[PATCH] x86_64: Handle years beyond 2100

ACPIv2 has an official but optional way to get a date >2100.  Use it.
But all the platforms I tested didn't seem to support it.  But anyways
the x86-64 kernel should be ready for the 22nd century now.  Actually i
shouldn't care about this because I will be dead by then @)

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 86039ba..2f7c212 100644 (file)
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -517,6 +517,7 @@ static unsigned long get_cmos_time(void)
        unsigned int timeout = 1000000, year, mon, day, hour, min, sec;
        unsigned char uip = 0, this = 0;
        unsigned long flags;
+       unsigned extyear = 0;
 
 /*
  * The Linux interpretation of the CMOS clock register contents: When the
@@ -545,6 +546,11 @@ static unsigned long get_cmos_time(void)
        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);
+#endif
+
        spin_unlock_irqrestore(&rtc_lock, flags);
 
        /*
@@ -559,11 +565,17 @@ static unsigned long get_cmos_time(void)
        BCD_TO_BIN(mon);
        BCD_TO_BIN(year);
 
-       /*
-        * x86-64 systems only exists since 2002.
-        * This will work up to Dec 31, 2100
-        */
-       year += 2000;
+       if (extyear) {
+               BCD_TO_BIN(extyear);
+               year += extyear;
+               printk(KERN_INFO "Extended CMOS year: %d\n", extyear);
+       } else { 
+               /*
+                * x86-64 systems only exists since 2002.
+                * This will work up to Dec 31, 2100
+                */
+               year += 2000;
+       }
 
        return mktime(year, mon, day, hour, min, sec);
 }