Re: [PATCH RFC 1/2] dt-bindings: pinctrl: Add pinctrl-packed

[Krzysztof Kozlowski <krzk@kernel.org>]

On 13/02/2026 09:17, Billy Tsai wrote:
> Add a Devicetree binding for a generic pin controller where pinmux and/or
> pin configuration are represented as fixed-width fields packed
> sequentially within shared registers.
> 
> The binding targets controllers that are typically exposed as subnodes of
> a syscon node and accessed via regmap-mmio through the parent.
> 
> Signed-off-by: Billy Tsai <billy_tsai@aspeedtech.com>
> ---
>  .../bindings/pinctrl/pinctrl-packed.yaml           | 166 +++++++++++++++++++++
>  1 file changed, 166 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-packed.yaml b/Documentation/devicetree/bindings/pinctrl/pinctrl-packed.yaml
> new file mode 100644
> index 000000000000..dd01ba2fed71
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-packed.yaml
> @@ -0,0 +1,166 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pinctrl/pinctrl-packed.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Generic Pin Controller with Packed-Field Registers
> +
> +maintainers:
> +  - Billy Tsai <billy_tsai@aspeedtech.com>
> +
> +description:
> +  This binding describes pin controller hardware where pinmux and/or
> +  pin configuration fields are represented as fixed-width fields packed
> +  sequentially within shared registers.
> +
> +  Such controllers are commonly embedded within a larger system control
> +  unit (SCU) register block and may be exposed as subnodes of a syscon
> +  device.
> +
> +  Conceptually, this model is related to the pinctrl-single binding,
> +  but instead of describing individual register offsets via
> +  <offset, value, mask> tuples, the hardware provides fixed-width,
> +  per-pin fields packed linearly within shared registers.

Why this cannot be part of pinctrl-single then? Why all these properties
are needed? I imagine that you need them to customize the generic
binding to your device and that would be counter argument - generic
bindings are too generic so people need to grow them with hundreds
properties (see the very simple binding of simple audio card).


> +
> +properties:
> +  compatible:
> +    oneOf:

Drop oneOf

> +      - enum:
> +          - pinctrl-packed
> +          - pinconf-packed
> +
> +  reg:
> +    maxItems: 1
> +
> +  '#pinctrl-cells':
> +    description:
> +      The pinctrl provider uses standard state nodes referenced by pinctrl-N
> +      properties; consumers do not pass per-pin arguments via phandle.
> +    const: 1
> +
> +  pinctrl-packed,function-mask:
> +    description: Mask of the allowed register bits for a single pin.
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +
> +  pinctrl-packed,gpio-range:
> +    description: Optional list of pin base, nr pins & gpio function.
> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +    items:
> +      items:
> +        - description: phandle of a gpio-range node
> +        - description: pin base
> +        - description: number of pins
> +        - description: gpio function
> +
> +patternProperties:
> +  '-pins(-[0-9]+)?$|-pin$':
> +    type: object
> +    additionalProperties: false
> +
> +    properties:
> +      pinctrl-packed,pins:

No, use standard pinctrl properties.

> +        description: Array of pin index and function selector pairs.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +
> +      pinctrl-packed,bias-pullup:
> +        description: Optional bias pull-up configuration.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        maxItems: 4
> +        items:
> +          - description: Input value.
> +          - description: Enabled pull-up bits.
> +          - description: Disabled pull-up bits.
> +          - description: Pull-up mask.
> +        additionalItems: false
> +
> +      pinctrl-packed,bias-pulldown:
> +        description: Optional bias pull-down configuration.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        maxItems: 4
> +        items:
> +          - description: Input value.
> +          - description: Enabled pull-down bits.
> +          - description: Disabled pull-down bits.
> +          - description: Pull-down mask.
> +        additionalItems: false
> +
> +      pinctrl-packed,drive-strength:
> +        description: Optional drive strength configuration.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        maxItems: 2
> +        items:
> +          - description: Drive strength value.
> +          - description: Drive strength mask.
> +        additionalItems: false
> +
> +      pinctrl-packed,input-schmitt:
> +        description: Optional input Schmitt trigger configuration.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        maxItems: 2
> +        items:
> +          - description: Schmitt trigger value.
> +          - description: Schmitt trigger mask.
> +        additionalItems: false
> +
> +      pinctrl-packed,input-schmitt-enable:
> +        description: Optional input Schmitt enable configuration.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        maxItems: 4
> +        items:
> +          - description: Input value.
> +          - description: Enable bits.
> +          - description: Disable bits.
> +          - description: Schmitt mask.
> +        additionalItems: false
> +
> +      pinctrl-packed,low-power-mode:
> +        description: Optional low power mode configuration.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        maxItems: 2
> +        items:
> +          - description: Low power value.
> +          - description: Low power mask.
> +        additionalItems: false
> +
> +      pinctrl-packed,slew-rate:
> +        description: Optional slew rate configuration.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        maxItems: 2
> +        items:
> +          - description: Slew rate value.
> +          - description: Slew rate mask.
> +        additionalItems: false
> +
> +required:
> +  - compatible
> +  - reg
> +  - "#pinctrl-cells"
> +  - pinctrl-packed,function-mask
> +
> +additionalProperties: false
> +
> +allOf:
> +  - $ref: pinctrl.yaml#
> +
> +examples:
> +  - |
> +    syscon@0 {
> +        compatible = "syscon", "simple-mfd";

This is not allowed and you will have warnings here, which means you did
not test the binding correctly (completely). Not even needed here, drop
entire node.

Best regards,
Krzysztof