Adding a new platform: renesas rz

[Michele Bisogno]

Torsten,

> The question then is: are they similar enough to build from one kernel
> source, or will they require different sets of patches?

RZ includes different subseries, as of today: RZ/G, RZ/V and some new
RZ/T run Linux.
Renesas official SW package is based on the CIP Linux, even though the
support of the devices is regularly upstreamed in the Linux kernel.
I kind of know that the maintainers are trying to keep things
consistent and usually the same kernel image works for all the
supported devices, requiring just a different device tree.
My idea at the moment is to add the devices that are supported in Linux 6.1.


> Have you looked at the peripherials on the SoCs? Is RZ/Five identical
> to RZ/Arm in that respect? I've seen this at WinChipHead, for
> microcontrollers. The reasoning again would be whether it could be
> built from the same source code base.

RZ/Five is basically a RZ/G2UL with a RISC-V CPU instead of Arm.
Of course for RZ/Five the same kernel binary cannot work.
On top of that, it's a pity that the RZ/Five started to be supported
from 6.2, I'm not sure what to do with it.

> If not, how about "rzarm", leaving room for future "rzfive"? I know this
> sounds like bike shedding, but it might actually save some renaming
> work in the future. Naming it just "renesas" does not feel right, IMHO.

Honestly I am fine with any naming, that's why I am here asking and
discussing it.

Kind regards,
Michele

On Fri, 3 Nov 2023 at 09:04, Michele Bisogno <micbis.openwrt at gmail.com> wrote:
>
> > Renesas offers different architectures in their portfolio[1], I haven't
> > dug into the OpenWRT build system for this issue yet to tell whether it
> > is able to handle that at this folder level. Much of the above is
> > "legacy" and does not run OpenWRT(?), but they also seem to aim for
> > Risc-V. There is a platform called "ramips" and the broadcoms each have
> > their own subdirectory. None of them have punctuation yet. Maybe call it
> > "renesasrz"? They're also offering other ARM-based SoCs, and building
> > common kernels might become difficult.
> > Torsten
> > [1] https://www.renesas.com/eu/en/products/microcontrollers-microprocessors/other-mcus-mpus
>
> Hi Torsten,
>
> what is listed there is old stuff. Renesas MPUs are now all under the
> RZ umbrella.
> Well, actually there are also the rcar devices, but these are automotive SoCs.
> Yes, there is an RZ device that is not Arm: RZ/Five. For now it is a
> single device based on a Andes core.
>
> Kind regards,
> Michele