Atheros wireless driver support

Location

Primary development is now in FreeBSD-HEAD.

Why?

This work attempts to bring in fixes both from Linux ath9k (from the wireless-testing branch), the Atheros HAL code (not currently open source) and from local testing.

The eventual aim is to support all current and past Atheros wireless devices with a clean, portable, documented driver and HAL.

HAL

Please see the HAL device page for more information.

Supported Hardware

Please see the Hal Hardware Support Page for more information.

Operating Modes

802.11a (5GHz)
802.11bg (2GHz)
Half and Quarter rate modes in 5GHz for AR5212 family NICs
Turbo (static 40mhz mode) for AR5212 family NICs
900mhz NIC support (TODO: which NICs)
802.11na (5GHz) and 802.11ng (2.4GHz), 1 and 2 stream operation (MCS0-15), HT/20 and HT/40 channel width

Rate Control

TODO

Ambient Noise Immunity (ANI)

Please see the ANI page for more information.

DFS/Radar Detection

The DFS machinery is driven by code in the net80211 stack. The driver simply reports that a radar event has been detected.

At this stage, ath(4) does not support radar detection. This may change in the future.

For an introduction to the radar detection/classification information currently available, please see the HAL Radar Detection page. This includes links to some relevant Atheros Patents.

802.11n support

Please see the dev/ath(4)/80211n page for further information.

Bug List

Check FreeBSD GNATS for bugs filed to freebsd-wireless

Work in progress

net80211 A-MPDU/A-MSDU TX support - STA	Unimplemented	Needs implementing
net80211 A-MPDU/A-MSDU TX support - AP	Unimplemented	Needs implementing
ath 11n TX support	In progress	Basic 11n TX seems to work - no A-MPDU/A-MSDU is implemented. HT40/ShortGI works.
ath 11n protection	Buggy - In Progress	There's no legacy protection for 11n frames. Investigate and fix!
RIFS	Unimplemented	Unimplemented
Radar Detection	In progress	Unimplemented
AR9285 PCIe LOCAL_TIMEOUT	Investigation	Some people w/ AR9285's are seeing LOCAL_TIMEOUT errors (which are currently not fatal); add some debugging code to see what kinds of circumstances trigger these and try to repair it

Small Project Wish List

The following is a set of simple projects which interested developers can use to get familiar with the ath/hal codebase.

Bluetooth Coexistence for AR9280/AR9285 - port ath9k btcoex routines and add some debugging to ensure it's actually functioning.
RFKill for AR5416 and later (both software and hardware) - investigate how it's done for the previous chipsets (AR5212 in particular) and what ath9k does; then plan out a implementation and testing plan.
Tidy up the build structure for the ath tools so they can be included in the system by default?
Modify if_ath.c to report the per-radio control/extension noise floor and RSSI - net80211 has already been taught about it, ath_hal has been taught about how to export the statistics; all that's needed is the glue in if_ath.c.

Larger Project Wish List

Support channel busy surveys (a la mac80211.)
(Re) Test Quarter/Half rate support for the AR5212/AR5213 and derivatives.
(Re) Test long link support for AR5212/AR5213 and derivatives - this essentially tweaks the ACK, RTS, CTS and various IFS timings to support long distance links.
Implement Quarter/Half rate support for AR5416 and later chipsets - non-11n and 11n modes.
Implement long link support for AR5416 and later chipsets
(Re) Test TDMA support for AR5212/AR5213 and derivatives.
Implement TDMA support for AR5416 and later chipsets - non-11n and 11n modes.
Investigate and fix power saving mode(s).
ATIM?
Auto-sleep support in AR9280 and later?
AR9271 and USB support in the HAL - a pre-requisite for supporting the 11n NICs after the AR9170-based devices.
Implement per-packet TPC (Transmission Power Control) for chipsets which support it - required for full DFS support.

= Completed Wish List ==

Implement software TX aggregation and retransmit for AR5416 and later chipsets in 11n mode.
The HAL configuration variables are global (eg debug, beacon timer adjustments, ALQ logging.) It would be nice to have these per-HAL instance - so move them to the public part of the ath_hal struct and initialise them on device attach. They're not per-vif; they're per-device.
I've added quite a few more statistics to the per-device ioctl statistics (sys/dev/ath/if_athioctl.h); athstats needs to be taught about these new statistics so they can be reported.

Fixed Issues

ath multi-SSID support - < AR5416	Fixed	This needs testing - both open and WEP/WPA
ath multi-SSID support - >= AR5416	Fixed	There's bugs in the hardware encryption handling - this needs to be investigated and fixed!
ath multicast search key support	Fixed	Disabled in this codebase because the current code in -HEAD breaks AES/CCMP encryption, required for 802.11n. Find and repair the damage.
ath 11n RX support	Fixed	Basic 11n RX seems to work - A-MPDU/A-MSDU seems buggy and needs to be debugged
net80211 HT/20 support - 2.4ghz	Fixed	This is the current mode being used to test
net80211 HT/20 support - 5ghz	Fixed	Needs testing
net80211 HT/40 support	Fixed	Needs implementing
net80211 short-GI support	Fixed	Needs testing
net80211 11n STA mode	Fixed	This is being tested at the moment
net80211 11n AP mode	Fixed	Needs implementing
net80211 A-MPDU/A-MSDU RX support	Fixed	A-MPDU issues resolved; Ath cards require ampdudensity of 8

Useful Links

Atheros Patent: Adaptive Noise Immunity: http://www.freepatentsonline.com/7349503.html
Atheros Patent: Noise Floor Calibration / Signal Strength Detection: http://www.freepatentsonline.com/7245893.html
Atheros Patent: Offset/Gain calibration for ADCs: http://www.freepatentsonline.com/7541952.html
Atheros Patent: Radar Pulse Detection/Estimation: http://ip.com/patent/US6891496
May 2008 IEEE: Atheros 2.4/5 Ghz 2x2 MIMO SoC (talk slides?): http://www.ewh.ieee.org/r6/scv/ssc/May2008_WLAN.pdf