[linux-pm] Power Mangement Interfaces

[David Brownell]

On Friday 30 March 2007 5:21 pm, Johannes Berg wrote:

> Hm, another thing. The RTC alarm wakeup event, wouldn't that require
> programming the time too? And if so, should that be done through the
> power interface to it?

There's already a cross-platform interface to RTC wakeup alarms; no
new interface is needed (or desirable), much less one that requires
any new or modified /sys/power/... files.

 - Enable the wakeup event in /sys/devices/.../power/wakeup
   (alternate names include /sys/class/rtc/.../device/power/wakeup)

 - Userspace can set the alarm using

    * /dev/rtcX and one ioctl:  RTC_WKALM_SET
    * /dev/rtcX and two ioctls:  RTC_ALM_SET, then RTC_AIE_ON
    * /sys/class/rtc/.../wakealarm

That works on multiple systems already.  I've just posted updates
to make it work for "rtc-cmos" on the RTC list.

- Dave