[RFC PATCH v3 0/4] remoteproc: restructure the remoteproc VirtIO device

[Arnaud Pouliquen]

Update from V2 [1]:
In order to better handle error cases and to have something more symmetrical between
the functions in charge of rvdev initialization/deletion, the patchset has been reworked.
 - Introduction in the first patch, of rproc_vdev_data structure which allows to better
   decorrelate the rproc from the management of the rvdev structure. This structure is reused
   in the last patch of the series for the creation of the remoteproc virtio platform device.
 - In addition to the previous version, the management of the vring lifecycle has been fully
   migrated to the remoteproc_virtio.c (rproc_parse_vring, rproc_alloc_vring, rproc_free_vring)

[1] https://lkml.org/lkml/2021/12/22/111

Patchset description:

This series is a part of the work initiated a long time ago in 
the series "remoteproc: Decorelate virtio from core"[2]

Objective of the work:
- Update the remoteproc VirtIO device creation (use platform device)
- Allow to declare remoteproc VirtIO device in DT
    - declare resources associated to a remote proc VirtIO
    - declare a list of VirtIO supported by the platform.
- Prepare the enhancement to more VirtIO devices (e.g I2C, audio, video, ...).
  For instance be able to declare a I2C device in a virtio-i2C node.
- Keep the legacy working!
- Try to improve the picture about concerns reported by Christoph Hellwing [3][4]

[2] https://lkml.org/lkml/2020/4/16/1817
[3] https://lkml.org/lkml/2021/6/23/607
[4] https://patchwork.kernel.org/project/linux-remoteproc/patch/AOKowLclCbOCKxyiJ71WeNyuAAj2q8EUtxrXbyky5E@xxxxxxxxxxxxxxxxxxxx/

In term of device tree this would result in such hiearchy (stm32mp1 example with 2 virtio RPMSG):

	m4_rproc: m4@10000000 {
		compatible = "st,stm32mp1-m4";
		reg = <0x10000000 0x40000>,
		      <0x30000000 0x40000>,
		      <0x38000000 0x10000>;
        memory-region = <&retram>, <&mcuram>,<&mcuram2>;
        mboxes = <&ipcc 2>, <&ipcc 3>;
        mbox-names = "shutdown", "detach";
        status = "okay";

        #address-cells = <1>;
        #size-cells = <0>;
        
        vdev@0 {
		compatible = "rproc-virtio";
		reg = <0>;
		virtio,id = <7>;  /* RPMSG */
		memory-region = <&vdev0vring0>, <&vdev0vring1>, <&vdev0buffer>;
		mboxes = <&ipcc 0>, <&ipcc 1>;
		mbox-names = "vq0", "vq1";
		status = "okay";
        };

        vdev@1 {
		compatible = "rproc-virtio";
		reg = <1>;
		virtio,id = <7>;  /*RPMSG */
		memory-region = <&vdev1vring0>, <&vdev1vring1>, <&vdev1buffer>;
		mboxes = <&ipcc 4>, <&ipcc 5>;
		mbox-names = "vq0", "vq1";
		status = "okay";
        };
};

I have divided the work in 4 steps to simplify the review, This series implements only
the step 1:
step 1:  redefine the remoteproc VirtIO device as a platform device
  - migrate rvdev management in remoteproc virtio.c,
  - create a remotproc virtio config ( can be disabled for platform that not use VirtIO IPC.
step 2: add possibility to declare and prob a VirtIO sub node
  - VirtIO bindings declaration,
  - multi DT VirtIO devices support,
  - introduction of a remote proc virtio bind device mechanism ,
=> https://github.com/arnopo/linux/commits/step2-virtio-in-DT
step 3: Add memory declaration in VirtIO subnode
=> https://github.com/arnopo/linux/commits/step3-virtio-memories
step 4: Add mailbox declaration in VirtIO subnode
=> https://github.com/arnopo/linux/commits/step4-virtio-mailboxes

Arnaud Pouliquen (4):
  remoteproc: core: Introduce virtio device add/remove functions
  remoteproc: core: Introduce rproc_register_rvdev function
  remoteproc: Move rproc_vdev management to remoteproc_virtio.c
  remoteproc: virtio: Create platform device for the remoteproc_virtio

 drivers/remoteproc/remoteproc_core.c     | 159 +++----------------
 drivers/remoteproc/remoteproc_internal.h |  33 +++-
 drivers/remoteproc/remoteproc_virtio.c   | 193 ++++++++++++++++++++---
 include/linux/remoteproc.h               |   6 +-
 4 files changed, 227 insertions(+), 164 deletions(-)

-- 
2.25.1