From 1ad77a876da48331451698cc4172c90ab9b6372f Mon Sep 17 00:00:00 2001 From: Lennert Buytenhek Date: Fri, 5 Sep 2008 13:17:11 +0100 Subject: [ARM] 5241/1: provide ioremap_wc() This patch provides an ARM implementation of ioremap_wc(). We use different page table attributes depending on which CPU we are running on: - Non-XScale ARMv5 and earlier systems: The ARMv5 ARM documents four possible mapping types (CB=00/01/10/11). We can't use any of the cached memory types (CB=10/11), since that breaks coherency with peripheral devices. Both CB=00 and CB=01 are suitable for _wc, and CB=01 (Uncached/Buffered) allows the hardware more freedom than CB=00, so we'll use that. (The ARMv5 ARM seems to suggest that CB=01 is allowed to delay stores but isn't allowed to merge them, but there is no other mapping type we can use that allows the hardware to delay and merge stores, so we'll go with CB=01.) - XScale v1/v2 (ARMv5): same as the ARMv5 case above, with the slight difference that on these platforms, CB=01 actually _does_ allow merging stores. (If you want noncoalescing bufferable behavior on Xscale v1/v2, you need to use XCB=101.) - Xscale v3 (ARMv5) and ARMv6+: on these systems, we use TEXCB=00100 mappings (Inner/Outer Uncacheable in xsc3 parlance, Uncached Normal in ARMv6 parlance). The ARMv6 ARM explicitly says that any accesses to Normal memory can be merged, which makes Normal memory more suitable for _wc mappings than Device or Strongly Ordered memory, as the latter two mapping types are guaranteed to maintain transaction number, size and order. We use the Uncached variety of Normal mappings for the same reason that we can't use C=1 mappings on ARMv5. The xsc3 Architecture Specification documents TEXCB=00100 as being Uncacheable and allowing coalescing of writes, which is also just what we need. Signed-off-by: Lennert Buytenhek Signed-off-by: Russell King --- arch/arm/include/asm/mach/map.h | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'arch/arm/include/asm/mach/map.h') diff --git a/arch/arm/include/asm/mach/map.h b/arch/arm/include/asm/mach/map.h index 06f583b1399..9eb936e49cc 100644 --- a/arch/arm/include/asm/mach/map.h +++ b/arch/arm/include/asm/mach/map.h @@ -18,13 +18,13 @@ struct map_desc { unsigned int type; }; -/* types 0-3 are defined in asm/io.h */ -#define MT_CACHECLEAN 4 -#define MT_MINICLEAN 5 -#define MT_LOW_VECTORS 6 -#define MT_HIGH_VECTORS 7 -#define MT_MEMORY 8 -#define MT_ROM 9 +/* types 0-4 are defined in asm/io.h */ +#define MT_CACHECLEAN 5 +#define MT_MINICLEAN 6 +#define MT_LOW_VECTORS 7 +#define MT_HIGH_VECTORS 8 +#define MT_MEMORY 9 +#define MT_ROM 10 #define MT_NONSHARED_DEVICE MT_DEVICE_NONSHARED #define MT_IXP2000_DEVICE MT_DEVICE_IXP2000 -- cgit v1.2.3-70-g09d2