--- /dev/null
+.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+.. _devlink_flash:
+
+=============
+Devlink Flash
+=============
+
+The ``devlink-flash`` API allows updating device firmware. It replaces the
+older ``ethtool-flash`` mechanism, and doesn't require taking any
+networking locks in the kernel to perform the flash update. Example use::
+
+ $ devlink dev flash pci/0000:05:00.0 file flash-boot.bin
+
+Note that the file name is a path relative to the firmware loading path
+(usually ``/lib/firmware/``). Drivers may send status updates to inform
+user space about the progress of the update operation.
+
+Firmware Loading
+================
+
+Devices which require firmware to operate usually store it in non-volatile
+memory on the board, e.g. flash. Some devices store only basic firmware on
+the board, and the driver loads the rest from disk during probing.
+``devlink-info`` allows users to query firmware information (loaded
+components and versions).
+
+In other cases the device can both store the image on the board, load from
+disk, or automatically flash a new image from disk. The ``fw_load_policy``
+devlink parameter can be used to control this behavior
+(:ref:`Documentation/networking/devlink/devlink-params.rst <devlink_params_generic>`).
+
+On-disk firmware files are usually stored in ``/lib/firmware/``.
+
+Firmware Version Management
+===========================
+
+Drivers are expected to implement ``devlink-flash`` and ``devlink-info``
+functionality, which together allow for implementing vendor-independent
+automated firmware update facilities.
+
+``devlink-info`` exposes the ``driver`` name and three version groups
+(``fixed``, ``running``, ``stored``).
+
+The ``driver`` attribute and ``fixed`` group identify the specific device
+design, e.g. for looking up applicable firmware updates. This is why
+``serial_number`` is not part of the ``fixed`` versions (even though it
+is fixed) - ``fixed`` versions should identify the design, not a single
+device.
+
+``running`` and ``stored`` firmware versions identify the firmware running
+on the device, and firmware which will be activated after reboot or device
+reset.
+
+The firmware update agent is supposed to be able to follow this simple
+algorithm to update firmware contents, regardless of the device vendor:
+
+.. code-block:: sh
+
+ # Get unique HW design identifier
+ $hw_id = devlink-dev-info['fixed']
+
+ # Find out which FW flash we want to use for this NIC
+ $want_flash_vers = some-db-backed.lookup($hw_id, 'flash')
+
+ # Update flash if necessary
+ if $want_flash_vers != devlink-dev-info['stored']:
+ $file = some-db-backed.download($hw_id, 'flash')
+ devlink-dev-flash($file)
+
+ # Find out the expected overall firmware versions
+ $want_fw_vers = some-db-backed.lookup($hw_id, 'all')
+
+ # Update on-disk file if necessary
+ if $want_fw_vers != devlink-dev-info['running']:
+ $file = some-db-backed.download($hw_id, 'disk')
+ write($file, '/lib/firmware/')
+
+ # Try device reset, if available
+ if $want_fw_vers != devlink-dev-info['running']:
+ devlink-reset()
+
+ # Reboot, if reset wasn't enough
+ if $want_fw_vers != devlink-dev-info['running']:
+ reboot()
+
+Note that each reference to ``devlink-dev-info`` in this pseudo-code
+is expected to fetch up-to-date information from the kernel.
+
+For the convenience of identifying firmware files some vendors add
+``bundle_id`` information to the firmware versions. This meta-version covers
+multiple per-component versions and can be used e.g. in firmware file names
+(all component versions could get rather long.)
============
The ``devlink-info`` mechanism enables device drivers to report device
-information in a generic fashion. It is extensible, and enables exporting
-even device or driver specific information.
+(hardware and firmware) information in a standard, extensible fashion.
-devlink supports representing the following types of versions
+The original motivation for the ``devlink-info`` API was twofold:
-.. list-table:: List of version types
+ - 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
- * - Type
+ * - 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``
- - Represents fixed versions, which cannot change. For example,
+ - 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``
- - Represents the version of the currently running component. For
- example the running version of firmware. These versions generally
- only update after a reboot.
+ - Group for information about currently running software/firmware.
+ These versions often only update after a reboot, sometimes device reset.
+
* - ``stored``
- - Represents the version of a component as stored, such as after a
- flash update. Stored values should update to reflect changes in the
- flash even if a reboot has not yet occurred.
+ - 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. Other information may be exposed using driver-specific
-names, but these should be documented in the driver-specific file.
+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
--------
asic.rev
--------
-ASIC design revision.
+ASIC design revision/stepping.
board.manufacture
-----------------
fw.psid
-------
-Unique identifier of the firmware parameter set.
+Unique identifier of the firmware parameter set. These are usually
+parameters of a particular board, defined at manufacturing time.
fw.roce
-------
------------
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.
projects / platform / kernel / linux-starfive.git / commitdiff