mux: mmio: drop obsolete dependency on COMPILE_TEST

Since commit 0166dc11be91 ("of: make CONFIG_OF user selectable"), it
is possible to test-build any driver which depends on OF on any
architecture by explicitly selecting OF. Therefore depending on
COMPILE_TEST as an alternative is no longer needed.

It is actually better to always build such drivers with OF enabled,
so that the test builds are closer to how each driver will actually be
built on its intended target. Building them without OF may not test
much as the compiler will optimize out potentially large parts of the
code. In the worst case, this could even pop false positive warnings.
Dropping COMPILE_TEST here improves the quality of our testing and
avoids wasting time on non-existent issues.

As a minor optimization, this also lets us drop of_match_ptr(), as we
now know what it will resolve to, we might as well save cpp some work.

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Peter Rosin <peda@axentia.se>
Link: https://lore.kernel.org/r/bc790b4e-1cb4-4ef5-3da8-9d0e6b613bc7@axentia.se
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: mmio: add generic regmap bitfield-based multiplexer

Generic register bitfield-based multiplexer that controls the multiplexer
producer defined under a parent node.
The driver corresponding to parent node provides register read/write
capabilities.

Signed-off-by: Pankaj Bansal <pankaj.bansal@nxp.com>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: adgs1408: new driver for Analog Devices ADGS1408/1409 mux

This patch adds basic support for Analog Device ADGS1408/09 SPI mux
controller.

The device is probed and set to a disabled state. It uses the new mux
controller framework.

Signed-off-by: Mircea Caprioru <mircea.caprioru@analog.com>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: add SPDX identifiers to all mux source files

Remove all free-text license texts.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text.

No copyright headers or other non-license-description text was removed.

Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: remove the Kconfig question for the subsystem

The MULTIPLEXER question in the Kconfig might be confusing and is
of dubious value. Remove it. This makes consumers responsible for
selecting MULTIPLEXER, which they already do.

Signed-off-by: Peter Rosin <peda@axentia.se>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: adg792a: always require I2C support

COMPILE_TEST makes no sense when I2C is disabled, as the driver cannot compile
in that configuration:

drivers/mux/mux-adg792a.c: In function 'adg792a_write_cmd':
drivers/mux/mux-adg792a.c:34:9: error: implicit declaration of function 'i2c_smbus_write_byte_data'; did you mean 'i2c_set_clientdata'? [-Werror=implicit-function-declaration]
drivers/mux/mux-adg792a.o: In function `adg792a_driver_init':
mux-adg792a.c:(.init.text+0x14): undefined reference to `i2c_register_driver'
drivers/mux/mux-adg792a.o: In function `adg792a_probe':
mux-adg792a.c:(.text.adg792a_probe+0x94): undefined reference to `i2c_smbus_write_byte_data'
drivers/mux/mux-adg792a.o: In function `adg792a_set':
mux-adg792a.c:(.text.adg792a_set+0x80): undefined reference to `i2c_smbus_write_byte_data'

Fixes: afda08c4caa9 ("mux: adg792a: add mux controller driver for ADG792A/G")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: mmio-based syscon mux controller

This adds a driver for mmio-based syscon multiplexers controlled by
bitfields in a syscon register range.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: adg792a: add mux controller driver for ADG792A/G

Analog Devices ADG792A/G is a triple 4:1 mux.

Reviewed-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: gpio: add mux controller driver for gpio based multiplexers

The driver builds a single multiplexer controller using a number
of gpio pins. For N pins, there will be 2^N possible multiplexer
states. The GPIO pins can be connected (by the hardware) to several
multiplexers, which in that case will be operated in parallel.

Reviewed-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

mux: minimal mux subsystem

Add a new minimalistic subsystem that handles multiplexer controllers.
When multiplexers are used in various places in the kernel, and the
same multiplexer controller can be used for several independent things,
there should be one place to implement support for said multiplexer
controller.

A single multiplexer controller can also be used to control several
parallel multiplexers, that are in turn used by different subsystems
in the kernel, leading to a need to coordinate multiplexer accesses.
The multiplexer subsystem handles this coordination.

Thanks go out to Lars-Peter Clausen, Jonathan Cameron, Rob Herring,
Wolfram Sang, Paul Gortmaker, Dan Carpenter, Colin Ian King, Greg
Kroah-Hartman and last but certainly not least to Philipp Zabel for
helpful comments, reviews, patches and general encouragement!

Reviewed-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Peter Rosin <peda@axentia.se>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Tested-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>