[PATCH 3/8] arm: apple: Add RTKit support

[Mark Kettenis]

> From: Simon Glass <sjg at chromium.org>
> Date: Fri, 21 Jan 2022 18:40:14 -0700
> 
> Hi Mark,
> 
> On Fri, 14 Jan 2022 at 04:05, Mark Kettenis <kettenis at openbsd.org> wrote:
> >
> > Most Apple IOPs run a firmware that is based on what Apple calls
> > RTKit. RTKit implements a common mailbox protocol.  This code
> > provides an implementation of the AP side of this protocol,
> > providing a function to initialize RTKit-based firmwares as well
> > as a function to do a clean shutdown of this firmware.
> >
> > Signed-off-by: Mark Kettenis <kettenis at openbsd.org>
> > ---
> >  arch/arm/include/asm/arch-apple/rtkit.h |  11 ++
> >  arch/arm/mach-apple/Makefile            |   1 +
> >  arch/arm/mach-apple/rtkit.c             | 231 ++++++++++++++++++++++++
> >  3 files changed, 243 insertions(+)
> >  create mode 100644 arch/arm/include/asm/arch-apple/rtkit.h
> >  create mode 100644 arch/arm/mach-apple/rtkit.c
> 
> This should be a driver.

This isn't a driver but just a bit of helper code that implements the
RTKit protocol.  It will be used by the Apple NVMe driver and a future
SMC driver.  The same approach is being taken in Linux.  Since it is
intended to be shared, I didn't put it in the NVMe driver itself.