NAME    [Toc]    [Back]

     atw - ADMtek ADM8211 802.11 wireless network driver

SYNOPSIS    [Toc]    [Back]

     atw* at cardbus? function ?
     atw* at pci? dev ? function ?

DESCRIPTION    [Toc]    [Back]

     The  atw  driver  supports  PCI/Cardbus   802.11b   wireless
adapters based on
     the ADMtek ADM8211.

     The  ADM8211  is  a  bus-mastering  802.11 Media Access Controller (MAC) which
     is derived from ADMtek's DEC/Intel 21143 clones (see dc(4)).
It supports
     contention-free  traffic (with an 802.11 Point Coordinator),
64/128-bit
     WEP encryption, and 802.11 power-saving.  The ADM8211  integrates an
     RF3000 baseband processor (BBP) by RF Microdevices.

     In  a typical application, the ADM8211 is coupled with an RF
front-end by
     RFMD and a Silicon Laboratories Si4126 RF/IF synthesizer.

     With the ADM8211, the division of labor between the host and
NIC is different
  than with firmware-based NICs such as an(4), awi(4),
and wi(4).
     The ADM8211 is still responsible for real-time 802.11  functions such as
     sending  ACK/RTS/CTS/ATIM  frames,  sending beacons, and answering CF polls
     from the access point, but the host takes responsibility for
providing
     802.11  functions such as scanning, association, and authentication.  The
     host is also responsible for programming both  the  BBP  and
the RF/IF synthesizer.


     atw  contains  incomplete  support for the ADM8211's WEP encryption/decryption
 engine.  atw does not yet support hardware WEP  decryption, however,
     it will use the ADM8211's crypto engine to encrypt transmitted frames.
     Documentation from ADMtek claims that, in addition to the  4
128-bit
     shared WEP keys, the ADM8211 will store WEP key pairs for up
to 20 peers.
     The documentation provides no details, hence  atw  does  not
support the 20
     key-pairs.

     The  ADM8211 operates in 802.11 infrastructure mode (with an
access point)
     and in 802.11 ad hoc mode (without an access point) at 1, 2,
5.5, and
     11Mbps.   ADMtek  says that the ADM8211 cannot operate as an
access point.

     The operating mode is selected using the ifconfig(8)  utility.  For more
     information  on configuring this device, see ifconfig(8) and
ifmedia(4).

HARDWARE    [Toc]    [Back]

     The atw driver supports PCI and Cardbus cards using revision
0x11 and
     0x15 of the ADM8211 (aka ADM8211A).  This includes:

           3Com OfficeConnect 3CRSHPW796 Cardbus card
           Belkin F5D6001 PCI card
           Blitz NetWave Point Cardbus card
           D-Link DWL-650 Rev. L1 Cardbus card
           D-Link DWL-520 Rev. C1 PCI card
           LanReady WP2000 PCI card
           TrendNet TEW-221PC Cardbus card
           Xterasys XN2511B PCI card

     The  atw  driver  does  not yet support cards using revision
0x20 (ADM8211B)
     or 0x30 (ADM8211C).  This includes:

           SMC 2635W Cardbus card

DIAGNOSTICS    [Toc]    [Back]

     atw0: failed to tune channel %d  The driver failed  to  tune
the radio to a
     new channel.  The radio remains tuned to the old channel.

     atw0:  atw_si4136_write  wrote  %08x, SYNCTL still busy  The
driver waited
     100ms without seeing an indication that the ADM8211 had finished writing
     a register on the Si4126 RF/IF synthesizer.

     atw0:  device timeout  The ADM8211 failed to generate an interrupt to acknowledge
 a transmit command.

SEE ALSO    [Toc]    [Back]

     an(4), arp(4), cardbus(4), ifmedia(4), netintro(4),  pci(4),
wi(4),
     ifconfig(8)

     ADMtek, http://www.admtek.com.tw.

     Silicon Laboratories, http://www.silabs.com.

     RF Micro Devices, http://www.rfmd.com.

HISTORY    [Toc]    [Back]

     The atw device driver first appeared in OpenBSD 3.6.

AUTHORS    [Toc]    [Back]

     The  atw  driver  was  written  by David Young <[email protected]>.  For features
 which the ADM8211  has  in  common  with  the  DECchip
21x4x, code was
     liberally borrowed from the NetBSD tlp driver by
     Jason Thorpe <[email protected]>.

BUGS    [Toc]    [Back]

     The author does not fully understand what processing the duration fields
     for the PLCP header and the  802.11  header  undergo  before
they are applied
     to a transmitted frame.  If the duration fields in transmitted frames are
     incorrect, the performance of your network may suffer.

     The driver does not provide rate control when the media type
is set to
     autoselect.

     The  driver  lets you change to hostap mode, but it does not
work and it
     probably never will.

     The driver will sometimes complain that  it  cannot  re-tune
the radio because
 the transmit process has not gone idle.  The author is
investigating.


     Many features are still missing, especially  WEP  decryption
and 802.11
     power-saving.

     The  ad hoc mode has not been rigorously tested.  IBSSs with
the same SSID
     may not coalesce, but this should not matter for most applications.

     The  driver  is  untested  in the ad-hoc demo mode of Lucent
WaveLAN cards.

     The ADM8211 supports 802.11 power-saving, however, atw  does
not support
     it yet.  For time-bounded service, the ADM8211 will interoperate with an
     access point which implements the 802.11 Point  Coordination
Function,
     however, this is also not supported.

     Combinations of an ADM8211 with either an Intersil or a Marvell RF frontend
 are not supported.

OpenBSD      3.6                           June      5,      2004