Tested on Zynq SOC ARM core, but crashes on amd64 Intel CPU.

For testing, cross-compile the kernel module (make) and the userspace application (arm-linux-gcc -o mymmap_userspace mymmap_userspace.c assuming the Buildroot compiler direction output/host/usr/bin is in the PATH), and on the Redpitaya:

mknod /dev/mydev c 91 0
insmod mymmap.ko
./mymmap_userspace