dma.c

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/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

#undef DEBUG

#include <linux/dma-mapping.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/export.h>

#include <asm/pgalloc.h>

#if defined(CONFIG_MMU) && !defined(CONFIG_COLDFIRE)

void *dma_alloc_coherent(struct device *dev, size_t size,
             dma_addr_t *handle, gfp_t flag)
{
    struct page *page, **map;
    pgprot_t pgprot;
    void *addr;
    int i, order;

    pr_debug("dma_alloc_coherent: %d,%x\n", size, flag);

    size = PAGE_ALIGN(size);
    order = get_order(size);

    page = alloc_pages(flag, order);
    if (!page)
        return NULL;

    *handle = page_to_phys(page);
    map = kmalloc(sizeof(struct page *) << order, flag & ~__GFP_DMA);
    if (!map) {
        __free_pages(page, order);
        return NULL;
    }
    split_page(page, order);

    order = 1 << order;
    size >>= PAGE_SHIFT;
    map[0] = page;
    for (i = 1; i < size; i++)
        map[i] = page + i;
    for (; i < order; i++)
        __free_page(page + i);
    pgprot = __pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY);
    if (CPU_IS_040_OR_060)
        pgprot_val(pgprot) |= _PAGE_GLOBAL040 | _PAGE_NOCACHE_S;
    else
        pgprot_val(pgprot) |= _PAGE_NOCACHE030;
    addr = vmap(map, size, VM_MAP, pgprot);
    kfree(map);

    return addr;
}

void dma_free_coherent(struct device *dev, size_t size,
               void *addr, dma_addr_t handle)
{
    pr_debug("dma_free_coherent: %p, %x\n", addr, handle);
    vfree(addr);
}

#else

#include <asm/cacheflush.h>

void *dma_alloc_coherent(struct device *dev, size_t size,
               dma_addr_t *dma_handle, gfp_t gfp)
{
    void *ret;
    /* ignore region specifiers */
    gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);

    if (dev == NULL || (*dev->dma_mask < 0xffffffff))
        gfp |= GFP_DMA;
    ret = (void *)__get_free_pages(gfp, get_order(size));

    if (ret != NULL) {
        memset(ret, 0, size);
        *dma_handle = virt_to_phys(ret);
    }
    return ret;
}

void dma_free_coherent(struct device *dev, size_t size,
             void *vaddr, dma_addr_t dma_handle)
{
    free_pages((unsigned long)vaddr, get_order(size));
}

#endif /* CONFIG_MMU && !CONFIG_COLDFIRE */

EXPORT_SYMBOL(dma_alloc_coherent);
EXPORT_SYMBOL(dma_free_coherent);

void dma_sync_single_for_device(struct device *dev, dma_addr_t handle,
                size_t size, enum dma_data_direction dir)
{
    switch (dir) {
    case DMA_BIDIRECTIONAL:
    case DMA_TO_DEVICE:
        cache_push(handle, size);
        break;
    case DMA_FROM_DEVICE:
        cache_clear(handle, size);
        break;
    default:
        if (printk_ratelimit())
            printk("dma_sync_single_for_device: unsupported dir %u\n", dir);
        break;
    }
}
EXPORT_SYMBOL(dma_sync_single_for_device);

void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nents,
                enum dma_data_direction dir)
{
    int i;

    for (i = 0; i < nents; sg++, i++)
        dma_sync_single_for_device(dev, sg->dma_address, sg->length, dir);
}
EXPORT_SYMBOL(dma_sync_sg_for_device);

dma_addr_t dma_map_single(struct device *dev, void *addr, size_t size,
              enum dma_data_direction dir)
{
    dma_addr_t handle = virt_to_bus(addr);

    dma_sync_single_for_device(dev, handle, size, dir);
    return handle;
}
EXPORT_SYMBOL(dma_map_single);

dma_addr_t dma_map_page(struct device *dev, struct page *page,
            unsigned long offset, size_t size,
            enum dma_data_direction dir)
{
    dma_addr_t handle = page_to_phys(page) + offset;

    dma_sync_single_for_device(dev, handle, size, dir);
    return handle;
}
EXPORT_SYMBOL(dma_map_page);

int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
           enum dma_data_direction dir)
{
    int i;

    for (i = 0; i < nents; sg++, i++) {
        sg->dma_address = sg_phys(sg);
        dma_sync_single_for_device(dev, sg->dma_address, sg->length, dir);
    }
    return nents;
}
EXPORT_SYMBOL(dma_map_sg);