参照元†
- struct device *dev
- struct page *page
- unsigned long offset
- size_t size
- enum dma_data_direction dir
- struct dma_attrs *attrs
返り値†
/*
* Map a single buffer of the indicated size for DMA in streaming mode. The
* physical address to use is returned.
*
* Once the device is given the dma address, the device owns this memory until
* either swiotlb_unmap_page or swiotlb_dma_sync_single is performed.
*/
dma_addr_t swiotlb_map_page(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir,
struct dma_attrs *attrs)
{
phys_addr_t map, phys = page_to_phys(page) + offset;
dma_addr_t dev_addr = phys_to_dma(dev, phys);
BUG_ON(dir == DMA_NONE);
/*
* If the address happens to be in the device's DMA window,
* we can safely return the device addr and not worry about bounce
* buffering it.
*/
if (dma_capable(dev, dev_addr, size) && !swiotlb_force)
return dev_addr;
trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force);
/* Oh well, have to allocate and map a bounce buffer. */
map = map_single(dev, phys, size, dir);
if (map == SWIOTLB_MAP_ERROR) {
swiotlb_full(dev, size, dir, 1);
return phys_to_dma(dev, io_tlb_overflow_buffer);
}
dev_addr = phys_to_dma(dev, map);
/* Ensure that the address returned is DMA'ble */
if (!dma_capable(dev, dev_addr, size)) {
swiotlb_tbl_unmap_single(dev, map, size, dir);
return phys_to_dma(dev, io_tlb_overflow_buffer);
}
return dev_addr;
}
EXPORT_SYMBOL_GPL(swiotlb_map_page);
コメント†