ARM: dma-mapping: push buffer ownership down into dma-mapping.c
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-By: Santosh Shilimkar <santosh.shilimkar@ti.com>
diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index e850f5c..256ee1c 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -57,46 +57,57 @@
#endif
/*
- * Private support functions: these are not part of the API and are
- * liable to change. Drivers must not use these.
- */
-extern void dma_cache_maint(const void *kaddr, size_t size, int rw);
-extern void dma_cache_maint_page(struct page *page, unsigned long offset,
- size_t size, int rw);
-
-/*
* The DMA API is built upon the notion of "buffer ownership". A buffer
* is either exclusively owned by the CPU (and therefore may be accessed
* by it) or exclusively owned by the DMA device. These helper functions
* represent the transitions between these two ownership states.
*
- * As above, these are private support functions and not part of the API.
- * Drivers must not use these.
+ * Note, however, that on later ARMs, this notion does not work due to
+ * speculative prefetches. We model our approach on the assumption that
+ * the CPU does do speculative prefetches, which means we clean caches
+ * before transfers and delay cache invalidation until transfer completion.
+ *
+ * Private support functions: these are not part of the API and are
+ * liable to change. Drivers must not use these.
*/
static inline void __dma_single_cpu_to_dev(const void *kaddr, size_t size,
enum dma_data_direction dir)
{
+ extern void ___dma_single_cpu_to_dev(const void *, size_t,
+ enum dma_data_direction);
+
if (!arch_is_coherent())
- dma_cache_maint(kaddr, size, dir);
+ ___dma_single_cpu_to_dev(kaddr, size, dir);
}
static inline void __dma_single_dev_to_cpu(const void *kaddr, size_t size,
enum dma_data_direction dir)
{
- /* nothing to do */
+ extern void ___dma_single_dev_to_cpu(const void *, size_t,
+ enum dma_data_direction);
+
+ if (!arch_is_coherent())
+ ___dma_single_dev_to_cpu(kaddr, size, dir);
}
static inline void __dma_page_cpu_to_dev(struct page *page, unsigned long off,
size_t size, enum dma_data_direction dir)
{
+ extern void ___dma_page_cpu_to_dev(struct page *, unsigned long,
+ size_t, enum dma_data_direction);
+
if (!arch_is_coherent())
- dma_cache_maint_page(page, off, size, dir);
+ ___dma_page_cpu_to_dev(page, off, size, dir);
}
static inline void __dma_page_dev_to_cpu(struct page *page, unsigned long off,
size_t size, enum dma_data_direction dir)
{
- /* nothing to do */
+ extern void ___dma_page_dev_to_cpu(struct page *, unsigned long,
+ size_t, enum dma_data_direction);
+
+ if (!arch_is_coherent())
+ ___dma_page_dev_to_cpu(page, off, size, dir);
}
/*