arch/x86/kernel/pci-dma_32.c

   1 /*
   2  * Dynamic DMA mapping support.
   3  *
   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
   7  * in asm/pci.h.
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/mm.h>
  12 #include <linux/string.h>
  13 #include <linux/pci.h>
  14 #include <linux/module.h>
  15 #include <asm/io.h>
  16
  17 static int dma_alloc_from_coherent_mem(struct device *dev, ssize_t size,
  18                                        dma_addr_t *dma_handle, void **ret)
  19 {
  20         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  21         int order = get_order(size);
  22
  23         if (mem) {
  24                 int page = bitmap_find_free_region(mem->bitmap, mem->size,
  25                                                      order);
  26                 if (page >= 0) {
  27                         *dma_handle = mem->device_base + (page << PAGE_SHIFT);
  28                         *ret = mem->virt_base + (page << PAGE_SHIFT);
  29                         memset(*ret, 0, size);
  30                 }
  31                 if (mem->flags & DMA_MEMORY_EXCLUSIVE)
  32                         *ret = NULL;
  33         }
  34         return (mem != NULL);
  35 }
  36
  37 static int dma_release_coherent(struct device *dev, int order, void *vaddr)
  38 {
  39         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  40
  41         if (mem && vaddr >= mem->virt_base && vaddr <
  42                    (mem->virt_base + (mem->size << PAGE_SHIFT))) {
  43                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
  44
  45                 bitmap_release_region(mem->bitmap, page, order);
  46                 return 1;
  47         }
  48         return 0;
  49 }
  50
  51 void *dma_alloc_coherent(struct device *dev, size_t size,
  52                            dma_addr_t *dma_handle, gfp_t gfp)
  53 {
  54         void *ret = NULL;
  55         int order = get_order(size);
  56         /* ignore region specifiers */
  57         gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
  58
  59         if (dma_alloc_from_coherent_mem(dev, size, dma_handle, &ret))
  60                 return ret;
  61
  62         if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
  63                 gfp |= GFP_DMA;
  64
  65         ret = (void *)__get_free_pages(gfp, order);
  66
  67         if (ret != NULL) {
  68                 memset(ret, 0, size);
  69                 *dma_handle = virt_to_phys(ret);
  70         }
  71         return ret;
  72 }
  73 EXPORT_SYMBOL(dma_alloc_coherent);
  74
  75 void dma_free_coherent(struct device *dev, size_t size,
  76                          void *vaddr, dma_addr_t dma_handle)
  77 {
  78         int order = get_order(size);
  79
  80         WARN_ON(irqs_disabled());       /* for portability */
  81         if (dma_release_coherent(dev, order, vaddr))
  82                 return;
  83         if (dma_ops->unmap_single)
  84                 dma_ops->unmap_single(dev, dma_handle, size, 0);
  85         free_pages((unsigned long)vaddr, order);
  86 }
  87 EXPORT_SYMBOL(dma_free_coherent);