Merge tag 'timers-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "Updates for timekeeping, timers and clockevent/source drivers:

  Core:

   - Yet another round of improvements to make the clocksource watchdog
     more robust:

       - Relax the clocksource-watchdog skew criteria to match the NTP
         criteria.

       - Temporarily skip the watchdog when high memory latencies are
         detected which can lead to false-positives.

       - Provide an option to enable TSC skew detection even on systems
         where TSC is marked as reliable.

     Sigh!

   - Initialize the restart block in the nanosleep syscalls to be
     directed to the no restart function instead of doing a partial
     setup on entry.

     This prevents an erroneous restart_syscall() invocation from
     corrupting user space data. While such a situation is clearly a
     user space bug, preventing this is a correctness issue and caters
     to the least suprise principle.

   - Ignore the hrtimer slack for realtime tasks in schedule_hrtimeout()
     to align it with the nanosleep semantics.

  Drivers:

   - The obligatory new driver bindings for Mediatek, Rockchip and
     RISC-V variants.

   - Add support for the C3STOP misfeature to the RISC-V timer to handle
     the case where the timer stops in deeper idle state.

   - Set up a static key in the RISC-V timer correctly before first use.

   - The usual small improvements and fixes all over the place"

* tag 'timers-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
  clocksource/drivers/timer-sun4i: Add CLOCK_EVT_FEAT_DYNIRQ
  clocksource/drivers/em_sti: Mark driver as non-removable
  clocksource/drivers/sh_tmu: Mark driver as non-removable
  clocksource/drivers/riscv: Patch riscv_clock_next_event() jump before first use
  clocksource/drivers/timer-microchip-pit64b: Add delay timer
  clocksource/drivers/timer-microchip-pit64b: Select driver only on ARM
  dt-bindings: timer: sifive,clint: add comaptibles for T-Head's C9xx
  dt-bindings: timer: mediatek,mtk-timer: add MT8365
  clocksource/drivers/riscv: Get rid of clocksource_arch_init() callback
  clocksource/drivers/sh_cmt: Mark driver as non-removable
  clocksource/drivers/timer-microchip-pit64b: Drop obsolete dependency on COMPILE_TEST
  clocksource/drivers/riscv: Increase the clock source rating
  clocksource/drivers/timer-riscv: Set CLOCK_EVT_FEAT_C3STOP based on DT
  dt-bindings: timer: Add bindings for the RISC-V timer device
  RISC-V: time: initialize hrtimer based broadcast clock event device
  dt-bindings: timer: rk-timer: Add rktimer for rv1126
  time/debug: Fix memory leak with using debugfs_lookup()
  clocksource: Enable TSC watchdog checking of HPET and PMTMR only when requested
  posix-timers: Use atomic64_try_cmpxchg() in __update_gt_cputime()
  clocksource: Verify HPET and PMTMR when TSC unverified
  ...

1 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0ee891133d76..b642b8143fce 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6369,6 +6369,16 @@
 			in situations with strict latency requirements (where
 			interruptions from clocksource watchdog are not
 			acceptable).
+			[x86] recalibrate: force recalibration against a HW timer
+			(HPET or PM timer) on systems whose TSC frequency was
+			obtained from HW or FW using either an MSR or CPUID(0x15).
+			Warn if the difference is more than 500 ppm.
+			[x86] watchdog: Use TSC as the watchdog clocksource with
+			which to check other HW timers (HPET or PM timer), but
+			only on systems where TSC has been deemed trustworthy.
+			This will be suppressed by an earlier tsc=nowatchdog and
+			can be overridden by a later tsc=nowatchdog.  A console
+			message will flag any such suppression or overriding.
 
 	tsc_early_khz=  [X86] Skip early TSC calibration and use the given
 			value instead. Useful when the early TSC frequency discovery