1.. SPDX-License-Identifier: GPL-2.0 2.. include:: <isonum.txt> 3 4=============================== 5DPAA2 Ethernet driver 6=============================== 7 8:Copyright: |copy| 2017-2018 NXP 9 10This file provides documentation for the Freescale DPAA2 Ethernet driver. 11 12Supported Platforms 13=================== 14This driver provides networking support for Freescale DPAA2 SoCs, e.g. 15LS2080A, LS2088A, LS1088A. 16 17 18Architecture Overview 19===================== 20Unlike regular NICs, in the DPAA2 architecture there is no single hardware block 21representing network interfaces; instead, several separate hardware resources 22concur to provide the networking functionality: 23 24- network interfaces 25- queues, channels 26- buffer pools 27- MAC/PHY 28 29All hardware resources are allocated and configured through the Management 30Complex (MC) portals. MC abstracts most of these resources as DPAA2 objects 31and exposes ABIs through which they can be configured and controlled. A few 32hardware resources, like queues, do not have a corresponding MC object and 33are treated as internal resources of other objects. 34 35For a more detailed description of the DPAA2 architecture and its object 36abstractions see 37*Documentation/networking/device_drivers/ethernet/freescale/dpaa2/overview.rst*. 38 39Each Linux net device is built on top of a Datapath Network Interface (DPNI) 40object and uses Buffer Pools (DPBPs), I/O Portals (DPIOs) and Concentrators 41(DPCONs). 42 43Configuration interface:: 44 45 ----------------------- 46 | DPAA2 Ethernet Driver | 47 ----------------------- 48 . . . 49 . . . 50 . . . . . . . . . . . . 51 . . . 52 . . . 53 ---------- ---------- ----------- 54 | DPBP API | | DPNI API | | DPCON API | 55 ---------- ---------- ----------- 56 . . . software 57 ======= . ========== . ============ . =================== 58 . . . hardware 59 ------------------------------------------ 60 | MC hardware portals | 61 ------------------------------------------ 62 . . . 63 . . . 64 ------ ------ ------- 65 | DPBP | | DPNI | | DPCON | 66 ------ ------ ------- 67 68The DPNIs are network interfaces without a direct one-on-one mapping to PHYs. 69DPBPs represent hardware buffer pools. Packet I/O is performed in the context 70of DPCON objects, using DPIO portals for managing and communicating with the 71hardware resources. 72 73Datapath (I/O) interface:: 74 75 ----------------------------------------------- 76 | DPAA2 Ethernet Driver | 77 ----------------------------------------------- 78 | ^ ^ | | 79 | | | | | 80 enqueue| dequeue| data | dequeue| seed | 81 (Tx) | (Rx, TxC)| avail.| request| buffers| 82 | | notify| | | 83 | | | | | 84 V | | V V 85 ----------------------------------------------- 86 | DPIO Driver | 87 ----------------------------------------------- 88 | | | | | software 89 | | | | | ================ 90 | | | | | hardware 91 ----------------------------------------------- 92 | I/O hardware portals | 93 ----------------------------------------------- 94 | ^ ^ | | 95 | | | | | 96 | | | V | 97 V | ================ V 98 ---------------------- | ------------- 99 queues ---------------------- | | Buffer pool | 100 ---------------------- | ------------- 101 ======================= 102 Channel 103 104Datapath I/O (DPIO) portals provide enqueue and dequeue services, data 105availability notifications and buffer pool management. DPIOs are shared between 106all DPAA2 objects (and implicitly all DPAA2 kernel drivers) that work with data 107frames, but must be affine to the CPUs for the purpose of traffic distribution. 108 109Frames are transmitted and received through hardware frame queues, which can be 110grouped in channels for the purpose of hardware scheduling. The Ethernet driver 111enqueues TX frames on egress queues and after transmission is complete a TX 112confirmation frame is sent back to the CPU. 113 114When frames are available on ingress queues, a data availability notification 115is sent to the CPU; notifications are raised per channel, so even if multiple 116queues in the same channel have available frames, only one notification is sent. 117After a channel fires a notification, is must be explicitly rearmed. 118 119Each network interface can have multiple Rx, Tx and confirmation queues affined 120to CPUs, and one channel (DPCON) for each CPU that services at least one queue. 121DPCONs are used to distribute ingress traffic to different CPUs via the cores' 122affine DPIOs. 123 124The role of hardware buffer pools is storage of ingress frame data. Each network 125interface has a privately owned buffer pool which it seeds with kernel allocated 126buffers. 127 128 129DPNIs are decoupled from PHYs; a DPNI can be connected to a PHY through a DPMAC 130object or to another DPNI through an internal link, but the connection is 131managed by MC and completely transparent to the Ethernet driver. 132 133:: 134 135 --------- --------- --------- 136 | eth if1 | | eth if2 | | eth ifn | 137 --------- --------- --------- 138 . . . 139 . . . 140 . . . 141 --------------------------- 142 | DPAA2 Ethernet Driver | 143 --------------------------- 144 . . . 145 . . . 146 . . . 147 ------ ------ ------ ------- 148 | DPNI | | DPNI | | DPNI | | DPMAC |----+ 149 ------ ------ ------ ------- | 150 | | | | | 151 | | | | ----- 152 =========== ================== | PHY | 153 ----- 154 155Creating a Network Interface 156============================ 157A net device is created for each DPNI object probed on the MC bus. Each DPNI has 158a number of properties which determine the network interface configuration 159options and associated hardware resources. 160 161DPNI objects (and the other DPAA2 objects needed for a network interface) can be 162added to a container on the MC bus in one of two ways: statically, through a 163Datapath Layout Binary file (DPL) that is parsed by MC at boot time; or created 164dynamically at runtime, via the DPAA2 objects APIs. 165 166 167Features & Offloads 168=================== 169Hardware checksum offloading is supported for TCP and UDP over IPv4/6 frames. 170The checksum offloads can be independently configured on RX and TX through 171ethtool. 172 173Hardware offload of unicast and multicast MAC filtering is supported on the 174ingress path and permanently enabled. 175 176Scatter-gather frames are supported on both RX and TX paths. On TX, SG support 177is configurable via ethtool; on RX it is always enabled. 178 179The DPAA2 hardware can process jumbo Ethernet frames of up to 10K bytes. 180 181The Ethernet driver defines a static flow hashing scheme that distributes 182traffic based on a 5-tuple key: src IP, dst IP, IP proto, L4 src port, 183L4 dst port. No user configuration is supported for now. 184 185Hardware specific statistics for the network interface as well as some 186non-standard driver stats can be consulted through ethtool -S option. 187