On Keystone SOCs, ARM host can send interrupts to DSP cores using the
DSP GPIO controller IP. Each DSP GPIO controller provides 28 IRQ signals for
each DSP core. This is one of the component used by the IPC mechanism used
on Keystone SOCs.

Keystone 2 DSP GPIO controller has specific features:
- each GPIO can be configured only as output pin;
- setting GPIO value to 1 causes IRQ generation on target DSP core;
- reading pin value returns 0 - if IRQ was handled or 1 - IRQ is still
  pending.

This patch updates gpio-syscon driver to be reused by Keystone 2 SoCs,
because the Keystone 2 DSP GPIO controller is controlled through Syscon
devices and, as requested by Linus Walleij, such kind of GPIO controllers
should be integrated with drivers/gpio/gpio-syscon.c driver.
Signed-off-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

This patch adds handling of new "gpio,syscon-dev" DT property,
which allows to specify syscon node and data/direction registers
offsets in DT.

"gpio,syscon-dev" has following format:
	gpio,syscon-dev = <&syscon_dev data_reg_offset [direction_reg_offset]>;

where
 - syscon_dev - phandle on syscon node
 - data_reg_offset - offset of data register (in bytes)
 - direction_reg_offset - offset of dirrection register (optional, in bytes)

for example:
	gpio,syscon-dev = <&devctrl 0x254>;

In such way, the support of multiple Syscon GPIO devices is added.
Signed-off-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Some SoCs (like Keystone) may require to perform special
sequence of operations to assign output GPIO value, so default
implementation of .set() callback from gpio-syscon driver
can't be used.

Hence, add optional, SoC specific callback to assign output
gpio value.
Signed-off-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Signed-off-by: Nabdoulaye berthe <berthe.ab@gmail.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

SYSCON driver was designed for using memory areas (registers)
that are used in several subsystems. There are systems (CPUs)
which use bits in one register for various purposes and thus
should be handled by various kernel subsystems. This driver
allows you to use the individual SYSCON bits as GPIOs.
ARM CLPS711X SYSFLG1 input lines has been added as first user
of this driver.
Signed-off-by: NAlexander Shiyan <shc_work@mail.ru>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>