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Diffstat (limited to 'Documentation/networking/device_drivers/ethernet/marvell')
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diff --git a/Documentation/networking/device_drivers/ethernet/marvell/octeontx2.rst b/Documentation/networking/device_drivers/ethernet/marvell/octeontx2.rst new file mode 100644 index 000000000..88f508338 --- /dev/null +++ b/Documentation/networking/device_drivers/ethernet/marvell/octeontx2.rst @@ -0,0 +1,159 @@ +.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) + +==================================== +Marvell OcteonTx2 RVU Kernel Drivers +==================================== + +Copyright (c) 2020 Marvell International Ltd. + +Contents +======== + +- `Overview`_ +- `Drivers`_ +- `Basic packet flow`_ + +Overview +======== + +Resource virtualization unit (RVU) on Marvell's OcteonTX2 SOC maps HW +resources from the network, crypto and other functional blocks into +PCI-compatible physical and virtual functions. Each functional block +again has multiple local functions (LFs) for provisioning to PCI devices. +RVU supports multiple PCIe SRIOV physical functions (PFs) and virtual +functions (VFs). PF0 is called the administrative / admin function (AF) +and has privileges to provision RVU functional block's LFs to each of the +PF/VF. + +RVU managed networking functional blocks + - Network pool or buffer allocator (NPA) + - Network interface controller (NIX) + - Network parser CAM (NPC) + - Schedule/Synchronize/Order unit (SSO) + - Loopback interface (LBK) + +RVU managed non-networking functional blocks + - Crypto accelerator (CPT) + - Scheduled timers unit (TIM) + - Schedule/Synchronize/Order unit (SSO) + Used for both networking and non networking usecases + +Resource provisioning examples + - A PF/VF with NIX-LF & NPA-LF resources works as a pure network device + - A PF/VF with CPT-LF resource works as a pure crypto offload device. + +RVU functional blocks are highly configurable as per software requirements. + +Firmware setups following stuff before kernel boots + - Enables required number of RVU PFs based on number of physical links. + - Number of VFs per PF are either static or configurable at compile time. + Based on config, firmware assigns VFs to each of the PFs. + - Also assigns MSIX vectors to each of PF and VFs. + - These are not changed after kernel boot. + +Drivers +======= + +Linux kernel will have multiple drivers registering to different PF and VFs +of RVU. Wrt networking there will be 3 flavours of drivers. + +Admin Function driver +--------------------- + +As mentioned above RVU PF0 is called the admin function (AF), this driver +supports resource provisioning and configuration of functional blocks. +Doesn't handle any I/O. It sets up few basic stuff but most of the +funcionality is achieved via configuration requests from PFs and VFs. + +PF/VFs communicates with AF via a shared memory region (mailbox). Upon +receiving requests AF does resource provisioning and other HW configuration. +AF is always attached to host kernel, but PFs and their VFs may be used by host +kernel itself, or attached to VMs or to userspace applications like +DPDK etc. So AF has to handle provisioning/configuration requests sent +by any device from any domain. + +AF driver also interacts with underlying firmware to + - Manage physical ethernet links ie CGX LMACs. + - Retrieve information like speed, duplex, autoneg etc + - Retrieve PHY EEPROM and stats. + - Configure FEC, PAM modes + - etc + +From pure networking side AF driver supports following functionality. + - Map a physical link to a RVU PF to which a netdev is registered. + - Attach NIX and NPA block LFs to RVU PF/VF which provide buffer pools, RQs, SQs + for regular networking functionality. + - Flow control (pause frames) enable/disable/config. + - HW PTP timestamping related config. + - NPC parser profile config, basically how to parse pkt and what info to extract. + - NPC extract profile config, what to extract from the pkt to match data in MCAM entries. + - Manage NPC MCAM entries, upon request can frame and install requested packet forwarding rules. + - Defines receive side scaling (RSS) algorithms. + - Defines segmentation offload algorithms (eg TSO) + - VLAN stripping, capture and insertion config. + - SSO and TIM blocks config which provide packet scheduling support. + - Debugfs support, to check current resource provising, current status of + NPA pools, NIX RQ, SQ and CQs, various stats etc which helps in debugging issues. + - And many more. + +Physical Function driver +------------------------ + +This RVU PF handles IO, is mapped to a physical ethernet link and this +driver registers a netdev. This supports SR-IOV. As said above this driver +communicates with AF with a mailbox. To retrieve information from physical +links this driver talks to AF and AF gets that info from firmware and responds +back ie cannot talk to firmware directly. + +Supports ethtool for configuring links, RSS, queue count, queue size, +flow control, ntuple filters, dump PHY EEPROM, config FEC etc. + +Virtual Function driver +----------------------- + +There are two types VFs, VFs that share the physical link with their parent +SR-IOV PF and the VFs which work in pairs using internal HW loopback channels (LBK). + +Type1: + - These VFs and their parent PF share a physical link and used for outside communication. + - VFs cannot communicate with AF directly, they send mbox message to PF and PF + forwards that to AF. AF after processing, responds back to PF and PF forwards + the reply to VF. + - From functionality point of view there is no difference between PF and VF as same type + HW resources are attached to both. But user would be able to configure few stuff only + from PF as PF is treated as owner/admin of the link. + +Type2: + - RVU PF0 ie admin function creates these VFs and maps them to loopback block's channels. + - A set of two VFs (VF0 & VF1, VF2 & VF3 .. so on) works as a pair ie pkts sent out of + VF0 will be received by VF1 and viceversa. + - These VFs can be used by applications or virtual machines to communicate between them + without sending traffic outside. There is no switch present in HW, hence the support + for loopback VFs. + - These communicate directly with AF (PF0) via mbox. + +Except for the IO channels or links used for packet reception and transmission there is +no other difference between these VF types. AF driver takes care of IO channel mapping, +hence same VF driver works for both types of devices. + +Basic packet flow +================= + +Ingress +------- + +1. CGX LMAC receives packet. +2. Forwards the packet to the NIX block. +3. Then submitted to NPC block for parsing and then MCAM lookup to get the destination RVU device. +4. NIX LF attached to the destination RVU device allocates a buffer from RQ mapped buffer pool of NPA block LF. +5. RQ may be selected by RSS or by configuring MCAM rule with a RQ number. +6. Packet is DMA'ed and driver is notified. + +Egress +------ + +1. Driver prepares a send descriptor and submits to SQ for transmission. +2. The SQ is already configured (by AF) to transmit on a specific link/channel. +3. The SQ descriptor ring is maintained in buffers allocated from SQ mapped pool of NPA block LF. +4. NIX block transmits the pkt on the designated channel. +5. NPC MCAM entries can be installed to divert pkt onto a different channel. |