73 lines
2.8 KiB
ReStructuredText
73 lines
2.8 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0-only
|
|
|
|
==================================
|
|
PLDM Firmware Flash Update Library
|
|
==================================
|
|
|
|
``pldmfw`` implements functionality for updating the flash on a device using
|
|
the PLDM for Firmware Update standard
|
|
<https://www.dmtf.org/documents/pmci/pldm-firmware-update-specification-100>.
|
|
|
|
.. toctree::
|
|
:maxdepth: 1
|
|
|
|
file-format
|
|
driver-ops
|
|
|
|
==================================
|
|
Overview of the ``pldmfw`` library
|
|
==================================
|
|
|
|
The ``pldmfw`` library is intended to be used by device drivers for
|
|
implementing device flash update based on firmware files following the PLDM
|
|
firwmare file format.
|
|
|
|
It is implemented using an ops table that allows device drivers to provide
|
|
the underlying device specific functionality.
|
|
|
|
``pldmfw`` implements logic to parse the packed binary format of the PLDM
|
|
firmware file into data structures, and then uses the provided function
|
|
operations to determine if the firmware file is a match for the device. If
|
|
so, it sends the record and component data to the firmware using the device
|
|
specific implementations provided by device drivers. Once the device
|
|
firmware indicates that the update may be performed, the firmware data is
|
|
sent to the device for programming.
|
|
|
|
Parsing the PLDM file
|
|
=====================
|
|
|
|
The PLDM file format uses packed binary data, with most multi-byte fields
|
|
stored in the Little Endian format. Several pieces of data are variable
|
|
length, including version strings and the number of records and components.
|
|
Due to this, it is not straight forward to index the record, record
|
|
descriptors, or components.
|
|
|
|
To avoid proliferating access to the packed binary data, the ``pldmfw``
|
|
library parses and extracts this data into simpler structures for ease of
|
|
access.
|
|
|
|
In order to safely process the firmware file, care is taken to avoid
|
|
unaligned access of multi-byte fields, and to properly convert from Little
|
|
Endian to CPU host format. Additionally the records, descriptors, and
|
|
components are stored in linked lists.
|
|
|
|
Performing a flash update
|
|
=========================
|
|
|
|
To perform a flash update, the ``pldmfw`` module performs the following
|
|
steps
|
|
|
|
1. Parse the firmware file for record and component information
|
|
2. Scan through the records and determine if the device matches any record
|
|
in the file. The first matched record will be used.
|
|
3. If the matching record provides package data, send this package data to
|
|
the device.
|
|
4. For each component that the record indicates, send the component data to
|
|
the device. For each component, the firmware may respond with an
|
|
indication of whether the update is suitable or not. If any component is
|
|
not suitable, the update is canceled.
|
|
5. For each component, send the binary data to the device firmware for
|
|
updating.
|
|
6. After all components are programmed, perform any final device-specific
|
|
actions to finalize the update.
|