dt-bindings: can: fsl,flexcan: add fsl,scu-index property to indicate a resource

For SoCs with SCU support, need setup stop mode via SCU firmware, so this
property can help indicate a resource in SCU firmware.
Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Link: https://lore.kernel.org/r/20201106105627.31061-3-qiangqing.zhang@nxp.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/fsl,flexcan.yaml

@@ -110,6 +110,16 @@ properties:
     description:
       Enable CAN remote wakeup.
 
+  fsl,scu-index:
+    description: |
+      The scu index of CAN instance.
+      For SoCs with SCU support, need setup stop mode via SCU firmware, so this
+      property can help indicate a resource. It supports up to 3 CAN instances
+      now.
+    $ref: /schemas/types.yaml#/definitions/uint8
+    minimum: 0
+    maximum: 2
+
 required:
   - compatible
   - reg
@@ -137,4 +147,5 @@ examples:
         clocks = <&clks 1>, <&clks 2>;
         clock-names = "ipg", "per";
         fsl,stop-mode = <&gpr 0x34 28>;
+        fsl,scu-index = /bits/ 8 <1>;
     };