参照元†
- struct device *hwdev
- dma_addr_t tbl_dma_addr
- phys_addr_t orig_addr
- size_t size
- enum dma_data_direction dir
返り値†
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;
if (no_iotlb_memory)
panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
mask = dma_get_seg_boundary(hwdev);
tbl_dma_addr &= mask;
offset_slots = ALIGN(tbl_dma_addr, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
/*
* 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);
/*
* 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;
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;
}
/*
* 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);
/*
* 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);
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);
return tlb_addr;
}
EXPORT_SYMBOL_GPL(swiotlb_tbl_map_single);
コメント†
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