commit 41744213602a206f24adcb4a2b7551db3c700e72 upstream.

The cr16 interval timer of each CPU is not syncronized to other cr16
timers in other CPUs in a SMP system. So, delay the registration of the
cr16 clocksource until all CPUs have been detected and then - if we are
on a SMP machine - mark the cr16 clocksource as unstable and lower it's
rating before registering it at the clocksource framework.

This patch fixes the stalled CPU warnings which we have seen since
introduction of the cr16 clocksource.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Drop the open-coded sched_clock() function and replace it by the provided
GENERIC_SCHED_CLOCK implementation.  We have seen quite some hung tasks in the
past, which seem to be fixed by this patch.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v4.7+
Signed-off-by: Helge Deller <deller@gmx.de>

The config option HAVE_UNSTABLE_SCHED_CLOCK is set automatically when compiling
for SMP. There is no need to clear the stable-clock flag via
clear_sched_clock_stable() when starting secondary CPUs, and even worse,
clearing it triggers wrong self-detected CPU stall warnings on 64bit Mako
machines.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # 4.7+

Commit 54b66800907 (parisc: Add native high-resolution sched_clock()
implementation) added support to use the CPU-internal cr16 counters as reliable
clocksource with the help of HAVE_UNSTABLE_SCHED_CLOCK.

Sadly the commit missed to remove the hack which prevented cr16 to become the
default clocksource even on SMP systems.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org # 4.7+

Pull RTC updates from Alexandre Belloni:
 "RTC for 4.8

  Cleanups:
   - huge cleanup of rtc-generic and char/genrtc this allowed to cleanup
     rtc-cmos, rtc-sh, rtc-m68k, rtc-powerpc and rtc-parisc
   - move mn10300 to rtc-cmos

  Subsystem:
   - fix wakealarms after hibernate
   - multiples fixes for rctest
   - simplify implementations of .read_alarm

  New drivers:
   - Maxim MAX6916

  Drivers:
   - ds1307: fix weekday
   - m41t80: add wakeup support
   - pcf85063: add support for PCF85063A variant
   - rv8803: extend i2c fix and other fixes
   - s35390a: fix alarm reading, this fixes instant reboot after
     shutdown for QNAP TS-41x
   - s3c: clock fixes"

* tag 'rtc-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux: (65 commits)
  rtc: rv8803: Clear V1F when setting the time
  rtc: rv8803: Stop the clock while setting the time
  rtc: rv8803: Always apply the I²C workaround
  rtc: rv8803: Fix read day of week
  rtc: rv8803: Remove the check for valid time
  rtc: rv8803: Kconfig: Indicate rx8900 support
  rtc: asm9260: remove .owner field for driver
  rtc: at91sam9: Fix missing spin_lock_init()
  rtc: m41t80: add suspend handlers for alarm IRQ
  rtc: m41t80: make it a real error message
  rtc: pcf85063: Add support for the PCF85063A device
  rtc: pcf85063: fix year range
  rtc: hym8563: in .read_alarm set .tm_sec to 0 to signal minute accuracy
  rtc: explicitly set tm_sec = 0 for drivers with minute accurancy
  rtc: s3c: Add s3c_rtc_{enable/disable}_clk in s3c_rtc_setfreq()
  rtc: s3c: Remove unnecessary call to disable already disabled clock
  rtc: abx80x: use devm_add_action_or_reset()
  rtc: m41t80: use devm_add_action_or_reset()
  rtc: fix a typo and reduce three empty lines to one
  rtc: s35390a: improve two comments in .set_alarm
  ...

Avoid showing invalid printk time stamps during boot.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Aaro Koskinen <aaro.koskinen@iki.fi>

The rtc-generic driver provides an architecture specific
wrapper on top of the generic rtc_class_ops abstraction,
and on pa-risc, that is implemented using an open-coded
version of rtc_time_to_tm/rtc_tm_to_time.

This changes the parisc rtc-generic device to provide its
rtc_class_ops directly, using the normal helper functions,
which makes this y2038 safe (on 32-bit) and simplifies
the implementation.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

Add a native implementation for the sched_clock() function which utilizes the
processor-internal cycle counter (Control Register 16) as high-resolution time
source.

With this patch we now get much more fine-grained resolutions in various
in-kernel time measurements (e.g. when viewing the function tracing logs), and
probably a more accurate scheduling on SMP systems.

There are a few specific implementation details in this patch:

1. On a 32bit kernel we emulate the higher 32bits of the required 64-bit
resolution of sched_clock() by increasing a per-cpu counter at every
wrap-around of the 32bit cycle counter.

2. In a SMP system, the cycle counters of the various CPUs are not syncronized
(similiar to the TSC in a x86_64 system). To cope with this we define
HAVE_UNSTABLE_SCHED_CLOCK and let the upper layers do the adjustment work.

3. Since we need HAVE_UNSTABLE_SCHED_CLOCK, we need to provide a cmpxchg64()
function even on a 32-bit kernel.

4. A 64-bit SMP kernel which is started on a UP system will mark the
sched_clock() implementation as "stable", which means that we don't expect any
jumps in the returned counter. This is true because we then run only on one
CPU.

Signed-off-by: Helge Deller <deller@gmx.de>

Signed-off-by: Helge Deller <deller@gmx.de>

No need to use CONFIG_SMP around update_cr16_clocksource(). It checks for
num_online_cpus() beeing greater than 1, which is always 1 in UP builds.

Signed-off-by: Helge Deller <deller@gmx.de>