[U-Boot] How to add new device driver from Linux driver source

Dears,

Our system used u-boot as the boot code, and it would be like to support SD card.

We get the SD controller driver from vendor, it is linux source code.

Do you have any comments or documents about how to port this source code into u-boot source tree.

We would like to build it and try if this can work or should do modify on this source.

Thanks

Jack