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: Yauhen Kharuzhy <jekhor@gmail.com>
Cc: Daniel Mack <daniel@caiaq.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-mxc.c b/drivers/rtc/rtc-mxc.c
index 39e41fbdf08b..11b7b614fc8d 100644
--- a/drivers/rtc/rtc-mxc.c
+++ b/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);