Driver for an usb RS232 convertor


I’am building a driver for an usb RS232 convertor. I would like to know if
it is possible to do this without changing the io_char librairy and using
io_open, io_close, io_write and io_read.
In fact, I tried to do this just in changing the devc/8250 librairy (for
RS232). But I have a problem in trying to use stty and echo (to send datas)
with my driver.
#stty </devc/ser/usbser1 => this function never stop.
#echo “data” >/devc/ser/usbser1 => so I can’t use this function.

Thank you for the help.