[U-Boot] [PATCH v3 3/4] Add documentation for USB Host Networking
Simon Glass
sjg at chromium.org
Wed Apr 13 20:55:40 CEST 2011
This describes what it is for, devices supported, how to enable for your
board in U-Boot, setting up the server, and notes about MAC addresses.
Signed-off-by: Simon Glass <sjg at chromium.org>
---
doc/README.usb | 163 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 162 insertions(+), 1 deletions(-)
diff --git a/doc/README.usb b/doc/README.usb
index 9aa4f62..8693a05 100644
--- a/doc/README.usb
+++ b/doc/README.usb
@@ -79,4 +79,165 @@ 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
+CONFIG_USB_HOST_ETHER enables USB ethernet adapter support
+
+
+USB Host Networking
+===================
+
+If you have a supported USB Ethernet adapter you can use it in U-Boot
+to obtain an IP address and load a kernel from a network server.
+
+USB Host Networking is different from making your board act as a USB
+client. In that case your board is pretending to be an Ethernet adapter
+and will appear as a network interface to an attached computer. The
+connection is via a USB cable with the computer acting as the host.
+
+With USB Host Networking, your board is the USB host. It controls the
+Ethernet adapter to which it is directly connected and the connection to
+the outside world is your adapter's Ethernet cable. Your board becomes a
+first class network device, able to connect and perform network
+operations independently of your computer.
+
+
+Device support
+--------------
+
+Currently supported devices are listed in the drivers according to
+their vendor and product IDs. You can check your device by connecting it
+to a Linux machine and typing 'lsusb'. The drivers are in
+drivers/usb/eth.
+
+For example this lsusb output line shows a device with Vendor ID 0x0x95
+and product ID 0x7720:
+
+Bus 002 Device 010: ID 0b95:7720 ASIX Electronics Corp. AX88772
+
+If you look at drivers/usb/eth/asix.c you will see this line within the
+supported device list, so we know this adapter is supported.
+
+ { 0x0b95, 0x7720 }, /* Trendnet TU2-ET100 V3.0R */
+
+If your adapter is not listed there is a still a chance that it will
+work. Try looking up the manufacturer of the chip inside your adapter.
+or take the adapter apart and look for chip markings. Then add a line
+for your vendor/product ID into the table of the appropriate driver,
+build U-Boot and see if it works. If not then there might be differences
+between the chip in your adapter and the driver. You could try to get a
+datasheet for your device and add support for it to U-Boot. This is not
+particularly difficult - you only need to provide support for four basic
+functions: init, halt, send and recv.
+
+
+Enabling USB Host Networking
+----------------------------
+
+The normal U-Boot commands are used with USB networking, but you must
+start USB first. For example:
+
+usb start
+setenv bootfile /tftpboot/uImage
+setenv autoload y
+bootp
+
+
+(The autoload option makes bootp automatically load the boot file.)
+
+To enable USB Host Ethernet in U-Boot, your platform must of course
+support USB with CONFIG_CMD_USB enabled and working. You will need to
+add some config settings to your board header file:
+
+#define CONFIG_USB_HOST_ETHER /* Enable USB Ethernet adapters */
+#define CONFIG_USB_ETHER_ASIX /* Asix, or whatever driver(s) you want */
+
+You will also want to enable the network commands:
+
+#define CONFIG_CMD_NET
+#define CONFIG_NET_MULTI
+#define CONFIG_CMD_PING
+#define CONFIG_CMD_DHCP
+
+and some bootp options, which tell your board to obtain its subnet,
+gateway IP, host name and boot path from the bootp/dhcp server:
+
+#define CONFIG_BOOTP_SUBNETMASK
+#define CONFIG_BOOTP_GATEWAY
+#define CONFIG_BOOTP_HOSTNAME
+#define CONFIG_BOOTP_BOOTPATH
+
+You should also set the default IP address of your board and the server
+as well as the default file to load when a 'bootp' command is issued.
+
+#define CONFIG_IPADDR 10.0.0.2
+#define CONFIG_SERVERIP 10.0.0.1
+#define CONFIG_BOOTFILE uImage
+
+
+The 'usb start' command should identify the adapter something like this:
+
+CrOS> usb start
+(Re)start USB...
+USB EHCI 1.00
+scanning bus for devices... 3 USB Device(s) found
+ scanning bus for storage devices... 0 Storage Device(s) found
+ scanning bus for ethernet devices... 1 Ethernet Device(s) found
+CrOS> print ethact
+ethact=asx0
+
+You can see that it found an ethernet device and we can print out the
+device name (asx0 in this case).
+
+Then 'bootp' should use it to obtain an IP address from DHCP, perhaps
+something like this:
+
+CrOS> bootp
+Waiting for Ethernet connection... done.
+BOOTP broadcast 1
+BOOTP broadcast 2
+DHCP client bound to address 172.22.73.81
+Using asx0 device
+TFTP from server 172.22.72.144; our IP address is 172.22.73.81
+Filename '/tftpboot/uImage-sjg-seaboard-261347'.
+Load address: 0x40c000
+Loading: #################################################################
+ #################################################################
+ #################################################################
+ ################################################
+done
+Bytes transferred = 3557464 (364858 hex)
+CrOS>
+
+
+MAC Addresses
+-------------
+
+Most Ethernet dongles have a built-in MAC address which is unique in the
+world. This is important so that devices on the network can be
+distinguised from each other. MAC address conflicts are evil and
+generally result in strange and eratic behaviour.
+
+Some boards have USB Ethernet chips on-board, and these sometimes do not
+have an assigned MAC address. In this case it is up to you to assign
+one which is unique. You should obtain a valid MAC address from a range
+assigned to you before you ship the product.
+
+Built-in Ethernet adapters support setting the MAC address by means of
+an ethaddr environment variable for each interface (ethaddr, eth1addr,
+eth2addr). There is similar support on the USB network side, using the
+names usbethaddr, usbeth1addr, etc. They are kept separate since we
+don't want a USB device taking the MAC address of a built-in device or
+vice versa.
+
+So if your USB Ethernet chip doesn't have a MAC address available then
+you must set usbethaddr to a suitable MAC address. At the time of
+writing this functionality is only supported by the SMSC driver.
+
+
+Server Setup
+------------
+
+For setting up the server side (dhcpd, tftpd, nfsd) you might find this
+Chromium OS page useful:
+
+http://www.chromium.org/network-based-development
+
--
1.7.3.1
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