This includes helper function for pin configuration
and a DT binding for the pinctrl DT node.
There's two important notes to be made regarding this
protocol:
* pinctrl drivers have no subsytem API to implement as opposed
to clock control drivers. Because of this (and the fact that
`pinctrl_configure_pins()` doesn't require a `struct device`
handle) the pinctrl driver consists only of a helper function,
which implements the `PINCTRL_CONFIGURE_PINS` command.
Additionally, the `scmi_protocol` structure is defined inside
the pinctrl helpers source file to avoid redundant code
(otherwise, each SCMI-based pinctrl driver would have to define
it its source file).
* each vendor may have their own set of pin propeties and DT
representations for them. Because of this, there can't be a
generic, SCMI-based pinctrl driver. As such, each vendor who
wants to use the SCMI support for pinctrl operations will have
to implement their pinctrl driver (which, to put it simply,
revolves around implemeting `pinctrl_configure_pins()`) and
make use of the pin configuration function introduced in this
commit. Moreover, this means that each vendor will have control
over the way their pin properties are encoded in the
`scmi_pinctrl_settings` structure.
Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>
6b689d0207