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+.. 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.
+
+ * - ``board.serial_number``
+ - Board serial number of the device.
+
+ This is usually the serial number of the board, often available in
+ PCI *Vital Product Data*.
+
+ * - ``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.
+
+fw.bootloader
+-------------
+
+Version of the bootloader.
+
+Future work
+===========
+
+The following extensions could be useful:
+
+ - 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.