Re: [RFC PATCH v3 25/35] Documentation/devicetree/bindings/sh/cpus.yaml: Add SH CPU.

Hi Jeff,

On Wed, Oct 25, 2023 at 1:33 PM D. Jeff Dionne <[email protected]> wrote:
> > On Oct 25, 2023, at 20:14, Yoshinori Sato <[email protected]> wrote:
> > On Wed, 18 Oct 2023 23:27:43 +0900,
> > Geert Uytterhoeven wrote:
> >> On Sat, Oct 14, 2023 at 4:54 PM Yoshinori Sato
> >> <[email protected]> wrote:
> >>> Renesas SuperH binding definition.
> >>>
> >>> Signed-off-by: Yoshinori Sato <[email protected]>

> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/sh/cpus.yaml
> >>> @@ -0,0 +1,45 @@
> >>> +# SPDX-License-Identifier: GPL-2.0
> >>> +%YAML 1.2
> >>> +---
> >>> +$id: http://devicetree.org/schemas/sh/cpus.yaml#
> >>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >>> +
> >>> +title: Renesas SuperH CPUs
> >>> +
> >>> +maintainers:
> >>> +  - Yoshinori Sato <[email protected]>
> >>> +
> >>> +description: |+
> >>> +  The device tree allows to describe the layout of CPUs in a system through
> >>> +  the "cpus" node, which in turn contains a number of subnodes (ie "cpu")
> >>> +  defining properties for every cpu.
> >>> +
> >>> +  Bindings for CPU nodes follow the Devicetree Specification, available from:
> >>> +
> >>> +  https://www.devicetree.org/specifications/
> >>> +
> >>> +properties:
> >>> +  compatible:
> >>> +    items:
> >>> +      - enum:
> >>
> >> Missing
> >>
> >>    - jcore,j2

> We must not imply that Renesas is responsible for J2, or that it is a sanctioned SH core.

Compatible values do not declare any such endorsement.

> J-Core has the responsibility for maintenance of those SH ISA compatible cores.

The question is: does J2 implement the same instruction set as SH2,
i.e. can it run unmodified SH2 code?

> >>
> >>> +          - renesas,sh4
> >>
> >>
> >>> +      - const: renesas,sh
> >>
> >> I see arch/sh/boot/dts/j2_mimas_v2.dts lacks the fallback to
> >> "renesas,sh", though.
> >> Is there a common base of instructions that are available on all SH cores?
> >
> > The base instruction set is sh2.
> > Before that, there is sh1, but this is not compatible with Linux.
> > I think it would be a good idea to change this to "renesas,sh2",

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds