Currently we keep sched_clock_tick() active for stable TSC in order to
keep the per-CPU state semi up-to-date. The (obvious) problem is that
by the time we detect TSC is borked, our per-CPU state is also borked.

So hook into the clocksource watchdog and call a method after we've
found it to still be stable.

There's the obvious race where the TSC goes wonky between finding it
stable and us running the callback, but closing that is too much work
and not really worth it, since we're already detecting TSC wobbles
after the fact, so we cannot, per definition, fully avoid funny clock
values.

And since the watchdog runs less often than the tick, this is also an
optimization.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Besides reusing existing code this removes the special case handling
for 64-bit masks, which causes clang to raise a shift count overflow
warning due to https://bugs.llvm.org//show_bug.cgi?id=10030.
Suggested-by: NDmitry Torokhov <dtor@chromium.org>
Signed-off-by: NMatthias Kaehlcke <mka@chromium.org>
Cc: Grant Grundler <grundler@chromium.org>
Cc: Greg Hackmann <ghackmann@google.com>
Cc: Michael Davidson <md@google.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/20170418233037.70990-1-mka@chromium.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

PeterZ reported that we'd fail to mark the TSC unstable when the
clocksource watchdog finds it unsuitable.

Allow a clocksource to run a custom action when its being marked
unstable and hook up the TSC unstable code.
Reported-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

There is no point in having an extra type for extra confusion. u64 is
unambiguous.

Conversion was done with the following coccinelle script:

@rem@
@@
-typedef u64 cycle_t;

@fix@
typedef cycle_t;
@@
-cycle_t
+u64
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>

The "cycles" argument should not be an absolute clocksource cycle
value, as the implementation's arithmetic will overflow relatively
easily with wide (64 bit) clocksource counters.

For performance, the implementation is simple and fast, since the
function is intended for only relatively small delta values of
clocksource cycles.

[jstultz: Fixed up to merge against HEAD & commit message tweaks,
 also included rewording suggestion by Ingo]
Signed-off-by: NChris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1480372524-15181-4-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

All the clocksource drivers's init function are now converted to return
an error code. CLOCKSOURCE_OF_DECLARE is no longer used as well as the
clksrc-of table.

Let's convert back the names:
 - CLOCKSOURCE_OF_DECLARE_RET => CLOCKSOURCE_OF_DECLARE
 - clksrc-of-ret              => clksrc-of
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

For exynos_mct and samsung_pwm_timer:
Acked-by: NKrzysztof Kozlowski <k.kozlowski@samsung.com>

For arch/arc:
Acked-by: NVineet Gupta <vgupta@synopsys.com>

For mediatek driver:
Acked-by: NMatthias Brugger <matthias.bgg@gmail.com>

For the Rockchip-part
Acked-by: NHeiko Stuebner <heiko@sntech.de>

For STi :
Acked-by: NPatrice Chotard <patrice.chotard@st.com>

For the mps2-timer.c and versatile.c changes:
Acked-by: NLiviu Dudau <Liviu.Dudau@arm.com>

For the OXNAS part :
Acked-by: NNeil Armstrong <narmstrong@baylibre.com>

For LPC32xx driver:
Acked-by: NSylvain Lemieux <slemieux.tyco@gmail.com>

For Broadcom Kona timer change:
Acked-by: NRay Jui <ray.jui@broadcom.com>

For Sun4i and Sun5i:
Acked-by: NChen-Yu Tsai <wens@csie.org>

For Meson6:
Acked-by: NCarlo Caione <carlo@caione.org>

For Keystone:
Acked-by: NSantosh Shilimkar <ssantosh@kernel.org>

For NPS:
Acked-by: NNoam Camus <noamca@mellanox.com>

For bcm2835:
Acked-by: NEric Anholt <eric@anholt.net>

Currently, the clksrc-probe is not able to handle any error from the init
functions. There are different issues with the current code:
 - the code is duplicated in the init functions by writing error
 - every driver tends to panic in its own init function
 - counting the number of clocksources is not reliable

This patch adds another table to store the functions returning an error.
The table is temporary while we convert all the drivers to return an error
and will disappear.
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>

This header uses OF_DELCARE_1 which is defined in linux/of.h.

This fixes getting unhelpful compiler error messages about missing ')'
before a string constant.

Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: NDavid Lechner <david@lechnology.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The clocksource_khz2mult() and clocksource_hz2mult() share similar
code wihch calculates a mult from the given frequency. Both implementations
in differ only in value of a frequency. This patch introduces the
clocksource_freq2mult() helper with generic implementation of
mult calculation to prevent code duplication.
Signed-off-by: NAlexander Kuleshov <kuleshovmail@gmail.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Link: http://lkml.kernel.org/r/1456542854-22104-2-git-send-email-john.stultz@linaro.orgSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

We cache all hotpath members of a clocksource in the time keeper
core. So there is no requirement in general to cache line align struct
clocksource. Remove the enforces alignment.

That allows users which need to wrap struct clocksource into their own
struct to align the struct without getting extra padding.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mans Rullgard <mans@mansr.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Sebastian Frias <sebastian_frias@sigmadesigns.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1511191209000.3898@nanos

Seeing the 'of' characters in a symbol that is being called from
ACPI seems to freak out people. So let's do a bit of pointless
renaming so that these folks do feel at home.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: NHanjun Guo <hanjun.guo@linaro.org>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

It is now absolutely trivial to convert the arch timer driver to
use ACPI probing, just like its DT counterpart.

Let's enjoy another crapectomy.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The clocksource probing infrastructure currently depends on
CONFIG_CLKSRC_OF, which depends on CONFIG_OF. In order to make
this infrastructure selectable even if CONFIG_OF is not selected,
introduce a new CONFIG_CLKSRC_PROBE (which allow the infrastructure
to be compiled in), and CONFIG_CLKSRC_ACPI (which is the pendent
of CONFIG_CLKSRC_OF for ACPI).
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

DT enjoys a rather nice probing infrastructure for clocksources,
while ACPI is so far stuck into a very distant past.

This patch introduces a declarative API, allowing clocksources
to be self-contained and be called when parsing the GTDT table.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The function clocksource_get_next() was removed in commit 75c5158f
(timekeeping: Update clocksource with stop_machine), but the
prototype was not removed with it. Remove the prototype.
Signed-off-by: NYingjoe Chen <yingjoe.chen@mediatek.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <srv_heupstream@mediatek.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/1428674150-1780-1-git-send-email-yingjoe.chen@mediatek.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Using the information presented by GTDT (Generic Timer Description Table)
to initialize the arch timer (not memory-mapped).

CC: Daniel Lezcano <daniel.lezcano@linaro.org>
CC: Thomas Gleixner <tglx@linutronix.de>
Originally-by: NAmit Daniel Kachhap <amit.daniel@samsung.com>
Tested-by: NSuravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Tested-by: NYijing Wang <wangyijing@huawei.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Tested-by: NJon Masters <jcm@redhat.com>
Tested-by: NTimur Tabi <timur@codeaurora.org>
Tested-by: NRobert Richter <rrichter@cavium.com>
Acked-by: NRobert Richter <rrichter@cavium.com>
Acked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: NGrant Likely <grant.likely@linaro.org>
Signed-off-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Ingo requested this function be renamed to improve readability,
so I've renamed __clocksource_updatefreq_scale() as well as the
__clocksource_updatefreq_hz/khz() functions to avoid
squishedtogethernames.

This touches some of the sh clocksources, which I've not tested.

The arch/arm/plat-omap change is just a comment change for
consistency.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-13-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

A long running project has been to clean up remaining uses
of clocksource_register(), replacing it with the simpler
clocksource_register_khz/hz() functions.

However, there are a few cases where we need to self-define
our mult/shift values, so switch the function to a more
obviously internal __clocksource_register() name, and
consolidate much of the internal logic so we don't have
duplication.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-10-git-send-email-john.stultz@linaro.org
[ Minor cleanups. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

In order to facilitate clocksource validation, add a
'max_cycles' field to the clocksource structure which
will hold the maximum cycle value that can safely be
multiplied without potentially causing an overflow.
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-4-git-send-email-john.stultz@linaro.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

The timecounter code has almost nothing to do with the clocksource
code. Let it live in its own file. This will help isolate the
timecounter users from the clocksource users in the source tree.
Signed-off-by: NRichard Cochran <richardcochran@gmail.com>
Acked-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

kernel/time/jiffies.c provides a default clocksource_default_clock()
definition explicitly marked "weak".  arch/s390 provides its own definition
intended to override the default, but the "weak" attribute on the
declaration applied to the s390 definition as well, so the linker chose one
based on link order (see 10629d71 ("PCI: Remove __weak annotation from
pcibios_get_phb_of_node decl")).

Remove the "weak" attribute from the clocksource_default_clock()
declaration so we always prefer a non-weak definition over the weak one,
independent of link order.

Fixes: f1b82746 ("clocksource: Cleanup clocksource selection")
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Acked-by: NJohn Stultz <john.stultz@linaro.org>
Acked-by: NIngo Molnar <mingo@kernel.org>
CC: Daniel Lezcano <daniel.lezcano@linaro.org>
CC: Martin Schwidefsky <schwidefsky@de.ibm.com>

cycle_last was added to the clocksource to support the TSC
validation. We moved that to the core code, so we can get rid of the
extra copy.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

We now have several OF match tables using linker sections that are
nearly the same definition. The only variation is the callback function
prototype. Create a common define for creating linker section OF match
table entries which each table declaration can use.
Acked-by: NGrant Likely <grant.likely@linaro.org>
Signed-off-by: NRob Herring <robh@kernel.org>

We need to calculate the same number in the clocksource code and
the sched_clock code, so extract this code into its own function.
We also drop the min_t and just use min() because the two types
are the same.
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Up to commit 5d33b883 (clocksource: Always verify highres capability)
we had no sanity check when selecting a clocksource, which prevented
that a non highres capable clocksource is used when the system already
switched to highres/nohz mode.

The new sanity check works as Alex and Tim found out. It prevents the
TSC from being used. This happens because on x86 the boot process
looks like this:

 tsc_start_freqency_validation(TSC);
 clocksource_register(HPET);
 clocksource_done_booting();
	clocksource_select()
		Selects HPET which is valid for high-res

 switch_to_highres();

 clocksource_register(TSC);
 	TSC is not selected, because it is not yet
	flagged as VALID_HIGH_RES

 clocksource_watchdog()
	Validates TSC for highres, but that does not make TSC
	the current clocksource.

Before the sanity check was added, we installed TSC unvalidated which
worked most of the time. If the TSC was really detected as unstable,
then the unstable logic removed it and installed HPET again.

The sanity check is correct and needed. So the watchdog needs to kick
a reselection of the clocksource, when it qualifies TSC as a valid
high res clocksource.

To solve this, we mark the clocksource which got the flag
CLOCK_SOURCE_VALID_FOR_HRES set by the watchdog with an new flag
CLOCK_SOURCE_RESELECT and trigger the watchdog thread. The watchdog
thread evaluates the flag and invokes clocksource_select() when set.

To avoid that the clocksource_done_booting() code, which is about to
install the first real clocksource anyway, needs to go through
clocksource_select and tick_oneshot_notify() pointlessly, split out
the clocksource_watchdog_kthread() list walk code and invoke the
select/notify only when called from clocksource_watchdog_kthread().

So clocksource_done_booting() can utilize the same splitout code
without the select/notify invocation and the clocksource_mutex
unlock/relock dance.
Reported-and-tested-by: NAlex Shi <alex.shi@intel.com>
Cc: Hans Peter Anvin <hpa@linux.intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Tested-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: John Stultz <john.stultz@linaro.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1307042239150.11637@ionos.tec.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>

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>

This ensures that a function pointer passed into CLOCKSOURCE_OF_DECLARE
takes the same arguments that we use for calling that function later.

Also fix the extraneous semicolon at end of the CLOCKSOURCE_OF_DECLARE
definition.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NRob Herring <rob.herring@calxeda.com>

This ensures that a function pointer passed into CLOCKSOURCE_OF_DECLARE
takes the same arguments that we use for calling that function later.

Also fix the extraneous semicolon at end of the CLOCKSOURCE_OF_DECLARE
definition.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NRob Herring <rob.herring@calxeda.com>

Some x86 processors have a TSC clocksource, which continues to run
even when system is suspended. Also most OMAP platforms have a
32 KHz timer which has similar capability. Add a feature flag so that
it could be utilized.
Signed-off-by: NFeng Tang <feng.tang@intel.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Add an empty clocksource_of_init when !CLKSRC_OF. This is needed for builds
where no timer has selected CLKSRC_OF.
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

This allows clocksource drivers that support both DT and non-DT to
always invoke macro CLOCKSOURCE_OF_DECLARE(), rather than wrapping
it in a #ifdef CONFIG_CLKSRC_OF, which simplifies their code.
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NOlof Johansson <olof@lixom.net>

It is desirable to move all clocksource drivers to drivers/clocksource,
yet each requires its own initialization function. We'd rather not
pollute <linux/> with a header for each function. Instead, create a
single of_clksrc_init() function which will determine which clocksource
driver to initialize based on device tree.

Based on a similar patch for drivers/irqchip by Thomas Petazzoni.
Signed-off-by: NStephen Warren <swarren@nvidia.com>

Since users will need to include timekeeper_internal.h, move
update_vsyscall definitions to timekeeper_internal.h.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

No one is using this, so encourage the use of
clocksource_register_hz/khz(), and drop this helper.

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NYong Zhang <yong.zhang0@gmail.com>
[jstultz: tweaked commit message]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

Fix various KernelDoc build warnings.
Signed-off-by: NKusanagi Kouichi <slash@ac.auone-net.jp>
Cc: John Stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/20111219091320.0D5AF6FC03D@msa105.auone-net.jpSigned-off-by: NIngo Molnar <mingo@elte.hu>

For some frequencies, the clocks_calc_mult_shift() function will
unfortunately select mult values very close to 0xffffffff.  This
has the potential to overflow when NTP adjusts the clock, adding
to the mult value.

This patch adds a clocksource.maxadj value, which provides
an approximation of an 11% adjustment(NTP limits adjustments to
500ppm and the tick adjustment is limited to 10%), which could
be made to the clocksource.mult value. This is then used to both
check that the current mult value won't overflow/underflow, as
well as warning us if the timekeeping_adjust() code pushes over
that 11% boundary.

v2: Fix max_adjustment calculation, and improve WARN_ONCE
messages.

v3: Don't warn before maxadj has actually been set

CC: Yong Zhang <yong.zhang0@gmail.com>
CC: David Daney <ddaney.cavm@gmail.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Chen Jie <chenj@lemote.com>
CC: zhangfx <zhangfx@lemote.com>
CC: stable@kernel.org
Reported-by: NChen Jie <chenj@lemote.com>
Reported-by: Nzhangfx <zhangfx@lemote.com>
Tested-by: NYong Zhang <yong.zhang0@gmail.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>

The machinery for __ARCH_HAS_CLOCKSOURCE_DATA assumed a file in
asm-generic would be the default for architectures without their own
file in asm/, but that is not how it works.

Replace it with a Kconfig option instead.

Link: http://lkml.kernel.org/r/4E288AA6.7090804@zytor.comSigned-off-by: NH. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@mit.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tony Luck <tony.luck@intel.com>

Now that clocksource.archdata is available, use it for ia64-specific
code.

Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: linux-ia64@vger.kernel.org
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NAndy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/d31de0ee0842a0e322fb6441571c2b0adb323fa2.1310563276.git.luto@mit.eduSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>