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

Arnaud Pouliquen
2020-12-22T11:00:08Z

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

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2.17.1