GPIO giving No access to /dev/mem. Try running as root!

Hi

Followed this site http://wiki.lemaker.org/BananaPro/Pi:GPIO_library#Installation

but unable to blink a single LED on my banana pi m4

It gives the following error

No access to /dev/mem. Try running as root! Tried with sudo and sudo su -i too.

And there is no official documentation as well

Can anybody tell us how to do

Thanks in advance

Very disappointed to see there is absolutely no support for GPIO!!