microblaze: Add architectural support for USB EHCI host controllers

Add architectural support for USB EHCI host controllers. It has been tested
using the USB EHCI host controller from Xilinx Inc., using both High Speed
devices and Full Speed devices.

Signed-off-by: Julie Zhu <julie.zhu@xilinx.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>
3 files changed