Re: [PATCH 5/6] dt-bindings: clock: Document Exynos850 CMU bindings

[Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>]

On 14/09/2021 17:56, Sam Protsenko wrote:
> Provide dt-schema documentation for Exynos850 SoC clock controller.
> 
> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
> ---
>  .../clock/samsung,exynos850-clock.yaml        | 190 ++++++++++++++++++
>  1 file changed, 190 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/samsung,exynos850-clock.yaml
> 
> diff --git a/Documentation/devicetree/bindings/clock/samsung,exynos850-clock.yaml b/Documentation/devicetree/bindings/clock/samsung,exynos850-clock.yaml
> new file mode 100644
> index 000000000000..b69ba4125421
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/samsung,exynos850-clock.yaml
> @@ -0,0 +1,190 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/clock/samsung,exynos850-clock.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Samsung Exynos850 SoC clock controller
> +
> +maintainers:
> +  - Sam Protsenko <semen.protsenko@linaro.org>
> +  - Chanwoo Choi <cw00.choi@samsung.com>
> +  - Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
> +  - Sylwester Nawrocki <s.nawrocki@samsung.com>
> +  - Tomasz Figa <tomasz.figa@gmail.com>
> +
> +description: |
> +  Exynos850 clock controller is comprised of several CMU units, generating
> +  clocks for different domains. Those CMU units are modeled as separate device
> +  tree nodes, and might depend on each other. Root clocks in that clock tree are
> +  two external clocks:: OSCCLK (26 MHz) and RTCCLK (32768 Hz). Those external
> +  clocks must be defined as fixed-rate clocks in dts.
> +
> +  CMU_TOP is a top-level CMU, where all base clocks are prepared using PLLs and
> +  dividers; all other leaf clocks (other CMUs) are usually derived from CMU_TOP.
> +
> +  Each clock is assigned an identifier and client nodes can use this identifier
> +  to specify the clock which they consume. All clocks that available for usage
> +  in clock consumer nodes are defined as preprocessor macros in
> +  'dt-bindings/clock/exynos850.h' header.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - samsung,exynos850-cmu-top
> +      - samsung,exynos850-cmu-core
> +      - samsung,exynos850-cmu-hsi
> +      - samsung,exynos850-cmu-peri
> +
> +  clocks:
> +    minItems: 1
> +    maxItems: 5
> +
> +  clock-names:
> +    minItems: 1
> +    maxItems: 5
> +
> +  "#clock-cells":
> +    const: 1
> +
> +  reg:
> +    maxItems: 1
> +
> +allOf:
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: samsung,exynos850-cmu-top
> +
> +    then:
> +      properties:
> +        clocks:
> +          items:
> +            - description: External reference clock (26 MHz)
> +
> +        clock-names:
> +          items:
> +            - const: oscclk
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: samsung,exynos850-cmu-core
> +
> +    then:
> +      properties:
> +        clocks:
> +          items:
> +            - description: External reference clock (26 MHz)
> +            - description: CMU_CORE bus clock (from CMU_TOP)
> +            - description: CCI clock (from CMU_TOP)
> +            - description: eMMC clock (from CMU_TOP)
> +            - description: SSS clock (from CMU_TOP)
> +
> +        clock-names:
> +          items:
> +            - const: oscclk
> +            - const: dout_core_bus
> +            - const: dout_core_cci
> +            - const: dout_core_mmc_embd
> +            - const: dout_core_sss
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: samsung,exynos850-cmu-hsi
> +
> +    then:
> +      properties:
> +        clocks:
> +          items:
> +            - description: External reference clock (26 MHz)
> +            - description: External RTC clock (32768 Hz)
> +            - description: CMU_HSI bus clock (from CMU_TOP)
> +            - description: SD card clock (from CMU_TOP)
> +            - description: "USB 2.0 DRD clock (from CMU_TOP)"
> +
> +        clock-names:
> +          items:
> +            - const: oscclk
> +            - const: rtcclk
> +            - const: dout_hsi_bus
> +            - const: dout_hsi_mmc_card
> +            - const: dout_hsi_usb20drd
> +
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            const: samsung,exynos850-cmu-peri
> +
> +    then:
> +      properties:
> +        clocks:
> +          items:
> +            - description: External reference clock (26 MHz)
> +            - description: CMU_PERI bus clock (from CMU_TOP)
> +            - description: UART clock (from CMU_TOP)
> +            - description: Parent clock for HSI2C and SPI (from CMU_TOP)
> +
> +        clock-names:
> +          items:
> +            - const: oscclk
> +            - const: dout_peri_bus
> +            - const: dout_peri_uart
> +            - const: dout_peri_ip
> +
> +required:
> +  - compatible
> +  - "#clock-cells"
> +  - clocks
> +  - clock-names
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  # Clock controller node for CMU_PERI
> +  - |
> +    #include <dt-bindings/clock/exynos850.h>
> +
> +    cmu_peri: clock-controller@10030000 {
> +        compatible = "samsung,exynos850-cmu-peri";
> +        reg = <0x10030000 0x8000>;
> +        #clock-cells = <1>;
> +
> +        clocks = <&oscclk>, <&cmu_top DOUT_PERI_BUS>,
> +                 <&cmu_top DOUT_PERI_UART>,
> +                 <&cmu_top DOUT_PERI_IP>;
> +        clock-names = "oscclk", "dout_peri_bus",
> +                      "dout_peri_uart", "dout_peri_ip";
> +    };
> +
> +  # External reference clock (should be provided in particular board DTS)
> +  - |
> +    oscclk: clock-oscclk {
> +        compatible = "fixed-clock";
> +        #clock-cells = <0>;
> +        clock-output-names = "oscclk";
> +        clock-frequency = <26000000>;
> +    };

Skip ossclk - it's trivial and not related to these bindings.

> +
> +  # UART controller node that consumes the clock generated by CMU_PERI
> +  - |
> +    #include <dt-bindings/clock/exynos850.h>
> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +    serial_0: serial@13820000 {
> +        compatible = "samsung,exynos850-uart";
> +        reg = <0x13820000 0x100>;
> +        interrupts = <GIC_SPI 227 IRQ_TYPE_LEVEL_HIGH>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&uart0_pins>;
> +        clocks = <&cmu_peri GOUT_UART_PCLK>, <&cmu_peri GOUT_UART_IPCLK>;
> +        clock-names = "uart", "clk_uart_baud0";

The same, skip it because it is trivial and common with all clock providers.

Also Rob's robot checker complains about it.

Best regards,
Krzysztof