Re: [PATCH RESEND v10 2/3] dt-bindings: hwmon: Support Aspeed g6 PWM TACH Control

From: Rob Herring
Date: Wed Nov 08 2023 - 13:21:41 EST


On Tue, Nov 07, 2023 at 06:50:24PM +0800, Billy Tsai wrote:
> Document the compatible for aspeed,ast2600-pwm-tach device, which can
> support up to 16 PWM outputs and 16 fan tach input.
>
> Signed-off-by: Billy Tsai <billy_tsai@xxxxxxxxxxxxxx>
> ---
> .../bindings/hwmon/aspeed,g6-pwm-tach.yaml | 69 +++++++++++++++++++
> 1 file changed, 69 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml
>
> diff --git a/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml b/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml
> new file mode 100644
> index 000000000000..c615fb10705c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/aspeed,g6-pwm-tach.yaml
> @@ -0,0 +1,69 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +# Copyright (C) 2023 Aspeed, Inc.
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwmon/aspeed,g6-pwm-tach.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: ASPEED G6 PWM and Fan Tach controller
> +
> +maintainers:
> + - Billy Tsai <billy_tsai@xxxxxxxxxxxxxx>
> +
> +description: |
> + The ASPEED PWM controller can support up to 16 PWM outputs.
> + The ASPEED Fan Tacho controller can support up to 16 fan tach input.
> + They are independent hardware blocks, which are different from the
> + previous version of the ASPEED chip.
> +
> +properties:
> + compatible:
> + enum:
> + - aspeed,ast2600-pwm-tach
> +
> + reg:
> + maxItems: 1
> +
> + clocks:
> + maxItems: 1
> +
> + resets:
> + maxItems: 1
> +
> + "#pwm-cells":
> + const: 3
> +
> +patternProperties:
> + "^fan-[0-9]+$":
> + $ref: fan-common.yaml#
> + unevaluatedProperties: false
> + required:
> + - tach-ch
> +
> +required:
> + - reg
> + - clocks
> + - resets
> + - "#pwm-cells"
> + - compatible
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + #include <dt-bindings/clock/aspeed-clock.h>
> + pwm_tach: pwm-tach-controller@1e610000 {
> + compatible = "aspeed,ast2600-pwm-tach";
> + reg = <0x1e610000 0x100>;
> + clocks = <&syscon ASPEED_CLK_AHB>;
> + resets = <&syscon ASPEED_RESET_PWM>;
> + #pwm-cells = <3>;
> +
> + fan-0 {

I assume there's a PWM connection here? How do you know which PWM? You
said the tach channel is independent, so it is not that.

It should not be 0 from 'fan-0' because that's just a meaningless index.

You either need 'pwms' here or you can use 'reg' and the reg value is
the PWM channel.

> + tach-ch = /bits/ 8 <0x0>;
> + };
> +
> + fan-1 {
> + tach-ch = /bits/ 8 <0x1 0x2>;
> + };
> + };
> --
> 2.25.1
>