linux-kernel - Re: [RFC PATCH 2/8] dt-bindings: mailbox: Add bindings for RPMI shared memory transport

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Message-ID: <CAK9=C2UtxKm_38SVzUZoe_OSqcU5Q6k87cZvGyPTozkVR8YoFQ@mail.gmail.com>
Date: Tue, 17 Dec 2024 09:49:36 +0530
From: Anup Patel <apatel@...tanamicro.com>
To: Conor Dooley <conor@...nel.org>
Cc: Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Jassi Brar <jassisinghbrar@...il.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Paul Walmsley <paul.walmsley@...ive.com>, 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>, 
	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 2/8] dt-bindings: mailbox: Add bindings for RPMI
 shared memory transport

On Tue, Dec 17, 2024 at 12:19 AM Conor Dooley <conor@...nel.org> wrote:
>
> On Mon, Dec 16, 2024 at 02:18:11PM +0530, Anup Patel wrote:
> > Add device tree bindings for the common RISC-V Platform Management
> > Interface (RPMI) shared memory transport as a mailbox controller.
> >
> > Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> > ---
> >  .../mailbox/riscv,rpmi-shmem-mbox.yaml        | 135 ++++++++++++++++++
> >  1 file changed, 135 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/mailbox/riscv,rpmi-shmem-mbox.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/mailbox/riscv,rpmi-shmem-mbox.yaml b/Documentation/devicetree/bindings/mailbox/riscv,rpmi-shmem-mbox.yaml
> > new file mode 100644
> > index 000000000000..8d713ba7ffc7
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mailbox/riscv,rpmi-shmem-mbox.yaml
> > @@ -0,0 +1,135 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/mailbox/riscv,sbi-mpxy-mbox.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: RISC-V Platform Management Interface (RPMI) shared memory mailbox
> > +
> > +maintainers:
> > +  - Anup Patel <anup@...infault.org>
> > +
> > +description: |
> > +  The RISC-V Platform Management Interface (RPMI) [1] defines a common shared
> > +  memory based RPMI transport. This RPMI shared memory transport integrates as
> > +  mailbox controller in the SBI implementation or supervisor software whereas
> > +  each RPMI service group is mailbox client in the SBI implementation and
> > +  supervisor software.
> > +
> > +  ===========================================
> > +  References
> > +  ===========================================
> > +
> > +  [1] RISC-V Platform Management Interface (RPMI)
> > +      https://github.com/riscv-non-isa/riscv-rpmi/releases
> > +
> > +properties:
> > +  compatible:
> > +    const: riscv,rpmi-shmem-mbox
> > +
> > +  reg:
> > +    oneOf:
> > +      - items:
> > +        - description: A2P request queue base address
> > +        - description: P2A acknowledgment queue base address
> > +        - description: P2A request queue base address
> > +        - description: A2P acknowledgment queue base address
> > +        - description: A2P doorbell address
> > +      - items:
> > +        - description: A2P request queue base address
> > +        - description: P2A acknowledgment queue base address
> > +        - description: A2P doorbell address
> > +
> > +  reg-names:
> > +    oneOf:
> > +      - items:
> > +        - const: a2p-req
> > +        - const: p2a-ack
> > +        - const: p2a-req
> > +        - const: a2p-ack
> > +        - const: db-reg
> > +      - items:
> > +        - const: a2p-req
> > +        - const: p2a-ack
> > +        - const: db-reg
> > +
> > +  interrupts:
> > +    minItems: 1
> > +    maxItems: 1
> > +    description:
> > +      The RPMI shared memory transport supports wired interrupt specified by
> > +      this property as the P2A doorbell.
> > +
> > +  msi-parent:
> > +    description:
> > +      The RPMI shared memory transport supports MSI as P2A doorbell and this
> > +      property specifies the target MSI controller.
> > +
> > +  riscv,slot-size:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    minimum: 64
> > +    description:
> > +      Power-of-2 RPMI slot size of the RPMI shared memory transport.
> > +
> > +  riscv,db-mask:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description:
> > +      Update only the register bits of doorbell defined by the mask (32 bit).
>
> For an untested RFC, the bindings here look mostly fine. I'd suggest
> renaming "db" to "doorbell" in properties etc, since we can easily
> afford the extra characters. Please make sure to actually test the
> bindings next time around, looks like all 3 bindings produced warnings.

Okay, I will fix these issues in the next revision.

>
> General comments like not needing to provide minItems: 1 when maxItems
> is also 1, and not needing a | unless you have formatting to preserve.

Okay, I will update.

>
> > +      If this property is not present then mask is assumed to be 0xffffffff.
>
> Also, things like this should be handled with a `default: 0xffffffff`,
> rather than describing it in text.

Okay, I will update.

>
> I'll give the !rfc bindings a proper review when they appear, but before
> that I'll give the code here a go too - thanks for sending the patches.
>
> Cheers,
> Conor.

Regards,
Anup