linux.git/arch/parisc/kernel/time.c, branch v5.17

parisc: Mark cr16 CPU clocksource unstable on all SMP machines

2021-12-04T20:36:04+00:00

In commit c8c3735997a3 ("parisc: Enhance detection of synchronous cr16
clocksources") I assumed that CPUs on the same physical core are syncronous.
While booting up the kernel on two different C8000 machines, one with a
dual-core PA8800 and one with a dual-core PA8900 CPU, this turned out to be
wrong. The symptom was that I saw a jump in the internal clocks printed to the
syslog and strange overall behaviour.  On machines which have 4 cores (2
dual-cores) the problem isn't visible, because the current logic already marked
the cr16 clocksource unstable in this case.

This patch now marks the cr16 interval timers unstable if we have more than one
CPU in the system, and it fixes this issue.

Fixes: c8c3735997a3 ("parisc: Enhance detection of synchronous cr16 clocksources")
Signed-off-by: Helge Deller 
Cc:  # v5.15+

parisc: Mark sched_clock unstable only if clocks are not syncronized

2021-09-09T10:44:31+00:00

We check at runtime if the cr16 clocks are stable across CPUs. Only mark
the sched_clock unstable by calling clear_sched_clock_stable() if we
know that we run on a system which isn't syncronized across CPUs.

Signed-off-by: Helge Deller

parisc: use legacy_timer_tick

2020-10-30T20:57:05+00:00

parisc has selected CONFIG_GENERIC_CLOCKEVENTS since commit 43b1f6abd590
("parisc: Switch to generic sched_clock implementation"), but does not
appear to actually be using it, and instead calls the low-level
timekeeping functions directly.

Remove the GENERIC_CLOCKEVENTS select again, and instead convert to
the newly added legacy_timer_tick() helper.

Reviewed-by: Linus Walleij 
Signed-off-by: Arnd Bergmann

parisc: Improve error return codes when setting rtc time

2020-10-22T20:44:27+00:00

The HP 730 machine returned strange errors when I tried setting the rtc
time.  Add some debug code to improve the possibility to trace errors
and document that hppa probably has as Y2k38 problem.

Signed-off-by: Helge Deller

parisc: Use __ro_after_init in time.c

2019-05-10T19:00:45+00:00

Signed-off-by: Helge Deller

parisc: time: Convert read_persistent_clock() to read_persistent_clock64()

2018-04-20T18:18:21+00:00

The read_persistent_clock() uses a timespec, which is not year 2038 safe
on 32bit systems. On parisc architecture, we have implemented generic
RTC drivers that can be used to compensate the system suspend time, but
the RTC time can not represent the nanosecond resolution, so this patch
just converts to read_persistent_clock64() with timespec64.

Signed-off-by: Baolin Wang 
Acked-by: Arnd Bergmann 
Signed-off-by: Helge Deller

Merge tag 'rtc-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux

2018-04-10T17:22:27+00:00

Pull RTC updates from Alexandre Belloni:
 "This contains a few series that have been in preparation for a while
  and that will help systems with RTCs that will fail in 2038, 2069 or
  2100.

  Subsystem:
   - Add tracepoints
   - Rework of the RTC/nvmem API to allow drivers to discard struct
     nvmem_config after registration
   - New range API, drivers can now expose the useful range of the RTC
   - New offset API the core is now able to add an offset to the RTC
     time, modifying the supported range.
   - Multiple rtc_time64_to_tm fixes
   - Handle time_t overflow on 32 bit platforms in the core instead of
     letting drivers do crazy things.
   - remove rtc_control API

  New driver:
   - Intersil ISL12026

  Drivers:
   - Drivers exposing the RTC non volatile memory have been converted to
     use nvmem
   - Removed useless time and date validation
   - Removed an indirection pattern that was a cargo cult from ancient
     drivers
   - Removed VLA usage
   - Fixed a possible race condition in probe functions
   - AB8540 support is dropped from ab8500
   - pcf85363 now has alarm support"

* tag 'rtc-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/abelloni/linux: (128 commits)
  rtc: snvs: Fix usage of snvs_rtc_enable
  rtc: mt7622: fix module autoloading for OF platform drivers
  rtc: isl12022: use true and false for boolean values
  rtc: ab8500: Drop AB8540 support
  rtc: remove a warning during scripts/kernel-doc step
  rtc: 88pm860x: remove artificial limitation
  rtc: 88pm80x: remove artificial limitation
  rtc: st-lpc: remove artificial limitation
  rtc: mrst: remove artificial limitation
  rtc: mv: remove artificial limitation
  rtc: hctosys: Ensure system time doesn't overflow time_t
  parisc: time: stop validating rtc_time in .read_time
  rtc: pcf85063: fix clearing bits in pcf85063_start_clock
  rtc: at91sam9: Set name of regmap_config
  rtc: s5m: Remove VLA usage
  rtc: s5m: Move enum from rtc.h to rtc-s5m.c
  rtc: remove VLA usage
  rtc: Add useful timestamp definitions
  rtc: Add one offset seconds to expand RTC range
  rtc: Factor out the RTC range validation into rtc_valid_range()
  ...

parisc: time: stop validating rtc_time in .read_time

2018-03-19T23:02:09+00:00

The RTC core is always calling rtc_valid_tm after the read_time callback.
It is not necessary to call it just before returning from the callback.

Signed-off-by: Alexandre Belloni 
Acked-by: Helge Deller 
Signed-off-by: Alexandre Belloni

parisc: Reduce irq overhead when run in qemu

2018-03-02T09:05:07+00:00

When run under QEMU, calling mfctl(16) creates some overhead because the
qemu timer has to be scaled and moved into the register. This patch
reduces the number of calls to mfctl(16) by moving the calls out of the
loops.

Additionally, increase the minimal time interval to 8000 cycles instead
of 500 to compensate possible QEMU delays when delivering interrupts.

Signed-off-by: Helge Deller 
Cc: stable@vger.kernel.org # 4.14+

parisc: Use cr16 interval timers unconditionally on qemu

2018-03-02T09:04:59+00:00

When running on qemu we know that the (emulated) cr16 cpu-internal
clocks are syncronized. So let's use them unconditionally on qemu.

Signed-off-by: Helge Deller 
Cc: stable@vger.kernel.org # 4.14+