Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit fbbf53f7 authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Alexandre Belloni
Browse files

rtc: pcf8523: refuse to write dates later than 2099 



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: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent c60faa3a

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;