clocksource: add enable() and disable() callbacks

[deliverable/linux.git] / kernel / time / timekeeping.c

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index fa05e88aa76f36af2dc5cb0cc26f737466d0a423..687dff49f6e7da5ec92199f6bbae08de57e5ba43 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -46,6 +46,9 @@ struct timespec xtime __attribute__ ((aligned (16)));
 struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
 static unsigned long total_sleep_time;         /* seconds */
 
+/* flag for if timekeeping is suspended */
+int __read_mostly timekeeping_suspended;
+
 static struct timespec xtime_cache __attribute__ ((aligned (16)));
 void update_xtime_cache(u64 nsec)
 {
@@ -92,6 +95,8 @@ void getnstimeofday(struct timespec *ts)
        unsigned long seq;
        s64 nsecs;
 
+       WARN_ON(timekeeping_suspended);
+
        do {
                seq = read_seqbegin(&xtime_lock);
 
@@ -177,7 +182,7 @@ EXPORT_SYMBOL(do_settimeofday);
  */
 static void change_clocksource(void)
 {
-       struct clocksource *new;
+       struct clocksource *new, *old;
 
        new = clocksource_get_next();
 
@@ -186,11 +191,16 @@ static void change_clocksource(void)
 
        clocksource_forward_now();
 
-       new->raw_time = clock->raw_time;
+       if (clocksource_enable(new))
+               return;
 
+       new->raw_time = clock->raw_time;
+       old = clock;
        clock = new;
+       clocksource_disable(old);
+
        clock->cycle_last = 0;
-       clock->cycle_last = clocksource_read(new);
+       clock->cycle_last = clocksource_read(clock);
        clock->error = 0;
        clock->xtime_nsec = 0;
        clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
@@ -287,6 +297,7 @@ void __init timekeeping_init(void)
        ntp_init();
 
        clock = clocksource_get_next();
+       clocksource_enable(clock);
        clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
        clock->cycle_last = clocksource_read(clock);
 
@@ -299,8 +310,6 @@ void __init timekeeping_init(void)
        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;