1/* Fallback functions when the main IOMMU code is not compiled in. This
  2   code is roughly equivalent to i386. */
  3#include <linux/dma-mapping.h>
  4#include <linux/scatterlist.h>
  5#include <linux/string.h>
  6#include <linux/init.h>
  7#include <linux/gfp.h>
  8#include <linux/pci.h>
  9#include <linux/mm.h>
 10
 11#include <asm/processor.h>
 12#include <asm/iommu.h>
 13#include <asm/dma.h>
 14
 15static int
 16check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size)
 17{
 18	if (hwdev && !dma_capable(hwdev, bus, size)) {
 19		if (*hwdev->dma_mask >= DMA_BIT_MASK(32))
 20			printk(KERN_ERR
 21			    "nommu_%s: overflow %Lx+%zu of device mask %Lx\n",
 22				name, (long long)bus, size,
 23				(long long)*hwdev->dma_mask);
 24		return 0;
 25	}
 26	return 1;
 27}
 28
 29static dma_addr_t nommu_map_page(struct device *dev, struct page *page,
 30				 unsigned long offset, size_t size,
 31				 enum dma_data_direction dir,
 32				 struct dma_attrs *attrs)
 33{
 34	dma_addr_t bus = page_to_phys(page) + offset;
 35	WARN_ON(size == 0);
 36	if (!check_addr("map_single", dev, bus, size))
 37		return DMA_ERROR_CODE;
 38	flush_write_buffers();
 39	return bus;
 40}
 41
 42/* Map a set of buffers described by scatterlist in streaming
 43 * mode for DMA.  This is the scatter-gather version of the
 44 * above pci_map_single interface.  Here the scatter gather list
 45 * elements are each tagged with the appropriate dma address
 46 * and length.  They are obtained via sg_dma_{address,length}(SG).
 47 *
 48 * NOTE: An implementation may be able to use a smaller number of
 49 *       DMA address/length pairs than there are SG table elements.
 50 *       (for example via virtual mapping capabilities)
 51 *       The routine returns the number of addr/length pairs actually
 52 *       used, at most nents.
 53 *
 54 * Device ownership issues as mentioned above for pci_map_single are
 55 * the same here.
 56 */
 57static int nommu_map_sg(struct device *hwdev, struct scatterlist *sg,
 58			int nents, enum dma_data_direction dir,
 59			struct dma_attrs *attrs)
 60{
 61	struct scatterlist *s;
 62	int i;
 63
 64	WARN_ON(nents == 0 || sg[0].length == 0);
 65
 66	for_each_sg(sg, s, nents, i) {
 67		BUG_ON(!sg_page(s));
 68		s->dma_address = sg_phys(s);
 69		if (!check_addr("map_sg", hwdev, s->dma_address, s->length))
 70			return 0;
 71		s->dma_length = s->length;
 72	}
 73	flush_write_buffers();
 74	return nents;
 75}
 76
 77static void nommu_sync_single_for_device(struct device *dev,
 78			dma_addr_t addr, size_t size,
 79			enum dma_data_direction dir)
 80{
 81	flush_write_buffers();
 82}
 83
 84
 85static void nommu_sync_sg_for_device(struct device *dev,
 86			struct scatterlist *sg, int nelems,
 87			enum dma_data_direction dir)
 88{
 89	flush_write_buffers();
 90}
 91
 92struct dma_map_ops nommu_dma_ops = {
 93	.alloc			= dma_generic_alloc_coherent,
 94	.free			= dma_generic_free_coherent,
 95	.map_sg			= nommu_map_sg,
 96	.map_page		= nommu_map_page,
 97	.sync_single_for_device = nommu_sync_single_for_device,
 98	.sync_sg_for_device	= nommu_sync_sg_for_device,
 99	.is_phys		= 1,
100};