Hi,
This patchset brings support for Silicon Labs' CPC protocol as transport layer for Greybus. This is introduced as a module that sits between Greybus and CPC Host Device Drivers implementations, like SDIO or SPI. This patchset includes SDIO as physical layer.
+----------------------------------------------------+ | Greybus | +----------------------------------------------------+ /|\ | |/ +----------------------------------------------------+ | CPC | +----------------------------------------------------+ /|\ /|\ /|\ | | | |/ |/ |/ +----------+ +---------+ +-----------+ | SDIO | | SPI | | Others | +----------+ +---------+ +-----------+
CPC implements 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, but that feature is not part of the RFC to keep it concise. There's also a flow-control feature, preventing sending messages to already full cports.
In order to implement these features, a 4-byte header is prepended to Greybus messages, making the whole header 12 bytes (Greybus header is 8 bytes).
This RFC starts by implementing a shim layer 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. Finally, an SDIO driver is added to enable the communication with a remote device.
Changes in v2: - addressed review comments and errors reported by kernel bot - for SDIO driver, remove padding between headers and payloads when aggregating packets together
Damien Riégel (13): 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 greybus: cpc: add private data pointer in CPC Host Device
Gabriel Beaulieu (1): greybus: cpc: add CPC SDIO host driver
MAINTAINERS | 6 + drivers/greybus/Kconfig | 2 + drivers/greybus/Makefile | 2 + drivers/greybus/cpc/Kconfig | 22 ++ drivers/greybus/cpc/Makefile | 9 + drivers/greybus/cpc/cpc.h | 75 +++++ drivers/greybus/cpc/cport.c | 112 +++++++ drivers/greybus/cpc/header.c | 136 +++++++++ drivers/greybus/cpc/header.h | 55 ++++ drivers/greybus/cpc/host.c | 313 +++++++++++++++++++ drivers/greybus/cpc/host.h | 63 ++++ drivers/greybus/cpc/protocol.c | 168 +++++++++++ drivers/greybus/cpc/sdio.c | 533 +++++++++++++++++++++++++++++++++ 13 files changed, 1496 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 create mode 100644 drivers/greybus/cpc/sdio.c