Re: [PATCH RFC] soc: fujitsu: Add cache driver code

[Will Deacon <will@kernel.org>]

On Thu, Mar 04, 2021 at 10:34:43AM +0000, tan.shaopeng@fujitsu.com wrote:
> > On Wed, Mar 3, 2021 at 10:38 AM tan.shaopeng
> > <tan.shaopeng@jp.fujitsu.com> wrote:
> > > +
> > > +config FUJITSU_CACHE
> > > +        tristate "FUJITSU Cache Driver"
> > > +        depends on ARM64_VHE || COMPILE_TEST
> > > +        help
> > > +          FUJITSU Cache Driver
> > > +
> > > +          This driver offers cache functions for A64FX system.
> > > +         Loading this cache driver, control registers will be set to enable
> > > +         these functions, and advanced settings registers will be set by
> > default
> > > +         values. After loading this driver, you can use the default values of
> > the
> > > +         advanced settings registers or set the advanced settings registers
> > > +         from EL0. Unloading this driver, control registers will be clear to
> > > +         disable these functions.
> > > +          When built as a module, this will be called as "fujitsu_cache".
> > 
> > My feeling is that this code should be in arch/arm64/, as the cache
> > is generally considered part of the CPU, rather than part of the wider
> > SoC design, or something that can be controlled separately from the
> > core kernel and memory management code.
> 
> Thanks for your advice. I also would like to hear the opinions from 
> other soc&arm maintainers, and then consider whether to add this to 
> arch/arm64/.

Given that all of this is outside of the scope of the architecture, I don't
think that arch/arm64/ is the right place for it. Perhaps this would fit
into the resctrl rework that James has been doing for MPAM?

Will