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[PATCH] RTC: Remove RTC UIP synchronization on x86_64

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Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Andi Kleen <ak@muc.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Matt Mackall 2006-03-28 01:56:01 -08:00 committed by Linus Torvalds
parent 63732c2f37
commit 641f71f5f6
1 changed files with 12 additions and 29 deletions
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41
arch/x86_64/kernel/time.c
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@ -504,42 +504,25 @@ unsigned long long sched_clock(void)
static unsigned long get_cmos_time(void)
{
unsigned int timeout = 1000000, year, mon, day, hour, min, sec;
unsigned char uip = 0, this = 0;
unsigned int year, mon, day, hour, min, sec;
unsigned long flags;
unsigned extyear = 0;
/*
* The Linux interpretation of the CMOS clock register contents: When the
* Update-In-Progress (UIP) flag goes from 1 to 0, the RTC registers show the
* second which has precisely just started. Waiting for this can take up to 1
* second, we timeout approximately after 2.4 seconds on a machine with
* standard 8.3 MHz ISA bus.
*/
spin_lock_irqsave(&rtc_lock, flags);
while (timeout && (!uip || this)) {
uip |= this;
this = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP;
timeout--;
}
/*
* Here we are safe to assume the registers won't change for a whole
* second, so we just go ahead and read them.
*/
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
hour = CMOS_READ(RTC_HOURS);
day = CMOS_READ(RTC_DAY_OF_MONTH);
mon = CMOS_READ(RTC_MONTH);
year = CMOS_READ(RTC_YEAR);
do {
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
hour = CMOS_READ(RTC_HOURS);
day = CMOS_READ(RTC_DAY_OF_MONTH);
mon = CMOS_READ(RTC_MONTH);
year = CMOS_READ(RTC_YEAR);
#ifdef CONFIG_ACPI
if (acpi_fadt.revision >= FADT2_REVISION_ID && acpi_fadt.century)
extyear = CMOS_READ(acpi_fadt.century);
if (acpi_fadt.revision >= FADT2_REVISION_ID &&
acpi_fadt.century)
extyear = CMOS_READ(acpi_fadt.century);
#endif
} while (sec != CMOS_READ(RTC_SECONDS));
spin_unlock_irqrestore(&rtc_lock, flags);