[RFC PATCH v3 1/2] dt-bindings: usb: snps,dwc3: describe two connectors sharing one HS bus

[Qianhui Xu]

Two connectors can share the High Speed D+/D- pair of a single DWC3
controller, with a GPIO selecting which one is connected.  Super Speed
lanes stay per connector.

Describe that in snps,dwc3-common.yaml:

  - port-select-gpios selects which connector drives the shared HS bus;
  - the shared HS bus is port@0 with two numbered endpoints, endpoint@0
    and endpoint@1, so that "ports" keeps describing the controller's own
    buses as the graph bindings expect;
  - each endpoint carries "mux-state", the port-select level of that
    connector, and "usb-role-switch" to declare that this connector has
    its own role switch input.

When port-select-gpios is absent the endpoint properties are rejected,
so existing single-connector descriptions are unaffected.  The two
mux-state values are constrained to be complementary.

Signed-off-by: Qianhui Xu <xiaqinghuan@xxxxxxxxxxxxxxxx>
---
 .../bindings/usb/snps,dwc3-common.yaml        | 109 +++++++++++++++++-
 1 file changed, 108 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3-common.yaml b/Documentation/devicetree/bindings/usb/snps,dwc3-common.yaml
index 6c0b8b653..6b06b0027 100644
--- a/Documentation/devicetree/bindings/usb/snps,dwc3-common.yaml
+++ b/Documentation/devicetree/bindings/usb/snps,dwc3-common.yaml
@@ -13,6 +13,38 @@ description:
   Defines the properties of the DWC3 core as being embedded in either an
   vendor-specific implementation or as a standalone component.
 
+$defs:
+  hs-endpoint:
+    $ref: /schemas/graph.yaml#/$defs/endpoint-base
+    unevaluatedProperties: false
+
+    properties:
+      usb-role-switch:
+        type: boolean
+        description:
+          This connector endpoint has its own USB role switch. The switch is
+          registered against this endpoint and looked up with
+          usb_role_switch_at_endpoint().
+
+      mux-state:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        enum: [0, 1]
+        description:
+          Logical level of the port-select GPIO which connects this
+          connector to the shared High Speed data bus.
+
+    dependentRequired:
+      usb-role-switch: [mux-state]
+      mux-state: [usb-role-switch]
+
+  hs-port:
+    $ref: /schemas/graph.yaml#/$defs/port-base
+    unevaluatedProperties: false
+
+    patternProperties:
+      '^endpoint@[01]$':
+        $ref: '#/$defs/hs-endpoint'
+
 allOf:
   - $ref: usb-drd.yaml#
   - if:
@@ -26,8 +58,83 @@ allOf:
       $ref: usb.yaml#
     else:
       $ref: usb-xhci.yaml#
+  - if:
+      required: [port-select-gpios]
+    then:
+      required: [dr_mode, ports]
+      properties:
+        dr_mode:
+          const: otg
+        ports:
+          required: [port@0]
+          properties:
+            port@0:
+              required: ['#address-cells', '#size-cells', endpoint@0, endpoint@1]
+              properties:
+                endpoint@0:
+                  required: [usb-role-switch, mux-state]
+                endpoint@1:
+                  required: [usb-role-switch, mux-state]
+    else:
+      properties:
+        ports:
+          properties:
+            port@0:
+              patternProperties:
+                '^endpoint@[01]$':
+                  properties:
+                    usb-role-switch: false
+                    mux-state: false
+  - if:
+      properties:
+        ports:
+          properties:
+            port@0:
+              properties:
+                endpoint@0:
+                  properties:
+                    mux-state:
+                      const: 0
+    then:
+      properties:
+        ports:
+          properties:
+            port@0:
+              properties:
+                endpoint@1:
+                  properties:
+                    mux-state:
+                      const: 1
+  - if:
+      properties:
+        ports:
+          properties:
+            port@0:
+              properties:
+                endpoint@1:
+                  properties:
+                    mux-state:
+                      const: 0
+    then:
+      properties:
+        ports:
+          properties:
+            port@0:
+              properties:
+                endpoint@0:
+                  properties:
+                    mux-state:
+                      const: 1
 
 properties:
+  port-select-gpios:
+    maxItems: 1
+    description:
+      Selects which of the two connectors drives the controller's shared High
+      Speed data bus. Each connector is described by a numbered endpoint of
+      "port@0" that carries its own role-switch input and the "mux-state"
+      level selecting it.
+
   extcon:
     maxItems: 1
     deprecated: true
@@ -411,7 +518,7 @@ properties:
 
     properties:
       port@0:
-        $ref: /schemas/graph.yaml#/properties/port
+        $ref: '#/$defs/hs-port'
         description: High Speed (HS) data bus.
 
       port@1:
-- 
2.53.0