Re: [PATCH] dt-bindings: interrupt-controller: riscv,cpu-intc: convert to dtschema

[Conor Dooley <conor@kernel.org>]

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Yo,

On Fri, May 17, 2024 at 08:37:40PM +0530, Kanak Shilledar wrote:
> Convert the RISC-V Hart-Level Interrupt Controller (HLIC) to newer
> DT schema, Created DT schema based on the .txt file which had
> `compatible`, `#interrupt-cells` and `interrupt-controller` as
> required properties.
> Changes made with respect to original file:
> - Changed the example to just use interrupt-controller instead of
> using the whole cpu block
> - Changed the example compatible string.
> 
> Signed-off-by: Kanak Shilledar <kanakshilledar111@protonmail.com>
> ---
>  .../interrupt-controller/riscv,cpu-intc.txt   | 52 -----------------
>  .../interrupt-controller/riscv,cpu-intc.yaml  | 57 +++++++++++++++++++
>  2 files changed, 57 insertions(+), 52 deletions(-)
>  delete mode 100644 Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt
>  create mode 100644 Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.yaml
> 
> diff --git a/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt b/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt
> deleted file mode 100644
> index 265b223cd978..000000000000
> --- a/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.txt
> +++ /dev/null
> @@ -1,52 +0,0 @@
> -RISC-V Hart-Level Interrupt Controller (HLIC)
> ----------------------------------------------
> -
> -RISC-V cores include Control Status Registers (CSRs) which are local to each
> -CPU core (HART in RISC-V terminology) and can be read or written by software.
> -Some of these CSRs are used to control local interrupts connected to the core.
> -Every interrupt is ultimately routed through a hart's HLIC before it
> -interrupts that hart.
> -
> -The RISC-V supervisor ISA manual specifies three interrupt sources that are
> -attached to every HLIC: software interrupts, the timer interrupt, and external
> -interrupts.  Software interrupts are used to send IPIs between cores.  The
> -timer interrupt comes from an architecturally mandated real-time timer that is
> -controlled via Supervisor Binary Interface (SBI) calls and CSR reads.  External
> -interrupts connect all other device interrupts to the HLIC, which are routed
> -via the platform-level interrupt controller (PLIC).
> -
> -All RISC-V systems that conform to the supervisor ISA specification are
> -required to have a HLIC with these three interrupt sources present.  Since the
> -interrupt map is defined by the ISA it's not listed in the HLIC's device tree
> -entry, though external interrupt controllers (like the PLIC, for example) will
> -need to define how their interrupts map to the relevant HLICs.  This means
> -a PLIC interrupt property will typically list the HLICs for all present HARTs
> -in the system.
> -
> -Required properties:
> -- compatible : "riscv,cpu-intc"

> -- #interrupt-cells : should be <1>.  The interrupt sources are defined by the
> -  RISC-V supervisor ISA manual, with only the following three interrupts being
> -  defined for supervisor mode:
> -    - Source 1 is the supervisor software interrupt, which can be sent by an SBI
> -      call and is reserved for use by software.
> -    - Source 5 is the supervisor timer interrupt, which can be configured by
> -      SBI calls and implements a one-shot timer.
> -    - Source 9 is the supervisor external interrupt, which chains to all other
> -      device interrupts.

I don't think that we should remove this test from the binding.

> -- interrupt-controller : Identifies the node as an interrupt controller
> -
> -Furthermore, this interrupt-controller MUST be embedded inside the cpu
> -definition of the hart whose CSRs control these local interrupts.
> -
> -An example device tree entry for a HLIC is show below.
> -
> -	cpu1: cpu@1 {
> -		compatible = "riscv";
> -		...
> -		cpu1-intc: interrupt-controller {
> -			#interrupt-cells = <1>;
> -			compatible = "sifive,fu540-c000-cpu-intc", "riscv,cpu-intc";
> -			interrupt-controller;
> -		};
> -	};
> diff --git a/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.yaml b/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.yaml
> new file mode 100644
> index 000000000000..6fe86d243633
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/interrupt-controller/riscv,cpu-intc.yaml
> @@ -0,0 +1,57 @@
> +# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/interrupt-controller/riscv,cpu-intc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: RISC-V Hart-Level Interrupt Controller (HLIC)
> +
> +description:
> +  RISC-V cores include Control Status Registers (CSRs) which are local to
> +  each CPU core (HART in RISC-V terminology) and can be read or written by
> +  software. Some of these CSRs are used to control local interrupts connected
> +  to the core. Every interrupt is ultimately routed through a hart's HLIC
> +  before it interrupts that hart.
> +
> +  The RISC-V supervisor ISA manual specifies three interrupt sources that are
> +  attached to every HLIC namely software interrupts, the timer interrupt, and
> +  external interrupts. Software interrupts are used to send IPIs between
> +  cores.  The timer interrupt comes from an architecturally mandated real-
> +  time timer that is controlled via Supervisor Binary Interface (SBI) calls
> +  and CSR reads. External interrupts connect all other device interrupts to
> +  the HLIC, which are routed via the platform-level interrupt controller
> +  (PLIC).
> +
> +  All RISC-V systems that conform to the supervisor ISA specification are
> +  required to have a HLIC with these three interrupt sources present.  Since
> +  the interrupt map is defined by the ISA it's not listed in the HLIC's device
> +  tree entry, though external interrupt controllers (like the PLIC, for
> +  example) will need to define how their interrupts map to the relevant HLICs.
> +  This means a PLIC interrupt property will typically list the HLICs for all
> +  present HARTs in the system.
> +

> +maintainers:
> +  - Kanak Shilledar <kanakshilledar111@protonmail.com>

Are you knowledgeable about the cpu-intc on RISC-V? If you put yourself
down just to satisfy dt_binding_check, I would suggest that you put down
Palmer and Paul here as the maintainers of the architecture instead.

> +properties:
> +  compatible:
> +    const: "riscv,cpu-intc"

A new warning with dtbs_check from your patch:
/stuff/linux/build/arch/riscv/boot/dts/renesas/r9a07g043f01-smarc.dtb: interrupt-controller: compatible:0: 'riscv,cpu-intc' was expected
	from schema $id: http://devicetree.org/schemas/interrupt-controller/riscv,cpu-intc.yaml#
/stuff/linux/build/arch/riscv/boot/dts/renesas/r9a07g043f01-smarc.dtb: interrupt-controller: compatible: ['andestech,cpu-intc', 'riscv,cpu-intc'] is too long
	from schema $id: http://devicetree.org/schemas/interrupt-controller/riscv,cpu-intc.yaml#

There's a duplicate description in riscv/cpus.yaml:
  interrupt-controller:
    type: object
    additionalProperties: false
    description: Describes the CPU's local interrupt controller

    properties:
      '#interrupt-cells':
        const: 1

      compatible:
        oneOf:
          - items:
              - const: andestech,cpu-intc
              - const: riscv,cpu-intc
          - const: riscv,cpu-intc

      interrupt-controller: true

I think the one in cpus.yaml should be converted to a ref and the
andestech compatible added here.

> +  interrupt-controller: true
> +
> +  '#interrupt-cells': true

`const: 1` to match the text binding being removed.

Cheers,
Conor.

> +
> +required:
> +  - compatible
> +  - '#interrupt-cells'
> +  - interrupt-controller
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    interrupt-controller {
> +        #interrupt-cells = <1>;
> +        compatible = "riscv,cpu-intc";
> +        interrupt-controller;
> +    };
> -- 
> 2.34.1
> 

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