kernel/linux.git/include/linux/timekeeping.h, branch v6.12.80

timekeeping: Add function to convert realtime to base clock

2024-06-03T09:18:51+00:00

PPS (Pulse Per Second) generates a hardware pulse every second based on CLOCK_REALTIME. This works fine when the pulse is generated in software from a hrtimer callback function. For hardware which generates the pulse by programming a timer it is required to convert CLOCK_REALTIME to the underlying hardware clock. The X86 Timed IO device is based on the Always Running Timer (ART), which is the base clock of the TSC, which is usually the system clocksource on X86. The core code already has functionality to convert base clock timestamps to system clocksource timestamps, but there is no support for converting the other way around. Provide the required functionality to support such devices in a generic way to avoid code duplication in drivers: 1) ktime_real_to_base_clock() to convert a CLOCK_REALTIME timestamp to a base clock timestamp 2) timekeeping_clocksource_has_base() to allow drivers to validate that the system clocksource is based on a particular clocksource ID. [ tglx: Simplify timekeeping_clocksource_has_base() and add missing READ_ONCE() ] Co-developed-by: Thomas Gleixner Signed-off-by: Thomas Gleixner Co-developed-by: Christopher S. Hall Signed-off-by: Christopher S. Hall Signed-off-by: Lakshmi Sowjanya D Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240513103813.5666-10-lakshmi.sowjanya.d@intel.com

timekeeping: Provide infrastructure for converting to/from a base clock

2024-06-03T09:18:50+00:00

Hardware time stamps like provided by PTP clock implementations are based on a clock which feeds both the PCIe device and the system clock. For further processing the underlying hardwarre clock timestamp must be converted to the system clock. Right now this requires drivers to invoke an architecture specific conversion function, e.g. to convert the ART (Always Running Timer) timestamp to a TSC timestamp. As the system clock is aware of the underlying base clock, this can be moved to the core code by providing a base clock property for the system clock which contains the conversion factors and assigning a clocksource ID to the base clock. Add the required data structures and the conversion infrastructure in the core code to prepare for converting X86 and the related PTP drivers over. [ tglx: Added a missing READ_ONCE(). Massaged change log ] Co-developed-by: Thomas Gleixner Signed-off-by: Thomas Gleixner Co-developed-by: Christopher S. Hall Signed-off-by: Christopher S. Hall Signed-off-by: Lakshmi Sowjanya D Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240513103813.5666-2-lakshmi.sowjanya.d@intel.com

time/timekeeping: Fix kernel-doc warnings and typos

2024-04-01T08:36:34+00:00

Fix punctuation, spellos, and kernel-doc warnings: timekeeping.h:79: warning: No description found for return value of 'ktime_get_real' timekeeping.h:95: warning: No description found for return value of 'ktime_get_boottime' timekeeping.h:108: warning: No description found for return value of 'ktime_get_clocktai' timekeeping.h:149: warning: Function parameter or struct member 'mono' not described in 'ktime_mono_to_real' timekeeping.h:149: warning: No description found for return value of 'ktime_mono_to_real' timekeeping.h:255: warning: Function parameter or struct member 'cs_id' not described in 'system_time_snapshot' Signed-off-by: Randy Dunlap Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20240331172652.14086-3-rdunlap@infradead.org

treewide: Remove system_counterval_t.cs, which is never read

2024-02-07T16:05:21+00:00

The clocksource pointer in struct system_counterval_t is not evaluated any more. Remove the code setting the member, and the member itself. Signed-off-by: Peter Hilber Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240201010453.2212371-8-peter.hilber@opensynergy.com

timekeeping: Evaluate system_counterval_t.cs_id instead of .cs

2024-02-07T16:05:21+00:00

Clocksource pointers can be problematic to obtain for drivers which are not clocksource drivers themselves. In particular, the RFC virtio_rtc driver [1] would require a new helper function to obtain a pointer to the ARM Generic Timer clocksource. The ptp_kvm driver also required a similar workaround. Address this by evaluating the clocksource ID, rather than the clocksource pointer, of struct system_counterval_t. By this, setting the clocksource pointer becomes unneeded, and get_device_system_crosststamp() callers will no longer need to supply clocksource pointers. All relevant clocksource drivers provide the ID, so this change is not changing the behaviour. [1] https://lore.kernel.org/lkml/20231218073849.35294-1-peter.hilber@opensynergy.com/ Signed-off-by: Peter Hilber Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240201010453.2212371-7-peter.hilber@opensynergy.com

timekeeping: Add clocksource ID to struct system_counterval_t

2024-02-07T16:05:21+00:00

Clocksource pointers can be problematic to obtain for drivers which are not clocksource drivers themselves. In particular, the RFC virtio_rtc driver [1] would require a new helper function to obtain a pointer to the ARM Generic Timer clocksource. The ptp_kvm driver also required a similar workaround. Add a clocksource ID member to struct system_counterval_t, which in the future shall identify the clocksource, and which shall replace the struct clocksource * member. By this, get_device_system_crosststamp() callers (such as virtio_rtc and ptp_kvm) will be able to supply easily accessible clocksource ids instead of clocksource pointers. [1] https://lore.kernel.org/lkml/20231218073849.35294-1-peter.hilber@opensynergy.com/ Signed-off-by: Peter Hilber Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240201010453.2212371-3-peter.hilber@opensynergy.com

workqueue: Split out workqueue_types.h

2023-12-21T00:26:31+00:00

More sched.h dependency culling - this lets us kill a rhashtable-types.h dependency on workqueue.h. Signed-off-by: Kent Overstreet

timekeeping: Introduce fast accessor to clock tai

2022-04-14T14:19:30+00:00

Introduce fast/NMI safe accessor to clock tai for tracing. The Linux kernel tracing infrastructure has support for using different clocks to generate timestamps for trace events. Especially in TSN networks it's useful to have TAI as trace clock, because the application scheduling is done in accordance to the network time, which is based on TAI. With a tai trace_clock in place, it becomes very convenient to correlate network activity with Linux kernel application traces. Use the same implementation as ktime_get_boot_fast_ns() does by reading the monotonic time and adding the TAI offset. The same limitations as for the fast boot implementation apply. The TAI offset may change at run time e.g., by setting the time or using adjtimex() with an offset. However, these kind of offset changes are rare events. Nevertheless, the user has to be aware and deal with it in post processing. An alternative approach would be to use the same implementation as ktime_get_real_fast_ns() does. However, this requires to add an additional u64 member to the tk_read_base struct. This struct together with a seqcount is designed to fit into a single cache line on 64 bit architectures. Adding a new member would violate this constraint. Signed-off-by: Kurt Kanzenbach Signed-off-by: Thomas Gleixner Cc: Steven Rostedt Link: https://lore.kernel.org/r/20220414091805.89667-2-kurt@linutronix.de

time: Add mechanism to recognize clocksource in time_get_snapshot

2021-04-07T15:33:20+00:00

System time snapshots are not conveying information about the current clocksource which was used, but callers like the PTP KVM guest implementation have the requirement to evaluate the clocksource type to select the appropriate mechanism. Introduce a clocksource id field in struct clocksource which is by default set to CSID_GENERIC (0). Clocksource implementations can set that field to a value which allows to identify the clocksource. Store the clocksource id of the current clocksource in the system_time_snapshot so callers can evaluate which clocksource was used to take the snapshot and act accordingly. Signed-off-by: Thomas Gleixner Signed-off-by: Jianyong Wu Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20201209060932.212364-5-jianyong.wu@arm.com

Merge tag 'asm-generic-timers-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

2020-12-16T08:07:17+00:00

Pull asm-generic cross-architecture timer cleanup from Arnd Bergmann: "This cleans up two ancient timer features that were never completed in the past, CONFIG_GENERIC_CLOCKEVENTS and CONFIG_ARCH_USES_GETTIMEOFFSET. There was only one user left for the ARCH_USES_GETTIMEOFFSET variant of clocksource implementations, the ARM EBSA110 platform. Rather than changing to use modern timekeeping, we remove the platform entirely as Russell no longer uses his machine and nobody else seems to have one any more. The conditional code for using arch_gettimeoffset() is removed as a result. For CONFIG_GENERIC_CLOCKEVENTS, there are still a couple of platforms not using clockevent drivers: parisc, ia64, most of m68k, and one Arm platform. These all do timer ticks slighly differently, and this gets cleaned up to the point they at least all call the same helper function. Instead of most platforms using 'select GENERIC_CLOCKEVENTS' in Kconfig, the polarity is now reversed, with the few remaining ones selecting LEGACY_TIMER_TICK instead" * tag 'asm-generic-timers-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic: timekeeping: default GENERIC_CLOCKEVENTS to enabled timekeeping: remove xtime_update m68k: remove timer_interrupt() function m68k: change remaining timers to legacy_timer_tick m68k: m68328: use legacy_timer_tick() m68k: sun3/sun3c: use legacy_timer_tick m68k: split heartbeat out of timer function m68k: coldfire: use legacy_timer_tick() parisc: use legacy_timer_tick ARM: rpc: use legacy_timer_tick ia64: convert to legacy_timer_tick timekeeping: add CONFIG_LEGACY_TIMER_TICK timekeeping: remove arch_gettimeoffset net: remove am79c961a driver ARM: remove ebsa110 platform