USB dual role


I have mini2440 install qtopia.
I want to use USB host as USB dual role.
1. When mini2440 connect to PC through USB to USB cable it work as
peripheral means i want to transmit serial data to PC through USB host.
2. When Pendriver or any OTG connected to mini2440 it works as host that is
now already working.

How can i use USB host as a USB Dual role?