Several architectures have a dummy timer driver tightly coupled with
their broadcast code to support machines without cpu-local timers (or
where there is a lack of driver support).

Since 12ad1000: "clockevents: Add generic timer broadcast function"
it's been possible to write broadcast-capable timer drivers decoupled
from the broadcast mechanism. We can use this functionality to implement
a generic dummy timer driver that can be shared by all architectures
with generic tick broadcast (ARCH_HAS_TICK_BROADCAST).

This patch implements a generic dummy timer using this facility.

[sboyd: Make percpu data static, use __this_cpu_ptr(), move to
        early_initcall to properly register on each CPU, only
	register if more than one CPU possible]
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>,
Cc: John Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1370291642-13259-3-git-send-email-sboyd@codeaurora.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

On an SMP system with only one global clockevent and a dummy
clockevent per CPU we run into problems. We want the dummy
clockevents to be registered as the per CPU tick devices, but
we can only achieve that if we register the dummy clockevents
before the global clockevent or if we artificially inflate the
rating of the dummy clockevents to be higher than the rating
of the global clockevent. Failure to do so leads to boot
hangs when the dummy timers are registered on all other CPUs
besides the CPU that accepted the global clockevent as its tick
device and there is no broadcast timer to poke the dummy
devices.

If we're registering multiple clockevents and one clockevent is
global and the other is local to a particular CPU we should
choose to use the local clockevent regardless of the rating of
the device. This way, if the clockevent is a dummy it will take
the tick device duty as long as there isn't a higher rated tick
device and any global clockevent will be bumped out into
broadcast mode, fixing the problem described above.
Reported-and-tested-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Tested-by: soren.brinkmann@xilinx.com
Cc: John Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20130613183950.GA32061@codeaurora.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Some new users of the ARM sched_clock framework are going through
the arm-soc tree. Before 38ff87f7 (sched_clock: Make ARM's
sched_clock generic for all architectures, 2013-06-01) the header
file was in asm, but now it's in linux. One solution would be to
do an evil merge of the arm-soc tree and fix up the asm users,
but it's easier to add a temporary asm header that we can remove
along with the few stragglers after the merge window is over.
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

This reverts commit 55a68c23.

In order to avoid a collision with dw_apb_timer changes in
the arm-soc tree, revert this change.

I'm leaving it to the arm-soc folks to sort out if they want
to keep the other side of the collision or if they're just going
to back it all out and try again during the next release cycle.
Reported-by: NDinh Nguyen <dinguyen@altera.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

There is a small race between when the cycle count is read from
the hardware and when the epoch stabilizes. Consider this
scenario:

 CPU0                           CPU1
 ----                           ----
 cyc = read_sched_clock()
 cyc_to_sched_clock()
                                 update_sched_clock()
                                  ...
                                  cd.epoch_cyc = cyc;
  epoch_cyc = cd.epoch_cyc;
  ...
  epoch_ns + cyc_to_ns((cyc - epoch_cyc)

The cyc on cpu0 was read before the epoch changed. But we
calculate the nanoseconds based on the new epoch by subtracting
the new epoch from the old cycle count. Since epoch is most likely
larger than the old cycle count we calculate a large number that
will be converted to nanoseconds and added to epoch_ns, causing
time to jump forward too much.

Fix this problem by reading the hardware after the epoch has
stabilized.

Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Nothing about the sched_clock implementation in the ARM port is
specific to the architecture. Generalize the code so that other
architectures can use it by selecting GENERIC_SCHED_CLOCK.
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
[jstultz: Merge minor collisions with other patches in my tree]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

If we're suspended and sched_clock() is called we're going to
read the hardware one more time and throw away that value and
return back the cached value we saved during the suspend
callback. This is wasteful. Let's short circuit all that and
return the cached value as early as possible if we're suspended.
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The needs_suspend member is unused now that we always do the
suspend/resume handling (see 6a4dae5e (ARM: 7565/1: sched: stop
sched_clock() during suspend, 2012-10-23)).
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Export symbols so they can be used by
drivers/staging/android/alarm-dev.c if it is built as a module.
So far alarm-dev is built-in but module support is planned (see
drivers/staging/android/TODO).
Signed-off-by: NMarcus Gelderie <redmnic@gmail.com>
[jstultz: tweaked commit message, also export newly added functions]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Merge branch 'timers/clockevents' of git://git.linaro.org/people/dlezcano/clockevents into timers/core

This patch adds a clocksource/clockevent driver for the timer found on some
models in the TI-Nspire calculator series. The timer has two 16bit subtimers
within its memory mapped I/O interface but only the first can generate
interrupts. The first subtimer is used to generate clockevents but only if an
interrupt number and register is given.

The interrupt acknowledgement mechanism is a little strange because the
interrupt mask and acknowledge registers are located in another memory mapped
I/O peripheral. The address of this register is passed to the driver through
device tree bindings.

The second subtimer is used as a clocksource because it isn't capable of
generating an interrupt. This subtimer is always added.
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NDaniel Tang <dt.tangr@gmail.com>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

Add Freescale Vybrid Family period interrupt timer support.
Signed-off-by: NJingchang Lu <b35083@freescale.com>
Reviewed-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

irq_of_parse_and_map() returns 0 on error, while the code checks for NO_IRQ.
This breaks on platforms that have NO_IRQ != 0.

Cc: <stable@vger.kernel.org>
Signed-off-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

The patch "x86: Increase precision of x86_platform.get/set_wallclock"
changed the x86 platform set_wallclock/get_wallclock interfaces to
use nsec granular timespecs instead of a second granular interface.

However, that patch missed converting the vrtc code, so this patch
converts those functions to use timespecs.

Many thanks to the kbuild test robot for finding this!
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Below is a patch from android kernel that maintains a histogram of
suspend times. Please review and provide feedback.

Statistices on the time spent in suspend are kept in
/sys/kernel/debug/sleep_time.

Cc: Android Kernel Team <kernel-team@android.com>
Cc: Colin Cross <ccross@android.com>
Cc: Todd Poynor <toddpoynor@google.com>
Cc: San Mehat <san@google.com>
Cc: Benoit Goby <benoit@android.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NColin Cross <ccross@android.com>
Signed-off-by: NTodd Poynor <toddpoynor@google.com>
[zoran.markovic@linaro.org: Re-formatted suspend time table to better
fit expected values. Moved accounting of suspend time into timekeeping
core. Removed CONFIG_SUSPEND_TIME flag and made the feature conditional
on CONFIG_DEBUG_FS. Changed the file name to sleep_time to better fit
terminology in timekeeping core. Changed seq_printf to seq_puts. Tweaked
commit message]
Signed-off-by: NZoran Markovic <zoran.markovic@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Add support for clocks CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM,
thereby enabling wakeup alarm timers via file descriptors.
Signed-off-by: NTodd Poynor <toddpoynor@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Add functions needed for hooking up alarmtimer to timerfd:

* alarm_restart: Similar to hrtimer_restart, restart an alarmtimer after
  the expires time has already been updated (as with alarm_forward).

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

* alarm_start_relative: Start an alarmtimer with an expires time relative to
  the current time of the associated clock.

* alarm_expires_remaining: Similar to hrtimer_expires_remaining, return the
  amount of time remaining until alarm expiry.
Signed-off-by: NTodd Poynor <toddpoynor@google.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

All the virtualized platforms (KVM, lguest and Xen) have persistent
wallclocks that have more than one second of precision.

read_persistent_wallclock() and update_persistent_wallclock() allow
for nanosecond precision but their implementation on x86 with
x86_platform.get/set_wallclock() only allows for one second precision.
This means guests may see a wallclock time that is off by up to 1
second.

Make set_wallclock() and get_wallclock() take a struct timespec
parameter (which allows for nanosecond precision) so KVM and Xen
guests may start with a more accurate wallclock time and a Xen dom0
can maintain a more accurate wallclock for guests.
Signed-off-by: NDavid Vrabel <david.vrabel@citrix.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The time.h header seems not to be used by current code.
Removing this include allows the driver to build on other
architecture that do not have this header.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jamie Iles <jamie@jamieiles.com>
Cc: Dinh Nguyen <dinguyen@altera.com>
Acked-by: NJamie Iles <jamie@jamieiles.com>
Signed-off-by: NBaruch Siach <baruch@tkos.co.il>
[tweaked commit message and header]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

It seems we made a mistake when creating dw_apb_timer_of.c:
picoxcell sched_clock had parts that were not related to
dw_apb_timer, yet we moved them to dw_apb_timer_of, and tried to
use them on socfpga.

This results in system where user/system time is not measured
properly, as demonstrated by

    time dd if=/dev/urandom of=/dev/zero bs=100000 count=100

So this patch switches sched_clock to hardware that exists on both
platforms, and adds missing of_node_put() in dw_apb_timer_init().
Signed-off-by: NPavel Machek <pavel@denx.de>
Acked-by: NJamie Iles <jamie@jamieiles.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The function is currently mainly used in the networking code and
if others start using it, they must check the result, otherwise
it cannot be determined if the timespec conversion suceeded.
Currently no user lacks this check, but make future users aware of
a possible misusage.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

We've got the macro NSEC_PER_USEC defined in header file
include/linux/time.h. To make the code decent, this patch
replaces the immediate number 1000 to convert bewteen a
time value in microseconds and one in nanoseconds with the
macro NSEC_PER_USEC.
Signed-off-by: NLiu Ying <Ying.Liu@freescale.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

commit 7eaeb343 (clocksource: Provide unbind interface in sysfs)
implemented clocksource_select_fallback() which is not defined for
CONFIG_ARCH_USES_GETTIMEOFFSET=y. Add an empty inline function for
that.
Reported-by: NIngo Molnar <mingo@kernel.org>
Reported-by: fengguang.wu@intel.com
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Unbreak architectures which do not use clockevents, but require to
build some of the core timekeeping infrastructure
Reported-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Provide a sysfs interface to allow unbinding of clockevent
devices. The device is unbound if it is unused or if there is a
replacement device available. Unbinding of broadcast devices is not
supported as we don't want to foster that nonsense. If no replacement
device is available the unbind returns -EBUSY. Unbind is available
from the kernel and through sysfs, which is necessary to drop the
module refcount.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.499216659@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Split out the clockevent device selection logic. Preparatory patch to
allow unbinding active clockevent devices.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.431796247@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Provide a simple sysfs interface for the clockevent devices. Show the
current active clockevent device.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.371634778@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

We want to be able to remove clockevent modules as well. Add a
refcount so we don't remove a module with an active clock event
device.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.307435149@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

No need to call another function and have duplicated cases.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.235746557@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Now that the notifier chain is gone there are no other users and it's
pointless to nest tick_device_lock inside of clockevents_lock because
there is no other use case.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.162888472@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

7+ years and still a single user. Kill it.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.098520211@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

The unregister call can fail, if the clocksource is the current one
and there is no replacement clocksource available. It can also fail,
if the clocksource is the watchdog clocksource and I'm not going to
provide support for this.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143436.029915527@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

With the module refcount held for the current clocksource there is no
way to unload the module. 

Provide a sysfs interface which allows to unbind the clocksource. One
could argue that the clocksource override could be (ab)used to do so,
but the clocksource override cannot be used from the kernel itself,
while an unbind function can be used to programmatically check whether
a clocksource can be shutdown or not.

The unbind functionality uses the new skip current feature of
clocksource_select and verifies that a fallback clocksource has been
installed. If the clocksource which should be unbound is the current
clocksource and no fallback can be found, unbind returns -EBUSY.

This does not support the unbinding of a clocksource which is used as
the watchdog clocksource. No point in fostering crappy hardware.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.964218245@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Split out the user string input for clocksource override. Preparatory
patch for unbind.

[ jstultz: Fix an off by one error ]
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.895851338@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Preparatory patch for clocksource unbind support.

Split out code from clocksource_select and modify it, so it skips the
current clocksource on request and tries to find a fallback
clocksource. Convert all existing users. No functional change.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.834965397@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Add a module refcount, so the current clocksource cannot be removed
unconditionally.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.762417789@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

timekeeping_notify() can fail due cs->enable() failure. Though the
caller does not notice and happily keeps the wrong clocksource as the
current one.

Let the caller know about failure, so the current clocksource will be
shown correctly in sysfs.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.696321912@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

If a clocksource has a (wrong) high rating, but can't be used as a
timebase for oneshot tick mode, it is unconditionally selected even
when the system is already in oneshot tick mode. This causes full
system failure.

Verify the clocksource selection against the oneshot mode.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Link: http://lkml.kernel.org/r/20130425143435.635040849@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Acked-by: NJamie Iles <jamie@jamieiles.com>
Link: http://lkml.kernel.org/r/20130425143435.558006195@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>