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@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dave Martin <dave.martin@xxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
---
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
