drivers/rtc/rtc-mxc.c: fix setting time for MX1 SoC

There is no way to track year in the i.MX1 RTC: Days Counter register is
9-bit wide only.  Attempt to save date after 1970-01-01 plus 512 days
causes endless loop in mxc_rtc_set_mmss().  Fix this by resetting year to
1970.

[akpm@linux-foundation.org: use conventional comment layout]
Signed-off-by: NYauhen Kharuzhy <jekhor@gmail.com>
Cc: Daniel Mack <daniel@caiaq.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-mxc.c

@@ -290,6 +290,17 @@ static int mxc_rtc_read_time(struct device *dev, struct rtc_time *tm)
  */
 static int mxc_rtc_set_mmss(struct device *dev, unsigned long time)
 {
+	/*
+	 * TTC_DAYR register is 9-bit in MX1 SoC, save time and day of year only
+	 */
+	if (cpu_is_mx1()) {
+		struct rtc_time tm;
+
+		rtc_time_to_tm(time, &tm);
+		tm.tm_year = 70;
+		rtc_tm_to_time(&tm, &time);
+	}
+
 	/* Avoid roll-over from reading the different registers */
 	do {
 		set_alarm_or_time(dev, MXC_RTC_TIME, time);