USB devices can be represented as two levels of device tree nodes. A device node represents the entire USB device. One or more child interface nodes represent the individual USB interfaces on the device.
Driver binding is achieved by using the compatible name properties. For more information, refer to 220.127.116.11 of the IEEE 1275 USB binding and Writing Device Drivers. A driver can either bind to the entire device and control all the interfaces, or can bind to just one interface. If no vendor or class driver claims the entire device, a generic USB multi-interface driver is bound to the device-level node. This driver attempts to bind drivers to each interface by using compatible names properties, as defined in section 18.104.22.168 of the IEEE 1275 binding specification.
The Solaris USB Architecture (USBA) adheres to the USB 1.1 and USB 2.0 specifications and is part of the Solaris Device Driver Interface (DDI). The USBA model is similar to Sun Common SCSI Architecture (SCSA). As the following figure shows, the USBA is a thin layer that provides a generic USB transport-layer abstraction to client drivers, providing them with services that implement core generic USB functionality.