[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>
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@ -146,6 +146,9 @@ extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
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/* Soft interrupt function to run the hrtimer queues: */
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extern void hrtimer_run_queues(void);
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/* Resume notification */
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void hrtimer_notify_resume(void);
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/* Bootup initialization: */
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extern void __init hrtimers_init(void);
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@ -92,6 +92,7 @@ extern struct timespec xtime;
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extern struct timespec wall_to_monotonic;
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extern seqlock_t xtime_lock __attribute__((weak));
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extern unsigned long read_persistent_clock(void);
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void timekeeping_init(void);
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static inline unsigned long get_seconds(void)
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@ -291,6 +291,14 @@ static unsigned long ktime_divns(const ktime_t kt, s64 div)
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# define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))
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#endif /* BITS_PER_LONG >= 64 */
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/*
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* Timekeeping resumed notification
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*/
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void hrtimer_notify_resume(void)
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{
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clock_was_set();
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}
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/*
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* Counterpart to lock_timer_base above:
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*/
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@ -878,12 +878,27 @@ int timekeeping_is_continuous(void)
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return ret;
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}
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/**
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* read_persistent_clock - Return time in seconds from the persistent clock.
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*
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* Weak dummy function for arches that do not yet support it.
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* Returns seconds from epoch using the battery backed persistent clock.
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* Returns zero if unsupported.
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*
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* XXX - Do be sure to remove it once all arches implement it.
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*/
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unsigned long __attribute__((weak)) read_persistent_clock(void)
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{
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return 0;
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}
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/*
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* timekeeping_init - Initializes the clocksource and common timekeeping values
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*/
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void __init timekeeping_init(void)
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{
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unsigned long flags;
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unsigned long sec = read_persistent_clock();
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write_seqlock_irqsave(&xtime_lock, flags);
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@ -893,11 +908,20 @@ void __init timekeeping_init(void)
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clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
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clock->cycle_last = clocksource_read(clock);
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xtime.tv_sec = sec;
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xtime.tv_nsec = 0;
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set_normalized_timespec(&wall_to_monotonic,
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-xtime.tv_sec, -xtime.tv_nsec);
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write_sequnlock_irqrestore(&xtime_lock, flags);
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}
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/* flag for if timekeeping is suspended */
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static int timekeeping_suspended;
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/* time in seconds when suspend began */
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static unsigned long timekeeping_suspend_time;
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/**
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* timekeeping_resume - Resumes the generic timekeeping subsystem.
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* @dev: unused
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@ -909,13 +933,25 @@ static int timekeeping_suspended;
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static int timekeeping_resume(struct sys_device *dev)
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{
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unsigned long flags;
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unsigned long now = read_persistent_clock();
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write_seqlock_irqsave(&xtime_lock, flags);
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/* restart the last cycle value */
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if (now && (now > timekeeping_suspend_time)) {
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unsigned long sleep_length = now - timekeeping_suspend_time;
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xtime.tv_sec += sleep_length;
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wall_to_monotonic.tv_sec -= sleep_length;
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}
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/* re-base the last cycle value */
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clock->cycle_last = clocksource_read(clock);
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clock->error = 0;
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timekeeping_suspended = 0;
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write_sequnlock_irqrestore(&xtime_lock, flags);
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touch_softlockup_watchdog();
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hrtimer_notify_resume();
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return 0;
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}
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@ -925,6 +961,7 @@ static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
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write_seqlock_irqsave(&xtime_lock, flags);
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timekeeping_suspended = 1;
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timekeeping_suspend_time = read_persistent_clock();
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write_sequnlock_irqrestore(&xtime_lock, flags);
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return 0;
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}
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