diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/ntp.c | 59 |
1 files changed, 56 insertions, 3 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index b5e352597cbb..cd91237dbfe3 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -10,6 +10,7 @@ #include <linux/mm.h> #include <linux/time.h> +#include <linux/timer.h> #include <linux/timex.h> #include <linux/jiffies.h> #include <linux/hrtimer.h> @@ -175,12 +176,64 @@ u64 current_tick_length(void) return tick_length; } +#ifdef CONFIG_GENERIC_CMOS_UPDATE -void __attribute__ ((weak)) notify_arch_cmos_timer(void) +/* Disable the cmos update - used by virtualization and embedded */ +int no_sync_cmos_clock __read_mostly; + +static void sync_cmos_clock(unsigned long dummy); + +static DEFINE_TIMER(sync_cmos_timer, sync_cmos_clock, 0, 0); + +static void sync_cmos_clock(unsigned long dummy) +{ + struct timespec now, next; + int fail = 1; + + /* + * If we have an externally synchronized Linux clock, then update + * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be + * called as close as possible to 500 ms before the new second starts. + * This code is run on a timer. If the clock is set, that timer + * may not expire at the correct time. Thus, we adjust... + */ + if (!ntp_synced()) + /* + * Not synced, exit, do not restart a timer (if one is + * running, let it run out). + */ + return; + + getnstimeofday(&now); + if (abs(xtime.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) + fail = update_persistent_clock(now); + + next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec; + if (next.tv_nsec <= 0) + next.tv_nsec += NSEC_PER_SEC; + + if (!fail) + next.tv_sec = 659; + else + next.tv_sec = 0; + + if (next.tv_nsec >= NSEC_PER_SEC) { + next.tv_sec++; + next.tv_nsec -= NSEC_PER_SEC; + } + mod_timer(&sync_cmos_timer, jiffies + timespec_to_jiffies(&next)); +} + +static void notify_cmos_timer(void) { - return; + if (no_sync_cmos_clock) + mod_timer(&sync_cmos_timer, jiffies + 1); } +#else +static inline void notify_cmos_timer(void) { } +#endif + /* adjtimex mainly allows reading (and writing, if superuser) of * kernel time-keeping variables. used by xntpd. */ @@ -345,6 +398,6 @@ leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0) txc->stbcnt = 0; write_sequnlock_irq(&xtime_lock); do_gettimeofday(&txc->time); - notify_arch_cmos_timer(); + notify_cmos_timer(); return(result); } |