Introduction
============

Gadget serial driver is divided into two parts.
1. f_serial.c : Interacts with USB Gadget Layer
2. u_serial.c : Interacts with TTY Layer

Gadget smd driver adds capability to interact with smd layer in
case modem device is inter-connected with smd interface.

S/W Description
===============
Gadget smd driver is a simple bridge driver between usb serial
gadget and smd abstraction layer. It registers with smd
abstraction layer with  notification call back and provides
USB connect/disconnect call backs usb gadget serial driver.


S/W Control Flow:
=================
USB SMD driver registers w/ SMD driver and provides notification
call back. SMD Driver calls this call back whenever DATA is available
to read, buffer is available to write or modem control signals changed.
Upon receiving notification from SMD driver, USB driver appropriately
schedules read/write works. In case of control singals, USB driver
notifies gadget component with changed control information.