libusbK is a complete driver/library solution for vendor class usb device interfaces. If you are a usb developers or usb device manufacturer seeking a driver solution for a new USB widget then libusbK could be for you.
https://github.com/mcuee/libusbk/
http://sourceforge.net/projects/libusbk/
http://libusbk.sourceforge.net/UsbK3/usbk_about.html
http://libusbk.sourceforge.net/UsbK3/index.html
Dual license with New BSD option and GPL option. The New BSD Option will facilitate the WHQL certification now that Microsoft has added "excluded license" to the WLK license.
Many examples are provided for the library users to develop their own applications. https://github.com/mcuee/libusbk/tree/master/libusbK/examples