Implement GetPLDMVersion command

This commit implements the GetPLDMVersion which is required
as part of the base PLDM support to know the version of a
given PLDM type.

Change-Id: I1bcbd938c5b6833f62e0ee2f474b04d76b6970d9
Signed-off-by: Sampa Misra <sampmisr@in.ibm.com>
6 files changed
tree: d5a138c74002aca68c26442085607be2fe70b877
  1. libpldm/
  2. libpldmresponder/
  3. test/
  4. .clang-format
  5. .gitignore
  6. bootstrap.sh
  7. configure.ac
  8. LICENSE
  9. MAINTAINERS
  10. Makefile.am
  11. README.md
README.md

Code Organization

At a high-level, code in this repository belongs to one of the following three components.

libpldm

This is a library which deals with the encoding and decoding of PLDM messages. It should be possible to use this library by projects other than OpenBMC, and hence certain constraints apply to it:

  • keeping it light weight
  • implementation in C
  • minimal dynamic memory allocations
  • endian-safe
  • no OpenBMC specific dependencies

Source files are named according to the PLDM Type, for eg base.[h/c], fru.[h/c], etc.

Given a PLDM command "foo", the library will provide the following API: For the Requester function:

encode_foo_req() - encode a foo request
decode_foo_resp() - decode a response to foo

For the Responder function:

decode_foo_req() - decode a foo request
encode_foo_resp() - encode a response to foo

The library also provides API to pack and unpack PLDM headers.

libpldmresponder

This library provides handlers for incoming PLDM request messages. It provides for a registration as well as a plug-in mechanism. The library is implemented in modern C++, and handles OpenBMC's platform specifics.

The handlers are of the form

Response handler(Request payload, size_t payloadLen)

Source files are named according to the PLDM Type, for eg base.[hpp/cpp], fru.[hpp/cpp], etc.

daemon

This is the PLDM daemon application that deals with various aspects of the requester and responder functions, as explained at https://github.com/openbmc/docs/blob/master/designs/pldm-stack.md.

TODO

Consider hosting libpldm above in a repo of its own, probably even outside the OpenBMC project? A separate repo would enable something like git submodule.

Flows

This section documents important code flow paths.

BMC as PLDM responder

a) PLDM daemon receives PLDM request message from underlying transport (MCTP). b) PLDM daemon routes message to message handler, based on the PLDM command. c) Message handler decodes request payload into various field(s) of the request message. It can make use of a decode_foo_req() API, and doesn't have to perform deserialization of the request payload by itself. d) Message handler works with the request field(s) and generates response field(s). e) Message handler prepares a response message. It can make use of an encode_foo_resp() API, and doesn't have to perform the serialization of the response field(s) by itself. f) The PLDM daemon sends the response message prepared at step e) to the remote PLDM device.

BMC as PLDM requester

a) A BMC PLDM requester app prepares a PLDM request message. There would be several requester apps (based on functionality/PLDM remote device). Each of them needn't bother with the serialization of request field(s), and can instead make use of an encode_foo_req() API. b) BMC requester app requests PLDM daemon to send the request message to remote PLDM device. c) Once the PLDM daemon receives a corresponding response message, it notifies the requester app. d) The requester app has to work with the response field(s). It can make use of a decode_foo_resp() API to deserialize the response message.