ipxe/src/filo/README.usb

It is from steven james's baremetal in linuxbios util.
yhlu seperate common functions from uhci.c to usb.c and create ohci.c to support ohci.
ohci.c mainly cames from kernel 2.4.22 dirvers/usb/host/usb-ohci.c.
it includes several parts
1. UHCI+OHCI--->USB: privide usb init and usb_control_msg and usb_bulk_msg interface
2. USB_SCSI: bulk only device 
3. USB_X interface to FILO

other changes in Etherboot
1. Add allot2 and forget2, it will produce the required aligned memory.

todo:
1. EHCI support

yhlu 6/2/2004