diff options
| author | Ezequiel Garcia <ezequiel.garcia@free-electrons.com> | 2013-12-19 02:08:52 +0400 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2014-01-28 18:06:25 +0400 |
| commit | c5ca95b507c8a2a69e49eeda539b41bd76922d7f (patch) | |
| tree | 2ebbc82dcd1834300ec341a351a7f48ee5e5df0e /arch/arm/include | |
| parent | 668bc38669f9a6d5e91846e9435b22b196cee9d1 (diff) | |
| download | linux-c5ca95b507c8a2a69e49eeda539b41bd76922d7f.tar.xz | |
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 <sebastian.hesselbarth@gmail.com>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/io.h | 6 |
1 files changed, 6 insertions, 0 deletions
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 @@ -38,6 +38,12 @@ #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. */ |