2 * Dynamic DMA mapping support.
4 * On i386 there is no hardware dynamic DMA address translation,
5 * so consistent alloc/free are merely page allocation/freeing.
6 * The rest of the dynamic DMA mapping interface is implemented
10 #include <linux/types.h>
12 #include <linux/string.h>
13 #include <linux/pci.h>
14 #include <linux/module.h>
17 /* For i386, we make it point to the NULL address */
18 dma_addr_t bad_dma_address __read_mostly = 0x0;
19 EXPORT_SYMBOL(bad_dma_address);
21 static int dma_alloc_from_coherent_mem(struct device *dev, ssize_t size,
22 dma_addr_t *dma_handle, void **ret)
24 struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
25 int order = get_order(size);
28 int page = bitmap_find_free_region(mem->bitmap, mem->size,
31 *dma_handle = mem->device_base + (page << PAGE_SHIFT);
32 *ret = mem->virt_base + (page << PAGE_SHIFT);
33 memset(*ret, 0, size);
35 if (mem->flags & DMA_MEMORY_EXCLUSIVE)
41 static int dma_release_coherent(struct device *dev, int order, void *vaddr)
43 struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
45 if (mem && vaddr >= mem->virt_base && vaddr <
46 (mem->virt_base + (mem->size << PAGE_SHIFT))) {
47 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
49 bitmap_release_region(mem->bitmap, page, order);
55 void *dma_alloc_coherent(struct device *dev, size_t size,
56 dma_addr_t *dma_handle, gfp_t gfp)
59 int order = get_order(size);
60 /* ignore region specifiers */
61 gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
63 if (dma_alloc_from_coherent_mem(dev, size, dma_handle, &ret))
66 if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
69 ret = (void *)__get_free_pages(gfp, order);
73 *dma_handle = virt_to_phys(ret);
77 EXPORT_SYMBOL(dma_alloc_coherent);
79 void dma_free_coherent(struct device *dev, size_t size,
80 void *vaddr, dma_addr_t dma_handle)
82 int order = get_order(size);
84 WARN_ON(irqs_disabled()); /* for portability */
85 if (dma_release_coherent(dev, order, vaddr))
87 free_pages((unsigned long)vaddr, order);
89 EXPORT_SYMBOL(dma_free_coherent);