| Message ID | 20180514094640.27569-4-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, May 14, 2018 at 10:46:25AM +0100, Mark Rutland wrote: > Currently we have a couple of helpers to manipulate bits in particular > sysregs: > > * config_sctlr_el1(u32 clear, u32 set) > > * change_cpacr(u64 val, u64 mask) > > The parameters of these differ in naming convention, order, and size, > which is unfortunate. They also differ slightly in behaviour, as > change_cpacr() skips the sysreg write if the bits are unchanged, which > is a useful optimization when sysreg writes are expensive. > > Before we gain more yet another sysreg manipulation function, let's > unify these with a common helper, providing a consistent order for > clear/set operands, and the write skipping behaviour from > change_cpacr(). Code will be migrated to the new helper in subsequent > patches. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Dave Martin <dave.martin@arm.com> > Cc: Marc Zyngier <marc.zyngier@arm.com> Makes sense. I felt I was (re)inventing an idiom with change_cpacr() at the time, though it didn't quite seem worth factoring out. Now you plan to add a third similar manipulator, this factoring makes sense. Reviewed-by: Dave Martin <Dave.Martin@arm.com> > --- > arch/arm64/include/asm/sysreg.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h > index bd1d1194a5e7..b52762769329 100644 > --- a/arch/arm64/include/asm/sysreg.h > +++ b/arch/arm64/include/asm/sysreg.h > @@ -729,6 +729,17 @@ asm( > asm volatile("msr_s " __stringify(r) ", %x0" : : "rZ" (__val)); \ > } while (0) > > +/* > + * Modify bits in a sysreg. Bits in the clear mask are zeroed, then bits in the > + * set mask are set. Other bits are left as-is. > + */ > +#define sysreg_clear_set(sysreg, clear, set) do { \ > + u64 __scs_val = read_sysreg(sysreg); \ > + u64 __scs_new = (__scs_val & ~(u64)(clear)) | (set); \ > + if (__scs_new != __scs_val) \ > + write_sysreg(__scs_new, sysreg); \ > +} while (0) > + > static inline void config_sctlr_el1(u32 clear, u32 set) > { > u32 val; > -- > 2.11.0 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index bd1d1194a5e7..b52762769329 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -729,6 +729,17 @@ asm( asm volatile("msr_s " __stringify(r) ", %x0" : : "rZ" (__val)); \ } while (0) +/* + * Modify bits in a sysreg. Bits in the clear mask are zeroed, then bits in the + * set mask are set. Other bits are left as-is. + */ +#define sysreg_clear_set(sysreg, clear, set) do { \ + u64 __scs_val = read_sysreg(sysreg); \ + u64 __scs_new = (__scs_val & ~(u64)(clear)) | (set); \ + if (__scs_new != __scs_val) \ + write_sysreg(__scs_new, sysreg); \ +} while (0) + static inline void config_sctlr_el1(u32 clear, u32 set) { u32 val;
Currently we have a couple of helpers to manipulate bits in particular sysregs: * config_sctlr_el1(u32 clear, u32 set) * change_cpacr(u64 val, u64 mask) The parameters of these differ in naming convention, order, and size, which is unfortunate. They also differ slightly in behaviour, as change_cpacr() skips the sysreg write if the bits are unchanged, which is a useful optimization when sysreg writes are expensive. Before we gain more yet another sysreg manipulation function, let's unify these with a common helper, providing a consistent order for clear/set operands, and the write skipping behaviour from change_cpacr(). Code will be migrated to the new helper in subsequent patches. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <dave.martin@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> --- arch/arm64/include/asm/sysreg.h | 11 +++++++++++ 1 file changed, 11 insertions(+)