Re: [PATCH 1/2] dt-bindings: timer: Add ARM SSE(Subsystems for Embedded) timer

Re: [PATCH 1/2] dt-bindings: timer: Add ARM SSE(Subsystems for Embedded) timer

[Jisheng Zhang]

On Thu, Aug 21, 2025 at 11:24:28PM +0800, Jisheng Zhang wrote:
> Add binding doc for the ARM SSE(Subsystems for Embedded) timer. Here
> is the document URL:
> https://developer.arm.com/documentation/107610/0000/System-timer-components?lang=en
> 
> Although the IP is mostly seen on MCU SoC platforms, but nothing
> prevent it from being integrated into linux capable SoC platforms.
> 
> The IP core may have a system counter to generate timestamp value,
> a system timer to raise an interrupt when a period has elapsed, and
> a System Watchdog to detect errant system behaviour then reset the
> system if a period elapses without ping.
> 
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  .../bindings/timer/arm,sse_timer.yaml         | 90 +++++++++++++++++++
>  1 file changed, 90 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/timer/arm,sse_timer.yaml
> 
> diff --git a/Documentation/devicetree/bindings/timer/arm,sse_timer.yaml b/Documentation/devicetree/bindings/timer/arm,sse_timer.yaml
> new file mode 100644
> index 000000000000..37a79f9052d0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/timer/arm,sse_timer.yaml
> @@ -0,0 +1,90 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/timer/arm,sse_timer.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: ARM SSE(Subsystems for Embedded) system timer
> +
> +maintainers:
> +  - Jisheng Zhang <jszhang@kernel.org>
> +
> +description: |+
> +  ARM SSE(Subsystems for Embedded) system timer core may have a system counter
> +  to generate timestamp value, a system timer to raise an interrupt when a
> +  period has elapsed, and a System Watchdog to detect errant system behaviour
> +  then reset the system if a period elapses without ping.
> +
> +properties:
> +  compatible:
> +    items:
> +      - enum:
> +          - arm,sse-timer
> +
> +  reg:
> +    maxItems: 1
> +    description: The system counter control frame base
> +
> +  clocks:
> +    maxItems: 1
> +
> +  '#address-cells':
> +    enum: [1, 2]
> +
> +  '#size-cells':
> +    const: 1
> +
> +  ranges: true
> +
> +patternProperties:
> +  '^frame@[0-9a-f]+$':
> +    type: object
> +    additionalProperties: false
> +    description: A timer node has some frame sub-nodes, each frame can be timer frame or watchdog frame. Each frame has the following properties.
> +    properties:
> +      interrupts:
> +        minItems: 1
> +        items:
> +          - description: timer irq
> +
> +      reg:
> +        minItems: 1
> +        items:
> +          - description: 1st view base address
> +          - description: 2nd optional view base address if this is a watchdog frame
> +
> +    required:
> +      - interrupts
> +      - reg
> +
> +required:
> +  - compatible
> +  - reg
> +  - '#address-cells'
> +  - '#size-cells'
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    timer@f7f3e000 {
> +      compatible = "arm,sse-timer";
> +      #address-cells = <1>;
> +      #size-cells = <1>;
> +      ranges;
> +      reg = <0xf7f3e000 0x2000>;
> +      clocks = <&core_clk>;
> +
> +      frame@f7f20000 {
> +        reg = <0xf7f20000 0x1000>;
> +        interrupts = <0 26 0x8>;
> +      };
> +
> +      frame@f7f30000 {
> +        interrupts = <0 15 0x8>;
> +        reg = <0xf7f32000 0x1000>,
> +              <0xf7f33000 0x1000>;
> +      };
> +    };
> +
> +...
> -- 
> 2.50.1
> 

Re: [PATCH 1/2] dt-bindings: timer: Add ARM SSE(Subsystems for Embedded) timer

[Jisheng Zhang]

On Thu, Aug 21, 2025 at 05:39:48PM -0500, Rob Herring (Arm) wrote:
> 
> On Thu, 21 Aug 2025 23:24:28 +0800, Jisheng Zhang wrote:
> > Add binding doc for the ARM SSE(Subsystems for Embedded) timer. Here
> > is the document URL:
> > https://developer.arm.com/documentation/107610/0000/System-timer-components?lang=en
> > 
> > Although the IP is mostly seen on MCU SoC platforms, but nothing
> > prevent it from being integrated into linux capable SoC platforms.
> > 
> > The IP core may have a system counter to generate timestamp value,
> > a system timer to raise an interrupt when a period has elapsed, and
> > a System Watchdog to detect errant system behaviour then reset the
> > system if a period elapses without ping.
> > 
> > Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> > ---
> >  .../bindings/timer/arm,sse_timer.yaml         | 90 +++++++++++++++++++
> >  1 file changed, 90 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/timer/arm,sse_timer.yaml
> > 
> 
> My bot found errors running 'make dt_binding_check' on your patch:

Oops, thanks for the hint. I would like to collect feedbacks to the
implementation itself, then fix the dt errors/warnings in v2.

Thanks
> 
> yamllint warnings/errors:
> ./Documentation/devicetree/bindings/timer/arm,sse_timer.yaml:43:111: [warning] line too long (145 > 110 characters) (line-length)
> 
> dtschema/dtc warnings/errors:
> /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/timer/arm,sse_timer.yaml: patternProperties:^frame@[0-9a-f]+$:properties:interrupts: 'oneOf' conditional failed, one must be fixed:
> 	[{'description': 'timer irq'}] is too short
> 	False schema does not allow 1
> 	hint: "minItems" is only needed if less than the "items" list length
> 	from schema $id: http://devicetree.org/meta-schemas/items.yaml#
> 
> doc reference errors (make refcheckdocs):
> 
> See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20250821152429.26995-2-jszhang@kernel.org
> 
> The base for the series is generally the latest rc1. A different dependency
> should be noted in *this* patch.
> 
> If you already ran 'make dt_binding_check' and didn't see the above
> error(s), then make sure 'yamllint' is installed and dt-schema is up to
> date:
> 
> pip3 install dtschema --upgrade
> 
> Please check and re-submit after running the above command yourself. Note
> that DT_SCHEMA_FILES can be set to your schema file to speed up checking
> your schema. However, it must be unset to test all examples with your schema.
>