Re: [v3 1/2] dt-bindings: Add bindings for aspeed pwm-tach and pwm.

[Rob Herring <robh@kernel.org>]

On Thu, May 06, 2021 at 02:10:49PM +0800, Billy Tsai wrote:
> This patch adds device bindings for aspeed pwm-tach device which is a
> multi-function device include pwn and tach function and pwm device which
> should be the sub-node of pwm-tach device.
> 
> Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
> ---
>  .../bindings/mfd/aspeed,ast2600-pwm-tach.yaml | 55 +++++++++++++++++++
>  .../bindings/pwm/aspeed,ast2600-pwm.yaml      | 41 ++++++++++++++
>  2 files changed, 96 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
>  create mode 100644 Documentation/devicetree/bindings/pwm/aspeed,ast2600-pwm.yaml
> 
> diff --git a/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
> new file mode 100644
> index 000000000000..9626bbd50acd
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/aspeed,ast2600-pwm-tach.yaml
> @@ -0,0 +1,55 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (C) 2021 ASPEED, Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mfd/aspeed,ast2600-pwm-tach.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: PWM Tach controller Device Tree Bindings
> +
> +description: |
> +  The PWM Tach controller is represented as a multi-function device which
> +  includes:
> +    PWM
> +    Tach
> +
> +maintainers:
> +  - Billy Tsai <billy_tsai@aspeedtech.com>
> +
> +properties:
> +  compatible:
> +    items:
> +      - enum:
> +          - aspeed,ast2600-pwm-tach
> +      - const: syscon
> +      - const: simple-mfd
> +  reg:
> +    maxItems: 1
> +  clocks:
> +    maxItems: 1
> +  resets:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - resets
> +
> +additionalProperties:
> +  type: object
> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/ast2600-clock.h>
> +    pwm_tach: pwm_tach@1e610000 {
> +      compatible = "aspeed,ast2600-pwm-tach", "syscon", "simple-mfd";
> +      reg = <0x1e610000 0x100>;
> +      clocks = <&syscon ASPEED_CLK_AHB>;
> +      resets = <&syscon ASPEED_RESET_PWM>;
> +
> +      pwm: pwm {
> +        compatible = "aspeed,ast2600-pwm";
> +        #pwm-cells = <3>;

There's no need for a child node here. Just put #pwm-cells in the 
parent node.

Of course this all looks incomplete if you ever plan to hook up fans and 
have more than 1 PWM and Tach signal.

> +      };
> +    };

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