[PATCH v2 1/4] arm64: introduce sysreg_clear_set()

On Fri, Jun 15, 2018 at 05:21:25PM +0100, Catalin Marinas wrote:

On Fri, Jun 15, 2018 at 04:47:23PM +0100, Dave P Martin wrote:

quoted

From: Mark Rutland <mark.rutland@arm.com>

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>
Reviewed-by: Dave Martin <dave.martin@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <redacted>

Since you are submitting this patch, it should have your signed-off-by
as well. Other than that:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Oops, added locally.

I had considered this optional if the patch was unmodified from the
original author, but I guess I at least applied it on a different base.
In any case, I can see why it would be considered mandatory.

Cheers
---Dave