xref: /openbmc/u-boot/doc/README.usb (revision 26749582)
1/*
2 * (C) Copyright 2001
3 * Denis Peter, MPL AG Switzerland
4 *
5 * See file CREDITS for list of people who contributed to this
6 * project.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21 * MA 02111-1307 USA
22 *
23 */
24
25USB Support for PIP405 and MIP405 (UHCI)
26========================================
27
28The USB support is implemented on the base of the UHCI Host
29controller.
30
31Currently supported are USB Hubs, USB Keyboards, USB Floppys, USB
32flash sticks and USB network adaptors.
33Tested with a TEAC Floppy TEAC FD-05PUB and Chicony KU-8933 Keyboard.
34
35How it works:
36-------------
37
38The USB (at least the USB UHCI) needs a frame list (4k), transfer
39descripor and queue headers which are all located in the main memory.
40The UHCI allocates every milisecond the PCI bus and reads the current
41frame pointer. This may cause to crash the OS during boot. So the USB
42_MUST_ be stopped during OS boot. This is the reason, why the USB is
43NOT automatically started during start-up. If someone needs the USB
44he has to start it and should therefore be aware that he had to stop
45it before booting the OS.
46
47For USB keyboards this can be done by a script which is automatically
48started after the U-Boot is up and running. To boot an OS with a an
49USB keyboard another script is necessary, which first disables the
50USB and then executes the boot command. If the boot command fails,
51the script can reenable the USB kbd.
52
53Common USB Commands:
54- usb start:
55- usb reset:	    (re)starts the USB. All USB devices will be
56		    initialized and a device tree is build for them.
57- usb tree:	    shows all USB devices in a tree like display
58- usb info [dev]:   shows all USB infos of the device dev, or of all
59		    the devices
60- usb stop [f]:	    stops the USB. If f==1 the USB will also stop if
61		    an USB keyboard is assigned as stdin. The stdin
62		    is then switched to serial input.
63Storage USB Commands:
64- usb scan:	    scans the USB for storage devices.The USB must be
65		    running for this command (usb start)
66- usb device [dev]: show or set current USB staorage device
67- usb part [dev]:   print partition table of one or all USB storage
68		    devices
69- usb read addr blk# cnt:
70		    read `cnt' blocks starting at block `blk#'to
71		    memory address `addr'
72- usbboot addr dev:part:
73		    boot from USB device
74
75Config Switches:
76----------------
77CONFIG_CMD_USB	    enables basic USB support and the usb command
78CONFIG_USB_UHCI	    defines the lowlevel part.A lowlevel part must be defined
79		    if using CONFIG_CMD_USB
80CONFIG_USB_KEYBOARD enables the USB Keyboard
81CONFIG_USB_STORAGE  enables the USB storage devices
82CONFIG_USB_HOST_ETHER	enables USB ethernet dongle support
83