Re: [PATCH] dt-bindings: arm: arm,vexpress-scc: convert to DT schema

[Liviu Dudau <liviu.dudau@arm.com>]

Hello,

Thanks for your patch, I have some suggestions to improve it.

On Tue, Mar 31, 2026 at 10:59:59PM +0530, Khushal Chitturi wrote:
> Convert the ARM Versatile Express Serial Configuration Controller
> bindings to DT schema.
> 
> Signed-off-by: Khushal Chitturi <khushalchitturi@gmail.com>
> ---
> Note:
> * This patch is part of the GSoC2026 application process for device tree bindings conversions
> * https://github.com/LinuxFoundationGSoC/ProjectIdeas/wiki/GSoC-2026-Device-Tree-Bindings
> 
>  .../bindings/arm/arm,vexpress-scc.yaml        | 51 +++++++++++++++++++
>  .../devicetree/bindings/arm/vexpress-scc.txt  | 33 ------------
>  2 files changed, 51 insertions(+), 33 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/arm/arm,vexpress-scc.yaml
>  delete mode 100644 Documentation/devicetree/bindings/arm/vexpress-scc.txt
> 
> diff --git a/Documentation/devicetree/bindings/arm/arm,vexpress-scc.yaml b/Documentation/devicetree/bindings/arm/arm,vexpress-scc.yaml
> new file mode 100644
> index 000000000000..7870410211a0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/arm,vexpress-scc.yaml
> @@ -0,0 +1,51 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/arm/arm,vexpress-scc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: ARM Versatile Express Serial Configuration Controller
> +
> +maintainers:
> +  - Pawel Moll <pawel.moll@arm.com>

I'm not sure Pawel wants to be maintainer for this file, maybe add me and Sudeep
instead. I'd also wait until Pawel replies.

> +
> +description: |
> +  Test chips for ARM Versatile Express platform implement SCC (Serial
> +  Configuration Controller) interface, used to set initial conditions
> +  for the test chip.
> +
> +  In some cases its registers are also mapped in normal address space
> +  and can be used to obtain runtime information about the chip internals
> +  (like silicon temperature sensors) and as interface to other subsystems
> +  like platform configuration control and power management.
> +
> +properties:
> +  compatible:
> +    items:
> +      - pattern: "^arm,vexpress-scc,[a-z0-9_-]+$"

This is way too generic. I suggest you have a look at bindings/arm/arm,vexpress-juno.yaml
and see how we defined the possible values for the compatible string there. For the initial
conversion I would suggest you only define as valid the "arm,vexpress-scc,v2p-ca15_a7" value
but in a way similar to Juno's file so that it can be extended in the future.

Best regards,
Liviu

> +      - const: arm,vexpress-scc
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    bus {
> +        #address-cells = <2>;
> +        #size-cells = <2>;
> +
> +        scc@7fff0000 {
> +            compatible = "arm,vexpress-scc,v2p-ca15_a7", "arm,vexpress-scc";
> +            reg = <0 0x7fff0000 0 0x1000>;
> +            interrupts = <0 95 4>;
> +        };
> +    };
> +...
> diff --git a/Documentation/devicetree/bindings/arm/vexpress-scc.txt b/Documentation/devicetree/bindings/arm/vexpress-scc.txt
> deleted file mode 100644
> index ae5043e42e5d..000000000000
> --- a/Documentation/devicetree/bindings/arm/vexpress-scc.txt
> +++ /dev/null
> @@ -1,33 +0,0 @@
> -ARM Versatile Express Serial Configuration Controller
> ------------------------------------------------------
> -
> -Test chips for ARM Versatile Express platform implement SCC (Serial
> -Configuration Controller) interface, used to set initial conditions
> -for the test chip.
> -
> -In some cases its registers are also mapped in normal address space
> -and can be used to obtain runtime information about the chip internals
> -(like silicon temperature sensors) and as interface to other subsystems
> -like platform configuration control and power management.
> -
> -Required properties:
> -
> -- compatible value: "arm,vexpress-scc,<model>", "arm,vexpress-scc";
> -		    where <model> is the full tile model name (as used
> -		    in the tile's Technical Reference Manual),
> -		    eg. for Coretile Express A15x2 A7x3 (V2P-CA15_A7):
> -	compatible = "arm,vexpress-scc,v2p-ca15_a7", "arm,vexpress-scc";
> -
> -Optional properties:
> -
> -- reg: when the SCC is memory mapped, physical address and size of the
> -       registers window
> -- interrupts: when the SCC can generate a system-level interrupt
> -
> -Example:
> -
> -	scc@7fff0000 {
> -		compatible = "arm,vexpress-scc,v2p-ca15_a7", "arm,vexpress-scc";
> -		reg = <0 0x7fff0000 0 0x1000>;
> -		interrupts = <0 95 4>;
> -	};
> -- 
> 2.53.0
> 

-- 
====================
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| but they're not |
| giving me the   |
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