Commit ede44c90 authored by Alexandre Belloni's avatar Alexandre Belloni
Browse files

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: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 2da424af

drivers/rtc/rtc-pcf8523.c

+3 −22
Original line number Diff line number Diff line
@@ -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;

	}

		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);

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