drivers/rtc/rtc-r9701.c: reset registers if invalid values are detected

hwclock refuses to set date/time if RTC registers contain invalid
values.  Check the date/time register values at probe time and
initialize them to make hwclock happy.

Signed-off-by: Andreas Dumberger <andreas.dumberger@tqs.de>
Signed-off-by: Anatolij Gustschin <agust@denx.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>

diff --git a/drivers/rtc/rtc-r9701.c b/drivers/rtc/rtc-r9701.c
index 7f8e6c2..33b6ba0 100644 (file)
--- a/drivers/rtc/rtc-r9701.c
+++ b/drivers/rtc/rtc-r9701.c
@@ -122,6 +122,7 @@ static const struct rtc_class_ops r9701_rtc_ops = {
 static int __devinit r9701_probe(struct spi_device *spi)
 {
        struct rtc_device *rtc;
+       struct rtc_time dt;
        unsigned char tmp;
        int res;
 
@@ -132,6 +133,27 @@ static int __devinit r9701_probe(struct spi_device *spi)
                return -ENODEV;
        }
 
+       /*
+        * The device seems to be present. Now check if the registers
+        * contain invalid values. If so, try to write a default date:
+        * 2000/1/1 00:00:00
+        */
+       r9701_get_datetime(&spi->dev, &dt);
+       if (rtc_valid_tm(&dt)) {
+               dev_info(&spi->dev, "trying to repair invalid date/time\n");
+               dt.tm_sec  = 0;
+               dt.tm_min  = 0;
+               dt.tm_hour = 0;
+               dt.tm_mday = 1;
+               dt.tm_mon  = 0;
+               dt.tm_year = 100;
+
+               if (r9701_set_datetime(&spi->dev, &dt)) {
+                       dev_err(&spi->dev, "cannot repair RTC register\n");
+                       return -ENODEV;
+               }
+       }
+
        rtc = rtc_device_register("r9701",
                                &spi->dev, &r9701_rtc_ops, THIS_MODULE);
        if (IS_ERR(rtc))