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From 39869587dac09c9e738960ccdf01e1dc62a906f7 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Mon, 29 Oct 2018 14:45:45 +0000
Subject: [PATCH] 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>
---
drivers/rtc/rtc-pcf8523.c | 24 ++++++++++++++++++++++--
1 file changed, 22 insertions(+), 2 deletions(-)
--- a/drivers/rtc/rtc-pcf8523.c
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -242,8 +242,28 @@ static int pcf8523_rtc_read_time(struct
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, ®s[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);
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