On Sunday 07 January 2007 22:44, David Brownell wrote: > On Sunday 07 January 2007 3:19 am, Pavel Machek wrote: > > > > > Create /sys/power/alarm. > > > The way it works is exactly the same as /proc/acpi/alarm. > > > I.e. "#echo yyyy-mm-dd hh-mm-ss >/sys/power/alarm" supports existing absolute time. > > > And "#echo +yyyy-mm-dd hh-mm-ss >/sys/power/alarm" supports a duration. > > > > NAK. /proc/acpi/alarm is a mess, and this just moves it to /sysfs. > > 'One value per file', please. > > Sort of like the appended patch, instead ... which doesn't need to know a > thing about ACPI. This is what I suggested in response to an earlier patch > from Paul Sokolovsky. > > - Dave > > > ================ CUT HERE > 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, after "cd /sys/class/rtc/rtcN": > > alarm after 45 minutes: > # echo $(( $(cat since_epoch) + 45 * 60 )) > wakealarm > alarm next tuesday evening (using GNU date): > # 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 <dbrownell at users.sourceforge.net> How do I ask to wake up "as soon as possible"? This is what a box that is testing suspend-resume would want to do. thanks, -Len
