[PATCH v4 00/16] introduce a generic IOCTL interface for RPMsg channels management

[Arnaud Pouliquen <arnaud.pouliquen@foss.st.com>]

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 fixes compilation issue reported by the kernel test robot <lkp@intel.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 5)
  - Enable the use of the chardev with the virtio backend (patches 6 to 10)
  - Introduce the RPMSG_CREATE_DEV_IOCTL IOCTL to instantiate RPMsg devices (patch 11)
    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 12 to 15)

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, as a next step, 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 V3 discussion thread: https://lkml.org/lkml/2021/2/4/194

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  |  37 ++++-
 include/linux/rpmsg.h             |   3 +-
 include/uapi/linux/rpmsg.h        |  18 ++-
 11 files changed, 469 insertions(+), 162 deletions(-)
 create mode 100644 drivers/rpmsg/rpmsg_char.h
 create mode 100644 drivers/rpmsg/rpmsg_ctrl.c

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2.17.1