timekeeping/ptp: Expand snapshot functionality [LWN.net]

From:		Thomas Gleixner <tglx-AT-kernel.org>
To:		LKML <linux-kernel-AT-vger.kernel.org>
Subject:		[patch 00/24] timekeeping/ptp: Expand snapshot functionality
Date:		Tue, 26 May 2026 19:13:28 +0200
Message-ID:		<20260526165826.392227559@kernel.org>
Cc:		David Woodhouse <dwmw2-AT-infradead.org>, Miroslav Lichvar <mlichvar-AT-redhat.com>, John Stultz <jstultz-AT-google.com>, Stephen Boyd <sboyd-AT-kernel.org>, Anna-Maria Behnsen <anna-maria-AT-linutronix.de>, Frederic Weisbecker <frederic-AT-kernel.org>, thomas.weissschuh-AT-linutronix.de, Arthur Kiyanovski <akiyano-AT-amazon.com>, Rodolfo Giometti <giometti-AT-enneenne.com>, Vincent Donnefort <vdonnefort-AT-google.com>, Marc Zyngier <maz-AT-kernel.org>, Oliver Upton <oliver.upton-AT-linux.dev>, kvmarm-AT-lists.linux.dev, Oliver Upton <oupton-AT-kernel.org>, Richard Cochran <richardcochran-AT-gmail.com>, netdev-AT-vger.kernel.org, Takashi Iwai <tiwai-AT-suse.com>, Miri Korenblit <miriam.rachel.korenblit-AT-intel.com>, Johannes Berg <johannes.berg-AT-intel.com>, Jacob Keller <jacob.e.keller-AT-intel.com>, Tony Nguyen <anthony.l.nguyen-AT-intel.com>, Saeed Mahameed <saeedm-AT-nvidia.com>, Peter Hilber <peter.hilber-AT-oss.qualcomm.com>, "Michael S. Tsirkin" <mst-AT-redhat.com>, virtualization-AT-lists.linux.dev, linux-wireless-AT-vger.kernel.org, linux-sound-AT-vger.kernel.org
Archive-link:		Article

Sorry for the large CC list, but changing the inner workings touches
unfortunately a lot of places in one go.

PTP wants to grow new snapshot functionality, which provides not only the
captured CLOCK* values, but also the underlying clocksource counter value.

   https://lore.kernel.org/20260515164033.6403-1-akiyano@ama...

There was quite some discussion in seemingly related threads how to capture
these values and how to provide core infrastructure so that driver writers
have something to work with

   https://lore.kernel.org/20260514225842.110706-1-hramamurt...
   https://lore.kernel.org/20260520135207.37826-1-dwmw2@infr...

This series implements the timekeeping related mechanisms to:

     1) Capture CLOCK values along with the clocksource counter value for
     	non-hardware based sampling

     2) Expanding the hardware cross time stamp mechanism to hand back the
     	clocksource counter value, which was captured by the device, along
     	with the related CLOCK values

     3) Adding AUX clock support to the hardware cross timestamping core

It's based on v7.1-rc2 and also available from git:

    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git timekeeping-ptp-extend-v1

Thanks to David for rebasing his PTP/timekeeping work on top and providing
feedback, fixes and testing.

Thanks,

	tglx
---
 arch/arm64/kvm/hyp_trace.c                          |    8 
 arch/arm64/kvm/hypercalls.c                         |    6 
 drivers/net/dsa/sja1105/sja1105_main.c              |    8 
 drivers/net/ethernet/intel/ice/ice_ptp.c            |    5 
 drivers/net/ethernet/intel/igc/igc.h                |    1 
 drivers/net/ethernet/intel/igc/igc_ptp.c            |    4 
 drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c |    4 
 drivers/net/wireless/intel/iwlwifi/mld/ptp.c        |    5 
 drivers/net/wireless/intel/iwlwifi/mvm/ptp.c        |    7 
 drivers/pps/generators/pps_gen-dummy.c              |    6 
 drivers/pps/generators/pps_gen_tio.c                |    6 
 drivers/ptp/ptp_chardev.c                           |   18 +
 drivers/ptp/ptp_ocp.c                               |   11 -
 drivers/ptp/ptp_vmclock.c                           |   25 --
 drivers/virtio/virtio_rtc_ptp.c                     |    2 
 include/linux/pps_kernel.h                          |    8 
 include/linux/ptp_clock_kernel.h                    |   15 -
 include/linux/timekeeping.h                         |   54 ++---
 kernel/time/timekeeping.c                           |  211 ++++++++++++--------
 sound/hda/common/controller.c                       |    4 
 20 files changed, 236 insertions(+), 172 deletions(-)