[U-Boot] implement usb gadget ethernet in uboot

hi guys.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. Our board don`t have ethernet chip.So i want to implement gadget ethernet in uboot. Then i can use tftp to download kernel image.

I have implement gadget ethernet in kernel(cdc_subset). But the uboot don`t have gadget framework.how can i implement this feature?Does anyone has this experience?

thank you.