mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-03 09:41:54 +09:00
08ef8bc825
The SIOCSHWTSTAMP ioctl configures HW timestamping on a given port. In Spectrum-2 and above, each packet gets time stamp by default, but in order to provide an accurate time stamp, software should configure to update the correction field. In addition, the PTP traps are not enabled by default, software should enable it per port or for all ports. The switch behaves like a transparent clock between CPU port and each front panel port. If ingress correction is set on a port for a given packet type, then when such a packet is received via the port, the current time stamp is subtracted from the correction field. If egress correction is set on a port for a given packet type, then when such a packet is transmitted via the port, the current time stamp is added to the correction field. The result is that as the packet ingresses through a port with ingress correction enabled, and egresses through a port with egress correction enabled, the PTP correction field is updated to reflect the time that the packet spent in the ASIC. This can be used to update the correction field of trapped packets by enabling ingress correction on a port where time stamping was enabled, and egress correction on the CPU port. Similarly, for packets transmitted from the host, ingress correction should be enabled on the CPU port, and egress correction on a front-panel port. However, since the correction fields will be updated for all PTP packets crossing the CPU port, in order not to mangle the correction field, the front panel port involved in the packet transfer must have the corresponding correction enabled as well. Therefore, when HW timestamping is enabled on at least one port, we have to configure hardware to update the correction field and trap PTP event packets on all ports. Add reference count as part of 'struct mlxsw_sp_ptp_state', to maintain how many ports use HW timestamping. Handle the correction field configuration only when the first port enables time stamping and when the last port disables time stamping. Store the configuration as part of 'struct mlxsw_sp_ptp_state', as it is global for all ports. The SIOCGHWTSTAMP ioctl is a getter for the current configuration, implement it and use the global configuration. Signed-off-by: Danielle Ratson <danieller@nvidia.com> Signed-off-by: Amit Cohen <amcohen@nvidia.com> Reviewed-by: Petr Machata <petrm@nvidia.com> Signed-off-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.