dt-bindings: interrupt-controller: Add RISC-V advanced PLIC

Add DT bindings document for RISC-V advanced platform level interrupt
controller (APLIC) defined by the RISC-V advanced interrupt architecture
(AIA) specification.
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20240307140307.646078-6-apatel@ventanamicro.com

Documentation/devicetree/bindings/interrupt-controller/riscv,aplic.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/interrupt-controller/riscv,aplic.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RISC-V Advanced Platform Level Interrupt Controller (APLIC)
+
+maintainers:
+  - Anup Patel <anup@brainfault.org>
+
+description:
+  The RISC-V advanced interrupt architecture (AIA) defines an advanced
+  platform level interrupt controller (APLIC) for handling wired interrupts
+  in a RISC-V platform. The RISC-V AIA specification can be found at
+  https://github.com/riscv/riscv-aia.
+
+  The RISC-V APLIC is implemented as hierarchical APLIC domains where all
+  interrupt sources connect to the root APLIC domain and a parent APLIC
+  domain can delegate interrupt sources to it's child APLIC domains. There
+  is one device tree node for each APLIC domain.
+
+allOf:
+  - $ref: /schemas/interrupt-controller.yaml#
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - qemu,aplic
+      - const: riscv,aplic
+
+  reg:
+    maxItems: 1
+
+  interrupt-controller: true
+
+  "#interrupt-cells":
+    const: 2
+
+  interrupts-extended:
+    minItems: 1
+    maxItems: 16384
+    description:
+      Given APLIC domain directly injects external interrupts to a set of
+      RISC-V HARTS (or CPUs). Each node pointed to should be a riscv,cpu-intc
+      node, which has a CPU node (i.e. RISC-V HART) as parent.
+
+  msi-parent:
+    description:
+      Given APLIC domain forwards wired interrupts as MSIs to a AIA incoming
+      message signaled interrupt controller (IMSIC). If both "msi-parent" and
+      "interrupts-extended" properties are present then it means the APLIC
+      domain supports both MSI mode and Direct mode in HW. In this case, the
+      APLIC driver has to choose between MSI mode or Direct mode.
+
+  riscv,num-sources:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 1023
+    description:
+      Specifies the number of wired interrupt sources supported by this
+      APLIC domain.
+
+  riscv,children:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    minItems: 1
+    maxItems: 1024
+    items:
+      maxItems: 1
+    description:
+      A list of child APLIC domains for the given APLIC domain. Each child
+      APLIC domain is assigned a child index in increasing order, with the
+      first child APLIC domain assigned child index 0. The APLIC domain child
+      index is used by firmware to delegate interrupts from the given APLIC
+      domain to a particular child APLIC domain.
+
+  riscv,delegation:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    minItems: 1
+    maxItems: 1024
+    items:
+      items:
+        - description: child APLIC domain phandle
+        - description: first interrupt number of the parent APLIC domain (inclusive)
+        - description: last interrupt number of the parent APLIC domain (inclusive)
+    description:
+      A interrupt delegation list where each entry is a triple consisting
+      of child APLIC domain phandle, first interrupt number of the parent
+      APLIC domain, and last interrupt number of the parent APLIC domain.
+      Firmware must configure interrupt delegation registers based on
+      interrupt delegation list.
+
+dependencies:
+  riscv,delegation: [ "riscv,children" ]
+
+required:
+  - compatible
+  - reg
+  - interrupt-controller
+  - "#interrupt-cells"
+  - riscv,num-sources
+
+anyOf:
+  - required:
+      - interrupts-extended
+  - required:
+      - msi-parent
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    // Example 1 (APLIC domains directly injecting interrupt to HARTs):
+
+    interrupt-controller@c000000 {
+      compatible = "qemu,aplic", "riscv,aplic";
+      interrupts-extended = <&cpu1_intc 11>,
+                            <&cpu2_intc 11>,
+                            <&cpu3_intc 11>,
+                            <&cpu4_intc 11>;
+      reg = <0xc000000 0x4080>;
+      interrupt-controller;
+      #interrupt-cells = <2>;
+      riscv,num-sources = <63>;
+      riscv,children = <&aplic1>, <&aplic2>;
+      riscv,delegation = <&aplic1 1 63>;
+    };
+
+    aplic1: interrupt-controller@d000000 {
+      compatible = "qemu,aplic", "riscv,aplic";
+      interrupts-extended = <&cpu1_intc 9>,
+                            <&cpu2_intc 9>;
+      reg = <0xd000000 0x4080>;
+      interrupt-controller;
+      #interrupt-cells = <2>;
+      riscv,num-sources = <63>;
+    };
+
+    aplic2: interrupt-controller@e000000 {
+      compatible = "qemu,aplic", "riscv,aplic";
+      interrupts-extended = <&cpu3_intc 9>,
+                            <&cpu4_intc 9>;
+      reg = <0xe000000 0x4080>;
+      interrupt-controller;
+      #interrupt-cells = <2>;
+      riscv,num-sources = <63>;
+    };
+
+  - |
+    // Example 2 (APLIC domains forwarding interrupts as MSIs):
+
+    interrupt-controller@c000000 {
+      compatible = "qemu,aplic", "riscv,aplic";
+      msi-parent = <&imsic_mlevel>;
+      reg = <0xc000000 0x4000>;
+      interrupt-controller;
+      #interrupt-cells = <2>;
+      riscv,num-sources = <63>;
+      riscv,children = <&aplic3>;
+      riscv,delegation = <&aplic3 1 63>;
+    };
+
+    aplic3: interrupt-controller@d000000 {
+      compatible = "qemu,aplic", "riscv,aplic";
+      msi-parent = <&imsic_slevel>;
+      reg = <0xd000000 0x4000>;
+      interrupt-controller;
+      #interrupt-cells = <2>;
+      riscv,num-sources = <63>;
+    };
+...