linux-kernel - [RFC PATCH v2 00/12] greybus: introduce CPC as transport layer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251114150738.32426-1-damien.riegel@silabs.com>
Date: Fri, 14 Nov 2025 10:07:26 -0500
From: Damien Riégel <damien.riegel@...abs.com>
To: greybus-dev@...ts.linaro.org, Johan Hovold <johan@...nel.org>,
        Alex Elder <elder@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc: Silicon Labs Kernel Team <linux-devel@...abs.com>,
        Damien Riégel <damien.riegel@...abs.com>
Subject: [RFC PATCH v2 00/12] greybus: introduce CPC as transport layer

Hi,

This patchset brings support for Silicon Labs' CPC (Co-Processor
Communication) protocol as transport layer for Greybus. This is
introduced as a module that sits between Greybus and CPC Host Device
Driver implementations, like SDIO or SPI, which are not part of this
RFC. If there's no push back with this RFC, the final patchset ready for
upstream will include the SDIO driver.

The goal of this module is to implement some of the features of Unipro
that Greybus relies upon, like reliable transmission. CPC takes care of
detecting transmission errors and retransmit frames if necessary. That
feature is not part of the RFC to keep it concise, but it's planned for
a future patchset. There's also a flow-control feature, to prevent from
sending messages to cports that don't have anymore room.

In order to implement these features, a 4-byte header is prepended to
Greybus messages, making the whole header 12 bytes (Greybus header
itself being 8 bytes).

This RFC starts by implementing a shim layer that sits between physical
bus drivers (like SDIO and SPI) and Greybus, and progressively add more
elements to it to make it useful in its own right.

    +----------------------------------------------------+
    |                      Greybus                       |
    +----------------------------------------------------+
			     /|\
			      |
			     \|/
    +----------------------------------------------------+
    |                        CPC                         |
    +----------------------------------------------------+
	  /|\                /|\                /|\
	   |                  |                  |
	  \|/                \|/                \|/
      +----------+       +---------+       +-----------+
      |   SDIO   |       |   SPI   |       |   Others  |
      +----------+       +---------+       +-----------+


Changes in v2:
 - v1 included a new protocol for Bluetooth HCI, this has been dropped
   to focus on CPC itself
 - likewise, there was an SPI driver, it has been dropped of this RFC
   for the same reason
 - v1 introduced CPC in a big commit, this time it's been split in
   smaller commits to make review manageable

Damien Riégel (12):
  greybus: cpc: add minimal CPC Host Device infrastructure
  greybus: cpc: introduce CPC cport structure
  greybus: cpc: use socket buffers instead of gb_message in TX path
  greybus: cpc: pack cport ID in Greybus header
  greybus: cpc: switch RX path to socket buffers
  greybus: cpc: introduce CPC header structure
  greybus: cpc: account for CPC header size in RX and TX path
  greybus: cpc: add and validate sequence numbers
  greybus: cpc: acknowledge all incoming messages
  greybus: cpc: use holding queue instead of sending out immediately
  greybus: cpc: honour remote's RX window
  greybus: cpc: let host device drivers dequeue TX frames

 MAINTAINERS                    |   6 +
 drivers/greybus/Kconfig        |   2 +
 drivers/greybus/Makefile       |   2 +
 drivers/greybus/cpc/Kconfig    |  10 ++
 drivers/greybus/cpc/Makefile   |   6 +
 drivers/greybus/cpc/cpc.h      |  76 +++++++++
 drivers/greybus/cpc/cport.c    | 107 ++++++++++++
 drivers/greybus/cpc/header.c   | 146 +++++++++++++++++
 drivers/greybus/cpc/header.h   |  54 +++++++
 drivers/greybus/cpc/host.c     | 287 +++++++++++++++++++++++++++++++++
 drivers/greybus/cpc/host.h     |  58 +++++++
 drivers/greybus/cpc/protocol.c | 169 +++++++++++++++++++
 12 files changed, 923 insertions(+)
 create mode 100644 drivers/greybus/cpc/Kconfig
 create mode 100644 drivers/greybus/cpc/Makefile
 create mode 100644 drivers/greybus/cpc/cpc.h
 create mode 100644 drivers/greybus/cpc/cport.c
 create mode 100644 drivers/greybus/cpc/header.c
 create mode 100644 drivers/greybus/cpc/header.h
 create mode 100644 drivers/greybus/cpc/host.c
 create mode 100644 drivers/greybus/cpc/host.h
 create mode 100644 drivers/greybus/cpc/protocol.c

-- 
2.49.0