MFC r342966:
net80211: fix possible panic for some drivers after r342465

Check if rate control structures were allocated before trying to
access them in various places; this was possible before on
allocation failure (unlikely), but was revealed after r342211
where allocation was deferred.

The patch was adjusted a bit since file contents are different enough
since r306591.

Also, 'rate_stats' sysctl is not available here, so the panic is
unlikely to happen here even without this patch.

MFC r321401:
net80211: do not allow to unload rate control module if it is still in use.

Keep 'nrefs' counter up-to-date, so 'kldunload wlan_amrr' with 1+ active
wlan(4) interface will not lead to kernel panic.

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Document the current 11n rate selection shortcoming in the AMRR code.

Implement basic 802.11n awareness in the PHY and AMRR rate control code.

* Add 802.11n 2ghz and 5ghz tables, including legacy rates and up to
MCS23 rates (3x3.)

* Populate the rate code -> rate index lookup table with MCS _and_
normal rates, but _not_ the basic rate flag. Since the basic rate flag
is the same as the MCS flag, we can only use one.

* Introduce some accessor inlines that do PLCP and rate table lookup/access
and enforce that it doesn't set the basic rate bit. They're not
designed for MCS rates, so it will panic.

* Start converting drivers that use the rate table stuff to use the
accessor inlines and strip the basic flag.

* Teach AMRR about basic 11n - it's still as crap for MCS as it is
being used by iwn, so it's not a step _backwardS_.

* Convert iwn over to accept 11n MCS rates rather than 'translate' legacy
to MCS rates. It doesn't use a lookup table any longer; instead it's a
function which takes the current node (for HT parameters) and the
rate code, and returns the hardware PLCP code to use.

Tested:

* ath - it's a no-op, and it works that way
* iwn - both 11n and non-11n

sysctl(9) cleanup checkpoint: amd64 GENERIC builds cleanly.

Commit the net* piece.

When in the RUN -> AUTH -> RUN FSM transition happens, we'll call the
ratectl_node_init() functions and since ni_rtctls was already
malloc'ed() we will panic. Fix this by using the already malloc'ed
pointer.

Found by: bschmidt
Reviewed by: bschmidt

Use M_NOWAIT instead of M_WAITOK to avoid race conditions.

MFC after: 1 month

net80211 rate control framework (net80211 ratectl).

This framework allows drivers to abstract the rate control algorithm and
just feed the framework with the usable parameters. The rate control
framework will now deal with passing the parameters to the selected
algorithm. Right now we have AMRR (the default) and RSSADAPT but there's
no way to select one with ifconfig, yet.
The objective is to have more rate control algorithms in the net80211
stack so all drivers[0] can use it. Ideally, we'll have the well-known
sample rate control algorithm in the net80211 at some point so all
drivers can use it (not just ath).

[0] all drivers that do rate control in software, that is.

Reviewed by: bschmidt, thompsa, weyongo
MFC after: 1 months

Multi-bss (aka vap) support for 802.11 devices.

Note this includes changes to all drivers and moves some device firmware
loading to use firmware(9) and a separate module (e.g. ral). Also there
no longer are separate wlan_scan* modules; this functionality is now
bundled into the wlan module.

Supported by: Hobnob and Marvell
Reviewed by: many
Obtained from: Atheros (some bits)

Update 802.11 wireless support:
o major overhaul of the way channels are handled: channels are now
fully enumerated and uniquely identify the operating characteristics;
these changes are visible to user applications which require changes
o make scanning support independent of the state machine to enable
background scanning and roaming
o move scanning support into loadable modules based on the operating
mode to enable different policies and reduce the memory footprint
on systems w/ constrained resources
o add background scanning in station mode (no support for adhoc/ibss
mode yet)
o significantly speedup sta mode scanning with a variety of techniques
o add roaming support when background scanning is supported; for now
we use a simple algorithm to trigger a roam: we threshold the rssi
and tx rate, if either drops too low we try to roam to a new ap
o add tx fragmentation support
o add first cut at 802.11n support: this code works with forthcoming
drivers but is incomplete; it's included now to establish a baseline
for other drivers to be developed and for user applications
o adjust max_linkhdr et. al. to reflect 802.11 requirements; this eliminates
prepending mbufs for traffic generated locally
o add support for Atheros protocol extensions; mainly the fast frames
encapsulation (note this can be used with any card that can tx+rx
large frames correctly)
o add sta support for ap's that beacon both WPA1+2 support
o change all data types from bsd-style to posix-style
o propagate noise floor data from drivers to net80211 and on to user apps
o correct various issues in the sta mode state machine related to handling
authentication and association failures
o enable the addition of sta mode power save support for drivers that need
net80211 support (not in this commit)
o remove old WI compatibility ioctls (wicontrol is officially dead)
o change the data structures returned for get sta info and get scan
results so future additions will not break user apps
o fixed tx rate is now maintained internally as an ieee rate and not an
index into the rate set; this needs to be extended to deal with
multi-mode operation
o add extended channel specifications to radiotap to enable 11n sniffing

Drivers:
o ath: add support for bg scanning, tx fragmentation, fast frames,
dynamic turbo (lightly tested), 11n (sniffing only and needs
new hal)
o awi: compile tested only
o ndis: lightly tested
o ipw: lightly tested
o iwi: add support for bg scanning (well tested but may have some
rough edges)
o ral, ural, rum: add suppoort for bg scanning, calibrate rssi data
o wi: lightly tested

This work is based on contributions by Atheros, kmacy, sephe, thompsa,
mlaier, kevlo, and others. Much of the scanning work was supported by
Atheros. The 11n work was supported by Marvell.

- Nuke unnecessary header.
- Make wlan_amrr depend on wlan, so that it can find various symbols in
wlan module if wlan is not compiled into kernel.

Approved by: sam (mentor)
Tested by: kevlo

device-independent implementation of AMRR tx rate control algorithm

Obtained from: openbsd (w/ mods)
MFC after: 1 month