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+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/interrupt-controller/riscv,imsics.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: RISC-V Incoming MSI Controller (IMSIC)
+
+maintainers:
+ - Anup Patel <anup@brainfault.org>
+
+description: |
+ The RISC-V advanced interrupt architecture (AIA) defines a per-CPU incoming
+ MSI controller (IMSIC) for handling MSIs in a RISC-V platform. The RISC-V
+ AIA specification can be found at https://github.com/riscv/riscv-aia.
+
+ The IMSIC is a per-CPU (or per-HART) device with separate interrupt file
+ for each privilege level (machine or supervisor). The configuration of
+ a IMSIC interrupt file is done using AIA CSRs and it also has a 4KB MMIO
+ space to receive MSIs from devices. Each IMSIC interrupt file supports a
+ fixed number of interrupt identities (to distinguish MSIs from devices)
+ which is same for given privilege level across CPUs (or HARTs).
+
+ The device tree of a RISC-V platform will have one IMSIC device tree node
+ for each privilege level (machine or supervisor) which collectively describe
+ IMSIC interrupt files at that privilege level across CPUs (or HARTs).
+
+ The arrangement of IMSIC interrupt files in MMIO space of a RISC-V platform
+ follows a particular scheme defined by the RISC-V AIA specification. A IMSIC
+ group is a set of IMSIC interrupt files co-located in MMIO space and we can
+ have multiple IMSIC groups (i.e. clusters, sockets, chiplets, etc) in a
+ RISC-V platform. The MSI target address of a IMSIC interrupt file at given
+ privilege level (machine or supervisor) encodes group index, HART index,
+ and guest index (shown below).
+
+ XLEN-1 > (HART Index MSB) 12 0
+ | | | |
+ -------------------------------------------------------------
+ |xxxxxx|Group Index|xxxxxxxxxxx|HART Index|Guest Index| 0 |
+ -------------------------------------------------------------
+
+allOf:
+ - $ref: /schemas/interrupt-controller.yaml#
+ - $ref: /schemas/interrupt-controller/msi-controller.yaml#
+
+properties:
+ compatible:
+ items:
+ - enum:
+ - qemu,imsics
+ - const: riscv,imsics
+
+ reg:
+ minItems: 1
+ maxItems: 16384
+ description:
+ Base address of each IMSIC group.
+
+ interrupt-controller: true
+
+ "#interrupt-cells":
+ const: 0
+
+ msi-controller: true
+
+ "#msi-cells":
+ const: 0
+
+ interrupts-extended:
+ minItems: 1
+ maxItems: 16384
+ description:
+ This property represents the set of CPUs (or HARTs) for which given
+ device tree node describes the IMSIC interrupt files. Each node pointed
+ to should be a riscv,cpu-intc node, which has a CPU node (i.e. RISC-V
+ HART) as parent.
+
+ riscv,num-ids:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 63
+ maximum: 2047
+ description:
+ Number of interrupt identities supported by IMSIC interrupt file.
+
+ riscv,num-guest-ids:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 63
+ maximum: 2047
+ description:
+ Number of interrupt identities are supported by IMSIC guest interrupt
+ file. When not specified it is assumed to be same as specified by the
+ riscv,num-ids property.
+
+ riscv,guest-index-bits:
+ minimum: 0
+ maximum: 7
+ default: 0
+ description:
+ Number of guest index bits in the MSI target address.
+
+ riscv,hart-index-bits:
+ minimum: 0
+ maximum: 15
+ description:
+ Number of HART index bits in the MSI target address. When not
+ specified it is calculated based on the interrupts-extended property.
+
+ riscv,group-index-bits:
+ minimum: 0
+ maximum: 7
+ default: 0
+ description:
+ Number of group index bits in the MSI target address.
+
+ riscv,group-index-shift:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 55
+ default: 24
+ description:
+ The least significant bit position of the group index bits in the
+ MSI target address.
+
+required:
+ - compatible
+ - reg
+ - interrupt-controller
+ - msi-controller
+ - "#msi-cells"
+ - interrupts-extended
+ - riscv,num-ids
+
+unevaluatedProperties: false
+
+examples:
+ - |
+ // Example 1 (Machine-level IMSIC files with just one group):
+
+ interrupt-controller@24000000 {
+ compatible = "qemu,imsics", "riscv,imsics";
+ interrupts-extended = <&cpu1_intc 11>,
+ <&cpu2_intc 11>,
+ <&cpu3_intc 11>,
+ <&cpu4_intc 11>;
+ reg = <0x28000000 0x4000>;
+ interrupt-controller;
+ #interrupt-cells = <0>;
+ msi-controller;
+ #msi-cells = <0>;
+ riscv,num-ids = <127>;
+ };
+
+ - |
+ // Example 2 (Supervisor-level IMSIC files with two groups):
+
+ interrupt-controller@28000000 {
+ compatible = "qemu,imsics", "riscv,imsics";
+ interrupts-extended = <&cpu1_intc 9>,
+ <&cpu2_intc 9>,
+ <&cpu3_intc 9>,
+ <&cpu4_intc 9>;
+ reg = <0x28000000 0x2000>, /* Group0 IMSICs */
+ <0x29000000 0x2000>; /* Group1 IMSICs */
+ interrupt-controller;
+ #interrupt-cells = <0>;
+ msi-controller;
+ #msi-cells = <0>;
+ riscv,num-ids = <127>;
+ riscv,group-index-bits = <1>;
+ riscv,group-index-shift = <24>;
+ };
+...