File: /usr/src/linux/arch/i386/kernel/pci-dma.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 <asm/io.h>
15     
16     void *pci_alloc_consistent(struct pci_dev *hwdev, size_t size,
17     			   dma_addr_t *dma_handle)
18     {
19     	void *ret;
20     	int gfp = GFP_ATOMIC;
21     
22     	if (hwdev == NULL || hwdev->dma_mask != 0xffffffff)
23     		gfp |= GFP_DMA;
24     	ret = (void *)__get_free_pages(gfp, get_order(size));
25     
26     	if (ret != NULL) {
27     		memset(ret, 0, size);
28     		*dma_handle = virt_to_bus(ret);
29     	}
30     	return ret;
31     }
32     
33     void pci_free_consistent(struct pci_dev *hwdev, size_t size,
34     			 void *vaddr, dma_addr_t dma_handle)
35     {
36     	free_pages((unsigned long)vaddr, get_order(size));
37     }
38