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*参照元 [#v52e6933] #backlinks *説明 [#r1db2a79] -パス: [[linux-4.4.1/lib/swiotlb.c]] -FIXME: これは何？ --説明 **引数 [#a476b1c1] -struct device *dev -- --[[linux-4.4.1/device]] -struct page *page -- --[[linux-4.4.1/page]] -unsigned long offset -- -size_t size -- -enum dma_data_direction dir -- --[[linux-4.4.1/dma_data_direction]] -struct dma_attrs *attrs -- --[[linux-4.4.1/dma_attrs]] **返り値 [#p697a70c] -dma_addr_t -- --[[linux-4.4.1/dma_addr_t]] **参考 [#yc6f388f] *実装 [#qbf45789] /* * 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); - --[[linux-4.4.1/phys_addr_t]] --[[linux-4.4.1/page_to_phys()]] --[[linux-4.4.1/dma_addr_t]] --[[linux-4.4.1/phys_to_dma()]] BUG_ON(dir == DMA_NONE); - --[[linux-4.4.1/BUG_ON()]] /* * 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; - --[[linux-4.4.1/dma_capable()]] --[[linux-4.4.1/swiotlb_force(global)]] trace_swiotlb_bounced(dev, dev_addr, size, swiotlb_force); - --[[linux-4.4.1/trace_swiotlb_bounced()]] /* 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); } - --[[linux-4.4.1/map_single()]] --[[linux-4.4.1/swiotlb_full()]] --[[linux-4.4.1/io_tlb_overflow_buffer(global)]] 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); } - --[[linux-4.4.1/swiotlb_tbl_unmap_single()]] return dev_addr; } EXPORT_SYMBOL_GPL(swiotlb_map_page); - --[[linux-4.4.1/EXPORT_SYMBOL_GPL()]] *コメント [#w29f4f1a]
