dt-bindings: arm: mediatek: document the pcie mirror node on MT7622

This patch adds the pcie mirror document bindings for MT7622 SoC.
The feature is used for intercepting PCIe MMIO access for the WED core
Add related info in mediatek-net bindings.
Signed-off-by: NLorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: NFelix Fietkau <nbd@nbd.name>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/arm/mediatek/mediatek,mt7622-pcie-mirror.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/arm/mediatek/mediatek,mt7622-pcie-mirror.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: MediaTek PCIE Mirror Controller for MT7622
+
+maintainers:
+  - Lorenzo Bianconi <lorenzo@kernel.org>
+  - Felix Fietkau <nbd@nbd.name>
+
+description:
+  The mediatek PCIE mirror provides a configuration interface for PCIE
+  controller on MT7622 soc.
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - mediatek,mt7622-pcie-mirror
+      - const: syscon
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    soc {
+      #address-cells = <2>;
+      #size-cells = <2>;
+      pcie_mirror: pcie-mirror@10000400 {
+        compatible = "mediatek,mt7622-pcie-mirror", "syscon";
+        reg = <0 0x10000400 0 0x10>;
+      };
+    };

Documentation/devicetree/bindings/net/mediatek-net.txt

@@ -48,6 +48,8 @@ Optional properties:
 	various clocks and reset to the system.
 - mediatek,wed: a list of phandles to wireless ethernet dispatch nodes for
 	MT7622 SoC.
+- mediatek,pcie-mirror: phandle to the mediatek pcie-mirror controller for
+	MT7622 SoC.
 
 * Ethernet MAC node