rtc: pcf8523: refuse to write dates later than 2099 (fbbf53f7) · Commits · 戴 / test

When the chip increments the YEAR register and it already holds bin2bcd(99) it reads as 0 afterwards. With this behaviour the last valid day (without trickery) that has a representation is 2099-12-31 23:59:59. So refuse to write later dates. Signed-off-by:

Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by:

Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-pcf8523.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -219,6 +219,17 @@ static int pcf8523_rtc_set_time(struct device dev, struct rtc_time tm)
		u8 regs[8];
		int err;

		/*
		* The hardware can only store values between 0 and 99 in it's YEAR
		* register (with 99 overflowing to 0 on increment).
		* After 2100-02-28 we could start interpreting the year to be in the
		* interval [2100, 2199], but there is no path to switch in a smooth way
		* because the chip handles YEAR=0x00 (and the out-of-spec
		* YEAR=0xa0) as a leap year, but 2100 isn't.
		*/
		if (tm->tm_year < 100 \|\| tm->tm_year >= 200)
		return -EINVAL;

		err = pcf8523_stop_rtc(client);
		if (err < 0)
		return err;

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