a1655g-rfkill
-------------

This a Linux kernel module which provides an rfkill driver for the wifi
antenna on Fujitsu Siemens Amilo A1655G laptop. It allows userspace programs
to turn on/off the antenna through the kernel's rfkill interface. This
module was made possible by the earlier fsaa1655g module by Martin Vacera,
to whom I'm very grateful for giving my laptop the ability to talk to the
world for the past 5 years :-)

Note that this driver is only compatible with modern 2.6 kernels. If you're
using a 2.4 kernel (anyone?) then you'll need the original fsaa1655g.

Compiling and Installing
------------------------

In adition to the usual compilation tools (gcc, make) you'll need the
headers for the kernel running on your system. This is usually provided by
your distro, e.g. for Debian 64bit:

$ sudo aptitude install linux-headers-2.6-amd64

You should then be able to compile the module:

$ make

and install it:

$ sudo make install

Usage
-----

Once installed, you can load the module into your kernel in the usual way:

sudo modprobe a1655g-rfkill

If the module loaded successfully, you should see a couple of lines like this
in dmesg:

[ 6989.378502] a1655g-rfkill: Registering as a platform device
[ 6989.383242] a1655g-rfkill: Turning WLAN radio ON

The rfkill subsystem should default to switching on the antenna unless your
system is configured otherwise. You can also explicitly turn the antenna on
and off from the command line using the rfkill userspace tool:

$ sudo aptitude install rfkill
$ rfkill list
0: phy0: Wireless LAN
	Soft blocked: no
	Hard blocked: no
1: a1655g-rfkill: Wireless LAN
	Soft blocked: no
	Hard blocked: no
$ rfkill block 1
[Wlan LED should go off]
$ rfkill list
0: phy0: Wireless LAN
	Soft blocked: no
	Hard blocked: yes
1: a1655g-rfkill: Wireless LAN
	Soft blocked: yes
	Hard blocked: no
$ rfkill unblock 1
[Wlan LED should come back on]
$ rfkill list
0: phy0: Wireless LAN
        Soft blocked: no
        Hard blocked: no
1: a1655g-rfkill: Wireless LAN
        Soft blocked: no
        Hard blocked: no

There are also GUI interfaces to rfkill (e.g.
http://http://gitorious.org/gnome-rfkill-applet)

fsaa1655g Already Exists - Why Do It Again?
-------------------------------------------

There are two motivations: the first is that fsaa1655g only allows
manual/scripted control over the wifi radio switch; implementing an rfkill
interface allows the kernel to automatically manage the switch in most
circumstances, e.g. reenabing wlan when coming out of hibernate etc. The
second motivation is more personal: I'm new to kernel development, and the
simple nature of the task makes it a nice introduction to writing a complete
functioning kernel module that does something useful :-)

--
Phil Stewart
May 2011

Email: phil.stewart@lichp.co.uk