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[5.12.16.165]) by smtp.gmail.com with ESMTPSA id y12sm9294825ejb.104.2021.03.16.04.24.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 16 Mar 2021 04:24:36 -0700 (PDT) From: Vladimir Oltean To: netdev@vger.kernel.org Cc: Andrew Lunn , Florian Fainelli , Vivien Didelot , Jiri Pirko , Ido Schimmel , Tobias Waldekranz , Vladimir Oltean , George McCollister Subject: [PATCH v2 net-next 10/12] Documentation: networking: dsa: add paragraph for the HSR/PRP offload Date: Tue, 16 Mar 2021 13:24:17 +0200 Message-Id: <20210316112419.1304230-11-olteanv@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210316112419.1304230-1-olteanv@gmail.com> References: <20210316112419.1304230-1-olteanv@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Vladimir Oltean Add a short summary of the methods that a driver writer must implement for offloading a HSR/PRP network interface. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Reviewed-by: George McCollister --- 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 0daafa2fb9eb..69040e11ee5e 100644 --- a/Documentation/networking/dsa/dsa.rst +++ b/Documentation/networking/dsa/dsa.rst @@ -787,6 +787,38 @@ 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 discovery of 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 are not implemented (therefore, bridging a hsr network +interface with a physical switch port does not produce the expected result). + +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 ====