Add mediatek,pnswap boolean property as well as an example for the
MediaTek MT7981 SoC making use of that new property.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 .../arm/mediatek/mediatek,sgmiisys.yaml       | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/mediatek/mediatek,sgmiisys.yaml b/Documentation/devicetree/bindings/arm/mediatek/mediatek,sgmiisys.yaml
index 99ceb08ad7c0..97d4ab70e541 100644
--- a/Documentation/devicetree/bindings/arm/mediatek/mediatek,sgmiisys.yaml
+++ b/Documentation/devicetree/bindings/arm/mediatek/mediatek,sgmiisys.yaml
@@ -23,6 +23,8 @@ properties:
           - enum:
               - mediatek,mt7622-sgmiisys
               - mediatek,mt7629-sgmiisys
+              - mediatek,mt7981-sgmiisys_0
+              - mediatek,mt7981-sgmiisys_1
               - mediatek,mt7986-sgmiisys_0
               - mediatek,mt7986-sgmiisys_1
           - const: syscon
@@ -33,6 +35,10 @@ properties:
   '#clock-cells':
     const: 1
 
+  mediatek,pnswap:
+    description: Invert polarity of the SGMII data lanes
+    type: boolean
+
 required:
   - compatible
   - reg
@@ -51,3 +57,19 @@ examples:
         #clock-cells = <1>;
       };
     };
+  - |
+    soc {
+      #address-cells = <2>;
+      #size-cells = <2>;
+      sgmiisys0: syscon@10060000 {
+        compatible = "mediatek,mt7981-sgmiisys_0", "syscon";
+        reg = <0 0x10060000 0 0x1000>;
+        mediatek,pnswap;
+        #clock-cells = <1>;
+      };
+      sgmiisys1: syscon@10070000 {
+        compatible = "mediatek,mt7981-sgmiisys_1", "syscon";
+        reg = <0 0x10070000 0 0x1000>;
+        #clock-cells = <1>;
+      };
+    };
-- 
2.39.1