From 411187fb05cd11676b0979d9fbf3291db69dbce2 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Fri, 16 Feb 2007 01:27:30 -0800 Subject: [PATCH] GTOD: persistent clock support Persistent clock support: do proper timekeeping across suspend/resume. [bunk@stusta.de: cleanup] Signed-off-by: John Stultz Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Cc: Roman Zippel Cc: Adrian Bunk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/timer.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) (limited to 'kernel/timer.c') 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; } -- cgit v1.2.3-59-g8ed1b