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Commit 411187fb authored by John Stultz's avatar John Stultz Committed by Linus Torvalds
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[PATCH] GTOD: persistent clock support 



Persistent clock support: do proper timekeeping across suspend/resume.

[bunk@stusta.de: cleanup]
Signed-off-by: default avatarJohn Stultz <johnstul@us.ibm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9f907c01

include/linux/hrtimer.h

+3 −0
Original line number Diff line number Diff line
@@ -146,6 +146,9 @@ extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, 
/* Soft interrupt function to run the hrtimer queues: */

extern void hrtimer_run_queues(void);



/* Resume notification */

void hrtimer_notify_resume(void);



/* Bootup initialization: */

extern void __init hrtimers_init(void);

include/linux/time.h

+1 −0
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ extern struct timespec xtime; 
extern struct timespec wall_to_monotonic;

extern seqlock_t xtime_lock __attribute__((weak));



extern unsigned long read_persistent_clock(void);

void timekeeping_init(void);



static inline unsigned long get_seconds(void)

kernel/hrtimer.c

+8 −0
Original line number Diff line number Diff line
@@ -291,6 +291,14 @@ static unsigned long ktime_divns(const ktime_t kt, s64 div) 
# define ktime_divns(kt, div)		(unsigned long)((kt).tv64 / (div))

#endif /* BITS_PER_LONG >= 64 */



/*

 * Timekeeping resumed notification

 */

void hrtimer_notify_resume(void)

{

	clock_was_set();

}



/*

 * Counterpart to lock_timer_base above:

 */

kernel/timer.c

+38 −1
Original line number Diff line number Diff line
@@ -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;

}