[PATCH 04/14] mfd: arizona: Allow building arizona MFD-core as module

[Charles Keepax]

On Sun, Dec 27, 2020 at 10:12:22PM +0100, Hans de Goede wrote:
> There is no reason why the arizona core,irq and codec model specific
> regmap bits cannot be build as a module. All they do is export symbols
> which are used by the arizona-spi and/or arizona-i2c modules, which
> themselves can be built as module.
> 
> Change the Kconfig and Makefile arizona bits so that the arizona MFD-core
> can be built as a module.
> 
> This is especially useful on x86 platforms with a WM5102 codec, this
> allows the arizona MFD driver necessary for the WM5102 codec to be
> enabled in generic distro-kernels without growing the base kernel-image
> size.
> 
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> ---

I think this patch might still cause some issues. ASoC has an
idiom where the machine driver does a select on the necessary
CODEC drivers. Select doesn't take care of dependencies etc. So I
believe if you build the machine driver as built in, it then
selects the CODEC as built in. If you have the MFD as a module
the build then fails due to the the CODEC calling some Arizona
functions.

arizona_request_irq, arizona_free_irq, arizona_set_irq_wake

On Madera we made the equivalents inline functions to avoid the
issue, the same should work here.

include/linux/irqchip/irq-madera.h

Thanks,
Charles