mthca_srq.c revision 59fef3b1e96217c6e736372ff8cc95cbcca1b6aa
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 * $Id: mthca_srq.c 3047 2005-08-10 03:59:35Z roland $
33 */
34
35#include <linux/slab.h>
36#include <linux/string.h>
37
38#include "mthca_dev.h"
39#include "mthca_cmd.h"
40#include "mthca_memfree.h"
41#include "mthca_wqe.h"
42
43enum {
44	MTHCA_MAX_DIRECT_SRQ_SIZE = 4 * PAGE_SIZE
45};
46
47struct mthca_tavor_srq_context {
48	__be64 wqe_base_ds;	/* low 6 bits is descriptor size */
49	__be32 state_pd;
50	__be32 lkey;
51	__be32 uar;
52	__be16 limit_watermark;
53	__be16 wqe_cnt;
54	u32    reserved[2];
55};
56
57struct mthca_arbel_srq_context {
58	__be32 state_logsize_srqn;
59	__be32 lkey;
60	__be32 db_index;
61	__be32 logstride_usrpage;
62	__be64 wqe_base;
63	__be32 eq_pd;
64	__be16 limit_watermark;
65	__be16 wqe_cnt;
66	u16    reserved1;
67	__be16 wqe_counter;
68	u32    reserved2[3];
69};
70
71static void *get_wqe(struct mthca_srq *srq, int n)
72{
73	if (srq->is_direct)
74		return srq->queue.direct.buf + (n << srq->wqe_shift);
75	else
76		return srq->queue.page_list[(n << srq->wqe_shift) >> PAGE_SHIFT].buf +
77			((n << srq->wqe_shift) & (PAGE_SIZE - 1));
78}
79
80/*
81 * Return a pointer to the location within a WQE that we're using as a
82 * link when the WQE is in the free list.  We use the imm field
83 * because in the Tavor case, posting a WQE may overwrite the next
84 * segment of the previous WQE, but a receive WQE will never touch the
85 * imm field.  This avoids corrupting our free list if the previous
86 * WQE has already completed and been put on the free list when we
87 * post the next WQE.
88 */
89static inline int *wqe_to_link(void *wqe)
90{
91	return (int *) (wqe + offsetof(struct mthca_next_seg, imm));
92}
93
94static void mthca_tavor_init_srq_context(struct mthca_dev *dev,
95					 struct mthca_pd *pd,
96					 struct mthca_srq *srq,
97					 struct mthca_tavor_srq_context *context)
98{
99	memset(context, 0, sizeof *context);
100
101	context->wqe_base_ds = cpu_to_be64(1 << (srq->wqe_shift - 4));
102	context->state_pd    = cpu_to_be32(pd->pd_num);
103	context->lkey        = cpu_to_be32(srq->mr.ibmr.lkey);
104
105	if (pd->ibpd.uobject)
106		context->uar =
107			cpu_to_be32(to_mucontext(pd->ibpd.uobject->context)->uar.index);
108	else
109		context->uar = cpu_to_be32(dev->driver_uar.index);
110}
111
112static void mthca_arbel_init_srq_context(struct mthca_dev *dev,
113					 struct mthca_pd *pd,
114					 struct mthca_srq *srq,
115					 struct mthca_arbel_srq_context *context)
116{
117	int logsize;
118
119	memset(context, 0, sizeof *context);
120
121	logsize = long_log2(srq->max) + srq->wqe_shift;
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
134static 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
141static 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		wqe = get_wqe(srq, i);
171
172		*wqe_to_link(wqe) = i < srq->max - 1 ? i + 1 : -1;
173
174		for (scatter = wqe + sizeof (struct mthca_next_seg);
175		     (void *) scatter < wqe + (1 << srq->wqe_shift);
176		     ++scatter)
177			scatter->lkey = cpu_to_be32(MTHCA_INVAL_LKEY);
178	}
179
180	srq->last = get_wqe(srq, srq->max - 1);
181
182	return 0;
183}
184
185int mthca_alloc_srq(struct mthca_dev *dev, struct mthca_pd *pd,
186		    struct ib_srq_attr *attr, struct mthca_srq *srq)
187{
188	struct mthca_mailbox *mailbox;
189	u8 status;
190	int ds;
191	int err;
192
193	/* Sanity check SRQ size before proceeding */
194	if (attr->max_wr  > dev->limits.max_srq_wqes ||
195	    attr->max_sge > dev->limits.max_srq_sge)
196		return -EINVAL;
197
198	srq->max      = attr->max_wr;
199	srq->max_gs   = attr->max_sge;
200	srq->counter  = 0;
201
202	if (mthca_is_memfree(dev))
203		srq->max = roundup_pow_of_two(srq->max + 1);
204
205	ds = max(64UL,
206		 roundup_pow_of_two(sizeof (struct mthca_next_seg) +
207				    srq->max_gs * sizeof (struct mthca_data_seg)));
208
209	if (!mthca_is_memfree(dev) && (ds > dev->limits.max_desc_sz))
210		return -EINVAL;
211
212	srq->wqe_shift = long_log2(ds);
213
214	srq->srqn = mthca_alloc(&dev->srq_table.alloc);
215	if (srq->srqn == -1)
216		return -ENOMEM;
217
218	if (mthca_is_memfree(dev)) {
219		err = mthca_table_get(dev, dev->srq_table.table, srq->srqn);
220		if (err)
221			goto err_out;
222
223		if (!pd->ibpd.uobject) {
224			srq->db_index = mthca_alloc_db(dev, MTHCA_DB_TYPE_SRQ,
225						       srq->srqn, &srq->db);
226			if (srq->db_index < 0) {
227				err = -ENOMEM;
228				goto err_out_icm;
229			}
230		}
231	}
232
233	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
234	if (IS_ERR(mailbox)) {
235		err = PTR_ERR(mailbox);
236		goto err_out_db;
237	}
238
239	err = mthca_alloc_srq_buf(dev, pd, srq);
240	if (err)
241		goto err_out_mailbox;
242
243	spin_lock_init(&srq->lock);
244	atomic_set(&srq->refcount, 1);
245	init_waitqueue_head(&srq->wait);
246
247	if (mthca_is_memfree(dev))
248		mthca_arbel_init_srq_context(dev, pd, srq, mailbox->buf);
249	else
250		mthca_tavor_init_srq_context(dev, pd, srq, mailbox->buf);
251
252	err = mthca_SW2HW_SRQ(dev, mailbox, srq->srqn, &status);
253
254	if (err) {
255		mthca_warn(dev, "SW2HW_SRQ failed (%d)\n", err);
256		goto err_out_free_buf;
257	}
258	if (status) {
259		mthca_warn(dev, "SW2HW_SRQ returned status 0x%02x\n",
260			   status);
261		err = -EINVAL;
262		goto err_out_free_buf;
263	}
264
265	spin_lock_irq(&dev->srq_table.lock);
266	if (mthca_array_set(&dev->srq_table.srq,
267			    srq->srqn & (dev->limits.num_srqs - 1),
268			    srq)) {
269		spin_unlock_irq(&dev->srq_table.lock);
270		goto err_out_free_srq;
271	}
272	spin_unlock_irq(&dev->srq_table.lock);
273
274	mthca_free_mailbox(dev, mailbox);
275
276	srq->first_free = 0;
277	srq->last_free  = srq->max - 1;
278
279	attr->max_wr    = (mthca_is_memfree(dev)) ? srq->max - 1 : srq->max;
280	attr->max_sge   = srq->max_gs;
281
282	return 0;
283
284err_out_free_srq:
285	err = mthca_HW2SW_SRQ(dev, mailbox, srq->srqn, &status);
286	if (err)
287		mthca_warn(dev, "HW2SW_SRQ failed (%d)\n", err);
288	else if (status)
289		mthca_warn(dev, "HW2SW_SRQ returned status 0x%02x\n", status);
290
291err_out_free_buf:
292	if (!pd->ibpd.uobject)
293		mthca_free_srq_buf(dev, srq);
294
295err_out_mailbox:
296	mthca_free_mailbox(dev, mailbox);
297
298err_out_db:
299	if (!pd->ibpd.uobject && mthca_is_memfree(dev))
300		mthca_free_db(dev, MTHCA_DB_TYPE_SRQ, srq->db_index);
301
302err_out_icm:
303	mthca_table_put(dev, dev->srq_table.table, srq->srqn);
304
305err_out:
306	mthca_free(&dev->srq_table.alloc, srq->srqn);
307
308	return err;
309}
310
311void mthca_free_srq(struct mthca_dev *dev, struct mthca_srq *srq)
312{
313	struct mthca_mailbox *mailbox;
314	int err;
315	u8 status;
316
317	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
318	if (IS_ERR(mailbox)) {
319		mthca_warn(dev, "No memory for mailbox to free SRQ.\n");
320		return;
321	}
322
323	err = mthca_HW2SW_SRQ(dev, mailbox, srq->srqn, &status);
324	if (err)
325		mthca_warn(dev, "HW2SW_SRQ failed (%d)\n", err);
326	else if (status)
327		mthca_warn(dev, "HW2SW_SRQ returned status 0x%02x\n", status);
328
329	spin_lock_irq(&dev->srq_table.lock);
330	mthca_array_clear(&dev->srq_table.srq,
331			  srq->srqn & (dev->limits.num_srqs - 1));
332	spin_unlock_irq(&dev->srq_table.lock);
333
334	atomic_dec(&srq->refcount);
335	wait_event(srq->wait, !atomic_read(&srq->refcount));
336
337	if (!srq->ibsrq.uobject) {
338		mthca_free_srq_buf(dev, srq);
339		if (mthca_is_memfree(dev))
340			mthca_free_db(dev, MTHCA_DB_TYPE_SRQ, srq->db_index);
341	}
342
343	mthca_table_put(dev, dev->srq_table.table, srq->srqn);
344	mthca_free(&dev->srq_table.alloc, srq->srqn);
345	mthca_free_mailbox(dev, mailbox);
346}
347
348int mthca_modify_srq(struct ib_srq *ibsrq, struct ib_srq_attr *attr,
349		     enum ib_srq_attr_mask attr_mask)
350{
351	struct mthca_dev *dev = to_mdev(ibsrq->device);
352	struct mthca_srq *srq = to_msrq(ibsrq);
353	int ret;
354	u8 status;
355
356	/* We don't support resizing SRQs (yet?) */
357	if (attr_mask & IB_SRQ_MAX_WR)
358		return -EINVAL;
359
360	if (attr_mask & IB_SRQ_LIMIT) {
361		if (attr->srq_limit > srq->max)
362			return -EINVAL;
363		ret = mthca_ARM_SRQ(dev, srq->srqn, attr->srq_limit, &status);
364		if (ret)
365			return ret;
366		if (status)
367			return -EINVAL;
368	}
369
370	return 0;
371}
372
373int mthca_query_srq(struct ib_srq *ibsrq, struct ib_srq_attr *srq_attr)
374{
375	struct mthca_dev *dev = to_mdev(ibsrq->device);
376	struct mthca_srq *srq = to_msrq(ibsrq);
377	struct mthca_mailbox *mailbox;
378	struct mthca_arbel_srq_context *arbel_ctx;
379	struct mthca_tavor_srq_context *tavor_ctx;
380	u8 status;
381	int err;
382
383	mailbox = mthca_alloc_mailbox(dev, GFP_KERNEL);
384	if (IS_ERR(mailbox))
385		return PTR_ERR(mailbox);
386
387	err = mthca_QUERY_SRQ(dev, srq->srqn, mailbox, &status);
388	if (err)
389		goto out;
390
391	if (mthca_is_memfree(dev)) {
392		arbel_ctx = mailbox->buf;
393		srq_attr->srq_limit = be16_to_cpu(arbel_ctx->limit_watermark);
394	} else {
395		tavor_ctx = mailbox->buf;
396		srq_attr->srq_limit = be16_to_cpu(tavor_ctx->limit_watermark);
397	}
398
399	srq_attr->max_wr  = (mthca_is_memfree(dev)) ? srq->max - 1 : srq->max;
400	srq_attr->max_sge = srq->max_gs;
401
402out:
403	mthca_free_mailbox(dev, mailbox);
404
405	return err;
406}
407
408void mthca_srq_event(struct mthca_dev *dev, u32 srqn,
409		     enum ib_event_type event_type)
410{
411	struct mthca_srq *srq;
412	struct ib_event event;
413
414	spin_lock(&dev->srq_table.lock);
415	srq = mthca_array_get(&dev->srq_table.srq, srqn & (dev->limits.num_srqs - 1));
416	if (srq)
417		atomic_inc(&srq->refcount);
418	spin_unlock(&dev->srq_table.lock);
419
420	if (!srq) {
421		mthca_warn(dev, "Async event for bogus SRQ %08x\n", srqn);
422		return;
423	}
424
425	if (!srq->ibsrq.event_handler)
426		goto out;
427
428	event.device      = &dev->ib_dev;
429	event.event       = event_type;
430	event.element.srq = &srq->ibsrq;
431	srq->ibsrq.event_handler(&event, srq->ibsrq.srq_context);
432
433out:
434	if (atomic_dec_and_test(&srq->refcount))
435		wake_up(&srq->wait);
436}
437
438/*
439 * This function must be called with IRQs disabled.
440 */
441void mthca_free_srq_wqe(struct mthca_srq *srq, u32 wqe_addr)
442{
443	int ind;
444
445	ind = wqe_addr >> srq->wqe_shift;
446
447	spin_lock(&srq->lock);
448
449	if (likely(srq->first_free >= 0))
450		*wqe_to_link(get_wqe(srq, srq->last_free)) = ind;
451	else
452		srq->first_free = ind;
453
454	*wqe_to_link(get_wqe(srq, ind)) = -1;
455	srq->last_free = ind;
456
457	spin_unlock(&srq->lock);
458}
459
460int mthca_tavor_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
461			      struct ib_recv_wr **bad_wr)
462{
463	struct mthca_dev *dev = to_mdev(ibsrq->device);
464	struct mthca_srq *srq = to_msrq(ibsrq);
465	__be32 doorbell[2];
466	unsigned long flags;
467	int err = 0;
468	int first_ind;
469	int ind;
470	int next_ind;
471	int nreq;
472	int i;
473	void *wqe;
474	void *prev_wqe;
475
476	spin_lock_irqsave(&srq->lock, flags);
477
478	first_ind = srq->first_free;
479
480	for (nreq = 0; wr; ++nreq, wr = wr->next) {
481		if (unlikely(nreq == MTHCA_TAVOR_MAX_WQES_PER_RECV_DB)) {
482			nreq = 0;
483
484			doorbell[0] = cpu_to_be32(first_ind << srq->wqe_shift);
485			doorbell[1] = cpu_to_be32(srq->srqn << 8);
486
487			/*
488			 * Make sure that descriptors are written
489			 * before doorbell is rung.
490			 */
491			wmb();
492
493			mthca_write64(doorbell,
494				      dev->kar + MTHCA_RECEIVE_DOORBELL,
495				      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
496
497			first_ind = srq->first_free;
498		}
499
500		ind = srq->first_free;
501
502		if (ind < 0) {
503			mthca_err(dev, "SRQ %06x full\n", srq->srqn);
504			err = -ENOMEM;
505			*bad_wr = wr;
506			break;
507		}
508
509		wqe       = get_wqe(srq, ind);
510		next_ind  = *wqe_to_link(wqe);
511
512		if (next_ind < 0) {
513			mthca_err(dev, "SRQ %06x full\n", srq->srqn);
514			err = -ENOMEM;
515			*bad_wr = wr;
516			break;
517		}
518
519		prev_wqe  = srq->last;
520		srq->last = wqe;
521
522		((struct mthca_next_seg *) wqe)->nda_op = 0;
523		((struct mthca_next_seg *) wqe)->ee_nds = 0;
524		/* flags field will always remain 0 */
525
526		wqe += sizeof (struct mthca_next_seg);
527
528		if (unlikely(wr->num_sge > srq->max_gs)) {
529			err = -EINVAL;
530			*bad_wr = wr;
531			srq->last = prev_wqe;
532			break;
533		}
534
535		for (i = 0; i < wr->num_sge; ++i) {
536			((struct mthca_data_seg *) wqe)->byte_count =
537				cpu_to_be32(wr->sg_list[i].length);
538			((struct mthca_data_seg *) wqe)->lkey =
539				cpu_to_be32(wr->sg_list[i].lkey);
540			((struct mthca_data_seg *) wqe)->addr =
541				cpu_to_be64(wr->sg_list[i].addr);
542			wqe += sizeof (struct mthca_data_seg);
543		}
544
545		if (i < srq->max_gs) {
546			((struct mthca_data_seg *) wqe)->byte_count = 0;
547			((struct mthca_data_seg *) wqe)->lkey = cpu_to_be32(MTHCA_INVAL_LKEY);
548			((struct mthca_data_seg *) wqe)->addr = 0;
549		}
550
551		((struct mthca_next_seg *) prev_wqe)->nda_op =
552			cpu_to_be32((ind << srq->wqe_shift) | 1);
553		wmb();
554		((struct mthca_next_seg *) prev_wqe)->ee_nds =
555			cpu_to_be32(MTHCA_NEXT_DBD);
556
557		srq->wrid[ind]  = wr->wr_id;
558		srq->first_free = next_ind;
559	}
560
561	if (likely(nreq)) {
562		doorbell[0] = cpu_to_be32(first_ind << srq->wqe_shift);
563		doorbell[1] = cpu_to_be32((srq->srqn << 8) | nreq);
564
565		/*
566		 * Make sure that descriptors are written before
567		 * doorbell is rung.
568		 */
569		wmb();
570
571		mthca_write64(doorbell,
572			      dev->kar + MTHCA_RECEIVE_DOORBELL,
573			      MTHCA_GET_DOORBELL_LOCK(&dev->doorbell_lock));
574	}
575
576	spin_unlock_irqrestore(&srq->lock, flags);
577	return err;
578}
579
580int mthca_arbel_post_srq_recv(struct ib_srq *ibsrq, struct ib_recv_wr *wr,
581			      struct ib_recv_wr **bad_wr)
582{
583	struct mthca_dev *dev = to_mdev(ibsrq->device);
584	struct mthca_srq *srq = to_msrq(ibsrq);
585	unsigned long flags;
586	int err = 0;
587	int ind;
588	int next_ind;
589	int nreq;
590	int i;
591	void *wqe;
592
593	spin_lock_irqsave(&srq->lock, flags);
594
595	for (nreq = 0; wr; ++nreq, wr = wr->next) {
596		ind = srq->first_free;
597
598		if (ind < 0) {
599			mthca_err(dev, "SRQ %06x full\n", srq->srqn);
600			err = -ENOMEM;
601			*bad_wr = wr;
602			break;
603		}
604
605		wqe       = get_wqe(srq, ind);
606		next_ind  = *wqe_to_link(wqe);
607
608		if (next_ind < 0) {
609			mthca_err(dev, "SRQ %06x full\n", srq->srqn);
610			err = -ENOMEM;
611			*bad_wr = wr;
612			break;
613		}
614
615		((struct mthca_next_seg *) wqe)->nda_op =
616			cpu_to_be32((next_ind << srq->wqe_shift) | 1);
617		((struct mthca_next_seg *) wqe)->ee_nds = 0;
618		/* flags field will always remain 0 */
619
620		wqe += sizeof (struct mthca_next_seg);
621
622		if (unlikely(wr->num_sge > srq->max_gs)) {
623			err = -EINVAL;
624			*bad_wr = wr;
625			break;
626		}
627
628		for (i = 0; i < wr->num_sge; ++i) {
629			((struct mthca_data_seg *) wqe)->byte_count =
630				cpu_to_be32(wr->sg_list[i].length);
631			((struct mthca_data_seg *) wqe)->lkey =
632				cpu_to_be32(wr->sg_list[i].lkey);
633			((struct mthca_data_seg *) wqe)->addr =
634				cpu_to_be64(wr->sg_list[i].addr);
635			wqe += sizeof (struct mthca_data_seg);
636		}
637
638		if (i < srq->max_gs) {
639			((struct mthca_data_seg *) wqe)->byte_count = 0;
640			((struct mthca_data_seg *) wqe)->lkey = cpu_to_be32(MTHCA_INVAL_LKEY);
641			((struct mthca_data_seg *) wqe)->addr = 0;
642		}
643
644		srq->wrid[ind]  = wr->wr_id;
645		srq->first_free = next_ind;
646	}
647
648	if (likely(nreq)) {
649		srq->counter += nreq;
650
651		/*
652		 * Make sure that descriptors are written before
653		 * we write doorbell record.
654		 */
655		wmb();
656		*srq->db = cpu_to_be32(srq->counter);
657	}
658
659	spin_unlock_irqrestore(&srq->lock, flags);
660	return err;
661}
662
663int mthca_max_srq_sge(struct mthca_dev *dev)
664{
665	if (mthca_is_memfree(dev))
666		return dev->limits.max_sg;
667
668	/*
669	 * SRQ allocations are based on powers of 2 for Tavor,
670	 * (although they only need to be multiples of 16 bytes).
671	 *
672	 * Therefore, we need to base the max number of sg entries on
673	 * the largest power of 2 descriptor size that is <= to the
674	 * actual max WQE descriptor size, rather than return the
675	 * max_sg value given by the firmware (which is based on WQE
676	 * sizes as multiples of 16, not powers of 2).
677	 *
678	 * If SRQ implementation is changed for Tavor to be based on
679	 * multiples of 16, the calculation below can be deleted and
680	 * the FW max_sg value returned.
681	 */
682	return min_t(int, dev->limits.max_sg,
683		     ((1 << (fls(dev->limits.max_desc_sz) - 1)) -
684		      sizeof (struct mthca_next_seg)) /
685		     sizeof (struct mthca_data_seg));
686}
687
688int __devinit mthca_init_srq_table(struct mthca_dev *dev)
689{
690	int err;
691
692	if (!(dev->mthca_flags & MTHCA_FLAG_SRQ))
693		return 0;
694
695	spin_lock_init(&dev->srq_table.lock);
696
697	err = mthca_alloc_init(&dev->srq_table.alloc,
698			       dev->limits.num_srqs,
699			       dev->limits.num_srqs - 1,
700			       dev->limits.reserved_srqs);
701	if (err)
702		return err;
703
704	err = mthca_array_init(&dev->srq_table.srq,
705			       dev->limits.num_srqs);
706	if (err)
707		mthca_alloc_cleanup(&dev->srq_table.alloc);
708
709	return err;
710}
711
712void mthca_cleanup_srq_table(struct mthca_dev *dev)
713{
714	if (!(dev->mthca_flags & MTHCA_FLAG_SRQ))
715		return;
716
717	mthca_array_cleanup(&dev->srq_table.srq, dev->limits.num_srqs);
718	mthca_alloc_cleanup(&dev->srq_table.alloc);
719}
720