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>
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2da424af45
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1 changed files with 3 additions and 22 deletions
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@ -178,28 +178,8 @@ static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
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if (err < 0)
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return err;
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if (regs[0] & REG_SECONDS_OS) {
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/*
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* If the oscillator was stopped, try to clear the flag. Upon
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* power-up the flag is always set, but if we cannot clear it
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* the oscillator isn't running properly for some reason. The
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* sensible thing therefore is to return an error, signalling
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* that the clock cannot be assumed to be correct.
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*/
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regs[0] &= ~REG_SECONDS_OS;
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err = pcf8523_write(client, REG_SECONDS, regs[0]);
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if (err < 0)
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return err;
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err = pcf8523_read(client, REG_SECONDS, ®s[0]);
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if (err < 0)
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return err;
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if (regs[0] & REG_SECONDS_OS)
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return -EAGAIN;
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}
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if (regs[0] & REG_SECONDS_OS)
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return -EINVAL;
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tm->tm_sec = bcd2bin(regs[0] & 0x7f);
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tm->tm_min = bcd2bin(regs[1] & 0x7f);
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@ -235,6 +215,7 @@ static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
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return err;
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regs[0] = REG_SECONDS;
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/* This will purposely overwrite REG_SECONDS_OS */
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regs[1] = bin2bcd(tm->tm_sec);
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regs[2] = bin2bcd(tm->tm_min);
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regs[3] = bin2bcd(tm->tm_hour);
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