作者：华清远见嵌入式学院。《Linux设备驱动开发详解》（08&09年度畅销榜TOP50）第20章、USB主机与设备驱动。在Linux系统中，提供了主机侧和设备侧视角的USB驱动框架，本章主要讲解从主机侧角度看到的USB主机控制器驱动和设备驱动。20.1节给出了Linux系统中USB驱动的整体视图，讲解了Linux中主机侧和设备侧角度的USB驱动层次。从主机侧的角度而言，需要编写的USB驱动程序包括主机控制器驱动和设备驱动两类，USB主机控制器驱动程序控制插入其中的USB设备，而USB设备驱动程序控制该设备如何作为从设备与主机通信。本章20.2节分析了USB主机控制器驱动的结构并给出实例，20.3节讲解了USB设备驱动的结构及其设备请求块处理过程，并分析了USB设备驱动的骨架程序，20.4节则给出了Linux设备驱动的实例。20.1节与20.2～20.4节是整体与部分的关系，20.2节与20.3～20.4节是并列关系。-Author: HuaQing vision embedded institute. The Linux device driver development "(08 and 09 sep TOP50) annual list of best-selling chapter 20, USB host and device drivers. In Linux system, provides mainframe side and equipment from the perspective of the USB driver frame, this chapter covers from the host side view in the USB host controller drives and device drivers. Section 20.1 Linux system are given in the overall view, USB driver explained Linux host side and equipment of the Angle USB driver level. From the host in the view of side, need to write the USB drivers including host controller drives and device driver two kinds, USB host controller driver control inserted into USB devices, and USB device driver control the equipment from the equipment and how to as host of communication. This chapter section 20.2 analysis the USB host controller and the structure of the driver