[PATCH v2 0/3] MCTP over PCC

admiyo
2024-06-19T20:06:03Z

From: Adam Young <admiyo@os.amperecomputing.com>

This series adds support for the Management Control Transport Protocol (MCTP)
over the Platform Communication Channel (PCC) mechanism.

MCTP defines a communication model intended to
facilitate communication between Management controllers
and other management controllers, and between Management
controllers and management devices

PCC is a mechanism for communication between components within
the Platform. It is a composed of shared memory regions,
interrupt registers, and status registers.

The MCTP over PCC driver makes use of two PCC channels. For
sending messages, it uses a Type 3 channel, and for receiving
messages it uses the paired Type 4 channel. The device
and corresponding channels are specified via ACPI.

The first patch in the series implements a mechanism to allow the driver
to indicate whether an ACK should be sent back to the caller
after processing the interrupt. This is an optional feature in
the PCC code, but has been made explicitly required in another driver.
The implementation here maintains the backwards compatibility of that
driver.

The second patch in the series is the required change from ACPICA
code that will be imported into the Linux kernel when synchronized
with the ACPICA repository. It ahs already merged there and will
be merged in as is. It is included here so that the patch series
can run and be tested prior to that merge.

Changes in V3
- removed unused header
- removed spurious space
- removed spurious semis after functiomns
- removed null assignment for init
- remove redundant set of device on skb
- tabify constant declarations
- added rtnl_link_stats64 function
- set MTU to minimum to start
- clean up logic on driver removal
- remove cast on void * assignment
- call cleanup function directly
- check received length before allocating skb
- introduce symbolic constatn for ACK FLAG MASK
- symbolic constant for PCC header flag.
- Add namespace ID to PCC magic
- replaced readls with copy from io of PCC header

Changes in V2

- All Variable Declarations are in reverse Xmass Tree Format
- All Checkpatch Warnings Are Fixed
- Removed Dead code
- Added packet tx/rx stats
- Removed network physical address. This is still in
disucssion in the spec, and will be added once there
is consensus. The protocol can be used with out it.
This also lead to the removal of the Big Endian
conversions.
- Avoided using non volatile pointers in copy to and from io space
- Reorderd the patches to put the ACK check for the PCC Mailbox
as a pre-requisite. The corresponding change for the MCTP
driver has been inlined in the main patch.
- Replaced magic numbers with constants, fixed typos, and other
minor changes from code review.

Code Review Change not made

- Did not change the module init unload function to use the
ACPI equivalent as they do not remove all devices prior
to unload, leading to dangling references and seg faults.

Adam Young (3):
mctp pcc: Check before sending MCTP PCC response ACK
mctp pcc: Allow PCC Data Type in MCTP resource.
mctp pcc: Implement MCTP over PCC Transport

drivers/acpi/acpica/rsaddr.c | 2 +-
drivers/mailbox/pcc.c | 5 +-
drivers/net/mctp/Kconfig | 13 ++
drivers/net/mctp/Makefile | 1 +
drivers/net/mctp/mctp-pcc.c | 373 +++++++++++++++++++++++++++++++++++
include/acpi/pcc.h | 1 +
6 files changed, 393 insertions(+), 2 deletions(-)
create mode 100644 drivers/net/mctp/mctp-pcc.c

--
2.34.1