[PATCH v3 1/2] cache: Add StarFive StarLink cache management for StarFive JH8100

[Joshua Yeong]

Emil Renner Berthing wrote:
> Joshua Yeong wrote:
> >
> >
> > Emil Renner Berthing wrote:
> > > Joshua Yeong wrote:
> > > > Emil Renner Berthing wrote:
> > > > > Joshua Yeong wrote:
> > > > > > Add StarFive Starlink cache management driver for
> > > > > > JH8100 SoC. This driver enables RISC-V non-standard cache
> > > > > > operation on
> > > > > > JH8100 that does not support Zicbom extension instructions.
> > > > > >
> > > > > > Signed-off-by: Joshua Yeong <joshua.yeong at starfivetech.com>
> > > > > > ---
> > > > > >  drivers/cache/Kconfig                   |   9 ++
> > > > > >  drivers/cache/Makefile                  |   5 +-
> > > > > >  drivers/cache/starfive_starlink_cache.c | 135
> > > > > > ++++++++++++++++++++++++
> > > > > >  3 files changed, 147 insertions(+), 2 deletions(-)  create
> > > > > > mode
> > > > > > 100644 drivers/cache/starfive_starlink_cache.c
> > > > > >
> > > > > > diff --git a/drivers/cache/Kconfig b/drivers/cache/Kconfig
> > > > > > index
> > > > > > 9345ce4976d7..9181cd391f53 100644
> > > > > > --- a/drivers/cache/Kconfig
> > > > > > +++ b/drivers/cache/Kconfig
> > > > > > @@ -14,4 +14,13 @@ config SIFIVE_CCACHE
> > > > > >  	help
> > > > > >  	  Support for the composable cache controller on SiFive
> platforms.
> > > > > >
> > > > > > +config STARFIVE_STARLINK_CACHE
> > > > > > +	bool "StarFive StarLink Cache controller"
> > > > > > +	depends on RISCV
> > > > > > +	depends on ARCH_STARFIVE
> > > > > > +	select RISCV_DMA_NONCOHERENT
> > > > > > +	select RISCV_NONSTANDARD_CACHE_OPS
> > > > > > +	help
> > > > > > +	  Support for the StarLink cache controller on StarFive
> platforms.
> > > > >
> > > > > This is a bit misleading. The JH71x0s don't have this. It's only
> > > > > on the JH8100 so far, and hopefully later SoCs will just
> > > > > implement RISC-V
> > > standards for this.
> > > > > So maybe something like
> > > > >
> > > > > "Support for the StarLink cache controller on the StarFive JH8100 SoC."
> > > > >
> > > >
> > > > Hi Emil,
> > > >
> > > > The StarLink-500 cache controller is not designed exclusively for JH8100
> SoC.
> > > > While it is true that it currently exists on the StarFive
> > > > platform, CPU/SoC that does not come with Zicbom extensions
> > > > supported would need to rely on this cache drive to do cache
> > > > management operations. I think we don’t need to mentioned 'JH8100
> SoC' here.
> > >
> > > Wait, in the previous mail you said that future designs will
> > > implement Zicbom and not need this work-around, but here you're
> > > talking about other SoCs that do need it. So which is it?
> >
> > If you visit the company website and look for StarLink-500, you will
> > find that it is a standalone IP that the company is selling as an
> > interconnect. Anyone who integrates StarLink without Zicbom extensions
> > may utilize the cache management operation from this IP.
> 
> So then the "on StarFive platforms" part is wrong? Or will this always go
> together with the Dubhe cores?

It would be 'on StarFive platform' without 'JH8100 SoC' that you suggested.
StarFive's newer cores that will have Zicbom extensions supported. Those
CPU core will not need to have this cache controller enabled.
 
> 
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