dt-bindings: arm: apple: Add apple,pmgr binding

The PMGR block in Apple Silicon SoCs is responsible for SoC power
management. There are two PMGRs in T8103, with different register
layouts but compatible registers. In order to support this as well
as future SoC generations with backwards-compatible registers, we
declare these blocks as syscons and bind to individual registers
in child nodes. Each register controls one SoC device.

The respective apple compatibles are defined in case device-specific
quirks are necessary in the future, but currently these nodes are
expected to be bound by the generic syscon driver.

Reviewed-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hector Martin <marcan@marcan.st>

Documentation/devicetree/bindings/arm/apple/apple,pmgr.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/arm/apple/apple,pmgr.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple SoC Power Manager (PMGR)
+
+maintainers:
+  - Hector Martin <marcan@marcan.st>
+
+description: |
+  Apple SoCs include PMGR blocks responsible for power management,
+  which can control various clocks, resets, power states, and
+  performance features. This node represents the PMGR as a syscon,
+  with sub-nodes representing individual features.
+
+properties:
+  $nodename:
+    pattern: "^power-management@[0-9a-f]+$"
+
+  compatible:
+    items:
+      - enum:
+          - apple,t8103-pmgr
+          - apple,t6000-pmgr
+      - const: apple,pmgr
+      - const: syscon
+      - const: simple-mfd
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+patternProperties:
+  "power-controller@[0-9a-f]+$":
+    description:
+      The individual power management domains within this controller
+    type: object
+    $ref: /power/apple,pmgr-pwrstate.yaml#
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        power-management@23b700000 {
+            compatible = "apple,t8103-pmgr", "apple,pmgr", "syscon", "simple-mfd";
+            #address-cells = <1>;
+            #size-cells = <1>;
+            reg = <0x2 0x3b700000 0x0 0x14000>;
+
+            ps_sio: power-controller@1c0 {
+                compatible = "apple,t8103-pmgr-pwrstate", "apple,pmgr-pwrstate";
+                reg = <0x1c0 8>;
+                #power-domain-cells = <0>;
+                #reset-cells = <0>;
+                label = "sio";
+                apple,always-on;
+            };
+
+            ps_uart_p: power-controller@220 {
+                compatible = "apple,t8103-pmgr-pwrstate", "apple,pmgr-pwrstate";
+                reg = <0x220 8>;
+                #power-domain-cells = <0>;
+                #reset-cells = <0>;
+                label = "uart_p";
+                power-domains = <&ps_sio>;
+            };
+
+            ps_uart0: power-controller@270 {
+                compatible = "apple,t8103-pmgr-pwrstate", "apple,pmgr-pwrstate";
+                reg = <0x270 8>;
+                #power-domain-cells = <0>;
+                #reset-cells = <0>;
+                label = "uart0";
+                power-domains = <&ps_uart_p>;
+            };
+        };
+
+        power-management@23d280000 {
+            compatible = "apple,t8103-pmgr", "apple,pmgr", "syscon", "simple-mfd";
+            #address-cells = <1>;
+            #size-cells = <1>;
+            reg = <0x2 0x3d280000 0x0 0xc000>;
+
+            ps_aop_filter: power-controller@4000 {
+                compatible = "apple,t8103-pmgr-pwrstate", "apple,pmgr-pwrstate";
+                reg = <0x4000 8>;
+                #power-domain-cells = <0>;
+                #reset-cells = <0>;
+                label = "aop_filter";
+            };
+
+            ps_aop_base: power-controller@4010 {
+                compatible = "apple,t8103-pmgr-pwrstate", "apple,pmgr-pwrstate";
+                reg = <0x4010 8>;
+                #power-domain-cells = <0>;
+                #reset-cells = <0>;
+                label = "aop_base";
+                power-domains = <&ps_aop_filter>;
+            };
+
+            ps_aop_shim: power-controller@4038 {
+                compatible = "apple,t8103-pmgr-pwrstate", "apple,pmgr-pwrstate";
+                reg = <0x4038 8>;
+                #power-domain-cells = <0>;
+                #reset-cells = <0>;
+                label = "aop_shim";
+                power-domains = <&ps_aop_base>;
+            };
+
+            ps_aop_uart0: power-controller@4048 {
+                compatible = "apple,t8103-pmgr-pwrstate", "apple,pmgr-pwrstate";
+                reg = <0x4048 8>;
+                #power-domain-cells = <0>;
+                #reset-cells = <0>;
+                label = "aop_uart0";
+                power-domains = <&ps_aop_shim>;
+            };
+        };
+    };