.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)

============
Devlink Info
============

The ``devlink-info`` mechanism enables device drivers to report device
(hardware and firmware) information in a standard, extensible fashion.

The original motivation for the ``devlink-info`` API was twofold:

 - making it possible to automate device and firmware management in a fleet
   of machines in a vendor-independent fashion (see also
   :ref:`Documentation/networking/devlink/devlink-flash.rst <devlink_flash>`);
 - name the per component FW versions (as opposed to the crowded ethtool
   version string).

``devlink-info`` supports reporting multiple types of objects. Reporting driver
versions is generally discouraged - here, and via any other Linux API.

.. list-table:: List of top level info objects
   :widths: 5 95

   * - Name
     - Description
   * - ``driver``
     - Name of the currently used device driver, also available through sysfs.

   * - ``serial_number``
     - Serial number of the device.

       This is usually the serial number of the ASIC, also often available
       in PCI config space of the device in the *Device Serial Number*
       capability.

       The serial number should be unique per physical device.
       Sometimes the serial number of the device is only 48 bits long (the
       length of the Ethernet MAC address), and since PCI DSN is 64 bits long
       devices pad or encode additional information into the serial number.
       One example is adding port ID or PCI interface ID in the extra two bytes.
       Drivers should make sure to strip or normalize any such padding
       or interface ID, and report only the part of the serial number
       which uniquely identifies the hardware. In other words serial number
       reported for two ports of the same device or on two hosts of
       a multi-host device should be identical.

       .. note:: ``devlink-info`` API should be extended with a new field
	  if devices want to report board/product serial number (often
	  reported in PCI *Vital Product Data* capability).

   * - ``fixed``
     - Group for hardware identifiers, and versions of components
       which are not field-updatable.

       Versions in this section identify the device design. For example,
       component identifiers or the board version reported in the PCI VPD.
       Data in ``devlink-info`` should be broken into the smallest logical
       components, e.g. PCI VPD may concatenate various information
       to form the Part Number string, while in ``devlink-info`` all parts
       should be reported as separate items.

       This group must not contain any frequently changing identifiers,
       such as serial numbers. See
       :ref:`Documentation/networking/devlink/devlink-flash.rst <devlink_flash>`
       to understand why.

   * - ``running``
     - Group for information about currently running software/firmware.
       These versions often only update after a reboot, sometimes device reset.

   * - ``stored``
     - Group for software/firmware versions in device flash.

       Stored values must update to reflect changes in the flash even
       if reboot has not yet occurred. If device is not capable of updating
       ``stored`` versions when new software is flashed, it must not report
       them.

Each version can be reported at most once in each version group. Firmware
components stored on the flash should feature in both the ``running`` and
``stored`` sections, if device is capable of reporting ``stored`` versions
(see :ref:`Documentation/networking/devlink/devlink-flash.rst <devlink_flash>`).
In case software/firmware components are loaded from the disk (e.g.
``/lib/firmware``) only the running version should be reported via
the kernel API.

Generic Versions
================

It is expected that drivers use the following generic names for exporting
version information. If a generic name for a given component doesn't exist yet,
driver authors should consult existing driver-specific versions and attempt
reuse. As last resort, if a component is truly unique, using driver-specific
names is allowed, but these should be documented in the driver-specific file.

All versions should try to use the following terminology:

.. list-table:: List of common version suffixes
   :widths: 10 90

   * - Name
     - Description
   * - ``id``, ``revision``
     - Identifiers of designs and revision, mostly used for hardware versions.

   * - ``api``
     - Version of API between components. API items are usually of limited
       value to the user, and can be inferred from other versions by the vendor,
       so adding API versions is generally discouraged as noise.

   * - ``bundle_id``
     - Identifier of a distribution package which was flashed onto the device.
       This is an attribute of a firmware package which covers multiple versions
       for ease of managing firmware images (see
       :ref:`Documentation/networking/devlink/devlink-flash.rst <devlink_flash>`).

       ``bundle_id`` can appear in both ``running`` and ``stored`` versions,
       but it must not be reported if any of the components covered by the
       ``bundle_id`` was changed and no longer matches the version from
       the bundle.

board.id
--------

Unique identifier of the board design.

board.rev
---------

Board design revision.

asic.id
-------

ASIC design identifier.

asic.rev
--------

ASIC design revision/stepping.

board.manufacture
-----------------

An identifier of the company or the facility which produced the part.

fw
--

Overall firmware version, often representing the collection of
fw.mgmt, fw.app, etc.

fw.mgmt
-------

Control unit firmware version. This firmware is responsible for house
keeping tasks, PHY control etc. but not the packet-by-packet data path
operation.

fw.mgmt.api
-----------

Firmware interface specification version of the software interfaces between
driver and firmware.

fw.app
------

Data path microcode controlling high-speed packet processing.

fw.undi
-------

UNDI software, may include the UEFI driver, firmware or both.

fw.ncsi
-------

Version of the software responsible for supporting/handling the
Network Controller Sideband Interface.

fw.psid
-------

Unique identifier of the firmware parameter set. These are usually
parameters of a particular board, defined at manufacturing time.

fw.roce
-------

RoCE firmware version which is responsible for handling roce
management.

fw.bundle_id
------------

Unique identifier of the entire firmware bundle.

Future work
===========

The following extensions could be useful:

 - product serial number - NIC boards often get labeled with a board serial
   number rather than ASIC serial number; it'd be useful to add board serial
   numbers to the API if they can be retrieved from the device;

 - on-disk firmware file names - drivers list the file names of firmware they
   may need to load onto devices via the ``MODULE_FIRMWARE()`` macro. These,
   however, are per module, rather than per device. It'd be useful to list
   the names of firmware files the driver will try to load for a given device,
   in order of priority.