Lines Matching +full:ethernet +full:- +full:switch
1 Distributed Switch Architecture
7 This document describes the Distributed Switch Architecture (DSA) subsystem
15 The Distributed Switch Architecture is a subsystem which was primarily designed
16 to support Marvell Ethernet switches (MV88E6xxx, a.k.a Linkstreet product line)
21 they configured/queried a switch port network device or a regular network
24 An Ethernet switch is typically comprised of multiple front-panel ports, and one
26 presence of a management port connected to an Ethernet controller capable of
27 receiving Ethernet frames from the switch. This is a very common setup for all
28 kinds of Ethernet switches found in Small Home and Office products: routers,
29 gateways, or even top-of-the rack switches. This host Ethernet controller will
34 using upstream and downstream Ethernet links between switches. These specific
36 of multiple switches connected to each other is called a "switch tree".
38 For each front-panel port, DSA will create specialized network devices which are
39 used as controlling and data-flowing endpoints for use by the Linux networking
43 The ideal case for using DSA is when an Ethernet switch supports a "switch tag"
44 which is a hardware feature making the switch insert a specific tag for each
45 Ethernet frames it received to/from specific ports to help the management
48 - what port is this frame coming from
49 - what was the reason why this frame got forwarded
50 - how to send CPU originated traffic to specific ports
54 on Port-based VLAN IDs).
59 - the "cpu" port is the Ethernet switch facing side of the management
63 - the "dsa" port(s) are just conduits between two or more switches, and as such
65 downstream, or the top-most upstream interface makes sense with that model
67 Switch tagging protocols
68 ------------------------
70 DSA currently supports 5 different tagging protocols, and a tag-less mode as
82 - identifies which port the Ethernet frame came from/should be sent to
83 - provides a reason why this frame was forwarded to the management interface
86 ----------------------
89 the CPU/management Ethernet interface. Such a driver might occasionally need to
95 Ethernet switch.
98 ----------------------
101 networking stack is in order to have the DSA subsystem process the Ethernet
102 switch specific tagging protocol. DSA accomplishes this by registering a
103 specific (and fake) Ethernet type (later becoming skb->protocol) with the
105 Ethernet Frame receive sequence looks like this:
110 - receive function is invoked
111 - basic packet processing is done: getting length, status etc.
112 - packet is prepared to be processed by the Ethernet layer by calling
115 net/ethernet/eth.c:
118 if (dev->dsa_ptr != NULL)
119 -> skb->protocol = ETH_P_XDSA
121 drivers/net/ethernet/*:
124 -> iterate over registered packet_type
125 -> invoke handler for ETH_P_XDSA, calls dsa_switch_rcv()
128 -> dsa_switch_rcv()
129 -> invoke switch tag specific protocol handler in
133 -> inspect and strip switch tag protocol to determine originating port
134 -> locate per-port network device
135 -> invoke eth_type_trans() with the DSA slave network device
136 -> invoked netif_receive_skb()
138 Past this point, the DSA slave network devices get delivered regular Ethernet
142 ---------------------
146 controlling and data-flowing end-point for each front-panel port of the switch.
149 - insert/remove the switch tag protocol (if it exists) when sending traffic
150 to/from specific switch ports
151 - query the switch for ethtool operations: statistics, link state,
152 Wake-on-LAN, register dumps...
153 - external/internal PHY management: link, auto-negotiation etc.
157 stack/ethtool, and the switch driver implementation.
160 switch tagging protocol is currently registered with these network devices, and
162 switch tag in the Ethernet frames.
165 ndo_start_xmit() function, since they contain the appropriate switch tag, the
166 Ethernet switch will be able to process these incoming frames from the
167 management interface and delivers these frames to the physical switch port.
170 ------------------------
176 |---------------------------
178 ----------------------------
179 | <tag added by switch |
183 |--------------------------------------------|
184 | Switch driver |
185 |--------------------------------------------|
187 |-------| |-------| |-------|
189 |-------| |-------| |-------|
192 --------------
194 In order to be able to read to/from a switch PHY built into it, DSA creates a
195 slave MDIO bus which allows a specific switch driver to divert and intercept
196 MDIO reads/writes towards specific PHY addresses. In most MDIO-connected
198 to return standard MII registers from the switch builtin PHYs, allowing the PHY
199 library and/or to return link status, link partner pages, auto-negotiation
202 For Ethernet switches which have both external and internal MDIO busses, the
204 internal or external MDIO devices this switch might be connected to: internal
208 ---------------
213 dsa_chip_data: platform data configuration for a given switch device, this
214 structure describes a switch device's parent device, its address, as well as
220 master network device this switch tree is attached to needs to be referenced
224 the tagging protocol supported by the switch tree, and which receive/transmit
225 function hooks should be invoked, information about the directly attached switch
229 dsa_switch: structure describing a switch device in the tree, referencing a
240 -------------------------------
243 it will register the entire DSA switch tree attached to a master network device
244 in one-shot, facilitating the device creation and simplifying the device driver
247 - building DSA and its switch drivers as modules is currently not working
248 - the device driver parenting does not necessarily reflect the original
249 bus/device the switch can be created from
250 - supporting non-MDIO and non-MMIO (platform) switches is not possible
253 -----------------------------------------
256 (DSA_MAX_SWITCHES), and the number of ports per switch to 12 (DSA_MAX_PORTS).
261 -------------------------------
266 - inability to fetch switch CPU port statistics counters using ethtool, which
267 can make it harder to debug MDIO switch connected using xMII interfaces
269 - inability to configure the CPU port link parameters based on the Ethernet
272 - inability to configure specific VLAN IDs / trunking VLANs between switches
276 --------------------------------
278 Once a master network device is configured to use DSA (dev->dsa_ptr becomes
279 non-NULL), and the switch behind it expects a tagging protocol, this network
282 will not make us go through the switch tagging protocol transmit function, so
283 the Ethernet switch on the other end, expecting a tag will typically drop this
295 - MDIO/PHY library: drivers/net/phy/phy.c, mdio_bus.c
296 - Switchdev: net/switchdev/*
297 - Device Tree for various of_* functions
300 ----------------
306 - internal PHY devices, built into the Ethernet switch hardware
307 - external PHY devices, connected via an internal or external MDIO bus
308 - internal PHY devices, connected via an internal MDIO bus
309 - special, non-autonegotiated or non MDIO-managed PHY devices: SFPs, MoCA; a.k.a
315 - if Device Tree is used, the PHY device is looked up using the standard
316 "phy-handle" property, if found, this PHY device is created and registered
319 - if Device Tree is used, and the PHY device is "fixed", that is, conforms to
320 the definition of a non-MDIO managed PHY as defined in
321 Documentation/devicetree/bindings/net/fixed-link.txt, the PHY is registered
324 - finally, if the PHY is built into the switch, as is very common with
325 standalone switch packages, the PHY is probed using the slave MII bus created
330 ---------
334 of per-port slave network devices. Since DSA primarily deals with
335 MDIO-connected switches, although not exclusively, SWITCHDEV's
337 checks whether the operation is supported by the DSA switch driver, and a commit
344 -----------
349 per-port PHY specific details: interface connection, MDIO bus location etc..
354 DSA switch drivers need to implement a dsa_switch_ops structure which will
363 Switch configuration
364 --------------------
366 - tag_protocol: this is to indicate what kind of tagging protocol is supported,
369 - probe: probe routine which will be invoked by the DSA platform device upon
370 registration to test for the presence/absence of a switch device. For MDIO
372 the switch pseudo-PHY and return whether this is a supported device. For other
373 buses, return a non-NULL string
375 - setup: setup function for the switch, this function is responsible for setting
378 configure the switch to separate all network interfaces from each other, that
379 is, they should be isolated by the switch hardware itself, typically by creating
380 a Port-based VLAN ID for each port and allowing only the CPU port and the
382 platform should be disabled. Past this function, the switch is expected to be
384 to issue a software reset of the switch during this setup function in order to
389 -------------------------------
391 - get_phy_flags: Some switches are interfaced to various kinds of Ethernet PHYs,
393 on its own (e.g.: coming from switch memory mapped registers), this function
394 should return a 32-bits bitmask of "flags", that is private between the switch
395 driver and the Ethernet PHY driver in drivers/net/phy/*.
397 - phy_read: Function invoked by the DSA slave MDIO bus when attempting to read
398 the switch port MDIO registers. If unavailable, return 0xffff for each read.
399 For builtin switch Ethernet PHYs, this function should allow reading the link
400 status, auto-negotiation results, link partner pages etc..
402 - phy_write: Function invoked by the DSA slave MDIO bus when attempting to write
403 to the switch port MDIO registers. If unavailable return a negative error
406 - adjust_link: Function invoked by the PHY library when a slave network device
408 configuring the switch port link parameters: speed, duplex, pause based on
411 - fixed_link_update: Function invoked by the PHY library, and specifically by
412 the fixed PHY driver asking the switch driver for link parameters that could
413 not be auto-negotiated, or obtained by reading the PHY registers through MDIO.
415 MoCA or other kinds of non-MDIO managed PHYs where out of band link
419 ------------------
421 - get_strings: ethtool function used to query the driver's strings, will
424 - get_ethtool_stats: ethtool function used to query per-port statistics and
426 RX/TX counters from the network device, with switch driver specific statistics
429 - get_sset_count: ethtool function used to query the number of statistics items
431 - get_wol: ethtool function used to obtain Wake-on-LAN settings per-port, this
433 Wake-on-LAN settings if this interface needs to participate in Wake-on-LAN
435 - set_wol: ethtool function used to configure Wake-on-LAN settings per-port,
438 - set_eee: ethtool function which is used to configure a switch port EEE (Green
439 Ethernet) settings, can optionally invoke the PHY library to enable EEE at the
440 PHY level if relevant. This function should enable EEE at the switch port MAC
441 controller and data-processing logic
443 - get_eee: ethtool function which is used to query a switch port EEE settings,
444 this function should return the EEE state of the switch port MAC controller
445 and data-processing logic as well as query the PHY for its currently configured
448 - get_eeprom_len: ethtool function returning for a given switch the EEPROM
451 - get_eeprom: ethtool function returning for a given switch the EEPROM contents
453 - set_eeprom: ethtool function writing specified data to a given switch EEPROM
455 - get_regs_len: ethtool function returning the register length for a given
456 switch
458 - get_regs: ethtool function returning the Ethernet switch internal register
459 contents. This function might require user-land code in ethtool to
460 pretty-print register values and registers
463 ----------------
465 - suspend: function invoked by the DSA platform device when the system goes to
466 suspend, should quiesce all Ethernet switch activities, but keep ports
467 participating in Wake-on-LAN active as well as additional wake-up logic if
470 - resume: function invoked by the DSA platform device when the system resumes,
471 should resume all Ethernet switch activities and re-configure the switch to be
474 - port_enable: function invoked by the DSA slave network device ndo_open
476 fully enabling a given switch port. DSA takes care of marking the port with
480 - port_disable: function invoked by the DSA slave network device ndo_close
482 fully disabling a given switch port. DSA takes care of marking the port with
487 ------------
489 - port_bridge_join: bridge layer function invoked when a given switch port is
490 added to a bridge, this function should be doing the necessary at the switch
494 - port_bridge_leave: bridge layer function invoked when a given switch port is
496 switch level to deny the leaving port from ingress/egress traffic from the
498 out at the switch hardware for the switch to (re) learn MAC addresses behind
501 - port_stp_state_set: bridge layer function invoked when a given switch port STP
502 state is computed by the bridge layer and should be propagated to switch
503 hardware to forward/block/learn traffic. The switch driver is responsible for
508 ---------------------
510 - port_vlan_filtering: bridge layer function invoked when the bridge gets
515 VLAN ID map/rules. If there is no PVID programmed into the switch port,
516 untagged frames must be rejected as well. When turned off the switch must
520 - port_vlan_prepare: bridge layer function invoked when the bridge prepares the
522 by the hardware, this function should return -EOPNOTSUPP to inform the bridge
526 - port_vlan_add: bridge layer function invoked when a VLAN is configured
527 (tagged or untagged) for the given switch port
529 - port_vlan_del: bridge layer function invoked when a VLAN is removed from the
530 given switch port
532 - port_vlan_dump: bridge layer function invoked with a switchdev callback
536 - port_fdb_prepare: bridge layer function invoked when the bridge prepares the
538 supported, this function should return -EOPNOTSUPP to inform the bridge code
542 - port_fdb_add: bridge layer function invoked when the bridge wants to install a
543 Forwarding Database entry, the switch hardware should be programmed with the
548 of DSA, would be the its port-based VLAN, used by the associated bridge device.
550 - port_fdb_del: bridge layer function invoked when the bridge wants to remove a
551 Forwarding Database entry, the switch hardware should be programmed to delete
555 - port_fdb_dump: bridge layer function invoked with a switchdev callback
559 - port_mdb_prepare: bridge layer function invoked when the bridge prepares the
561 this function should return -EOPNOTSUPP to inform the bridge code to fallback
565 - port_mdb_add: bridge layer function invoked when the bridge wants to install
566 a multicast database entry, the switch hardware should be programmed with the
571 of DSA, would be the its port-based VLAN, used by the associated bridge device.
573 - port_mdb_del: bridge layer function invoked when the bridge wants to remove a
574 multicast database entry, the switch hardware should be programmed to delete
578 - port_mdb_dump: bridge layer function invoked with a switchdev callback
586 -------------------------------------------------------------
589 capable hardware, but does not enforce a strict switch device driver model. On
591 of the switch specific. At some point we should envision a merger between these
595 --------------------
597 - making the number of ports fully dynamic and not dependent on DSA_MAX_PORTS
598 - allowing more than one CPU/management interface:
600 - porting more drivers from other vendors: