Re: [PATCH 0/4] rpmsg: char: introduce the rpmsg-raw channel

Mathieu Poirier
2021-06-08T14:27:39Z

Hi Arnaud,

Between remoteproc/RPMSG and CoreSight, I have 6 patchsets to review
(including some of your work) before getting to this one. As such it
will take a little while.

Thanks,
Mathieu

On Mon, 7 Jun 2021 at 11:30, Arnaud Pouliquen
<arnaud.pouliquen@foss.st.com> wrote:
>
> Purpose:
> Allow the remote processor to instantiate a /dev/rpmsgX interface relying on the NS announcement
> of the "rpmsg-raw" service.
> This patchet is extracted from the series [1] with rework to add rpmsg_create_default_ept helper.
>
>
> Aim:
> There is no generic sysfs interface based on RPMsg that allows a user application to communicate
> with a remote processor in a simple way.
> The rpmsg_char dev solves a part of this problem by allowing an endpoint to be created on the
> local side. But it does not take advantage of the NS announcement mechanism implemented for some
> backends such as the virtio backend. So it is not possible to probe it from a remote initiative.
> Extending the char rpmsg device to support NS announcement makes the rpmsg_char more generic.
> By announcing a "rpmg-raw" service, the firmware of a remote processor will be able to
> instantiate a /dev/rpmsgX interface providing to the user application a basic link to communicate
> with it without any knowledge of the rpmsg protocol.
>
> Implementation details:
> - Register a rpmsg driver for the rpmsg_char driver, associated to the "rpmsg-raw" channel service.
> - In case of rpmsg char device instantiated by the rpmsg bus (on NS announcement) manage the
> channel default endpoint to ensure a stable default endpoint address, for communication with
> the remote processor.
>
> 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]
>
> [1] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=475217
> [2] https://patchwork.kernel.org/project/linux-remoteproc/list/?series=483793
>
>
>
> Arnaud Pouliquen (4):
> rpmsg: Introduce rpmsg_create_default_ept function
> rpmsg: char: Add possibility to create and reuse default endpoint
> rpmsg: char: Introduce the "rpmsg-raw" channel
> rpmsg: char: Return error if user tries to destroy a default endpoint.
>
> drivers/rpmsg/rpmsg_char.c | 92 +++++++++++++++++++++++++++++++++++---
> drivers/rpmsg/rpmsg_core.c | 51 +++++++++++++++++++++
> include/linux/rpmsg.h | 14 ++++++
> 3 files changed, 151 insertions(+), 6 deletions(-)
>
> --
> 2.17.1
>