linux 2.6.16.38 w/ vs2.0.3-rc1

[linux-2.6.git] / arch / arm / mach-footbridge / time.c

diff --git a/arch/arm/mach-footbridge/time.c b/arch/arm/mach-footbridge/time.c
index 5d02e95..2c64a0b 100644 (file)
--- a/arch/arm/mach-footbridge/time.c
+++ b/arch/arm/mach-footbridge/time.c
@@ -34,12 +34,27 @@ static int rtc_base;
 static unsigned long __init get_isa_cmos_time(void)
 {
        unsigned int year, mon, day, hour, min, sec;
+       int i;
 
        // check to see if the RTC makes sense.....
        if ((CMOS_READ(RTC_VALID) & RTC_VRT) == 0)
                return mktime(1970, 1, 1, 0, 0, 0);
 
-       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);