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 <rdma/uverbs_ioctl.h>
40 
41 #include "mthca_dev.h"
42 #include "mthca_cmd.h"
43 #include "mthca_memfree.h"
44 #include "mthca_wqe.h"
45 
46 enum {
47 	MTHCA_MAX_DIRECT_SRQ_SIZE = 4 * PAGE_SIZE
48 };
49 
50 struct mthca_tavor_srq_context {
51 	__be64 wqe_base_ds;	/* low 6 bits is descriptor size */
52 	__be32 state_pd;
53 	__be32 lkey;
54 	__be32 uar;
55 	__be16 limit_watermark;
56 	__be16 wqe_cnt;
57 	u32    reserved[2];
58 };
59 
60 struct mthca_arbel_srq_context {
61 	__be32 state_logsize_srqn;
62 	__be32 lkey;
63 	__be32 db_index;
64 	__be32 logstride_usrpage;
65 	__be64 wqe_base;
66 	__be32 eq_pd;
67 	__be16 limit_watermark;
68 	__be16 wqe_cnt;
69 	u16    reserved1;
70 	__be16 wqe_counter;
71 	u32    reserved2[3];
72 };
73 
74 static void *get_wqe(struct mthca_srq *srq, int n)
75 {
76 	if (srq->is_direct)
77 		return srq->queue.direct.buf + (n << srq->wqe_shift);
78 	else
79 		return srq->queue.page_list[(n << srq->wqe_shift) >> PAGE_SHIFT].buf +
80 			((n << srq->wqe_shift) & (PAGE_SIZE - 1));
81 }
82 
83 /*
84  * Return a pointer to the location within a WQE that we're using as a
85  * link when the WQE is in the free list.  We use the imm field
86  * because in the Tavor case, posting a WQE may overwrite the next
87  * segment of the previous WQE, but a receive WQE will never touch the
88  * imm field.  This avoids corrupting our free list if the previous
89  * WQE has already completed and been put on the free list when we
90  * post the next WQE.
91  */
92 static inline int *wqe_to_link(void *wqe)
93 {
94 	return (int *) (wqe + offsetof(struct mthca_next_seg, imm));
95 }
96 
97 static void mthca_tavor_init_srq_context(struct mthca_dev *dev,
98 					 struct mthca_pd *pd,
99 					 struct mthca_srq *srq,
100 					 struct mthca_tavor_srq_context *context,
101 					 struct ib_udata *udata)
102 {
103 	struct mthca_ucontext *ucontext = rdma_udata_to_drv_context(
104 		udata, struct mthca_ucontext, ibucontext);
105 
106 	memset(context, 0, sizeof *context);
107 
108 	context->wqe_base_ds = cpu_to_be64(1 << (srq->wqe_shift - 4));
109 	context->state_pd    = cpu_to_be32(pd->pd_num);
110 	context->lkey        = cpu_to_be32(srq->mr.ibmr.lkey);
111 
112 	if (udata)
113 		context->uar = cpu_to_be32(ucontext->uar.index);
114 	else
115 		context->uar = cpu_to_be32(dev->driver_uar.index);
116 }
117 
118 static void mthca_arbel_init_srq_context(struct mthca_dev *dev,
119 					 struct mthca_pd *pd,
120 					 struct mthca_srq *srq,
121 					 struct mthca_arbel_srq_context *context,
122 					 struct ib_udata *udata)
123 {
124 	struct mthca_ucontext *ucontext = rdma_udata_to_drv_context(
125 		udata, struct mthca_ucontext, ibucontext);
126 	int logsize, max;
127 
128 	memset(context, 0, sizeof *context);
129 
130 	/*
131 	 * Put max in a temporary variable to work around gcc bug
132 	 * triggered by ilog2() on sparc64.
133 	 */
134 	max = srq->max;
135 	logsize = ilog2(max);
136 	context->state_logsize_srqn = cpu_to_be32(logsize << 24 | srq->srqn);
137 	context->lkey = cpu_to_be32(srq->mr.ibmr.lkey);
138 	context->db_index = cpu_to_be32(srq->db_index);
139 	context->logstride_usrpage = cpu_to_be32((srq->wqe_shift - 4) << 29);
140 	if (udata)
141 		context->logstride_usrpage |= cpu_to_be32(ucontext->uar.index);
142 	else
143 		context->logstride_usrpage |= cpu_to_be32(dev->driver_uar.index);
144 	context->eq_pd = cpu_to_be32(MTHCA_EQ_ASYNC << 24 | pd->pd_num);
145 }
146 
147 static void mthca_free_srq_buf(struct mthca_dev *dev, struct mthca_srq *srq)
148 {
149 	mthca_buf_free(dev, srq->max << srq->wqe_shift, &srq->queue,
150 		       srq->is_direct, &srq->mr);
151 	kfree(srq->wrid);
152 }
153 
154 static int mthca_alloc_srq_buf(struct mthca_dev *dev, struct mthca_pd *pd,
155 			       struct mthca_srq *srq, struct ib_udata *udata)
156 {
157 	struct mthca_data_seg *scatter;
158 	void *wqe;
159 	int err;
160 	int i;
161 
162 	if (udata)
163 		return 0;
164 
165 	srq->wrid = kmalloc_array(srq->max, sizeof(u64), GFP_KERNEL);
166 	if (!srq->wrid)
167 		return -ENOMEM;
168 
169 	err = mthca_buf_alloc(dev, srq->max << srq->wqe_shift,
170 			      MTHCA_MAX_DIRECT_SRQ_SIZE,
171 			      &srq->queue, &srq->is_direct, pd, 1, &srq->mr);
172 	if (err) {
173 		kfree(srq->wrid);
174 		return err;
175 	}
176 
177 	/*
178 	 * Now initialize the SRQ buffer so that all of the WQEs are
179 	 * linked into the list of free WQEs.  In addition, set the
180 	 * scatter list L_Keys to the sentry value of 0x100.
181 	 */
182 	for (i = 0; i < srq->max; ++i) {
183 		struct mthca_next_seg *next;
184 
185 		next = wqe = get_wqe(srq, i);
186 
187 		if (i < srq->max - 1) {
188 			*wqe_to_link(wqe) = i + 1;
189 			next->nda_op = htonl(((i + 1) << srq->wqe_shift) | 1);
190 		} else {
191 			*wqe_to_link(wqe) = -1;
192 			next->nda_op = 0;
193 		}
194 
195 		for (scatter = wqe + sizeof (struct mthca_next_seg);
196 		     (void *) scatter < wqe + (1 << srq->wqe_shift);
197 		     ++scatter)
198 			scatter->lkey = cpu_to_be32(MTHCA_INVAL_LKEY);
199 	}
200 
201 	srq->last = get_wqe(srq, srq->max - 1);
202 
203 	return 0;
204 }
205 
206 int mthca_alloc_srq(struct mthca_dev *dev, struct mthca_pd *pd,
207 		    struct ib_srq_attr *attr, struct mthca_srq *srq,
208 		    struct ib_udata *udata)
209 {
210 	struct mthca_mailbox *mailbox;
211 	int ds;
212 	int err;
213 
214 	/* Sanity check SRQ size before proceeding */
215 	if (attr->max_wr  > dev->limits.max_srq_wqes ||
216 	    attr->max_sge > dev->limits.max_srq_sge)
217 		return -EINVAL;
218 
219 	srq->max      = attr->max_wr;
220 	srq->max_gs   = attr->max_sge;
221 	srq->counter  = 0;
222 
223 	if (mthca_is_memfree(dev))
224 		srq->max = roundup_pow_of_two(srq->max + 1);
225 	else
226 		srq->max = srq->max + 1;
227 
228 	ds = max(64UL,
229 		 roundup_pow_of_two(sizeof (struct mthca_next_seg) +
230 				    srq->max_gs * sizeof (struct mthca_data_seg)));
231 
232 	if (!mthca_is_memfree(dev) && (ds > dev->limits.max_desc_sz))
233 		return -EINVAL;
234 
235 	srq->wqe_shift = ilog2(ds);
236 
237 	srq->srqn = mthca_alloc(&dev->srq_table.alloc);
238 	if (srq->srqn == -1)
239 		return -ENOMEM;
240 
241 	if (mthca_is_memfree(dev)) {
242 		err = mthca_table_get(dev, dev->srq_table.table, srq->srqn);
243 		if (err)
244 			goto err_out;
245 
246 		if (!udata) {
247 			srq->db_index = mthca_alloc_db(dev, MTHCA_DB_TYPE_SRQ,
248 						       srq->srqn, &srq->db);
249 			if (srq->db_index < 0) {
250 				err = -ENOMEM;
251 				goto err_out_icm;
252 			}
253 		}
254 	}
255 
256 	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
257 	if (IS_ERR(mailbox)) {
258 		err = PTR_ERR(mailbox);
259 		goto err_out_db;
260 	}
261 
262 	err = mthca_alloc_srq_buf(dev, pd, srq, udata);
263 	if (err)
264 		goto err_out_mailbox;
265 
266 	spin_lock_init(&srq->lock);
267 	srq->refcount = 1;
268 	init_waitqueue_head(&srq->wait);
269 	mutex_init(&srq->mutex);
270 
271 	if (mthca_is_memfree(dev))
272 		mthca_arbel_init_srq_context(dev, pd, srq, mailbox->buf, udata);
273 	else
274 		mthca_tavor_init_srq_context(dev, pd, srq, mailbox->buf, udata);
275 
276 	err = mthca_SW2HW_SRQ(dev, mailbox, srq->srqn);
277 
278 	if (err) {
279 		mthca_warn(dev, "SW2HW_SRQ failed (%d)\n", err);
280 		goto err_out_free_buf;
281 	}
282 
283 	spin_lock_irq(&dev->srq_table.lock);
284 	if (mthca_array_set(&dev->srq_table.srq,
285 			    srq->srqn & (dev->limits.num_srqs - 1),
286 			    srq)) {
287 		spin_unlock_irq(&dev->srq_table.lock);
288 		goto err_out_free_srq;
289 	}
290 	spin_unlock_irq(&dev->srq_table.lock);
291 
292 	mthca_free_mailbox(dev, mailbox);
293 
294 	srq->first_free = 0;
295 	srq->last_free  = srq->max - 1;
296 
297 	attr->max_wr    = srq->max - 1;
298 	attr->max_sge   = srq->max_gs;
299 
300 	return 0;
301 
302 err_out_free_srq:
303 	err = mthca_HW2SW_SRQ(dev, mailbox, srq->srqn);
304 	if (err)
305 		mthca_warn(dev, "HW2SW_SRQ failed (%d)\n", err);
306 
307 err_out_free_buf:
308 	if (!udata)
309 		mthca_free_srq_buf(dev, srq);
310 
311 err_out_mailbox:
312 	mthca_free_mailbox(dev, mailbox);
313 
314 err_out_db:
315 	if (!udata && mthca_is_memfree(dev))
316 		mthca_free_db(dev, MTHCA_DB_TYPE_SRQ, srq->db_index);
317 
318 err_out_icm:
319 	mthca_table_put(dev, dev->srq_table.table, srq->srqn);
320 
321 err_out:
322 	mthca_free(&dev->srq_table.alloc, srq->srqn);
323 
324 	return err;
325 }
326 
327 static inline int get_srq_refcount(struct mthca_dev *dev, struct mthca_srq *srq)
328 {
329 	int c;
330 
331 	spin_lock_irq(&dev->srq_table.lock);
332 	c = srq->refcount;
333 	spin_unlock_irq(&dev->srq_table.lock);
334 
335 	return c;
336 }
337 
338 void mthca_free_srq(struct mthca_dev *dev, struct mthca_srq *srq)
339 {
340 	struct mthca_mailbox *mailbox;
341 	int err;
342 
343 	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
344 	if (IS_ERR(mailbox)) {
345 		mthca_warn(dev, "No memory for mailbox to free SRQ.\n");
346 		return;
347 	}
348 
349 	err = mthca_HW2SW_SRQ(dev, mailbox, srq->srqn);
350 	if (err)
351 		mthca_warn(dev, "HW2SW_SRQ failed (%d)\n", err);
352 
353 	spin_lock_irq(&dev->srq_table.lock);
354 	mthca_array_clear(&dev->srq_table.srq,
355 			  srq->srqn & (dev->limits.num_srqs - 1));
356 	--srq->refcount;
357 	spin_unlock_irq(&dev->srq_table.lock);
358 
359 	wait_event(srq->wait, !get_srq_refcount(dev, srq));
360 
361 	if (!srq->ibsrq.uobject) {
362 		mthca_free_srq_buf(dev, srq);
363 		if (mthca_is_memfree(dev))
364 			mthca_free_db(dev, MTHCA_DB_TYPE_SRQ, srq->db_index);
365 	}
366 
367 	mthca_table_put(dev, dev->srq_table.table, srq->srqn);
368 	mthca_free(&dev->srq_table.alloc, srq->srqn);
369 	mthca_free_mailbox(dev, mailbox);
370 }
371 
372 int mthca_modify_srq(struct ib_srq *ibsrq, struct ib_srq_attr *attr,
373 		     enum ib_srq_attr_mask attr_mask, struct ib_udata *udata)
374 {
375 	struct mthca_dev *dev = to_mdev(ibsrq->device);
376 	struct mthca_srq *srq = to_msrq(ibsrq);
377 	int ret = 0;
378 
379 	/* We don't support resizing SRQs (yet?) */
380 	if (attr_mask & IB_SRQ_MAX_WR)
381 		return -EINVAL;
382 
383 	if (attr_mask & IB_SRQ_LIMIT) {
384 		u32 max_wr = mthca_is_memfree(dev) ? srq->max - 1 : srq->max;
385 		if (attr->srq_limit > max_wr)
386 			return -EINVAL;
387 
388 		mutex_lock(&srq->mutex);
389 		ret = mthca_ARM_SRQ(dev, srq->srqn, attr->srq_limit);
390 		mutex_unlock(&srq->mutex);
391 	}
392 
393 	return ret;
394 }
395 
396 int mthca_query_srq(struct ib_srq *ibsrq, struct ib_srq_attr *srq_attr)
397 {
398 	struct mthca_dev *dev = to_mdev(ibsrq->device);
399 	struct mthca_srq *srq = to_msrq(ibsrq);
400 	struct mthca_mailbox *mailbox;
401 	struct mthca_arbel_srq_context *arbel_ctx;
402 	struct mthca_tavor_srq_context *tavor_ctx;
403 	int err;
404 
405 	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
406 	if (IS_ERR(mailbox))
407 		return PTR_ERR(mailbox);
408 
409 	err = mthca_QUERY_SRQ(dev, srq->srqn, mailbox);
410 	if (err)
411 		goto out;
412 
413 	if (mthca_is_memfree(dev)) {
414 		arbel_ctx = mailbox->buf;
415 		srq_attr->srq_limit = be16_to_cpu(arbel_ctx->limit_watermark);
416 	} else {
417 		tavor_ctx = mailbox->buf;
418 		srq_attr->srq_limit = be16_to_cpu(tavor_ctx->limit_watermark);
419 	}
420 
421 	srq_attr->max_wr  = srq->max - 1;
422 	srq_attr->max_sge = srq->max_gs;
423 
424 out:
425 	mthca_free_mailbox(dev, mailbox);
426 
427 	return err;
428 }
429 
430 void mthca_srq_event(struct mthca_dev *dev, u32 srqn,
431 		     enum ib_event_type event_type)
432 {
433 	struct mthca_srq *srq;
434 	struct ib_event event;
435 
436 	spin_lock(&dev->srq_table.lock);
437 	srq = mthca_array_get(&dev->srq_table.srq, srqn & (dev->limits.num_srqs - 1));
438 	if (srq)
439 		++srq->refcount;
440 	spin_unlock(&dev->srq_table.lock);
441 
442 	if (!srq) {
443 		mthca_warn(dev, "Async event for bogus SRQ %08x\n", srqn);
444 		return;
445 	}
446 
447 	if (!srq->ibsrq.event_handler)
448 		goto out;
449 
450 	event.device      = &dev->ib_dev;
451 	event.event       = event_type;
452 	event.element.srq = &srq->ibsrq;
453 	srq->ibsrq.event_handler(&event, srq->ibsrq.srq_context);
454 
455 out:
456 	spin_lock(&dev->srq_table.lock);
457 	if (!--srq->refcount)
458 		wake_up(&srq->wait);
459 	spin_unlock(&dev->srq_table.lock);
460 }
461 
462 /*
463  * This function must be called with IRQs disabled.
464  */
465 void mthca_free_srq_wqe(struct mthca_srq *srq, u32 wqe_addr)
466 {
467 	int ind;
468 	struct mthca_next_seg *last_free;
469 
470 	ind = wqe_addr >> srq->wqe_shift;
471 
472 	spin_lock(&srq->lock);
473 
474 	last_free = get_wqe(srq, srq->last_free);
475 	*wqe_to_link(last_free) = ind;
476 	last_free->nda_op = htonl((ind << srq->wqe_shift) | 1);
477 	*wqe_to_link(get_wqe(srq, ind)) = -1;
478 	srq->last_free = ind;
479 
480 	spin_unlock(&srq->lock);
481 }
482 
483 int mthca_tavor_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
484 			      const struct ib_recv_wr **bad_wr)
485 {
486 	struct mthca_dev *dev = to_mdev(ibsrq->device);
487 	struct mthca_srq *srq = to_msrq(ibsrq);
488 	unsigned long flags;
489 	int err = 0;
490 	int first_ind;
491 	int ind;
492 	int next_ind;
493 	int nreq;
494 	int i;
495 	void *wqe;
496 	void *prev_wqe;
497 
498 	spin_lock_irqsave(&srq->lock, flags);
499 
500 	first_ind = srq->first_free;
501 
502 	for (nreq = 0; wr; wr = wr->next) {
503 		ind       = srq->first_free;
504 		wqe       = get_wqe(srq, ind);
505 		next_ind  = *wqe_to_link(wqe);
506 
507 		if (unlikely(next_ind < 0)) {
508 			mthca_err(dev, "SRQ %06x full\n", srq->srqn);
509 			err = -ENOMEM;
510 			*bad_wr = wr;
511 			break;
512 		}
513 
514 		prev_wqe  = srq->last;
515 		srq->last = wqe;
516 
517 		((struct mthca_next_seg *) wqe)->ee_nds = 0;
518 		/* flags field will always remain 0 */
519 
520 		wqe += sizeof (struct mthca_next_seg);
521 
522 		if (unlikely(wr->num_sge > srq->max_gs)) {
523 			err = -EINVAL;
524 			*bad_wr = wr;
525 			srq->last = prev_wqe;
526 			break;
527 		}
528 
529 		for (i = 0; i < wr->num_sge; ++i) {
530 			mthca_set_data_seg(wqe, wr->sg_list + i);
531 			wqe += sizeof (struct mthca_data_seg);
532 		}
533 
534 		if (i < srq->max_gs)
535 			mthca_set_data_seg_inval(wqe);
536 
537 		((struct mthca_next_seg *) prev_wqe)->ee_nds =
538 			cpu_to_be32(MTHCA_NEXT_DBD);
539 
540 		srq->wrid[ind]  = wr->wr_id;
541 		srq->first_free = next_ind;
542 
543 		++nreq;
544 		if (unlikely(nreq == MTHCA_TAVOR_MAX_WQES_PER_RECV_DB)) {
545 			nreq = 0;
546 
547 			/*
548 			 * Make sure that descriptors are written
549 			 * before doorbell is rung.
550 			 */
551 			wmb();
552 
553 			mthca_write64(first_ind << srq->wqe_shift, srq->srqn << 8,
554 				      dev->kar + MTHCA_RECEIVE_DOORBELL,
555 				      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
556 
557 			first_ind = srq->first_free;
558 		}
559 	}
560 
561 	if (likely(nreq)) {
562 		/*
563 		 * Make sure that descriptors are written before
564 		 * doorbell is rung.
565 		 */
566 		wmb();
567 
568 		mthca_write64(first_ind << srq->wqe_shift, (srq->srqn << 8) | nreq,
569 			      dev->kar + MTHCA_RECEIVE_DOORBELL,
570 			      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
571 	}
572 
573 	/*
574 	 * Make sure doorbells don't leak out of SRQ spinlock and
575 	 * reach the HCA out of order:
576 	 */
577 	mmiowb();
578 
579 	spin_unlock_irqrestore(&srq->lock, flags);
580 	return err;
581 }
582 
583 int mthca_arbel_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
584 			      const struct ib_recv_wr **bad_wr)
585 {
586 	struct mthca_dev *dev = to_mdev(ibsrq->device);
587 	struct mthca_srq *srq = to_msrq(ibsrq);
588 	unsigned long flags;
589 	int err = 0;
590 	int ind;
591 	int next_ind;
592 	int nreq;
593 	int i;
594 	void *wqe;
595 
596 	spin_lock_irqsave(&srq->lock, flags);
597 
598 	for (nreq = 0; wr; ++nreq, wr = wr->next) {
599 		ind       = srq->first_free;
600 		wqe       = get_wqe(srq, ind);
601 		next_ind  = *wqe_to_link(wqe);
602 
603 		if (unlikely(next_ind < 0)) {
604 			mthca_err(dev, "SRQ %06x full\n", srq->srqn);
605 			err = -ENOMEM;
606 			*bad_wr = wr;
607 			break;
608 		}
609 
610 		((struct mthca_next_seg *) wqe)->ee_nds = 0;
611 		/* flags field will always remain 0 */
612 
613 		wqe += sizeof (struct mthca_next_seg);
614 
615 		if (unlikely(wr->num_sge > srq->max_gs)) {
616 			err = -EINVAL;
617 			*bad_wr = wr;
618 			break;
619 		}
620 
621 		for (i = 0; i < wr->num_sge; ++i) {
622 			mthca_set_data_seg(wqe, wr->sg_list + i);
623 			wqe += sizeof (struct mthca_data_seg);
624 		}
625 
626 		if (i < srq->max_gs)
627 			mthca_set_data_seg_inval(wqe);
628 
629 		srq->wrid[ind]  = wr->wr_id;
630 		srq->first_free = next_ind;
631 	}
632 
633 	if (likely(nreq)) {
634 		srq->counter += nreq;
635 
636 		/*
637 		 * Make sure that descriptors are written before
638 		 * we write doorbell record.
639 		 */
640 		wmb();
641 		*srq->db = cpu_to_be32(srq->counter);
642 	}
643 
644 	spin_unlock_irqrestore(&srq->lock, flags);
645 	return err;
646 }
647 
648 int mthca_max_srq_sge(struct mthca_dev *dev)
649 {
650 	if (mthca_is_memfree(dev))
651 		return dev->limits.max_sg;
652 
653 	/*
654 	 * SRQ allocations are based on powers of 2 for Tavor,
655 	 * (although they only need to be multiples of 16 bytes).
656 	 *
657 	 * Therefore, we need to base the max number of sg entries on
658 	 * the largest power of 2 descriptor size that is <= to the
659 	 * actual max WQE descriptor size, rather than return the
660 	 * max_sg value given by the firmware (which is based on WQE
661 	 * sizes as multiples of 16, not powers of 2).
662 	 *
663 	 * If SRQ implementation is changed for Tavor to be based on
664 	 * multiples of 16, the calculation below can be deleted and
665 	 * the FW max_sg value returned.
666 	 */
667 	return min_t(int, dev->limits.max_sg,
668 		     ((1 << (fls(dev->limits.max_desc_sz) - 1)) -
669 		      sizeof (struct mthca_next_seg)) /
670 		     sizeof (struct mthca_data_seg));
671 }
672 
673 int mthca_init_srq_table(struct mthca_dev *dev)
674 {
675 	int err;
676 
677 	if (!(dev->mthca_flags & MTHCA_FLAG_SRQ))
678 		return 0;
679 
680 	spin_lock_init(&dev->srq_table.lock);
681 
682 	err = mthca_alloc_init(&dev->srq_table.alloc,
683 			       dev->limits.num_srqs,
684 			       dev->limits.num_srqs - 1,
685 			       dev->limits.reserved_srqs);
686 	if (err)
687 		return err;
688 
689 	err = mthca_array_init(&dev->srq_table.srq,
690 			       dev->limits.num_srqs);
691 	if (err)
692 		mthca_alloc_cleanup(&dev->srq_table.alloc);
693 
694 	return err;
695 }
696 
697 void mthca_cleanup_srq_table(struct mthca_dev *dev)
698 {
699 	if (!(dev->mthca_flags & MTHCA_FLAG_SRQ))
700 		return;
701 
702 	mthca_array_cleanup(&dev->srq_table.srq, dev->limits.num_srqs);
703 	mthca_alloc_cleanup(&dev->srq_table.alloc);
704 }
705