Re: [PATCH v3 0/9] Make SCMI transport as standalone drivers

[Nikunj Kela <quic_nkela@quicinc.com>]

On 7/30/2024 6:33 AM, Cristian Marussi wrote:
> Hi all,
>
> Till now the SCMI transport layer was being built embedded into in the core
> SCMI stack.
>
> Some of these transports, despite being currently part of the main SCMI
> module, are indeed also registered with different subsystems like optee or
> virtio, and actively probed also by those: this led to a few awkward and
> convoluted tricks to properly handle such interactions at boot time in the
> SCMI stack.
>
> Moreover some partner expressed the desire to be able to fully modularize
> the transports components.
>
> This series aim to make all such transports as standalone drivers that can
> be optionally loaded as modules.
>
> In order to do this, at first some new mechanism is introduced to support
> this new capability while maintaining, in parallel, the old legacy embedded
> transports; then each transport, one by one, is transitioned to be a
> standalone driver and finally the old legacy support for embedded transport
> is removed.
>
> Patch [1/9] is a fix around the chan_free method for OPTEE transport; it is
> really unrelated to this series, but included to avoid conflicts.
>
> Patch [2/9] is a mostly unrelated (but much needed) clean-up from Peng,
> which I included in this series to avoid conflicts at merge.
>
> Patch [3/9] simply collects the existing datagram manipulation helpers in a
> pair of function pointers structures, in preparation for later reworks.
>
> Patch [4/9] adds the bulk of the new logic to the core SCMI stack and then
> each existing transport is transitioned to be a standalone driver in
> patches 5,6,7,8 while shuffling around the compatibles. (no DT change is
> needed of curse for backward compatibility)
> While doing this I kept the module authorship in line with the main
> author(S) as spitted out by git-blame.
>
> Finally patch [9/9] removes all the legacy dead code from the core SCMI
> stack.
>
> No new symbol EXPORT has been added.
>
> The new transport drivers have been tested, as built-in and LKM, as
> follows:
>
> - mailbox on JUNO
> - virtio on emulation
> - optee on QEMU/optee using Linaro setup
>
> Exercised using the regular SCMI drivers stack and the SCMI ACS suite,
> testing commands, replies, delayed responses and notification.
>
> Multiple virtual SCMI instances support has been tested too.
>
> SMC has NOT been tested/exercised at run-time, only compile-tested.
> (due to lack of hardware)

Hi Christian,

I have validated this series on Qualcomm SA8255p(to be upstreamed) Ride
platform that uses Qualcomm SMC transport for SCMI.

Thanks,

-Nikunj

> Note that in this new setup, all the probe deferral and retries between the
> SCMI core stack and the transports has been removed, since no more needed.
>
> Moreover the new drivers have been tested also with a fully modularized
> SCMI stack, i.e.:
>
>   scmi-core.ko + scmi-module.ko + scmi_transport_*.ko [ + vendor modules ]
>
> Based on v6.11-rc1
>
> Any feedback, and especially testing (:D) is welcome.
>
> Thanks,
> Cristian
>
> ---
> v2 --> v3
> - rebased on v6.11-rc1
> - fixed spacing in Kconfig
> - fixed Copyrights all over
> - fixed platform_driver_register callsite in OPTEE transport
> - refactored DEFINE_SCMI_TRANSPORT_DRIVER() to:
>   + use alloc + add_data + add platform drivers methods so as to implictly
>     use a standard default device_release method.
>   + drop .remove method in favour of devres_add_action_or_reset
>   + use explicit parameter passing (no more concatenation)
> - renamed scmi_transport_lookup() to scmi_transport_setup()
> - use IOMEM_ERR_PTR to avoid sparse issues
>
> v1 --> v2
> - fixed setup_shmem_iomap to address also SMC needs (QC/nikunj)
>   (silencing also warnings by kernel test robot <lkp@intel.com>)
> - using __free OF cleanup.h magic in setup_shmme_iomap
> - properly handle platform_driver_register() failures (Dan)
> - fixed a few commit message style
> - added a few missing static in scmi_desc
>   (addresses warnings by kernel test robot <lkp@intel.com>)
>
>
> Cristian Marussi (8):
>   firmware: arm_scmi: Fix double free in OPTEE transport
>   firmware: arm_scmi: Introduce packet handling helpers
>   firmware: arm_scmi: Add support for standalone transport drivers
>   firmware: arm_scmi: Make MBOX transport a standalone driver
>   firmware: arm_scmi: Make SMC transport a standalone driver
>   firmware: arm_scmi: Make OPTEE transport a standalone driver
>   firmware: arm_scmi: Make VirtIO transport a standalone driver
>   firmware: arm_scmi: Remove legacy transport-layer code
>
> Peng Fan (1):
>   firmware: arm_scmi: Introduce setup_shmem_iomap
>
>  drivers/firmware/arm_scmi/Kconfig             |  20 +-
>  drivers/firmware/arm_scmi/Makefile            |   9 +-
>  drivers/firmware/arm_scmi/common.h            | 184 +++++++++++++-----
>  drivers/firmware/arm_scmi/driver.c            | 142 +++++---------
>  drivers/firmware/arm_scmi/msg.c               |  32 ++-
>  .../{mailbox.c => scmi_transport_mailbox.c}   |  72 +++----
>  .../{optee.c => scmi_transport_optee.c}       | 130 ++++++-------
>  .../arm_scmi/{smc.c => scmi_transport_smc.c}  |  57 +++---
>  .../{virtio.c => scmi_transport_virtio.c}     | 102 +++++-----
>  drivers/firmware/arm_scmi/shmem.c             |  85 ++++++--
>  10 files changed, 477 insertions(+), 356 deletions(-)
>  rename drivers/firmware/arm_scmi/{mailbox.c => scmi_transport_mailbox.c} (86%)
>  rename drivers/firmware/arm_scmi/{optee.c => scmi_transport_optee.c} (89%)
>  rename drivers/firmware/arm_scmi/{smc.c => scmi_transport_smc.c} (87%)
>  rename drivers/firmware/arm_scmi/{virtio.c => scmi_transport_virtio.c} (94%)
>