[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>
diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index fca9302..660d91d 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -146,6 +146,9 @@
/* 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);
diff --git a/include/linux/time.h b/include/linux/time.h
index eceb1a5..8ea8dea 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -92,6 +92,7 @@
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)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 80666f6..c0fdb9b 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -292,6 +292,14 @@
#endif /* BITS_PER_LONG >= 64 */
/*
+ * Timekeeping resumed notification
+ */
+void hrtimer_notify_resume(void)
+{
+ clock_was_set();
+}
+
+/*
* Counterpart to lock_timer_base above:
*/
static inline
diff --git a/kernel/timer.c b/kernel/timer.c
index 4f9cc2a..8f4bf1e 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -878,12 +878,27 @@
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 @@
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_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 @@
write_seqlock_irqsave(&xtime_lock, flags);
timekeeping_suspended = 1;
+ timekeeping_suspend_time = read_persistent_clock();
write_sequnlock_irqrestore(&xtime_lock, flags);
return 0;
}