[RFC v2 01/39] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Maciej W. Rozycki]

On Fri, 29 Apr 2022, Niklas Schnelle wrote:

> We introduce a new HAS_IOPORT Kconfig option to indicate support for
> I/O Port access. In a future patch HAS_IOPORT=n will disable compilation
> of the I/O accessor functions inb()/outb() and friends on architectures
> which can not meaningfully support legacy I/O spaces such as s390 or
> where such support is optional. The "depends on" relations on HAS_IOPORT
> in drivers as well as ifdefs for HAS_IOPORT specific sections will be
> added in subsequent patches on a per subsystem basis.
[...]
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index de3b32a507d2..4c55df08d6f1 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -47,6 +47,7 @@ config MIPS
>  	select GENERIC_SMP_IDLE_THREAD
>  	select GENERIC_TIME_VSYSCALL
>  	select GUP_GET_PTE_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
> +	select HAS_IOPORT
>  	select HAVE_ARCH_COMPILER_H
>  	select HAVE_ARCH_JUMP_LABEL
>  	select HAVE_ARCH_KGDB if MIPS_FP_SUPPORT

 NAK, not all MIPS systems have the port I/O space, and we have it already 
handled via the NO_IOPORT_MAP option.  We'll need to have HAS_IOPORT set 
to !NO_IOPORT_MAP (or vice versa) for the MIPS architecture.

  Maciej