linux.git/include/linux/timekeeping.h, branch v7.2-rc1 Linux kernel source tree timekeeping: Add clocksource read_snapshot() method and hw_cycles to snapshot 2026-06-04T09:04:18+00:00 David Woodhouse dwmw@amazon.co.uk 2026-05-29T20:01:29+00:00 ca1ec8bfac8c95d0fed9e3611ea21400d1f37262 Add a read_snapshot() callback to struct clocksource which returns the derived clocksource value while also providing the underlying hardware counter reading and the related clocksource ID. This allows ktime_get_snapshot_id() to populate new hw_cycles and hw_csid fields in struct system_time_snapshot. For clocksources that are derived from an underlying counter (e.g., Hyper-V TSC page scales TSC to 10MHz, kvmclock scales TSC to 1GHz), this provides atomic access to both the derived value needed for timekeeping calculations, and the raw hardware counter needed by consumers like KVM's master clock and the vmclock PTP driver. [ tglx: Reworked it slightly ] Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Signed-off-by: Thomas Gleixner <tglx@kernel.org> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Assisted-by: Kiro:claude-opus-4.6-1m Link: https://patch.msgid.link/20260526230635.136914-1-dwmw2@infradead.org Link: https://patch.msgid.link/20260529195558.202568489@kernel.org 
Add a read_snapshot() callback to struct clocksource which returns the
derived clocksource value while also providing the underlying hardware
counter reading and the related clocksource ID.

This allows ktime_get_snapshot_id() to populate new hw_cycles and hw_csid
fields in struct system_time_snapshot.

For clocksources that are derived from an underlying counter (e.g., Hyper-V
TSC page scales TSC to 10MHz, kvmclock scales TSC to 1GHz), this provides
atomic access to both the derived value needed for timekeeping
calculations, and the raw hardware counter needed by consumers like KVM's
master clock and the vmclock PTP driver.

[ tglx: Reworked it slightly ]

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Assisted-by: Kiro:claude-opus-4.6-1m
Link: https://patch.msgid.link/20260526230635.136914-1-dwmw2@infradead.org
Link: https://patch.msgid.link/20260529195558.202568489@kernel.org
timekeeping: Remove system_device_crosststamp::sys_realtime 2026-06-04T09:04:17+00:00 Thomas Gleixner tglx@kernel.org 2026-05-29T20:01:17+00:00 5ccaf1e569f04d8fd5f0167be728fdb48f448f81 All users are converted to sys_systime. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: David Woodhouse <dwmw@amazon.co.uk> Tested-by: Arthur Kiyanovski <akiyano@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://patch.msgid.link/20260529195558.046694580@kernel.org 
All users are converted to sys_systime.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195558.046694580@kernel.org
timekeeping: Prepare for cross timestamps on arbitrary clock IDs 2026-06-04T09:04:17+00:00 Thomas Gleixner tglx@kernel.org 2026-05-29T20:01:00+00:00 09fb74f77e02489d1d8c555d44bab99d4905127c PTP device system crosstime stamps support only CLOCK_REALTIME, which is meaningless for AUX clocks. The PTP core hands in the clock ID already, so prepare the core code to honor it. - Add a new sys_systime field to struct system_device_crosststamp which aliases the sys_realtime field. Once all users are converted sys_realtime can be removed. - Prepare get_device_system_crosststamp() and the related code for it by switching to sys_systime and providing the initial changes to utilize different time keepers. No functional change intended. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: David Woodhouse <dwmw@amazon.co.uk> Tested-by: Arthur Kiyanovski <akiyano@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://patch.msgid.link/20260529195557.846634842@kernel.org 
PTP device system crosstime stamps support only CLOCK_REALTIME, which is
meaningless for AUX clocks. The PTP core hands in the clock ID already, so
prepare the core code to honor it.

 - Add a new sys_systime field to struct system_device_crosststamp which
   aliases the sys_realtime field. Once all users are converted
   sys_realtime can be removed.

 - Prepare get_device_system_crosststamp() and the related code for it by
   switching to sys_systime and providing the initial changes to utilize
   different time keepers.

No functional change intended.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.846634842@kernel.org
timekeeping: Remove ktime_get_snapshot() 2026-06-04T09:04:17+00:00 Thomas Gleixner tglx@kernel.org 2026-05-29T20:00:56+00:00 b21d442c9aebe5ed95303883d3365e430e134cf1 All users have been converted to ktime_get_snapshot_id(). Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: David Woodhouse <dwmw@amazon.co.uk> Tested-by: Arthur Kiyanovski <akiyano@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://patch.msgid.link/20260529195557.795510496@kernel.org 
All users have been converted to ktime_get_snapshot_id().

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.795510496@kernel.org
timekeeping: Add CLOCK ID to system_device_crosststamp 2026-06-04T09:04:16+00:00 Thomas Gleixner tglx@kernel.org 2026-05-29T20:00:32+00:00 e3b8d03faa4d266d19ff7a7534e7bf810ff681cf The normal capture for system/device cross timestamps is CLOCK_REALTIME, but that's meaningless for AUX clocks. Add a clock_id field to struct system_device_crosststamp and initialize it with CLOCK_REALTIME at the two places which prepare for cross timestamps. After the related code has been cleaned up, the core code will honor the clock_id field when calculating the system time from the system counter snapshot. No functional change. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: David Woodhouse <dwmw@amazon.co.uk> Tested-by: Arthur Kiyanovski <akiyano@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://patch.msgid.link/20260529195557.482153523@kernel.org 
The normal capture for system/device cross timestamps is CLOCK_REALTIME,
but that's meaningless for AUX clocks.

Add a clock_id field to struct system_device_crosststamp and initialize it
with CLOCK_REALTIME at the two places which prepare for cross
timestamps.

After the related code has been cleaned up, the core code will honor the
clock_id field when calculating the system time from the system counter
snapshot.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.482153523@kernel.org
timekeeping: Add system_counterval_t to struct system_device_crosststamp 2026-06-04T09:04:16+00:00 Thomas Gleixner tglx@kernel.org 2026-05-29T20:00:28+00:00 6c14771816435a7ecf52d981a341e2de21463268 An upcoming extension to the PTP IOCTL requires to return the system counter value and the clocksource ID to user space. get_device_system_crosststamp() has this information already. Extend struct system_device_crosststamp with a system_counterval_t member and fill in the data. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: David Woodhouse <dwmw@amazon.co.uk> Tested-by: Arthur Kiyanovski <akiyano@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://patch.msgid.link/20260529195557.429406675@kernel.org 
An upcoming extension to the PTP IOCTL requires to return the system counter
value and the clocksource ID to user space. get_device_system_crosststamp() has
this information already.

Extend struct system_device_crosststamp with a system_counterval_t member
and fill in the data.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.429406675@kernel.org
timekeeping: Remove system_time_snapshot::real/boot/raw 2026-06-04T09:04:16+00:00 Thomas Gleixner tglx@kernel.org 2026-05-29T20:00:20+00:00 705e1068071f82b6c66b9e28124fbb7123b04c1d All users are converted over to ktime_get_snapshot_id() and system_time_snapshot::systime and ::monoraw. Remove the leftovers. Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: David Woodhouse <dwmw@amazon.co.uk> Tested-by: Arthur Kiyanovski <akiyano@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://patch.msgid.link/20260529195557.330029635@kernel.org 
All users are converted over to ktime_get_snapshot_id() and
system_time_snapshot::systime and ::monoraw.

Remove the leftovers.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195557.330029635@kernel.org
timekeeping: Provide ktime_get_snapshot_id() 2026-06-02T09:39:57+00:00 Thomas Gleixner tglx@kernel.org 2026-05-29T19:59:51+00:00 eba302268a019275fd6ff452d4ff0b94fef11c76 ktime_get_snapshot() provides a snapshot of the underlying clocksource counter value and the corresponding CLOCK_MONOTONIC_RAW, CLOCK_REALTIME and CLOCK_BOOTTIME timestamps. There is no usage of CLOCK_REALTIME and CLOCK_BOOTTIME at the same time and CLOCK_BOOTTIME support was just added for the ARM64 KVM tracing mechanism, which needs CLOCK_BOOTTIME and the underlying clocksource counter value. ktime_get_snapshot() is also not suitable for usage with CLOCK_AUX, but that's a prerequisite to support PTP hardware timestamping for CLOCK_AUX steering. As a first step, rename ktime_get_snapshot() to ktime_get_snapshot_id(), which now takes a clockid argument to select the clock which needs to be captured. The result is stored in system_time_snapshot::systime, which will replace the system_time_snapshot::real/boot members once all usage sites have been converted. ktime_get_snapshot() is a simple wrapper which hands in CLOCK_REALTIME as clockid argument for the conversion period. That means CLOCK_REALTIME is now captured twice, but that redunancy is only temporary. As all usage sites of struct system_time_snapshot has to be updated anyway, rename the 'raw' member to 'monoraw' for clarity. No functional change vs. current users of ktime_get_snapshot() Signed-off-by: Thomas Gleixner <tglx@kernel.org> Tested-by: David Woodhouse <dwmw@amazon.co.uk> Tested-by: Arthur Kiyanovski <akiyano@amazon.com> Reviewed-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Link: https://patch.msgid.link/20260529195556.971591633@kernel.org 
ktime_get_snapshot() provides a snapshot of the underlying clocksource
counter value and the corresponding CLOCK_MONOTONIC_RAW, CLOCK_REALTIME and
CLOCK_BOOTTIME timestamps.

There is no usage of CLOCK_REALTIME and CLOCK_BOOTTIME at the same time and
CLOCK_BOOTTIME support was just added for the ARM64 KVM tracing mechanism,
which needs CLOCK_BOOTTIME and the underlying clocksource counter value.

ktime_get_snapshot() is also not suitable for usage with CLOCK_AUX, but
that's a prerequisite to support PTP hardware timestamping for CLOCK_AUX
steering.

As a first step, rename ktime_get_snapshot() to ktime_get_snapshot_id(),
which now takes a clockid argument to select the clock which needs to be
captured. The result is stored in system_time_snapshot::systime, which will
replace the system_time_snapshot::real/boot members once all usage sites
have been converted.

ktime_get_snapshot() is a simple wrapper which hands in CLOCK_REALTIME as
clockid argument for the conversion period. That means CLOCK_REALTIME is
now captured twice, but that redunancy is only temporary.

As all usage sites of struct system_time_snapshot has to be updated anyway,
rename the 'raw' member to 'monoraw' for clarity.

No functional change vs. current users of ktime_get_snapshot()

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Arthur Kiyanovski <akiyano@amazon.com>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260529195556.971591633@kernel.org
timekeeping: Remove the temporary CLOCK_AUX workaround 2025-07-03T12:44:15+00:00 Thomas Gleixner tglx@linutronix.de 2025-07-03T12:39:28+00:00 8959338617a85e35820e3a7fa21801cf55b068bf ktime_get_clock_ts64() was provided for the networking tree as a stand alone commit based on v6.16-rc1. It contains a temporary workaround for the CLOCK_AUX* defines, which are only available in the timekeeping tree. As this commit is now merged into the timers/ptp branch, which contains the real CLOCK_AUX* defines, the workaround is obsolete. Remove it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/20250701130923.579834908@linutronix.de 
ktime_get_clock_ts64() was provided for the networking tree as a stand
alone commit based on v6.16-rc1. It contains a temporary workaround for the
CLOCK_AUX* defines, which are only available in the timekeeping tree.

As this commit is now merged into the timers/ptp branch, which contains the
real CLOCK_AUX* defines, the workaround is obsolete.

Remove it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250701130923.579834908@linutronix.de
Merge tag 'ktime-get-clock-ts64-for-ptp' into timers/ptp 2025-07-03T12:35:53+00:00 Thomas Gleixner tglx@linutronix.de 2025-07-03T12:35:53+00:00 a6d9638d4da9740c189c141510584161ffd84307 Pull the base implementation of ktime_get_clock_ts64() for PTP, which contains a temporary CLOCK_AUX* workaround. That was created to allow integration of depending changes into the networking tree. The workaround is going to be removed in a subsequent change in the timekeeping tree. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
Pull the base implementation of ktime_get_clock_ts64() for PTP, which
contains a temporary CLOCK_AUX* workaround. That was created to allow
integration of depending changes into the networking tree. The workaround
is going to be removed in a subsequent change in the timekeeping tree.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>