From: David Brownell Date: Mon, 12 Feb 2007 08:52:47 +0000 (-0800) Subject: [PATCH] RTC gets sysfs wakealarm attribute X-Git-Tag: v2.6.21-rc1~274^2~159 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3925a5ce44330767f7f0de5c58c6a797009f0f75;p=pandora-kernel.git [PATCH] RTC gets sysfs wakealarm attribute This adds a new "wakealarm" sysfs attribute to RTC class devices which support alarm operations and are wakeup-capable: - It reads as either empty, or the scheduled alarm time as seconds since the POSIX epoch. (That time may already have passed, since nothing currently enforces one-shot alarm semantics.) - It can be written with an alarm time in the future, again seconds since the POSIX epoch, which enables the alarm. - It can be written with an alarm time not in the future (such as 0, the start of the POSIX epoch) to disable the alarm. Usage examples (some need GNU date) after "cd /sys/class/rtc/rtcN": alarm after 10 minutes: # echo $(( $(cat since_epoch) + 10 * 60 )) > wakealarm alarm tuesday evening 10pm: # date -d '10pm tuesday' "+%s" > wakealarm disable alarm: # echo 0 > wakealarm This resembles the /proc/acpi/alarm file in that nothing happens when the alarm triggers ... except possibly waking the system from sleep. It's also like that in a nasty way: not much can be done to prevent one task from clobbering another task's alarm settings. It differs from that file in that there's no in-kernel date parser. Note that a few RTCs ignore rtc_wkalrm.enabled when setting alarms, or aren't set up correctly, so they won't yet behave with this attribute. Signed-off-by: David Brownell Acked-by: Pavel Machek Cc: Alessandro Zummo Cc: Greg KH Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed