FreeBSD/Linux Kernel Cross Reference
sys/kernel/dma-coherent.c

     /*
      * Coherent per-device memory handling.
      * Borrowed from i386
      */
     #include <linux/kernel.h>
     #include <linux/dma-mapping.h>
     
     struct dma_coherent_mem {
             void            *virt_base;
            u32             device_base;
            int             size;
            int             flags;
            unsigned long   *bitmap;
    };
    
    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 = NULL;
            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:
            if (mem_base)
                    iounmap(mem_base);
            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 pos, err;
    
            size += device_addr & ~PAGE_MASK;
    
            if (!mem)
                    return ERR_PTR(-EINVAL);
    
            pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
            err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
            if (err != 0)
                    return ERR_PTR(err);
            return mem->virt_base + (pos << PAGE_SHIFT);
    }
    EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
    
    /**
     * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
     *
     * @dev:        device from which we allocate memory
     * @size:       size of requested memory area
     * @dma_handle: This will be filled with the correct dma handle
    * @ret:        This pointer will be filled with the virtual address
    *              to allocated area.
    *
    * This function should be only called from per-arch dma_alloc_coherent()
    * to support allocation from per-device coherent memory pools.
    *
    * Returns 0 if dma_alloc_coherent should continue with allocating from
    * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
    */
   int dma_alloc_from_coherent(struct device *dev, ssize_t size,
                                          dma_addr_t *dma_handle, void **ret)
   {
           struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
           int order = get_order(size);
   
           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);
                   } else if (mem->flags & DMA_MEMORY_EXCLUSIVE)
                           *ret = NULL;
           }
           return (mem != NULL);
   }
   EXPORT_SYMBOL(dma_alloc_from_coherent);
   
   /**
    * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
    * @dev:        device from which the memory was allocated
    * @order:      the order of pages allocated
    * @vaddr:      virtual address of allocated pages
    *
    * This checks whether the memory was allocated from the per-device
    * coherent memory pool and if so, releases that memory.
    *
    * Returns 1 if we correctly released the memory, or 0 if
    * dma_release_coherent() should proceed with releasing memory from
    * generic pools.
    */
   int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
   {
           struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
   
           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);
                   return 1;
           }
           return 0;
   }
   EXPORT_SYMBOL(dma_release_from_coherent);

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