dma.c

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/*
 * Dynamic DMA mapping support.
 *
 * On cris there is no hardware dynamic DMA address translation,
 * so consistent alloc/free are merely page allocation/freeing.
 * The rest of the dynamic DMA mapping interface is implemented
 * in asm/pci.h.
 *
 * Borrowed from i386.
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <linux/gfp.h>
#include <asm/io.h>

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

    if (dma_alloc_from_coherent(dev, size, dma_handle, &ret))
        return ret;

    if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff))
        gfp |= GFP_DMA;

    ret = (void *)__get_free_pages(gfp, order);

    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)
{
    int order = get_order(size);

    if (!dma_release_from_coherent(dev, order, vaddr))
        free_pages((unsigned long)vaddr, order);
}