> +#ifdef CONFIG_SWIOTLB
> + if (unlikely(dev->dma_io_tlb_mem))
> + return swiotlb_alloc(dev, size, dma_handle, attrs);
> +#endif
Another place where the dma_io_tlb_mem is useful to avoid the ifdef.
> -phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, phys_addr_t orig_addr,
> - size_t mapping_size, size_t alloc_size,
> - enum dma_data_direction dir, unsigned long attrs)
> +static int swiotlb_tbl_find_free_region(struct device *hwdev,
> + dma_addr_t tbl_dma_addr,
> + size_t alloc_size,
> + unsigned long attrs)
> +static void swiotlb_tbl_release_region(struct device *hwdev, int index,
> + size_t size)
This refactoring should be another prep patch.
> +void *swiotlb_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
> + unsigned long attrs)
I'd rather have the names convey there are for the per-device bounce
buffer in some form.
> + struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
While we're at it I wonder if the io_tlb is something we could change
while we're at it. Maybe replace io_tlb_mem with struct swiotlb
and rename the field in struct device to dev_swiotlb?
> + int index;
> + void *vaddr;
> + phys_addr_t tlb_addr;
> +
> + size = PAGE_ALIGN(size);
> + index = swiotlb_tbl_find_free_region(dev, mem->start, size, attrs);
> + if (index < 0)
> + return NULL;
> +
> + tlb_addr = mem->start + (index << IO_TLB_SHIFT);
> + *dma_handle = phys_to_dma_unencrypted(dev, tlb_addr);
> +
> + if (!dev_is_dma_coherent(dev)) {
> + unsigned long pfn = PFN_DOWN(tlb_addr);
> +
> + /* remove any dirty cache lines on the kernel alias */
> + arch_dma_prep_coherent(pfn_to_page(pfn), size);
Can we hook in somewhat lower level in the dma-direct code so that all
the remapping in dma-direct can be reused instead of duplicated? That
also becomes important if we want to use non-remapping uncached support,
e.g. on mips or x86, or the direct changing of the attributes that Will
planned to look into for arm64.
