参照元†
- struct device *dev
- ssize_t size
- dma_addr_t *dma_handle
- void **ret
返り値†
ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY 有効: drivers/base/dma-coherent.c†
/**
* 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;
int order = get_order(size);
unsigned long flags;
int pageno;
if (!dev)
return 0;
mem = dev->dma_mem;
if (!mem)
return 0;
*ret = NULL;
spin_lock_irqsave(&mem->spinlock, flags);
if (unlikely(size > (mem->size << PAGE_SHIFT)))
goto err;
pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
if (unlikely(pageno < 0))
goto err;
/*
* Memory was found in the per-device area.
*/
*dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
*ret = mem->virt_base + (pageno << PAGE_SHIFT);
memset(*ret, 0, size);
spin_unlock_irqrestore(&mem->spinlock, flags);
return 1;
err:
spin_unlock_irqrestore(&mem->spinlock, flags);
/*
* In the case where the allocation can not be satisfied from the
* per-device area, try to fall back to generic memory if the
* constraints allow it.
*/
return mem->flags & DMA_MEMORY_EXCLUSIVE;
}
EXPORT_SYMBOL(dma_alloc_from_coherent);
ARCH_HAS_DMA_DECLARE_COHERENT_MEMORY 無効: include/asm-generic/dma-coherent.h†
#define dma_alloc_from_coherent(dev, size, handle, ret) (0)
コメント†