Re: [PATCH v1 2/3] dt-bindings: riscv: convert plic bindings to json-schema

[Rob Herring <robh@kernel.org>]

On Thu, Sep 10, 2020 at 04:14:03PM +0530, Sagar Kadam wrote:
> Convert device tree bindings for SiFive's PLIC to YAML format
> 
> Signed-off-by: Sagar Kadam <sagar.kadam@sifive.com>
> ---
>  .../interrupt-controller/sifive,plic-1.0.0.txt     |  58 -----------
>  .../interrupt-controller/sifive,plic-1.0.0.yaml    | 107 +++++++++++++++++++++
>  2 files changed, 107 insertions(+), 58 deletions(-)
>  delete mode 100644 Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.txt
>  create mode 100644 Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml
> 
> diff --git a/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.txt b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.txt
> deleted file mode 100644
> index 6adf7a6..0000000
> --- a/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.txt
> +++ /dev/null
> @@ -1,58 +0,0 @@
> -SiFive Platform-Level Interrupt Controller (PLIC)
> --------------------------------------------------
> -
> -SiFive SOCs include an implementation of the Platform-Level Interrupt Controller
> -(PLIC) high-level specification in the RISC-V Privileged Architecture
> -specification.  The PLIC connects all external interrupts in the system to all
> -hart contexts in the system, via the external interrupt source in each hart.
> -
> -A hart context is a privilege mode in a hardware execution thread.  For example,
> -in an 4 core system with 2-way SMT, you have 8 harts and probably at least two
> -privilege modes per hart; machine mode and supervisor mode.
> -
> -Each interrupt can be enabled on per-context basis.  Any context can claim
> -a pending enabled interrupt and then release it once it has been handled.
> -
> -Each interrupt has a configurable priority.  Higher priority interrupts are
> -serviced first.  Each context can specify a priority threshold. Interrupts
> -with priority below this threshold will not cause the PLIC to raise its
> -interrupt line leading to the context.
> -
> -While the PLIC supports both edge-triggered and level-triggered interrupts,
> -interrupt handlers are oblivious to this distinction and therefore it is not
> -specified in the PLIC device-tree binding.
> -
> -While the RISC-V ISA doesn't specify a memory layout for the PLIC, the
> -"sifive,plic-1.0.0" device is a concrete implementation of the PLIC that
> -contains a specific memory layout, which is documented in chapter 8 of the
> -SiFive U5 Coreplex Series Manual <https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf>.
> -
> -Required properties:
> -- compatible : "sifive,plic-1.0.0" and a string identifying the actual
> -  detailed implementation in case that specific bugs need to be worked around.
> -- #address-cells : should be <0> or more.
> -- #interrupt-cells : should be <1> or more.
> -- interrupt-controller : Identifies the node as an interrupt controller.
> -- reg : Should contain 1 register range (address and length).
> -- interrupts-extended : Specifies which contexts are connected to the PLIC,
> -  with "-1" specifying that a context is not present.  Each node pointed
> -  to should be a riscv,cpu-intc node, which has a riscv node as parent.
> -- riscv,ndev: Specifies how many external interrupts are supported by
> -  this controller.
> -
> -Example:
> -
> -	plic: interrupt-controller@c000000 {
> -		#address-cells = <0>;
> -		#interrupt-cells = <1>;
> -		compatible = "sifive,plic-1.0.0", "sifive,fu540-c000-plic";
> -		interrupt-controller;
> -		interrupts-extended = <
> -			&cpu0-intc 11
> -			&cpu1-intc 11 &cpu1-intc 9
> -			&cpu2-intc 11 &cpu2-intc 9
> -			&cpu3-intc 11 &cpu3-intc 9
> -			&cpu4-intc 11 &cpu4-intc 9>;
> -		reg = <0xc000000 0x4000000>;
> -		riscv,ndev = <10>;
> -	};
> diff --git a/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml
> new file mode 100644
> index 0000000..95c8c85
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml
> @@ -0,0 +1,107 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +# Copyright (C) 2020 SiFive, Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/interrupt-controller/sifive,plic-1.0.0.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: SiFive Platform-Level Interrupt Controller (PLIC)
> +
> +description:
> +  SiFive SOCs include an implementation of the Platform-Level Interrupt Controller
> +  (PLIC) high-level specification in the RISC-V Privileged Architecture
> +  specification. The PLIC connects all external interrupts in the system to all
> +  hart contexts in the system, via the external interrupt source in each hart.
> +
> +  A hart context is a privilege mode in a hardware execution thread. For example,
> +  in an 4 core system with 2-way SMT, you have 8 harts and probably at least two
> +  privilege modes per hart; machine mode and supervisor mode.
> +
> +  Each interrupt can be enabled on per-context basis. Any context can claim
> +  a pending enabled interrupt and then release it once it has been handled.
> +
> +  Each interrupt has a configurable priority. Higher priority interrupts are
> +  serviced first.  Each context can specify a priority threshold. Interrupts
> +  with priority below this threshold will not cause the PLIC to raise its
> +  interrupt line leading to the context.
> +
> +  While the PLIC supports both edge-triggered and level-triggered interrupts,
> +  interrupt handlers are oblivious to this distinction and therefore it is not
> +  specified in the PLIC device-tree binding.
> +
> +  While the RISC-V ISA doesn't specify a memory layout for the PLIC, the
> +  "sifive,plic-1.0.0" device is a concrete implementation of the PLIC that
> +  contains a specific memory layout, which is documented in chapter 8 of the
> +  SiFive U5 Coreplex Series Manual <https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf>.
> +
> +maintainers:
> +  - Sagar Kadam <sagar.kadam@sifive.com>
> +  - Paul Walmsley  <paul.walmsley@sifive.com>
> +  - Palmer Dabbelt <palmer@dabbelt.com>
> +
> +allOf:
> +  - $ref: /schemas/interrupt-controller.yaml#

Don't need this. It gets selected matching on node name.

> +
> +properties:
> +  compatible:
> +    items:
> +      - const: sifive,plic-1.0.0
> +      - const: sifive,fu540-c000-plic

Somehow these ended up in the wrong order. Should be most specific to 
least specific.

> +
> +    description:
> +      Should be "sifive,plic-1.0.0" and a string identifying the actual
> +      detailed implementation in case that specific bugs need to be worked around.

Drop this.

> +
> +  reg:
> +    maxItems: 1
> +    description:  Should contain 1 register range (address and length).

Drop this. The schema says this...

> +
> +  '#address-cells':
> +    const: 0
> +    description: Should be <0> or more.

Drop. 'or more' is wrong. If there's a case with more, it will need to 
be documented.

> +
> +  '#interrupt-cells':
> +    const: 1
> +    description: Should be <1> or more.

Same here.

> +
> +  interrupt-controller: true
> +
> +  interrupts-extended:
> +    minItems: 1
> +    description:
> +      Specifies which contexts are connected to the PLIC, with "-1" specifying
> +      that a context is not present. Each node pointed to should be a
> +      riscv,cpu-intc node, which has a riscv node as parent.
> +
> +  riscv,ndev:
> +    $ref: "/schemas/types.yaml#/definitions/uint32"
> +    description:
> +      Specifies how many external interrupts are supported by this controller.
> +
> +required:
> +  - compatible
> +  - '#address-cells'
> +  - '#interrupt-cells'
> +  - interrupt-controller
> +  - reg
> +  - interrupts-extended
> +  - riscv,ndev
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    plic: interrupt-controller@c000000 {
> +      #address-cells = <0>;
> +      #interrupt-cells = <1>;
> +      compatible = "sifive,plic-1.0.0", "sifive,fu540-c000-plic";
> +      interrupt-controller;
> +      interrupts-extended = <
> +        &cpu0_intc 11
> +        &cpu1_intc 11 &cpu1_intc 9
> +        &cpu2_intc 11 &cpu2_intc 9
> +        &cpu3_intc 11 &cpu3_intc 9
> +        &cpu4_intc 11 &cpu4_intc 9>;
> +      reg = <0xc000000 0x4000000>;
> +      riscv,ndev = <10>;
> +    };
> -- 
> 2.7.4
> 

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