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-rw-r--r--arch/x86_64/kernel/time.c41
1 files changed, 12 insertions, 29 deletions
diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 7f58fa682491..473b514b66e4 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -504,42 +504,25 @@ unsigned long long sched_clock(void)
504 504
505static unsigned long get_cmos_time(void) 505static unsigned long get_cmos_time(void)
506{ 506{
507 unsigned int timeout = 1000000, year, mon, day, hour, min, sec; 507 unsigned int year, mon, day, hour, min, sec;
508 unsigned char uip = 0, this = 0;
509 unsigned long flags; 508 unsigned long flags;
510 unsigned extyear = 0; 509 unsigned extyear = 0;
511 510
512/*
513 * The Linux interpretation of the CMOS clock register contents: When the
514 * Update-In-Progress (UIP) flag goes from 1 to 0, the RTC registers show the
515 * second which has precisely just started. Waiting for this can take up to 1
516 * second, we timeout approximately after 2.4 seconds on a machine with
517 * standard 8.3 MHz ISA bus.
518 */
519
520 spin_lock_irqsave(&rtc_lock, flags); 511 spin_lock_irqsave(&rtc_lock, flags);
521 512
522 while (timeout && (!uip || this)) { 513 do {
523 uip |= this; 514 sec = CMOS_READ(RTC_SECONDS);
524 this = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP; 515 min = CMOS_READ(RTC_MINUTES);
525 timeout--; 516 hour = CMOS_READ(RTC_HOURS);
526 } 517 day = CMOS_READ(RTC_DAY_OF_MONTH);
527 518 mon = CMOS_READ(RTC_MONTH);
528 /* 519 year = CMOS_READ(RTC_YEAR);
529 * Here we are safe to assume the registers won't change for a whole
530 * second, so we just go ahead and read them.
531 */
532 sec = CMOS_READ(RTC_SECONDS);
533 min = CMOS_READ(RTC_MINUTES);
534 hour = CMOS_READ(RTC_HOURS);
535 day = CMOS_READ(RTC_DAY_OF_MONTH);
536 mon = CMOS_READ(RTC_MONTH);
537 year = CMOS_READ(RTC_YEAR);
538
539#ifdef CONFIG_ACPI 520#ifdef CONFIG_ACPI
540 if (acpi_fadt.revision >= FADT2_REVISION_ID && acpi_fadt.century) 521 if (acpi_fadt.revision >= FADT2_REVISION_ID &&
541 extyear = CMOS_READ(acpi_fadt.century); 522 acpi_fadt.century)
523 extyear = CMOS_READ(acpi_fadt.century);
542#endif 524#endif
525 } while (sec != CMOS_READ(RTC_SECONDS));
543 526
544 spin_unlock_irqrestore(&rtc_lock, flags); 527 spin_unlock_irqrestore(&rtc_lock, flags);
545 528