How to calculate/get gpio number for Sitara AM335x?

Hi,

On this forum, there are some posts on GPIO. I don't know how to get gpio number from its pin. Here is an example:

eg for gpio2_18 will be 82;

e2e.ti.com/.../303278

How to get '82' from 'gpio2_18'? 2 is the bank number?

I have read the wiki below. It looks there is no such information inside.

http://processors.wiki.ti.com/index.php/Linux_PSP_GPIO_Driver_Guide

Anyone can help?

Thanks,