text: /*
   * Copyright © 2006-2009, Intel Corporation.
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License along with
   * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
   * Place - Suite 330, Boston, MA 02111-1307 USA.
   *
   * Author: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
   */
  
  #include <linux/iova.h>
  #include <linux/slab.h>
  
  static struct kmem_cache *iommu_iova_cache;
  
  int iommu_iova_cache_init(void)
  {
  	int ret = 0;
  
  	iommu_iova_cache = kmem_cache_create("iommu_iova",
  					 sizeof(struct iova),
  					 0,
  					 SLAB_HWCACHE_ALIGN,
  					 NULL);
  	if (!iommu_iova_cache) {
  		pr_err("Couldn't create iova cache\n");
  		ret = -ENOMEM;
  	}
  
  	return ret;
  }
  
  void iommu_iova_cache_destroy(void)
  {
  	kmem_cache_destroy(iommu_iova_cache);
  }
  
  struct iova *alloc_iova_mem(void)
  {
  	return kmem_cache_alloc(iommu_iova_cache, GFP_ATOMIC);
  }
  
  void free_iova_mem(struct iova *iova)
  {
  	kmem_cache_free(iommu_iova_cache, iova);
  }
  
  void
  init_iova_domain(struct iova_domain *iovad, unsigned long granule,
  	unsigned long start_pfn, unsigned long pfn_32bit)
  {
  	/*
  	 * IOVA granularity will normally be equal to the smallest
  	 * supported IOMMU page size; both *must* be capable of
  	 * representing individual CPU pages exactly.
  	 */
  	BUG_ON((granule > PAGE_SIZE) || !is_power_of_2(granule));
  
  	spin_lock_init(&iovad->iova_rbtree_lock);
  	iovad->rbroot = RB_ROOT;
  	iovad->cached32_node = NULL;
  	iovad->granule = granule;
  	iovad->start_pfn = start_pfn;
  	iovad->dma_32bit_pfn = pfn_32bit;
  }
  
  static struct rb_node *
  __get_cached_rbnode(struct iova_domain *iovad, unsigned long *limit_pfn)
  {
  	if ((*limit_pfn != iovad->dma_32bit_pfn) ||
  		(iovad->cached32_node == NULL))
  		return rb_last(&iovad->rbroot);
  	else {
  		struct rb_node *prev_node = rb_prev(iovad->cached32_node);
  		struct iova *curr_iova =
  			container_of(iovad->cached32_node, struct iova, node);
  		*limit_pfn = curr_iova->pfn_lo - 1;
  		return prev_node;
  	}
  }
  
  static void
  __cached_rbnode_insert_update(struct iova_domain *iovad,
  	unsigned long limit_pfn, struct iova *new)
  {
  	if (limit_pfn != iovad->dma_32bit_pfn)
  		return;
  	iovad->cached32_node = &new->node;
  }
  
  static void
  __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
  {
  	struct iova *cached_iova;
  	struct rb_node *curr;
  
  	if (!iovad->cached32_node)
  		return;
  	curr = iovad->cached32_node;
  	cached_iova = container_of(curr, struct iova, node);
  
  	if (free->pfn_lo >= cached_iova->pfn_lo) {
  		struct rb_node *node = rb_next(&free->node);
  		struct iova *iova = container_of(node, struct iova, node);
  
  		/* only cache if it's below 32bit pfn */
  		if (node && iova->pfn_lo < iovad->dma_32bit_pfn)
  			iovad->cached32_node = node;
  		else
  			iovad->cached32_node = NULL;
  	}
  }
  
  /* Computes the padding size required, to make the
   * the start address naturally aligned on its size
   */
  static int
  iova_get_pad_size(int size, unsigned int limit_pfn)
  {
  	unsigned int pad_size = 0;
  	unsigned int order = ilog2(size);
  
  	if (order)
  		pad_size = (limit_pfn + 1) % (1 << order);
  
  	return pad_size;
  }
  
  static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
  		unsigned long size, unsigned long limit_pfn,
  			struct iova *new, bool size_aligned)
  {
  	struct rb_node *prev, *curr = NULL;
  	unsigned long flags;
  	unsigned long saved_pfn;
  	unsigned int pad_size = 0;
  
  	/* Walk the tree backwards */
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	saved_pfn = limit_pfn;
  	curr = __get_cached_rbnode(iovad, &limit_pfn);
  	prev = curr;
  	while (curr) {
  		struct iova *curr_iova = container_of(curr, struct iova, node);
  
  		if (limit_pfn < curr_iova->pfn_lo)
  			goto move_left;
  		else if (limit_pfn < curr_iova->pfn_hi)
  			goto adjust_limit_pfn;
  		else {
  			if (size_aligned)
  				pad_size = iova_get_pad_size(size, limit_pfn);
  			if ((curr_iova->pfn_hi + size + pad_size) <= limit_pfn)
  				break;	/* found a free slot */
  		}
  adjust_limit_pfn:
  		limit_pfn = curr_iova->pfn_lo - 1;
  move_left:
  		prev = curr;
  		curr = rb_prev(curr);
  	}
  
  	if (!curr) {
  		if (size_aligned)
  			pad_size = iova_get_pad_size(size, limit_pfn);
  		if ((iovad->start_pfn + size + pad_size) > limit_pfn) {
  			spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  			return -ENOMEM;
  		}
  	}
  
  	/* pfn_lo will point to size aligned address if size_aligned is set */
  	new->pfn_lo = limit_pfn - (size + pad_size) + 1;
  	new->pfn_hi = new->pfn_lo + size - 1;
  
  	/* Insert the new_iova into domain rbtree by holding writer lock */
  	/* Add new node and rebalance tree. */
  	{
  		struct rb_node **entry, *parent = NULL;
  
  		/* If we have 'prev', it's a valid place to start the
  		   insertion. Otherwise, start from the root. */
  		if (prev)
  			entry = &prev;
  		else
  			entry = &iovad->rbroot.rb_node;
  
  		/* Figure out where to put new node */
  		while (*entry) {
  			struct iova *this = container_of(*entry,
  							struct iova, node);
  			parent = *entry;
  
  			if (new->pfn_lo < this->pfn_lo)
  				entry = &((*entry)->rb_left);
  			else if (new->pfn_lo > this->pfn_lo)
  				entry = &((*entry)->rb_right);
  			else
  				BUG(); /* this should not happen */
  		}
  
  		/* Add new node and rebalance tree. */
  		rb_link_node(&new->node, parent, entry);
  		rb_insert_color(&new->node, &iovad->rbroot);
  	}
  	__cached_rbnode_insert_update(iovad, saved_pfn, new);
  
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  
  
  	return 0;
  }
  
  static void
  iova_insert_rbtree(struct rb_root *root, struct iova *iova)
  {
  	struct rb_node **new = &(root->rb_node), *parent = NULL;
  	/* Figure out where to put new node */
  	while (*new) {
  		struct iova *this = container_of(*new, struct iova, node);
  
  		parent = *new;
  
  		if (iova->pfn_lo < this->pfn_lo)
  			new = &((*new)->rb_left);
  		else if (iova->pfn_lo > this->pfn_lo)
  			new = &((*new)->rb_right);
  		else
  			BUG(); /* this should not happen */
  	}
  	/* Add new node and rebalance tree. */
  	rb_link_node(&iova->node, parent, new);
  	rb_insert_color(&iova->node, root);
  }
  
  /**
   * alloc_iova - allocates an iova
   * @iovad: - iova domain in question
   * @size: - size of page frames to allocate
   * @limit_pfn: - max limit address
   * @size_aligned: - set if size_aligned address range is required
   * This function allocates an iova in the range iovad->start_pfn to limit_pfn,
   * searching top-down from limit_pfn to iovad->start_pfn. If the size_aligned
   * flag is set then the allocated address iova->pfn_lo will be naturally
   * aligned on roundup_power_of_two(size).
   */
  struct iova *
  alloc_iova(struct iova_domain *iovad, unsigned long size,
  	unsigned long limit_pfn,
  	bool size_aligned)
  {
  	struct iova *new_iova;
  	int ret;
  
  	new_iova = alloc_iova_mem();
  	if (!new_iova)
  		return NULL;
  
  	/* If size aligned is set then round the size to
  	 * to next power of two.
  	 */
  	if (size_aligned)
  		size = __roundup_pow_of_two(size);
  
  	ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn,
  			new_iova, size_aligned);
  
  	if (ret) {
  		free_iova_mem(new_iova);
  		return NULL;
  	}
  
  	return new_iova;
  }
  
  /**
   * find_iova - find's an iova for a given pfn
   * @iovad: - iova domain in question.
   * @pfn: - page frame number
   * This function finds and returns an iova belonging to the
   * given doamin which matches the given pfn.
   */
  struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
  {
  	unsigned long flags;
  	struct rb_node *node;
  
  	/* Take the lock so that no other thread is manipulating the rbtree */
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	node = iovad->rbroot.rb_node;
  	while (node) {
  		struct iova *iova = container_of(node, struct iova, node);
  
  		/* If pfn falls within iova's range, return iova */
  		if ((pfn >= iova->pfn_lo) && (pfn <= iova->pfn_hi)) {
  			spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  			/* We are not holding the lock while this iova
  			 * is referenced by the caller as the same thread
  			 * which called this function also calls __free_iova()
  			 * and it is by design that only one thread can possibly
  			 * reference a particular iova and hence no conflict.
  			 */
  			return iova;
  		}
  
  		if (pfn < iova->pfn_lo)
  			node = node->rb_left;
  		else if (pfn > iova->pfn_lo)
  			node = node->rb_right;
  	}
  
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  	return NULL;
  }
  
  /**
   * __free_iova - frees the given iova
   * @iovad: iova domain in question.
   * @iova: iova in question.
   * Frees the given iova belonging to the giving domain
   */
  void
  __free_iova(struct iova_domain *iovad, struct iova *iova)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	__cached_rbnode_delete_update(iovad, iova);
  	rb_erase(&iova->node, &iovad->rbroot);
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  	free_iova_mem(iova);
  }
  
  /**
   * free_iova - finds and frees the iova for a given pfn
   * @iovad: - iova domain in question.
   * @pfn: - pfn that is allocated previously
   * This functions finds an iova for a given pfn and then
   * frees the iova from that domain.
   */
  void
  free_iova(struct iova_domain *iovad, unsigned long pfn)
  {
  	struct iova *iova = find_iova(iovad, pfn);
  
  	if (iova)
  		__free_iova(iovad, iova);
  
  }
  
  /**
   * put_iova_domain - destroys the iova doamin
   * @iovad: - iova domain in question.
   * All the iova's in that domain are destroyed.
   */
  void put_iova_domain(struct iova_domain *iovad)
  {
  	struct rb_node *node;
  	unsigned long flags;
  
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	node = rb_first(&iovad->rbroot);
  	while (node) {
  		struct iova *iova = container_of(node, struct iova, node);
  
  		rb_erase(node, &iovad->rbroot);
  		free_iova_mem(iova);
  		node = rb_first(&iovad->rbroot);
  	}
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  }
  
  static int
  __is_range_overlap(struct rb_node *node,
  	unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	struct iova *iova = container_of(node, struct iova, node);
  
  	if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
  		return 1;
  	return 0;
  }
  
  static inline struct iova *
  alloc_and_init_iova(unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	struct iova *iova;
  
  	iova = alloc_iova_mem();
  	if (iova) {
  		iova->pfn_lo = pfn_lo;
  		iova->pfn_hi = pfn_hi;
  	}
  
  	return iova;
  }
  
  static struct iova *
  __insert_new_range(struct iova_domain *iovad,
  	unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	struct iova *iova;
  
  	iova = alloc_and_init_iova(pfn_lo, pfn_hi);
  	if (iova)
  		iova_insert_rbtree(&iovad->rbroot, iova);
  
  	return iova;
  }
  
  static void
  __adjust_overlap_range(struct iova *iova,
  	unsigned long *pfn_lo, unsigned long *pfn_hi)
  {
  	if (*pfn_lo < iova->pfn_lo)
  		iova->pfn_lo = *pfn_lo;
  	if (*pfn_hi > iova->pfn_hi)
  		*pfn_lo = iova->pfn_hi + 1;
  }
  
  /**
   * reserve_iova - reserves an iova in the given range
   * @iovad: - iova domain pointer
   * @pfn_lo: - lower page frame address
   * @pfn_hi:- higher pfn adderss
   * This function allocates reserves the address range from pfn_lo to pfn_hi so
   * that this address is not dished out as part of alloc_iova.
   */
  struct iova *
  reserve_iova(struct iova_domain *iovad,
  	unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	struct rb_node *node;
  	unsigned long flags;
  	struct iova *iova;
  	unsigned int overlap = 0;
  
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
  		if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
  			iova = container_of(node, struct iova, node);
  			__adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
  			if ((pfn_lo >= iova->pfn_lo) &&
  				(pfn_hi <= iova->pfn_hi))
  				goto finish;
  			overlap = 1;
  
  		} else if (overlap)
  				break;
  	}
  
  	/* We are here either because this is the first reserver node
  	 * or need to insert remaining non overlap addr range
  	 */
  	iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
  finish:
  
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  	return iova;
  }
  
  /**
   * copy_reserved_iova - copies the reserved between domains
   * @from: - source doamin from where to copy
   * @to: - destination domin where to copy
   * This function copies reserved iova's from one doamin to
   * other.
   */
  void
  copy_reserved_iova(struct iova_domain *from, struct iova_domain *to)
  {
  	unsigned long flags;
  	struct rb_node *node;
  
  	spin_lock_irqsave(&from->iova_rbtree_lock, flags);
  	for (node = rb_first(&from->rbroot); node; node = rb_next(node)) {
  		struct iova *iova = container_of(node, struct iova, node);
  		struct iova *new_iova;
  
  		new_iova = reserve_iova(to, iova->pfn_lo, iova->pfn_hi);
  		if (!new_iova)
  			printk(KERN_ERR "Reserve iova range %lx@%lx failed\n",
  				iova->pfn_lo, iova->pfn_lo);
  	}
  	spin_unlock_irqrestore(&from->iova_rbtree_lock, flags);
  }
  
  struct iova *
  split_and_remove_iova(struct iova_domain *iovad, struct iova *iova,
  		      unsigned long pfn_lo, unsigned long pfn_hi)
  {
  	unsigned long flags;
  	struct iova *prev = NULL, *next = NULL;
  
  	spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
  	if (iova->pfn_lo < pfn_lo) {
  		prev = alloc_and_init_iova(iova->pfn_lo, pfn_lo - 1);
  		if (prev == NULL)
  			goto error;
  	}
  	if (iova->pfn_hi > pfn_hi) {
  		next = alloc_and_init_iova(pfn_hi + 1, iova->pfn_hi);
  		if (next == NULL)
  			goto error;
  	}
  
  	__cached_rbnode_delete_update(iovad, iova);
  	rb_erase(&iova->node, &iovad->rbroot);
  
  	if (prev) {
  		iova_insert_rbtree(&iovad->rbroot, prev);
  		iova->pfn_lo = pfn_lo;
  	}
  	if (next) {
  		iova_insert_rbtree(&iovad->rbroot, next);
  		iova->pfn_hi = pfn_hi;
  	}
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  
  	return iova;
  
  error:
  	spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
  	if (prev)
  		free_iova_mem(prev);
  	return NULL;
  }
  