Add the capability to set parameters through the devlink framework.
The parameter used for controlling PHC (enable/disable) details
are as follows:
- Name: enable_phc
- Type: Boolean (true - enable/false - disable)
- Mode: DEVLINK_PARAM_CMODE_DRIVERINIT
- Effect: Changes take place during driver initialization,
any changes require a devlink reload to take effect.
Signed-off-by: David Arinzon <darinzon@amazon.com>
Link: https://patch.msgid.link/20250617110545.5659-7-darinzon@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Each PHC device kernel registration receives a unique kernel index,
which is associated with a new PHC device file located at
"/dev/ptp<index>".
This device file serves as an interface for obtaining PHC timestamps.
Examples of tools that use "/dev/ptp" include testptp [1]
and chrony [2].
A reset flow may occur in the ENA driver while PHC is active.
During a reset, the driver will unregister and then re-register the
PHC device with the kernel.
Under race conditions, particularly during heavy PHC loads,
the driver’s reset flow might complete faster than the kernel’s PHC
unregister/register process.
This can result in the PHC index being different from what it was prior
to the reset, as the PHC index is selected using kernel ID
allocation [3].
While driver rmmod/insmod are done by the user, a reset may occur
at anytime, without the user awareness, consequently, the driver
might receive a new PHC index after the reset, potentially compromising
the user experience.
To prevent this issue, the PHC flow will detect the reset during PHC
destruction and will skip the PHC unregister/register calls to preserve
the kernel PHC index.
During the reset flow, any attempt to get a PHC timestamp will fail as
expected, but the kernel PHC index will remain unchanged.
[1]: https://github.com/torvalds/linux/blob/v6.1/tools/testing/selftests/ptp/testptp.c
[2]: https://github.com/mlichvar/chrony
[3]: https://www.kernel.org/doc/html/latest/core-api/idr.html
Signed-off-by: Amit Bernstein <amitbern@amazon.com>
Signed-off-by: David Arinzon <darinzon@amazon.com>
Link: https://patch.msgid.link/20250617110545.5659-3-darinzon@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The ENA driver will be extended to support the new PHC feature using
ptp_clock interface [1]. this will provide timestamp reference for user
space to allow measuring time offset between the PHC and the system
clock in order to achieve nanosecond accuracy.
[1] - https://www.kernel.org/doc/html/latest/driver-api/ptp.html
Signed-off-by: Amit Bernstein <amitbern@amazon.com>
Signed-off-by: David Arinzon <darinzon@amazon.com>
Link: https://patch.msgid.link/20250617110545.5659-2-darinzon@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
