dma-iommu.c

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/*
 * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation
 *
 * Provide default implementations of the DMA mapping callbacks for
 * busses using the iommu infrastructure
 */

#include <linux/export.h>
#include <asm/iommu.h>

/*
 * Generic iommu implementation
 */

/* Allocates a contiguous real buffer and creates mappings over it.
 * Returns the virtual address of the buffer and sets dma_handle
 * to the dma address (mapping) of the first page.
 */
static void *dma_iommu_alloc_coherent(struct device *dev, size_t size,
                      dma_addr_t *dma_handle, gfp_t flag,
                      struct dma_attrs *attrs)
{
    return iommu_alloc_coherent(dev, get_iommu_table_base(dev), size,
                    dma_handle, dev->coherent_dma_mask, flag,
                    dev_to_node(dev));
}

static void dma_iommu_free_coherent(struct device *dev, size_t size,
                    void *vaddr, dma_addr_t dma_handle,
                    struct dma_attrs *attrs)
{
    iommu_free_coherent(get_iommu_table_base(dev), size, vaddr, dma_handle);
}

/* Creates TCEs for a user provided buffer.  The user buffer must be
 * contiguous real kernel storage (not vmalloc).  The address passed here
 * comprises a page address and offset into that page. The dma_addr_t
 * returned will point to the same byte within the page as was passed in.
 */
static dma_addr_t dma_iommu_map_page(struct device *dev, struct page *page,
                     unsigned long offset, size_t size,
                     enum dma_data_direction direction,
                     struct dma_attrs *attrs)
{
    return iommu_map_page(dev, get_iommu_table_base(dev), page, offset,
                  size, device_to_mask(dev), direction, attrs);
}


static void dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
                 size_t size, enum dma_data_direction direction,
                 struct dma_attrs *attrs)
{
    iommu_unmap_page(get_iommu_table_base(dev), dma_handle, size, direction,
             attrs);
}


static int dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
                int nelems, enum dma_data_direction direction,
                struct dma_attrs *attrs)
{
    return iommu_map_sg(dev, get_iommu_table_base(dev), sglist, nelems,
                device_to_mask(dev), direction, attrs);
}

static void dma_iommu_unmap_sg(struct device *dev, struct scatterlist *sglist,
        int nelems, enum dma_data_direction direction,
        struct dma_attrs *attrs)
{
    iommu_unmap_sg(get_iommu_table_base(dev), sglist, nelems, direction,
               attrs);
}

/* We support DMA to/from any memory page via the iommu */
static int dma_iommu_dma_supported(struct device *dev, u64 mask)
{
    struct iommu_table *tbl = get_iommu_table_base(dev);

    if (!tbl) {
        dev_info(dev, "Warning: IOMMU dma not supported: mask 0x%08llx"
            ", table unavailable\n", mask);
        return 0;
    }

    if (tbl->it_offset > (mask >> IOMMU_PAGE_SHIFT)) {
        dev_info(dev, "Warning: IOMMU offset too big for device mask\n");
        dev_info(dev, "mask: 0x%08llx, table offset: 0x%08lx\n",
                mask, tbl->it_offset << IOMMU_PAGE_SHIFT);
        return 0;
    } else
        return 1;
}

static u64 dma_iommu_get_required_mask(struct device *dev)
{
    struct iommu_table *tbl = get_iommu_table_base(dev);
    u64 mask;
    if (!tbl)
        return 0;

    mask = 1ULL < (fls_long(tbl->it_offset + tbl->it_size) - 1);
    mask += mask - 1;

    return mask;
}

struct dma_map_ops dma_iommu_ops = {
    .alloc          = dma_iommu_alloc_coherent,
    .free           = dma_iommu_free_coherent,
    .mmap           = dma_direct_mmap_coherent,
    .map_sg         = dma_iommu_map_sg,
    .unmap_sg       = dma_iommu_unmap_sg,
    .dma_supported      = dma_iommu_dma_supported,
    .map_page       = dma_iommu_map_page,
    .unmap_page     = dma_iommu_unmap_page,
    .get_required_mask  = dma_iommu_get_required_mask,
};
EXPORT_SYMBOL(dma_iommu_ops);