1.. SPDX-License-Identifier: GPL-2.0-only 2 3================================== 4PLDM Firmware Flash Update Library 5================================== 6 7``pldmfw`` implements functionality for updating the flash on a device using 8the PLDM for Firmware Update standard 9<https://www.dmtf.org/documents/pmci/pldm-firmware-update-specification-100>. 10 11.. toctree:: 12 :maxdepth: 1 13 14 file-format 15 driver-ops 16 17================================== 18Overview of the ``pldmfw`` library 19================================== 20 21The ``pldmfw`` library is intended to be used by device drivers for 22implementing device flash update based on firmware files following the PLDM 23firmware file format. 24 25It is implemented using an ops table that allows device drivers to provide 26the underlying device specific functionality. 27 28``pldmfw`` implements logic to parse the packed binary format of the PLDM 29firmware file into data structures, and then uses the provided function 30operations to determine if the firmware file is a match for the device. If 31so, it sends the record and component data to the firmware using the device 32specific implementations provided by device drivers. Once the device 33firmware indicates that the update may be performed, the firmware data is 34sent to the device for programming. 35 36Parsing the PLDM file 37===================== 38 39The PLDM file format uses packed binary data, with most multi-byte fields 40stored in the Little Endian format. Several pieces of data are variable 41length, including version strings and the number of records and components. 42Due to this, it is not straight forward to index the record, record 43descriptors, or components. 44 45To avoid proliferating access to the packed binary data, the ``pldmfw`` 46library parses and extracts this data into simpler structures for ease of 47access. 48 49In order to safely process the firmware file, care is taken to avoid 50unaligned access of multi-byte fields, and to properly convert from Little 51Endian to CPU host format. Additionally the records, descriptors, and 52components are stored in linked lists. 53 54Performing a flash update 55========================= 56 57To perform a flash update, the ``pldmfw`` module performs the following 58steps 59 601. Parse the firmware file for record and component information 612. Scan through the records and determine if the device matches any record 62 in the file. The first matched record will be used. 633. If the matching record provides package data, send this package data to 64 the device. 654. For each component that the record indicates, send the component data to 66 the device. For each component, the firmware may respond with an 67 indication of whether the update is suitable or not. If any component is 68 not suitable, the update is canceled. 695. For each component, send the binary data to the device firmware for 70 updating. 716. After all components are programmed, perform any final device-specific 72 actions to finalize the update. 73