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SubjectRe: [PATCH 3/6] dt-bindings: riscv: convert cpu binding to json-schema
On Thu, Apr 11, 2019 at 3:43 AM Paul Walmsley <paul.walmsley@sifive.com> wrote:
>
> At Rob's request, we're starting to migrate our DT binding
> documentation to json-schema YAML format. Start by converting our cpu
> binding documentation. While doing so, document more properties and
> nodes. This includes adding binding documentation support for the E51
> and U54 CPU cores ("harts") that are present on this SoC. These cores
> are described in:
>
> https://static.dev.sifive.com/FU540-C000-v1.0.pdf
>
> This cpus.yaml file is intended to be a starting point and to
> evolve over time. It passes dt-doc-validate as of the yaml-bindings
> commit 4c79d42e9216.
>
> This patch was originally based on the ARM json-schema binding
> documentation as added by commit 672951cbd1b7 ("dt-bindings: arm: Convert
> cpu binding to json-schema").
>
> Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
> Signed-off-by: Paul Walmsley <paul@pwsan.com>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: devicetree@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: linux-riscv@lists.infradead.org
> ---
> .../devicetree/bindings/riscv/cpus.yaml | 274 ++++++++++++++++++
> 1 file changed, 274 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/riscv/cpus.yaml
>
> diff --git a/Documentation/devicetree/bindings/riscv/cpus.yaml b/Documentation/devicetree/bindings/riscv/cpus.yaml
> new file mode 100644
> index 000000000000..11ade807fd49
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/riscv/cpus.yaml
> @@ -0,0 +1,274 @@
> +# SPDX-License-Identifier: GPL-2.0
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/riscv/cpus.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: RISC-V bindings for 'cpus' DT nodes
> +
> +maintainers:
> + - Paul Walmsley <paul.walmsley@sifive.com>
> + - Palmer Dabbelt <palmer@sifive.com>
> +
> +description: |+
> + In SoC device tree data files, the layout of CPUs is described in
> + the "cpus" node. This node in turn contains a number of subnodes
> + representing CPUs, which define properties for every cpu.
> +
> + Bindings for CPU nodes follow the Devicetree Specification, available from:
> +
> + https://www.devicetree.org/specifications/
> +
> + with updates for RISC-V cores provided in this document.
> +
> + ================================
> + Convention used in this document
> + ================================
> +
> + This document follows the conventions described in the Devicetree
> + Specification, with the addition:
> +
> + - square brackets define bitfields, e.g. reg[7:0] represents the
> + value of the bitfield in the reg property contained in bits 7 down
> + to 0
> +
> + =====================================
> + cpus and cpu node bindings definition
> + =====================================
> +
> + If a Devicetree file is used to provide hardware data to the kernel,
> + the RISC-V architecture requires the cpus and cpu nodes to be
> + present and contain the properties described below.
> +
> +properties:
> + $nodename:
> + const: cpus
> + description: Container of cpu nodes
> +
> + '#address-cells':
> + const: 1
> + description: |
> + A single unsigned 32-bit integer uniquely identifies
> + each RISC-V hart in a system. (See the "reg" node under
> + the "cpu" node, below).
> +
> + '#size-cells':
> + const: 0
> +
> +patternProperties:
> + '^cpu@[0-9a-f]+$':
> + properties:
> + device_type:
> + const: cpu
> +
> + reg:
> + maxItems: 1
> + description: |
> + Set the "reg" property to the hart ID of this CPU node.
> + Each value in this property must be unique in the scope
> + of the Devicetree file that contains it.
> +
> + compatible:
> + items:
> + - const: riscv

Wrong order here. This should be last.

> + - enum:
> + - sifive,rocket0
> + - sifive,e5
> + - sifive,e51
> + - sifive,u54-mc
> + - sifive,u54
> + - sifive,u5
> + description: |
> + Identifies that the hart uses the RISC-V instruction set
> + and identifies the type of the hart.
> +
> + mmu-type:
> + items:
> + - enum:

If a single value, then you can drop 'items'.

> + - riscv,sv32
> + - riscv,sv39
> + - riscv,sv48
> + description: |
> + Identifies the MMU address translation mode used on this
> + hart. These values originate from the RISC-V Privileged
> + Specification document, available from
> + https://riscv.org/specifications/
> +
> + riscv,isa:

This needs to have a $ref to a type schema. (Under an 'allOf' list
with this enum)

> + items:
> + - enum:

Also don't need items here if a single value.

> + - rv64imac
> + - rv64imafdc
> + description: |
> + Identifies the specific RISC-V instruction set architecture
> + supported by the hart. These are documented in the RISC-V
> + User-Level ISA document, available from
> + https://riscv.org/specifications/
> +
> + The RISC-V Linux port only will execute on a subset of these

What Linux does isn't relevant to the binding.

> + values. However, other hart cores may be present in the
> + Devicetree hardware description file that do not run Linux.
> +
> + timebase-frequency:
> + maxItems: 1

Not an array.

> + description: |
> + Specifies the clock frequency of the system timer in Hz.
> + This value is common to all harts in this Linux system image.
> +
> + i-cache-block-size:
> + maxItems: 1

Not an array. Surely you can define either the set of possible values
or min/max values. Same comment on the rest of the cache props.

Are the cache attributes really not discoverable?

> + description: |
> + Specifies the size, in bytes, of an instruction cache line.
> +
> + i-cache-sets:
> + maxItems: 1
> + description: |
> + Specifies the number of sets in the hart's instruction cache.
> +
> + i-cache-size:
> + maxItems: 1
> + description: |
> + Specifies the size, in bytes, of the hart's instruction cache.
> +
> + i-tlb-sets:
> + maxItems: 1
> + description: |
> + Specifies the number of sets in the hart's instruction TLB.
> + If present, the "tlb-split" property must be set.

'dependencies' can express this for you. We do need a core schema for
all these to define the type and maybe dependencies can be there.

> +
> + i-tlb-size:
> + maxItems: 1
> + description: |
> + Specifies the number of entries in the hart's instruction TLB.
> + If present, the "tlb-split" property must be set.
> +
> + d-cache-block-size:
> + maxItems: 1
> + description: |
> + Specifies the size, in bytes, of a data cache line.
> +
> + d-cache-sets:
> + maxItems: 1
> + description: |
> + Specifies the number of sets in the hart's data cache.
> +
> + d-cache-size:
> + maxItems: 1
> + description: |
> + Specifies the size, in bytes, of the hart's data cache.
> +
> + d-tlb-sets:
> + maxItems: 1
> + description: |
> + Specifies the number of sets in the hart's data TLB.
> + If present, the "tlb-split" property must be set.
> +
> + d-tlb-size:
> + maxItems: 1
> + description: |
> + Specifies the number of entries in the hart's data TLB.
> + If present, the "tlb-split" property must be set.
> +
> + tlb-split: true
> +
> + patternProperties:
> + '^interrupt-controller@[0-9a-f]+$':

No 'reg', so should not have a unit-address.

> + properties:
> + $nodename:

You don't need this as we just defined it above.

> + const: interrupt-controller
> + description: Describes the CPU's local interrupt controller
> +
> + '#interrupt-cells':
> + const: 1
> +
> + compatible:
> + const: riscv,cpu-intc
> +
> + interrupt-controller: true
> +
> + required:
> + - '#interrupt-cells'
> + - compatible
> + - interrupt-controller
> +
> + required:
> + - device_type
> + - reg
> + - compatible
> + - riscv,isa
> + - timebase-frequency
> +
> +required:
> + - '#address-cells'
> + - '#size-cells'
> +
> +examples:
> + - |
> + // Example 1: SiFive Freedom U540G Development Kit
> + cpus {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + timebase-frequency = <1000000>;
> + cpu@0 {
> + clock-frequency = <0>;
> + compatible = "sifive,rocket0", "riscv";
> + device_type = "cpu";
> + i-cache-block-size = <64>;
> + i-cache-sets = <128>;
> + i-cache-size = <16384>;
> + reg = <0>;
> + riscv,isa = "rv64imac";

> + sifive,dtim = <&L8>;
> + sifive,itim = <&L7>;

Not documented.

> + status = "okay";

Don't show status in examples.

> + L10: interrupt-controller {
> + #interrupt-cells = <1>;
> + compatible = "riscv,cpu-intc";
> + interrupt-controller;
> + };
> + };
> + cpu@1 {
> + clock-frequency = <0>;
> + compatible = "sifive,rocket0", "riscv";
> + d-cache-block-size = <64>;
> + d-cache-sets = <64>;
> + d-cache-size = <32768>;
> + d-tlb-sets = <1>;
> + d-tlb-size = <32>;
> + device_type = "cpu";
> + i-cache-block-size = <64>;
> + i-cache-sets = <64>;
> + i-cache-size = <32768>;
> + i-tlb-sets = <1>;
> + i-tlb-size = <32>;
> + mmu-type = "riscv,sv39";
> + reg = <1>;
> + riscv,isa = "rv64imafdc";
> + status = "okay";
> + tlb-split;
> + L13: interrupt-controller {
> + #interrupt-cells = <1>;
> + compatible = "riscv,cpu-intc";
> + interrupt-controller;
> + };
> + };
> + };
> +
> + - |
> + // Example 2: Spike ISA Simulator with 1 Hart
> + cpus {
> + cpu@0 {
> + device_type = "cpu";
> + reg = <0>;
> + status = "okay";
> + compatible = "riscv";
> + riscv,isa = "rv64imafdc";
> + mmu-type = "riscv,sv48";
> + interrupt-controller {
> + #interrupt-cells = <1>;
> + interrupt-controller;
> + compatible = "riscv,cpu-intc";
> + };
> + };
> + };
> +...
> --
> 2.20.1
>

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