Re: [PATCH v4 1/2] dt-bindings: interconnect: qcom: add msm8660 NoC

[Krzysztof Kozlowski]

On Sat, Jun 06, 2026 at 03:00:46PM +0200, Herman van Hazendonk wrote:
> Add a dt-binding schema and an interconnect master/slave ID header for
> the MSM8x60 family (MSM8260/MSM8660/APQ8060) Network-on-Chip.  The
> chip exposes four NoC fabrics that the qnoc-msm8660 driver models:
> 
>   AFAB  - Applications fabric (Scorpion CPU + L2)
>   SFAB  - System fabric (DMA, SPS, security)
>   MMFAB - Multimedia fabric (MDP, GPU, camera, video, rotator)
>   DFAB  - Daytona fabric (SDC, ADM master/slave)
> 
> The schema covers all four compatible strings, per-fabric clock-name
> lists (bus / bus_a / ebi1 / ebi1_a for AFAB; bus / bus_a / smi /
> smi_a for MMFAB; bus / bus_a for SFAB and DFAB), the required
> qcom,rpm phandle through which the provider hands the arbitration
> buffer to RPM firmware, and #interconnect-cells = <1>.
> 
> The ID header lists per-fabric master / slave / gateway indices
> derived from the legacy vendor msm_bus_board_8660.c enums,
> normalised to the upstream interconnect-framework naming convention.
> 
> Assisted-by: Claude:claude-opus-4-7 Sashiko:claude-haiku-4-5
> Signed-off-by: Herman van Hazendonk <github.com@xxxxxxxxxx>
> ---
>  .../bindings/interconnect/qcom,msm8660.yaml        | 164 +++++++++++++++++++++
>  include/dt-bindings/interconnect/qcom,msm8660.h    | 156 ++++++++++++++++++++
>  2 files changed, 320 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/interconnect/qcom,msm8660.yaml b/Documentation/devicetree/bindings/interconnect/qcom,msm8660.yaml
> new file mode 100644
> index 000000000000..776717d4212f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/interconnect/qcom,msm8660.yaml
> @@ -0,0 +1,164 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/interconnect/qcom,msm8660.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Qualcomm MSM8x60 family Network-On-Chip interconnect
> +
> +maintainers:
> +  - Herman van Hazendonk <github.com@xxxxxxxxxx>
> +
> +description: |
> +  The Qualcomm MSM8x60 family (MSM8260/MSM8660/APQ8060) NoC is split into
> +  four fabrics, each modelled as a separate interconnect provider:
> +
> +    APPSS fabric    Scorpion CPU cluster, L2 cache, EBI (DDR) memory.
> +    System fabric   DMA controllers, modem and LPASS cross-domain links,
> +                    security peripherals.
> +    Multimedia fab  Display (MDP), GPU, camera (VFE), video codec (VPE),
> +                    JPEG, with the SMI scratchpad as the local slave.
> +    Daytona fabric  SDC1..SDC5 controllers and ADM master/slave channels.
> +
> +  Each provider programs fabric arbitration (per-master priority tier and
> +  per-slave bandwidth vote) through RPM firmware via the qcom,rpm parent
> +  controller, in addition to scaling its bus clocks via clk_set_rate.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - qcom,msm8660-apps-fabric
> +      - qcom,msm8660-system-fabric
> +      - qcom,msm8660-mmss-fabric
> +      - qcom,msm8660-daytona-fabric
> +
> +  '#interconnect-cells':
> +    const: 1
> +    description:
> +      Each consumer phandle takes the form <provider node-id> where node-id
> +      indexes the per-fabric ID array in
> +      <dt-bindings/interconnect/qcom,msm8660.h>.  Pinned to 1 because the
> +      driver uses of_icc_xlate_onecell, which strictly requires a single cell.
> +
> +  clocks:
> +    minItems: 2
> +    maxItems: 4
> +
> +  clock-names:
> +    minItems: 2
> +    maxItems: 4
> +
> +  qcom,rpm:
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +    description:
> +      Phandle to the qcom,rpm node.  The interconnect provider hands the
> +      per-fabric arbitration buffer to RPM firmware through this resource,
> +      so a production device tree must point at the system RPM.

"production device tree" is confusing - no clue how does it matter for
the bindings. Like a non-production would be different?

Anyway, explain the hardware - the interconnects are part of RPM, no? So
why do you need another resource?

I do not see any resources for talking with the hardware, so it seems
you just added this as a fake phandle to avoid properly repersenting the
hardware.

> +
> +required:
> +  - compatible
> +  - clocks
> +  - clock-names
> +  - qcom,rpm
> +  - '#interconnect-cells'
> +
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          const: qcom,msm8660-apps-fabric
> +    then:
> +      properties:
> +        clocks:
> +          items:
> +            - description: APPSS fabric bus clock (active vote)
> +            - description: APPSS fabric bus clock (active+sleep vote)
> +            - description: EBI1 (DDR) channel clock (active vote)

Is there EBI0?

> +            - description: EBI1 (DDR) channel clock (active+sleep vote)
> +        clock-names:
> +          items:
> +            - const: bus
> +            - const: bus_a
> +            - const: ebi1

If on, then this is just ebi or mc

> +            - const: ebi1_a
> +  - if:
> +      properties:
> +        compatible:
> +          enum:
> +            - qcom,msm8660-system-fabric
> +            - qcom,msm8660-daytona-fabric
> +    then:
> +      properties:
> +        clocks:
> +          items:
> +            - description: Fabric bus clock (active vote)
> +            - description: Fabric bus clock (active+sleep vote)
> +        clock-names:
> +          items:
> +            - const: bus
> +            - const: bus_a
> +  - if:
> +      properties:
> +        compatible:
> +          const: qcom,msm8660-mmss-fabric
> +    then:
> +      properties:
> +        clocks:
> +          items:
> +            - description: MMSS fabric bus clock (active vote)
> +            - description: MMSS fabric bus clock (active+sleep vote)
> +            - description: SMI scratchpad clock (active vote)
> +            - description: SMI scratchpad clock (active+sleep vote)
> +        clock-names:
> +          items:
> +            - const: bus
> +            - const: bus_a
> +            - const: smi
> +            - const: smi_a
> +
> +unevaluatedProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/qcom,rpmcc.h>
> +
> +    interconnect-afab {
> +        compatible = "qcom,msm8660-apps-fabric";
> +        clocks = <&rpmcc RPM_APPS_FABRIC_CLK>,
> +                 <&rpmcc RPM_APPS_FABRIC_A_CLK>,
> +                 <&rpmcc RPM_EBI1_CLK>,
> +                 <&rpmcc RPM_EBI1_A_CLK>;
> +        clock-names = "bus", "bus_a", "ebi1", "ebi1_a";
> +        qcom,rpm = <&rpm>;
> +        #interconnect-cells = <1>;
> +    };

One example is enough, all of these are basically the same.

Best regards,
Krzysztof