arm: remove zte zx platform left-over

Commit 89d4f98ae90d ("ARM: remove zte zx platform") missed to remove some
definitions for this platform's debug and serial, e.g., code dependent on
the config DEBUG_ZTE_ZX.

Fortunately, ./scripts/checkkconfigsymbols.py detects this and warns:

DEBUG_ZTE_ZX
Referencing files: arch/arm/include/debug/pl01x.S

Further review by Arnd Bergmann identified even more dead code in the
amba serial driver.

Remove all this left-over from the zte zx platform.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20211102063810.932-1-lukas.bulwahn@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ARM: 9004/1: debug: Split waituart to CTS and TXRDY

This patch was triggered by a remark from Russell that
introducing a call to the waituart (needed to fix debug prints
on the Qualcomm platforms) was dangerous because in some cases
this will involve waiting for a modem CTS (clear to send)
signal, and debug messages would maybe not work on platforms
with no modem connected to the UART port: they will just
hang waiting for the modem to assert CTS and this might never
happen.

Looking through all UART debug drivers implementing the waituart
macro I discovered that all users except two actually use this
macro to check if the UART is ready for TX, let's call this
TXRDY.

Only two debug UART drivers actually check for CTS:
- arch/arm/include/debug/8250.S
- arch/arm/include/debug/tegra.S

The former is very significant since the 8250 is possibly
the most common UART on the planet.

We have the following problem: the semantics of waituart are
ambiguous making it dangerous to introduce the macro to debug
code fixing debug prints for Qualcomm. To start to pry this
problem apart, this patch does the following:

- Convert all debug UART drivers to define two macros:

- waituartcts with the clear semantic to wait for CTS
to be asserted

- waituarttxrdy with the clear semantic to wait for the TX
capability of the UART to be ready

- When doing this take care to assign the right function to
each drivers macro, so they now do exactly the above.

- Update the three sites in the kernel invoking the waituart
macro to call waituartcts/waituarttxrdy in sequence, so that
the functional impact on the kernel should be zero.

After this we can start to change the code sites using this
code to do the right thing.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ARM: zx: add low level debug support for zx296702

Use the UART0 peripheral for low level debug. Only the UART port 0 is
currently supported.

Signed-off-by: Jun Nie <jun.nie@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

ARM: pl01x debug code endian fix

The PL01X debug code needs to take into account which endian mode the
processor is running in. If it is big-endian, ensure the data is swapped
appropriately.

Note, we could do this slightly more efficiently if we have an macro to
do the necessary swap for the bits used by test.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>

ARM: debug: move PL01X debug include into arch/arm/include/debug/

Now that the PL01X debug include can mostly stand alone without
requiring platforms to provide any macros, move it into the debug
directory so it can be directly included. This allows us to get rid of
a lot of debug-macros include files.

The autodetect case for Versatile Express and the ux500 are left alone;
these are more complicated implementations.

Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Ryan Mallon <rmallon@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>