dt-bindings: power: reboot: Add Apple Mac SMC Reboot Controller

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.

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Reviewed-by: "Rob Herring (Arm)" <robh@kernel.org>
Signed-off-by: Sven Peter <sven@kernel.org>
Link: https://lore.kernel.org/r/20250610-smc-6-15-v7-2-556cafd771d3@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

Author: svenpeter42

Documentation/devicetree/bindings/power/reset/apple,smc-reboot.yaml

@@ -0,0 +1,40 @@
+# 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@kernel.org>
+
+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
+
+  nvmem-cell-names:
+    items:
+      - const: shutdown_flag
+      - const: boot_stage
+      - const: boot_error_count
+      - const: panic_count
+
+required:
+  - compatible
+  - nvmem-cells
+  - nvmem-cell-names
+
+additionalProperties: false

MAINTAINERS

@@ -2346,6 +2346,7 @@ 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