aboutsummaryrefslogtreecommitdiff
path: root/drivers/infiniband/hw/ipath/ipath_user_sdma.c
blob: 7bff4b9baa0a83ada20f29abceea8d90333f0026 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
/*
 * Copyright (c) 2007, 2008 QLogic Corporation. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/dmapool.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/uio.h>
#include <linux/rbtree.h>
#include <linux/spinlock.h>
#include <linux/delay.h>

#include "ipath_kernel.h"
#include "ipath_user_sdma.h"

/* minimum size of header */
#define IPATH_USER_SDMA_MIN_HEADER_LENGTH	64
/* expected size of headers (for dma_pool) */
#define IPATH_USER_SDMA_EXP_HEADER_LENGTH	64
/* length mask in PBC (lower 11 bits) */
#define IPATH_PBC_LENGTH_MASK			((1 << 11) - 1)

struct ipath_user_sdma_pkt {
	u8 naddr;		/* dimension of addr (1..3) ... */
	u32 counter;		/* sdma pkts queued counter for this entry */
	u64 added;		/* global descq number of entries */

	struct {
		u32 offset;			/* offset for kvaddr, addr */
		u32 length;			/* length in page */
		u8  put_page;			/* should we put_page? */
		u8  dma_mapped;			/* is page dma_mapped? */
		struct page *page;		/* may be NULL (coherent mem) */
		void *kvaddr;			/* FIXME: only for pio hack */
		dma_addr_t addr;
	} addr[4];   /* max pages, any more and we coalesce */
	struct list_head list;	/* list element */
};

struct ipath_user_sdma_queue {
	/*
	 * pkts sent to dma engine are queued on this
	 * list head.  the type of the elements of this
	 * list are struct ipath_user_sdma_pkt...
	 */
	struct list_head sent;

	/* headers with expected length are allocated from here... */
	char header_cache_name[64];
	struct dma_pool *header_cache;

	/* packets are allocated from the slab cache... */
	char pkt_slab_name[64];
	struct kmem_cache *pkt_slab;

	/* as packets go on the queued queue, they are counted... */
	u32 counter;
	u32 sent_counter;

	/* dma page table */
	struct rb_root dma_pages_root;

	/* protect everything above... */
	struct mutex lock;
};

struct ipath_user_sdma_queue *
ipath_user_sdma_queue_create(struct device *dev, int unit, int port, int sport)
{
	struct ipath_user_sdma_queue *pq =
		kmalloc(sizeof(struct ipath_user_sdma_queue), GFP_KERNEL);

	if (!pq)
		goto done;

	pq->counter = 0;
	pq->sent_counter = 0;
	INIT_LIST_HEAD(&pq->sent);

	mutex_init(&pq->lock);

	snprintf(pq->pkt_slab_name, sizeof(pq->pkt_slab_name),
		 "ipath-user-sdma-pkts-%u-%02u.%02u", unit, port, sport);
	pq->pkt_slab = kmem_cache_create(pq->pkt_slab_name,
					 sizeof(struct ipath_user_sdma_pkt),
					 0, 0, NULL);

	if (!pq->pkt_slab)
		goto err_kfree;

	snprintf(pq->header_cache_name, sizeof(pq->header_cache_name),
		 "ipath-user-sdma-headers-%u-%02u.%02u", unit, port, sport);
	pq->header_cache = dma_pool_create(pq->header_cache_name,
					   dev,
					   IPATH_USER_SDMA_EXP_HEADER_LENGTH,
					   4, 0);
	if (!pq->header_cache)
		goto err_slab;

	pq->dma_pages_root = RB_ROOT;

	goto done;

err_slab:
	kmem_cache_destroy(pq->pkt_slab);
err_kfree:
	kfree(pq);
	pq = NULL;

done:
	return pq;
}

static void ipath_user_sdma_init_frag(struct ipath_user_sdma_pkt *pkt,
				      int i, size_t offset, size_t len,
				      int put_page, int dma_mapped,
				      struct page *page,
				      void *kvaddr, dma_addr_t dma_addr)
{
	pkt->addr[i].offset = offset;
	pkt->addr[i].length = len;
	pkt->addr[i].put_page = put_page;
	pkt->addr[i].dma_mapped = dma_mapped;
	pkt->addr[i].page = page;
	pkt->addr[i].kvaddr = kvaddr;
	pkt->addr[i].addr = dma_addr;
}

static void ipath_user_sdma_init_header(struct ipath_user_sdma_pkt *pkt,
					u32 counter, size_t offset,
					size_t len, int dma_mapped,
					struct page *page,
					void *kvaddr, dma_addr_t dma_addr)
{
	pkt->naddr = 1;
	pkt->counter = counter;
	ipath_user_sdma_init_frag(pkt, 0, offset, len, 0, dma_mapped, page,
				  kvaddr, dma_addr);
}

/* we've too many pages in the iovec, coalesce to a single page */
static int ipath_user_sdma_coalesce(const struct ipath_devdata *dd,
				    struct ipath_user_sdma_pkt *pkt,
				    const struct iovec *iov,
				    unsigned long niov) {
	int ret = 0;
	struct page *page = alloc_page(GFP_KERNEL);
	void *mpage_save;
	char *mpage;
	int i;
	int len = 0;
	dma_addr_t dma_addr;

	if (!page) {
		ret = -ENOMEM;
		goto done;
	}

	mpage = kmap(page);
	mpage_save = mpage;
	for (i = 0; i < niov; i++) {
		int cfur;

		cfur = copy_from_user(mpage,
				      iov[i].iov_base, iov[i].iov_len);
		if (cfur) {
			ret = -EFAULT;
			goto free_unmap;
		}

		mpage += iov[i].iov_len;
		len += iov[i].iov_len;
	}

	dma_addr = dma_map_page(&dd->pcidev->dev, page, 0, len,
				DMA_TO_DEVICE);
	if (dma_mapping_error(&dd->pcidev->dev, dma_addr)) {
		ret = -ENOMEM;
		goto free_unmap;
	}

	ipath_user_sdma_init_frag(pkt, 1, 0, len, 0, 1, page, mpage_save,
				  dma_addr);
	pkt->naddr = 2;

	goto done;

free_unmap:
	kunmap(page);
	__free_page(page);
done:
	return ret;
}

/* how many pages in this iovec element? */
static int ipath_user_sdma_num_pages(const struct iovec *iov)
{
	const unsigned long addr  = (unsigned long) iov->iov_base;
	const unsigned long  len  = iov->iov_len;
	const unsigned long spage = addr & PAGE_MASK;
	const unsigned long epage = (addr + len - 1) & PAGE_MASK;

	return 1 + ((epage - spage) >> PAGE_SHIFT);
}

/* truncate length to page boundry */
static int ipath_user_sdma_page_length(unsigned long addr, unsigned long len)
{
	const unsigned long offset = addr & ~PAGE_MASK;

	return ((offset + len) > PAGE_SIZE) ? (PAGE_SIZE - offset) : len;
}

static void ipath_user_sdma_free_pkt_frag(struct device *dev,
					  struct ipath_user_sdma_queue *pq,
					  struct ipath_user_sdma_pkt *pkt,
					  int frag)
{
	const int i = frag;

	if (pkt->addr[i].page) {
		if (pkt->addr[i].dma_mapped)
			dma_unmap_page(dev,
				       pkt->addr[i].addr,
				       pkt->addr[i].length,
				       DMA_TO_DEVICE);

		if (pkt->addr[i].kvaddr)
			kunmap(pkt->addr[i].page);

		if (pkt->addr[i].put_page)
			put_page(pkt->addr[i].page);
		else
			__free_page(pkt->addr[i].page);
	} else if (pkt->addr[i].kvaddr)
		/* free coherent mem from cache... */
		dma_pool_free(pq->header_cache,
			      pkt->addr[i].kvaddr, pkt->addr[i].addr);
}

/* return number of pages pinned... */
static int ipath_user_sdma_pin_pages(const struct ipath_devdata *dd,
				     struct ipath_user_sdma_pkt *pkt,
				     unsigned long addr, int tlen, int npages)
{
	struct page *pages[2];
	int j;
	int ret;

	ret = get_user_pages(current, current->mm, addr,
			     npages, 0, 1, pages, NULL);

	if (ret != npages) {
		int i;

		for (i = 0; i < ret; i++)
			put_page(pages[i]);

		ret = -ENOMEM;
		goto done;
	}

	for (j = 0; j < npages; j++) {
		/* map the pages... */
		const int flen =
			ipath_user_sdma_page_length(addr, tlen);
		dma_addr_t dma_addr =
			dma_map_page(&dd->pcidev->dev,
				     pages[j], 0, flen, DMA_TO_DEVICE);
		unsigned long fofs = addr & ~PAGE_MASK;

		if (dma_mapping_error(&dd->pcidev->dev, dma_addr)) {
			ret = -ENOMEM;
			goto done;
		}

		ipath_user_sdma_init_frag(pkt, pkt->naddr, fofs, flen, 1, 1,
					  pages[j], kmap(pages[j]),
					  dma_addr);

		pkt->naddr++;
		addr += flen;
		tlen -= flen;
	}

done:
	return ret;
}

static int ipath_user_sdma_pin_pkt(const struct ipath_devdata *dd,
				   struct ipath_user_sdma_queue *pq,
				   struct ipath_user_sdma_pkt *pkt,
				   const struct iovec *iov,
				   unsigned long niov)
{
	int ret = 0;
	unsigned long idx;

	for (idx = 0; idx < niov; idx++) {
		const int npages = ipath_user_sdma_num_pages(iov + idx);
		const unsigned long addr = (unsigned long) iov[idx].iov_base;

		ret = ipath_user_sdma_pin_pages(dd, pkt,
						addr, iov[idx].iov_len,
						npages);
		if (ret < 0)
			goto free_pkt;
	}

	goto done;

free_pkt:
	for (idx = 0; idx < pkt->naddr; idx++)
		ipath_user_sdma_free_pkt_frag(&dd->pcidev->dev, pq, pkt, idx);

done:
	return ret;
}

static int ipath_user_sdma_init_payload(const struct ipath_devdata *dd,
					struct ipath_user_sdma_queue *pq,
					struct ipath_user_sdma_pkt *pkt,
					const struct iovec *iov,
					unsigned long niov, int npages)
{
	int ret = 0;

	if (npages >= ARRAY_SIZE(pkt->addr))
		ret = ipath_user_sdma_coalesce(dd, pkt, iov, niov);
	else
		ret = ipath_user_sdma_pin_pkt(dd, pq, pkt, iov, niov);

	return ret;
}

/* free a packet list -- return counter value of last packet */
static void ipath_user_sdma_free_pkt_list(struct device *dev,
					  struct ipath_user_sdma_queue *pq,
					  struct list_head *list)
{
	struct ipath_user_sdma_pkt *pkt, *pkt_next;

	list_for_each_entry_safe(pkt, pkt_next, list, list) {
		int i;

		for (i = 0; i < pkt->naddr; i++)
			ipath_user_sdma_free_pkt_frag(dev, pq, pkt, i);

		kmem_cache_free(pq->pkt_slab, pkt);
	}
}

/*
 * copy headers, coalesce etc -- pq->lock must be held
 *
 * we queue all the packets to list, returning the
 * number of bytes total.  list must be empty initially,
 * as, if there is an error we clean it...
 */
static int ipath_user_sdma_queue_pkts(const struct ipath_devdata *dd,
				      struct ipath_user_sdma_queue *pq,
				      struct list_head *list,
				      const struct iovec *iov,
				      unsigned long niov,
				      int maxpkts)
{
	unsigned long idx = 0;
	int ret = 0;
	int npkts = 0;
	struct page *page = NULL;
	__le32 *pbc;
	dma_addr_t dma_addr;
	struct ipath_user_sdma_pkt *pkt = NULL;
	size_t len;
	size_t nw;
	u32 counter = pq->counter;
	int dma_mapped = 0;

	while (idx < niov && npkts < maxpkts) {
		const unsigned long addr = (unsigned long) iov[idx].iov_base;
		const unsigned long idx_save = idx;
		unsigned pktnw;
		unsigned pktnwc;
		int nfrags = 0;
		int npages = 0;
		int cfur;

		dma_mapped = 0;
		len = iov[idx].iov_len;
		nw = len >> 2;
		page = NULL;

		pkt = kmem_cache_alloc(pq->pkt_slab, GFP_KERNEL);
		if (!pkt) {
			ret = -ENOMEM;
			goto free_list;
		}

		if (len < IPATH_USER_SDMA_MIN_HEADER_LENGTH ||
		    len > PAGE_SIZE || len & 3 || addr & 3) {
			ret = -EINVAL;
			goto free_pkt;
		}

		if (len == IPATH_USER_SDMA_EXP_HEADER_LENGTH)
			pbc = dma_pool_alloc(pq->header_cache, GFP_KERNEL,
					     &dma_addr);
		else
			pbc = NULL;

		if (!pbc) {
			page = alloc_page(GFP_KERNEL);
			if (!page) {
				ret = -ENOMEM;
				goto free_pkt;
			}
			pbc = kmap(page);
		}

		cfur = copy_from_user(pbc, iov[idx].iov_base, len);
		if (cfur) {
			ret = -EFAULT;
			goto free_pbc;
		}

		/*
		 * this assignment is a bit strange.  it's because the
		 * the pbc counts the number of 32 bit words in the full
		 * packet _except_ the first word of the pbc itself...
		 */
		pktnwc = nw - 1;

		/*
		 * pktnw computation yields the number of 32 bit words
		 * that the caller has indicated in the PBC.  note that
		 * this is one less than the total number of words that
		 * goes to the send DMA engine as the first 32 bit word
		 * of the PBC itself is not counted.  Armed with this count,
		 * we can verify that the packet is consistent with the
		 * iovec lengths.
		 */
		pktnw = le32_to_cpu(*pbc) & IPATH_PBC_LENGTH_MASK;
		if (pktnw < pktnwc || pktnw > pktnwc + (PAGE_SIZE >> 2)) {
			ret = -EINVAL;
			goto free_pbc;
		}


		idx++;
		while (pktnwc < pktnw && idx < niov) {
			const size_t slen = iov[idx].iov_len;
			const unsigned long faddr =
				(unsigned long) iov[idx].iov_base;

			if (slen & 3 || faddr & 3 || !slen ||
			    slen > PAGE_SIZE) {
				ret = -EINVAL;
				goto free_pbc;
			}

			npages++;
			if ((faddr & PAGE_MASK) !=
			    ((faddr + slen - 1) & PAGE_MASK))
				npages++;

			pktnwc += slen >> 2;
			idx++;
			nfrags++;
		}

		if (pktnwc != pktnw) {
			ret = -EINVAL;
			goto free_pbc;
		}

		if (page) {
			dma_addr = dma_map_page(&dd->pcidev->dev,
						page, 0, len, DMA_TO_DEVICE);
			if (dma_mapping_error(&dd->pcidev->dev, dma_addr)) {
				ret = -ENOMEM;
				goto free_pbc;
			}

			dma_mapped = 1;
		}

		ipath_user_sdma_init_header(pkt, counter, 0, len, dma_mapped,
					    page, pbc, dma_addr);

		if (nfrags) {
			ret = ipath_user_sdma_init_payload(dd, pq, pkt,
							   iov + idx_save + 1,
							   nfrags, npages);
			if (ret < 0)
				goto free_pbc_dma;
		}

		counter++;
		npkts++;

		list_add_tail(&pkt->list, list);
	}

	ret = idx;
	goto done;

free_pbc_dma:
	if (dma_mapped)
		dma_unmap_page(&dd->pcidev->dev, dma_addr, len, DMA_TO_DEVICE);
free_pbc:
	if (page) {
		kunmap(page);
		__free_page(page);
	} else
		dma_pool_free(pq->header_cache, pbc, dma_addr);
free_pkt:
	kmem_cache_free(pq->pkt_slab, pkt);
free_list:
	ipath_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, list);
done:
	return ret;
}

static void ipath_user_sdma_set_complete_counter(struct ipath_user_sdma_queue *pq,
						 u32 c)
{
	pq->sent_counter = c;
}

/* try to clean out queue -- needs pq->lock */
static int ipath_user_sdma_queue_clean(const struct ipath_devdata *dd,
				       struct ipath_user_sdma_queue *pq)
{
	struct list_head free_list;
	struct ipath_user_sdma_pkt *pkt;
	struct ipath_user_sdma_pkt *pkt_prev;
	int ret = 0;

	INIT_LIST_HEAD(&free_list);

	list_for_each_entry_safe(pkt, pkt_prev, &pq->sent, list) {
		s64 descd = dd->ipath_sdma_descq_removed - pkt->added;

		if (descd < 0)
			break;

		list_move_tail(&pkt->list, &free_list);

		/* one more packet cleaned */
		ret++;
	}

	if (!list_empty(&free_list)) {
		u32 counter;

		pkt = list_entry(free_list.prev,
				 struct ipath_user_sdma_pkt, list);
		counter = pkt->counter;

		ipath_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &free_list);
		ipath_user_sdma_set_complete_counter(pq, counter);
	}

	return ret;
}

void ipath_user_sdma_queue_destroy(struct ipath_user_sdma_queue *pq)
{
	if (!pq)
		return;

	kmem_cache_destroy(pq->pkt_slab);
	dma_pool_destroy(pq->header_cache);
	kfree(pq);
}

/* clean descriptor queue, returns > 0 if some elements cleaned */
static int ipath_user_sdma_hwqueue_clean(struct ipath_devdata *dd)
{
	int ret;
	unsigned long flags;

	spin_lock_irqsave(&dd->ipath_sdma_lock, flags);
	ret = ipath_sdma_make_progress(dd);
	spin_unlock_irqrestore(&dd->ipath_sdma_lock, flags);

	return ret;
}

/* we're in close, drain packets so that we can cleanup successfully... */
void ipath_user_sdma_queue_drain(struct ipath_devdata *dd,
				 struct ipath_user_sdma_queue *pq)
{
	int i;

	if (!pq)
		return;

	for (i = 0; i < 100; i++) {
		mutex_lock(&pq->lock);
		if (list_empty(&pq->sent)) {
			mutex_unlock(&pq->lock);
			break;
		}
		ipath_user_sdma_hwqueue_clean(dd);
		ipath_user_sdma_queue_clean(dd, pq);
		mutex_unlock(&pq->lock);
		msleep(10);
	}

	if (!list_empty(&pq->sent)) {
		struct list_head free_list;

		printk(KERN_INFO "drain: lists not empty: forcing!\n");
		INIT_LIST_HEAD(&free_list);
		mutex_lock(&pq->lock);
		list_splice_init(&pq->sent, &free_list);
		ipath_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &free_list);
		mutex_unlock(&pq->lock);
	}
}

static inline __le64 ipath_sdma_make_desc0(struct ipath_devdata *dd,
					   u64 addr, u64 dwlen, u64 dwoffset)
{
	return cpu_to_le64(/* SDmaPhyAddr[31:0] */
			   ((addr & 0xfffffffcULL) << 32) |
			   /* SDmaGeneration[1:0] */
			   ((dd->ipath_sdma_generation & 3ULL) << 30) |
			   /* SDmaDwordCount[10:0] */
			   ((dwlen & 0x7ffULL) << 16) |
			   /* SDmaBufOffset[12:2] */
			   (dwoffset & 0x7ffULL));
}

static inline __le64 ipath_sdma_make_first_desc0(__le64 descq)
{
	return descq | cpu_to_le64(1ULL << 12);
}

static inline __le64 ipath_sdma_make_last_desc0(__le64 descq)
{
					      /* last */  /* dma head */
	return descq | cpu_to_le64(1ULL << 11 | 1ULL << 13);
}

static inline __le64 ipath_sdma_make_desc1(u64 addr)
{
	/* SDmaPhyAddr[47:32] */
	return cpu_to_le64(addr >> 32);
}

static void ipath_user_sdma_send_frag(struct ipath_devdata *dd,
				      struct ipath_user_sdma_pkt *pkt, int idx,
				      unsigned ofs, u16 tail)
{
	const u64 addr = (u64) pkt->addr[idx].addr +
		(u64) pkt->addr[idx].offset;
	const u64 dwlen = (u64) pkt->addr[idx].length / 4;
	__le64 *descqp;
	__le64 descq0;

	descqp = &dd->ipath_sdma_descq[tail].qw[0];

	descq0 = ipath_sdma_make_desc0(dd, addr, dwlen, ofs);
	if (idx == 0)
		descq0 = ipath_sdma_make_first_desc0(descq0);
	if (idx == pkt->naddr - 1)
		descq0 = ipath_sdma_make_last_desc0(descq0);

	descqp[0] = descq0;
	descqp[1] = ipath_sdma_make_desc1(addr);
}

/* pq->lock must be held, get packets on the wire... */
static int ipath_user_sdma_push_pkts(struct ipath_devdata *dd,
				     struct ipath_user_sdma_queue *pq,
				     struct list_head *pktlist)
{
	int ret = 0;
	unsigned long flags;
	u16 tail;

	if (list_empty(pktlist))
		return 0;

	if (unlikely(!(dd->ipath_flags & IPATH_LINKACTIVE)))
		return -ECOMM;

	spin_lock_irqsave(&dd->ipath_sdma_lock, flags);

	if (unlikely(dd->ipath_sdma_status & IPATH_SDMA_ABORT_MASK)) {
		ret = -ECOMM;
		goto unlock;
	}

	tail = dd->ipath_sdma_descq_tail;
	while (!list_empty(pktlist)) {
		struct ipath_user_sdma_pkt *pkt =
			list_entry(pktlist->next, struct ipath_user_sdma_pkt,
				   list);
		int i;
		unsigned ofs = 0;
		u16 dtail = tail;

		if (pkt->naddr > ipath_sdma_descq_freecnt(dd))
			goto unlock_check_tail;

		for (i = 0; i < pkt->naddr; i++) {
			ipath_user_sdma_send_frag(dd, pkt, i, ofs, tail);
			ofs += pkt->addr[i].length >> 2;

			if (++tail == dd->ipath_sdma_descq_cnt) {
				tail = 0;
				++dd->ipath_sdma_generation;
			}
		}

		if ((ofs<<2) > dd->ipath_ibmaxlen) {
			ipath_dbg("packet size %X > ibmax %X, fail\n",
				ofs<<2, dd->ipath_ibmaxlen);
			ret = -EMSGSIZE;
			goto unlock;
		}

		/*
		 * if the packet is >= 2KB mtu equivalent, we have to use
		 * the large buffers, and have to mark each descriptor as
		 * part of a large buffer packet.
		 */
		if (ofs >= IPATH_SMALLBUF_DWORDS) {
			for (i = 0; i < pkt->naddr; i++) {
				dd->ipath_sdma_descq[dtail].qw[0] |=
					cpu_to_le64(1ULL << 14);
				if (++dtail == dd->ipath_sdma_descq_cnt)
					dtail = 0;
			}
		}

		dd->ipath_sdma_descq_added += pkt->naddr;
		pkt->added = dd->ipath_sdma_descq_added;
		list_move_tail(&pkt->list, &pq->sent);
		ret++;
	}

unlock_check_tail:
	/* advance the tail on the chip if necessary */
	if (dd->ipath_sdma_descq_tail != tail) {
		wmb();
		ipath_write_kreg(dd, dd->ipath_kregs->kr_senddmatail, tail);
		dd->ipath_sdma_descq_tail = tail;
	}

unlock:
	spin_unlock_irqrestore(&dd->ipath_sdma_lock, flags);

	return ret;
}

int ipath_user_sdma_writev(struct ipath_devdata *dd,
			   struct ipath_user_sdma_queue *pq,
			   const struct iovec *iov,
			   unsigned long dim)
{
	int ret = 0;
	struct list_head list;
	int npkts = 0;

	INIT_LIST_HEAD(&list);

	mutex_lock(&pq->lock);

	if (dd->ipath_sdma_descq_added != dd->ipath_sdma_descq_removed) {
		ipath_user_sdma_hwqueue_clean(dd);
		ipath_user_sdma_queue_clean(dd, pq);
	}

	while (dim) {
		const int mxp = 8;

		down_write(&current->mm->mmap_sem);
		ret = ipath_user_sdma_queue_pkts(dd, pq, &list, iov, dim, mxp);
		up_write(&current->mm->mmap_sem);

		if (ret <= 0)
			goto done_unlock;
		else {
			dim -= ret;
			iov += ret;
		}

		/* force packets onto the sdma hw queue... */
		if (!list_empty(&list)) {
			/*
			 * lazily clean hw queue.  the 4 is a guess of about
			 * how many sdma descriptors a packet will take (it
			 * doesn't have to be perfect).
			 */
			if (ipath_sdma_descq_freecnt(dd) < ret * 4) {
				ipath_user_sdma_hwqueue_clean(dd);
				ipath_user_sdma_queue_clean(dd, pq);
			}

			ret = ipath_user_sdma_push_pkts(dd, pq, &list);
			if (ret < 0)
				goto done_unlock;
			else {
				npkts += ret;
				pq->counter += ret;

				if (!list_empty(&list))
					goto done_unlock;
			}
		}
	}

done_unlock:
	if (!list_empty(&list))
		ipath_user_sdma_free_pkt_list(&dd->pcidev->dev, pq, &list);
	mutex_unlock(&pq->lock);

	return (ret < 0) ? ret : npkts;
}

int ipath_user_sdma_make_progress(struct ipath_devdata *dd,
				  struct ipath_user_sdma_queue *pq)
{
	int ret = 0;

	mutex_lock(&pq->lock);
	ipath_user_sdma_hwqueue_clean(dd);
	ret = ipath_user_sdma_queue_clean(dd, pq);
	mutex_unlock(&pq->lock);

	return ret;
}

u32 ipath_user_sdma_complete_counter(const struct ipath_user_sdma_queue *pq)
{
	return pq->sent_counter;
}

u32 ipath_user_sdma_inflight_counter(struct ipath_user_sdma_queue *pq)
{
	return pq->counter;
}