X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Farm%2Fmach-footbridge%2Ftime.c;fp=arch%2Farm%2Fmach-footbridge%2Ftime.c;h=2c64a0b0502e6beaac9f19596854c55add0cae8a;hb=64ba3f394c830ec48a1c31b53dcae312c56f1604;hp=5d02e95dede310ac52c00cb3e8832b5a83760d09;hpb=be1e6109ac94a859551f8e1774eb9a8469fe055c;p=linux-2.6.git

diff --git a/arch/arm/mach-footbridge/time.c b/arch/arm/mach-footbridge/time.c
index 5d02e95de..2c64a0b05 100644
--- 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);