rtw89: add Realtek 802.11ax driver

This driver named rtw89, which is the next generation of rtw88, supports
Realtek 8852AE 802.11ax 2x2 chip whose new features are OFDMA, DBCC,
Spatial reuse, TWT and BSS coloring; now some of them aren't implemented
though.

The chip architecture is entirely different from the chips supported by
rtw88 like RTL8822CE 802.11ac chip. First of all, register address ranges
are totally redefined, so it's impossible to reuse register definition. To
communicate with firmware, new H2C/C2H format is proposed. In order to have
better utilization, TX DMA flow is changed to two stages DMA. To provide
rich RX status information, additional RX PPDU packets are added.

Since there are so many differences mentioned above, we decide to propose
a new driver. It has many authors, they are listed in alphabetic order:

Chin-Yen Lee <timlee@realtek.com>
Ping-Ke Shih <pkshih@realtek.com>
Po Hao Huang <phhuang@realtek.com>
Tzu-En Huang <tehuang@realtek.com>
Vincent Fann <vincent_fann@realtek.com>
Yan-Hsuan Chuang <tony0620emma@gmail.com>
Zong-Zhe Yang <kevin_yang@realtek.com>

Tested-by: Aaron Ma <aaron.ma@canonical.com>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211008035627.19463-1-pkshih@realtek.com

treewide: replace '---help---' in Kconfig files with 'help'

Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over
'---help---'"), the number of '---help---' has been gradually
decreasing, but there are still more than 2400 instances.

This commit finishes the conversion. While I touched the lines,
I also fixed the indentation.

There are a variety of indentation styles found.

a) 4 spaces + '---help---'
b) 7 spaces + '---help---'
c) 8 spaces + '---help---'
d) 1 space + 1 tab + '---help---'
e) 1 tab + '---help---' (correct indentation)
f) 1 tab + 1 space + '---help---'
g) 1 tab + 2 spaces + '---help---'

In order to convert all of them to 1 tab + 'help', I ran the
following commend:

$ find . -name 'Kconfig*' | xargs sed -i 's/^[[:space:]]*---help---/\thelp/'

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

treewide: Add SPDX license identifier - Makefile/Kconfig

Add SPDX license identifiers to all Make/Kconfig files which:

- Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

rtw88: new Realtek 802.11ac driver

This is a new mac80211 driver for Realtek 802.11ac wireless network chips.
rtw88 now supports RTL8822BE/RTL8822CE now, with basic station mode
functionalities. The firmware for both can be found at linux-firmware.

https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git
For RTL8822BE: rtw88/rtw8822b_fw.bin
For RTL8822CE: rtw88/rtw8822c_fw.bin

And for now, only PCI buses (RTL8xxxE) are supported. We will add support
for USB and SDIO in the future. The bus interface abstraction can be seen
in this driver such as hci.h. Most of the hardware setting are the same
except for some TRX path or probing setup should be separated.

Supported:

* Basic STA/AP/ADHOC mode, and TDLS (STA is well tested)

Missing feature:

* WOW/PNO
* USB & SDIO bus (such as RTL8xxxU/RTL8xxxS)
* BT coexistence (8822B/8822C are combo ICs)
* Multiple interfaces (for now single STA is better supported)
* Dynamic hardware calibrations (to improve/stabilize performance)

Potential problems:

* static calibration spends too much time, and it is painful for
driver to leave IDLE state. And slows down associate process.
But reload function are under development, will be added soon!
* TRX statictics misleading, as we are not reporting status correctly,
or say, not reporting for "every" packet.

The next patch set should have BT coexistence code since RTL8822B/C are
combo ICs, and the driver for BT can be found after Linux Kernel v4.20.
So it is better to add it first to make WiFi + BT work concurrently.

Although now rtw88 is simple but we are developing more features for it.
Even we want to add support for more chips such as RTL8821C/RTL8814B.

Finally, rtw88 has many authors, listed alphabetically:

Ping-Ke Shih <pkshih@realtek.com>
Tzu-En Huang <tehuang@realtek.com>
Yan-Hsuan Chuang <yhchuang@realtek.com>

Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

net/wireless: fix spaces and grammar copy/paste in vendor Kconfig help text

Lots of the wireless driver vendor Kconfig symol help text says
"questions about cards." (2 spaces between "about" and "cards")

Besides dropping one of those spaces, it also needs some other word
inserted there. Instead of putting each vendor's name there, I chose
to say "these" cards in all of the Kconfig help text.

Cc: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

realtek: create separate Kconfig file

Add new a Kconfig file and a vendor config for realtek. Also update MAINTAINERS
which we missed to do when earlier moving rtlwifi.

Signed-off-by: Kalle Valo <kvalo@codeaurora.org>