[PATCH v2 00/16] introduce generic IOCTL interface for RPMsg channels management

[Arnaud Pouliquen]

This series is a restructuring of the RPMsg char driver, to create a generic
RPMsg ioctl interface for all rpmsg services.

The RPMsg char driver provides interfaces that:
- expose a char RPMsg device for communication with the remote processor,
- expose controls interface for applications to create and release endpoints.

The objective of this series is to decorrelate the two interfaces:
  - Provide a char device for a RPMsg raw service in the rpmsg_char that can be
    probed by a RPMsg bus on a ns announcement.
  - Generalize the use of the ioctl for all RPMsg services by creating the
    rpmsg_ctrl, but keep it compatibile with the legacy.

If the V1 create a new rpmsg_raw driver in addition to the rpmsg_ctrl this
version try to reuse the rpmsg_char driver by addapting QCOM GLINK and SMD
drivers.
So a goal of this version is to help to determine the best strategy to move
forward:
  - reuse rpmsg_char.
  - introduce a new driver and keep rpmsg_char as a legacy driver for a while.

Notice that SMD and GLINK patches have to be tested, only build has been tested.

1) RPMsg control driver: rpmsg_ctrl.c
  This driver is based on the control part of the RPMsg_char driver. 
  On probe a /dev/rpmsg_ctrl<X> interface is created to allow to manage the
  channels.
  The principles are the following:
  - The RPMsg service driver registers it's name and the associated service
    using the rpmsg_ctrl_unregister_ctl API. The list of supported services
    is defined in  include/uapi/linux/rpmsg.h and exposed to the
    application thanks to a new field in rpmsg_endpoint_info struct.
  - On the RPMsg bus probe(e.g virtio bus) an rpmsg_ctrl device is
    registered that creates the control interface.
  - The application can then create or release a channel by specifying:
       - the name service
       - the source address.
       - the destination address.
  - The rpmsg_ctrl uses the same interface than the ns announcement to
    create and release the associated channel but using the driver_override
    field to force the service name.
    The  "driver_override" allows to force the name service associated to
    an RPMsg driver, bypassing the rpmsg_device_id based match check.
  - At least for virtio bus, an associated ns announcement is sent to the
    remote side.  

2) rpmsg char driver: rpmsg_char.c
    - The rpmsg class has not been removed. The associated attributes
      are already available in /sys/bus/rpmsg/.
    - The eptdev device is now an RPMsg device probed by a RPMsg bus driver
      (probed only by the ioctl in rpmsg_char driver).

Know current Limitations:
- Tested only with virtio RPMsg bus and for one vdev instance.
- The glink and smd drivers adaptations have not been tested (not able to test).
- To limit commit and not update the IOCT interface some features have been not
  implemented in this first step:
    - the NS announcement as not been updated, it is not possible to create an
      endpoint with a destibnation address set to RPMSG_ADDR_ANY (-1),
    - not possible to destroy the channel,
    - only the "rpmsg-raw" service is supported.

This series can be applied in Bjorn's rpmsg-next branch on top of the
RPMsg_ns series(4c0943255805).

This series can be tested using rpmsgexport tools available here:
https://github.com/andersson/rpmsgexport.
---
new from V1[1]:
- In V1 the rpmsg_char.c was not impacted, a rpmsg_raw.c has been created
  instead.
- IOCTL interface as not been updated (to go by steps).
- smd and glink drivers has been updated to support channels creation and
  release.

[1] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=327277

Arnaud Pouliquen (16):
  rpmsg: introduce RPMsg control driver for channel creation
  rpmsg: add RPMsg control API to register service
  rpmsg: add override field in channel info
  rpmsg: ctrl: implement the ioctl function to create device
  rpmsg: ns: initialize channel info override field
  rpmsg: add helper to register the rpmsg ctrl device
  rpmsg: char: clean up rpmsg class
  rpmsg: char: make char rpmsg a rpmsg device without the control part
  rpmsg: char: register RPMsg raw service to the ioctl interface.
  rpmsg: char: allow only one endpoint per device
  rpmsg: char: check destination address is not null
  rpmsg: virtio: use the driver_override in channel creation ops
  rpmsg: virtio: probe the rpmsg_ctl device
  rpmsg: glink: add create and release rpmsg channel ops
  rpmsg: smd: add create and release rpmsg channel ops
  rpmsg: replace rpmsg_chrdev_register_device use

 drivers/rpmsg/Kconfig             |   8 +
 drivers/rpmsg/Makefile            |   1 +
 drivers/rpmsg/qcom_glink_native.c |  96 +++++++--
 drivers/rpmsg/qcom_smd.c          |  59 +++++-
 drivers/rpmsg/rpmsg_char.c        | 246 ++++++-----------------
 drivers/rpmsg/rpmsg_ctrl.c        | 320 ++++++++++++++++++++++++++++++
 drivers/rpmsg/rpmsg_internal.h    |  14 --
 drivers/rpmsg/rpmsg_ns.c          |   1 +
 drivers/rpmsg/virtio_rpmsg_bus.c  |  38 +++-
 include/linux/rpmsg.h             |  40 ++++
 include/uapi/linux/rpmsg.h        |  14 ++
 11 files changed, 606 insertions(+), 231 deletions(-)
 create mode 100644 drivers/rpmsg/rpmsg_ctrl.c

-- 
2.17.1