dt-bindings: usb: Add binding for fcs,fsa4480

The Fairchild/ON Semiconductor FSA4480 Analog Audio switch is used in
USB Type-C configurations for muxing analog audio onto the USB
connector, and as such used to control the SBU signals for altmodes such
as DisplayPort.

Add a binding for this hardware block.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220422222351.1297276-7-bjorn.andersson@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/fcs,fsa4480.yaml

@@ -0,0 +1,72 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/usb/fcs,fsa4480.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: ON Semiconductor Analog Audio Switch
+
+maintainers:
+  - Bjorn Andersson <bjorn.andersson@linaro.org>
+
+properties:
+  compatible:
+    enum:
+      - fcs,fsa4480
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  vcc-supply:
+    description: power supply (2.7V-5.5V)
+
+  mode-switch:
+    description: Flag the port as possible handle of altmode switching
+    type: boolean
+
+  orientation-switch:
+    description: Flag the port as possible handler of orientation switching
+    type: boolean
+
+  port:
+    $ref: /schemas/graph.yaml#/properties/port
+    description:
+      A port node to link the FSA4480 to a TypeC controller for the purpose of
+      handling altmode muxing and orientation switching.
+
+required:
+  - compatible
+  - reg
+  - port
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    i2c13 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        fsa4480@42 {
+          compatible = "fcs,fsa4480";
+          reg = <0x42>;
+
+          interrupts-extended = <&tlmm 2 IRQ_TYPE_LEVEL_LOW>;
+
+          vcc-supply = <&vreg_bob>;
+
+          mode-switch;
+          orientation-switch;
+
+          port {
+            fsa4480_ept: endpoint {
+              remote-endpoint = <&typec_controller>;
+            };
+          };
+        };
+    };
+...