/*
       * Dynamic DMA mapping support.
       *
       * On i386 there is no hardware dynamic DMA address translation,
       * so consistent alloc/free are merely page allocation/freeing.
       * The rest of the dynamic DMA mapping interface is implemented
       * in asm/pci.h.
       */
      
      #include <linux/types.h>
      #include <linux/mm.h>
      #include <linux/string.h>
      #include <linux/pci.h>
      #include <asm/io.h>
      
  16  void *pci_alloc_consistent(struct pci_dev *hwdev, size_t size,
      			   dma_addr_t *dma_handle)
      {
      	void *ret;
      	int gfp = GFP_ATOMIC;
      
  22  	if (hwdev == NULL || hwdev->dma_mask != 0xffffffff)
      		gfp |= GFP_DMA;
      	ret = (void *)__get_free_pages(gfp, get_order(size));
      
  26  	if (ret != NULL) {
      		memset(ret, 0, size);
      		*dma_handle = virt_to_bus(ret);
      	}
  30  	return ret;
      }
      
  33  void pci_free_consistent(struct pci_dev *hwdev, size_t size,
      			 void *vaddr, dma_addr_t dma_handle)
      {
      	free_pages((unsigned long)vaddr, get_order(size));
      }