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| -rw-r--r-- | Documentation/driver-api/pldmfw/driver-ops.rst | 56 | ||||
| -rw-r--r-- | Documentation/driver-api/pldmfw/file-format.rst | 203 | ||||
| -rw-r--r-- | Documentation/driver-api/pldmfw/index.rst | 72 |
3 files changed, 331 insertions, 0 deletions
diff --git a/Documentation/driver-api/pldmfw/driver-ops.rst b/Documentation/driver-api/pldmfw/driver-ops.rst new file mode 100644 index 000000000..f0654783d --- /dev/null +++ b/Documentation/driver-api/pldmfw/driver-ops.rst @@ -0,0 +1,56 @@ +.. 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. diff --git a/Documentation/driver-api/pldmfw/file-format.rst b/Documentation/driver-api/pldmfw/file-format.rst new file mode 100644 index 000000000..b7a9cebe0 --- /dev/null +++ b/Documentation/driver-api/pldmfw/file-format.rst @@ -0,0 +1,203 @@ +.. 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. diff --git a/Documentation/driver-api/pldmfw/index.rst b/Documentation/driver-api/pldmfw/index.rst new file mode 100644 index 000000000..ad2c33ece --- /dev/null +++ b/Documentation/driver-api/pldmfw/index.rst @@ -0,0 +1,72 @@ +.. 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. |