[PATCH v2 0/2] ptp: split non-NIC PHC drivers into the clock/timekeeping maintenance domain

[Wen Gu <guwen@linux.alibaba.com>]

Hi all,

This series follows the discussion in RFC [1-2] and v1 [3].


# Background

The PTP Hardware Clock (PHC) interface (/dev/ptpX and the standard PTP_*
ioctls) was originally introduced for IEEE 1588 / network oriented clock
drivers. Over time, it has also become a userspace API for many non-NIC
high-precision clock implementations (virtualization/platform/architecture
provided clocks) [4-8], and more are expected to appear [9-10].

During the review of these incoming non IEEE 1588 based PHC drivers, concerns
were raised that such "non-NIC" clocks may not be a good fit for the netdev
maintainership model [11], where PTP/PHC drivers are currently maintained.
This leaves an unclear upstream home and maintainership model for this class
of drivers.


# Proposal

This series proposes moving PHC drivers that expose a high-precision clock to
userspace via the existing PTP interface but are not tied to the traditional
NIC/IEEE 1588 packet timestamping pipeline, out of the netdev maintenance
domain and into the clock/timekeeping maintenance domain.

As discussed in [3], this series makes the separation explicit by reorganizing
the drivers/ptp/ layout into the following groups. This provides clearer
ownership and long-term maintenance boundaries:

  - drivers/ptp/          : PTP core infrastructure and
                            network / IEEE 1588 oriented PTP drivers.

  - drivers/ptp/emulated/ : emulated/virtual PTP drivers. They are typically
                            platform/architecture/virtualization/special
                            hardware provided high-precision time sources.

Patch 1 performs the refactor: move drivers and split Kconfig/Makefiles
accordingly, without intended functional changes.

Patch 2 updates MAINTAINERS to match the new layout and adds a dedicated entry
for drivers/ptp/emulated/, moving review and ownership routing for this class
of drivers away from the netdev maintainership.

No userspace ABI changes are intended; this is a refactor and maintenance
metadata update only.


# Changes since Patch v1:

- List David Woodhouse as the maintainer of emulated PTP drivers.

- Adjust the directory layout: instead of creating both ieee1588/ and
  emulated/ subdirectories, keep the network-oriented drivers in the
  main drivers/ptp/ directory and only split out the emulated drivers.


# Changes since RFC v2:

- Keep ptp_ocp under the IEEE1588/network-oriented PTP drivers as suggested
  by Jakub.

- Following the model used by NTP related code, this series lists tip.git
  (timers/core) as the integration tree for emulated PTP clocks in the
  MAINTAINERS entry. Guidance from clock/timekeeping maintainers
  (Thomas Gleixner, John Stultz, Anna-Maria Behnsen, Frederic Weisbecker,
  Daniel Lezcano, Stephen Boyd) on whether this is the appropriate workflow
  for this class of drivers would be appreciated.

- Continue listing ourselves as maintainers for now as a fallback contact
  point. In the long term it would be preferable for this area to be
  maintained by clock/timekeeping experts, and suggestions are welcome.


Thanks for any input.

Regards.

[1] https://lore.kernel.org/all/0afe19db-9c7f-4228-9fc2-f7b34c4bc227@linux.alibaba.com/
[2] https://lore.kernel.org/all/20260227081934.96865-1-guwen@linux.alibaba.com/
[3] https://lore.kernel.org/all/20260318073330.115808-1-guwen@linux.alibaba.com/
[4] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a0e136d436ded817c0aade72efdefa56a00b4e5e
[5] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7d10001e20e46ad6ad95622164686bc2cbfc9802
[6] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2d7de7a3010d713fb89b7ba99e6fdc14475ad106
[7] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3716a49a81ba19dda7202633a68b28564ba95eb5
[8] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9a17125a18f9ae1e1233a8e2d919059445b9d6fd
[9] https://lore.kernel.org/netdev/20251030121314.56729-1-guwen@linux.alibaba.com/
[10] https://lore.kernel.org/mhi/20250818-tsc_time_sync-v1-0-2747710693ba@oss.qualcomm.com/
[11] https://lore.kernel.org/netdev/20251127083610.6b66a728@kernel.org/

Wen Gu (2):
  ptp: move emulated/virtual clock drivers into a dedicated subdirectory
  MAINTAINERS: update PTP maintainer entries after directory split

 MAINTAINERS                                 | 21 +++++--
 drivers/ptp/Kconfig                         | 68 ++++-----------------
 drivers/ptp/Makefile                        | 11 ++--
 drivers/ptp/emulated/Kconfig                | 61 ++++++++++++++++++
 drivers/ptp/emulated/Makefile               | 11 ++++
 drivers/ptp/{ => emulated}/ptp_kvm_arm.c    |  0
 drivers/ptp/{ => emulated}/ptp_kvm_common.c |  0
 drivers/ptp/{ => emulated}/ptp_kvm_x86.c    |  0
 drivers/ptp/{ => emulated}/ptp_s390.c       |  0
 drivers/ptp/{ => emulated}/ptp_vmclock.c    |  0
 drivers/ptp/{ => emulated}/ptp_vmw.c        |  0
 11 files changed, 103 insertions(+), 69 deletions(-)
 create mode 100644 drivers/ptp/emulated/Kconfig
 create mode 100644 drivers/ptp/emulated/Makefile
 rename drivers/ptp/{ => emulated}/ptp_kvm_arm.c (100%)
 rename drivers/ptp/{ => emulated}/ptp_kvm_common.c (100%)
 rename drivers/ptp/{ => emulated}/ptp_kvm_x86.c (100%)
 rename drivers/ptp/{ => emulated}/ptp_s390.c (100%)
 rename drivers/ptp/{ => emulated}/ptp_vmclock.c (100%)
 rename drivers/ptp/{ => emulated}/ptp_vmw.c (100%)

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2.43.5