dma.c

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

/* $Id: dma.c,v 1.1 2000/02/18 00:24:30 ralf Exp $
 *
 * Dynamic DMA mapping support.
 *
 * On RM200 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>.
 *
 * These routines assume that the RM has all it's memory at physical
 * addresses of < 512mb.
 */
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <asm/io.h>

void *pci_alloc_consistent(struct pci_dev *hwdev, size_t size,
			   dma_addr_t *dma_handle)
{
	void *ret;
	int gfp = GFP_ATOMIC;
	int order = get_order(size);

	if (hwdev == NULL || hwdev->dma_mask != 0xffffffff)
		gfp |= GFP_DMA;
	ret = (void *)__get_free_pages(gfp, order);

	if (ret != NULL) {
		memset(ret, 0, size);
		*dma_handle = virt_to_bus(ret);
	}
	dma_cache_wback_inv(ret, PAGE_SIZE << order);
	return KSEG1ADDR(ret);
}

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));
}