alarmtimer: add rtc irq support for alarm

Add the rtc irq support for alarmtimer to wakeup the
alarm during system suspend.

Change-Id: I41b774ed4e788359321e1c6a564551cc9cd40c8e
Signed-off-by: Xiaocheng Li <lix@codeaurora.org>
alarmtimer: return EINVAL instead of ENOTSUPP if rtcdev doesn't exist

commit 98d6f4dd84a134d942827584a3c5f67ffd8ec35f upstream.

Fedora Ruby maintainer reported latest Ruby doesn't work on Fedora Rawhide
on ARM. (http://bugs.ruby-lang.org/issues/9008)

Because of, commit 1c6b39ad3f (alarmtimers: Return -ENOTSUPP if no
RTC device is present) intruduced to return ENOTSUPP when
clock_get{time,res} can't find a RTC device. However this is incorrect.

First, ENOTSUPP isn't exported to userland (ENOTSUP or EOPNOTSUP are the
closest userland equivlents).

Second, Posix and Linux man pages agree that clock_gettime and
clock_getres should return EINVAL if clk_id argument is invalid.
While the arugment that the clockid is valid, but just not supported
on this hardware could be made, this is just a technicality that
doesn't help userspace applicaitons, and only complicates error
handling.

Thus, this patch changes the code to use EINVAL.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Reported-by: Vit Ondruch <v.ondruch@tiscali.cz>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
[jstultz: Tweaks to commit message to include full rational]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
rtc: alarm: set power_on_alarm again when calling alarmtimer_resume

The power_on alarm might be replaced or cleared during alarm
suspend and resume process.So restore the power_on alarm into RTC
during alarm resume.

Change-Id: I1eefb082f9dfbd78517f3da1cc60a989853555fd
Signed-off-by: Mao Jinlong <c_jmao@codeaurora.org>
rtc: alarm: init power_on_alarm_lock mutex in alarmtimer_rtc_timer_init

Moved mutex_init of power_on_alarm_lock into alarmtimer_rtc_timer_init
so that if CONFIG_RTC_CLASS is not enabled, we dont try to initialize
the mutex.  This fixes a build issue when !CONFIG_RTC_CLASS

Change-Id: I270564b94fd54162aa177a2c9767655098662259
Signed-off-by: Kumar Gala <galak@codeaurora.org>
alarmtimer: add alarm_forward_now

Similar to hrtimer_forward_now, move the expires time forward to an
interval from the current time of the associated clock.

Change-Id: I73fed223321167507b6eddcb7a57d235ffcfc1be
Signed-off-by: Todd Poynor <toddpoynor@google.com>
alarmtimer: implement minimum alarm interval for allowing suspend

alarmtimer suspend return -EBUSY if the next alarm will fire in less
than 2 seconds.  This allows one RTC seconds tick to occur subsequent
to this check before the alarm wakeup time is set, ensuring the wakeup
time is still in the future (assuming the RTC does not tick one more
second prior to setting the alarm).  If suspend is rejected, hold a
wakeup source for 2 seconds to process the alarm prior to reattempting
suspend.

Change-Id: If38e2568da0ea01dfee6e00323ce7e2c00f2f110
Signed-off-by: Todd Poynor <toddpoynor@google.com>