man/man4/atw.4

.\"     $OpenBSD: atw.4,v 1.40 2022/02/18 10:24:32 jsg Exp $
.\"	$NetBSD: atw.4,v 1.8 2004/06/06 04:05:49 wiz Exp $
.\"
.\" Copyright (c) 2003
.\"	David Young <dyoung@NetBSD.org>. All rights reserved.
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.Dd $Mdocdate: February 18 2022 $
.Dt ATW 4
.Os
.Sh NAME
.Nm atw
.Nd ADMtek ADM8211 IEEE 802.11b wireless network device
.Sh SYNOPSIS
.Cd "atw* at cardbus?"
.Cd "atw* at pci?"
.Sh DESCRIPTION
The
.Nm
driver supports PCI/CardBus 802.11b wireless adapters based on the
ADMtek ADM8211.
.Pp
The ADM8211 is a bus-mastering 802.11 Media Access Controller (MAC)
which is derived from ADMtek's DEC/Intel 21143 clones (see
.Xr dc 4
for more information).
It supports contention-free traffic (with an 802.11 Point Coordinator).
The ADM8211 integrates an RF3000 baseband processor (BBP) by RF
Microdevices.
.Pp
In a typical application, the ADM8211 is coupled with an RF front-end
by RFMD and a Silicon Laboratories Si4126 RF/IF synthesizer.
.Pp
With the ADM8211, the division of labor between the host and NIC
is different than with firmware-based NICs such as
.Xr an 4
and
.Xr 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.
.Pp
These are the modes the
.Nm
driver can operate in:
.Bl -tag -width "IBSS-masterXX"
.It BSS mode
Also known as
.Em infrastructure
mode, this is used when associating with an access point, through
which all traffic passes.
This mode is the default.
.It IBSS mode
Also known as
.Em IEEE ad-hoc
mode or
.Em peer-to-peer
mode.
This is the standardized method of operating without an access point.
Stations associate with a service set.
However, actual connections between stations are peer-to-peer.
.El
.Pp
The
.Nm
driver can be configured to use hardware
Wired Equivalent Privacy (WEP)
(though see
.Sx BUGS ,
below).
It is strongly recommended that WEP
not be used as the sole mechanism
to secure wireless communication,
due to serious weaknesses in it.
.Pp
In BSS mode,
the driver supports powersave mode,
which can be enabled via
.Xr ifconfig 8 .
.Pp
The
.Nm
driver can be configured at runtime with
.Xr ifconfig 8
or on boot with
.Xr hostname.if 5 .
.Sh HARDWARE
The
.Nm
driver supports PCI and CardBus cards using revisions 0x11 and 0x15
of the ADM8211 (aka ADM8211A) and revision 0x20 (aka ADM8211B).
This includes:
.Pp
.Bl -tag -width Ds -offset indent -compact
.It 3Com OfficeConnect 3CRSHPW796 CardBus
.It Belkin F5D6001 PCI (version 2 only)
.It Blitz NetWave Point CardBus
.It D-Link DWL-650 Rev. \&L1 CardBus
.It D-Link DWL-520 Rev. \&C1 PCI
.It LanReady WP2000 PCI
.It SMC 2635W CardBus (version 1 only)
.It TRENDnet TEW-221PC CardBus
.It Xterasys XN2511B PCI
.El
.Pp
The
.Nm
driver does not yet support cards using revision 0x30 (ADM8211C).
.\"This includes:
.\".Pp
.\".Bl -tag -width Ds -offset indent -compact
.\".El
.Sh EXAMPLES
The following example scans for available networks:
.Pp
.Dl # ifconfig atw0 scan
.Pp
The following
.Xr hostname.if 5
example configures atw0 to join network
.Dq mynwid ,
using WEP key
.Dq mywepkey ,
obtaining an IP address using DHCP:
.Bd -literal -offset indent
join mynwid nwkey mywepkey
inet autoconf
.Ed
.Sh DIAGNOSTICS
.Bl -diag
.It "atw0: failed to tune channel N"
The driver failed to tune the radio to a new channel.
The radio remains tuned to the old channel.
.It "atw0: atw_si4136_write wrote XXXX, 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.
.It "atw0: device timeout"
The ADM8211 failed to generate an interrupt to acknowledge a transmit
command.
.El
.Sh SEE ALSO
.Xr arp 4 ,
.Xr cardbus 4 ,
.Xr ifmedia 4 ,
.Xr intro 4 ,
.Xr netintro 4 ,
.Xr pci 4 ,
.Xr hostname.if 5 ,
.Xr ifconfig 8
.Rs
.%T Silicon Laboratories
.%U https://www.silabs.com
.Re
.Sh HISTORY
The
.Nm
device driver first appeared in
.Ox 3.6 .
.Sh AUTHORS
.An -nosplit
The
.Nm
driver was written by
.An David Young Aq Mt dyoung@NetBSD.org .
For features which the ADM8211 has in common with the DECchip 21x4x,
code was liberally borrowed from the
.Nx
tlp driver by
.An Jason Thorpe Aq Mt thorpej@NetBSD.org .
.Sh BUGS
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,
network performance may suffer.
.Pp
The driver does not provide rate control when the media type is
set to autoselect.
.Pp
The driver will sometimes complain that it cannot re-tune the radio
because the transmit process has not gone idle.
The author is investigating.
.Pp
Many features are still missing, especially WEP decryption and
802.11 power-saving.
.Pp
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.
.Pp
The driver is untested in the ad-hoc demo mode of Lucent WaveLAN
cards.
.Pp
The ADM8211 supports 802.11 power-saving; however,
.Nm
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.
.Pp
Combinations of an ADM8211 with either an Intersil or a Marvell RF
front-end are not supported.
.Pp
.Nm
contains incomplete support for the ADM8211's WEP encryption/decryption
engine.
.Nm
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 4 104-bit
shared WEP keys, the ADM8211 will store WEP key pairs for up to 20
peers.
The documentation provides no details, hence
.Nm
does not support the 20 key-pairs.