[PATCH] bcm43xx: Update Documentation/bcm43xx.txt

The in-kernel documentation of the bcm43xx driver is out of date.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 75 insertions, 22 deletions

diff --git a/Documentation/networking/bcm43xx.txt b/Documentation/networking/bcm43xx.txt
index 28541d2bee1e..a136721499bf 100644
--- a/Documentation/networking/bcm43xx.txt
+++ b/Documentation/networking/bcm43xx.txt
@@ -2,35 +2,88 @@
                         BCM43xx Linux Driver Project
                         ============================
 
-About this software
--------------------
+Introduction
+------------
 
-The goal of this project is to develop a linux driver for Broadcom
-BCM43xx chips, based on the specification at 
-http://bcm-specs.sipsolutions.net/
+Many of the wireless devices found in modern notebook computers are
+based on the wireless chips produced by Broadcom. These devices have
+been a problem for Linux users as there is no open-source driver
+available. In addition, Broadcom has not released specifications
+for the device, and driver availability has been limited to the
+binary-only form used in the GPL versions of AP hardware such as the
+Linksys WRT54G, and the Windows and OS X drivers.  Before this project
+began, the only way to use these devices were to use the Windows or
+OS X drivers with either the Linuxant or ndiswrapper modules. There
+is a strong penalty if this method is used as loading the binary-only
+module "taints" the kernel, and no kernel developer will help diagnose
+any kernel problems.
 
-The project page is http://bcm43xx.berlios.de/
+Development
+-----------
 
+This driver has been developed using
+a clean-room technique that is described at
+http://bcm-specs.sipsolutions.net/ReverseEngineeringProcess. For legal
+reasons, none of the clean-room crew works on the on the Linux driver,
+and none of the Linux developers sees anything but the specifications,
+which are the ultimate product of the reverse-engineering group.
 
-Requirements
-------------
+Software
+--------
+
+Since the release of the 2.6.17 kernel, the bcm43xx driver has been
+distributed with the kernel source, and is prebuilt in most, if not
+all, distributions.  There is, however, additional software that is
+required. The firmware used by the chip is the intellectual property
+of Broadcom and they have not given the bcm43xx team redistribution
+rights to this firmware.  Since we cannot legally redistribute
+the firwmare we cannot include it with the driver. Furthermore, it
+cannot be placed in the downloadable archives of any distributing
+organization; therefore, the user is responsible for obtaining the
+firmware and placing it in the appropriate location so that the driver
+can find it when initializing.
+
+To help with this process, the bcm43xx developers provide a separate
+program named bcm43xx-fwcutter to "cut" the firmware out of a
+Windows or OS X driver and write the extracted files to the proper
+location. This program is usually provided with the distribution;
+however, it may be downloaded from
+
+http://developer.berlios.de/project/showfiles.php?group_id=4547
 
-1)      Linux Kernel 2.6.16 or later
-        http://www.kernel.org/
+The firmware is available in two versions. V3 firmware is used with
+the in-kernel bcm43xx driver that uses a software MAC layer called
+SoftMAC, and will have a microcode revision of 0x127 or smaller. The
+V4 firmware is used by an out-of-kernel driver employing a variation of
+the Devicescape MAC layer known as d80211. Once bcm43xx-d80211 reaches
+a satisfactory level of development, it will replace bcm43xx-softmac
+in the kernel as it is much more flexible and powerful.
 
-        You may want to configure your kernel with:
+A source for the latest V3 firmware is
 
-        CONFIG_DEBUG_FS (optional):
-                -> Kernel hacking
-                  -> Debug Filesystem
+http://downloads.openwrt.org/sources/wl_apsta-3.130.20.0.o
 
-2)      SoftMAC IEEE 802.11 Networking Stack extension and patched ieee80211
-        modules:
-        http://softmac.sipsolutions.net/
+Once this file is downloaded, the command
+'bcm43xx-fwcutter -w <dir> <filename>'
+will extract the microcode and write it to directory
+<dir>. The correct directory will depend on your distribution;
+however, most use '/lib/firmware'. Once this step is completed,
+the bcm3xx driver should load when the system is booted. To see
+any messages relating to the driver, issue the command 'dmesg |
+grep bcm43xx' from a terminal window. If there are any problems,
+please send that output to Bcm43xx-dev@lists.berlios.de.
 
-3)      Firmware Files
+Although the driver has been in-kernel since 2.6.17, the earliest
+version is quite limited in its capability. Patches that include
+all features of later versions are available for the stable kernel
+versions from 2.6.18. These will be needed if you use a BCM4318,
+or a PCI Express version (BCM4311 and BCM4312). In addition, if you
+have an early BCM4306 and more than 1 GB RAM, your kernel will need
+to be patched.  These patches, which are being updated regularly,
+are available at ftp://lwfinger.dynalias.org/patches. Look for
+combined_2.6.YY.patch. Of course you will need kernel source downloaded
+from kernel.org, or the source from your distribution.
 
-        Please try fwcutter. Fwcutter can extract the firmware from various 
-        binary driver files. It supports driver files from Windows, MacOS and 
-        Linux. You can get fwcutter from http://bcm43xx.berlios.de/.
-        Also, fwcutter comes with a README file for further instructions.
+If you build your own kernel, please enable CONFIG_BCM43XX_DEBUG
+and CONFIG_IEEE80211_SOFTMAC_DEBUG. The log information provided is
+essential for solving any problems.