xref: /freebsd/sys/dev/mthca/mthca_srq.c (revision 32100375a661c1e16588ddfa7b90ca8d26cb9786)
1 /*
2  * Copyright (c) 2005 Cisco Systems. All rights reserved.
3  *
4  * This software is available to you under a choice of one of two
5  * licenses.  You may choose to be licensed under the terms of the GNU
6  * General Public License (GPL) Version 2, available from the file
7  * COPYING in the main directory of this source tree, or the
8  * OpenIB.org BSD license below:
9  *
10  *     Redistribution and use in source and binary forms, with or
11  *     without modification, are permitted provided that the following
12  *     conditions are met:
13  *
14  *      - Redistributions of source code must retain the above
15  *        copyright notice, this list of conditions and the following
16  *        disclaimer.
17  *
18  *      - Redistributions in binary form must reproduce the above
19  *        copyright notice, this list of conditions and the following
20  *        disclaimer in the documentation and/or other materials
21  *        provided with the distribution.
22  *
23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30  * SOFTWARE.
31  */
32 
33 #include <linux/slab.h>
34 #include <linux/string.h>
35 #include <linux/sched.h>
36 
37 #include <asm/io.h>
38 
39 #include "mthca_dev.h"
40 #include "mthca_cmd.h"
41 #include "mthca_memfree.h"
42 #include "mthca_wqe.h"
43 
44 enum {
45 	MTHCA_MAX_DIRECT_SRQ_SIZE = 4 * PAGE_SIZE
46 };
47 
48 struct mthca_tavor_srq_context {
49 	__be64 wqe_base_ds;	/* low 6 bits is descriptor size */
50 	__be32 state_pd;
51 	__be32 lkey;
52 	__be32 uar;
53 	__be16 limit_watermark;
54 	__be16 wqe_cnt;
55 	u32    reserved[2];
56 };
57 
58 struct mthca_arbel_srq_context {
59 	__be32 state_logsize_srqn;
60 	__be32 lkey;
61 	__be32 db_index;
62 	__be32 logstride_usrpage;
63 	__be64 wqe_base;
64 	__be32 eq_pd;
65 	__be16 limit_watermark;
66 	__be16 wqe_cnt;
67 	u16    reserved1;
68 	__be16 wqe_counter;
69 	u32    reserved2[3];
70 };
71 
72 static void *get_wqe(struct mthca_srq *srq, int n)
73 {
74 	if (srq->is_direct)
75 		return srq->queue.direct.buf + (n << srq->wqe_shift);
76 	else
77 		return srq->queue.page_list[(n << srq->wqe_shift) >> PAGE_SHIFT].buf +
78 			((n << srq->wqe_shift) & (PAGE_SIZE - 1));
79 }
80 
81 /*
82  * Return a pointer to the location within a WQE that we're using as a
83  * link when the WQE is in the free list.  We use the imm field
84  * because in the Tavor case, posting a WQE may overwrite the next
85  * segment of the previous WQE, but a receive WQE will never touch the
86  * imm field.  This avoids corrupting our free list if the previous
87  * WQE has already completed and been put on the free list when we
88  * post the next WQE.
89  */
90 static inline int *wqe_to_link(void *wqe)
91 {
92 	return (int *) (wqe + offsetof(struct mthca_next_seg, imm));
93 }
94 
95 static void mthca_tavor_init_srq_context(struct mthca_dev *dev,
96 					 struct mthca_pd *pd,
97 					 struct mthca_srq *srq,
98 					 struct mthca_tavor_srq_context *context)
99 {
100 	memset(context, 0, sizeof *context);
101 
102 	context->wqe_base_ds = cpu_to_be64(1 << (srq->wqe_shift - 4));
103 	context->state_pd    = cpu_to_be32(pd->pd_num);
104 	context->lkey        = cpu_to_be32(srq->mr.ibmr.lkey);
105 
106 	if (pd->ibpd.uobject)
107 		context->uar =
108 			cpu_to_be32(to_mucontext(pd->ibpd.uobject->context)->uar.index);
109 	else
110 		context->uar = cpu_to_be32(dev->driver_uar.index);
111 }
112 
113 static void mthca_arbel_init_srq_context(struct mthca_dev *dev,
114 					 struct mthca_pd *pd,
115 					 struct mthca_srq *srq,
116 					 struct mthca_arbel_srq_context *context)
117 {
118 	int logsize;
119 
120 	memset(context, 0, sizeof *context);
121 	logsize = ilog2(srq->max);
122 	context->state_logsize_srqn = cpu_to_be32(logsize << 24 | srq->srqn);
123 	context->lkey = cpu_to_be32(srq->mr.ibmr.lkey);
124 	context->db_index = cpu_to_be32(srq->db_index);
125 	context->logstride_usrpage = cpu_to_be32((srq->wqe_shift - 4) << 29);
126 	if (pd->ibpd.uobject)
127 		context->logstride_usrpage |=
128 			cpu_to_be32(to_mucontext(pd->ibpd.uobject->context)->uar.index);
129 	else
130 		context->logstride_usrpage |= cpu_to_be32(dev->driver_uar.index);
131 	context->eq_pd = cpu_to_be32(MTHCA_EQ_ASYNC << 24 | pd->pd_num);
132 }
133 
134 static void mthca_free_srq_buf(struct mthca_dev *dev, struct mthca_srq *srq)
135 {
136 	mthca_buf_free(dev, srq->max << srq->wqe_shift, &srq->queue,
137 		       srq->is_direct, &srq->mr);
138 	kfree(srq->wrid);
139 }
140 
141 static int mthca_alloc_srq_buf(struct mthca_dev *dev, struct mthca_pd *pd,
142 			       struct mthca_srq *srq)
143 {
144 	struct mthca_data_seg *scatter;
145 	void *wqe;
146 	int err;
147 	int i;
148 
149 	if (pd->ibpd.uobject)
150 		return 0;
151 
152 	srq->wrid = kmalloc(srq->max * sizeof (u64), GFP_KERNEL);
153 	if (!srq->wrid)
154 		return -ENOMEM;
155 
156 	err = mthca_buf_alloc(dev, srq->max << srq->wqe_shift,
157 			      MTHCA_MAX_DIRECT_SRQ_SIZE,
158 			      &srq->queue, &srq->is_direct, pd, 1, &srq->mr);
159 	if (err) {
160 		kfree(srq->wrid);
161 		return err;
162 	}
163 
164 	/*
165 	 * Now initialize the SRQ buffer so that all of the WQEs are
166 	 * linked into the list of free WQEs.  In addition, set the
167 	 * scatter list L_Keys to the sentry value of 0x100.
168 	 */
169 	for (i = 0; i < srq->max; ++i) {
170 		struct mthca_next_seg *next;
171 
172 		next = wqe = get_wqe(srq, i);
173 
174 		if (i < srq->max - 1) {
175 			*wqe_to_link(wqe) = i + 1;
176 			next->nda_op = htonl(((i + 1) << srq->wqe_shift) | 1);
177 		} else {
178 			*wqe_to_link(wqe) = -1;
179 			next->nda_op = 0;
180 		}
181 
182 		for (scatter = wqe + sizeof (struct mthca_next_seg);
183 		     (void *) scatter < wqe + (1 << srq->wqe_shift);
184 		     ++scatter)
185 			scatter->lkey = cpu_to_be32(MTHCA_INVAL_LKEY);
186 	}
187 
188 	srq->last = get_wqe(srq, srq->max - 1);
189 
190 	return 0;
191 }
192 
193 int mthca_alloc_srq(struct mthca_dev *dev, struct mthca_pd *pd,
194 		    struct ib_srq_attr *attr, struct mthca_srq *srq)
195 {
196 	struct mthca_mailbox *mailbox;
197 	int ds;
198 	int err;
199 
200 	/* Sanity check SRQ size before proceeding */
201 	if (attr->max_wr  > dev->limits.max_srq_wqes ||
202 	    attr->max_sge > dev->limits.max_srq_sge)
203 		return -EINVAL;
204 
205 	srq->max      = attr->max_wr;
206 	srq->max_gs   = attr->max_sge;
207 	srq->counter  = 0;
208 
209 	if (mthca_is_memfree(dev))
210 		srq->max = roundup_pow_of_two(srq->max + 1);
211 	else
212 		srq->max = srq->max + 1;
213 
214 	ds = max(64UL,
215 		 roundup_pow_of_two(sizeof (struct mthca_next_seg) +
216 				    srq->max_gs * sizeof (struct mthca_data_seg)));
217 
218 	if (!mthca_is_memfree(dev) && (ds > dev->limits.max_desc_sz))
219 		return -EINVAL;
220 
221 	srq->wqe_shift = ilog2(ds);
222 
223 	srq->srqn = mthca_alloc(&dev->srq_table.alloc);
224 	if (srq->srqn == -1)
225 		return -ENOMEM;
226 
227 	if (mthca_is_memfree(dev)) {
228 		err = mthca_table_get(dev, dev->srq_table.table, srq->srqn);
229 		if (err)
230 			goto err_out;
231 
232 		if (!pd->ibpd.uobject) {
233 			srq->db_index = mthca_alloc_db(dev, MTHCA_DB_TYPE_SRQ,
234 						       srq->srqn, &srq->db);
235 			if (srq->db_index < 0) {
236 				err = -ENOMEM;
237 				goto err_out_icm;
238 			}
239 		}
240 	}
241 
242 	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
243 	if (IS_ERR(mailbox)) {
244 		err = PTR_ERR(mailbox);
245 		goto err_out_db;
246 	}
247 
248 	err = mthca_alloc_srq_buf(dev, pd, srq);
249 	if (err)
250 		goto err_out_mailbox;
251 
252 	spin_lock_init(&srq->lock);
253 	srq->refcount = 1;
254 	init_waitqueue_head(&srq->wait);
255 	mutex_init(&srq->mutex);
256 
257 	if (mthca_is_memfree(dev))
258 		mthca_arbel_init_srq_context(dev, pd, srq, mailbox->buf);
259 	else
260 		mthca_tavor_init_srq_context(dev, pd, srq, mailbox->buf);
261 
262 	err = mthca_SW2HW_SRQ(dev, mailbox, srq->srqn);
263 
264 	if (err) {
265 		mthca_warn(dev, "SW2HW_SRQ failed (%d)\n", err);
266 		goto err_out_free_buf;
267 	}
268 
269 	spin_lock_irq(&dev->srq_table.lock);
270 	if (mthca_array_set(&dev->srq_table.srq,
271 			    srq->srqn & (dev->limits.num_srqs - 1),
272 			    srq)) {
273 		spin_unlock_irq(&dev->srq_table.lock);
274 		goto err_out_free_srq;
275 	}
276 	spin_unlock_irq(&dev->srq_table.lock);
277 
278 	mthca_free_mailbox(dev, mailbox);
279 
280 	srq->first_free = 0;
281 	srq->last_free  = srq->max - 1;
282 
283 	attr->max_wr    = srq->max - 1;
284 	attr->max_sge   = srq->max_gs;
285 
286 	return 0;
287 
288 err_out_free_srq:
289 	err = mthca_HW2SW_SRQ(dev, mailbox, srq->srqn);
290 	if (err)
291 		mthca_warn(dev, "HW2SW_SRQ failed (%d)\n", err);
292 
293 err_out_free_buf:
294 	if (!pd->ibpd.uobject)
295 		mthca_free_srq_buf(dev, srq);
296 
297 err_out_mailbox:
298 	mthca_free_mailbox(dev, mailbox);
299 
300 err_out_db:
301 	if (!pd->ibpd.uobject && mthca_is_memfree(dev))
302 		mthca_free_db(dev, MTHCA_DB_TYPE_SRQ, srq->db_index);
303 
304 err_out_icm:
305 	mthca_table_put(dev, dev->srq_table.table, srq->srqn);
306 
307 err_out:
308 	mthca_free(&dev->srq_table.alloc, srq->srqn);
309 
310 	return err;
311 }
312 
313 static inline int get_srq_refcount(struct mthca_dev *dev, struct mthca_srq *srq)
314 {
315 	int c;
316 
317 	spin_lock_irq(&dev->srq_table.lock);
318 	c = srq->refcount;
319 	spin_unlock_irq(&dev->srq_table.lock);
320 
321 	return c;
322 }
323 
324 void mthca_free_srq(struct mthca_dev *dev, struct mthca_srq *srq)
325 {
326 	struct mthca_mailbox *mailbox;
327 	int err;
328 
329 	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
330 	if (IS_ERR(mailbox)) {
331 		mthca_warn(dev, "No memory for mailbox to free SRQ.\n");
332 		return;
333 	}
334 
335 	err = mthca_HW2SW_SRQ(dev, mailbox, srq->srqn);
336 	if (err)
337 		mthca_warn(dev, "HW2SW_SRQ failed (%d)\n", err);
338 
339 	spin_lock_irq(&dev->srq_table.lock);
340 	mthca_array_clear(&dev->srq_table.srq,
341 			  srq->srqn & (dev->limits.num_srqs - 1));
342 	--srq->refcount;
343 	spin_unlock_irq(&dev->srq_table.lock);
344 
345 	wait_event(srq->wait, !get_srq_refcount(dev, srq));
346 
347 	if (!srq->ibsrq.uobject) {
348 		mthca_free_srq_buf(dev, srq);
349 		if (mthca_is_memfree(dev))
350 			mthca_free_db(dev, MTHCA_DB_TYPE_SRQ, srq->db_index);
351 	}
352 
353 	mthca_table_put(dev, dev->srq_table.table, srq->srqn);
354 	mthca_free(&dev->srq_table.alloc, srq->srqn);
355 	mthca_free_mailbox(dev, mailbox);
356 }
357 
358 int mthca_modify_srq(struct ib_srq *ibsrq, struct ib_srq_attr *attr,
359 		     enum ib_srq_attr_mask attr_mask, struct ib_udata *udata)
360 {
361 	struct mthca_dev *dev = to_mdev(ibsrq->device);
362 	struct mthca_srq *srq = to_msrq(ibsrq);
363 	int ret = 0;
364 
365 	/* We don't support resizing SRQs (yet?) */
366 	if (attr_mask & IB_SRQ_MAX_WR)
367 		return -EINVAL;
368 
369 	if (attr_mask & IB_SRQ_LIMIT) {
370 		u32 max_wr = mthca_is_memfree(dev) ? srq->max - 1 : srq->max;
371 		if (attr->srq_limit > max_wr)
372 			return -EINVAL;
373 
374 		mutex_lock(&srq->mutex);
375 		ret = mthca_ARM_SRQ(dev, srq->srqn, attr->srq_limit);
376 		mutex_unlock(&srq->mutex);
377 	}
378 
379 	return ret;
380 }
381 
382 int mthca_query_srq(struct ib_srq *ibsrq, struct ib_srq_attr *srq_attr)
383 {
384 	struct mthca_dev *dev = to_mdev(ibsrq->device);
385 	struct mthca_srq *srq = to_msrq(ibsrq);
386 	struct mthca_mailbox *mailbox;
387 	struct mthca_arbel_srq_context *arbel_ctx;
388 	struct mthca_tavor_srq_context *tavor_ctx;
389 	int err;
390 
391 	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
392 	if (IS_ERR(mailbox))
393 		return PTR_ERR(mailbox);
394 
395 	err = mthca_QUERY_SRQ(dev, srq->srqn, mailbox);
396 	if (err)
397 		goto out;
398 
399 	if (mthca_is_memfree(dev)) {
400 		arbel_ctx = mailbox->buf;
401 		srq_attr->srq_limit = be16_to_cpu(arbel_ctx->limit_watermark);
402 	} else {
403 		tavor_ctx = mailbox->buf;
404 		srq_attr->srq_limit = be16_to_cpu(tavor_ctx->limit_watermark);
405 	}
406 
407 	srq_attr->max_wr  = srq->max - 1;
408 	srq_attr->max_sge = srq->max_gs;
409 
410 out:
411 	mthca_free_mailbox(dev, mailbox);
412 
413 	return err;
414 }
415 
416 void mthca_srq_event(struct mthca_dev *dev, u32 srqn,
417 		     enum ib_event_type event_type)
418 {
419 	struct mthca_srq *srq;
420 	struct ib_event event;
421 
422 	spin_lock(&dev->srq_table.lock);
423 	srq = mthca_array_get(&dev->srq_table.srq, srqn & (dev->limits.num_srqs - 1));
424 	if (srq)
425 		++srq->refcount;
426 	spin_unlock(&dev->srq_table.lock);
427 
428 	if (!srq) {
429 		mthca_warn(dev, "Async event for bogus SRQ %08x\n", srqn);
430 		return;
431 	}
432 
433 	if (!srq->ibsrq.event_handler)
434 		goto out;
435 
436 	event.device      = &dev->ib_dev;
437 	event.event       = event_type;
438 	event.element.srq = &srq->ibsrq;
439 	srq->ibsrq.event_handler(&event, srq->ibsrq.srq_context);
440 
441 out:
442 	spin_lock(&dev->srq_table.lock);
443 	if (!--srq->refcount)
444 		wake_up(&srq->wait);
445 	spin_unlock(&dev->srq_table.lock);
446 }
447 
448 /*
449  * This function must be called with IRQs disabled.
450  */
451 void mthca_free_srq_wqe(struct mthca_srq *srq, u32 wqe_addr)
452 {
453 	int ind;
454 	struct mthca_next_seg *last_free;
455 
456 	ind = wqe_addr >> srq->wqe_shift;
457 
458 	spin_lock(&srq->lock);
459 
460 	last_free = get_wqe(srq, srq->last_free);
461 	*wqe_to_link(last_free) = ind;
462 	last_free->nda_op = htonl((ind << srq->wqe_shift) | 1);
463 	*wqe_to_link(get_wqe(srq, ind)) = -1;
464 	srq->last_free = ind;
465 
466 	spin_unlock(&srq->lock);
467 }
468 
469 int mthca_tavor_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
470 			      struct ib_recv_wr **bad_wr)
471 {
472 	struct mthca_dev *dev = to_mdev(ibsrq->device);
473 	struct mthca_srq *srq = to_msrq(ibsrq);
474 	unsigned long flags;
475 	int err = 0;
476 	int first_ind;
477 	int ind;
478 	int next_ind;
479 	int nreq;
480 	int i;
481 	void *wqe;
482 	void *prev_wqe;
483 
484 	spin_lock_irqsave(&srq->lock, flags);
485 
486 	first_ind = srq->first_free;
487 
488 	for (nreq = 0; wr; wr = wr->next) {
489 		ind       = srq->first_free;
490 		wqe       = get_wqe(srq, ind);
491 		next_ind  = *wqe_to_link(wqe);
492 
493 		if (unlikely(next_ind < 0)) {
494 			mthca_err(dev, "SRQ %06x full\n", srq->srqn);
495 			err = -ENOMEM;
496 			*bad_wr = wr;
497 			break;
498 		}
499 
500 		prev_wqe  = srq->last;
501 		srq->last = wqe;
502 
503 		((struct mthca_next_seg *) wqe)->ee_nds = 0;
504 		/* flags field will always remain 0 */
505 
506 		wqe += sizeof (struct mthca_next_seg);
507 
508 		if (unlikely(wr->num_sge > srq->max_gs)) {
509 			err = -EINVAL;
510 			*bad_wr = wr;
511 			srq->last = prev_wqe;
512 			break;
513 		}
514 
515 		for (i = 0; i < wr->num_sge; ++i) {
516 			mthca_set_data_seg(wqe, wr->sg_list + i);
517 			wqe += sizeof (struct mthca_data_seg);
518 		}
519 
520 		if (i < srq->max_gs)
521 			mthca_set_data_seg_inval(wqe);
522 
523 		((struct mthca_next_seg *) prev_wqe)->ee_nds =
524 			cpu_to_be32(MTHCA_NEXT_DBD);
525 
526 		srq->wrid[ind]  = wr->wr_id;
527 		srq->first_free = next_ind;
528 
529 		++nreq;
530 		if (unlikely(nreq == MTHCA_TAVOR_MAX_WQES_PER_RECV_DB)) {
531 			nreq = 0;
532 
533 			/*
534 			 * Make sure that descriptors are written
535 			 * before doorbell is rung.
536 			 */
537 			wmb();
538 
539 			mthca_write64(first_ind << srq->wqe_shift, srq->srqn << 8,
540 				      dev->kar + MTHCA_RECEIVE_DOORBELL,
541 				      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
542 
543 			first_ind = srq->first_free;
544 		}
545 	}
546 
547 	if (likely(nreq)) {
548 		/*
549 		 * Make sure that descriptors are written before
550 		 * doorbell is rung.
551 		 */
552 		wmb();
553 
554 		mthca_write64(first_ind << srq->wqe_shift, (srq->srqn << 8) | nreq,
555 			      dev->kar + MTHCA_RECEIVE_DOORBELL,
556 			      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
557 	}
558 
559 	/*
560 	 * Make sure doorbells don't leak out of SRQ spinlock and
561 	 * reach the HCA out of order:
562 	 */
563 	mmiowb();
564 
565 	spin_unlock_irqrestore(&srq->lock, flags);
566 	return err;
567 }
568 
569 int mthca_arbel_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
570 			      struct ib_recv_wr **bad_wr)
571 {
572 	struct mthca_dev *dev = to_mdev(ibsrq->device);
573 	struct mthca_srq *srq = to_msrq(ibsrq);
574 	unsigned long flags;
575 	int err = 0;
576 	int ind;
577 	int next_ind;
578 	int nreq;
579 	int i;
580 	void *wqe;
581 
582 	spin_lock_irqsave(&srq->lock, flags);
583 
584 	for (nreq = 0; wr; ++nreq, wr = wr->next) {
585 		ind       = srq->first_free;
586 		wqe       = get_wqe(srq, ind);
587 		next_ind  = *wqe_to_link(wqe);
588 
589 		if (unlikely(next_ind < 0)) {
590 			mthca_err(dev, "SRQ %06x full\n", srq->srqn);
591 			err = -ENOMEM;
592 			*bad_wr = wr;
593 			break;
594 		}
595 
596 		((struct mthca_next_seg *) wqe)->ee_nds = 0;
597 		/* flags field will always remain 0 */
598 
599 		wqe += sizeof (struct mthca_next_seg);
600 
601 		if (unlikely(wr->num_sge > srq->max_gs)) {
602 			err = -EINVAL;
603 			*bad_wr = wr;
604 			break;
605 		}
606 
607 		for (i = 0; i < wr->num_sge; ++i) {
608 			mthca_set_data_seg(wqe, wr->sg_list + i);
609 			wqe += sizeof (struct mthca_data_seg);
610 		}
611 
612 		if (i < srq->max_gs)
613 			mthca_set_data_seg_inval(wqe);
614 
615 		srq->wrid[ind]  = wr->wr_id;
616 		srq->first_free = next_ind;
617 	}
618 
619 	if (likely(nreq)) {
620 		srq->counter += nreq;
621 
622 		/*
623 		 * Make sure that descriptors are written before
624 		 * we write doorbell record.
625 		 */
626 		wmb();
627 		*srq->db = cpu_to_be32(srq->counter);
628 	}
629 
630 	spin_unlock_irqrestore(&srq->lock, flags);
631 	return err;
632 }
633 
634 int mthca_max_srq_sge(struct mthca_dev *dev)
635 {
636 	if (mthca_is_memfree(dev))
637 		return dev->limits.max_sg;
638 
639 	/*
640 	 * SRQ allocations are based on powers of 2 for Tavor,
641 	 * (although they only need to be multiples of 16 bytes).
642 	 *
643 	 * Therefore, we need to base the max number of sg entries on
644 	 * the largest power of 2 descriptor size that is <= to the
645 	 * actual max WQE descriptor size, rather than return the
646 	 * max_sg value given by the firmware (which is based on WQE
647 	 * sizes as multiples of 16, not powers of 2).
648 	 *
649 	 * If SRQ implementation is changed for Tavor to be based on
650 	 * multiples of 16, the calculation below can be deleted and
651 	 * the FW max_sg value returned.
652 	 */
653 	return min_t(int, dev->limits.max_sg,
654 		     ((1 << (fls(dev->limits.max_desc_sz) - 1)) -
655 		      sizeof (struct mthca_next_seg)) /
656 		     sizeof (struct mthca_data_seg));
657 }
658 
659 int mthca_init_srq_table(struct mthca_dev *dev)
660 {
661 	int err;
662 
663 	if (!(dev->mthca_flags & MTHCA_FLAG_SRQ))
664 		return 0;
665 
666 	spin_lock_init(&dev->srq_table.lock);
667 
668 	err = mthca_alloc_init(&dev->srq_table.alloc,
669 			       dev->limits.num_srqs,
670 			       dev->limits.num_srqs - 1,
671 			       dev->limits.reserved_srqs);
672 	if (err)
673 		return err;
674 
675 	err = mthca_array_init(&dev->srq_table.srq,
676 			       dev->limits.num_srqs);
677 	if (err)
678 		mthca_alloc_cleanup(&dev->srq_table.alloc);
679 
680 	return err;
681 }
682 
683 void mthca_cleanup_srq_table(struct mthca_dev *dev)
684 {
685 	if (!(dev->mthca_flags & MTHCA_FLAG_SRQ))
686 		return;
687 
688 	mthca_array_cleanup(&dev->srq_table.srq, dev->limits.num_srqs);
689 	mthca_alloc_cleanup(&dev->srq_table.alloc);
690 }
691