From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave.Martin@arm.com (Dave Martin) Date: Thu, 14 Jun 2018 12:42:23 +0100 Subject: [PATCH 1/4] arm64: introduce sysreg_clear_set() In-Reply-To: <1528976039-25826-1-git-send-email-Dave.Martin@arm.com> References: <1528976039-25826-1-git-send-email-Dave.Martin@arm.com> Message-ID: <1528976546-25999-1-git-send-email-Dave.Martin@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Mark Rutland 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 Reviewed-by: Dave Martin Cc: Catalin Marinas Cc: Marc Zyngier --- 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 6171178..a8f8481 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -728,6 +728,17 @@ 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; -- 2.1.4