +878,27 @@ int timekeeping_is_continuous(void)
return ret;
}
+/**
+ * read_persistent_clock - Return time in seconds from the persistent clock.
+ *
+ * Weak dummy function for arches that do not yet support it.
+ * Returns seconds from epoch using the battery backed persistent clock.
+ * Returns zero if unsupported.
+ *
+ * XXX - Do be sure to remove it once all arches implement it.
+ */
+unsigned long __attribute__((weak)) read_persistent_clock(void)
+{
+ return 0;
+}
+
/*
* timekeeping_init - Initializes the clocksource and common timekeeping values
*/
void __init timekeeping_init(void)
{
unsigned long flags;
+ unsigned long sec = read_persistent_clock();
write_seqlock_irqsave(&xtime_lock, flags);
@@ -893,11 +908,20 @@ void __init timekeeping_init(void)
clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
clock->cycle_last = clocksource_read(clock);
+ xtime.tv_sec = sec;
+ xtime.tv_nsec = 0;
+ set_normalized_timespec(&wall_to_monotonic,
+ -xtime.tv_sec, -xtime.tv_nsec);
+
write_sequnlock_irqrestore(&xtime_lock, flags);
}
+/* flag for if timekeeping is suspended */
static int timekeeping_suspended;
+/* time in seconds when suspend began */
+static unsigned long timekeeping_suspend_time;
+
/**
* timekeeping_resume - Resumes the generic timekeeping subsystem.
* @dev: unused
@@ -909,13 +933,25 @@ static int timekeeping_suspended;
static int timekeeping_resume(struct sys_device *dev)
{
unsigned long flags;
+ unsigned long now = read_persistent_clock();
write_seqlock_irqsave(&xtime_lock, flags);
- /* restart the last cycle value */
+
+ if (now && (now > timekeeping_suspend_time)) {
+ unsigned long sleep_length = now - timekeeping_suspend_time;
+
+ xtime.tv_sec += sleep_length;
+ wall_to_monotonic.tv_sec -= sleep_length;
+ }
+ /* re-base the last cycle value */
clock->cycle_last = clocksource_read(clock);
clock->error = 0;
timekeeping_suspended = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
+
+ touch_softlockup_watchdog();
+ hrtimer_notify_resume();
+
return 0;
}
@@ -925,6 +961,7 @@ static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
write_seqlock_irqsave(&xtime_lock, flags);
timekeeping_suspended = 1;
+ timekeeping_suspend_time = read_persistent_clock();
write_sequnlock_irqrestore(&xtime_lock, flags);
return 0;
}