Re: [PATCH 1/6] dt-bindings: ptp: Document the TSCSS on Qualcomm Lemans and Monaco SoCs

[Krzysztof Kozlowski <krzk@kernel.org>]

On 27/07/2026 16:10, Imran Shaik wrote:
> Add Devicetree bindings for the Timestamp Counter Subsystem (TSCSS) found
> on Qualcomm Lemans and Monaco SoCs.
> 
> TSCSS is a time synchronization subsystem composed of two main blocks:
> Timestamp Counter (TSC) and Event Timestamp Unit (ETU). The TSC block
> provides a continuously running counter used for timekeeping, while the
> ETU captures timestamps for external hardware event triggers.
> 
> Co-developed-by: Taniya Das <taniya.das@oss.qualcomm.com>
> Signed-off-by: Taniya Das <taniya.das@oss.qualcomm.com>
> Signed-off-by: Imran Shaik <imran.shaik@oss.qualcomm.com>
> ---
>  .../devicetree/bindings/ptp/qcom,lemans-tscss.yaml | 198 +++++++++++++++++++++
>  1 file changed, 198 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/ptp/qcom,lemans-tscss.yaml b/Documentation/devicetree/bindings/ptp/qcom,lemans-tscss.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..4cbe4b00ff7dcacbd8cc111e2b4b61ebce7104aa
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/ptp/qcom,lemans-tscss.yaml
> @@ -0,0 +1,198 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/ptp/qcom,lemans-tscss.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Timestamp Counter Subsystem (TSCSS) on Qualcomm Lemans and Monaco SoCs
> +
> +maintainers:
> +  - Imran Shaik <imran.shaik@oss.qualcomm.com>
> +  - Taniya Das <taniya.das@oss.qualcomm.com>
> +
> +description: |
> +  Qualcomm TSCSS is a time synchronization subsystem composed of two main
> +  blocks - the Time Stamp Counter (TSC) and the Event Timestamp Unit (ETU).
> +
> +  The TSC block is a timestamp generator that maintains a running counter used
> +  for system timekeeping, and is functional with just the AHB and counter
> +  clocks.
> +  The ETU block is optional and captures TSC timestamps for external
> +  hardware events, each ETU slice binding a slice identifier to an external
> +  event selector. Support for the ETU block requires the additional ETU
> +  clock along with the summary interrupt and slice subnodes.
> +
> +properties:
> +  compatible:
> +    oneOf:
> +      - const: qcom,lemans-tscss

There is no such SoC upstream.


> +      - items:
> +          - const: qcom,monaco-tscss

Neither this one.


> +          - const: qcom,lemans-tscss
> +
> +  reg:
> +    maxItems: 1
> +
> +  reg-names:
> +    items:
> +      - const: tsc

Drop names, not really useful.

> +

> +  clocks:
> +    minItems: 2
> +    items:
> +      - description: TSC AHB configuration clock.
> +      - description: TSC global counter clock.
> +      - description: TSC ETU clock.
> +
> +  clock-names:
> +    minItems: 2

Why is this flexible?

> +    items:
> +      - const: ahb
> +      - const: cntr
> +      - const: etu
> +
> +  interrupts:
> +    description: Summary interrupt raised based on external event for any of the ETU slices.

Please follow Linux coding style.

> +    maxItems: 1
> +
> +  interrupt-names:
> +    items:
> +      - const: etu_summary
> +
> +  assigned-clocks: true
> +  assigned-clock-rates: true

Drop. From where did you take it?

> +
> +  "#address-cells":
> +    const: 2
> +
> +  "#size-cells":
> +    const: 2
> +
> +  ranges: true
> +
> +patternProperties:
> +  "^etu-slice@[0-9a-f]+$":
> +    type: object
> +    description: ETU slice configuration
> +    properties:
> +      reg:
> +        maxItems: 1
> +
> +      pinctrl-0: true
> +
> +      pinctrl-names:
> +        items:
> +          - const: default

Heh? Which code do you copy?

> +
> +      qcom,etu-event-sel:
> +        description: Event selection value for this slice.
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +
> +      qcom,etu-slice:
> +        description: ETU slice identifier.

You do not get identifiers. Please read writing bindings.

> +        $ref: /schemas/types.yaml#/definitions/uint32
> +
> +    required:
> +      - reg
> +      - qcom,etu-event-sel
> +      - qcom,etu-slice
> +      - pinctrl-0
> +      - pinctrl-names
> +    unevaluatedProperties: false

Please read writing bindings.

> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - clocks
> +  - clock-names
> +
> +allOf:
> +  - if:
> +      properties:
> +        clock-names:
> +          contains:
> +            const: etu

etu is third clock, what is the point of it?

> +    then:
> +      properties:
> +        clocks:
> +          minItems: 3
> +        clock-names:
> +          minItems: 3
> +      required:
> +        - interrupts
> +        - interrupt-names
> +        - "#address-cells"
> +        - "#size-cells"
> +        - ranges
> +
> +unevaluatedProperties: false

Please read writing bindings.
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/qcom,sa8775p-gcc.h>
> +
> +    soc {
> +      #address-cells = <2>;
> +      #size-cells = <2>;
> +
> +      tscss@1c80000 {
> +        compatible = "qcom,lemans-tscss";
> +        reg = <0x0 0x01c80000 0x0 0x2000>;
> +        reg-names = "tsc";
> +
> +        clocks = <&gcc GCC_TSCSS_AHB_CLK>,
> +                 <&gcc GCC_TSCSS_GLOBAL_CNTR_CLK>;
> +        clock-names = "ahb", "cntr";
> +
> +        assigned-clocks = <&gcc GCC_TSCSS_GLOBAL_CNTR_CLK>;
> +        assigned-clock-rates = <15625000>;
> +      };
> +    };
> +
> +  - |
> +    #include <dt-bindings/clock/qcom,sa8775p-gcc.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +    soc {
> +      #address-cells = <2>;
> +      #size-cells = <2>;
> +
> +      tscss@1c80000 {

This is the same node as previous.

I don't understand this DTS.


Node names should be generic. See also an explanation and list of
examples (not exhaustive) in DT specification:
https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation
If you cannot find a name matching your device, please check in kernel
sources for similar cases or you can grow the spec (via pull request to
DT spec repo).


Best regards,
Krzysztof