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b5f3850727
Fix spelling issues in README.usb. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
231 lines
8.4 KiB
Plaintext
231 lines
8.4 KiB
Plaintext
SPDX-License-Identifier: GPL-2.0+
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/*
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* (C) Copyright 2001
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* Denis Peter, MPL AG Switzerland
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*/
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USB Support
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===========
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The USB support is implemented on the base of the UHCI Host
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controller.
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Currently supported are USB Hubs, USB Keyboards, USB Floppys, USB
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flash sticks and USB network adaptors.
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Tested with a TEAC Floppy TEAC FD-05PUB and Chicony KU-8933 Keyboard.
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How it works:
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-------------
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The USB (at least the USB UHCI) needs a frame list (4k), transfer
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descriptor and queue headers which are all located in the main memory.
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The UHCI allocates every millisecond the PCI bus and reads the current
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frame pointer. This may cause to crash the OS during boot. So the USB
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_MUST_ be stopped during OS boot. This is the reason, why the USB is
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NOT automatically started during start-up. If someone needs the USB
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he has to start it and should therefore be aware that he had to stop
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it before booting the OS.
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For USB keyboards this can be done by a script which is automatically
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started after the U-Boot is up and running. To boot an OS with a
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USB keyboard another script is necessary, which first disables the
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USB and then executes the boot command. If the boot command fails,
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the script can re-enable the USB keyboard.
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Common USB Commands:
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- usb start:
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- usb reset: (re)starts the USB. All USB devices will be
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initialized and a device tree is build for them.
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- usb tree: shows all USB devices in a tree like display
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- usb info [dev]: shows all USB infos of the device dev, or of all
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the devices
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- usb stop [f]: stops the USB. If f==1 the USB will also stop if
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a USB keyboard is assigned as stdin. The stdin
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is then switched to serial input.
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Storage USB Commands:
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- usb scan: scans the USB for storage devices. The USB must be
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running for this command (usb start)
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- usb device [dev]: show or set current USB storage device
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- usb part [dev]: print partition table of one or all USB storage
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devices
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- usb read addr blk# cnt:
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read `cnt' blocks starting at block `blk#'to
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memory address `addr'
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- usbboot addr dev:part:
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boot from USB device
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Config Switches:
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----------------
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CONFIG_CMD_USB enables basic USB support and the usb command
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CONFIG_USB_UHCI defines the lowlevel part. A lowlevel part must be defined
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if using CONFIG_CMD_USB
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CONFIG_USB_KEYBOARD enables the USB Keyboard
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CONFIG_USB_STORAGE enables the USB storage devices
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CONFIG_USB_HOST_ETHER enables USB ethernet adapter support
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USB Host Networking
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===================
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If you have a supported USB Ethernet adapter you can use it in U-Boot
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to obtain an IP address and load a kernel from a network server.
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Note: USB Host Networking is not the same as making your board act as a USB
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client. In that case your board is pretending to be an Ethernet adapter
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and will appear as a network interface to an attached computer. In that
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case the connection is via a USB cable with the computer acting as the host.
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With USB Host Networking, your board is the USB host. It controls the
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Ethernet adapter to which it is directly connected and the connection to
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the outside world is your adapter's Ethernet cable. Your board becomes an
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independent network device, able to connect and perform network operations
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independently of your computer.
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Device support
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--------------
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Currently supported devices are listed in the drivers according to
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their vendor and product IDs. You can check your device by connecting it
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to a Linux machine and typing 'lsusb'. The drivers are in
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drivers/usb/eth.
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For example this lsusb output line shows a device with Vendor ID 0x0x95
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and product ID 0x7720:
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Bus 002 Device 010: ID 0b95:7720 ASIX Electronics Corp. AX88772
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If you look at drivers/usb/eth/asix.c you will see this line within the
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supported device list, so we know this adapter is supported.
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{ 0x0b95, 0x7720 }, /* Trendnet TU2-ET100 V3.0R */
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If your adapter is not listed there is a still a chance that it will
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work. Try looking up the manufacturer of the chip inside your adapter.
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or take the adapter apart and look for chip markings. Then add a line
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for your vendor/product ID into the table of the appropriate driver,
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build U-Boot and see if it works. If not then there might be differences
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between the chip in your adapter and the driver. You could try to get a
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datasheet for your device and add support for it to U-Boot. This is not
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particularly difficult - you only need to provide support for four basic
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functions: init, halt, send and recv.
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Enabling USB Host Networking
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----------------------------
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The normal U-Boot commands are used with USB networking, but you must
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start USB first. For example:
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usb start
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setenv bootfile /tftpboot/uImage
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bootp
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To enable USB Host Ethernet in U-Boot, your platform must of course
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support USB with CONFIG_CMD_USB enabled and working. You will need to
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add some settings to your board configuration:
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CONFIG_CMD_USB=y /* the 'usb' interactive command */
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CONFIG_USB_HOST_ETHER=y /* Enable USB Ethernet adapters */
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and one or more of the following for individual adapter hardware:
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CONFIG_USB_ETHER_ASIX=y
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CONFIG_USB_ETHER_ASIX88179=y
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CONFIG_USB_ETHER_LAN75XX=y
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CONFIG_USB_ETHER_LAN78XX=y
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CONFIG_USB_ETHER_MCS7830=y
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CONFIG_USB_ETHER_RTL8152=y
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CONFIG_USB_ETHER_SMSC95XX=y
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As with built-in networking, you will also want to enable some network
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commands, for example:
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CONFIG_CMD_NET=y
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CONFIG_CMD_PING=y
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CONFIG_CMD_DHCP=y
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and some bootp options, which tell your board to obtain its subnet,
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gateway IP, host name and boot path from the bootp/dhcp server. These
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settings should start you off:
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#define CONFIG_BOOTP_SUBNETMASK
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#define CONFIG_BOOTP_GATEWAY
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#define CONFIG_BOOTP_HOSTNAME
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#define CONFIG_BOOTP_BOOTPATH
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You can also set the default IP address of your board and the server
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as well as the default file to load when a 'bootp' command is issued.
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However note that encoding these individual network settings into a
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common executable is discouraged, as it leads to potential conflicts,
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and all the parameters can either get stored in the board's external
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environment, or get obtained from the bootp server if not set.
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#define CONFIG_IPADDR 10.0.0.2 (replace with your value)
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#define CONFIG_SERVERIP 10.0.0.1 (replace with your value)
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#define CONFIG_BOOTFILE "uImage"
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The 'usb start' command should identify the adapter something like this:
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CrOS> usb start
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(Re)start USB...
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USB EHCI 1.00
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scanning bus for devices... 3 USB Device(s) found
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scanning bus for storage devices... 0 Storage Device(s) found
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scanning bus for ethernet devices... 1 Ethernet Device(s) found
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CrOS> print ethact
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ethact=asx0
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You can see that it found an ethernet device and we can print out the
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device name (asx0 in this case).
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Then 'bootp' or 'dhcp' should use it to obtain an IP address from DHCP,
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perhaps something like this:
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CrOS> bootp
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Waiting for Ethernet connection... done.
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BOOTP broadcast 1
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BOOTP broadcast 2
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DHCP client bound to address 172.22.73.81
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Using asx0 device
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TFTP from server 172.22.72.144; our IP address is 172.22.73.81
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Filename '/tftpboot/uImage-sjg-seaboard-261347'.
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Load address: 0x40c000
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Loading: #################################################################
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#################################################################
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#################################################################
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################################################
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done
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Bytes transferred = 3557464 (364858 hex)
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CrOS>
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Another way of doing this is to issue a tftp command, which will cause the
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bootp to happen automatically.
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MAC Addresses
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-------------
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Most Ethernet dongles have a built-in MAC address which is unique in the
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world. This is important so that devices on the network can be
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distinguished from each other. MAC address conflicts are evil and
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generally result in strange and erratic behaviour.
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Some boards have USB Ethernet chips on-board, and these sometimes do not
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have an assigned MAC address. In this case it is up to you to assign
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one which is unique. You should obtain a valid MAC address from a range
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assigned to you before you ship the product.
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Built-in Ethernet adapters support setting the MAC address by means of
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an ethaddr environment variable for each interface (ethaddr, eth1addr,
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eth2addr). There is similar support on the USB network side, using the
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names usbethaddr, usbeth1addr, etc. They are kept separate since we
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don't want a USB device taking the MAC address of a built-in device or
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vice versa.
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So if your USB Ethernet chip doesn't have a MAC address available then
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you must set usbethaddr to a suitable MAC address. At the time of
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writing this functionality is only supported by the SMSC driver.
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