ath9k: fix and simplify FFT max index retrieval

FFT max index retrieval was not retrieved correctly for HT20/HT40 FFT
frames. Fixing the retrieval allows us to remove the fixup function as
well. While at it, split the spectral_max_index function into versions
for ht20 and ht40 to simplify the code.

Cc: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

ath9k: move spectral scan support under a separate config symbol

At the moment, spectral scan support, and with it RELAY, is always enabled
with ATH9K[_HTC]_DEBUGFS. Spectral scan support is currently the only user
of RELAY in ath9k, and it unconditionally reserves a relay channel.

Having debugfs support in ath9k is often useful even on very small embedded
routers, where we'd rather like to avoid the code size and RAM usage of the
relay support.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

ath9k: move RELAY and DEBUG_FS to ATH9K[_HTC]_DEBUGFS

Currently, the common ath9k_common module needs to have a
dependency on RELAY and DEBUG_FS in order to built. This
is usually not a problem. But for RAM and FLASH starved
AR71XX devices, every little bit counts.

This patch adds a new symbol CONFIG_ATH9K_COMMON_DEBUG
which makes it possible to drop the RELAY and DEBUG_FS
dependency there and move it to ATH_(HTC)_DEBUGFS.

Note: The shared FFT/spectral code (which is the only user
of the relayfs in ath9k*) needs DEBUG_FS to export the relayfs
interface to dump the data to userspace. So it makes no sense
to have the functions compiled in, if DEBUG_FS is not there.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>

ath9k: Move processing of FFT frames to different functions

Since more checks and fixes will be added later and ath_cmn_process_fft is
already big enough.

Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

ath9k: Fix hanlding of maximum magnitude index

Maximum magnitude index is a 5bit signed integer,
convert to an 8bit signed integer and then "shift" it so that it can be used
as an array index. Note that the current implementation adds +1 to the index
value (so it can't be used as an array index) and it's only valid for HT20
channels.

Note that the maximum magnitude index is not being used by
the userspace tools that parse FFT samples (they just use
maximum magnitude) so this doesn't break userspace compatibility.

Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

ath9k: common-spectral: don't depend from ATH9K_DEBUGFS

we can have here two variants. Add
ATH9K_CMN_DEBUGFS y if ATH9K_CMN_DEBUGFS || ATH9K_HTC_DEBUGFS
wich will add more configurations and testcases. Or remove ATH9K_HTC_DEBUGFS
which need more time to be done.

So, make common-spectral ignore ATH9K_DEBUGFS option for now.

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

ath9k: move spectral.* to common-spectral.*

and rename exports from ath9k_spectral_* to ath9k_cmn_spectral_*

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>