Re: [PATCH v3 03/12] dt-bindings: bus: document the stm32 debug bus

[Rob Herring <robh@kernel.org>]

On Wed, Jan 21, 2026 at 01:34:37PM +0100, Gatien Chevallier wrote:
> Document the stm32 debug bus. The debug bus is responsible for
> checking the debug sub-system accessibility before probing any related
> drivers.
> 
> Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
> ---
>  .../bindings/bus/st,stm32mp131-dbg-bus.yaml        | 79 ++++++++++++++++++++++
>  1 file changed, 79 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/bus/st,stm32mp131-dbg-bus.yaml b/Documentation/devicetree/bindings/bus/st,stm32mp131-dbg-bus.yaml
> new file mode 100644
> index 000000000000..2db35e41e76c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/bus/st,stm32mp131-dbg-bus.yaml
> @@ -0,0 +1,79 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/bus/st,stm32mp131-dbg-bus.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: STM32 Coresight bus
> +
> +maintainers:
> +  - Gatien Chevallier <gatien.chevallier@foss.st.com>
> +
> +description:
> +  The STM32 debug bus is in charge of checking the debug configuration
> +  of the platform before probing the peripheral drivers that rely on the debug
> +  domain.
> +
> +properties:
> +  compatible:
> +    items:
> +      - enum:
> +          - st,stm32mp131-dbg-bus
> +          - st,stm32mp151-dbg-bus
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 1
> +
> +  ranges: true
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#access-controller-cells":
> +    const: 1
> +    description:
> +      Contains the debug profile necessary to access the peripheral.
> +
> +patternProperties:
> +  "^.*@[0-9a-f]+$":
> +    description: Debug related peripherals
> +    type: object
> +
> +    additionalProperties: true
> +
> +    required:
> +      - access-controllers
> +
> +required:
> +  - "#access-controller-cells"
> +  - "#address-cells"
> +  - "#size-cells"
> +  - compatible
> +  - ranges
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/stm32mp1-clks.h>
> +
> +    dbg_bus: bus@50080000 {
> +      compatible = "st,stm32mp131-dbg-bus";
> +      reg = <0x50080000 0x3f80000>;

That's a lot of registers... Yet the bus driver doesn't access any. 
Looks to me like this belongs in ranges instead if there aren't any bus 
registers. Or its size should be just the registers and then the whole 
region size goes in ranges.

> +      #address-cells = <1>;
> +      #size-cells = <1>;
> +      #access-controller-cells = <1>;
> +      ranges;
> +
> +      cs_cti_trace: cti@50094000 {
> +        compatible = "arm,coresight-cti", "arm,primecell";
> +        reg = <0x50094000 0x1000>;
> +        clocks = <&rcc CK_DBG>;
> +        clock-names = "apb_pclk";
> +        access-controllers = <&dbg_bus 0>;
> +      };
> +    };
> 
> -- 
> 2.43.0
>