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authorAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-03-03 09:55:47 +0100
committerAlexandre Belloni <alexandre.belloni@free-electrons.com>2016-03-14 17:08:30 +0100
commitede44c908d44b166a5b6bd7caacd105c2ff5a70f (patch)
treec3917e54ee7928b6bda3d84578f1a9cfb3c68a86
parent2da424af4531c4469408136772d6d5e0f8df748b (diff)
rtc: pcf8523: properly handle oscillator stop bit
The time and date register of the pcf8223 are undefined after a power reset. Properly handle the OS bit and return -EINVAL when that bit is set. It is properly removed when setting the time. This solves an issue where the time and date may be valid for rtc_valid_tm() but is not the current time. Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
-rw-r--r--drivers/rtc/rtc-pcf8523.c25
1 files changed, 3 insertions, 22 deletions
diff --git a/drivers/rtc/rtc-pcf8523.c b/drivers/rtc/rtc-pcf8523.c
index 988566c..28c48b3 100644
--- a/drivers/rtc/rtc-pcf8523.c
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -178,28 +178,8 @@ static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
if (err < 0)
return err;
- if (regs[0] & REG_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] &= ~REG_SECONDS_OS;
-
- err = pcf8523_write(client, REG_SECONDS, regs[0]);
- if (err < 0)
- return err;
-
- err = pcf8523_read(client, REG_SECONDS, &regs[0]);
- if (err < 0)
- return err;
-
- if (regs[0] & REG_SECONDS_OS)
- return -EAGAIN;
- }
+ if (regs[0] & REG_SECONDS_OS)
+ return -EINVAL;
tm->tm_sec = bcd2bin(regs[0] & 0x7f);
tm->tm_min = bcd2bin(regs[1] & 0x7f);
@@ -235,6 +215,7 @@ static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
return err;
regs[0] = REG_SECONDS;
+ /* This will purposely overwrite REG_SECONDS_OS */
regs[1] = bin2bcd(tm->tm_sec);
regs[2] = bin2bcd(tm->tm_min);
regs[3] = bin2bcd(tm->tm_hour);