sys: Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

sys/dev: further adoption of SPDX licensing ID tags.

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.

[ath] commit initial bluetooth coexistence support for the MCI NICs.

This is the initial framework to call into the MCI HAL routines and drive
the basic state engine.

The MCI bluetooth coex model uses a command channel between wlan and
bluetooth, rather than a 2-wire or 3-wire signaling protocol to control things.
This means the wlan and bluetooth chip exchange a lot more information and
signaling, even at the per-packet level. The NICs in question can share
the input LNA and output PA on the die, so they absolutely can't stomp
on each other in a silly fashion. It also allows for the bluetooth side
to signal when profiles come and go, so the driver can take appropriate
control. There's also the possibility of dynamic bluetooth/wlan duty cycle
control which I haven't yet really played with.

It configures things up with a static "wlan wins everything" coexistence,
configures up the available 2GHz channel map for bluetooth, sets a static
duty cycle for bluetooth/wifi traffic priority and drives the basics needed to
keep the MCI HAL code happy.

It doesn't do any actual coexistence except to default to "wlan wins everything",
which at least demonstrates that things do indeed work. Bluetooth inquiry frames
still trump wifi (including beacons), so that demonstrates things really do
indeed seem to work.

Tested:

* AR9462 (WB222), STA mode + bt
* QCA9565 (WB335), STA mode + bt

TODO:

* .. the rest of coexistence. yes, bluetooth, not people. That stuff's hard.
* It doesn't do the initial BT side calibration, which requires a WLAN chip
reset. I'll fix up the reset path a bit more first before I enable that.
* The 1-ant and 2-ant configuration bits aren't being set correctly in
if_ath_btcoex.c - I'll dig into that and fix it in a subsequent commit.
* It's not enabled by default for WB222/WB225 even though I believe it now
can be - I'll chase that up in a subsequent commit.

Obtained from: Qualcomm Atheros, Linux ath9k

Bring over the initial static bluetooth coexistence configuration
for the WB195 combo NIC - an AR9285 w/ an AR3011 USB bluetooth NIC.

The AR3011 is wired up using a 3-wire coexistence scheme to the AR9285.

The code in if_ath_btcoex.c sets up the initial hardware mapping
and coexistence configuration. There's nothing special about it -
it's static; it doesn't try to configure bluetooth / MAC traffic priorities
or try to figure out what's actually going on. It's enough to stop basic
bluetooth traffic from causing traffic stalls and diassociation from
the wireless network.

To use this code, you must have the above NIC. No, it won't work
for the AR9287+AR3012, nor the AR9485, AR9462 or AR955x combo cards.

Then you set a kernel hint before boot or before kldload, where 'X'
is the unit number of your AR9285 NIC:

# kenv hint.ath.X.btcoex_profile=wb195

This will then appear in your boot messages:

[100482] athX: Enabling WB195 BTCOEX

This code is going to evolve pretty quickly (well, depending upon my
spare time) so don't assume the btcoex API is going to stay stable.

In order to use the bluetooth side, you must also load in firmware using
ath3kfw and the binary firmware file (ath3k-1.fw in my case.)

Tested:

* AR9280, no interference
* WB195 - AR9285 + AR3011 combo; STA mode; basic bluetooth inquiries
were enough to cause traffic stalls and disassociations. This has
stopped with the btcoex profile code.

TODO:

* Importantly - the AR9285 needs ASPM disabled if bluetooth coexistence
is enabled. No, I don't know why. It's likely some kind of bug to do
with the AR3011 sending bluetooth coexistence signals whilst the device
is asleep. Since we don't actually sleep the MAC just yet, it shouldn't
be a problem. That said, to be totally correct:

+ ASPM should be disabled - upon attach and wakeup
+ The PCIe powersave HAL code should never be called

Look at what the ath9k driver does for inspiration.

* Add WB197 (AR9287+AR3012) support
* Add support for the AR9485, which is another combo like the AR9285
* The later NICs have a different signaling mechanism between the MAC
and the bluetooth device; I haven't even begun to experiment with
making that HAL code work. But it should be a lot more automatic.

* The hardware can do much more interesting traffic weighting with
bluetooth and wifi traffic. None of this is currently used.
Ideally someone would code up something to watch the bluetooth traffic
GPIO (via an interrupt) and then watch it go high/low; then figure out
what the bluetooth traffic is and adjust things appropriately.

* If I get the time I may add in some code to at least track this stuff
and expose statistics. But it's up to someone else to experiment with
the bluetooth coexistence support and add the interesting stuff (like
"real" detection of bulk, audio, etc bluetooth traffic patterns and
change wifi parameters appropriately - eg, maximum aggregate length,
transmit power, using quiet time to control TX duty cycle, etc.)