text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * Dynamic DMA mapping support.
   *
   * This implementation is a fallback for platforms that do not support
   * I/O TLBs (aka DMA address translation hardware).
   * Copyright (C) 2000 Asit Mallick <Asit.K.Mallick@intel.com>
   * Copyright (C) 2000 Goutham Rao <goutham.rao@intel.com>
   * Copyright (C) 2000, 2003 Hewlett-Packard Co
   *	David Mosberger-Tang <davidm@hpl.hp.com>
   *
   * 03/05/07 davidm	Switch from PCI-DMA to generic device DMA API.
   * 00/12/13 davidm	Rename to swiotlb.c and add mark_clean() to avoid
   *			unnecessary i-cache flushing.
   * 04/07/.. ak		Better overflow handling. Assorted fixes.
   * 05/09/10 linville	Add support for syncing ranges, support syncing for
   *			DMA_BIDIRECTIONAL mappings, miscellaneous cleanup.
   * 08/12/11 beckyb	Add highmem support
   */
  
  #define pr_fmt(fmt) "software IO TLB: " fmt
  
  #include <linux/cache.h>
  #include <linux/dma-direct.h>
  #include <linux/dma-map-ops.h>
  #include <linux/mm.h>
  #include <linux/export.h>
  #include <linux/spinlock.h>
  #include <linux/string.h>
  #include <linux/swiotlb.h>
  #include <linux/pfn.h>
  #include <linux/types.h>
  #include <linux/ctype.h>
  #include <linux/highmem.h>
  #include <linux/gfp.h>
  #include <linux/scatterlist.h>
  #include <linux/mem_encrypt.h>
  #include <linux/set_memory.h>
  #ifdef CONFIG_DEBUG_FS
  #include <linux/debugfs.h>
  #endif
  
  #include <asm/io.h>
  #include <asm/dma.h>
  
  #include <linux/init.h>
  #include <linux/memblock.h>
  #include <linux/iommu-helper.h>
  
  #define CREATE_TRACE_POINTS
  #include <trace/events/swiotlb.h>
  
  #define OFFSET(val,align) ((unsigned long)	\
  	                   ( (val) & ( (align) - 1)))
  
  #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
  
  /*
   * Minimum IO TLB size to bother booting with.  Systems with mainly
   * 64bit capable cards will only lightly use the swiotlb.  If we can't
   * allocate a contiguous 1MB, we're probably in trouble anyway.
   */
  #define IO_TLB_MIN_SLABS ((1<<20) >> IO_TLB_SHIFT)
  
  enum swiotlb_force swiotlb_force;
  
  /*
   * Used to do a quick range check in swiotlb_tbl_unmap_single and
   * swiotlb_tbl_sync_single_*, to see if the memory was in fact allocated by this
   * API.
   */
  phys_addr_t io_tlb_start, io_tlb_end;
  
  /*
   * The number of IO TLB blocks (in groups of 64) between io_tlb_start and
   * io_tlb_end.  This is command line adjustable via setup_io_tlb_npages.
   */
  static unsigned long io_tlb_nslabs;
  
  /*
   * The number of used IO TLB block
   */
  static unsigned long io_tlb_used;
  
  /*
   * This is a free list describing the number of free entries available from
   * each index
   */
  static unsigned int *io_tlb_list;
  static unsigned int io_tlb_index;
  
  /*
   * Max segment that we can provide which (if pages are contingous) will
   * not be bounced (unless SWIOTLB_FORCE is set).
   */
  static unsigned int max_segment;
  
  /*
   * We need to save away the original address corresponding to a mapped entry
   * for the sync operations.
   */
  #define INVALID_PHYS_ADDR (~(phys_addr_t)0)
  static phys_addr_t *io_tlb_orig_addr;
  
  /*
   * Protect the above data structures in the map and unmap calls
   */
  static DEFINE_SPINLOCK(io_tlb_lock);
  
  static int late_alloc;
  
  static int __init
  setup_io_tlb_npages(char *str)
  {
  	if (isdigit(*str)) {
  		io_tlb_nslabs = simple_strtoul(str, &str, 0);
  		/* avoid tail segment of size < IO_TLB_SEGSIZE */
  		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
  	}
  	if (*str == ',')
  		++str;
  	if (!strcmp(str, "force")) {
  		swiotlb_force = SWIOTLB_FORCE;
  	} else if (!strcmp(str, "noforce")) {
  		swiotlb_force = SWIOTLB_NO_FORCE;
  		io_tlb_nslabs = 1;
  	}
  
  	return 0;
  }
  early_param("swiotlb", setup_io_tlb_npages);
  
  static bool no_iotlb_memory;
  
  unsigned long swiotlb_nr_tbl(void)
  {
  	return unlikely(no_iotlb_memory) ? 0 : io_tlb_nslabs;
  }
  EXPORT_SYMBOL_GPL(swiotlb_nr_tbl);
  
  unsigned int swiotlb_max_segment(void)
  {
  	return unlikely(no_iotlb_memory) ? 0 : max_segment;
  }
  EXPORT_SYMBOL_GPL(swiotlb_max_segment);
  
  void swiotlb_set_max_segment(unsigned int val)
  {
  	if (swiotlb_force == SWIOTLB_FORCE)
  		max_segment = 1;
  	else
  		max_segment = rounddown(val, PAGE_SIZE);
  }
  
  /* default to 64MB */
  #define IO_TLB_DEFAULT_SIZE (64UL<<20)
  unsigned long swiotlb_size_or_default(void)
  {
  	unsigned long size;
  
  	size = io_tlb_nslabs << IO_TLB_SHIFT;
  
  	return size ? size : (IO_TLB_DEFAULT_SIZE);
  }
  
  void swiotlb_print_info(void)
  {
  	unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT;
  
  	if (no_iotlb_memory) {
  		pr_warn("No low mem\n");
  		return;
  	}
  
  	pr_info("mapped [mem %pa-%pa] (%luMB)\n", &io_tlb_start, &io_tlb_end,
  	       bytes >> 20);
  }
  
  /*
   * Early SWIOTLB allocation may be too early to allow an architecture to
   * perform the desired operations.  This function allows the architecture to
   * call SWIOTLB when the operations are possible.  It needs to be called
   * before the SWIOTLB memory is used.
   */
  void __init swiotlb_update_mem_attributes(void)
  {
  	void *vaddr;
  	unsigned long bytes;
  
  	if (no_iotlb_memory || late_alloc)
  		return;
  
  	vaddr = phys_to_virt(io_tlb_start);
  	bytes = PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT);
  	set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
  	memset(vaddr, 0, bytes);
  }
  
  int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose)
  {
  	unsigned long i, bytes;
  	size_t alloc_size;
  
  	bytes = nslabs << IO_TLB_SHIFT;
  
  	io_tlb_nslabs = nslabs;
  	io_tlb_start = __pa(tlb);
  	io_tlb_end = io_tlb_start + bytes;
  
  	/*
  	 * Allocate and initialize the free list array.  This array is used
  	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
  	 * between io_tlb_start and io_tlb_end.
  	 */
  	alloc_size = PAGE_ALIGN(io_tlb_nslabs * sizeof(int));
  	io_tlb_list = memblock_alloc(alloc_size, PAGE_SIZE);
  	if (!io_tlb_list)
  		panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
  		      __func__, alloc_size, PAGE_SIZE);
  
  	alloc_size = PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t));
  	io_tlb_orig_addr = memblock_alloc(alloc_size, PAGE_SIZE);
  	if (!io_tlb_orig_addr)
  		panic("%s: Failed to allocate %zu bytes align=0x%lx\n",
  		      __func__, alloc_size, PAGE_SIZE);
  
  	for (i = 0; i < io_tlb_nslabs; i++) {
  		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
  	}
  	io_tlb_index = 0;
  	no_iotlb_memory = false;
  
  	if (verbose)
  		swiotlb_print_info();
  
  	swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);
  	return 0;
  }
  
  /*
   * Statically reserve bounce buffer space and initialize bounce buffer data
   * structures for the software IO TLB used to implement the DMA API.
   */
  void  __init
  swiotlb_init(int verbose)
  {
  	size_t default_size = IO_TLB_DEFAULT_SIZE;
  	unsigned char *vstart;
  	unsigned long bytes;
  
  	if (!io_tlb_nslabs) {
  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
  		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
  	}
  
  	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
  
  	/* Get IO TLB memory from the low pages */
  	vstart = memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE);
  	if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose))
  		return;
  
  	if (io_tlb_start) {
  		memblock_free_early(io_tlb_start,
  				    PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
  		io_tlb_start = 0;
  	}
  	pr_warn("Cannot allocate buffer");
  	no_iotlb_memory = true;
  }
  
  /*
   * Systems with larger DMA zones (those that don't support ISA) can
   * initialize the swiotlb later using the slab allocator if needed.
   * This should be just like above, but with some error catching.
   */
  int
  swiotlb_late_init_with_default_size(size_t default_size)
  {
  	unsigned long bytes, req_nslabs = io_tlb_nslabs;
  	unsigned char *vstart = NULL;
  	unsigned int order;
  	int rc = 0;
  
  	if (!io_tlb_nslabs) {
  		io_tlb_nslabs = (default_size >> IO_TLB_SHIFT);
  		io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
  	}
  
  	/*
  	 * Get IO TLB memory from the low pages
  	 */
  	order = get_order(io_tlb_nslabs << IO_TLB_SHIFT);
  	io_tlb_nslabs = SLABS_PER_PAGE << order;
  	bytes = io_tlb_nslabs << IO_TLB_SHIFT;
  
  	while ((SLABS_PER_PAGE << order) > IO_TLB_MIN_SLABS) {
  		vstart = (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN,
  						  order);
  		if (vstart)
  			break;
  		order--;
  	}
  
  	if (!vstart) {
  		io_tlb_nslabs = req_nslabs;
  		return -ENOMEM;
  	}
  	if (order != get_order(bytes)) {
  		pr_warn("only able to allocate %ld MB\n",
  			(PAGE_SIZE << order) >> 20);
  		io_tlb_nslabs = SLABS_PER_PAGE << order;
  	}
  	rc = swiotlb_late_init_with_tbl(vstart, io_tlb_nslabs);
  	if (rc)
  		free_pages((unsigned long)vstart, order);
  
  	return rc;
  }
  
  static void swiotlb_cleanup(void)
  {
  	io_tlb_end = 0;
  	io_tlb_start = 0;
  	io_tlb_nslabs = 0;
  	max_segment = 0;
  }
  
  int
  swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
  {
  	unsigned long i, bytes;
  
  	bytes = nslabs << IO_TLB_SHIFT;
  
  	io_tlb_nslabs = nslabs;
  	io_tlb_start = virt_to_phys(tlb);
  	io_tlb_end = io_tlb_start + bytes;
  
  	set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
  	memset(tlb, 0, bytes);
  
  	/*
  	 * Allocate and initialize the free list array.  This array is used
  	 * to find contiguous free memory regions of size up to IO_TLB_SEGSIZE
  	 * between io_tlb_start and io_tlb_end.
  	 */
  	io_tlb_list = (unsigned int *)__get_free_pages(GFP_KERNEL,
  	                              get_order(io_tlb_nslabs * sizeof(int)));
  	if (!io_tlb_list)
  		goto cleanup3;
  
  	io_tlb_orig_addr = (phys_addr_t *)
  		__get_free_pages(GFP_KERNEL,
  				 get_order(io_tlb_nslabs *
  					   sizeof(phys_addr_t)));
  	if (!io_tlb_orig_addr)
  		goto cleanup4;
  
  	for (i = 0; i < io_tlb_nslabs; i++) {
  		io_tlb_list[i] = IO_TLB_SEGSIZE - OFFSET(i, IO_TLB_SEGSIZE);
  		io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
  	}
  	io_tlb_index = 0;
  	no_iotlb_memory = false;
  
  	swiotlb_print_info();
  
  	late_alloc = 1;
  
  	swiotlb_set_max_segment(io_tlb_nslabs << IO_TLB_SHIFT);
  
  	return 0;
  
  cleanup4:
  	free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
  	                                                 sizeof(int)));
  	io_tlb_list = NULL;
  cleanup3:
  	swiotlb_cleanup();
  	return -ENOMEM;
  }
  
  void __init swiotlb_exit(void)
  {
  	if (!io_tlb_orig_addr)
  		return;
  
  	if (late_alloc) {
  		free_pages((unsigned long)io_tlb_orig_addr,
  			   get_order(io_tlb_nslabs * sizeof(phys_addr_t)));
  		free_pages((unsigned long)io_tlb_list, get_order(io_tlb_nslabs *
  								 sizeof(int)));
  		free_pages((unsigned long)phys_to_virt(io_tlb_start),
  			   get_order(io_tlb_nslabs << IO_TLB_SHIFT));
  	} else {
  		memblock_free_late(__pa(io_tlb_orig_addr),
  				   PAGE_ALIGN(io_tlb_nslabs * sizeof(phys_addr_t)));
  		memblock_free_late(__pa(io_tlb_list),
  				   PAGE_ALIGN(io_tlb_nslabs * sizeof(int)));
  		memblock_free_late(io_tlb_start,
  				   PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
  	}
  	swiotlb_cleanup();
  }
  
  /*
   * Bounce: copy the swiotlb buffer from or back to the original dma location
   */
  static void swiotlb_bounce(phys_addr_t orig_addr, phys_addr_t tlb_addr,
  			   size_t size, enum dma_data_direction dir)
  {
  	unsigned long pfn = PFN_DOWN(orig_addr);
  	unsigned char *vaddr = phys_to_virt(tlb_addr);
  
  	if (PageHighMem(pfn_to_page(pfn))) {
  		/* The buffer does not have a mapping.  Map it in and copy */
  		unsigned int offset = orig_addr & ~PAGE_MASK;
  		char *buffer;
  		unsigned int sz = 0;
  		unsigned long flags;
  
  		while (size) {
  			sz = min_t(size_t, PAGE_SIZE - offset, size);
  
  			local_irq_save(flags);
  			buffer = kmap_atomic(pfn_to_page(pfn));
  			if (dir == DMA_TO_DEVICE)
  				memcpy(vaddr, buffer + offset, sz);
  			else
  				memcpy(buffer + offset, vaddr, sz);
  			kunmap_atomic(buffer);
  			local_irq_restore(flags);
  
  			size -= sz;
  			pfn++;
  			vaddr += sz;
  			offset = 0;
  		}
  	} else if (dir == DMA_TO_DEVICE) {
  		memcpy(vaddr, phys_to_virt(orig_addr), size);
  	} else {
  		memcpy(phys_to_virt(orig_addr), vaddr, size);
  	}
  }
  
  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)
  {
  	dma_addr_t tbl_dma_addr = phys_to_dma_unencrypted(hwdev, io_tlb_start);
  	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;
  	unsigned long tmp_io_tlb_used;
  
  	if (no_iotlb_memory)
  		panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer");
  
  	if (mem_encrypt_active())
  		pr_warn_once("Memory encryption is active and system is using DMA bounce buffers\n");
  
  	if (mapping_size > alloc_size) {
  		dev_warn_once(hwdev, "Invalid sizes (mapping: %zd bytes, alloc: %zd bytes)",
  			      mapping_size, alloc_size);
  		return (phys_addr_t)DMA_MAPPING_ERROR;
  	}
  
  	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 or equal to a page, we limit the stride
  	 * (and hence alignment) to a page size.
  	 */
  	nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
  	if (alloc_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);
  
  	if (unlikely(nslots > io_tlb_nslabs - io_tlb_used))
  		goto not_found;
  
  	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:
  	tmp_io_tlb_used = io_tlb_used;
  
  	spin_unlock_irqrestore(&io_tlb_lock, flags);
  	if (!(attrs & DMA_ATTR_NO_WARN) && printk_ratelimit())
  		dev_warn(hwdev, "swiotlb buffer is full (sz: %zd bytes), total %lu (slots), used %lu (slots)\n",
  			 alloc_size, io_tlb_nslabs, tmp_io_tlb_used);
  	return (phys_addr_t)DMA_MAPPING_ERROR;
  found:
  	io_tlb_used += nslots;
  	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 (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
  	    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
  		swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_TO_DEVICE);
  
  	return tlb_addr;
  }
  
  /*
   * tlb_addr is the physical address of the bounce buffer to unmap.
   */
  void swiotlb_tbl_unmap_single(struct device *hwdev, phys_addr_t tlb_addr,
  			      size_t mapping_size, size_t alloc_size,
  			      enum dma_data_direction dir, unsigned long attrs)
  {
  	unsigned long flags;
  	int i, count, nslots = ALIGN(alloc_size, 1 << IO_TLB_SHIFT) >> IO_TLB_SHIFT;
  	int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
  	phys_addr_t orig_addr = io_tlb_orig_addr[index];
  
  	/*
  	 * First, sync the memory before unmapping the entry
  	 */
  	if (orig_addr != INVALID_PHYS_ADDR &&
  	    !(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
  	    ((dir == DMA_FROM_DEVICE) || (dir == DMA_BIDIRECTIONAL)))
  		swiotlb_bounce(orig_addr, tlb_addr, mapping_size, DMA_FROM_DEVICE);
  
  	/*
  	 * Return the buffer to the free list by setting the corresponding
  	 * entries to indicate the number of contiguous entries available.
  	 * While returning the entries to the free list, we merge the entries
  	 * with slots below and above the pool being returned.
  	 */
  	spin_lock_irqsave(&io_tlb_lock, flags);
  	{
  		count = ((index + nslots) < ALIGN(index + 1, IO_TLB_SEGSIZE) ?
  			 io_tlb_list[index + nslots] : 0);
  		/*
  		 * Step 1: return the slots to the free list, merging the
  		 * slots with superceeding slots
  		 */
  		for (i = index + nslots - 1; i >= index; i--) {
  			io_tlb_list[i] = ++count;
  			io_tlb_orig_addr[i] = INVALID_PHYS_ADDR;
  		}
  		/*
  		 * Step 2: merge the returned slots with the preceding slots,
  		 * if available (non zero)
  		 */
  		for (i = index - 1; (OFFSET(i, IO_TLB_SEGSIZE) != IO_TLB_SEGSIZE -1) && io_tlb_list[i]; i--)
  			io_tlb_list[i] = ++count;
  
  		io_tlb_used -= nslots;
  	}
  	spin_unlock_irqrestore(&io_tlb_lock, flags);
  }
  
  void swiotlb_tbl_sync_single(struct device *hwdev, phys_addr_t tlb_addr,
  			     size_t size, enum dma_data_direction dir,
  			     enum dma_sync_target target)
  {
  	int index = (tlb_addr - io_tlb_start) >> IO_TLB_SHIFT;
  	phys_addr_t orig_addr = io_tlb_orig_addr[index];
  
  	if (orig_addr == INVALID_PHYS_ADDR)
  		return;
  	orig_addr += (unsigned long)tlb_addr & ((1 << IO_TLB_SHIFT) - 1);
  
  	switch (target) {
  	case SYNC_FOR_CPU:
  		if (likely(dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL))
  			swiotlb_bounce(orig_addr, tlb_addr,
  				       size, DMA_FROM_DEVICE);
  		else
  			BUG_ON(dir != DMA_TO_DEVICE);
  		break;
  	case SYNC_FOR_DEVICE:
  		if (likely(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
  			swiotlb_bounce(orig_addr, tlb_addr,
  				       size, DMA_TO_DEVICE);
  		else
  			BUG_ON(dir != DMA_FROM_DEVICE);
  		break;
  	default:
  		BUG();
  	}
  }
  
  /*
   * Create a swiotlb mapping for the buffer at @paddr, and in case of DMAing
   * to the device copy the data into it as well.
   */
  dma_addr_t swiotlb_map(struct device *dev, phys_addr_t paddr, size_t size,
  		enum dma_data_direction dir, unsigned long attrs)
  {
  	phys_addr_t swiotlb_addr;
  	dma_addr_t dma_addr;
  
  	trace_swiotlb_bounced(dev, phys_to_dma(dev, paddr), size,
  			      swiotlb_force);
  
  	swiotlb_addr = swiotlb_tbl_map_single(dev, paddr, size, size, dir,
  			attrs);
  	if (swiotlb_addr == (phys_addr_t)DMA_MAPPING_ERROR)
  		return DMA_MAPPING_ERROR;
  
  	/* Ensure that the address returned is DMA'ble */
  	dma_addr = phys_to_dma_unencrypted(dev, swiotlb_addr);
  	if (unlikely(!dma_capable(dev, dma_addr, size, true))) {
  		swiotlb_tbl_unmap_single(dev, swiotlb_addr, size, size, dir,
  			attrs | DMA_ATTR_SKIP_CPU_SYNC);
  		dev_WARN_ONCE(dev, 1,
  			"swiotlb addr %pad+%zu overflow (mask %llx, bus limit %llx).\n",
  			&dma_addr, size, *dev->dma_mask, dev->bus_dma_limit);
  		return DMA_MAPPING_ERROR;
  	}
  
  	if (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
  		arch_sync_dma_for_device(swiotlb_addr, size, dir);
  	return dma_addr;
  }
  
  size_t swiotlb_max_mapping_size(struct device *dev)
  {
  	return ((size_t)1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
  }
  
  bool is_swiotlb_active(void)
  {
  	/*
  	 * When SWIOTLB is initialized, even if io_tlb_start points to physical
  	 * address zero, io_tlb_end surely doesn't.
  	 */
  	return io_tlb_end != 0;
  }
  
  #ifdef CONFIG_DEBUG_FS
  
  static int __init swiotlb_create_debugfs(void)
  {
  	struct dentry *root;
  
  	root = debugfs_create_dir("swiotlb", NULL);
  	debugfs_create_ulong("io_tlb_nslabs", 0400, root, &io_tlb_nslabs);
  	debugfs_create_ulong("io_tlb_used", 0400, root, &io_tlb_used);
  	return 0;
  }
  
  late_initcall(swiotlb_create_debugfs);
  
  #endif
  