x86: share rtc code

Remove the rtc code from time_64.c and add the extra bits to the
i386 path. The ACPI century check is probably valid for i386 as
well, but this is material for a separate patch.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 63 insertions, 33 deletions

diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index 45bf54d9f4c5..d040840ff1b6 100644
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -1,11 +1,32 @@
 /*
  * RTC related functions
  */
+#include <linux/acpi.h>
 #include <linux/bcd.h>
 #include <linux/mc146818rtc.h>
 
 #include <asm/time.h>
 
+#ifdef CONFIG_X86_32
+# define CMOS_YEARS_OFFS 1900
+/*
+ * This is a special lock that is owned by the CPU and holds the index
+ * register we are working with.  It is required for NMI access to the
+ * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
+ */
+volatile unsigned long cmos_lock = 0;
+EXPORT_SYMBOL(cmos_lock);
+#else
+/*
+ * x86-64 systems only exists since 2002.
+ * This will work up to Dec 31, 2100
+ */
+# define CMOS_YEARS_OFFS 2000
+#endif
+
+DEFINE_SPINLOCK(rtc_lock);
+EXPORT_SYMBOL(rtc_lock);
+
 /*
  * In order to set the CMOS clock precisely, set_rtc_mmss has to be
  * called 500 ms after the second nowtime has started, because when
@@ -22,10 +43,12 @@ int mach_set_rtc_mmss(unsigned long nowtime)
         int real_seconds, real_minutes, cmos_minutes;
         unsigned char save_control, save_freq_select;
 
-        save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
+         /* tell the clock it's being set */
+        save_control = CMOS_READ(RTC_CONTROL);
         CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
 
-        save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
+        /* stop and reset prescaler */
+        save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
         CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
 
         cmos_minutes = CMOS_READ(RTC_MINUTES);
@@ -40,8 +63,9 @@ int mach_set_rtc_mmss(unsigned long nowtime)
          */
         real_seconds = nowtime % 60;
         real_minutes = nowtime / 60;
+        /* correct for half hour time zone */
         if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
-                real_minutes += 30;             /* correct for half hour time zone */
+                real_minutes += 30;
         real_minutes %= 60;
 
         if (abs(real_minutes - cmos_minutes) < 30) {
@@ -73,18 +97,32 @@ int mach_set_rtc_mmss(unsigned long nowtime)
 
 unsigned long mach_get_cmos_time(void)
 {
-        unsigned int year, mon, day, hour, min, sec;
-
-        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);
-        } while (sec != CMOS_READ(RTC_SECONDS));
-
-        if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+        unsigned int year, mon, day, hour, min, sec, century = 0;
+
+        /*
+         * If UIP is clear, then we have >= 244 microseconds before
+         * RTC registers will be updated.  Spec sheet says that this
+         * is the reliable way to read RTC - registers. If UIP is set
+         * then the register access might be invalid.
+         */
+        while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
+                cpu_relax();
+
+        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);
+
+#if defined(CONFIG_ACPI) && defined(CONFIG_X86_64)
+        /* CHECKME: Is this really 64bit only ??? */
+        if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
+            acpi_gbl_FADT.century)
+                century = CMOS_READ(acpi_gbl_FADT.century);
+#endif
+
+        if (RTC_ALWAYS_BCD || !(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)) {
                 BCD_TO_BIN(sec);
                 BCD_TO_BIN(min);
                 BCD_TO_BIN(hour);
@@ -93,24 +131,19 @@ unsigned long mach_get_cmos_time(void)
                 BCD_TO_BIN(year);
         }
 
-        year += 1900;
-        if (year < 1970)
-                year += 100;
+        if (century) {
+                BCD_TO_BIN(century);
+                year += century * 100;
+                printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
+        } else {
+                year += CMOS_YEARS_OFFS;
+                if (year < 1970)
+                        year += 100;
+        }
 
         return mktime(year, mon, day, hour, min, sec);
 }
 
-DEFINE_SPINLOCK(rtc_lock);
-EXPORT_SYMBOL(rtc_lock);
-
-/*
- * This is a special lock that is owned by the CPU and holds the index
- * register we are working with.  It is required for NMI access to the
- * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
- */
-volatile unsigned long cmos_lock = 0;
-EXPORT_SYMBOL(cmos_lock);
-
 /* Routines for accessing the CMOS RAM/RTC. */
 unsigned char rtc_cmos_read(unsigned char addr)
 {
@@ -138,8 +171,6 @@ static int set_rtc_mmss(unsigned long nowtime)
         int retval;
         unsigned long flags;
 
-        /* gets recalled with irq locally disabled */
-        /* XXX - does irqsave resolve this? -johnstul */
         spin_lock_irqsave(&rtc_lock, flags);
         retval = set_wallclock(nowtime);
         spin_unlock_irqrestore(&rtc_lock, flags);
@@ -150,8 +181,7 @@ static int set_rtc_mmss(unsigned long nowtime)
 /* not static: needed by APM */
 unsigned long read_persistent_clock(void)
 {
-        unsigned long retval;
-        unsigned long flags;
+        unsigned long retval, flags;
 
         spin_lock_irqsave(&rtc_lock, flags);
         retval = get_wallclock();