Wrap ieee80211_add_channel_list_2ghz into another function
which supplies default (1-14) channel list to it and drop
its copies from drivers.
Checked with RTL8188EE, country US / JP / KR / UA.
MFC after: 2 weeks
Since r287197 ieee80211com is a part of drivers softc; as a result,
after detach all pointers to it (iv_ic, ni_ic) are invalid. Most
possible users (tasks, interrupt handlers) are blocked / removed
when device is stopped; however, ioctl handlers were not tracked
and may crash if ieee80211com structure is accessed.
Since ieee80211com pointer access from ieee80211vap structure is not
protected by lock (constant after interface creation) and used in
many other places just use reference counting for ioctl handlers;
on detach set 'detached' flag and wait until reference counter goes to 0.
For HEAD ieee80211vap size was changed (__FreeBSD_version bumped);
however, in stable branches I'm going to split / reuse the last
iv_spare field for KBI stability.
Tested with:
- rsu(4), SIOCSIFCAP (-rxcsum) ioctl;
- rtwn_pci(4), SIOCG80211 / IEEE80211_IOC_HTPROTMODE ioctl.
MFC after: 1 week
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.
The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
No functional change intended.
As part of (eventual) p2p/tdls/multi-STA support, a lot of global configuration
parameters (WME, ERP (slot, preamble), channel width, HT protmode, etc are the
biggest offenders) should be per-VAP.
For multi-BSS VAP operation they may be linked, but for p2p/TDLS
operation that can be off-channel they can definitely be different
(think: 2GHz STA, 5GHz p2p.)
The global configuration view of these is mostly a "configure the current
non-smart-firmware NIC" view. This should be split up into per-VAP state,
then a global non-smart-firmware-NIC management layer to handle channel
changes and such in software.
This is step one in a loooong road for this. It should be a big non-functional
change for everyone.
* create a per-VAP WME update call.
* call it if its set, and call the global callback if it isn't
This still uses global WME state - it's just preparation for a future change
which will make the WME state per-VAP and fall through to a shared WME
configuration for hostap operation.
Note: this requires a full kernel recompile; the internal net80211 ABI has changed.
Reviewed by: avos
Differential Revision: https://reviews.freebsd.org/D9986
ucast/mcast/mgmt HT rate.
- Init global ieee80211_htrateset only once; neither ic_htcaps nor
ic_txstream is changed when device is attached;
- Move global ieee80211_htrateset structure to ieee80211com;
there was a possible data race when more than 1 wireless device is
used simultaneously;
- Discard unsupported rates in ieee80211_ioctl_settxparams(); otherwise,
an unsupported value may break connectivity (actually,
'ifconfig wlan0 ucastrate 8' for RTL8188EU results in immediate
disconnect + infinite 'device timeout's after it).
Tested with:
- Intel 6205, STA mode.
- RTL8821AU, STA mode.
Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D9871
* on the station side, only call the quiet time IE method if we have a
quiet IE - otherwise call the NULL method once, and then don't waste
time calling NULL
* on the beacon generation side - force a beacon regeneration each time
quiet time is enabled/disabled. Without this, enabling/disabling quiet
time IE would cause the beacon contents to be corrupted since none of
the "move contents around" logic (like for CSA and TIM handling) is implemented.
This changes the size of ieee80211_node so it requires a kernel recompile,
but no userland recompile.
Tested:
* AR9380, AP mode, enabling/disabling quiet time IE
* AR9380, STA mode, with upcoming driver changes.
Flags
- IEEE80211_F_ASCAN
- IEEE80211_F_SIBSS
- IEEE80211_F_IBSSON
are not used since r170530 (old WI compatibility ioctls removal)
and r178354 (removed from other places).
IEEE80211_F_TXPOW_FIXED was never utilized; initially added with
IEEE80211_F_TXPOW_AUTO / IEEE80211_F_TXPOW_OFF flags,
which were replaced with IEEE80211_C_TXPMGT capability check in r138568.
Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D9369
* allocate an ext bit for fragment offload. Some NICs (like the ath10k
hardware in native wifi or 802.3 mode) support doing packet fragmentation
in firmware/hardware, so we don't have to do it here.
* allocate an ext bit for VHT and start using it.
I added IEEE80211_TX_LOCK() a few years ago because there were races between
seqno allocation, driver queuing and crypto IV allocation. This meant that
they'd appear out of sequence and the receiver would drop them, leading to
terrible performance or flat out traffic hangs.
This flag should be set by drivers that do their own sequence number
allocation for all frames it needs to happen for, including beacon frames.
Eventually this should lead to the driver taking care of locking for
allocating seqno and other traffic-triggered events (eg addba setup.)
The 11n code uses these bits for both configuration /and/ controlling
the channel width on softmac chips - it uses it to find the widest
width for all VAPs (eg a HT20 vap and a HT40 vap) to know what to
configure the ic_curchan.
For fullmac devices it isn't /as/ important, as each virtual device
exposed by the firmware will likely have its own configuration and the
firmware figures out what to do to enable it.
* rename the ieee80211com field for vht mcsinfo to be ic_, not iv;
* add a vht config field, stealing from the spares I left there.
This doesn't change the ABI.
The ath10k firmware supports hardware WEP offload, and in native wifi mode
(or 802.3 ethernet mode, for that matter) the WEP key isn't actually included
in the TX payload from net80211. Instead, a separate firmware command is issued
that sets the default TX key to be the specified key.
However, net80211 doesn't at all inform the driver layer that this is
occuring - it just "expects" to be inserting WEP header information
when doing WEP TX, even with hardware encryption.
So, to better support the newer world order, turn the default TX key assignment
into a VAP method that can be overridden by the driver and ensure its wrapped
in a crypto begin/end set. That way it should be correctly atomic from the
point of view of keychanges (as long as the driver does the right thing.)
It'd be nice if we passed through to the key_set call a flag that says
"also make this the default key" - that's captured here by calling the
deftxkey method after the key_set method. Maybe I can do that later.
Note: this is a net80211 ABI change, and will require a kernel+modules
recompile. Happy Holidays, etc.
Tested:
* ath10k driver port
* rtwn_usb, WEP station
This is a work in progress and some of this stuff may change;
but hopefully I'm laying down enough stuff and space in fields
to allow it to grow without another major recompile.
We'll see!
* Add a net80211 PHY type for VHT 2G and VHT 5G.
Note - yes, VHT is supposed to be for 5GHZ, however some vendors
(*cough* most of them) support some subset of VHT rate support
in 2GHz. No - not 80MHz wide channels, but at least some MCS8-9
support, maybe some beamforming, and maybe some longer A-MPDU
aggregates. I don't want to even think about MU-MIMO on 2GHz.
* Add an ifmedia placeholder type for VHT rates.
* Add channel flags for VHT, VHT20/40U/40D/80/80+80/160
* Add channel macros for the above
* Add ieee80211_channel fields for the VHT information and flags,
along with some padding (so this struct definitely grows.)
* Add a phy type flag for VHT - 'v'
* Bump the number of channels to a much higher amount - until we get
something like the linux mac80211 chanctx abstraction (where the
stack provides a current channel configuration via callbacks,
versus the driver ever checking ic->ic_curchan or similar) we'll
have to populate VHT+HT combinations.
Eg, there'll likely be a full set of duplicate VHT20/40 channels to match
HT channels. There will also be a full set of duplicate VHT80 channels -
note that for VHT80, its assumed you're doing VHT40 as a base, so we
don't need a duplicate of VHT80 + 20MHz only primary channels, only
a duplicate of all the VHT40 combinations.
I don't want to think about VHT80+80 or VHT160 for now - and I won't,
as the current device I'm doing 11ac bringup on (QCA9880) only does
VHT80.
I'll likely revisit the channel configuration and scanning related
stuff after I get VHT20/40 up.
* Add vht flags and the basic MCS rate setup to ieee80211com, ieee80211vap
and ieee80211_node in preparation for 11ac configuration.
There is zero code that uses this right now.
* Whilst here, add some more placeholders in case I need to extend
out things by some uint32_t flag sized fields. Hopefully I won't!
What I haven't yet done:
* any of the code that uses this
* any of the beamforming related fields
* any of the MU-MIMO fields required for STA/AP operation
* any of the IE fields in beacon frame / probe request/response handling
and the calculations required for shifting beacon contents around
when the TIM grows/shrinks
This will require a full rebuild of net80211 related programs -
ifconfig, hostapd, wpa_supplicant.
* ic_freq is the centre of the primary channel, not the centre of the
HT40/HT80/etc channel. Add a method to access that.
* Add a method to access the centre of the primary channel, including
knowing the centre of the 5/10/20/40/80, versus the primary channel.
Ie, it's the centre of the 40, 80, 160MHz channel.
* Add a method to access the centre frequency of the secondary 80MHz
channel - we don't support VHT yet, but when we do.
* Add methods to access the current channel and the per-dev desired
channel. Ideally drivers that do full offload with a per-vap channel
configuration should use the vap channel, NOT ic_curchan.
Non-offload drivers that require net80211 to change the channel should
be accessing ic_curchan.
This is a very simple addition to the net80211 scan support.
It doesn't implement a replacement scan interface - it just disables
the pieces that we should disable to make this lifecycle a bit
more managable.
There's more work to come before full scan offload support is available
but it should be good enough for driver work.
* add a flag to say "full offload"
* don't do probe requests when scanning full-offload - firmware can do that
* don't do powersave transitions and buffering - firmware can do that
tested:
* iwm(4) - STA mode
* ath10k port (local, not in freebsd-head yet)
Reviewed by: avos
Differential Revision: https://reviews.freebsd.org/D8262
Add new lock for stageq (part of ieee80211_superg structure) and
ni_tx_superg (part of ieee80211_node structure);
drop com_lock protection where it is used to protect them.
While here, drop duplicate OPACKETS counter incrementation.
ni_tx_ampdu is not protected with it (however, it is also used without
locking in other places; probably, it requires some other solution
to be thread-safe).
Tested with RTL8188CUS (AP) and RTL8188EU (STA).
NOTE: Since this change breaks KBI, all wireless drivers need to be
recompiled.
Reviewed by: adrian
Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D6958
Replace ifnet list lookup (which is broken since r287197, because
IFT_IEEE80211 type is not used anymore) with iteration on
ieee80211com list.
Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D6419
This change adds few methods for net80211 channel table setup:
- ieee80211_add_channel()
- ieee80211_add_channel_ht40()
(primarily for drivers, that parse EEPROM to get channel list -
they will allow to hide implementation details).
- ieee80211_add_channel_list_2ghz()
- ieee80211_add_channel_list_5ghz()
(mostly as a replacement for ieee80211_init_channels() - they will allow
to specify non-default channel list; may be used in ic_getradiocaps()).
Tested with wpi(4) (add_channel) and rum(4) (add_channel_list_2ghz).
Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D6124
do software A-MSDU encapsulation.
Right now there's AMSDU TX/RX capability bits and they're mostly
unused, however I'd like to maintain those as the general configuration,
not also "please software encap AMSDU." For platforms that can do
A-MSDU in firmware (iwn, iwm, etc) then their init paths can read
this flag to configure A-MSDU.
For hz=1000 any number, greater than 4194 causes integer overflow;
this change casts the number to uint64_t before operating with it.
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D5268
we're assuming hz=1000 and not gracefully handling when it isn't.
The math involved will return 0 for hz < 1000, which it is on some
platforms and on DragonflyBSD.
This doesn't fix it, it:
* converts one manual use over to use the macro, and
* comments where it needs some thought/fixing.
I'll think about this a bit more before fixing it.
Submitted by: imre@vdsz.com
This call may be used when device cannot continue to operate normally
(e.g., throws firmware error, watchdog timer expires)
and need to be restarted.
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D3998
The MAC can be fetched from the key struct.
I added the ndis updates to make it compile.
Submitted by: <s3erios@gmail.com>
Differential Revision: https://reviews.freebsd.org/D3657
connectivity interact with the net80211 stack.
Historical background: originally wireless devices created an interface,
just like Ethernet devices do. Name of an interface matched the name of
the driver that created. Later, wlan(4) layer was introduced, and the
wlanX interfaces become the actual interface, leaving original ones as
"a parent interface" of wlanX. Kernelwise, the KPI between net80211 layer
and a driver became a mix of methods that pass a pointer to struct ifnet
as identifier and methods that pass pointer to struct ieee80211com. From
user point of view, the parent interface just hangs on in the ifconfig
list, and user can't do anything useful with it.
Now, the struct ifnet goes away. The struct ieee80211com is the only
KPI between a device driver and net80211. Details:
- The struct ieee80211com is embedded into drivers softc.
- Packets are sent via new ic_transmit method, which is very much like
the previous if_transmit.
- Bringing parent up/down is done via new ic_parent method, which notifies
driver about any changes: number of wlan(4) interfaces, number of them
in promisc or allmulti state.
- Device specific ioctls (if any) are received on new ic_ioctl method.
- Packets/errors accounting are done by the stack. In certain cases, when
driver experiences errors and can not attribute them to any specific
interface, driver updates ic_oerrors or ic_ierrors counters.
Details on interface configuration with new world order:
- A sequence of commands needed to bring up wireless DOESN"T change.
- /etc/rc.conf parameters DON'T change.
- List of devices that can be used to create wlan(4) interfaces is
now provided by net.wlan.devices sysctl.
Most drivers in this change were converted by me, except of wpi(4),
that was done by Andriy Voskoboinyk. Big thanks to Kevin Lo for testing
changes to at least 8 drivers. Thanks to pluknet@, Oliver Hartmann,
Olivier Cochard, gjb@, mmoll@, op@ and lev@, who also participated in
testing.
Reviewed by: adrian
Sponsored by: Netflix
Sponsored by: Nginx, Inc.
* 286410
* 286413
* 286416
The initial commit broke a variety of debug and features that aren't
in the GENERIC kernels but are enabled in other platforms.
with the net80211 stack.
Historical background: originally wireless devices created an interface,
just like Ethernet devices do. Name of an interface matched the name of
the driver that created. Later, wlan(4) layer was introduced, and the
wlanX interfaces become the actual interface, leaving original ones as
"a parent interface" of wlanX. Kernelwise, the KPI between net80211 layer
and a driver became a mix of methods that pass a pointer to struct ifnet
as identifier and methods that pass pointer to struct ieee80211com. From
user point of view, the parent interface just hangs on in the ifconfig
list, and user can't do anything useful with it.
Now, the struct ifnet goes away. The struct ieee80211com is the only
KPI between a device driver and net80211. Details:
- The struct ieee80211com is embedded into drivers softc.
- Packets are sent via new ic_transmit method, which is very much like
the previous if_transmit.
- Bringing parent up/down is done via new ic_parent method, which notifies
driver about any changes: number of wlan(4) interfaces, number of them
in promisc or allmulti state.
- Device specific ioctls (if any) are received on new ic_ioctl method.
- Packets/errors accounting are done by the stack. In certain cases, when
driver experiences errors and can not attribute them to any specific
interface, driver updates ic_oerrors or ic_ierrors counters.
Details on interface configuration with new world order:
- A sequence of commands needed to bring up wireless DOESN"T change.
- /etc/rc.conf parameters DON'T change.
- List of devices that can be used to create wlan(4) interfaces is
now provided by net.wlan.devices sysctl.
Most drivers in this change were converted by me, except of wpi(4),
that was done by Andriy Voskoboinyk. Big thanks to Kevin Lo for testing
changes to at least 8 drivers. Thanks to Olivier Cochard, gjb@, mmoll@,
op@ and lev@, who also participated in testing. Details here:
https://wiki.freebsd.org/projects/ifnet/net80211
Still, drivers: ndis, wtap, mwl, ipw, bwn, wi, upgt, uath were not
tested. Changes to mwl, ipw, bwn, wi, upgt are trivial and chances
of problems are low. The wtap wasn't compilable even before this change.
But the ndis driver is complex, and it is likely to be broken with this
commit. Help with testing and debugging it is appreciated.
Differential Revision: D2655, D2740
Sponsored by: Nginx, Inc.
Sponsored by: Netflix
In order for drivers to provide an alternate set of scan methods,
these have to finally use an indirection table and all of the calls
in ieee80211_scan.c need to use said table.
For all existing drivers - this is basically a glorified, KBI-breaking
functional no-op.
This is also not the final form - too much functionality is currently
hiding in ieee80211_scan_sw.c that should be in ieee80211_scan.c.
That'll be the target of some follow-up commits.
Note:
* You have to recompile your kernel/drivers after this - the net80211 KBI has
changed.
* I'm not yet planning on bumping any versioning - I have a few more things
to shuffle around.
Tested:
* urtwn(4) - STA mode
* Intel 7260 in local repo - overriding the methods and table at
attach time has the desired effect (ie, all the methods are called,
but nothing is ever performed.)
Smart NICs with firmware (eg wpi, iwn, the new atheros parts, the intel 7260
series, etc) support doing a lot of things in firmware. This includes but
isn't limited to things like scanning, sending probe requests and receiving
probe responses. However, net80211 doesn't know about any of this - it still
drives the whole scan/probe infrastructure itself.
In order to move towards suppoting smart NICs, the receive path needs to
know about the channel/details for each received packet. In at least
the iwn and 7260 firmware (and I believe wpi, but I haven't tried it yet)
it will do the scanning, power-save and off-channel buffering for you -
all you need to do is handle receiving beacons and probe responses on
channels that aren't what you're currently on. However the whole receive
path is peppered with ic->ic_curchan and manual scan/powersave handling.
The beacon parsing code also checks ic->ic_curchan to determine if the
received beacon is on the correct channel or not.[1]
So:
* add freq/ieee values to ieee80211_rx_stats;
* change ieee80211_parse_beacon() to accept the 'current' channel
as an argument;
* modify the iv_input() and iv_recv_mgmt() methods to include the rx_stats;
* add a new method - ieee80211_lookup_channel_rxstats() - that looks up
a channel based on the contents of ieee80211_rx_stats;
* if it exists, use it in the mgmt path to switch the current channel
(which still defaults to ic->ic_curchan) over to something determined
by rx_stats.
This is enough to kick-start scan offload support in the Intel 7260
driver that Rui/I are working on. It also is a good start for scan
offload support for a handful of existing NICs (wpi, iwn, some USB
parts) and it'll very likely dramatically improve stability/performance
there. It's not the whole thing - notably, we don't need to do powersave,
we should not scan all channels, and we should leave probe request sending
to the firmware and not do it ourselves. But, this allows for continued
development on the above features whilst actually having a somewhat
working NIC.
TODO:
* Finish tidying up how the net80211 input path works.
Right now ieee80211_input / ieee80211_input_all act as the top-level
that everything feeds into; it should change so the MIMO input routines
are those and the legacy routines are phased out.
* The band selection should be done by the driver, not by the net80211
layer.
* ieee80211_lookup_channel_rxstats() only determines 11b or 11g channels
for now - this is enough for scanning, but not 100% true in all cases.
If we ever need to handle off-channel scan support for things like
static-40MHz or static-80MHz, or turbo-G, or half/quarter rates,
then we should extend this.
[1] This is a side effect of frequency-hopping and CCK modes - you
can receive beacons when you think you're on a different channel.
In particular, CCK (which is used by the low 11b rates, eg beacons!)
is decodable from adjacent channels - just at a low SNR.
FH is a side effect of having the hardware/firmware do the frequency
hopping - it may pick up beacons transmitted from other FH networks
that are in a different phase of hopping frequencies.
the given node.
This takes into account the per-node cap, the ic cap and the
per-channel regulatory caps.
This is designed to replace references to ni_txpower in various net80211
drivers - ni_txpower doesn't necessarily reflect the actual cap for
the given node (eg if the node has the default value of 50dBm (100) and
the administrator has manually configured a lower TX power.)
This patchset implements a new TX lock, covering both the per-VAP (and
thus per-node) TX locking and the serialisation through to the underlying
physical device.
This implements the hard requirement that frames to the underlying physical
device are scheduled to the underlying device in the same order that they
are processed at the VAP layer. This includes adding extra encapsulation
state (such as sequence numbers and CCMP IV numbers.) Any order mismatch
here will result in dropped packets at the receiver.
There are multiple transmit contexts from the upper protocol layers as well
as the "raw" interface via the management and BPF transmit paths.
All of these need to be correctly serialised or bad behaviour will result
under load.
The specifics:
* add a new TX IC lock - it will eventually just be used for serialisation
to the underlying physical device but for now it's used for both the
VAP encapsulation/serialisation and the physical device dispatch.
This lock is specifically non-recursive.
* Methodize the parent transmit, vap transmit and ic_raw_xmit function
pointers; use lock assertions in the parent/vap transmit routines.
* Add a lock assertion in ieee80211_encap() - the TX lock must be held
here to guarantee sensible behaviour.
* Refactor out the packet sending code from ieee80211_start() - now
ieee80211_start() is just a loop over the ifnet queue and it dispatches
each VAP packet send through ieee80211_start_pkt().
Yes, I will likely rename ieee80211_start_pkt() to something that
better reflects its status as a VAP packet transmit path. More on
that later.
* Add locking around the management and BAR TX sending - to ensure that
encapsulation and TX are done hand-in-hand.
* Add locking in the mesh code - again, to ensure that encapsulation
and mesh transmit are done hand-in-hand.
* Add locking around the power save queue and ageq handling, when
dispatching to the parent interface.
* Add locking around the WDS handoff.
* Add a note in the mesh dispatch code that the TX path needs to be
re-thought-out - right now it's doing a direct parent device transmit
rather than going via the vap layer. It may "work", but it's likely
incorrect (as it bypasses any possible per-node power save and
aggregation handling.)
Why not a per-VAP or per-node lock?
Because in order to ensure per-VAP ordering, we'd have to hold the
VAP lock across parent->if_transmit(). There are a few problems
with this:
* There's some state being setup during each driver transmit - specifically,
the encryption encap / CCMP IV setup. That should eventually be dragged
back into the encapsulation phase but for now it lives in the driver TX path.
This should be locked.
* Two drivers (ath, iwn) re-use the node->ni_txseqs array in order to
allocate sequence numbers when doing transmit aggregation. This should
also be locked.
* Drivers may have multiple frames queued already - so when one calls
if_transmit(), it may end up dispatching multiple frames for different
VAPs/nodes, each needing a different lock when handling that particular
end destination.
So to be "correct" locking-wise, we'd end up needing to grab a VAP or
node lock inside the driver TX path when setting up crypto / AMPDU sequence
numbers, and we may already _have_ a TX lock held - mostly for the same
destination vap/node, but sometimes it'll be for others. That could lead
to LORs and thus deadlocks.
So for now, I'm sticking with an IC TX lock. It has the advantage of
papering over the above and it also has the added advantage that I can
assert that it's being held when doing a parent device transmit.
I'll look at splitting the locks out a bit more later on.
General outstanding net80211 TX path issues / TODO:
* Look into separating out the VAP serialisation and the IC handoff.
It's going to be tricky as parent->if_transmit() doesn't give me the
opportunity to split queuing from driver dispatch. See above.
* Work with monthadar to fix up the mesh transmit path so it doesn't go via
the parent interface when retransmitting frames.
* Push the encryption handling back into the driver, if it's at all
architectually sane to do so. I know it's possible - it's what mac80211
in Linux does.
* Make ieee80211_raw_xmit() queue a frame into VAP or parent queue rather
than doing a short-cut direct into the driver. There are QoS issues
here - you do want your management frames to be encapsulated and pushed
onto the stack sooner than the (large, bursty) amount of data frames
that are queued. But there has to be a saner way to do this.
* Fragments are still broken - drivers need to be upgraded to an if_transmit()
implementation and then fragmentation handling needs to be properly fixed.
Tested:
* STA - AR5416, AR9280, Intel 5300 abgn wifi
* Hostap - AR5416, AR9160, AR9280
* Mesh - some testing by monthadar@, more to come.
This turns ieee80211_node_pwrsave(), ieee80211_sta_pwrsave() and
ieee80211_recv_pspoll() into methods.
The intent is to let drivers override these and tie into the power save
management pathway.
For ath(4), this is the beginning of forcing a node software queue to
stop and start as needed, as well as supporting "leaking" single frames
from the software queue to the hardware.
Right now, ieee80211_recv_pspoll() will attempt to transmit a single frame
to the hardware (whether it be a data frame on the power-save queue or
a NULL data frame) but the driver may have hardware/software queued frames
queued up. This initial work is an attempt at providing the hooks required
to implement correct behaviour.
Allowing ieee80211_node_pwrsave() to be overridden allows the ath(4)
driver to pause and unpause the entire software queue for a given node.
It doesn't make sense to transmit anything whilst the node is asleep.
Please note that there are other corner cases to correctly handle -
specifically, setting the MORE data bit correctly on frames to a station,
as well as keeping the TIM updated. Those particular issues can be
addressed later.
