/* Fallback functions when the main IOMMU code is not compiled in. This code is roughly equivalent to i386. */ #include <linux/mm.h> #include <linux/init.h> #include <linux/pci.h> #include <linux/string.h> #include <linux/dma-mapping.h> #include <linux/scatterlist.h> #include <asm/gart.h> #include <asm/processor.h> #include <asm/dma.h> static int check_addr(char *name, struct device *hwdev, dma_addr_t bus, size_t size) { if (hwdev && bus + size > *hwdev->dma_mask) { if (*hwdev->dma_mask >= DMA_32BIT_MASK) printk(KERN_ERR "nommu_%s: overflow %Lx+%zu of device mask %Lx\n", name, (long long)bus, size, (long long)*hwdev->dma_mask); return 0; } return 1; } static dma_addr_t nommu_map_single(struct device *hwdev, void *ptr, size_t size, int direction) { dma_addr_t bus = virt_to_bus(ptr); if (!check_addr("map_single", hwdev, bus, size)) return bad_dma_address; return bus; } static void nommu_unmap_single(struct device *dev, dma_addr_t addr,size_t size, int direction) { } /* Map a set of buffers described by scatterlist in streaming * mode for DMA. This is the scatter-gather version of the * above pci_map_single interface. Here the scatter gather list * elements are each tagged with the appropriate dma address * and length. They are obtained via sg_dma_{address,length}(SG). * * NOTE: An implementation may be able to use a smaller number of * DMA address/length pairs than there are SG table elements. * (for example via virtual mapping capabilities) * The routine returns the number of addr/length pairs actually * used, at most nents. * * Device ownership issues as mentioned above for pci_map_single are * the same here. */ static int nommu_map_sg(struct device *hwdev, struct scatterlist *sg, int nents, int direction) { struct scatterlist *s; int i; for_each_sg(sg, s, nents, i) { BUG_ON(!sg_page(s)); s->dma_address = virt_to_bus(sg_virt(s)); if (!check_addr("map_sg", hwdev, s->dma_address, s->length)) return 0; s->dma_length = s->length; } return nents; } /* Unmap a set of streaming mode DMA translations. * Again, cpu read rules concerning calls here are the same as for * pci_unmap_single() above. */ static void nommu_unmap_sg(struct device *dev, struct scatterlist *sg, int nents, int dir) { } const struct dma_mapping_ops nommu_dma_ops = { .map_single = nommu_map_single, .unmap_single = nommu_unmap_single, .map_sg = nommu_map_sg, .unmap_sg = nommu_unmap_sg, .is_phys = 1, }; void __init no_iommu_init(void) { if (dma_ops) return; force_iommu = 0; /* no HW IOMMU */ dma_ops = &nommu_dma_ops; }