Currently the Xen wallclock is only updated every 11 minutes if NTP is
synchronized to its clock source (using the sync_cmos_clock() work).
If a guest is started before NTP is synchronized it may see an
incorrect wallclock time.

Use the pvclock_gtod notifier chain to receive a notification when the
system time has changed and update the wallclock to match.

This chain is called on every timer tick and we want to avoid an extra
(expensive) hypercall on every tick.  Because dom0 has historically
never provided a very accurate wallclock and guests do not expect one,
we can do this simply: the wallclock is only updated if the clock was
set.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-5-git-send-email-david.vrabel@citrix.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

If the clock was set (stepped), set the action parameter to functions
in the pvclock gtod notifier chain to non-zero.  This allows the
callee to only do work if the clock was stepped.

This will be used on Xen as the synchronization of the Xen wallclock
to the control domain's (dom0) system time will be done with this
notifier and updating on every timer tick is unnecessary and too
expensive.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-4-git-send-email-david.vrabel@citrix.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Instead of passing multiple bools to timekeeping_updated(), define
flags and use a single 'action' parameter.  It is then more obvious
what each timekeeping_update() call does.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-3-git-send-email-david.vrabel@citrix.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

commit 359cdd3f

(xen: maintain clock offset over save/restore) added
a clock_was_set() call into the xen resume code to propagate the
system time changes. With the modified hrtimer resume code, which
makes sure that all cpus are notified this call is not longer necessary.

[ tglx: Separated it from the hrtimer change ]

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk  <konrad.wilk@oracle.com>
Cc: John Stultz  <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-2-git-send-email-david.vrabel@citrix.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

hrtimers_resume() only reprograms the timers for the current CPU as it
assumes that all other CPUs are offline at this point in the resume
process. If other CPUs are online then their timers will not be
corrected and they may fire at the wrong time.

When running as a Xen guest, this assumption is not true.  Non-boot
CPUs are only stopped with IRQs disabled instead of offlining them.
This is a performance optimization as disabling the CPUs would add an
unacceptable amount of additional downtime during a live migration (>
200 ms for a 4 VCPU guest).

hrtimers_resume() cannot call on_each_cpu(retrigger_next_event,...)
as the other CPUs will be stopped with IRQs disabled.  Instead, defer
the call to the next softirq.

[ tglx: Separated the xen change out ]

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: Konrad Rzeszutek Wilk  <konrad.wilk@oracle.com>
Cc: John Stultz  <john.stultz@linaro.org>
Cc: <xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/1372329348-20841-2-git-send-email-david.vrabel@citrix.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Direct compare of jiffies related values does not work in the wrap
around case. Replace it with time_is_after_jiffies().

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/519BC066.5080600@acm.org


Cc: stable@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Commit 38ff87f7

 (sched_clock: Make ARM's sched_clock generic for all
architectures) changed the header to <linux/sched_clock.h>, so adapt
it in order to fix the following build error:

drivers/clocksource/vf_pit_timer.c:15:29: fatal error: asm/sched_clock.h: No such file or directory

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Cc: shawn.guo@linaro.org
Cc: sboyd@codeaurora.org
Cc: john.stultz@linaro.org
Link: http://lkml.kernel.org/r/1372116008-2323-1-git-send-email-festevam@gmail.com


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

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: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com&gt;,>
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.org


Signed-off-by: Thomas 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: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Stephen 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.org


Signed-off-by: Thomas 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: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John 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: Dinh Nguyen <dinguyen@altera.com>
Signed-off-by: John 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: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John 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: Stephen Boyd <sboyd@codeaurora.org>
[jstultz: Merge minor collisions with other patches in my tree]
Signed-off-by: John 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: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John 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: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: John 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: Marcus Gelderie <redmnic@gmail.com>
[jstultz: tweaked commit message, also export newly added functions]
Signed-off-by: John 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: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Daniel Tang <dt.tangr@gmail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Add Freescale Vybrid Family period interrupt timer support.

Signed-off-by: Jingchang Lu <b35083@freescale.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Daniel 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: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Daniel 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: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: John 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: Colin Cross <ccross@android.com>
Signed-off-by: Todd 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: Zoran Markovic <zoran.markovic@linaro.org>
Signed-off-by: John 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: Todd Poynor <toddpoynor@google.com>
Signed-off-by: John 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: Todd Poynor <toddpoynor@google.com>
Signed-off-by: John 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: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: John 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: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
[tweaked commit message and header]
Signed-off-by: John 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: Pavel Machek <pavel@denx.de>
Acked-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: John 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: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: John 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: Liu 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: John 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: Ingo Molnar <mingo@kernel.org>
Reported-by:  <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Unbreak architectures which do not use clockevents, but require to
build some of the core timekeeping infrastructure

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas 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: Thomas 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.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Split out the clockevent device selection logic. Preparatory patch to
allow unbinding active clockevent devices.

Signed-off-by: Thomas 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.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Provide a simple sysfs interface for the clockevent devices. Show the
current active clockevent device.

Signed-off-by: Thomas 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.de


Signed-off-by: Thomas 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: Thomas 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.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

No need to call another function and have duplicated cases.

Signed-off-by: Thomas 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.de


Signed-off-by: Thomas 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: Thomas 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.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

7+ years and still a single user. Kill it.

Signed-off-by: Thomas 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.de


Signed-off-by: Thomas 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: Thomas 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.de


Signed-off-by: Thomas Gleixner <tglx@linutronix.de>