Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 72 insertions, 0 deletions

diff --git a/Documentation/driver-api/pldmfw/index.rst b/Documentation/driver-api/pldmfw/index.rst
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+.. 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.