[PATCH 3/5] arm: qemu: implement enable_caches()

[Tom Rini]

On Sat, Jun 06, 2020 at 10:50:59PM +0200, Heinrich Schuchardt wrote:
> On 6/6/20 7:15 PM, Ard Biesheuvel wrote:
> > Add an override for enable_caches to enable the I and D caches, along
> > with the cached 1:1 mapping of all of DRAM. This is needed for running
> > U-Boot under virtualization with QEMU/kvm.
> >
> > Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
> > ---
> >  board/emulation/qemu-arm/qemu-arm.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/board/emulation/qemu-arm/qemu-arm.c b/board/emulation/qemu-arm/qemu-arm.c
> > index 69e8ef46f1f5..1b0d543b93c1 100644
> > --- a/board/emulation/qemu-arm/qemu-arm.c
> > +++ b/board/emulation/qemu-arm/qemu-arm.c
> > @@ -4,6 +4,7 @@
> >   */
> >
> >  #include <common.h>
> > +#include <cpu_func.h>
> >  #include <dm.h>
> >  #include <fdtdec.h>
> >  #include <init.h>
> > @@ -94,6 +95,12 @@ void *board_fdt_blob_setup(void)
> >  	return (void *)CONFIG_SYS_SDRAM_BASE;
> >  }
> >
> > +void enable_caches(void)
> > +{
> > +	 icache_enable();
> > +	 dcache_enable();
> > +}
> > +
> 
> For other ARM architectures I have seen:
> 
> int arch_cpu_init(void)
> {
>         icache_enable();
>         return 0;
> }
> 
> void enable_caches(void)
> {
>         dcache_enable();
> }
> 
> Some boards have
> 
> if (!icache_status())
> 	icache_enable();
> 
> others
> 
> #if !CONFIG_IS_ENABLED(SYS_ICACHE_OFF)
> 	icache_enable();
> #endif
> 
> Tom could you, please, advice what is the correct way to do it.

Off-hand?  Dealing with it per SoC/mach/board as we do today.  Sometimes
we need a dcache_disable() before the dcache_enable() as well to clear
out previous mappings.  So dropping this in here is probably the best
choice for qemu-arm.  Thanks!

-- 
Tom
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