X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fdma-coherent.c;h=038707404b76075866d6bccb5df015d9965762c4;hb=1092307d582a7566d23779c304cf86f3075ac5f0;hp=89a554cfd936b57573eb3c240ceb78b764ef1824;hpb=ee7e5516be4f2107535ad5a3d47d9c79f93661a2;p=safe%2Fjmp%2Flinux-2.6

diff --git a/kernel/dma-coherent.c b/kernel/dma-coherent.c
index 89a554c..0387074 100644
--- a/kernel/dma-coherent.c
+++ b/kernel/dma-coherent.c
@@ -77,41 +77,88 @@ void *dma_mark_declared_memory_occupied(struct device *dev,
 {
 	struct dma_coherent_mem *mem = dev->dma_mem;
 	int pos, err;
-	int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1);
 
-	pages >>= PAGE_SHIFT;
+	size += device_addr & ~PAGE_MASK;
 
 	if (!mem)
 		return ERR_PTR(-EINVAL);
 
 	pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
-	err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
+	err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
 	if (err != 0)
 		return ERR_PTR(err);
 	return mem->virt_base + (pos << PAGE_SHIFT);
 }
 EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 
+/**
+ * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
+ *
+ * @dev:	device from which we allocate memory
+ * @size:	size of requested memory area
+ * @dma_handle:	This will be filled with the correct dma handle
+ * @ret:	This pointer will be filled with the virtual address
+ * 		to allocated area.
+ *
+ * This function should be only called from per-arch dma_alloc_coherent()
+ * to support allocation from per-device coherent memory pools.
+ *
+ * Returns 0 if dma_alloc_coherent should continue with allocating from
+ * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
+ */
 int dma_alloc_from_coherent(struct device *dev, ssize_t size,
 				       dma_addr_t *dma_handle, void **ret)
 {
-	struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
+	struct dma_coherent_mem *mem;
 	int order = get_order(size);
+	int pageno;
 
-	if (mem) {
-		int page = bitmap_find_free_region(mem->bitmap, mem->size,
-						     order);
-		if (page >= 0) {
-			*dma_handle = mem->device_base + (page << PAGE_SHIFT);
-			*ret = mem->virt_base + (page << PAGE_SHIFT);
-			memset(*ret, 0, size);
-		}
-		if (mem->flags & DMA_MEMORY_EXCLUSIVE)
-			*ret = NULL;
+	if (!dev)
+		return 0;
+	mem = dev->dma_mem;
+	if (!mem)
+		return 0;
+	if (unlikely(size > mem->size))
+ 		return 0;
+
+	pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
+	if (pageno >= 0) {
+		/*
+		 * Memory was found in the per-device arena.
+		 */
+		*dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
+		*ret = mem->virt_base + (pageno << PAGE_SHIFT);
+		memset(*ret, 0, size);
+	} else if (mem->flags & DMA_MEMORY_EXCLUSIVE) {
+		/*
+		 * The per-device arena is exhausted and we are not
+		 * permitted to fall back to generic memory.
+		 */
+		*ret = NULL;
+	} else {
+		/*
+		 * The per-device arena is exhausted and we are
+		 * permitted to fall back to generic memory.
+		 */
+		 return 0;
 	}
-	return (mem != NULL);
+	return 1;
 }
-
+EXPORT_SYMBOL(dma_alloc_from_coherent);
+
+/**
+ * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
+ * @dev:	device from which the memory was allocated
+ * @order:	the order of pages allocated
+ * @vaddr:	virtual address of allocated pages
+ *
+ * This checks whether the memory was allocated from the per-device
+ * coherent memory pool and if so, releases that memory.
+ *
+ * Returns 1 if we correctly released the memory, or 0 if
+ * dma_release_coherent() should proceed with releasing memory from
+ * generic pools.
+ */
 int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 {
 	struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
@@ -125,3 +172,4 @@ int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
 	}
 	return 0;
 }
+EXPORT_SYMBOL(dma_release_from_coherent);