ATUWI - The FreeBSD USB WLAN driver project


**** Current driver features

- Support for Intersil, RFMD, RFMD2958 radio parts.
- Supports boards based on both the AT76c503 and the AT76c505 chipset.
- Support for the SMC 2662W v.4 adapter
- Support for Ad-hoc networks.
- Support for Infrastructure mode (currently in infrastructure mode only 'open
  system' authentication is implemented).
- Setting the channel / SSID / WEP mode / WEP key / mac-addr via ifconfig.
- Automatic scanning and associating with a wireless network.
- bpf support for both DLT_EN10MB and DLT_IEEE802_11.
- Also compiles on FreeBSD 5.2 and later now.



**** Known BUGS and limitations

- 'shared key' authentication is not yet implemented.
- There is no timeout when we're associated and connected to a network. Once
  the driver is associated with an AP it assumes the connection will stay
  forever.
- Nothing is done with the reg-domain of the device. Right now setting
  an unsupported channel will not return any error, but the device will
  simply refuse to work.
- Only 'auto rate fallback' is supported at this moment. There is no way to
  force the driver to use a specified transmit-rate.
- The firmware doesn't have a real promiscuous mode. We only receeive things
  addressed to us and to the broadcast address.



**** Installing the driver

To use this driver you need FreeBSD 5.1-RELEASE or later with the kernel
sources installed.

First, unpack the driver into your source tree. (You may want to create
backups of your source tree before you begin.)

# cd /usr/src
# tar -xvzf /the/path/to/atuwi-0.4.tar.gz

This should extract the following files :
sys/dev/usb/if_atuwi.c
sys/dev/usb/if_atuwireg.h
sys/dev/usb/atuwi_rfmd_fw.h
sys/dev/usb/atuwi_rfmd2958_fw.h
sys/dev/usb/atuwi_rfmd2958-smc_fw.h
sys/dev/usb/atuwi_intersil_fw.h
sys/dev/usb-reset-2004-01-08.diff
sys/modules/atuwi/Makefile
sys/modules/atuwi/CHANGELOG
sys/modules/atuwi/atuwi-README.txt
sys/conf/files-atuwi-2004-01-11.diff

The atuwi-driver uses a system called 'DFU' to upload firmware into the USB
adapter. After the firmware has been uploaded, the adapter has to be
resetted. The current USB stack doesn't have the ability to do this in a
nice way, so I have added this functionality and provided a patch.
Patching your USB code and recompiling it can be done as follows:
# cd /usr/src/sys/dev
# patch <usb-reset-2004-01-08.diff

Now update the usbdevs list with the ID's of the WLAN adapters and rebuild it:
(this can also be done using cvs, but for ease of use we'll just get the
usbdevs list from the cvsweb interface using fetch)
# cd /usr/src/sys/dev/usb
# fetch http://www.freebsd.org/cgi/cvsweb.cgi/~checkout~/src/sys/dev/usb/usbdevs
# make -f Makefile.usbdevs

Note that for the changes to take effect you'll have to recompile your
kernel and reboot now. Otherwise the driver will work, but you will have to
use a trick to get the firmware to work. (Which is explained later on)

After that it's time to compile the driver itself :
# cd /usr/src/sys/modules/atuwi
# make

If you've made it up to here you should now be the happy owner of a file
called 'if_atuwi.ko'. Let's try to load it and see if it works...
# kldload /usr/src/sys/modules/atuwi/if_atuwi.ko

Now plug in the WLAN adapter and watch the debug output. If all goes well
the debug messages will stop with something like :
'atuwi0: Atmel Wireless adapter, rev 1.10/1.00, addr 3 attached successfully'

Congratulations, you can now begin configuring the interface (and skip the
next chapter). If the debug messages stop with something like
'device_probe_and_attach: atuwi0 attach returned 35', read the next chapter.
If you don't see any debug messages that start with 'atuwi0', you must have
a WLAN adapter that's either not supported, or not yet listed in the driver.
Please email me ( Danovitsch @ Vitsch . net ) the output of 'usbdevs -v' so
I can add the USB ID's to the driver.



**** How to reset the adapter without the reset code in the kernel?

If for some reasone you are using a kernel without my reset modifications,
you will have to use a little trick to reset the adapter. If you remove a
USB plug from a hub, you first disconnect the two data pins and then the two
pins supplying the power. (This is because the data pins are shorter in
length.) So if you gently unplug the USB connector only half way out of the
hub (about 2 milimeters) the data pins are disconnected from the hub, but
the device is still powered. This means the hub will detect the device is
gone, but the firmware will stay in the RAM of the device. When you plug the
device back in now, the hub will detect the device again.
Doing this is fairly easy, but it won't always work on the first attempt.
Just try a couple of times.



**** Examples of joining a network in Ad-Hoc and Infrastructure mode

The following are a couple of self-explenatory examples that show how the
interface can be configured :

# ifconfig atuwi0 192.168.1.10 ssid "SomeName"
This command let the driver scan all channels and try to join an Access
Point with ssid 'SomeName'.

# ifconfig atuwi0 192.168.1.10 ssid "Some Other Name" mediaopt adhoc channel 3
After this command the driver will scan all channels for an adhoc network
with ssid 'Some Other Name'. It will connect to the first match it finds,
regardless of the given channel.
If no network is found, the driver will start it's own network on channel 3.

Switching back from Ad-Hoc mode to Infrastructure mode can be done with this
command :
# ifconfig atuwi0 -mediaopt adhoc

And switching from Infrastructure to Ad-Hoc can be done like this:
# ifconfig atuwi0 mediaopt adhoc



**** Configuring the interface to use WEP encryption

The following command will set a 64-bit WEP key :
# ifconfig atuwi0 wepmode on weptxkey 1 wepkey 1:0x1122334455

And setting a 128-bit WEP key :
# ifconfig atuwi0 wepmode on weptxkey 1 wepkey 1:0x11223344556677889900112233

Turning WEP off again :
# ifconfig atuwi0 wepmode off

Possible wepmode's are :
off	no encryption is done when transmitting.
mixed	transmitted packets are encrypted, but both encrypted and
	non-encrypted packets are received.
on	transmitted packets are encrypted. only WEP encrypted packets are
	received.

WEP encrypted packets will ONLY be received if the transmitter and the
receiver are using the exact same WEP key (wether we're in mixed mode or
not).

When setting WEP keys, make sure the length is exactly 10 hex-digits for
64-bit keys or 23 hex-digits for 128-bits.



**** Setting up your system to automagically configure the interface

If you are going to plug/unplug the adapter, you probably want the thing to
be automatically configured when it's plugged in. USBD will do this for us
after some minor modifications.

# edit /etc/usbd.conf
Somewhere in the file add the next couple of lines :

device "USB WLAN"
        devname "atuwi[0-9]+" 
        attach  "/etc/pccard_ether ${DEVNAME} start"
        detach  "/etc/pccard_ether ${DEVNAME} stop"

Save the file and restart usbd :
# killall -TERM usbd
# usbd

Now add your settings to /etc/rc.conf . The syntax should look like this :
ifconfig_atuwi0="192.168.3.20 ssid TheNetworkName wepmode on weptxkey 1 etc.."

To let the system know we want to automatically load the settings add :
removable_interfaces="atuwi0"

And to make 'usbd' start during boot you should have :
usbd_enable="YES"

After plugging the device into the usb hub it should now be automatically
detected and configured.



**** Compiling the driver into the kernel

Although it's possible to load the driver at boot time it might be easier to
compile the driver into the kernel sometimes. To do this we have to add the
driver to the list of options that can be choosen in a kernel-config :
# cd /usr/src/sys/conf
# patch files files-atuwi-2004-01-11.diff

Now edit your kernel config file and simply add a line with 'device atuwi' to
it. Re-config, compile, install, reboot and the adapter should initialise at
boot time :)



**** Using the driver during 'sysinstall' from a floppy

What if you're with your laptop in the middle of nowhere, far from your
cat-5 hub, but just in range of a wireless network and you suddenly feel the
urge to install FreeBSD?
Well... I found myself in that situation yesterday and I found out that
using the driver from sysinstall is very easy and completely painless :)
First, make your kernel & mfsroot floppies. Then take a third floppy and put
the driver on it :

Format the floppy
# fdformat /dev/fd0
# disklabel -w -r /dev/fd0 fd1440
# newfs /dev/fd0

Mount it, copy the driver and unmount it again.
# mount -t ufs /dev/fd0 /mnt
# cp /usr/src/sys/modules/atuwi/if_atuwi.ko /mnt
# umount /mnt

Now boot your system with the kernel & mfsroot floppies. When sysinstall
appears simply insert the driver floppy and follow the menu to load it.
During install things like ssid and WEP-settings can be filled in in the box
'extra options to ifconfig'.


For those that are having a little chicken-and-egg problem with the 'compile
the driver, put it on a floppy, and then install FreeBSD' order and for the
impatient, the floppy image can also be downloaded from the internet from :

For FreeBSD 5.1-RELEASE :
http://vitsch.net/bsd/atuwi/floppies/atuwi-driver-5.1-release.flp.tar.gz
For FreeBSD 5.2.1-RELEASE :
http://vitsch.net/bsd/atuwi/floppies/atuwi-driver-5.2.1-release.flp.tar.gz

After downloading, extract the image and burn it onto a floppy. The driver
on the floppy image supports both RFMD and Intersil devices.



**** Some final tips

By default the driver tends to be a bit too verbose. The debug flags can be
altered on-the-fly with sysctl variable 'hw.atuwi.debug' .

This will silence the driver:
sysctl -w hw.atuwi.debug=0x00

For an explanation of possible debug flags, settings and optimizations of
the driver please have a look at /usr/src/sys/dev/usb/if_atuwireg.h