Hi all,

This series follows the discussion in RFC [1-2], v1 [3] and v2 [4].


# Background

The PTP Hardware Clock (PHC) interface (/dev/ptpX and the standard PTP_*
ioctls) is used by two distinct classes of drivers in drivers/ptp/:
host-disciplined PHC drivers whose frequency and phase are adjusted by
the host's time synchronization stack, and non-host-disciplined PHC
drivers that expose an external precision time reference and are
read-only. Several non-host-disciplined PHC drivers already exist in
the kernel [5-9], and more are expected to appear [10-11].

During review of incoming non-host-disciplined PHC drivers, concerns
were raised that they may not be a good fit for the netdev maintainership
model [12], where all PTP/PHC drivers are currently maintained. This
leaves an unclear upstream home and maintainership model for this class
of drivers.


# Proposal

This series makes the separation explicit by reorganizing the drivers/ptp/
layout into the following groups:

  - drivers/ptp/          : PTP core infrastructure and host-disciplined
                            PHC drivers.

  - drivers/ptp/emulated/ : non-host-disciplined PHC drivers that expose
                            precision time from hypervisors, platforms,
                            or firmware. These clocks are read-only and
                            not adjusted by the host.

Patch 1 performs the directory reorganization: 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/.

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


# Changes since v2:

- List David Woodhouse as the sole maintainer (M:) of emulated PTP
  drivers as suggested by Jakub. Wen Gu and Xuan Zhuo are listed as
  reviewers (R:).

- Updated the T: field to use David's tree:
  git://git.infradead.org/linux-ptp.git

- Reworded commit messages to clarify the distinction between the two
  groups as host-disciplined vs. read-only (devices that purport to know
  real time better than the host).


# Changes since 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 network-oriented PTP drivers as suggested
  by Jakub.


Thanks for any input.

Regards.

[1] https://lore.kernel.org/all/0afe19db-9c7f-4228-9fc2-f7b34c4bc227@linux.alibaba.com/ (local)
[2] https://lore.kernel.org/all/20260227081934.96865-1-guwen@linux.alibaba.com/ (local)
[3] https://lore.kernel.org/all/20260318073330.115808-1-guwen@linux.alibaba.com/ (local)
[4] https://lore.kernel.org/all/20260407104802.34429-1-guwen@linux.alibaba.com/ (local)
[5] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a0e136d436ded817c0aade72efdefa56a00b4e5e
[6] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7d10001e20e46ad6ad95622164686bc2cbfc9802
[7] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2d7de7a3010d713fb89b7ba99e6fdc14475ad106
[8] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3716a49a81ba19dda7202633a68b28564ba95eb5
[9] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9a17125a18f9ae1e1233a8e2d919059445b9d6fd
[10] https://lore.kernel.org/netdev/20251030121314.56729-1-guwen@linux.alibaba.com/ (local)
[11] https://lore.kernel.org/mhi/20250818-tsc_time_sync-v1-0-2747710693ba@oss.qualcomm.com/ (local)
[12] https://lore.kernel.org/netdev/20251127083610.6b66a728@kernel.org/ (local)

Wen Gu (2):
  ptp: move non-host-disciplined clock drivers into a dedicated
    subdirectory
  MAINTAINERS: update PTP maintainer entries after directory split

 MAINTAINERS                                 | 21 +++++--
 drivers/ptp/Kconfig                         | 55 +------------------
 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, 94 insertions(+), 65 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