[peterson]

Here is an updated and probably final version.

It uses lipc-wait-event to not have to busy-wait, so there is virtually no additional overhead now. Precision is plus/minus a second at best, though the RTC clock may wake up several seconds earlier/later. But this should be okay.

N.B.: My wifi issue is only at work, so this must be a network problem (probably need a higher timeout). At home it is working flawlessly.

RTC=0

currentTime () {
        date +%s
}
 
wait_for () {
        # calculate the time we should return
        ENDWAIT=$(( $(currentTime) + $1 )) 

        # disable/reset current alarm
        echo 0 > /sys/class/rtc/rtc$RTC/wakealarm

        # set new alarm
        echo $ENDWAIT > /sys/class/rtc/rtc$RTC/wakealarm

        # check whether we could set the alarm successfully
        if [ $ENDWAIT -eq `cat /sys/class/rtc/rtc$RTC/wakealarm` ]; then
                # wait for timeout to expire
                while [ $(currentTime) -lt $ENDWAIT ]; do
                        REMAININGWAITTIME=$(( $ENDWAIT - $(currentTime) ))
                        if [ 0 -lt $REMAININGWAITTIME ]; then
                                # wait for device to resume from sleep, or for time out
                                lipc-wait-event -s $REMAININGWAITTIME com.lab126.powerd resuming || true
                        fi
                done
        else
                echo "Failure setting alarm on rtc$RTC, wanted $ENDWAIT, got `cat /sys/class/rtc/rtc$RTC/wakealarm`"
        fi   

        # not sure whether this is required
        lipc-set-prop com.lab126.powerd -i deferSuspend 1
}

# wait 2 hours and then wake up
wait_for 120 
echo "Good morning"