IQ calibration is used to calibrate RF characteristic to yield expected
performance. Basically, we do calibration twice and compare the similarity
to determine calibration is good or not, if not we do the third
calibration, and then compare with the results of first and second
calibration. If it still not similar, IQK is failed.

Before doing calibration, we need to backup registers that will be
modified in calibration procedure, and restore these registers after
calibration is done.

A calibration procedure can divided into four sub-procedures that are
S1-TX, S1-RX, S0-TX and S0-RX. Where, S1 and S0 represent to path A and B
respectively. Each sub-procedure configure proper registers, and then
rigger one-shot calibration and poll until completion. For RX calibration,
it needs to do twice one-shot calibration, first one is to yield parameter
used by second one.

The result of TX part is stored for TX power tracking that adjusts TX AGC
to output expected power.
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200512102621.5148-3-yhchuang@realtek.com