From: Vladimir Oltean <vladimir.olt...@nxp.com> Add a short summary of the methods that a driver writer must implement for offloading a HSR/PRP network interface.
Cc: George McCollister <george.mccollis...@gmail.com> Signed-off-by: Vladimir Oltean <vladimir.olt...@nxp.com> --- Documentation/networking/dsa/dsa.rst | 32 ++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/Documentation/networking/dsa/dsa.rst b/Documentation/networking/dsa/dsa.rst index bf82f2aed29a..277045346f3a 100644 --- a/Documentation/networking/dsa/dsa.rst +++ b/Documentation/networking/dsa/dsa.rst @@ -760,6 +760,38 @@ to work properly. The operations are detailed below. which MRP PDUs should be trapped to software and which should be autonomously forwarded. +IEC 62439-3 (HSR/PRP) +--------------------- + +The Parallel Redundancy Protocol (PRP) is a network redundancy protocol which +works by duplicating and sequence numbering packets through two independent L2 +networks (which are unaware of the PRP tail tags carried in the packets), and +eliminating the duplicates at the receiver. The High-availability Seamless +Redundancy (HSR) protocol is similar in concept, except all nodes that carry +the redundant traffic are aware of the fact that it is HSR-tagged (because HSR +uses a header with an EtherType of 0x892f) and are physically connected in a +ring topology. Both HSR and PRP use supervision frames for monitoring the +health of the network and for discovering the other nodes. + +In Linux, both HSR and PRP are implemented in the hsr driver, which +instantiates a virtual, stackable network interface with two member ports. +The driver only implements the basic roles of DANH (Doubly Attached Node +implementing HSR) and DANP (Doubly Attached Node implementing PRP); the roles +of RedBox and QuadBox aren't (therefore, bridging a hsr network interface with +a physical switch port is not supported). + +A driver which is able of offloading certain functions of a DANP or DANH should +declare the corresponding netdev features as indicated by the documentation at +``Documentation/networking/netdev-features.rst``. Additionally, the following +methods must be implemented: + +- ``port_hsr_join``: function invoked when a given switch port is added to a + DANP/DANH. The driver may return ``-EOPNOTSUPP`` and in this case, DSA will + fall back to a software implementation where all traffic from this port is + sent to the CPU. +- ``port_hsr_leave``: function invoked when a given switch port leaves a + DANP/DANH and returns to normal operation as a standalone port. + TODO ==== -- 2.25.1
