1/*
  2 * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation
  3 *
  4 * Provide default implementations of the DMA mapping callbacks for
  5 * busses using the iommu infrastructure
  6 */
  7
  8#include <linux/export.h>
  9#include <asm/iommu.h>
 10
 11/*
 12 * Generic iommu implementation
 13 */
 14
 15/* Allocates a contiguous real buffer and creates mappings over it.
 16 * Returns the virtual address of the buffer and sets dma_handle
 17 * to the dma address (mapping) of the first page.
 18 */
 19static void *dma_iommu_alloc_coherent(struct device *dev, size_t size,
 20				      dma_addr_t *dma_handle, gfp_t flag,
 21				      struct dma_attrs *attrs)
 22{
 23	return iommu_alloc_coherent(dev, get_iommu_table_base(dev), size,
 24				    dma_handle, dev->coherent_dma_mask, flag,
 25				    dev_to_node(dev));
 26}
 27
 28static void dma_iommu_free_coherent(struct device *dev, size_t size,
 29				    void *vaddr, dma_addr_t dma_handle,
 30				    struct dma_attrs *attrs)
 31{
 32	iommu_free_coherent(get_iommu_table_base(dev), size, vaddr, dma_handle);
 33}
 34
 35/* Creates TCEs for a user provided buffer.  The user buffer must be
 36 * contiguous real kernel storage (not vmalloc).  The address passed here
 37 * comprises a page address and offset into that page. The dma_addr_t
 38 * returned will point to the same byte within the page as was passed in.
 39 */
 40static dma_addr_t dma_iommu_map_page(struct device *dev, struct page *page,
 41				     unsigned long offset, size_t size,
 42				     enum dma_data_direction direction,
 43				     struct dma_attrs *attrs)
 44{
 45	return iommu_map_page(dev, get_iommu_table_base(dev), page, offset,
 46			      size, device_to_mask(dev), direction, attrs);
 47}
 48
 49
 50static void dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
 51				 size_t size, enum dma_data_direction direction,
 52				 struct dma_attrs *attrs)
 53{
 54	iommu_unmap_page(get_iommu_table_base(dev), dma_handle, size, direction,
 55			 attrs);
 56}
 57
 58
 59static int dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
 60			    int nelems, enum dma_data_direction direction,
 61			    struct dma_attrs *attrs)
 62{
 63	return iommu_map_sg(dev, get_iommu_table_base(dev), sglist, nelems,
 64			    device_to_mask(dev), direction, attrs);
 65}
 66
 67static void dma_iommu_unmap_sg(struct device *dev, struct scatterlist *sglist,
 68		int nelems, enum dma_data_direction direction,
 69		struct dma_attrs *attrs)
 70{
 71	iommu_unmap_sg(get_iommu_table_base(dev), sglist, nelems, direction,
 72		       attrs);
 73}
 74
 75/* We support DMA to/from any memory page via the iommu */
 76static int dma_iommu_dma_supported(struct device *dev, u64 mask)
 77{
 78	struct iommu_table *tbl = get_iommu_table_base(dev);
 79
 80	if (!tbl) {
 81		dev_info(dev, "Warning: IOMMU dma not supported: mask 0x%08llx"
 82			", table unavailable\n", mask);
 83		return 0;
 84	}
 85
 86	if ((tbl->it_offset + tbl->it_size) > (mask >> IOMMU_PAGE_SHIFT)) {
 87		dev_info(dev, "Warning: IOMMU window too big for device mask\n");
 88		dev_info(dev, "mask: 0x%08llx, table end: 0x%08lx\n",
 89				mask, (tbl->it_offset + tbl->it_size) <<
 90				IOMMU_PAGE_SHIFT);
 91		return 0;
 92	} else
 93		return 1;
 94}
 95
 96static u64 dma_iommu_get_required_mask(struct device *dev)
 97{
 98	struct iommu_table *tbl = get_iommu_table_base(dev);
 99	u64 mask;
100	if (!tbl)
101		return 0;
102
103	mask = 1ULL < (fls_long(tbl->it_offset + tbl->it_size) - 1);
104	mask += mask - 1;
105
106	return mask;
107}
108
109struct dma_map_ops dma_iommu_ops = {
110	.alloc			= dma_iommu_alloc_coherent,
111	.free			= dma_iommu_free_coherent,
112	.map_sg			= dma_iommu_map_sg,
113	.unmap_sg		= dma_iommu_unmap_sg,
114	.dma_supported		= dma_iommu_dma_supported,
115	.map_page		= dma_iommu_map_page,
116	.unmap_page		= dma_iommu_unmap_page,
117	.get_required_mask	= dma_iommu_get_required_mask,
118};
119EXPORT_SYMBOL(dma_iommu_ops);