Merge tag 'timers-core-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "Time and clocksource/clockevent related updates:

  Core changes:

   - Infrastructure to support per CPU "broadcast" devices for per CPU
     clockevent devices which stop in deep idle states. This allows us
     to utilize the more efficient architected timer on certain ARM SoCs
     for normal operation instead of permanentely using the slow to
     access SoC specific clockevent device.

   - Print the name of the broadcast/wakeup device in /proc/timer_list

   - Make the clocksource watchdog more robust against delays between
     reading the current active clocksource and the watchdog
     clocksource. Such delays can be caused by NMIs, SMIs and vCPU
     preemption.

     Handle this by reading the watchdog clocksource twice, i.e. before
     and after reading the current active clocksource. In case that the
     two watchdog reads shows an excessive time delta, the read sequence
     is repeated up to 3 times.

   - Improve the debug output and add a test module for the watchdog
     mechanism.

   - Reimplementation of the venerable time64_to_tm() function with a
     faster and significantly smaller version. Straight from the source,
     i.e. the author of the related research paper contributed this!

  Driver changes:

   - No new drivers, not even new device tree bindings!

   - Fixes, improvements and cleanups and all over the place"

* tag 'timers-core-2021-06-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
  time/kunit: Add missing MODULE_LICENSE()
  time: Improve performance of time64_to_tm()
  clockevents: Use list_move() instead of list_del()/list_add()
  clocksource: Print deviation in nanoseconds when a clocksource becomes unstable
  clocksource: Provide kernel module to test clocksource watchdog
  clocksource: Reduce clocksource-skew threshold
  clocksource: Limit number of CPUs checked for clock synchronization
  clocksource: Check per-CPU clock synchronization when marked unstable
  clocksource: Retry clock read if long delays detected
  clockevents: Add missing parameter documentation
  clocksource/drivers/timer-ti-dm: Drop unnecessary restore
  clocksource/arm_arch_timer: Improve Allwinner A64 timer workaround
  clocksource/drivers/arm_global_timer: Remove duplicated argument in arm_global_timer
  clocksource/drivers/arm_global_timer: Make symbol 'gt_clk_rate_change_nb' static
  arm: zynq: don't disable CONFIG_ARM_GLOBAL_TIMER due to CONFIG_CPU_FREQ anymore
  clocksource/drivers/arm_global_timer: Implement rate compensation whenever source clock changes
  clocksource/drivers/ingenic: Rename unreasonable array names
  clocksource/drivers/timer-ti-dm: Save and restore timer TIOCP_CFG
  clocksource/drivers/mediatek: Ack and disable interrupts on suspend
  clocksource/drivers/samsung_pwm: Constify source IO memory
  ...

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index a0e1910d0a16..b9e223b08586 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2573,6 +2573,18 @@ config TEST_FPU
 
 	  If unsure, say N.
 
+config TEST_CLOCKSOURCE_WATCHDOG
+	tristate "Test clocksource watchdog in kernel space"
+	depends on CLOCKSOURCE_WATCHDOG
+	help
+	  Enable this option to create a kernel module that will trigger
+	  a test of the clocksource watchdog.  This module may be loaded
+	  via modprobe or insmod in which case it will run upon being
+	  loaded, or it may be built in, in which case it will run
+	  shortly after boot.
+
+	  If unsure, say N.
+
 endif # RUNTIME_TESTING_MENU
 
 config ARCH_USE_MEMTEST