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authorMatt Mackall <mpm@selenic.com>2006-03-28 01:56:01 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-28 09:16:00 -0800
commit641f71f5f6ed251959ef8f88b1d0edc6ef7a4632 (patch)
tree8a493d60c361dc9f2e1f98805b276c96db2ad67c /arch
parent63732c2f37093d63102d53e70866cf87bf0c0479 (diff)
[PATCH] RTC: Remove RTC UIP synchronization on x86_64
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>
Diffstat (limited to 'arch')
-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 7f58fa68249..473b514b66e 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)
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);