1 files changed, 60 insertions, 19 deletions

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index a96300bf83fd..256ee1c9f51a 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -57,18 +57,58 @@ static inline dma_addr_t virt_to_dma(struct device *dev, void *addr)
 #endif
 
 /*
- * DMA-consistent mapping functions.  These allocate/free a region of
- * uncached, unwrite-buffered mapped memory space for use with DMA
- * devices.  This is the "generic" version.  The PCI specific version
- * is in pci.h
+ * 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.
  *
- * Note: Drivers should NOT use this function directly, as it will break
- * platforms with CONFIG_DMABOUNCE.
- * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
+ * 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.
  */
-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);
+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_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)
+{
+        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_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)
+{
+        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);
+}
 
 /*
  * Return whether the given device DMA address mask can be supported
@@ -304,8 +344,7 @@ static inline dma_addr_t dma_map_single(struct device *dev, void *cpu_addr,
 {
         BUG_ON(!valid_dma_direction(dir));
 
-        if (!arch_is_coherent())
-                dma_cache_maint(cpu_addr, size, dir);
+        __dma_single_cpu_to_dev(cpu_addr, size, dir);
 
         return virt_to_dma(dev, cpu_addr);
 }
@@ -329,8 +368,7 @@ static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
 {
         BUG_ON(!valid_dma_direction(dir));
 
-        if (!arch_is_coherent())
-                dma_cache_maint_page(page, offset, size, dir);
+        __dma_page_cpu_to_dev(page, offset, size, dir);
 
         return page_to_dma(dev, page) + offset;
 }
@@ -352,7 +390,7 @@ static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
 static inline void dma_unmap_single(struct device *dev, dma_addr_t handle,
                 size_t size, enum dma_data_direction dir)
 {
-        /* nothing to do */
+        __dma_single_dev_to_cpu(dma_to_virt(dev, handle), size, dir);
 }
 
 /**
@@ -372,7 +410,8 @@ static inline void dma_unmap_single(struct device *dev, dma_addr_t handle,
 static inline void dma_unmap_page(struct device *dev, dma_addr_t handle,
                 size_t size, enum dma_data_direction dir)
 {
-        /* nothing to do */
+        __dma_page_dev_to_cpu(dma_to_page(dev, handle), handle & ~PAGE_MASK,
+                size, dir);
 }
 #endif /* CONFIG_DMABOUNCE */
 
@@ -400,7 +439,10 @@ static inline void dma_sync_single_range_for_cpu(struct device *dev,
 {
         BUG_ON(!valid_dma_direction(dir));
 
-        dmabounce_sync_for_cpu(dev, handle, offset, size, dir);
+        if (!dmabounce_sync_for_cpu(dev, handle, offset, size, dir))
+                return;
+
+        __dma_single_dev_to_cpu(dma_to_virt(dev, handle) + offset, size, dir);
 }
 
 static inline void dma_sync_single_range_for_device(struct device *dev,
@@ -412,8 +454,7 @@ static inline void dma_sync_single_range_for_device(struct device *dev,
         if (!dmabounce_sync_for_device(dev, handle, offset, size, dir))
                 return;
 
-        if (!arch_is_coherent())
-                dma_cache_maint(dma_to_virt(dev, handle) + offset, size, dir);
+        __dma_single_cpu_to_dev(dma_to_virt(dev, handle) + offset, size, dir);
 }
 
 static inline void dma_sync_single_for_cpu(struct device *dev,