linux-kernel - Re: [PATCH v4 2/9] dt-bindings: power: reboot: Add Apple Mac SMC Reboot Controller

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Message-ID: <aB3_GaSrJFKgxNXO@blossom>
Date: Fri, 9 May 2025 09:11:53 -0400
From: Alyssa Rosenzweig <alyssa@...enzweig.io>
To: sven@...npeter.dev
Cc: Janne Grunau <j@...nau.net>, Neal Gompa <neal@...pa.dev>,
	Hector Martin <marcan@...can.st>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Sebastian Reichel <sre@...nel.org>, Lee Jones <lee@...nel.org>,
	Marc Zyngier <maz@...nel.org>,
	"Russell King (Oracle)" <rmk+kernel@...linux.org.uk>,
	asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v4 2/9] dt-bindings: power: reboot: Add Apple Mac SMC
 Reboot Controller

Reviewed-by: Alyssa Rosenzweig <alyssa@...enzweig.io>

Le Sat , May 03, 2025 at 10:06:49AM +0000, Sven Peter via B4 Relay a écrit :
> From: Sven Peter <sven@...npeter.dev>
> 
> On Apple Silicon machines a clean shutdown or reboot requires
> talking to SMC and writing to NVMEM cells. Add a binding for
> this MFD sub-device.
> 
> Signed-off-by: Sven Peter <sven@...npeter.dev>
> ---
>  .../bindings/power/reset/apple,smc-reboot.yaml     | 52 ++++++++++++++++++++++
>  MAINTAINERS                                        |  1 +
>  2 files changed, 53 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/power/reset/apple,smc-reboot.yaml b/Documentation/devicetree/bindings/power/reset/apple,smc-reboot.yaml
> new file mode 100644
> index 0000000000000000000000000000000000000000..e55e524914c2f57f7acf239fdefcbdc7a993b69f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/reset/apple,smc-reboot.yaml
> @@ -0,0 +1,52 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/power/reset/apple,smc-reboot.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Apple SMC Reboot Controller
> +
> +description: |
> +  The Apple System Management Controller (SMC) provides reboot functionality
> +  on Apple Silicon SoCs. It uses NVMEM cells to store and track various
> +  system state information related to boot, shutdown, and panic events.
> +
> +maintainers:
> +  - Sven Peter <sven@...npeter.dev>
> +
> +properties:
> +  compatible:
> +    const: apple,smc-reboot
> +
> +  nvmem-cells:
> +    items:
> +      - description: Flag indicating shutdown (as opposed to reboot)
> +      - description: Stage at which the boot process stopped (0x30 for normal boot)
> +      - description: Counter for boot errors
> +      - description: Counter for system panics
> +      - description: Power management settings
> +
> +  nvmem-cell-names:
> +    items:
> +      - const: shutdown_flag
> +      - const: boot_stage
> +      - const: boot_error_count
> +      - const: panic_count
> +      - const: pm_setting
> +
> +required:
> +  - compatible
> +  - nvmem-cells
> +  - nvmem-cell-names
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    reboot {
> +      compatible = "apple,smc-reboot";
> +      nvmem-cells = <&shutdown_flag>, <&boot_stage>,
> +                    <&boot_error_count>, <&panic_count>, <&pm_setting>;
> +      nvmem-cell-names = "shutdown_flag", "boot_stage",
> +                         "boot_error_count", "panic_count", "pm_setting";
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7f91f0225133490607ba0d79ad4225892ef31a66..d85d9d9065db4dc5869788f8a81d9d9a425d7ce3 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2282,6 +2282,7 @@ F:	Documentation/devicetree/bindings/nvmem/apple,spmi-nvmem.yaml
>  F:	Documentation/devicetree/bindings/pci/apple,pcie.yaml
>  F:	Documentation/devicetree/bindings/pinctrl/apple,pinctrl.yaml
>  F:	Documentation/devicetree/bindings/power/apple*
> +F:	Documentation/devicetree/bindings/power/reset/apple,smc-reboot.yaml
>  F:	Documentation/devicetree/bindings/pwm/apple,s5l-fpwm.yaml
>  F:	Documentation/devicetree/bindings/spi/apple,spi.yaml
>  F:	Documentation/devicetree/bindings/spmi/apple,spmi.yaml
> 
> -- 
> 2.34.1
> 
>