Hi,
You can run source_sync.sh to get the source code. Or download this package:
Jetson Linux Release 36.4.4 | NVIDIA Developer
Driver Package (BSP) Sources
Here is an example of kernel customization:
No data from Joystick Logitech-f710 - #10 by DaneLLL
Because you need to revise device tree, you would need to do the steps Building the DTBs(not do in the example since we use developer kit and can use the default files)