dt-bindings: net: dsa: mediatek,mt7530: add mediatek,mt7988-switch

Add documentation for the built-in switch which can be found in the
MediaTek MT7988 SoC.
Signed-off-by: NDaniel Golle <daniel@makrotopia.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/mediatek,mt7530.yaml

@@ -11,16 +11,23 @@ maintainers:
   - Landen Chao <Landen.Chao@mediatek.com>
   - DENG Qingfang <dqfext@gmail.com>
   - Sean Wang <sean.wang@mediatek.com>
+  - Daniel Golle <daniel@makrotopia.org>
 
 description: |
-  There are two versions of MT7530, standalone and in a multi-chip module.
+  There are three versions of MT7530, standalone, in a multi-chip module and
+  built-into a SoC.
 
   MT7530 is a part of the multi-chip module in MT7620AN, MT7620DA, MT7620DAN,
   MT7620NN, MT7621AT, MT7621DAT, MT7621ST and MT7623AI SoCs.
 
+  The MT7988 SoC comes with a built-in switch similar to MT7531 as well as four
+  Gigabit Ethernet PHYs. The switch registers are directly mapped into the SoC's
+  memory map rather than using MDIO. The switch got an internally connected 10G
+  CPU port and 4 user ports connected to the built-in Gigabit Ethernet PHYs.
+
   MT7530 in MT7620AN, MT7620DA, MT7620DAN and MT7620NN SoCs has got 10/100 PHYs
   and the switch registers are directly mapped into SoC's memory map rather than
-  using MDIO. The DSA driver currently doesn't support this.
+  using MDIO. The DSA driver currently doesn't support MT7620 variants.
 
   There is only the standalone version of MT7531.
 
@@ -81,6 +88,10 @@ properties:
           Multi-chip module MT7530 in MT7621AT, MT7621DAT and MT7621ST SoCs
         const: mediatek,mt7621
 
+      - description:
+          Built-in switch of the MT7988 SoC
+        const: mediatek,mt7988-switch
+
   reg:
     maxItems: 1
 
@@ -268,6 +279,17 @@ allOf:
       required:
         - mediatek,mcm
 
+  - if:
+      properties:
+        compatible:
+          const: mediatek,mt7988-switch
+    then:
+      $ref: "#/$defs/mt7530-dsa-port"
+      properties:
+        gpio-controller: false
+        mediatek,mcm: false
+        reset-names: false
+
 unevaluatedProperties: false
 
 examples: