This is how it's done on i386, and it makes one less bit of code to trim from main_timer_handler() when converting to clockevents. Signed-off-by: Chris Wright Cc: Thomas Gleixner Cc: Ingo Molnar Cc: john stultz Cc: Andi Kleen --- arch/x86_64/kernel/time.c | 68 +++++++++++++++++++++++++++++++++++----------- 1 file changed, 52 insertions(+), 16 deletions(-) --- linus-2.6.orig/arch/x86_64/kernel/time.c +++ linus-2.6/arch/x86_64/kernel/time.c @@ -81,8 +81,9 @@ EXPORT_SYMBOL(profile_pc); * sheet for details. */ -static void set_rtc_mmss(unsigned long nowtime) +static int set_rtc_mmss(unsigned long nowtime) { + int retval = 0; int real_seconds, real_minutes, cmos_minutes; unsigned char control, freq_select; @@ -122,6 +123,7 @@ static void set_rtc_mmss(unsigned long n if (abs(real_minutes - cmos_minutes) >= 30) { printk(KERN_WARNING "time.c: can't update CMOS clock " "from %d to %d\n", cmos_minutes, real_minutes); + retval = -1; } else { BIN_TO_BCD(real_seconds); BIN_TO_BCD(real_minutes); @@ -141,12 +143,60 @@ static void set_rtc_mmss(unsigned long n CMOS_WRITE(freq_select, RTC_FREQ_SELECT); spin_unlock(&rtc_lock); + + return retval; +} + +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 - 500000000) <= tick_nsec / 2) + fail = set_rtc_mmss(now.tv_sec); + + next.tv_nsec = 500000000 - 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)); } +void notify_arch_cmos_timer(void) +{ + mod_timer(&sync_cmos_timer, jiffies + 1); +} void main_timer_handler(void) { - static unsigned long rtc_update = 0; /* * Here we are in the timer irq handler. We have irqs locally disabled (so we * don't need spin_lock_irqsave()) but we don't know if the timer_bh is running @@ -174,20 +224,6 @@ void main_timer_handler(void) if (!using_apic_timer) smp_local_timer_interrupt(); -/* - * If we have an externally synchronized Linux clock, then update CMOS clock - * accordingly every ~11 minutes. set_rtc_mmss() will be called in the jiffy - * closest to exactly 500 ms before the next second. If the update fails, we - * don't care, as it'll be updated on the next turn, and the problem (time way - * off) isn't likely to go away much sooner anyway. - */ - - if (ntp_synced() && xtime.tv_sec > rtc_update && - abs(xtime.tv_nsec - 500000000) <= tick_nsec / 2) { - set_rtc_mmss(xtime.tv_sec); - rtc_update = xtime.tv_sec + 660; - } - write_sequnlock(&xtime_lock); } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/