u-boot/doc/README.usb

/*
 * (C) Copyright 2001
 * Denis Peter, MPL AG Switzerland
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 *
 */

USB Support for PIP405 and MIP405 (UHCI)
========================================

The USB support is implemented on the base of the UHCI Host
controller.

Currently supported are USB Hubs, USB Keyboards, USB Floppys, USB
flash sticks and USB network adaptors.
Tested with a TEAC Floppy TEAC FD-05PUB and Chicony KU-8933 Keyboard.

How it works:
-------------

The USB (at least the USB UHCI) needs a frame list (4k), transfer
descripor and queue headers which are all located in the main memory.
The UHCI allocates every milisecond the PCI bus and reads the current
frame pointer. This may cause to crash the OS during boot. So the USB
_MUST_ be stopped during OS boot. This is the reason, why the USB is
NOT automatically started during start-up. If someone needs the USB
he has to start it and should therefore be aware that he had to stop
it before booting the OS.

For USB keyboards this can be done by a script which is automatically
started after the U-Boot is up and running. To boot an OS with a an
USB keyboard another script is necessary, which first disables the
USB and then executes the boot command. If the boot command fails,
the script can reenable the USB kbd.

Common USB Commands:
- usb start:
- usb reset:	    (re)starts the USB. All USB devices will be
		    initialized and a device tree is build for them.
- usb tree:	    shows all USB devices in a tree like display
- usb info [dev]:   shows all USB infos of the device dev, or of all
		    the devices
- usb stop [f]:	    stops the USB. If f==1 the USB will also stop if
		    an USB keyboard is assigned as stdin. The stdin
		    is then switched to serial input.
Storage USB Commands:
- usb scan:	    scans the USB for storage devices.The USB must be
		    running for this command (usb start)
- usb device [dev]: show or set current USB staorage device
- usb part [dev]:   print partition table of one or all USB storage
		    devices
- usb read addr blk# cnt:
		    read `cnt' blocks starting at block `blk#'to
		    memory address `addr'
- usbboot addr dev:part:
		    boot from USB device

Config Switches:
----------------
CONFIG_CMD_USB	    enables basic USB support and the usb command
CONFIG_USB_UHCI	    defines the lowlevel part.A lowlevel part must be defined
		    if using CONFIG_CMD_USB
CONFIG_USB_KEYBOARD enables the USB Keyboard
CONFIG_USB_STORAGE  enables the USB storage devices
CONFIG_USB_HOST_ETHER	enables USB ethernet dongle support