[U-Boot] tftp download with USB vitrual ethnet driver

Hi，all, I’m am new guy from China, and nice to meet all of yours. These days we use u-boot in out Linux Project base on our SOC chip, and we found it’s not convenient to download kernel image because our board have no ether-net chip, only USB and UART. Linux-2.6.21 etc, support USB CDC subnet(Boot Loader OBject), so if we write a USB device driver and a virtual Ethernet card driver over it , we can realize TFTP download with USB. Now we have test successfully in our project, if necessary I’m very glad to contribute it~ Regards, Gongyibin