siox: Make remove callback return void

The driver core ignores the return value of the remove callback, so
don't give siox drivers the chance to provide a value.

All siox drivers only allocate devm-managed resources in
.probe, so there is no .remove callback to fix.

Tested-by: Thorsten Scherer <t.scherer@eckelmann.de>
Acked-by: Thorsten Scherer <t.scherer@eckelmann.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20201125093106.240643-3-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

siox: Add helper macro to simplify driver registration

Add more helper macros for trivial driver init cases, similar to the
already existing module_platform_driver() or module_i2c_driver().

This helps to reduce driver init boilerplate.

Signed-off-by: Enrico Weigelt <info@metux.net>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

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>

siox: new driver framework for eckelmann SIOX

SIOX is a bus system invented at Eckelmann AG to control their building
management and refrigeration systems. Traditionally the bus was
implemented on custom microcontrollers, today Linux based machines are
in use, too.

The topology on a SIOX bus looks as follows:

,------->--DCLK-->---------------+----------------------.
^ v v
,--------. ,----------------------. ,------
| | | ,--------------. | |
| |--->--DOUT-->---|->-|shift register|->-|--->---|
| | | `--------------' | |
| master | | device | | device
| | | ,--------------. | |
| |---<--DIN---<---|-<-|shift register|-<-|---<---|
| | | `--------------' | |
`--------' `----------------------' `------
v ^ ^
`----------DLD-------------------+----------------------'

There are two control lines (DCLK and DLD) driven from the bus master to
all devices in parallel and two daisy chained data lines, one for input
and one for output. DCLK is the clock to shift both chains by a single
bit. On an edge of DLD the devices latch both their input and output
shift registers.

This patch adds a framework for this bus type.

Acked-by: Gavin Schenk <g.schenk@eckelmann.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>