How can fast read GPIO status at TX1 r28.2?
Don’t know if this will give you what you want, but this is a similar topic:
https://devtalk.nvidia.com/default/topic/995395/jetson-tk1/fast-access-to-gpio/
The kernel versions differ, so I’m not sure if it is 100% applicable, but I do know at least parts of it are exact matches to use on R28.2.