Revert "rtc: pcf8523: properly handle oscillator stop bit"

This reverts commit ede44c908d44b166a5b6bd7caacd105c2ff5a70f.

See: https://github.com/raspberrypi/firmware/issues/1065

Signed-off-by: Phil Elwell <phil@raspberrypi.org>

diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
index 8b6fb20..ad2231f 100644 (file)
--- a/drivers/rtc/rtc-pcf8523.c
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -242,8 +242,28 @@ static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
        if (err < 0)
                return err;
 
-       if (regs[0] & PCF8523_SECONDS_OS)
-               return -EINVAL;
+       if (regs[0] & PCF8523_SECONDS_OS) {
+               /*
+                * If the oscillator was stopped, try to clear the flag. Upon
+                * power-up the flag is always set, but if we cannot clear it
+                * the oscillator isn't running properly for some reason. The
+                * sensible thing therefore is to return an error, signalling
+                * that the clock cannot be assumed to be correct.
+                */
+
+               regs[0] &= ~PCF8523_SECONDS_OS;
+
+               err = pcf8523_write(client, PCF8523_REG_SECONDS, regs[0]);
+               if (err < 0)
+                       return err;
+
+               err = pcf8523_read(client, PCF8523_REG_SECONDS, &regs[0]);
+               if (err < 0)
+                       return err;
+
+               if (regs[0] & PCF8523_SECONDS_OS)
+                       return -EAGAIN;
+       }
 
        tm->tm_sec = bcd2bin(regs[0] & 0x7f);
        tm->tm_min = bcd2bin(regs[1] & 0x7f);