Re: [PATCH 1/3] i3c: master: Rework SVC I3C to support vendor glue layers

[Frank Li]

On Wed, Oct 21, 2026 at 10:56:19AM +0800, Junyi Zhao wrote:
> Hi Frank,
>
> Thanks for looking at this.
>
> Amlogic A9 used the same SVC I3C IP engine, but the integration of it
> differs in the resources *around* the controller, which cannot be
> expressed as another quirks entry:
>
> - On the "ao" instance the bus clock is generated by an internal
>   divider (I3C_AO_FCLK_DIV_CTRL @0x304) programmed directly by the
>   driver; there is no CCF clock to clk_set_rate() on, while the
>   common probe assumes the fclk is a plain enable-able clock.

If it is in I3C memory region, you can do that by use callback. otherwise
should go through clock framework.

>
> - Amlogic added register blocks outside the Silvaco map: a
>   DMA bridge and a bus monitor (0x200..0x22c).

Does DMA bridge only for I3C? It should be go through standard DMA engine.

what bus monitor use for.

>   Enabling the DMA bridge later will need hooks in the common
>   transfer path.

We also need support DMA in future.

>
> Adding A9 support to svc-i3c-master.c directly, would make these
> becomes if-branches in probe()/PM/transfer paths of the shared
> driver, and the next vendor repeats that.

You can use callback function in drvdata.

> With the glue layer,
> i3c-main.c keeps today's logic unchanged: i3c-silvaco.c is the
> current probe code moved as-is (rename with 79% similarity), so
> blame/history is preserved.
>
> If the file move is the main concern, I can keep
> svc-i3c-master.c where it is and only export the alloc/probe/remove/PM/
> interface for glue drivers -- the essential part for me is keeping
> the resource handling out of the common code paths.

Now, there are not much user yet. Rename or re-org only when it becomes
complex enough.

Frank

>
> Also, per Neil's suggestion I'll try modeling the AO divider as a
> CCF clock in v2, which should drop one hook.
>
> Thanks,
> Junyi
>
>
> On 2026/10/20 4:32, Frank Li wrote:
> > [ EXTERNAL EMAIL ]
> >
> > On Mon, Oct 19, 2026 at 01:34:26PM +0800, Junyi Zhao via B4 Relay wrote:
> > > [You don't often get email from devnull+junyi.zhao.amlogic.com@xxxxxxxxxx. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> > >
> > > From: Junyi Zhao <junyi.zhao@xxxxxxxxxxx>
> > >
> > > The SVC I3C controller IP can be integrated into SoCs from different
> > > vendors. Peripheral resources associated with the controller, such as
> > > clocks, may vary between vendor implementations.
> > >
> > > Rework the driver to separate common functionality from
> > > vendor-specific extensions. The common logic is shared across all
> > > implementations, while platform-dependent operations are provided
> > > through vendor-specific hooks.
> > >
> > > Also add a corresponding MAINTAINERS entry for the SILVACO I3C
> > > controller.
> > >
> > > Signed-off-by: Junyi Zhao <junyi.zhao@xxxxxxxxxxx>
> > > ---
> >
> > No big difference. Needn't rework svc-i3c-master.c, you can add amlogic at
> > svc-i3c-master.c directly.
> >
> > Frank