doc/README.usb

   1 /*
   2  * (C) Copyright 2001
   3  * Denis Peter, MPL AG Switzerland
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 USB Support
   9 ===========
  10
  11 The USB support is implemented on the base of the UHCI Host
  12 controller.
  13
  14 Currently supported are USB Hubs, USB Keyboards, USB Floppys, USB
  15 flash sticks and USB network adaptors.
  16 Tested with a TEAC Floppy TEAC FD-05PUB and Chicony KU-8933 Keyboard.
  17
  18 How it works:
  19 -------------
  20
  21 The USB (at least the USB UHCI) needs a frame list (4k), transfer
  22 descripor and queue headers which are all located in the main memory.
  23 The UHCI allocates every milisecond the PCI bus and reads the current
  24 frame pointer. This may cause to crash the OS during boot. So the USB
  25 _MUST_ be stopped during OS boot. This is the reason, why the USB is
  26 NOT automatically started during start-up. If someone needs the USB
  27 he has to start it and should therefore be aware that he had to stop
  28 it before booting the OS.
  29
  30 For USB keyboards this can be done by a script which is automatically
  31 started after the U-Boot is up and running. To boot an OS with a an
  32 USB keyboard another script is necessary, which first disables the
  33 USB and then executes the boot command. If the boot command fails,
  34 the script can reenable the USB kbd.
  35
  36 Common USB Commands:
  37 - usb start:
  38 - usb reset:        (re)starts the USB. All USB devices will be
  39                     initialized and a device tree is build for them.
  40 - usb tree:         shows all USB devices in a tree like display
  41 - usb info [dev]:   shows all USB infos of the device dev, or of all
  42                     the devices
  43 - usb stop [f]:     stops the USB. If f==1 the USB will also stop if
  44                     an USB keyboard is assigned as stdin. The stdin
  45                     is then switched to serial input.
  46 Storage USB Commands:
  47 - usb scan:         scans the USB for storage devices.The USB must be
  48                     running for this command (usb start)
  49 - usb device [dev]: show or set current USB storage device
  50 - usb part [dev]:   print partition table of one or all USB storage
  51                     devices
  52 - usb read addr blk# cnt:
  53                     read `cnt' blocks starting at block `blk#'to
  54                     memory address `addr'
  55 - usbboot addr dev:part:
  56                     boot from USB device
  57
  58 Config Switches:
  59 ----------------
  60 CONFIG_CMD_USB      enables basic USB support and the usb command
  61 CONFIG_USB_UHCI     defines the lowlevel part.A lowlevel part must be defined
  62                     if using CONFIG_CMD_USB
  63 CONFIG_USB_KEYBOARD enables the USB Keyboard
  64 CONFIG_USB_STORAGE  enables the USB storage devices
  65 CONFIG_USB_HOST_ETHER   enables USB ethernet adapter support
  66
  67
  68 USB Host Networking
  69 ===================
  70
  71 If you have a supported USB Ethernet adapter you can use it in U-Boot
  72 to obtain an IP address and load a kernel from a network server.
  73
  74 Note: USB Host Networking is not the same as making your board act as a USB
  75 client. In that case your board is pretending to be an Ethernet adapter
  76 and will appear as a network interface to an attached computer. In that
  77 case the connection is via a USB cable with the computer acting as the host.
  78
  79 With USB Host Networking, your board is the USB host. It controls the
  80 Ethernet adapter to which it is directly connected and the connection to
  81 the outside world is your adapter's Ethernet cable. Your board becomes an
  82 independent network device, able to connect and perform network operations
  83 independently of your computer.
  84
  85
  86 Device support
  87 --------------
  88
  89 Currently supported devices are listed in the drivers according to
  90 their vendor and product IDs. You can check your device by connecting it
  91 to a Linux machine and typing 'lsusb'. The drivers are in
  92 drivers/usb/eth.
  93
  94 For example this lsusb output line shows a device with Vendor ID 0x0x95
  95 and product ID 0x7720:
  96
  97 Bus 002 Device 010: ID 0b95:7720 ASIX Electronics Corp. AX88772
  98
  99 If you look at drivers/usb/eth/asix.c you will see this line within the
 100 supported device list, so we know this adapter is supported.
 101
 102         { 0x0b95, 0x7720 },     /* Trendnet TU2-ET100 V3.0R */
 103
 104 If your adapter is not listed there is a still a chance that it will
 105 work. Try looking up the manufacturer of the chip inside your adapter.
 106 or take the adapter apart and look for chip markings. Then add a line
 107 for your vendor/product ID into the table of the appropriate driver,
 108 build U-Boot and see if it works. If not then there might be differences
 109 between the chip in your adapter and the driver. You could try to get a
 110 datasheet for your device and add support for it to U-Boot. This is not
 111 particularly difficult - you only need to provide support for four basic
 112 functions: init, halt, send and recv.
 113
 114
 115 Enabling USB Host Networking
 116 ----------------------------
 117
 118 The normal U-Boot commands are used with USB networking, but you must
 119 start USB first. For example:
 120
 121 usb start
 122 setenv bootfile /tftpboot/uImage
 123 bootp
 124
 125
 126 To enable USB Host Ethernet in U-Boot, your platform must of course
 127 support USB with CONFIG_CMD_USB enabled and working. You will need to
 128 add some config settings to your board config:
 129
 130 CONFIG_CMD_USB=y                /* the 'usb' interactive command */
 131 CONFIG_USB_HOST_ETHER=y         /* Enable USB Ethernet adapters */
 132
 133 and one or more of the following for individual adapter hardware:
 134
 135 CONFIG_USB_ETHER_ASIX=y
 136 CONFIG_USB_ETHER_ASIX88179=y
 137 CONFIG_USB_ETHER_LAN75XX=y
 138 CONFIG_USB_ETHER_LAN78XX=y
 139 CONFIG_USB_ETHER_MCS7830=y
 140 CONFIG_USB_ETHER_RTL8152=y
 141 CONFIG_USB_ETHER_SMSC95XX=y
 142
 143 As with built-in networking, you will also want to enable some network
 144 commands, for example:
 145
 146 CONFIG_CMD_NET=y
 147 CONFIG_CMD_PING=y
 148 CONFIG_CMD_DHCP=y
 149
 150 and some bootp options, which tell your board to obtain its subnet,
 151 gateway IP, host name and boot path from the bootp/dhcp server. These
 152 settings should start you off:
 153
 154 #define CONFIG_BOOTP_SUBNETMASK
 155 #define CONFIG_BOOTP_GATEWAY
 156 #define CONFIG_BOOTP_HOSTNAME
 157 #define CONFIG_BOOTP_BOOTPATH
 158
 159 You can also set the default IP address of your board and the server
 160 as well as the default file to load when a 'bootp' command is issued.
 161 However note that encoding these individual network settings into a
 162 common exectuable is discouraged, as it leads to potential conflicts,
 163 and all the parameters can either get stored in the board's external
 164 environment, or get obtained from the bootp server if not set.
 165
 166 #define CONFIG_IPADDR           10.0.0.2  (replace with your value)
 167 #define CONFIG_SERVERIP         10.0.0.1  (replace with your value)
 168 #define CONFIG_BOOTFILE         "uImage"
 169
 170
 171 The 'usb start' command should identify the adapter something like this:
 172
 173 CrOS> usb start
 174 (Re)start USB...
 175 USB EHCI 1.00
 176 scanning bus for devices... 3 USB Device(s) found
 177        scanning bus for storage devices... 0 Storage Device(s) found
 178        scanning bus for ethernet devices... 1 Ethernet Device(s) found
 179 CrOS> print ethact
 180 ethact=asx0
 181
 182 You can see that it found an ethernet device and we can print out the
 183 device name (asx0 in this case).
 184
 185 Then 'bootp' or 'dhcp' should use it to obtain an IP address from DHCP,
 186 perhaps something like this:
 187
 188 CrOS> bootp
 189 Waiting for Ethernet connection... done.
 190 BOOTP broadcast 1
 191 BOOTP broadcast 2
 192 DHCP client bound to address 172.22.73.81
 193 Using asx0 device
 194 TFTP from server 172.22.72.144; our IP address is 172.22.73.81
 195 Filename '/tftpboot/uImage-sjg-seaboard-261347'.
 196 Load address: 0x40c000
 197 Loading: #################################################################
 198          #################################################################
 199          #################################################################
 200          ################################################
 201 done
 202 Bytes transferred = 3557464 (364858 hex)
 203 CrOS>
 204
 205
 206 Another way of doing this is to issue a tftp command, which will cause the
 207 bootp to happen automatically.
 208
 209
 210 MAC Addresses
 211 -------------
 212
 213 Most Ethernet dongles have a built-in MAC address which is unique in the
 214 world. This is important so that devices on the network can be
 215 distinguised from each other. MAC address conflicts are evil and
 216 generally result in strange and eratic behaviour.
 217
 218 Some boards have USB Ethernet chips on-board, and these sometimes do not
 219 have an assigned MAC address. In this case it is up to you to assign
 220 one which is unique. You should obtain a valid MAC address from a range
 221 assigned to you before you ship the product.
 222
 223 Built-in Ethernet adapters support setting the MAC address by means of
 224 an ethaddr environment variable for each interface (ethaddr, eth1addr,
 225 eth2addr). There is similar support on the USB network side, using the
 226 names usbethaddr, usbeth1addr, etc. They are kept separate since we
 227 don't want a USB device taking the MAC address of a built-in device or
 228 vice versa.
 229
 230 So if your USB Ethernet chip doesn't have a MAC address available then
 231 you must set usbethaddr to a suitable MAC address. At the time of
 232 writing this functionality is only supported by the SMSC driver.