From c5ca95b507c8a2a69e49eeda539b41bd76922d7f Mon Sep 17 00:00:00 2001 From: Ezequiel Garcia Date: Wed, 18 Dec 2013 23:08:52 +0100 Subject: ARM: 7930/1: Introduce atomic MMIO modify Some SoC have MMIO regions that are shared across orthogonal subsystems. This commit implements a possible solution for the thread-safe access of such regions through a spinlock-protected API. Concurrent access is protected with a single spinlock for the entire MMIO address space. While this protects shared-registers, it also serializes access to unrelated/unshared registers. We add relaxed and non-relaxed variants, by using writel_relaxed and writel, respectively. The rationale for this is that some users may not require register write completion but only thread-safe access to a register. Tested-by: Sebastian Hesselbarth Acked-by: Jason Cooper Acked-by: Catalin Marinas Signed-off-by: Ezequiel Garcia Signed-off-by: Russell King --- arch/arm/include/asm/io.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/arm/include') diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h index fbeb39c869e9..8aa4cca74501 100644 --- a/arch/arm/include/asm/io.h +++ b/arch/arm/include/asm/io.h @@ -37,6 +37,12 @@ #define isa_page_to_bus page_to_phys #define isa_bus_to_virt phys_to_virt +/* + * Atomic MMIO-wide IO modify + */ +extern void atomic_io_modify(void __iomem *reg, u32 mask, u32 set); +extern void atomic_io_modify_relaxed(void __iomem *reg, u32 mask, u32 set); + /* * Generic IO read/write. These perform native-endian accesses. Note * that some architectures will want to re-define __raw_{read,write}w. -- cgit v1.2.3