[PATCH v2 0/1] rpmsg: ctrl: Add ability to instantiate rpmsg device locally

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

Purpose:
  Allow the user space application to create and release an rpmsg device by adding
  rpmsg ioctrl to the /dev/rpmsg_ctrl interface
    
Aim:
  The current implementation is based on the enumeration of services by the 
  remote processor to create a new channel and instantiate associated rpmsg device.
  There is no solution to create a rpmsg channel on user application request.
  If the rpmsg char driver allows adding a new endpoint over an existing channel, it
  does not offer the ability to create a new one.
  Adding the IOCTRL to instantiate rpmsg channels from the user application will allow
  to dynamically create and destroy rpmsg devices. Some examples of use are:
  - activate the service at the initiative of the application,
  - remove the communication on a specific channel before entering the suspend mode,
  - creating a temporary channel for debugging purposes.


Delta vs V1 [1]
- Squah patches 1/4(rpmsg: ctrl: Introduce RPMSG_CREATE_DEV_IOCTL) and
  2/4 (rpmsg: ctrl: Introduce RPMSG_RELEASE_DEV_IOCTL).
- Remove the rpmsg device attribue to check if a rpmg device can be released, choose to trust
  the application (a similar trust already exists for the bind/unbind interface).

[1] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=494021

How to test it:
  - This series can be applied on git/andersson/remoteproc.git for-next branch (dc0e14fa833b)
    + the "Restructure the rpmsg char to decorrelate the control part" series[2]
  - to test the ioctrl, a rpmsgexportdev tool is available here:
     https://github.com/arnopo/rpmsgexport

[2]https://patchwork.kernel.org/project/linux-remoteproc/list/?series=483793

Arnaud Pouliquen (1):
  rpmsg: ctrl: Introduce new RPMSG_CREATE/RELEASE_DEV_IOCTL controls

 drivers/rpmsg/rpmsg_ctrl.c | 37 +++++++++++++++++++++++++++++++++----
 include/uapi/linux/rpmsg.h | 10 ++++++++++
 2 files changed, 43 insertions(+), 4 deletions(-)

-- 
2.17.1