Search For a dummy usb kernel module

Hello,..
i am trieng to learn how to write usb comunication with gadets.
i thought about starting and working with gadget driver but then i had
been told that this module need to actually see a device .

so i am searching for some program (it will be better if it be in user
space but i don't mind if not) that will tell the kernel that a new
device had been connected to the kernel (ill be happy to have the
abuilty to change that values of product ID and Vendor ID )

also another abiulty that is needed that i could echo a msg to that
module.

lets call that kernel module dummyusb
so i will do
#modprove dummyusb
echo 1>/sys/bus/usb/drivers/dummyusb/state

and that will resolt in the module move to state 1.

for now im reading libusb documentation but anything more intresting
is more then welcome ..


P.s sorry for the spelling .
i have started to put all my studies about usb on my personal blog :

http://bsh83.blogspot.com/search/label/USB

.