devlink-linecard.rst

  1.. SPDX-License-Identifier: GPL-2.0
  2
  3=================
  4Devlink Line card
  5=================
  6
  7Background
  8==========
  9
 10The ``devlink-linecard`` mechanism is targeted for manipulation of
 11line cards that serve as a detachable PHY modules for modular switch
 12system. Following operations are provided:
 13
 14  * Get a list of supported line card types.
 15  * Provision of a slot with specific line card type.
 16  * Get and monitor of line card state and its change.
 17
 18Line card according to the type may contain one or more gearboxes
 19to mux the lanes with certain speed to multiple ports with lanes
 20of different speed. Line card ensures N:M mapping between
 21the switch ASIC modules and physical front panel ports.
 22
 23Overview
 24========
 25
 26Each line card devlink object is created by device driver,
 27according to the physical line card slots available on the device.
 28
 29Similar to splitter cable, where the device might have no way
 30of detection of the splitter cable geometry, the device
 31might not have a way to detect line card type. For that devices,
 32concept of provisioning is introduced. It allows the user to:
 33
 34  * Provision a line card slot with certain line card type
 35
 36    - Device driver would instruct the ASIC to prepare all
 37      resources accordingly. The device driver would
 38      create all instances, namely devlink port and netdevices
 39      that reside on the line card, according to the line card type
 40  * Manipulate of line card entities even without line card
 41    being physically connected or powered-up
 42  * Setup splitter cable on line card ports
 43
 44    - As on the ordinary ports, user may provision a splitter
 45      cable of a certain type, without the need to
 46      be physically connected to the port
 47  * Configure devlink ports and netdevices
 48
 49Netdevice carrier is decided as follows:
 50
 51  * Line card is not inserted or powered-down
 52
 53    - The carrier is always down
 54  * Line card is inserted and powered up
 55
 56    - The carrier is decided as for ordinary port netdevice
 57
 58Line card state
 59===============
 60
 61The ``devlink-linecard`` mechanism supports the following line card states:
 62
 63  * ``unprovisioned``: Line card is not provisioned on the slot.
 64  * ``unprovisioning``: Line card slot is currently being unprovisioned.
 65  * ``provisioning``: Line card slot is currently in a process of being provisioned
 66    with a line card type.
 67  * ``provisioning_failed``: Provisioning was not successful.
 68  * ``provisioned``: Line card slot is provisioned with a type.
 69  * ``active``: Line card is powered-up and active.
 70
 71The following diagram provides a general overview of ``devlink-linecard``
 72state transitions::
 73
 74                                          +-------------------------+
 75                                          |                         |
 76       +---------------------------------->      unprovisioned      |
 77       |                                  |                         |
 78       |                                  +--------|-------^--------+
 79       |                                           |       |
 80       |                                           |       |
 81       |                                  +--------v-------|--------+
 82       |                                  |                         |
 83       |                                  |       provisioning      |
 84       |                                  |                         |
 85       |                                  +------------|------------+
 86       |                                               |
 87       |                 +-----------------------------+
 88       |                 |                             |
 89       |    +------------v------------+   +------------v------------+   +-------------------------+
 90       |    |                         |   |                         ---->                         |
 91       +-----   provisioning_failed   |   |       provisioned       |   |         active          |
 92       |    |                         |   |                         <----                         |
 93       |    +------------^------------+   +------------|------------+   +-------------------------+
 94       |                 |                             |
 95       |                 |                             |
 96       |                 |                +------------v------------+
 97       |                 |                |                         |
 98       |                 |                |     unprovisioning      |
 99       |                 |                |                         |
100       |                 |                +------------|------------+
101       |                 |                             |
102       |                 +-----------------------------+
103       |                                               |
104       +-----------------------------------------------+
105
106
107Example usage
108=============
109
110.. code:: shell
111
112    $ devlink lc show [ DEV [ lc LC_INDEX ] ]
113    $ devlink lc set DEV lc LC_INDEX [ { type LC_TYPE | notype } ]
114
115    # Show current line card configuration and status for all slots:
116    $ devlink lc
117
118    # Set slot 8 to be provisioned with type "16x100G":
119    $ devlink lc set pci/0000:01:00.0 lc 8 type 16x100G
120
121    # Set slot 8 to be unprovisioned:
122    $ devlink lc set pci/0000:01:00.0 lc 8 notype