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Add pldmfw library for PLDM firmware update
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The pldmfw library is used to implement common logic needed to flash
devices based on firmware files using the format described by the PLDM
for Firmware Update standard.

This library consists of logic to parse the PLDM file format from
a firmware file object, as well as common logic for sending the relevant
PLDM header data to the device firmware.

A simple ops table is provided so that device drivers can implement
device specific hardware interactions while keeping the common logic to
the pldmfw library.

This library will be used by the Intel ice networking driver as part of
implementing device flash update via devlink. The library aims to be
vendor and device agnostic. For this reason, it has been placed in
lib/pldmfw, in the hopes that other devices which use the PLDM firmware
file format may benefit from it in the future. However, do note that not
all features defined in the PLDM standard have been implemented.

Signed-off-by: Jacob Keller <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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jacob-keller authored and davem330 committed Jul 29, 2020
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1 change: 1 addition & 0 deletions Documentation/driver-api/index.rst
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Expand Up @@ -95,6 +95,7 @@ available subsections can be seen below.
phy/index
pti_intel_mid
pwm
pldmfw/index
rfkill
serial/index
sm501
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56 changes: 56 additions & 0 deletions Documentation/driver-api/pldmfw/driver-ops.rst
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.. SPDX-License-Identifier: GPL-2.0-only
=========================
Driver-specific callbacks
=========================

The ``pldmfw`` module relies on the device driver for implementing device
specific behavior using the following operations.

``.match_record``
-----------------

The ``.match_record`` operation is used to determine whether a given PLDM
record matches the device being updated. This requires comparing the record
descriptors in the record with information from the device. Many record
descriptors are defined by the PLDM standard, but it is also allowed for
devices to implement their own descriptors.

The ``.match_record`` operation should return true if a given record matches
the device.

``.send_package_data``
----------------------

The ``.send_package_data`` operation is used to send the device-specific
package data in a record to the device firmware. If the matching record
provides package data, ``pldmfw`` will call the ``.send_package_data``
function with a pointer to the package data and with the package data
length. The device driver should send this data to firmware.

``.send_component_table``
-------------------------

The ``.send_component_table`` operation is used to forward component
information to the device. It is called once for each applicable component,
that is, for each component indicated by the matching record. The
device driver should send the component information to the device firmware,
and wait for a response. The provided transfer flag indicates whether this
is the first, last, or a middle component, and is expected to be forwarded
to firmware as part of the component table information. The driver should an
error in the case when the firmware indicates that the component cannot be
updated, or return zero if the component can be updated.

``.flash_component``
--------------------

The ``.flash_component`` operation is used to inform the device driver to
flash a given component. The driver must perform any steps necessary to send
the component data to the device.

``.finalize_update``
--------------------

The ``.finalize_update`` operation is used by the ``pldmfw`` library in
order to allow the device driver to perform any remaining device specific
logic needed to finish the update.
203 changes: 203 additions & 0 deletions Documentation/driver-api/pldmfw/file-format.rst
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.. SPDX-License-Identifier: GPL-2.0-only
==================================
PLDM Firmware file format overview
==================================

A PLDM firmware package is a binary file which contains a header that
describes the contents of the firmware package. This includes an initial
package header, one or more firmware records, and one or more components
describing the actual flash contents to program.

This diagram provides an overview of the file format::

overall file layout
+----------------------+
| |
| Package Header |
| |
+----------------------+
| |
| Device Records |
| |
+----------------------+
| |
| Component Info |
| |
+----------------------+
| |
| Package Header CRC |
| |
+----------------------+
| |
| Component Image 1 |
| |
+----------------------+
| |
| Component Image 2 |
| |
+----------------------+
| |
| ... |
| |
+----------------------+
| |
| Component Image N |
| |
+----------------------+

Package Header
==============

The package header begins with the UUID of the PLDM file format, and
contains information about the version of the format that the file uses. It
also includes the total header size, a release date, the size of the
component bitmap, and an overall package version.

The following diagram provides an overview of the package header::

header layout
+-------------------------+
| PLDM UUID |
+-------------------------+
| Format Revision |
+-------------------------+
| Header Size |
+-------------------------+
| Release Date |
+-------------------------+
| Component Bitmap Length |
+-------------------------+
| Package Version Info |
+-------------------------+

Device Records
==============

The device firmware records area starts with a count indicating the total
number of records in the file, followed by each record. A single device
record describes what device matches this record. All valid PLDM firmware
files must contain at least one record, but optionally may contain more than
one record if they support multiple devices.

Each record will identify the device it supports via TLVs that describe the
device, such as the PCI device and vendor information. It will also indicate
which set of components that are used by this device. It is possible that
only subset of provided components will be used by a given record. A record
may also optionally contain device-specific package data that will be used
by the device firmware during the update process.

The following diagram provides an overview of the device record area::

area layout
+---------------+
| |
| Record Count |
| |
+---------------+
| |
| Record 1 |
| |
+---------------+
| |
| Record 2 |
| |
+---------------+
| |
| ... |
| |
+---------------+
| |
| Record N |
| |
+---------------+

record layout
+-----------------------+
| Record Length |
+-----------------------+
| Descriptor Count |
+-----------------------+
| Option Flags |
+-----------------------+
| Version Settings |
+-----------------------+
| Package Data Length |
+-----------------------+
| Applicable Components |
+-----------------------+
| Version String |
+-----------------------+
| Descriptor TLVs |
+-----------------------+
| Package Data |
+-----------------------+

Component Info
==============

The component information area begins with a count of the number of
components. Following this count is a description for each component. The
component information points to the location in the file where the component
data is stored, and includes version data used to identify the version of
the component.

The following diagram provides an overview of the component area::

area layout
+-----------------+
| |
| Component Count |
| |
+-----------------+
| |
| Component 1 |
| |
+-----------------+
| |
| Component 2 |
| |
+-----------------+
| |
| ... |
| |
+-----------------+
| |
| Component N |
| |
+-----------------+

component layout
+------------------------+
| Classification |
+------------------------+
| Component Identifier |
+------------------------+
| Comparison Stamp |
+------------------------+
| Component Options |
+------------------------+
| Activation Method |
+------------------------+
| Location Offset |
+------------------------+
| Component Size |
+------------------------+
| Component Version Info |
+------------------------+
| Package Data |
+------------------------+


Package Header CRC
==================

Following the component information is a short 4-byte CRC calculated over
the contents of all of the header information.

Component Images
================

The component images follow the package header information in the PLDM
firmware file. Each of these is simply a binary chunk with its start and
size defined by the matching component structure in the component info area.
72 changes: 72 additions & 0 deletions 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.
7 changes: 7 additions & 0 deletions MAINTAINERS
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Expand Up @@ -13604,6 +13604,13 @@ S: Maintained
F: Documentation/devicetree/bindings/iio/chemical/plantower,pms7003.yaml
F: drivers/iio/chemical/pms7003.c

PLDMFW LIBRARY
M: Jacob Keller <[email protected]>
S: Maintained
F: Documentation/driver-api/pldmfw/
F: include/linux/pldmfw.h
F: lib/pldmfw/

PLX DMA DRIVER
M: Logan Gunthorpe <[email protected]>
S: Maintained
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