$Id$


WARNING: THIS IS A BETA DISTRIBUTION.  THIS SOFTWARE HAS KNOWN PROBLEMS AND
WARNING: LIMITATIONS THAT WILL BE CORRECTED BEFORE A PRODUCTION RELEASE.
WARNING: DON'T BLAME US IF THE SOFTWARE EATS YOUR SYSTEM, DESTROYS YOUR DISK
WARNING: OR MAKES YOUR CORN-FLAKES SOGGY.
WARNING: USE AT YOUR OWN RISK!


MADWIFI: Multimode Atheros Driver for WiFi on Linux (BSD branch)
================================================================

* Copyright (c) 2002-2004 Sam Leffler.  All rights reserved.

Read the file COPYRIGHT for the complete copyright.

NOTE: This file describes the contents of the "BSD branch" of the
      MADWIFI project. This branch is used to import recent
      changes from the FreeBSD Atheros driver.

This software contains a Linux kernel driver for Atheros-based
Wireless LAN devices.  The driver supports station, AP, adhoc, and
monitor modes of operation.  The Atheros driver depends on a
device-independent implementation of the 802.11 protocols that
originated in the BSD community (NetBSD in particular).  You will
find a small amount of BSD-ish glue code that exists mainly to
minimize diffs with the BSD variants. However as much as possible
this is "native Linux code" that tries to conform to Linux style
and operation.

The driver functions as a normal network device and uses the Wireless
Extensions API.  As such normal Linux tools can and should be used
with it.  Where the wireless extensions are lacking private ioctls
have been added.

There is only one driver included here; it supports both miniPCI
and Cardbus devices.  The driver can be built as a module or linked
directly into the kernel.  Note however that the net80211 layer is
device-independent; there is no reason it cannot be used with any
802.11 device (in fact on BSD systems this is the case).

This software is broken into multiple modules.  The Atheros-specific
device support is found in the ath_pci module; it should be loaded
when an Atheros wireless device is recognized.  The ath_pci module
requires an additional device specific module, ath_hal, which is
described more below.  In addition the driver requires the wlan
module which contains the 802.11 state machine, protocol support,
and other device-independent support needed by any 802.11 device.
This code is derived from work that first appeared in NetBSD and
then FreeBSD.  The wlan module may also force the loading of
additional modules for crypto support (wlan_wep, wlan_tkip, wlan_ccmp,
etc.), for MAC-based ACL support (wlan_acl), and for 802.1x
authenticator support (wlan_auth, wlan_radius)).  The latter modules
are only used when operating as an AP.  The crypto modules are
loaded when keys of that type are created.

The ath_hal module contains the Atheros Hardware Access Layer (HAL).
This code manages much of the chip-specific operation of the driver.
The HAL is provided in a binary-only form in order to comply with FCC
regulations.  In particular, a radio transmitter can only be operated at
power levels and on frequency channels for which it is approved.  The FCC
requires that a software-defined radio cannot be configured by a user
to operate outside the approved power levels and frequency channels.
This makes it difficult to open-source code that enforces limits on
the power levels, frequency channels and other parameters of the radio
transmitter.  See

http://ftp.fcc.gov/Bureaus/Engineering_Technology/Orders/2001/fcc01264.pdf

for the specific FCC regulation.  Because the module is provided in a
binary-only form it is marked "Proprietary"; this means when you load
it you will see messages that your system is now "tainted".

If you wish to use this driver on a platform for which an ath_hal
module is not already provided please contact the author.  Note that
this is only necessary for new _architectures_; the HAL is not tied to
any specific version of Linux--in fact the identical HAL binary code
is used unchanged with other operating systems.


Driver status
-------------

At the moment there exist no stable releases for madwifi project.
We are working on it but for now only the sourceforge cvs and 
daily snapshots at http://madwifi.otaku42.de/ exist.

The following list is updated incrementally. Only if a feature
has proven to be stable it is marked "OK".

Super AG			???
Atheros XR			???
Virtual AP			???
802.11e (QoS)			???
802.11h (DFS, TPC)		???
WDS support			???
Power Safe mode			???
WPA 1/2 AP support (hostapd)	???
Managed mode (client)		???
Master mode (AP)		???
Ad-Hoc mode			???
Monitor/Promiscuous mode	???
Throughput 802.11b		??? (specs)
Throughput 802.11g		??? (specs)
Throughput 802.11a		??? (specs)
Kismet support			???
Linux Wireless API Support	???
Platform independence		???
Full Linux Wireless compat	???
SMP-safe			???
ACPI support			???


Atheros Hardware
================
There are currently 3 "programming generations" of Atheros 802.11
wireless devices (some of these have multiple hardware implementations
but otherwise appear identical to users):

5210	supports 11a only
5211	supports both 11a and 11b
5212	supports 11a, 11b, and 11g

These parts have been incorporated in a variety of retail products
including cardbus cards from DLink, Linksys, Netgear, Orinoco,
Proxim, and 3Com; and mini-pci cards from some of these same vendors.
In addition many laptop vendors use Atheros mini-pci cards for their
builtin wireless support.  For an up-to-date list of cards based
on Atheros parts visit:

http://customerproducts.atheros.com/customerproducts

In general, if a device is identified as ``11a only'' it is almost
certain to contain an Atheros 5210 part in it.  Most retail a+b
products use the 5211.  Many a+b+g combo products use the 5212
though other vendors have started to offer dual-band support.  When
in doubt check the PCI vendor id with a tool like lspci, the Atheros
vendor id is 0x168c; e.g.

   00:13.0 Ethernet controller: Unknown device 168c:0012 (rev 01)

but beware that come vendors use alternate vendor id's (e.g 3Com, IBM).
The file hal/ah_devid.h has a list of known PCI id's.


Using the driver
================
The driver should support any Atheros-based cardbus or pci device.
Management is done using the normal Linux tools such as ifconfig,
iwconfig, and iwpriv.

To use this software in ``station mode'' (i.e. as a client) just
bring the interface up and the driver will scan for all access
points in all supported frequency bands supported by the hardware.
Specifically for 5210-based devices scanning will happen in the
5Ghz (11a) range, for 5211-based devices scanning will happen over
both 2Ghz (11b) and 5GHz frequencies (11a).  For 5212-based devices
the driver will scan both 2Ghz and 5GHz ranges and also look for
11g devices in the 2Ghz range.  To restrict operation you can either
select a mode (e.g. 11b) using iwpriv or, more commonly, select the
AP based on SSID and/or channel.

NOTE: You must mark the interface ``up'' with, e.g. ifconfig ath0 up
      before scanning for access points with iwlist.

To use this software in ``hostap mode'' you need to configure it
with iwconfig and you will probably want to lock the operating mode
to one of 11a, 11b, or 11g if you have a multi-mode card (if you
do not lock the mode then the driver will select a mode for you;
usually 11a).  In addition you will need to configure the system to
bridge frames to a wired LAN or similar.

Wireless tools cribsheet:

iwlist ath0 scan		list AP's the driver has scanned
iwconfig ath0 essid "foo"	set the ssid to foo
iwpriv ath0 mode 1		lock operation to 11a only
iwpriv ath0 mode 2		lock operation to 11b only
iwpriv ath0 mode 3		lock operation to 11g only
iwpriv ath0 mode 0		autoselect from 11a/b/g (default)

There are some debugging mechanisms for the curious/masochistic:

sysctl -w dev.ath.debug=0xXXX	enable console msgs from the driver
sysctl -w net.wlan0.debug=0xYYY	enable console msgs from the wlan module

The values specified for 0XXX and 0xYYY are bit masks that enable
debugging in various parts of each module.  For the wlan module
these values are found in the file net80211/ieee80211_var.h (search
for MSG_).  For the ath driver look in ath/if_ath.c (search for
ATH_DEBUG).  Beware that enabling some debugging msgs can affect
the operation of the software by slowing it down too much.  The
programs tools/athdebug and tools/80211debug allow you to do the
above using symbol names; e.g.

athdebug +xmit
80211debug scan+assoc

In addition the programs tools/athstats and tools/80211stats can
be very useful in understanding what is going on.  In particular,
something like:

trouble% athstats 1

will give a running display of the most interesting statistics sampled
every 1 second.  Running athstats without any options will display a
summary of all non-zero statistics from the time the driver was loaded.

NOTE: By default the ath0 device is used; to override this use the 
      -i athX option.


Security/Crpto Support
======================
All Atheros devices implement fixed/shared key WEP in hardware.  Newer
Atheros hardware is capable of much more (e.g. AES, TKIP and Michael).
When hardware support is not available for a cipher the net80211 layer
will automatically do the work in software.

WPA/802.11i station operation (aka supplicant) is supported using Jouni
Malinen's wpa_supplicant program.  This can obtained from:

http://hostap.epitest.fi/wpa_supplicant/

wpa_supplicant also supports a wide range of 802.1x EAP methods, either
together with WPA/WPA2 or without; consult the wpa_supplicant documentation
for an up to date list.

NOTE: the in-kernel authenticator is being replaced; to use it you need
      to follow the directions in net80211/Makefile.

When operating as an AP you can use fixed/shared key ciphers, 802.1x,
and/or WPA authentication.  The authentication mode is specified using
iwpriv:

iwpriv ath0 authmode 1		# open authenticatoin
iwpriv ath0 authmode 2		# shared key authentication
iwpriv ath0 authmode 3		# 802.1x authentication

To use the 802.1x authenticator you must install and configure the hostapd
program from the same place you got wpa_supplicant.  Consult the hostapd
documentation for its' setup.


Known Problems
==============
[All these problems are to be fixed in future revisions.]

1. Performance in lossy environments is suboptimal.  The algorithm used to
   select the rate for transmitted packets is very simplistic.  There is no
   software retransmit; only hardware retransmit is used.  Contributors are
   encouraged to replace the existing rate control algorithm with a better
   one (hint: all the information needed is available in the driver).

Acknowledgements
================
This work could not have been done without the support of Atheros
and in particular the efforts of Greg Chesson.  Comments from David
Miller were helpful in cleaning up some of the roughest edges in
early versions of the driver.

Many people have contributed fixes and improvements to this software
including:

Joerg Albert	  Mathieu Lacage    Henry Qian	      giova+mwfdev@fagl
Vivien Chappelier Eric Lammerts	    Mark Rakes	      Stephen Walton
Tong Chia	  Stephane Laroche  Michael Renzmann  Dale Whitfield
Joachim Gleissner Georg Lukas	    Paul Stewart      Alexander Wirtz
Guy Erb		  Tom Marshall	    D. Stolte	      Kevin Yu
Kristian Hoffmann Nick Moss	    Bindu Therthala   Thorsten von Eicken
William S. Kish	  Nick Petroni      Carl Thompson     Jouni Malinen
Satish Balay      Richard Dawe      Bruno Randolf     Sebastian Weitzel
Rajendra Singh    Tai-hwa Liang     Divy Le Ray       John Bicket
Takayuki Kaiso    

(Apologies to anyone whose name was unintentionally left off.)

Feedback and Contributions
==========================
This project is hosted at http://madwifi.sourceforge.net.  Fixes and
enhancements are encouraged.  Please send all bug reports about this
driver to:

	[email protected]

When sending a problem report be sure to include the version of the
driver and the part identification the driver prints to the console when
the module is loaded.  For example,

ath_hal: 0.8.2.0
wlan: 0.7.0.0
ath_pci: 0.8.2.0
PCI: Found IRQ 11 for device 00:13.0
ath0: 11a rates: 6Mbps 9Mbps 12Mbps 18Mbps 24Mbps 36Mbps 48Mbps 54Mbps
ath0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps
ath0: 802.11 address: 00:05:5d:6f:99:5f
ath0: Atheros 5211: mem=0xfebf0000, irq=11

This says the HAL module is version 0.8.2, the wlan module is version
0.7, the driver is version 0.8.2 and the hardware uses an Atheros
5211 chip (which supports 11a and 11b modes).

We will try to respond in a timely manner but understand this software
is provided as-is; i.e. with no promise of support.