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 /* 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);
  20
  21 void *dma_alloc_coherent(struct device *dev, size_t size,
  22                            dma_addr_t *dma_handle, gfp_t gfp)
  23 {
  24         void *ret;
  25         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  26         int order = get_order(size);
  27         /* ignore region specifiers */
  28         gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
  29
  30         if (mem) {
  31                 int page = bitmap_find_free_region(mem->bitmap, mem->size,
  32                                                      order);
  33                 if (page >= 0) {
  34                         *dma_handle = mem->device_base + (page << PAGE_SHIFT);
  35                         ret = mem->virt_base + (page << PAGE_SHIFT);
  36                         memset(ret, 0, size);
  37                         return ret;
  38                 }
  39                 if (mem->flags & DMA_MEMORY_EXCLUSIVE)
  40                         return NULL;
  41         }
  42
  43         if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
  44                 gfp |= GFP_DMA;
  45
  46         ret = (void *)__get_free_pages(gfp, order);
  47
  48         if (ret != NULL) {
  49                 memset(ret, 0, size);
  50                 *dma_handle = virt_to_phys(ret);
  51         }
  52         return ret;
  53 }
  54 EXPORT_SYMBOL(dma_alloc_coherent);
  55
  56 void dma_free_coherent(struct device *dev, size_t size,
  57                          void *vaddr, dma_addr_t dma_handle)
  58 {
  59         struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
  60         int order = get_order(size);
  61
  62         WARN_ON(irqs_disabled());       /* for portability */
  63         if (mem && vaddr >= mem->virt_base && vaddr < (mem->virt_base + (mem->size << PAGE_SHIFT))) {
  64                 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
  65
  66                 bitmap_release_region(mem->bitmap, page, order);
  67         } else
  68                 free_pages((unsigned long)vaddr, order);
  69 }
  70 EXPORT_SYMBOL(dma_free_coherent);