linux 2.6.16.38 w/ vs2.0.3-rc1

[linux-2.6.git] / include / asm-i386 / mach-default / mach_time.h

diff --git a/include/asm-i386/mach-default/mach_time.h b/include/asm-i386/mach-default/mach_time.h
index 31eb5de..b749aa4 100644 (file)
--- a/include/asm-i386/mach-default/mach_time.h
+++ b/include/asm-i386/mach-default/mach_time.h
@@ -82,8 +82,21 @@ static inline int mach_set_rtc_mmss(unsigned long nowtime)
 static inline unsigned long mach_get_cmos_time(void)
 {
        unsigned int year, mon, day, hour, min, sec;
+       int i;
 
-       do {
+       /* 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.
+        * Let's hope other operating systems interpret the RTC the same way.
+        */
+       /* read RTC exactly on falling edge of update flag */
+       for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */
+               if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
+                       break;
+       for (i = 0 ; i < 1000000 ; i++) /* must try at least 2.228 ms */
+               if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
+                       break;
+       do { /* Isn't this overkill ? UIP above should guarantee consistency */
                sec = CMOS_READ(RTC_SECONDS);
                min = CMOS_READ(RTC_MINUTES);
                hour = CMOS_READ(RTC_HOURS);
@@ -91,18 +104,16 @@ static inline unsigned long mach_get_cmos_time(void)
                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) {
-               BCD_TO_BIN(sec);
-               BCD_TO_BIN(min);
-               BCD_TO_BIN(hour);
-               BCD_TO_BIN(day);
-               BCD_TO_BIN(mon);
-               BCD_TO_BIN(year);
-       }
-
-       year += 1900;
-       if (year < 1970)
+       if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+         {
+           BCD_TO_BIN(sec);
+           BCD_TO_BIN(min);
+           BCD_TO_BIN(hour);
+           BCD_TO_BIN(day);
+           BCD_TO_BIN(mon);
+           BCD_TO_BIN(year);
+         }
+       if ((year += 1900) < 1970)
                year += 100;
 
        return mktime(year, mon, day, hour, min, sec);