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dma.c

/*
 * 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 <asm/io.h>

struct dma_coherent_mem {
      void        *virt_base;
      u32         device_base;
      int         size;
      int         flags;
      unsigned long     *bitmap;
};

void *dma_alloc_coherent(struct device *dev, size_t size,
                     dma_addr_t *dma_handle, gfp_t gfp)
{
      void *ret;
      struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
      int order = get_order(size);
      /* ignore region specifiers */
      gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);

      if (mem) {
            int page = bitmap_find_free_region(mem->bitmap, mem->size,
                                         order);
            if (page >= 0) {
                  *dma_handle = mem->device_base + (page << PAGE_SHIFT);
                  ret = mem->virt_base + (page << PAGE_SHIFT);
                  memset(ret, 0, size);
                  return ret;
            }
            if (mem->flags & DMA_MEMORY_EXCLUSIVE)
                  return NULL;
      }

      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)
{
      struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
      int order = get_order(size);

      if (mem && vaddr >= mem->virt_base && vaddr < (mem->virt_base + (mem->size << PAGE_SHIFT))) {
            int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;

            bitmap_release_region(mem->bitmap, page, order);
      } else
            free_pages((unsigned long)vaddr, order);
}

int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
                        dma_addr_t device_addr, size_t size, int flags)
{
      void __iomem *mem_base;
      int pages = size >> PAGE_SHIFT;
      int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);

      if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
            goto out;
      if (!size)
            goto out;
      if (dev->dma_mem)
            goto out;

      /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */

      mem_base = ioremap(bus_addr, size);
      if (!mem_base)
            goto out;

      dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
      if (!dev->dma_mem)
            goto out;
      dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
      if (!dev->dma_mem->bitmap)
            goto free1_out;

      dev->dma_mem->virt_base = mem_base;
      dev->dma_mem->device_base = device_addr;
      dev->dma_mem->size = pages;
      dev->dma_mem->flags = flags;

      if (flags & DMA_MEMORY_MAP)
            return DMA_MEMORY_MAP;

      return DMA_MEMORY_IO;

 free1_out:
      kfree(dev->dma_mem);
 out:
      return 0;
}
EXPORT_SYMBOL(dma_declare_coherent_memory);

void dma_release_declared_memory(struct device *dev)
{
      struct dma_coherent_mem *mem = dev->dma_mem;

      if(!mem)
            return;
      dev->dma_mem = NULL;
      iounmap(mem->virt_base);
      kfree(mem->bitmap);
      kfree(mem);
}
EXPORT_SYMBOL(dma_release_declared_memory);

void *dma_mark_declared_memory_occupied(struct device *dev,
                              dma_addr_t device_addr, size_t size)
{
      struct dma_coherent_mem *mem = dev->dma_mem;
      int pages = (size + (device_addr & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
      int pos, err;

      if (!mem)
            return ERR_PTR(-EINVAL);

      pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
      err = bitmap_allocate_region(mem->bitmap, pos, get_order(pages));
      if (err != 0)
            return ERR_PTR(err);
      return mem->virt_base + (pos << PAGE_SHIFT);
}
EXPORT_SYMBOL(dma_mark_declared_memory_occupied);

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