In This Chapter
Bootstrap Essentials: Class Drivers
Class Driver: Design
Simple Composite Class Driver: Loopback
Universal serial bus (USB) devices are often referred to along with the functionality they support, such as USB audio device or USB storage device. The USB device’s functionality is implemented in the class driver layer. These classes are defined by the USB working group and are available in http://www.usb.org/developers/devclass_docs#approved. Sometimes a device can support more than one functional driver and is referred to as a composite device.
Linux supports simple functional drivers that provide a single functionality, such as mass storage devices. Lately, the Linux gadget framework has introduced a composite ...