Linux 2.6.34-rc3
[pohmelfs.git] / drivers / pci / iova.c
blob7914951ef29a9bab0b4bf4371f6d396503abd4ac
1 /*
2 * Copyright © 2006-2009, Intel Corporation.
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms and conditions of the GNU General Public License,
6 * version 2, as published by the Free Software Foundation.
8 * This program is distributed in the hope it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
13 * You should have received a copy of the GNU General Public License along with
14 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
15 * Place - Suite 330, Boston, MA 02111-1307 USA.
17 * Author: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
20 #include <linux/iova.h>
22 void
23 init_iova_domain(struct iova_domain *iovad, unsigned long pfn_32bit)
25 spin_lock_init(&iovad->iova_rbtree_lock);
26 iovad->rbroot = RB_ROOT;
27 iovad->cached32_node = NULL;
28 iovad->dma_32bit_pfn = pfn_32bit;
31 static struct rb_node *
32 __get_cached_rbnode(struct iova_domain *iovad, unsigned long *limit_pfn)
34 if ((*limit_pfn != iovad->dma_32bit_pfn) ||
35 (iovad->cached32_node == NULL))
36 return rb_last(&iovad->rbroot);
37 else {
38 struct rb_node *prev_node = rb_prev(iovad->cached32_node);
39 struct iova *curr_iova =
40 container_of(iovad->cached32_node, struct iova, node);
41 *limit_pfn = curr_iova->pfn_lo - 1;
42 return prev_node;
46 static void
47 __cached_rbnode_insert_update(struct iova_domain *iovad,
48 unsigned long limit_pfn, struct iova *new)
50 if (limit_pfn != iovad->dma_32bit_pfn)
51 return;
52 iovad->cached32_node = &new->node;
55 static void
56 __cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
58 struct iova *cached_iova;
59 struct rb_node *curr;
61 if (!iovad->cached32_node)
62 return;
63 curr = iovad->cached32_node;
64 cached_iova = container_of(curr, struct iova, node);
66 if (free->pfn_lo >= cached_iova->pfn_lo)
67 iovad->cached32_node = rb_next(&free->node);
70 /* Computes the padding size required, to make the
71 * the start address naturally aligned on its size
73 static int
74 iova_get_pad_size(int size, unsigned int limit_pfn)
76 unsigned int pad_size = 0;
77 unsigned int order = ilog2(size);
79 if (order)
80 pad_size = (limit_pfn + 1) % (1 << order);
82 return pad_size;
85 static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
86 unsigned long size, unsigned long limit_pfn,
87 struct iova *new, bool size_aligned)
89 struct rb_node *prev, *curr = NULL;
90 unsigned long flags;
91 unsigned long saved_pfn;
92 unsigned int pad_size = 0;
94 /* Walk the tree backwards */
95 spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
96 saved_pfn = limit_pfn;
97 curr = __get_cached_rbnode(iovad, &limit_pfn);
98 prev = curr;
99 while (curr) {
100 struct iova *curr_iova = container_of(curr, struct iova, node);
102 if (limit_pfn < curr_iova->pfn_lo)
103 goto move_left;
104 else if (limit_pfn < curr_iova->pfn_hi)
105 goto adjust_limit_pfn;
106 else {
107 if (size_aligned)
108 pad_size = iova_get_pad_size(size, limit_pfn);
109 if ((curr_iova->pfn_hi + size + pad_size) <= limit_pfn)
110 break; /* found a free slot */
112 adjust_limit_pfn:
113 limit_pfn = curr_iova->pfn_lo - 1;
114 move_left:
115 prev = curr;
116 curr = rb_prev(curr);
119 if (!curr) {
120 if (size_aligned)
121 pad_size = iova_get_pad_size(size, limit_pfn);
122 if ((IOVA_START_PFN + size + pad_size) > limit_pfn) {
123 spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
124 return -ENOMEM;
128 /* pfn_lo will point to size aligned address if size_aligned is set */
129 new->pfn_lo = limit_pfn - (size + pad_size) + 1;
130 new->pfn_hi = new->pfn_lo + size - 1;
132 /* Insert the new_iova into domain rbtree by holding writer lock */
133 /* Add new node and rebalance tree. */
135 struct rb_node **entry, *parent = NULL;
137 /* If we have 'prev', it's a valid place to start the
138 insertion. Otherwise, start from the root. */
139 if (prev)
140 entry = &prev;
141 else
142 entry = &iovad->rbroot.rb_node;
144 /* Figure out where to put new node */
145 while (*entry) {
146 struct iova *this = container_of(*entry,
147 struct iova, node);
148 parent = *entry;
150 if (new->pfn_lo < this->pfn_lo)
151 entry = &((*entry)->rb_left);
152 else if (new->pfn_lo > this->pfn_lo)
153 entry = &((*entry)->rb_right);
154 else
155 BUG(); /* this should not happen */
158 /* Add new node and rebalance tree. */
159 rb_link_node(&new->node, parent, entry);
160 rb_insert_color(&new->node, &iovad->rbroot);
162 __cached_rbnode_insert_update(iovad, saved_pfn, new);
164 spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
167 return 0;
170 static void
171 iova_insert_rbtree(struct rb_root *root, struct iova *iova)
173 struct rb_node **new = &(root->rb_node), *parent = NULL;
174 /* Figure out where to put new node */
175 while (*new) {
176 struct iova *this = container_of(*new, struct iova, node);
177 parent = *new;
179 if (iova->pfn_lo < this->pfn_lo)
180 new = &((*new)->rb_left);
181 else if (iova->pfn_lo > this->pfn_lo)
182 new = &((*new)->rb_right);
183 else
184 BUG(); /* this should not happen */
186 /* Add new node and rebalance tree. */
187 rb_link_node(&iova->node, parent, new);
188 rb_insert_color(&iova->node, root);
192 * alloc_iova - allocates an iova
193 * @iovad - iova domain in question
194 * @size - size of page frames to allocate
195 * @limit_pfn - max limit address
196 * @size_aligned - set if size_aligned address range is required
197 * This function allocates an iova in the range limit_pfn to IOVA_START_PFN
198 * looking from limit_pfn instead from IOVA_START_PFN. If the size_aligned
199 * flag is set then the allocated address iova->pfn_lo will be naturally
200 * aligned on roundup_power_of_two(size).
202 struct iova *
203 alloc_iova(struct iova_domain *iovad, unsigned long size,
204 unsigned long limit_pfn,
205 bool size_aligned)
207 struct iova *new_iova;
208 int ret;
210 new_iova = alloc_iova_mem();
211 if (!new_iova)
212 return NULL;
214 /* If size aligned is set then round the size to
215 * to next power of two.
217 if (size_aligned)
218 size = __roundup_pow_of_two(size);
220 ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn,
221 new_iova, size_aligned);
223 if (ret) {
224 free_iova_mem(new_iova);
225 return NULL;
228 return new_iova;
232 * find_iova - find's an iova for a given pfn
233 * @iovad - iova domain in question.
234 * pfn - page frame number
235 * This function finds and returns an iova belonging to the
236 * given doamin which matches the given pfn.
238 struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
240 unsigned long flags;
241 struct rb_node *node;
243 /* Take the lock so that no other thread is manipulating the rbtree */
244 spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
245 node = iovad->rbroot.rb_node;
246 while (node) {
247 struct iova *iova = container_of(node, struct iova, node);
249 /* If pfn falls within iova's range, return iova */
250 if ((pfn >= iova->pfn_lo) && (pfn <= iova->pfn_hi)) {
251 spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
252 /* We are not holding the lock while this iova
253 * is referenced by the caller as the same thread
254 * which called this function also calls __free_iova()
255 * and it is by desing that only one thread can possibly
256 * reference a particular iova and hence no conflict.
258 return iova;
261 if (pfn < iova->pfn_lo)
262 node = node->rb_left;
263 else if (pfn > iova->pfn_lo)
264 node = node->rb_right;
267 spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
268 return NULL;
272 * __free_iova - frees the given iova
273 * @iovad: iova domain in question.
274 * @iova: iova in question.
275 * Frees the given iova belonging to the giving domain
277 void
278 __free_iova(struct iova_domain *iovad, struct iova *iova)
280 unsigned long flags;
282 spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
283 __cached_rbnode_delete_update(iovad, iova);
284 rb_erase(&iova->node, &iovad->rbroot);
285 spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
286 free_iova_mem(iova);
290 * free_iova - finds and frees the iova for a given pfn
291 * @iovad: - iova domain in question.
292 * @pfn: - pfn that is allocated previously
293 * This functions finds an iova for a given pfn and then
294 * frees the iova from that domain.
296 void
297 free_iova(struct iova_domain *iovad, unsigned long pfn)
299 struct iova *iova = find_iova(iovad, pfn);
300 if (iova)
301 __free_iova(iovad, iova);
306 * put_iova_domain - destroys the iova doamin
307 * @iovad: - iova domain in question.
308 * All the iova's in that domain are destroyed.
310 void put_iova_domain(struct iova_domain *iovad)
312 struct rb_node *node;
313 unsigned long flags;
315 spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
316 node = rb_first(&iovad->rbroot);
317 while (node) {
318 struct iova *iova = container_of(node, struct iova, node);
319 rb_erase(node, &iovad->rbroot);
320 free_iova_mem(iova);
321 node = rb_first(&iovad->rbroot);
323 spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
326 static int
327 __is_range_overlap(struct rb_node *node,
328 unsigned long pfn_lo, unsigned long pfn_hi)
330 struct iova *iova = container_of(node, struct iova, node);
332 if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
333 return 1;
334 return 0;
337 static struct iova *
338 __insert_new_range(struct iova_domain *iovad,
339 unsigned long pfn_lo, unsigned long pfn_hi)
341 struct iova *iova;
343 iova = alloc_iova_mem();
344 if (!iova)
345 return iova;
347 iova->pfn_hi = pfn_hi;
348 iova->pfn_lo = pfn_lo;
349 iova_insert_rbtree(&iovad->rbroot, iova);
350 return iova;
353 static void
354 __adjust_overlap_range(struct iova *iova,
355 unsigned long *pfn_lo, unsigned long *pfn_hi)
357 if (*pfn_lo < iova->pfn_lo)
358 iova->pfn_lo = *pfn_lo;
359 if (*pfn_hi > iova->pfn_hi)
360 *pfn_lo = iova->pfn_hi + 1;
364 * reserve_iova - reserves an iova in the given range
365 * @iovad: - iova domain pointer
366 * @pfn_lo: - lower page frame address
367 * @pfn_hi:- higher pfn adderss
368 * This function allocates reserves the address range from pfn_lo to pfn_hi so
369 * that this address is not dished out as part of alloc_iova.
371 struct iova *
372 reserve_iova(struct iova_domain *iovad,
373 unsigned long pfn_lo, unsigned long pfn_hi)
375 struct rb_node *node;
376 unsigned long flags;
377 struct iova *iova;
378 unsigned int overlap = 0;
380 spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
381 for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
382 if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
383 iova = container_of(node, struct iova, node);
384 __adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
385 if ((pfn_lo >= iova->pfn_lo) &&
386 (pfn_hi <= iova->pfn_hi))
387 goto finish;
388 overlap = 1;
390 } else if (overlap)
391 break;
394 /* We are here either becasue this is the first reserver node
395 * or need to insert remaining non overlap addr range
397 iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
398 finish:
400 spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
401 return iova;
405 * copy_reserved_iova - copies the reserved between domains
406 * @from: - source doamin from where to copy
407 * @to: - destination domin where to copy
408 * This function copies reserved iova's from one doamin to
409 * other.
411 void
412 copy_reserved_iova(struct iova_domain *from, struct iova_domain *to)
414 unsigned long flags;
415 struct rb_node *node;
417 spin_lock_irqsave(&from->iova_rbtree_lock, flags);
418 for (node = rb_first(&from->rbroot); node; node = rb_next(node)) {
419 struct iova *iova = container_of(node, struct iova, node);
420 struct iova *new_iova;
421 new_iova = reserve_iova(to, iova->pfn_lo, iova->pfn_hi);
422 if (!new_iova)
423 printk(KERN_ERR "Reserve iova range %lx@%lx failed\n",
424 iova->pfn_lo, iova->pfn_lo);
426 spin_unlock_irqrestore(&from->iova_rbtree_lock, flags);