1/* Fallback functions when the main IOMMU code is not compiled in. This 2 code is roughly equivalent to i386. */ 3#include <linux/mm.h> 4#include <linux/init.h> 5#include <linux/pci.h> 6#include <linux/string.h> 7#include <linux/dma-mapping.h> 8 9#include <asm/proto.h> 10#include <asm/processor.h> 11#include <asm/dma.h> 12 13static int 14check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size) 15{ 16 if (hwdev && bus + size > *hwdev->dma_mask) { 17 if (*hwdev->dma_mask >= DMA_32BIT_MASK) 18 printk(KERN_ERR 19 "nommu_%s: overflow %Lx+%zu of device mask %Lx\n", 20 name, (long long)bus, size, 21 (long long)*hwdev->dma_mask); 22 return 0; 23 } 24 return 1; 25} 26 27static dma_addr_t 28nommu_map_single(struct device *hwdev, void *ptr, size_t size, 29 int direction) 30{ 31 dma_addr_t bus = virt_to_bus(ptr); 32 if (!check_addr("map_single", hwdev, bus, size)) 33 return bad_dma_address; 34 return bus; 35} 36 37void nommu_unmap_single(struct device *dev, dma_addr_t addr,size_t size, 38 int direction) 39{ 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 */ 57int nommu_map_sg(struct device *hwdev, struct scatterlist *sg, 58 int nents, int direction) 59{ 60 int i; 61 62 for (i = 0; i < nents; i++ ) { 63 struct scatterlist *s = &sg[i]; 64 BUG_ON(!s->page); 65 s->dma_address = virt_to_bus(page_address(s->page) +s->offset); 66 if (!check_addr("map_sg", hwdev, s->dma_address, s->length)) 67 return 0; 68 s->dma_length = s->length; 69 } 70 return nents; 71} 72 73/* Unmap a set of streaming mode DMA translations. 74 * Again, cpu read rules concerning calls here are the same as for 75 * pci_unmap_single() above. 76 */ 77void nommu_unmap_sg(struct device *dev, struct scatterlist *sg, 78 int nents, int dir) 79{ 80} 81 82const struct dma_mapping_ops nommu_dma_ops = { 83 .map_single = nommu_map_single, 84 .unmap_single = nommu_unmap_single, 85 .map_sg = nommu_map_sg, 86 .unmap_sg = nommu_unmap_sg, 87 .is_phys = 1, 88}; 89 90void __init no_iommu_init(void) 91{ 92 if (dma_ops) 93 return; 94 95 force_iommu = 0; /* no HW IOMMU */ 96 dma_ops = &nommu_dma_ops; 97} 98