[PATCH v2 01/13] arm64: kernel: add MPIDR_EL1 accessors macros

[Lorenzo Pieralisi]

On Tue, Oct 15, 2013 at 11:11:30AM +0100, Will Deacon wrote:
> On Mon, Oct 14, 2013 at 12:02:58PM +0100, Lorenzo Pieralisi wrote:
> > In order to simplify access to different affinity levels within the
> > MPIDR_EL1 register values, this patch implements some preprocessor
> > macros that allow to retrieve the MPIDR_EL1 affinity level value according
> > to the level passed as input parameter.
> > 
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> > ---
> >  arch/arm64/include/asm/cputype.h | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
> > index 5fe138e..2c9e295 100644
> > --- a/arch/arm64/include/asm/cputype.h
> > +++ b/arch/arm64/include/asm/cputype.h
> > @@ -30,6 +30,16 @@
> >  
> >  #define MPIDR_HWID_BITMASK	0xff00ffffff
> >  
> > +#define MPIDR_LEVEL_BITS 8
> > +#define MPIDR_LEVEL_MASK ((1 << MPIDR_LEVEL_BITS) - 1)
> > +
> > +#define MPIDR_LEVEL_SHIFT(level) ({					\
> > +	(level == 3) ? 32 : MPIDR_LEVEL_BITS * level;			\
> 
> You can avoid the check if you do:
> 
>   ((1 << level) >> 1) << 3)
> 
> where that '3' is log2 MPIDR_LEVEL_BITS, so you could factor that out and
> redefine MPIDR_LEVEL_BITS in terms of a shift.

Yes, that's ways neater, thank you.

Lorenzo