xref: /openbmc/linux/drivers/infiniband/hw/mthca/mthca_memfree.c (revision 8fa5723aa7e053d498336b48448b292fc2e0458b)
1 /*
2  * Copyright (c) 2004, 2005 Topspin Communications.  All rights reserved.
3  * Copyright (c) 2005 Cisco Systems.  All rights reserved.
4  * Copyright (c) 2005 Mellanox Technologies. All rights reserved.
5  *
6  * This software is available to you under a choice of one of two
7  * licenses.  You may choose to be licensed under the terms of the GNU
8  * General Public License (GPL) Version 2, available from the file
9  * COPYING in the main directory of this source tree, or the
10  * OpenIB.org BSD license below:
11  *
12  *     Redistribution and use in source and binary forms, with or
13  *     without modification, are permitted provided that the following
14  *     conditions are met:
15  *
16  *      - Redistributions of source code must retain the above
17  *        copyright notice, this list of conditions and the following
18  *        disclaimer.
19  *
20  *      - Redistributions in binary form must reproduce the above
21  *        copyright notice, this list of conditions and the following
22  *        disclaimer in the documentation and/or other materials
23  *        provided with the distribution.
24  *
25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
26  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
27  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
28  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
29  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
30  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
31  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
32  * SOFTWARE.
33  */
34 
35 #include <linux/mm.h>
36 #include <linux/scatterlist.h>
37 #include <linux/sched.h>
38 
39 #include <asm/page.h>
40 
41 #include "mthca_memfree.h"
42 #include "mthca_dev.h"
43 #include "mthca_cmd.h"
44 
45 /*
46  * We allocate in as big chunks as we can, up to a maximum of 256 KB
47  * per chunk.
48  */
49 enum {
50 	MTHCA_ICM_ALLOC_SIZE   = 1 << 18,
51 	MTHCA_TABLE_CHUNK_SIZE = 1 << 18
52 };
53 
54 struct mthca_user_db_table {
55 	struct mutex mutex;
56 	struct {
57 		u64                uvirt;
58 		struct scatterlist mem;
59 		int                refcount;
60 	}                page[0];
61 };
62 
63 static void mthca_free_icm_pages(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)
64 {
65 	int i;
66 
67 	if (chunk->nsg > 0)
68 		pci_unmap_sg(dev->pdev, chunk->mem, chunk->npages,
69 			     PCI_DMA_BIDIRECTIONAL);
70 
71 	for (i = 0; i < chunk->npages; ++i)
72 		__free_pages(sg_page(&chunk->mem[i]),
73 			     get_order(chunk->mem[i].length));
74 }
75 
76 static void mthca_free_icm_coherent(struct mthca_dev *dev, struct mthca_icm_chunk *chunk)
77 {
78 	int i;
79 
80 	for (i = 0; i < chunk->npages; ++i) {
81 		dma_free_coherent(&dev->pdev->dev, chunk->mem[i].length,
82 				  lowmem_page_address(sg_page(&chunk->mem[i])),
83 				  sg_dma_address(&chunk->mem[i]));
84 	}
85 }
86 
87 void mthca_free_icm(struct mthca_dev *dev, struct mthca_icm *icm, int coherent)
88 {
89 	struct mthca_icm_chunk *chunk, *tmp;
90 
91 	if (!icm)
92 		return;
93 
94 	list_for_each_entry_safe(chunk, tmp, &icm->chunk_list, list) {
95 		if (coherent)
96 			mthca_free_icm_coherent(dev, chunk);
97 		else
98 			mthca_free_icm_pages(dev, chunk);
99 
100 		kfree(chunk);
101 	}
102 
103 	kfree(icm);
104 }
105 
106 static int mthca_alloc_icm_pages(struct scatterlist *mem, int order, gfp_t gfp_mask)
107 {
108 	struct page *page;
109 
110 	/*
111 	 * Use __GFP_ZERO because buggy firmware assumes ICM pages are
112 	 * cleared, and subtle failures are seen if they aren't.
113 	 */
114 	page = alloc_pages(gfp_mask | __GFP_ZERO, order);
115 	if (!page)
116 		return -ENOMEM;
117 
118 	sg_set_page(mem, page, PAGE_SIZE << order, 0);
119 	return 0;
120 }
121 
122 static int mthca_alloc_icm_coherent(struct device *dev, struct scatterlist *mem,
123 				    int order, gfp_t gfp_mask)
124 {
125 	void *buf = dma_alloc_coherent(dev, PAGE_SIZE << order, &sg_dma_address(mem),
126 				       gfp_mask);
127 	if (!buf)
128 		return -ENOMEM;
129 
130 	sg_set_buf(mem, buf, PAGE_SIZE << order);
131 	BUG_ON(mem->offset);
132 	sg_dma_len(mem) = PAGE_SIZE << order;
133 	return 0;
134 }
135 
136 struct mthca_icm *mthca_alloc_icm(struct mthca_dev *dev, int npages,
137 				  gfp_t gfp_mask, int coherent)
138 {
139 	struct mthca_icm *icm;
140 	struct mthca_icm_chunk *chunk = NULL;
141 	int cur_order;
142 	int ret;
143 
144 	/* We use sg_set_buf for coherent allocs, which assumes low memory */
145 	BUG_ON(coherent && (gfp_mask & __GFP_HIGHMEM));
146 
147 	icm = kmalloc(sizeof *icm, gfp_mask & ~(__GFP_HIGHMEM | __GFP_NOWARN));
148 	if (!icm)
149 		return icm;
150 
151 	icm->refcount = 0;
152 	INIT_LIST_HEAD(&icm->chunk_list);
153 
154 	cur_order = get_order(MTHCA_ICM_ALLOC_SIZE);
155 
156 	while (npages > 0) {
157 		if (!chunk) {
158 			chunk = kmalloc(sizeof *chunk,
159 					gfp_mask & ~(__GFP_HIGHMEM | __GFP_NOWARN));
160 			if (!chunk)
161 				goto fail;
162 
163 			sg_init_table(chunk->mem, MTHCA_ICM_CHUNK_LEN);
164 			chunk->npages = 0;
165 			chunk->nsg    = 0;
166 			list_add_tail(&chunk->list, &icm->chunk_list);
167 		}
168 
169 		while (1 << cur_order > npages)
170 			--cur_order;
171 
172 		if (coherent)
173 			ret = mthca_alloc_icm_coherent(&dev->pdev->dev,
174 						       &chunk->mem[chunk->npages],
175 						       cur_order, gfp_mask);
176 		else
177 			ret = mthca_alloc_icm_pages(&chunk->mem[chunk->npages],
178 						    cur_order, gfp_mask);
179 
180 		if (!ret) {
181 			++chunk->npages;
182 
183 			if (coherent)
184 				++chunk->nsg;
185 			else if (chunk->npages == MTHCA_ICM_CHUNK_LEN) {
186 				chunk->nsg = pci_map_sg(dev->pdev, chunk->mem,
187 							chunk->npages,
188 							PCI_DMA_BIDIRECTIONAL);
189 
190 				if (chunk->nsg <= 0)
191 					goto fail;
192 			}
193 
194 			if (chunk->npages == MTHCA_ICM_CHUNK_LEN)
195 				chunk = NULL;
196 
197 			npages -= 1 << cur_order;
198 		} else {
199 			--cur_order;
200 			if (cur_order < 0)
201 				goto fail;
202 		}
203 	}
204 
205 	if (!coherent && chunk) {
206 		chunk->nsg = pci_map_sg(dev->pdev, chunk->mem,
207 					chunk->npages,
208 					PCI_DMA_BIDIRECTIONAL);
209 
210 		if (chunk->nsg <= 0)
211 			goto fail;
212 	}
213 
214 	return icm;
215 
216 fail:
217 	mthca_free_icm(dev, icm, coherent);
218 	return NULL;
219 }
220 
221 int mthca_table_get(struct mthca_dev *dev, struct mthca_icm_table *table, int obj)
222 {
223 	int i = (obj & (table->num_obj - 1)) * table->obj_size / MTHCA_TABLE_CHUNK_SIZE;
224 	int ret = 0;
225 	u8 status;
226 
227 	mutex_lock(&table->mutex);
228 
229 	if (table->icm[i]) {
230 		++table->icm[i]->refcount;
231 		goto out;
232 	}
233 
234 	table->icm[i] = mthca_alloc_icm(dev, MTHCA_TABLE_CHUNK_SIZE >> PAGE_SHIFT,
235 					(table->lowmem ? GFP_KERNEL : GFP_HIGHUSER) |
236 					__GFP_NOWARN, table->coherent);
237 	if (!table->icm[i]) {
238 		ret = -ENOMEM;
239 		goto out;
240 	}
241 
242 	if (mthca_MAP_ICM(dev, table->icm[i], table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
243 			  &status) || status) {
244 		mthca_free_icm(dev, table->icm[i], table->coherent);
245 		table->icm[i] = NULL;
246 		ret = -ENOMEM;
247 		goto out;
248 	}
249 
250 	++table->icm[i]->refcount;
251 
252 out:
253 	mutex_unlock(&table->mutex);
254 	return ret;
255 }
256 
257 void mthca_table_put(struct mthca_dev *dev, struct mthca_icm_table *table, int obj)
258 {
259 	int i;
260 	u8 status;
261 
262 	if (!mthca_is_memfree(dev))
263 		return;
264 
265 	i = (obj & (table->num_obj - 1)) * table->obj_size / MTHCA_TABLE_CHUNK_SIZE;
266 
267 	mutex_lock(&table->mutex);
268 
269 	if (--table->icm[i]->refcount == 0) {
270 		mthca_UNMAP_ICM(dev, table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
271 				MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE,
272 				&status);
273 		mthca_free_icm(dev, table->icm[i], table->coherent);
274 		table->icm[i] = NULL;
275 	}
276 
277 	mutex_unlock(&table->mutex);
278 }
279 
280 void *mthca_table_find(struct mthca_icm_table *table, int obj, dma_addr_t *dma_handle)
281 {
282 	int idx, offset, dma_offset, i;
283 	struct mthca_icm_chunk *chunk;
284 	struct mthca_icm *icm;
285 	struct page *page = NULL;
286 
287 	if (!table->lowmem)
288 		return NULL;
289 
290 	mutex_lock(&table->mutex);
291 
292 	idx = (obj & (table->num_obj - 1)) * table->obj_size;
293 	icm = table->icm[idx / MTHCA_TABLE_CHUNK_SIZE];
294 	dma_offset = offset = idx % MTHCA_TABLE_CHUNK_SIZE;
295 
296 	if (!icm)
297 		goto out;
298 
299 	list_for_each_entry(chunk, &icm->chunk_list, list) {
300 		for (i = 0; i < chunk->npages; ++i) {
301 			if (dma_handle && dma_offset >= 0) {
302 				if (sg_dma_len(&chunk->mem[i]) > dma_offset)
303 					*dma_handle = sg_dma_address(&chunk->mem[i]) +
304 						dma_offset;
305 				dma_offset -= sg_dma_len(&chunk->mem[i]);
306 			}
307 			/* DMA mapping can merge pages but not split them,
308 			 * so if we found the page, dma_handle has already
309 			 * been assigned to. */
310 			if (chunk->mem[i].length > offset) {
311 				page = sg_page(&chunk->mem[i]);
312 				goto out;
313 			}
314 			offset -= chunk->mem[i].length;
315 		}
316 	}
317 
318 out:
319 	mutex_unlock(&table->mutex);
320 	return page ? lowmem_page_address(page) + offset : NULL;
321 }
322 
323 int mthca_table_get_range(struct mthca_dev *dev, struct mthca_icm_table *table,
324 			  int start, int end)
325 {
326 	int inc = MTHCA_TABLE_CHUNK_SIZE / table->obj_size;
327 	int i, err;
328 
329 	for (i = start; i <= end; i += inc) {
330 		err = mthca_table_get(dev, table, i);
331 		if (err)
332 			goto fail;
333 	}
334 
335 	return 0;
336 
337 fail:
338 	while (i > start) {
339 		i -= inc;
340 		mthca_table_put(dev, table, i);
341 	}
342 
343 	return err;
344 }
345 
346 void mthca_table_put_range(struct mthca_dev *dev, struct mthca_icm_table *table,
347 			   int start, int end)
348 {
349 	int i;
350 
351 	if (!mthca_is_memfree(dev))
352 		return;
353 
354 	for (i = start; i <= end; i += MTHCA_TABLE_CHUNK_SIZE / table->obj_size)
355 		mthca_table_put(dev, table, i);
356 }
357 
358 struct mthca_icm_table *mthca_alloc_icm_table(struct mthca_dev *dev,
359 					      u64 virt, int obj_size,
360 					      int nobj, int reserved,
361 					      int use_lowmem, int use_coherent)
362 {
363 	struct mthca_icm_table *table;
364 	int obj_per_chunk;
365 	int num_icm;
366 	unsigned chunk_size;
367 	int i;
368 	u8 status;
369 
370 	obj_per_chunk = MTHCA_TABLE_CHUNK_SIZE / obj_size;
371 	num_icm = DIV_ROUND_UP(nobj, obj_per_chunk);
372 
373 	table = kmalloc(sizeof *table + num_icm * sizeof *table->icm, GFP_KERNEL);
374 	if (!table)
375 		return NULL;
376 
377 	table->virt     = virt;
378 	table->num_icm  = num_icm;
379 	table->num_obj  = nobj;
380 	table->obj_size = obj_size;
381 	table->lowmem   = use_lowmem;
382 	table->coherent = use_coherent;
383 	mutex_init(&table->mutex);
384 
385 	for (i = 0; i < num_icm; ++i)
386 		table->icm[i] = NULL;
387 
388 	for (i = 0; i * MTHCA_TABLE_CHUNK_SIZE < reserved * obj_size; ++i) {
389 		chunk_size = MTHCA_TABLE_CHUNK_SIZE;
390 		if ((i + 1) * MTHCA_TABLE_CHUNK_SIZE > nobj * obj_size)
391 			chunk_size = nobj * obj_size - i * MTHCA_TABLE_CHUNK_SIZE;
392 
393 		table->icm[i] = mthca_alloc_icm(dev, chunk_size >> PAGE_SHIFT,
394 						(use_lowmem ? GFP_KERNEL : GFP_HIGHUSER) |
395 						__GFP_NOWARN, use_coherent);
396 		if (!table->icm[i])
397 			goto err;
398 		if (mthca_MAP_ICM(dev, table->icm[i], virt + i * MTHCA_TABLE_CHUNK_SIZE,
399 				  &status) || status) {
400 			mthca_free_icm(dev, table->icm[i], table->coherent);
401 			table->icm[i] = NULL;
402 			goto err;
403 		}
404 
405 		/*
406 		 * Add a reference to this ICM chunk so that it never
407 		 * gets freed (since it contains reserved firmware objects).
408 		 */
409 		++table->icm[i]->refcount;
410 	}
411 
412 	return table;
413 
414 err:
415 	for (i = 0; i < num_icm; ++i)
416 		if (table->icm[i]) {
417 			mthca_UNMAP_ICM(dev, virt + i * MTHCA_TABLE_CHUNK_SIZE,
418 					MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE,
419 					&status);
420 			mthca_free_icm(dev, table->icm[i], table->coherent);
421 		}
422 
423 	kfree(table);
424 
425 	return NULL;
426 }
427 
428 void mthca_free_icm_table(struct mthca_dev *dev, struct mthca_icm_table *table)
429 {
430 	int i;
431 	u8 status;
432 
433 	for (i = 0; i < table->num_icm; ++i)
434 		if (table->icm[i]) {
435 			mthca_UNMAP_ICM(dev, table->virt + i * MTHCA_TABLE_CHUNK_SIZE,
436 					MTHCA_TABLE_CHUNK_SIZE / MTHCA_ICM_PAGE_SIZE,
437 					&status);
438 			mthca_free_icm(dev, table->icm[i], table->coherent);
439 		}
440 
441 	kfree(table);
442 }
443 
444 static u64 mthca_uarc_virt(struct mthca_dev *dev, struct mthca_uar *uar, int page)
445 {
446 	return dev->uar_table.uarc_base +
447 		uar->index * dev->uar_table.uarc_size +
448 		page * MTHCA_ICM_PAGE_SIZE;
449 }
450 
451 int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
452 		      struct mthca_user_db_table *db_tab, int index, u64 uaddr)
453 {
454 	struct page *pages[1];
455 	int ret = 0;
456 	u8 status;
457 	int i;
458 
459 	if (!mthca_is_memfree(dev))
460 		return 0;
461 
462 	if (index < 0 || index > dev->uar_table.uarc_size / 8)
463 		return -EINVAL;
464 
465 	mutex_lock(&db_tab->mutex);
466 
467 	i = index / MTHCA_DB_REC_PER_PAGE;
468 
469 	if ((db_tab->page[i].refcount >= MTHCA_DB_REC_PER_PAGE)       ||
470 	    (db_tab->page[i].uvirt && db_tab->page[i].uvirt != uaddr) ||
471 	    (uaddr & 4095)) {
472 		ret = -EINVAL;
473 		goto out;
474 	}
475 
476 	if (db_tab->page[i].refcount) {
477 		++db_tab->page[i].refcount;
478 		goto out;
479 	}
480 
481 	ret = get_user_pages(current, current->mm, uaddr & PAGE_MASK, 1, 1, 0,
482 			     pages, NULL);
483 	if (ret < 0)
484 		goto out;
485 
486 	sg_set_page(&db_tab->page[i].mem, pages[0], MTHCA_ICM_PAGE_SIZE,
487 			uaddr & ~PAGE_MASK);
488 
489 	ret = pci_map_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
490 	if (ret < 0) {
491 		put_page(pages[0]);
492 		goto out;
493 	}
494 
495 	ret = mthca_MAP_ICM_page(dev, sg_dma_address(&db_tab->page[i].mem),
496 				 mthca_uarc_virt(dev, uar, i), &status);
497 	if (!ret && status)
498 		ret = -EINVAL;
499 	if (ret) {
500 		pci_unmap_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
501 		put_page(sg_page(&db_tab->page[i].mem));
502 		goto out;
503 	}
504 
505 	db_tab->page[i].uvirt    = uaddr;
506 	db_tab->page[i].refcount = 1;
507 
508 out:
509 	mutex_unlock(&db_tab->mutex);
510 	return ret;
511 }
512 
513 void mthca_unmap_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
514 			 struct mthca_user_db_table *db_tab, int index)
515 {
516 	if (!mthca_is_memfree(dev))
517 		return;
518 
519 	/*
520 	 * To make our bookkeeping simpler, we don't unmap DB
521 	 * pages until we clean up the whole db table.
522 	 */
523 
524 	mutex_lock(&db_tab->mutex);
525 
526 	--db_tab->page[index / MTHCA_DB_REC_PER_PAGE].refcount;
527 
528 	mutex_unlock(&db_tab->mutex);
529 }
530 
531 struct mthca_user_db_table *mthca_init_user_db_tab(struct mthca_dev *dev)
532 {
533 	struct mthca_user_db_table *db_tab;
534 	int npages;
535 	int i;
536 
537 	if (!mthca_is_memfree(dev))
538 		return NULL;
539 
540 	npages = dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE;
541 	db_tab = kmalloc(sizeof *db_tab + npages * sizeof *db_tab->page, GFP_KERNEL);
542 	if (!db_tab)
543 		return ERR_PTR(-ENOMEM);
544 
545 	mutex_init(&db_tab->mutex);
546 	for (i = 0; i < npages; ++i) {
547 		db_tab->page[i].refcount = 0;
548 		db_tab->page[i].uvirt    = 0;
549 		sg_init_table(&db_tab->page[i].mem, 1);
550 	}
551 
552 	return db_tab;
553 }
554 
555 void mthca_cleanup_user_db_tab(struct mthca_dev *dev, struct mthca_uar *uar,
556 			       struct mthca_user_db_table *db_tab)
557 {
558 	int i;
559 	u8 status;
560 
561 	if (!mthca_is_memfree(dev))
562 		return;
563 
564 	for (i = 0; i < dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE; ++i) {
565 		if (db_tab->page[i].uvirt) {
566 			mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, uar, i), 1, &status);
567 			pci_unmap_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
568 			put_page(sg_page(&db_tab->page[i].mem));
569 		}
570 	}
571 
572 	kfree(db_tab);
573 }
574 
575 int mthca_alloc_db(struct mthca_dev *dev, enum mthca_db_type type,
576 		   u32 qn, __be32 **db)
577 {
578 	int group;
579 	int start, end, dir;
580 	int i, j;
581 	struct mthca_db_page *page;
582 	int ret = 0;
583 	u8 status;
584 
585 	mutex_lock(&dev->db_tab->mutex);
586 
587 	switch (type) {
588 	case MTHCA_DB_TYPE_CQ_ARM:
589 	case MTHCA_DB_TYPE_SQ:
590 		group = 0;
591 		start = 0;
592 		end   = dev->db_tab->max_group1;
593 		dir   = 1;
594 		break;
595 
596 	case MTHCA_DB_TYPE_CQ_SET_CI:
597 	case MTHCA_DB_TYPE_RQ:
598 	case MTHCA_DB_TYPE_SRQ:
599 		group = 1;
600 		start = dev->db_tab->npages - 1;
601 		end   = dev->db_tab->min_group2;
602 		dir   = -1;
603 		break;
604 
605 	default:
606 		ret = -EINVAL;
607 		goto out;
608 	}
609 
610 	for (i = start; i != end; i += dir)
611 		if (dev->db_tab->page[i].db_rec &&
612 		    !bitmap_full(dev->db_tab->page[i].used,
613 				 MTHCA_DB_REC_PER_PAGE)) {
614 			page = dev->db_tab->page + i;
615 			goto found;
616 		}
617 
618 	for (i = start; i != end; i += dir)
619 		if (!dev->db_tab->page[i].db_rec) {
620 			page = dev->db_tab->page + i;
621 			goto alloc;
622 		}
623 
624 	if (dev->db_tab->max_group1 >= dev->db_tab->min_group2 - 1) {
625 		ret = -ENOMEM;
626 		goto out;
627 	}
628 
629 	if (group == 0)
630 		++dev->db_tab->max_group1;
631 	else
632 		--dev->db_tab->min_group2;
633 
634 	page = dev->db_tab->page + end;
635 
636 alloc:
637 	page->db_rec = dma_alloc_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
638 					  &page->mapping, GFP_KERNEL);
639 	if (!page->db_rec) {
640 		ret = -ENOMEM;
641 		goto out;
642 	}
643 	memset(page->db_rec, 0, MTHCA_ICM_PAGE_SIZE);
644 
645 	ret = mthca_MAP_ICM_page(dev, page->mapping,
646 				 mthca_uarc_virt(dev, &dev->driver_uar, i), &status);
647 	if (!ret && status)
648 		ret = -EINVAL;
649 	if (ret) {
650 		dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
651 				  page->db_rec, page->mapping);
652 		goto out;
653 	}
654 
655 	bitmap_zero(page->used, MTHCA_DB_REC_PER_PAGE);
656 
657 found:
658 	j = find_first_zero_bit(page->used, MTHCA_DB_REC_PER_PAGE);
659 	set_bit(j, page->used);
660 
661 	if (group == 1)
662 		j = MTHCA_DB_REC_PER_PAGE - 1 - j;
663 
664 	ret = i * MTHCA_DB_REC_PER_PAGE + j;
665 
666 	page->db_rec[j] = cpu_to_be64((qn << 8) | (type << 5));
667 
668 	*db = (__be32 *) &page->db_rec[j];
669 
670 out:
671 	mutex_unlock(&dev->db_tab->mutex);
672 
673 	return ret;
674 }
675 
676 void mthca_free_db(struct mthca_dev *dev, int type, int db_index)
677 {
678 	int i, j;
679 	struct mthca_db_page *page;
680 	u8 status;
681 
682 	i = db_index / MTHCA_DB_REC_PER_PAGE;
683 	j = db_index % MTHCA_DB_REC_PER_PAGE;
684 
685 	page = dev->db_tab->page + i;
686 
687 	mutex_lock(&dev->db_tab->mutex);
688 
689 	page->db_rec[j] = 0;
690 	if (i >= dev->db_tab->min_group2)
691 		j = MTHCA_DB_REC_PER_PAGE - 1 - j;
692 	clear_bit(j, page->used);
693 
694 	if (bitmap_empty(page->used, MTHCA_DB_REC_PER_PAGE) &&
695 	    i >= dev->db_tab->max_group1 - 1) {
696 		mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, &dev->driver_uar, i), 1, &status);
697 
698 		dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
699 				  page->db_rec, page->mapping);
700 		page->db_rec = NULL;
701 
702 		if (i == dev->db_tab->max_group1) {
703 			--dev->db_tab->max_group1;
704 			/* XXX may be able to unmap more pages now */
705 		}
706 		if (i == dev->db_tab->min_group2)
707 			++dev->db_tab->min_group2;
708 	}
709 
710 	mutex_unlock(&dev->db_tab->mutex);
711 }
712 
713 int mthca_init_db_tab(struct mthca_dev *dev)
714 {
715 	int i;
716 
717 	if (!mthca_is_memfree(dev))
718 		return 0;
719 
720 	dev->db_tab = kmalloc(sizeof *dev->db_tab, GFP_KERNEL);
721 	if (!dev->db_tab)
722 		return -ENOMEM;
723 
724 	mutex_init(&dev->db_tab->mutex);
725 
726 	dev->db_tab->npages     = dev->uar_table.uarc_size / MTHCA_ICM_PAGE_SIZE;
727 	dev->db_tab->max_group1 = 0;
728 	dev->db_tab->min_group2 = dev->db_tab->npages - 1;
729 
730 	dev->db_tab->page = kmalloc(dev->db_tab->npages *
731 				    sizeof *dev->db_tab->page,
732 				    GFP_KERNEL);
733 	if (!dev->db_tab->page) {
734 		kfree(dev->db_tab);
735 		return -ENOMEM;
736 	}
737 
738 	for (i = 0; i < dev->db_tab->npages; ++i)
739 		dev->db_tab->page[i].db_rec = NULL;
740 
741 	return 0;
742 }
743 
744 void mthca_cleanup_db_tab(struct mthca_dev *dev)
745 {
746 	int i;
747 	u8 status;
748 
749 	if (!mthca_is_memfree(dev))
750 		return;
751 
752 	/*
753 	 * Because we don't always free our UARC pages when they
754 	 * become empty to make mthca_free_db() simpler we need to
755 	 * make a sweep through the doorbell pages and free any
756 	 * leftover pages now.
757 	 */
758 	for (i = 0; i < dev->db_tab->npages; ++i) {
759 		if (!dev->db_tab->page[i].db_rec)
760 			continue;
761 
762 		if (!bitmap_empty(dev->db_tab->page[i].used, MTHCA_DB_REC_PER_PAGE))
763 			mthca_warn(dev, "Kernel UARC page %d not empty\n", i);
764 
765 		mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, &dev->driver_uar, i), 1, &status);
766 
767 		dma_free_coherent(&dev->pdev->dev, MTHCA_ICM_PAGE_SIZE,
768 				  dev->db_tab->page[i].db_rec,
769 				  dev->db_tab->page[i].mapping);
770 	}
771 
772 	kfree(dev->db_tab->page);
773 	kfree(dev->db_tab);
774 }
775