From 23759dc6430428897a36c4d493f611eca55c9481 Mon Sep 17 00:00:00 2001 From: Lennert Buytenhek Date: Sun, 2 Apr 2006 00:07:39 +0100 Subject: [ARM] 3439/2: xsc3: add I/O coherency support Patch from Lennert Buytenhek This patch adds support for the I/O coherent cache available on the xsc3. The approach is to provide a simple API to determine whether the chipset supports coherency by calling arch_is_coherent() and then setting the appropriate system memory PTE and PMD bits. In addition, we call this API on dma_alloc_coherent() and dma_map_single() calls. A generic version exists that will compile out all the coherency-related code that is not needed on the majority of ARM systems. Note that we do not check for coherency in the dma_alloc_writecombine() function as that still requires a special PTE setting. We also don't touch dma_mmap_coherent() as that is a special ARM-only API that is by definition only used on non-coherent system. Signed-off-by: Deepak Saxena Signed-off-by: Lennert Buytenhek Signed-off-by: Russell King --- include/asm-arm/memory.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/asm-arm/memory.h') diff --git a/include/asm-arm/memory.h b/include/asm-arm/memory.h index afa5c3ea077c..2b3cf69b3ed9 100644 --- a/include/asm-arm/memory.h +++ b/include/asm-arm/memory.h @@ -234,6 +234,14 @@ static inline __deprecated void *bus_to_virt(unsigned long x) #define virt_to_dma(dev, addr) (__arch_virt_to_dma(dev, addr)) #endif +/* + * Optional coherency support. Currently used only by selected + * Intel XSC3-based systems. + */ +#ifndef arch_is_coherent +#define arch_is_coherent() 0 +#endif + #endif #include -- cgit v1.2.2