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dma.c

/*
 * Dynamic DMA mapping support.
 *
 * We never have any address translations to worry about, so this
 * is just alloc/free.
 */

#include <linux/types.h>
#include <linux/mm.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#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));
}

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_TO_DEVICE:
            flush_dcache_range(handle, size);
            break;
      case DMA_FROM_DEVICE:
            /* Should be clear already */
            break;
      default:
            if (printk_ratelimit())
                  printk("dma_sync_single_for_device: unsupported dir %u\n", dir);
            break;
      }
}

EXPORT_SYMBOL(dma_sync_single_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_phys(addr);
      flush_dcache_range(handle, size);
      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);

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