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dma.c

/*
 * 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/vmalloc.h>

#include <asm/pgalloc.h>

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;
}
EXPORT_SYMBOL(dma_alloc_coherent);

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);
}
EXPORT_SYMBOL(dma_free_coherent);

inline 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:
            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);

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