[PATCH 0/8] Make SCMI transport as standalone drivers

[Florian Fainelli]

On 7/10/24 10:31, 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 [1/8] is a mostly unrelated (but much needed) clean-up from Peng,
> which I included in this series to avoid conflicts at merge.
> 
> Patch [2/8] simply collects the existing datagram manipulation helpers in a
> pair of function pointers structures, in preparation for later reworks.
> 
> Patch [3/8] 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 4,5,6,7 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 [8/8] 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)
> 
> 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 ]
> 
> ToBeDone:
>   - completely remove any dependency at build time at the Kconfig level between
>     the SCMI core and the transport drivers: so that the transports will be
>     dependent only on the related subsystems (optee/virtio/mailbox/smc)
>     (easy to be done but maybe it is not worth...)
>   - integrate per-platform transport configuration capabilities
>     (max_rx_timeout_ms & friends..)
> 
> Based on sudeep/for-next/scmi/updates.
> 
> Any feedback, and especially testing (:D) is welcome.

Tested-by: Florian Fainelli <florian.fainelli at broadcom.com>
-- 
Florian