[PATCH 5/6] gpio: Add new gpio-macsmc driver for Apple Macs

[Linus Walleij]

On Thu, Sep 1, 2022 at 3:54 PM Russell King <rmk+kernel at armlinux.org.uk> wrote:

> From: Hector Martin <marcan at marcan.st>
>
> This driver implements the GPIO service on top of the SMC framework
> on Apple Mac machines. In particular, these are the GPIOs present in the
> PMU IC which are used to control power to certain on-board devices.
>
> Although the underlying hardware supports various pin config settings
> (input/output, open drain, etc.), this driver does not implement that
> functionality and leaves it up to the firmware to configure things
> properly. We also don't yet support interrupts/events. This is
> sufficient for device power control, which is the only thing we need to
> support at this point. More features will be implemented when needed.
>
> To our knowledge, only Apple Silicon Macs implement this SMC feature.
>
> Signed-off-by: Hector Martin <marcan at marcan.st>
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>

Overall this looks very good provided the SMC API is fine
with the platform/MFD maintainers, I like the usage of .init_valid_mask
which is used just as intended. Andy's detailed review points
should be addressed reasonably after that it's:
Reviewed-by: Linus Walleij <linus.walleij at linaro.org>

Yours,
Linus Walleij