[PATCH v5 00/16] introduce a generic IOCTL interface for RPMsg channels management

Arnaud Pouliquen
2021-02-19T11:19:20Z

This series restructures the RPMsg char driver to decorrelate the control part and to
create a generic RPMsg ioctl interface compatible with other RPMsg services.

The V4 and V5 fix compilation issues reported by the kernel test robot <lkp@intel.com>
and analyzed by Dan Carpenter <dan.carpenter@oracle.com>.

The V3 is based on the guideline proposed by Mathieu Poirier to keep as much as possible
the legacy implementation of the rpmsg_char used by the GLINK and SMD platforms.

Objectives of the series:
- Allow to create a service from Linux user application:
- with a specific name
- with or without name service announcement.
- Allow to probe the same service by receiving either a NS announcement from the remote firmware
or a Linux user application request.
- Use these services independently of the RPMsg transport implementation (e.g be able to use
RPMSg char with the RPMsg virtio bus).

Steps in the series:
- Extract the control part of the char dev and create the rpmsg_ctrl.c file (patches 1 to 6)
- Enable the use of the chardev with the virtio backend (patches 7 to 11)
- Introduce the RPMSG_CREATE_DEV_IOCTL IOCTL to instantiate RPMsg devices (patch 12)
The application can then create or release a channel by specifying:
- the name service of the device to instantiate.
- the source address.
- the destination address.
- Instantiate the /dev/rpmsg interface on remote NS announcement (patches 13 to 16)

In this revision, I do not divide the series into several parts in order to show a complete
picture of the proposed evolution. To simplify the review, if requested, I can send it in
several steps listed above.

Known current Limitations:
- Tested only with virtio RPMsg bus. The glink and smd drivers adaptations have not been tested
(not able to test it).
- For the virtio backend: No NS announcement is sent to the remote processor if the source
address is set to RPMSG_ADDR_ANY.
- For the virtio backend: the existing RPMSG_CREATE_EPT_IOCTL is working but the endpoints are
not attached to an exiting channel.
- to limit patches the pending RPMSG_DESTROY_DEV_IOCTL has not ben implemented. This will be
proposed in a second step.

This series can be applied on git/andersson/remoteproc.git for-next branch (d9ff3a5789cb).

This series can be tested using rpmsgexport, rpmsgcreatedev and ping tools available here:
https://github.com/arnopo/rpmsgexport.git

Reference to the V4 discussion thread: https://lkml.org/lkml/2021/2/17/384

Arnaud Pouliquen (16):
rpmsg: char: rename rpmsg_char_init to rpmsg_chrdev_init
rpmsg: move RPMSG_ADDR_ANY in user API
rpmsg: add short description of the IOCTL defined in UAPI.
rpmsg: char: export eptdev create an destroy functions
rpmsg: char: dissociate the control device from the rpmsg class
rpmsg: move the rpmsg control device from rpmsg_char to rpmsg_ctrl
rpmsg: update rpmsg_chrdev_register_device function
rpmsg: glink: add sendto and trysendto ops
rpmsg: smd: add sendto and trysendto ops
rpmsg: char: use sendto to specify the message destination address
rpmsg: virtio: register the rpmsg_ctrl device
rpmsg: ctrl: introduce RPMSG_CREATE_DEV_IOCTL
rpmsg: char: introduce __rpmsg_chrdev_create_eptdev function
rpmsg: char: introduce a RPMsg driver for the RPMsg char device
rpmsg: char: no dynamic endpoint management for the default one
rpmsg: char: return an error if device already open

drivers/rpmsg/Kconfig | 9 ++
drivers/rpmsg/Makefile | 1 +
drivers/rpmsg/qcom_glink_native.c | 18 ++-
drivers/rpmsg/qcom_smd.c | 18 ++-
drivers/rpmsg/rpmsg_char.c | 237 +++++++++++-------------------
drivers/rpmsg/rpmsg_char.h | 51 +++++++
drivers/rpmsg/rpmsg_ctrl.c | 229 +++++++++++++++++++++++++++++
drivers/rpmsg/rpmsg_internal.h | 10 +-
drivers/rpmsg/virtio_rpmsg_bus.c | 57 ++++++-
include/linux/rpmsg.h | 3 +-
include/uapi/linux/rpmsg.h | 18 ++-
11 files changed, 485 insertions(+), 166 deletions(-)
create mode 100644 drivers/rpmsg/rpmsg_char.h
create mode 100644 drivers/rpmsg/rpmsg_ctrl.c

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2.17.1