netdev - [PATCH net-next 0/3] Support exposing raw cycle counters in PTP and mlx5

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Message-ID: <1752556533-39218-1-git-send-email-tariqt@nvidia.com>
Date: Tue, 15 Jul 2025 08:15:30 +0300
From: Tariq Toukan <tariqt@...dia.com>
To: Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>, Andrew Lunn <andrew+netdev@...n.ch>, "David
 S. Miller" <davem@...emloft.net>
CC: Saeed Mahameed <saeedm@...dia.com>, Leon Romanovsky <leon@...nel.org>,
	Tariq Toukan <tariqt@...dia.com>, Mark Bloch <mbloch@...dia.com>, "Richard
 Cochran" <richardcochran@...il.com>, <netdev@...r.kernel.org>,
	<linux-rdma@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Carolina Jubran
	<cjubran@...dia.com>
Subject: [PATCH net-next 0/3] Support exposing raw cycle counters in PTP and mlx5

Hi,

This series by Carolina adds support in ptp and usage in mlx5 for
exposing the raw free-running cycle counter of PTP hardware clocks.

Find detailed description by Carolina below [1].

Regards,
Tariq

[1]
This patch series introduces support for exposing the raw free-running
cycle counter of PTP hardware clocks. Some telemetry and low-level
logging use cycle counter timestamps rather than nanoseconds.
Currently, there is no generic interface to correlate these raw values
with system time.

To address this, the series introduces two new ioctl commands that
allow userspace to query the device's raw cycle counter together with
host time:

 - PTP_SYS_OFFSET_PRECISE_CYCLES

 - PTP_SYS_OFFSET_EXTENDED_CYCLES

These commands work like their existing counterparts but return the
device timestamp in cycle units instead of real-time nanoseconds.

This can also be useful in the XDP fast path: if a driver inserts the
raw cycle value into metadata instead of a real-time timestamp, it can
avoid the overhead of converting cycles to time in the kernel. Then
userspace can resolve the cycle-to-time mapping using this ioctl when
needed.

Adds the new PTP ioctls and integrates support in ptp_ioctl():
- ptp: Add ioctl commands to expose raw cycle counter values

Support for exposing raw cycles in mlx5:
- net/mlx5: Extract MTCTR register read logic into helper function
- net/mlx5: Support getcyclesx and getcrosscycles

Carolina Jubran (3):
  ptp: Add ioctl commands to expose raw cycle counter values
  net/mlx5: Extract MTCTR register read logic into helper function
  net/mlx5: Support getcyclesx and getcrosscycles

 .../ethernet/mellanox/mlx5/core/lib/clock.c   | 113 ++++++++++++++++--
 drivers/ptp/ptp_chardev.c                     |  34 ++++--
 include/uapi/linux/ptp_clock.h                |   4 +
 3 files changed, 130 insertions(+), 21 deletions(-)

base-commit: 06baf9bfa6ca8db7d5f32e12e27d1dc1b7cb3a8a
-- 
2.31.1