[RFC v11 2/4] dt-bindings: soc: microchip: document PolarFire SoC's gpio interrupt mux

[Conor Dooley]

From: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>

On PolarFire SoC there are more GPIO interrupts than there are interrupt
lines available on the PLIC, and a runtime configurable mux is used to
decide which interrupts are assigned direct connections to the PLIC &
which are relegated to sharing a line.

Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
---
 .../soc/microchip/microchip,mpfs-irqmux.yaml  | 76 +++++++++++++++++++
 .../microchip,mpfs-mss-top-sysreg.yaml        |  4 +
 2 files changed, 80 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-irqmux.yaml

diff --git a/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-irqmux.yaml b/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-irqmux.yaml
new file mode 100644
index 0000000000000..c8b0de9444dd6
--- /dev/null
+++ b/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-irqmux.yaml
@@ -0,0 +1,76 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/microchip/microchip,mpfs-irqmux.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip Polarfire SoC GPIO Interrupt Mux
+
+maintainers:
+  - Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
+
+description: |
+  There are 3 GPIO controllers on this SoC, of which:
+  - GPIO controller 0 has 14 GPIOs
+  - GPIO controller 1 has 24 GPIOs
+  - GPIO controller 2 has 32 GPIOs
+
+  All GPIOs are capable of generating interrupts, for a total of 70.
+  There are only 41 IRQs available however, so a configurable mux is used to
+  ensure all GPIOs can be used for interrupt generation.
+  38 of the 41 interrupts are in what the documentation calls "direct mode",
+  as they provide an exclusive connection from a GPIO to the PLIC.
+  The 3 remaining interrupts are used to mux the interrupts which do not have
+  a exclusive connection, one for each GPIO controller.
+
+properties:
+  compatible:
+    const: microchip,mpfs-irqmux
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 0
+
+  "#interrupt-cells":
+    const: 1
+
+  interrupt-map-mask:
+    items:
+      - const: 0x7f
+
+  interrupt-map:
+    description: |
+      Specifies the mapping from GPIO interrupt lines to plic interrupts.
+
+      The child interrupt number set in arrays items is computed using the
+      following formula:
+          gpio_bank * 32 + gpio_number
+      with:
+        - gpio_bank: The GPIO bank number
+            - 0 for GPIO0,
+            - 1 for GPIO1,
+            - 2 for GPIO2
+        - gpio_number: Number of the gpio in the bank (0..31)
+    maxItems: 70
+
+required:
+  - compatible
+  - reg
+  - "#address-cells"
+  - "#interrupt-cells"
+  - interrupt-map-mask
+  - interrupt-map
+
+additionalProperties: false
+
+examples:
+  - |
+    interrupt-controller@54 {
+        compatible = "microchip,mpfs-irqmux";
+        reg = <0x54 0x4>;
+        #address-cells = <0>;
+        #interrupt-cells = <1>;
+        interrupt-map-mask = <0xff>;
+    };
diff --git a/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-mss-top-sysreg.yaml b/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-mss-top-sysreg.yaml
index 44e4a50c31554..276d48ba15f01 100644
--- a/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-mss-top-sysreg.yaml
+++ b/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-mss-top-sysreg.yaml
@@ -38,6 +38,10 @@ properties:
       of PolarFire clock/reset IDs.
     const: 1
 
+  interrupt-controller@54:
+    type: object
+    $ref: /schemas/soc/microchip/microchip,mpfs-irqmux.yaml
+
   pinctrl@200:
     type: object
     $ref: /schemas/pinctrl/microchip,mpfs-pinctrl-iomux0.yaml
-- 
2.51.0