![[PukiWiki]](image/pukiwiki.png "[PukiWiki]")
*参照元 [#qcdc1c67] #backlinks *説明 [#gd685f2a] -パス: [[linux-4.4.1/lib/swiotlb.c]] -FIXME: これは何？ --説明 **引数 [#nfebf719] -struct device *hwdev -- --[[linux-4.4.1/device]] -dma_addr_t tbl_dma_addr -- --[[linux-4.4.1/dma_addr_t]] -phys_addr_t orig_addr -- --[[linux-4.4.1/phys_addr_t]] -size_t size -- -enum dma_data_direction dir -- --[[linux-4.4.1/dma_data_direction]] **返り値 [#fb9cc93e] -phys_addr_t -- --[[linux-4.4.1/phys_addr_t]] **参考 [#z2b56b9b] *実装 [#j3779f06] phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, dma_addr_t tbl_dma_addr, phys_addr_t orig_addr, size_t size, enum dma_data_direction dir) { unsigned long flags; phys_addr_t tlb_addr; unsigned int nslots, stride, index, wrap; int i; unsigned long mask; unsigned long offset_slots; unsigned long max_slots; - --[[linux-4.4.1/phys_addr_t]] if (no_iotlb_memory) panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer"); - --[[linux-4.4.1/no_iotlb_memory(global)]] --[[linux-4.4.1/panic()]] mask = dma_get_seg_boundary(hwdev); - --[[linux-4.4.1/dma_get_seg_boundary()]] tbl_dma_addr &= mask; offset_slots = ALIGN(tbl_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT; - --[[linux-4.4.1/ALIGN()]] /* * Carefully handle integer overflow which can occur when mask == ~0UL. */ max_slots = mask + 1 ? ALIGN(mask + 1, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT : 1UL << (BITS_PER_LONG - IO_TLB_SHIFT); /* * For mappings greater than a page, we limit the stride (and * hence alignment) to a page size. */ nslots = ALIGN(size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT; if (size > PAGE_SIZE) stride = (1 << (PAGE_SHIFT - IO_TLB_SHIFT)); else stride = 1; BUG_ON(!nslots); - --[[linux-4.4.1/BUG_ON()]] /* * Find suitable number of IO TLB entries size that will fit this * request and allocate a buffer from that IO TLB pool. */ spin_lock_irqsave(&io_tlb_lock, flags); index = ALIGN(io_tlb_index, stride); if (index >= io_tlb_nslabs) index = 0; wrap = index; - --[[linux-4.4.1/spin_lock_irqsave()]] --[[linux-4.4.1/io_tlb_lock(global)]] --[[linux-4.4.1/io_tlb_index(global)]] --[[linux-4.4.1/io_tlb_nslabs(global)]] do { while (iommu_is_span_boundary(index, nslots, offset_slots, max_slots)) { index += stride; if (index >= io_tlb_nslabs) index = 0; if (index == wrap) goto not_found; } - --[[linux-4.4.1/iommu_is_span_boundary()]] /* * If we find a slot that indicates we have 'nslots' number of * contiguous buffers, we allocate the buffers from that slot * and mark the entries as '0' indicating unavailable. */ if (io_tlb_list[index] >= nslots) { int count = 0; for (i = index; i < (int) (index + nslots); i++) io_tlb_list[i] = 0; for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE - 1) && io_tlb_list[i]; i--) io_tlb_list[i] = ++count; tlb_addr = io_tlb_start + (index << IO_TLB_SHIFT); - --[[linux-4.4.1/OFFSET()]] /* * Update the indices to avoid searching in the next * round. */ io_tlb_index = ((index + nslots) < io_tlb_nslabs ? (index + nslots) : 0); goto found; } index += stride; if (index >= io_tlb_nslabs) index = 0; } while (index != wrap); not_found: spin_unlock_irqrestore(&io_tlb_lock, flags); if (printk_ratelimit()) dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes)\n", size); - --[[linux-4.4.1/spin_unlock_irq_restore()]] --[[linux-4.4.1/printk_ratelimit()]] --[[linux-4.4.1/dev_warn()]] return SWIOTLB_MAP_ERROR; found: spin_unlock_irqrestore(&io_tlb_lock, flags); /* * Save away the mapping from the original address to the DMA address. * This is needed when we sync the memory. Then we sync the buffer if * needed. */ for (i = 0; i < nslots; i++) io_tlb_orig_addr[index+i] = orig_addr + (i << IO_TLB_SHIFT); if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) swiotlb_bounce(orig_addr, tlb_addr, size, DMA_TO_DEVICE); - --[[linux-4.4.1/swiotlb_bounce()]] return tlb_addr; } EXPORT_SYMBOL_GPL(swiotlb_tbl_map_single); - --[[linux-4.4.1/EXPORT_SYMBOL_GPL()]] *コメント [#ua881b49]
