On Wed, Jan 22, 2014 at 11:20:55AM +0000, Will Deacon wrote:
> > +#ifdef CONFIG_CPU_CP15
> > +/* Macro for setting/clearing bits in sctlr */
> > + .macro update_sctlr, set:req, clear:req, tmp:req, tmp2:req
> > + mrc p15, 0, \tmp, c1, c0, 0
> > + ldr \tmp2, =\set
> > + orr \tmp, \tmp, \tmp2
> > + ldr \tmp2, =\clear
> > + mvn \tmp2, \tmp2
> > + and \tmp, \tmp, \tmp2
> > + mcr p15, 0, \tmp, c1, c0, 0
>
> I think this would be cleaner if you force the caller to put set and clear
> into registers beforehand, rather than have to do the literal load every
> time. Also, I don't think set and clear should be required (and then you can
> lose tmp2 as well).
I can't figure out how to make register-parameters non-required
(i.e. conditionalise on whether an optional parameter was provided),
so my attempt of refactoring actually ends up using an additional
register:
#ifdef CONFIG_CPU_CP15
/* Macro for setting/clearing bits in sctlr */
.macro update_sctlr, set:req, clear:req, tmp:req
mrc p15, 0, \tmp, c1, c0, 0
orr \tmp, \set
mvn \clear, \clear
and \tmp, \tmp, \clear
mcr p15, 0, \tmp, c1, c0, 0
.endm
#endif
If you think that's an improvement I can do that, and I have (just)
enough registers to spare.
If I'm being daft with my macro issues, do point it out.
/
Leif
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