Commit cce3ce89 authored by Huacai Chen's avatar Huacai Chen Committed by Linus Torvalds
Browse files

rtc: fix CMOS time error after writing /proc/acpi/alarm 



When writing /proc/acpi/alarm in adjust mode, e.g.
	echo "+0000-00-00 00:00:15" >/proc/acpi/alarm
The "century" field should be read and added to "year" field before
writing, otherwise the CMOS time will go back to 2000 years ago, e.g.
	# cat /proc/acpi/alarm
	0008-06-21 11:38:46
Then the system time may be reset to the date of manufacture after
rebooting. This patch fixed this issue.

Signed-off-by: default avatarHuacai Chen <huacai.chen@intel.com>
Acked-by: default avatarPavel Machek <pavel@suse.cz>
Acked-by: default avatarZhao Yakui <yakui.zhao@intel.com>
Acked-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Acked-by: default avatarLen Brown <lenb@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 471d47e3

drivers/acpi/sleep/proc.c

+4 −1
Original line number Diff line number Diff line
@@ -315,8 +315,11 @@ acpi_system_write_alarm(struct file *file, 
		cmos_bcd_write(day, acpi_gbl_FADT.day_alarm, rtc_control);

	if (acpi_gbl_FADT.month_alarm)

		cmos_bcd_write(mo, acpi_gbl_FADT.month_alarm, rtc_control);

	if (acpi_gbl_FADT.century)

	if (acpi_gbl_FADT.century) {

		if (adjust)

			yr += cmos_bcd_read(acpi_gbl_FADT.century, rtc_control) * 100;

		cmos_bcd_write(yr / 100, acpi_gbl_FADT.century, rtc_control);

	}

	/* enable the rtc alarm interrupt */

	rtc_control |= RTC_AIE;

	CMOS_WRITE(rtc_control, RTC_CONTROL);