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Fri, 01 Aug 2025 21:12:30 -0700 (PDT) Message-ID: <612a13d3-d3a6-460b-90fd-c26e47b80711@sifive.com> Date: Fri, 1 Aug 2025 23:12:28 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 02/24] dt-bindings: mailbox: Add bindings for RISC-V SBI MPXY extension To: Anup Patel Cc: Palmer Dabbelt , Paul Walmsley , Alexandre Ghiti , Len Brown , Sunil V L , Rahul Pathak , Leyfoon Tan , Atish Patra , Andrew Jones , Anup Patel , linux-clk@vger.kernel.org, devicetree@vger.kernel.org, linux-acpi@vger.kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Conor Dooley , Michael Turquette , Stephen Boyd , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Jassi Brar , Thomas Gleixner , "Rafael J . Wysocki" , Mika Westerberg , Andy Shevchenko , Linus Walleij , Bartosz Golaszewski , =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= References: <20250728094032.63545-1-apatel@ventanamicro.com> <20250728094032.63545-3-apatel@ventanamicro.com> From: Samuel Holland Content-Language: en-US In-Reply-To: <20250728094032.63545-3-apatel@ventanamicro.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Anup, On 2025-07-28 4:40 AM, Anup Patel wrote: > Add device tree bindings for the RISC-V SBI Message Proxy (MPXY) > extension as a mailbox controller. > > Reviewed-by: Conor Dooley > Signed-off-by: Anup Patel > --- > .../bindings/mailbox/riscv,sbi-mpxy-mbox.yaml | 51 +++++++++++++++++++ > 1 file changed, 51 insertions(+) > create mode 100644 Documentation/devicetree/bindings/mailbox/riscv,sbi-mpxy-mbox.yaml > > diff --git a/Documentation/devicetree/bindings/mailbox/riscv,sbi-mpxy-mbox.yaml b/Documentation/devicetree/bindings/mailbox/riscv,sbi-mpxy-mbox.yaml > new file mode 100644 > index 000000000000..061437a0b45a > --- /dev/null > +++ b/Documentation/devicetree/bindings/mailbox/riscv,sbi-mpxy-mbox.yaml > @@ -0,0 +1,51 @@ > +# 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 SBI Message Proxy (MPXY) extension based mailbox > + > +maintainers: > + - Anup Patel > + > +description: | > + The RISC-V SBI Message Proxy (MPXY) extension [1] allows supervisor > + software to send messages through the SBI implementation (M-mode > + firmware or HS-mode hypervisor). The underlying message protocol > + and message format used by the supervisor software could be some > + other standard protocol compatible with the SBI MPXY extension > + (such as RISC-V Platform Management Interface (RPMI) [2]). > + > + =========================================== > + References > + =========================================== > + > + [1] RISC-V Supervisor Binary Interface (SBI) v3.0 (or higher) > + https://github.com/riscv-non-isa/riscv-sbi-doc/releases > + > + [2] RISC-V Platform Management Interface (RPMI) v1.0 (or higher) > + https://github.com/riscv-non-isa/riscv-rpmi/releases > + > +properties: > + compatible: > + const: riscv,sbi-mpxy-mbox > + > + "#mbox-cells": > + const: 2 > + description: > + The first cell specifies channel_id of the SBI MPXY channel, > + the second cell specifies MSG_PROT_ID of the SBI MPXY channel What is the purpose of the second mailbox cell? The client can probe the message protocol using a SBI call, if it doesn't just assume a protocol based on the kind of node that references this mailbox. The SBI implementation knows the message protocol from the kind of node that instantiates the channel (for example riscv,rpmi-mpxy-clock has riscv,sbi-mpxy-channel-id). So this cell looks redundant. Regards, Samuel > + > +required: > + - compatible > + - "#mbox-cells" > + > +additionalProperties: false > + > +examples: > + - | > + mailbox { > + compatible = "riscv,sbi-mpxy-mbox"; > + #mbox-cells = <2>; > + };