linux-kernel - Re: [PATCH v2 3/8] dt-bindings: power: Add apple,pmgr-pwrstate binding

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Message-ID: <YXhInb5kWO15YL7W@robh.at.kernel.org>
Date:   Tue, 26 Oct 2021 13:27:41 -0500
From:   Rob Herring <robh@...nel.org>
To:     Hector Martin <marcan@...can.st>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Marc Zyngier <maz@...nel.org>, Arnd Bergmann <arnd@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Johan Hovold <johan@...nel.org>, devicetree@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, linux-serial@...r.kernel.org,
        Mark Kettenis <kettenis@...nbsd.org>
Subject: Re: [PATCH v2 3/8] dt-bindings: power: Add apple,pmgr-pwrstate
 binding

On Mon, Oct 25, 2021 at 11:47:13PM +0900, Hector Martin wrote:
> This syscon child node represents a single SoC device controlled by the
> PMGR block. This layout allows us to declare all device power state
> controls (power/clock gating and reset) in the device tree, including
> dependencies, instead of hardcoding it into the driver. The register
> layout is uniform.
> 
> Each pmgr-pwrstate node provides genpd and reset features, to be
> consumed by downstream device nodes.
> 
> Future SoCs are expected to use backwards compatible registers, and the
> "apple,pmgr-pwrstate" represents any such interfaces (possibly with
> additional features gated by the more specific compatible), allowing
> them to be bound without driver updates. If a backwards incompatible
> change is introduced in future SoCs, it will require a new compatible,
> such as "apple,pmgr-pwrstate-v2".
> 
> Reviewed-by: Mark Kettenis <kettenis@...nbsd.org>
> Signed-off-by: Hector Martin <marcan@...can.st>
> ---
>  .../bindings/power/apple,pmgr-pwrstate.yaml   | 69 +++++++++++++++++++
>  1 file changed, 69 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power/apple,pmgr-pwrstate.yaml
> 
> diff --git a/Documentation/devicetree/bindings/power/apple,pmgr-pwrstate.yaml b/Documentation/devicetree/bindings/power/apple,pmgr-pwrstate.yaml
> new file mode 100644
> index 000000000000..010f8b641304
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/apple,pmgr-pwrstate.yaml
> @@ -0,0 +1,69 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/power/apple,pmgr-pwrstate.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple SoC PMGR Power States
> +
> +maintainers:
> +  - Hector Martin <marcan@...can.st>
> +
> +allOf:
> +  - $ref: "power-domain.yaml#"
> +
> +description: |
> +  Apple SoCs include a PMGR block responsible for power management,
> +  which can control various clocks, resets, power states, and
> +  performance features. This binding describes the device power
> +  state registers, which control power states and resets.
> +
> +  Each instance of a power controller within the PMGR syscon node
> +  represents a generic power domain provider, as documented in
> +  Documentation/devicetree/bindings/power/power-domain.yaml.
> +  The provider controls a single SoC block. The power hierarchy is
> +  represented via power-domains relationships between these nodes.
> +
> +  See Documentation/devicetree/bindings/arm/apple/apple,pmgr.yaml
> +  for the top-level PMGR node documentation.
> +
> +properties:
> +  compatible:
> +    items:
> +      - enum:
> +          - apple,t8103-pmgr-pwrstate
> +      - const: apple,pmgr-pwrstate
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#power-domain-cells":
> +    const: 0
> +
> +  "#reset-cells":
> +    const: 0
> +
> +  power-domains:
> +    description:
> +      Reference to parent power domains. A domain may have multiple parents,
> +      and all will be powered up when it is powered.
> +    minItems: 1
> +
> +  label:
> +    description: |
> +      Specifies the name of the SoC domain being controlled. This is used to
> +      name the power/reset domains.
> +
> +  apple,always-on:
> +    description: |

Can drop '|' on these too. Otherwise,

Reviewed-by: Rob Herring <robh@...nel.org>

> +      Forces this power domain to always be powered up.
> +    type: boolean
> +
> +required:
> +  - compatible
> +  - reg
> +  - "#power-domain-cells"
> +  - "#reset-cells"
> +  - label
> +
> +additionalProperties: false
> -- 
> 2.33.0
> 
>