linux-kernel - Re: [RFC PATCH v2 08/17] dt-bindings: clock: Add bindings for RISC-V RPMI clock service group

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Message-ID: <CAK9=C2WKjDUGc5Se1nG=XTp3wn5ZytUcnghO_u85bSoqGiwmvA@mail.gmail.com>
Date: Sun, 4 May 2025 16:00:43 +0530
From: Anup Patel <apatel@...tanamicro.com>
To: Rob Herring <robh@...nel.org>
Cc: Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jassi Brar <jassisinghbrar@...il.com>, Thomas Gleixner <tglx@...utronix.de>, 
	"Rafael J . Wysocki" <rafael@...nel.org>, Mika Westerberg <mika.westerberg@...ux.intel.com>, 
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski <brgl@...ev.pl>, 
	Uwe Kleine-König <ukleinek@...nel.org>, 
	Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Len Brown <lenb@...nel.org>, Sunil V L <sunilvl@...tanamicro.com>, 
	Rahul Pathak <rpathak@...tanamicro.com>, Leyfoon Tan <leyfoon.tan@...rfivetech.com>, 
	Atish Patra <atishp@...shpatra.org>, Andrew Jones <ajones@...tanamicro.com>, 
	Samuel Holland <samuel.holland@...ive.com>, Anup Patel <anup@...infault.org>, 
	linux-clk@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 08/17] dt-bindings: clock: Add bindings for RISC-V
 RPMI clock service group

On Tue, Feb 4, 2025 at 4:21 AM Rob Herring <robh@...nel.org> wrote:
>
> On Mon, Feb 03, 2025 at 02:18:57PM +0530, Anup Patel wrote:
> > Add device tree bindings for the clock service group defined by the
> > RISC-V platform management interface (RPMI) specification.
> >
> > Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> > ---
> >  .../bindings/clock/riscv,rpmi-clock.yaml      | 77 +++++++++++++++++++
> >  1 file changed, 77 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/clock/riscv,rpmi-clock.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/clock/riscv,rpmi-clock.yaml b/Documentation/devicetree/bindings/clock/riscv,rpmi-clock.yaml
> > new file mode 100644
> > index 000000000000..c08491c04926
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/riscv,rpmi-clock.yaml
> > @@ -0,0 +1,77 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/clock/riscv,rpmi-clock.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: RISC-V RPMI clock service group based clock controller
> > +
> > +maintainers:
> > +  - Anup Patel <anup@...infault.org>
> > +
> > +description: |
> > +  The RISC-V Platform Management Interface (RPMI) [1] defines a
> > +  messaging protocol which is modular and extensible. The supervisor
> > +  software can send/receive RPMI messages via SBI MPXY extension [2]
> > +  or some dedicated supervisor-mode RPMI transport.
> > +
> > +  The RPMI specification [1] defines clock service group for accessing
> > +  system clocks managed by a platform microcontroller.
> > +
> > +  ===========================================
> > +  References
> > +  ===========================================
> > +
> > +  [1] RISC-V Platform Management Interface (RPMI)
> > +      https://github.com/riscv-non-isa/riscv-rpmi/releases
> > +
> > +  [2] RISC-V Supervisor Binary Interface (SBI)
> > +      https://github.com/riscv-non-isa/riscv-sbi-doc/releases
> > +
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - description:
> > +          Intended for use by the SBI implementation in machine mode or
> > +          software in supervisor mode.
> > +        const: riscv,rpmi-clock
> > +
> > +      - description:
> > +          Intended for use by the SBI implementation in machine mode.
> > +        const: riscv,rpmi-mpxy-clock
> > +
> > +  mboxes:
> > +    maxItems: 1
> > +    description:
> > +      Mailbox channel of the underlying RPMI transport or SBI message proxy.
> > +
> > +  riscv,sbi-mpxy-channel-id:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description:
> > +      The SBI MPXY channel id to be used for providing RPMI access to
> > +      the supervisor software. This property is mandatory when using
> > +      riscv,rpmi-mpxy-clock compatible string.
>
> That constraint can be expressed as:
>
> dependentSchemas:
>   riscv,sbi-mpxy-channel-id:
>     properties:
>       compatible:
>         const: riscv,rpmi-mpxy-clock
>
> Please double check that works.
>
> > +
> > +  "#clock-cells":
> > +    const: 1
> > +    description:
> > +      This property is mandatory when using riscv,rpmi-clock compatible string.
>
> Similar constraint here.
>
> Though the only thing the 2 compatibles have in common is 'mboxes'. I
> think it would be better to just split this into 2 docs.

Yes, it is much simpler to have 2 separate docs. I will update
in the next revision.

Regards,
Anup

>
> > +
> > +required:
> > +  - compatible
> > +  - mboxes
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    mpxy_mbox: sbi-mpxy-mbox {
>
> mailbox {
>
> > +          compatible = "riscv,sbi-mpxy-mbox";
> > +          #mbox-cells = <2>;
> > +    };
> > +    rpmi-clk {
>
> clock-controller {
>
> > +        compatible = "riscv,rpmi-clock";
> > +        mboxes = <&mpxy_mbox 0x1000 0x0>;
> > +        #clock-cells = <1>;
> > +    };
> > +...
> > --
> > 2.43.0
> >