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
