xlnx-versal: Connect Xilinx VERSAL CANFD controllers

Connect CANFD0 and CANFD1 on the Versal-virt machine and update xlnx-versal-virt
document with CANFD command line examples.

Signed-off-by: Vikram Garhwal <vikram.garhwal@amd.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Francisco Iglesias <frasse.iglesias@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/system/arm/xlnx-versal-virt.rst

@@ -34,6 +34,7 @@ Implemented devices:
 - DDR memory
 - BBRAM (36 bytes of Battery-backed RAM)
 - eFUSE (3072 bytes of one-time field-programmable bit array)
+- 2 CANFDs
 
 QEMU does not yet model any other devices, including the PL and the AI Engine.
 
@@ -224,3 +225,33 @@ To use a different index value, N, from default of 1, add:
 
   Better yet, do not use actual product data when running guest image
   on this Xilinx Versal Virt board.
+
+Using CANFDs for Versal Virt
+""""""""""""""""""""""""""""
+Versal CANFD controller is developed based on SocketCAN and QEMU CAN bus
+implementation. Bus connection and socketCAN connection for each CAN module
+can be set through command lines.
+
+To connect both CANFD0 and CANFD1 on the same bus:
+
+.. code-block:: bash
+
+    -object can-bus,id=canbus -machine canbus0=canbus -machine canbus1=canbus
+
+To connect CANFD0 and CANFD1 to separate buses:
+
+.. code-block:: bash
+
+    -object can-bus,id=canbus0 -object can-bus,id=canbus1 \
+    -machine canbus0=canbus0 -machine canbus1=canbus1
+
+The SocketCAN interface can connect to a Physical or a Virtual CAN interfaces on
+the host machine. Please check this document to learn about CAN interface on
+Linux: docs/system/devices/can.rst
+
+To connect CANFD0 and CANFD1 to host machine's CAN interface can0:
+
+.. code-block:: bash
+
+    -object can-bus,id=canbus -machine canbus0=canbus -machine canbus1=canbus
+    -object can-host-socketcan,id=canhost0,if=can0,canbus=canbus