linux-toradex.git/arch/powerpc/kernel/time.c, branch v4.2.7

powerpc: use device_initcall for registering rtc devices

2015-06-16T18:12:29+00:00

Currently these two RTC devices are in core platform code
where it is not possible for them to be modular.  It will
never be modular, so using module_init as an alias for
__initcall can be somewhat misleading.

Fix this up now, so that we can relocate module_init from
init.h into module.h in the future.  If we don't do this, we'd
have to add module.h to obviously non-modular code, and that
would be a worse thing.

Note that direct use of __initcall is discouraged, vs. one
of the priority categorized subgroups.  As __initcall gets
mapped onto device_initcall, our use of device_initcall
directly in this change means that the runtime impact is
zero -- they will remain at level 6 in initcall ordering.

Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Geoff Levand 
Acked-by: Geoff Levand 
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Paul Gortmaker

KVM: PPC: Book3S HV: Accumulate timing information for real-mode code

2015-04-21T13:21:31+00:00

This reads the timebase at various points in the real-mode guest
entry/exit code and uses that to accumulate total, minimum and
maximum time spent in those parts of the code.  Currently these
times are accumulated per vcpu in 5 parts of the code:

* rm_entry - time taken from the start of kvmppc_hv_entry() until
  just before entering the guest.
* rm_intr - time from when we take a hypervisor interrupt in the
  guest until we either re-enter the guest or decide to exit to the
  host.  This includes time spent handling hcalls in real mode.
* rm_exit - time from when we decide to exit the guest until the
  return from kvmppc_hv_entry().
* guest - time spend in the guest
* cede - time spent napping in real mode due to an H_CEDE hcall
  while other threads in the same vcore are active.

These times are exposed in debugfs in a directory per vcpu that
contains a file called "timings".  This file contains one line for
each of the 5 timings above, with the name followed by a colon and
4 numbers, which are the count (number of times the code has been
executed), the total time, the minimum time, and the maximum time,
all in nanoseconds.

The overhead of the extra code amounts to about 30ns for an hcall that
is handled in real mode (e.g. H_SET_DABR), which is about 25%.  Since
production environments may not wish to incur this overhead, the new
code is conditional on a new config symbol,
CONFIG_KVM_BOOK3S_HV_EXIT_TIMING.

Signed-off-by: Paul Mackerras 
Signed-off-by: Alexander Graf

Merge tag 'clk-for-linus-3.20' of git://git.linaro.org/people/mike.turquette/linux

2015-02-21T20:30:30+00:00

Pull clock framework updates from Mike Turquette:
 "The clock framework changes contain the usual driver additions,
  enhancements and fixes mostly for ARM32, ARM64, MIPS and Power-based
  devices.

  Additionally the framework core underwent a bit of surgery with two
  major changes:

   - The boundary between the clock core and clock providers (e.g clock
     drivers) is now more well defined with dedicated provider helper
     functions.  struct clk no longer maps 1:1 with the hardware clock
     but is a true per-user cookie which helps us tracker users of
     hardware clocks and debug bad behavior.

   - The addition of rate constraints for clocks.  Rate ranges are now
     supported which are analogous to the voltage ranges in the
     regulator framework.

  Unfortunately these changes to the core created some breakeage.  We
  think we fixed it all up but for this reason there are lots of last
  minute commits trying to undo the damage"

* tag 'clk-for-linus-3.20' of git://git.linaro.org/people/mike.turquette/linux: (113 commits)
  clk: Only recalculate the rate if needed
  Revert "clk: mxs: Fix invalid 32-bit access to frac registers"
  clk: qoriq: Add support for the platform PLL
  powerpc/corenet: Enable CLK_QORIQ
  clk: Replace explicit clk assignment with __clk_hw_set_clk
  clk: Add __clk_hw_set_clk helper function
  clk: Don't dereference parent clock if is NULL
  MIPS: Alchemy: Remove bogus args from alchemy_clk_fgcs_detr
  clkdev: Always allocate a struct clk and call __clk_get() w/ CCF
  clk: shmobile: div6: Avoid division by zero in .round_rate()
  clk: mxs: Fix invalid 32-bit access to frac registers
  clk: omap: compile legacy omap3 clocks conditionally
  clkdev: Export clk_register_clkdev
  clk: Add rate constraints to clocks
  clk: remove clk-private.h
  pci: xgene: do not use clk-private.h
  arm: omap2+ remove dead clock code
  clk: Make clk API return per-user struct clk instances
  clk: tegra: Define PLLD_DSI and remove dsia(b)_mux
  clk: tegra: Add support for the Tegra132 CAR IP block
  ...

powerpc: add running_clock for powerpc to prevent spurious softlockup warnings

2015-02-13T02:54:13+00:00

On POWER8 virtualised kernels the VTB register can be read to have a view
of time that only increases while the guest is running.  This will prevent
guests from seeing time jump if a guest is paused for significant amounts
of time.

On POWER7 and below virtualised kernels stolen time is subtracted from
local_clock as a best effort approximation.  This will not eliminate
spurious warnings in the case of a suspended guest but may reduce the
occurance in the case of softlockups due to host over commit.

Bare metal kernels should avoid reading the VTB as KVM does not restore
sane values when not executing, the approxmation is fine as host kernels
won't observe any stolen time.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Cyril Bur 
Cc: Michael Ellerman 
Cc: Andrew Jones 
Acked-by: Don Zickus 
Cc: Ingo Molnar 
Cc: Ulrich Obergfell 
Cc: chai wen 
Cc: Fabian Frederick 
Cc: Aaron Tomlin 
Cc: Ben Zhang 
Cc: Martin Schwidefsky 
Cc: John Stultz 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc: call of_clk_init() from time_init()

2015-01-20T18:09:02+00:00

So the boards which has COMMON_CLK enabled don't have to
invoke this in its board specific file.

Signed-off-by: Kevin Hao 
Acked-by: Scott Wood 
Acked-by: Michael Turquette 
Signed-off-by: Michael Turquette

rtc/tpo: Driver to support rtc and wakeup on PowerNV platform

2014-11-17T07:04:01+00:00

The patch implements the OPAL rtc driver that binds with the rtc
driver subsystem. The driver uses the platform device infrastructure
to probe the rtc device and register it to rtc class framework. The
'wakeup' is supported depending upon the property 'has-tpo' present
in the OF node. It provides a way to load the generic rtc driver in
in the absence of an OPAL driver.

The patch also moves the existing OPAL rtc get/set time interfaces to the
new driver and exposes the necessary OPAL calls using EXPORT_SYMBOL_GPL.

Test results:
-------------
Host:
[root@tul169p1 ~]# ls -l /sys/class/rtc/
total 0
lrwxrwxrwx 1 root root 0 Oct 14 03:07 rtc0 -> ../../devices/opal-rtc/rtc/rtc0
[root@tul169p1 ~]# cat /sys/devices/opal-rtc/rtc/rtc0/time
08:10:07
[root@tul169p1 ~]# echo `date '+%s' -d '+ 2 minutes'` > /sys/class/rtc/rtc0/wakealarm
[root@tul169p1 ~]# cat /sys/class/rtc/rtc0/wakealarm
1413274345
[root@tul169p1 ~]#

FSP:
$ smgr mfgState
standby
$ rtim timeofday

System time is valid: 2014/10/14 08:12:04.225115

$ smgr mfgState
ipling
$

CC: devicetree@vger.kernel.org
CC: tglx@linutronix.de
CC: rtc-linux@googlegroups.com
CC: a.zummo@towertech.it
Signed-off-by: Neelesh Gupta 
Signed-off-by: Michael Ellerman

powerpc: Replace __get_cpu_var uses

2014-11-03T01:12:32+00:00

This still has not been merged and now powerpc is the only arch that does
not have this change. Sorry about missing linuxppc-dev before.

V2->V2
  - Fix up to work against 3.18-rc1

__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e.  using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&x, this_cpu_ptr(&y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	__this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	__this_cpu_inc(y)

Cc: Benjamin Herrenschmidt 
CC: Paul Mackerras 
Signed-off-by: Christoph Lameter 
[mpe: Fix build errors caused by set/or_softirq_pending(), and rework
      assignment in __set_breakpoint() to use memcpy().]
Signed-off-by: Michael Ellerman

powerpc: Make a bunch of things static

2014-09-25T13:14:41+00:00

Signed-off-by: Anton Blanchard 
Signed-off-by: Michael Ellerman

powerpc: Move more symbol exports next to function definitions

2014-09-25T13:14:38+00:00

Signed-off-by: Anton Blanchard 
Signed-off-by: Michael Ellerman

clocksource: Get rid of cycle_last

2014-07-23T22:01:52+00:00

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: Thomas Gleixner 
Signed-off-by: John Stultz