summaryrefslogtreecommitdiff
path: root/drivers/media/v4l2-core/videobuf-dma-sg.c
blob: 0b5c43f7e020da59c939369ebd9d0a27a116ce2b (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
/*
 * helper functions for SG DMA video4linux capture buffers
 *
 * The functions expect the hardware being able to scatter gather
 * (i.e. the buffers are not linear in physical memory, but fragmented
 * into PAGE_SIZE chunks).  They also assume the driver does not need
 * to touch the video data.
 *
 * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
 *
 * Highly based on video-buf written originally by:
 * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
 * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
 * (c) 2006 Ted Walther and John Sokol
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
#include <linux/interrupt.h>

#include <linux/dma-mapping.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/scatterlist.h>
#include <asm/page.h>
#include <asm/pgtable.h>

#include <media/videobuf-dma-sg.h>

#define MAGIC_DMABUF 0x19721112
#define MAGIC_SG_MEM 0x17890714

#define MAGIC_CHECK(is, should)						\
	if (unlikely((is) != (should))) {				\
		printk(KERN_ERR "magic mismatch: %x (expected %x)\n",	\
				is, should);				\
		BUG();							\
	}

static int debug;
module_param(debug, int, 0644);

MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
MODULE_LICENSE("GPL");

#define dprintk(level, fmt, arg...)					\
	if (debug >= level)						\
		printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)

/* --------------------------------------------------------------------- */

/*
 * Return a scatterlist for some page-aligned vmalloc()'ed memory
 * block (NULL on errors).  Memory for the scatterlist is allocated
 * using kmalloc.  The caller must free the memory.
 */
static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
						  int nr_pages)
{
	struct scatterlist *sglist;
	struct page *pg;
	int i;

	sglist = vzalloc(nr_pages * sizeof(*sglist));
	if (NULL == sglist)
		return NULL;
	sg_init_table(sglist, nr_pages);
	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
		pg = vmalloc_to_page(virt);
		if (NULL == pg)
			goto err;
		BUG_ON(PageHighMem(pg));
		sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
	}
	return sglist;

err:
	vfree(sglist);
	return NULL;
}

/*
 * Return a scatterlist for a an array of userpages (NULL on errors).
 * Memory for the scatterlist is allocated using kmalloc.  The caller
 * must free the memory.
 */
static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
					int nr_pages, int offset, size_t size)
{
	struct scatterlist *sglist;
	int i;

	if (NULL == pages[0])
		return NULL;
	sglist = vmalloc(nr_pages * sizeof(*sglist));
	if (NULL == sglist)
		return NULL;
	sg_init_table(sglist, nr_pages);

	if (PageHighMem(pages[0]))
		/* DMA to highmem pages might not work */
		goto highmem;
	sg_set_page(&sglist[0], pages[0],
			min_t(size_t, PAGE_SIZE - offset, size), offset);
	size -= min_t(size_t, PAGE_SIZE - offset, size);
	for (i = 1; i < nr_pages; i++) {
		if (NULL == pages[i])
			goto nopage;
		if (PageHighMem(pages[i]))
			goto highmem;
		sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
		size -= min_t(size_t, PAGE_SIZE, size);
	}
	return sglist;

nopage:
	dprintk(2, "sgl: oops - no page\n");
	vfree(sglist);
	return NULL;

highmem:
	dprintk(2, "sgl: oops - highmem page\n");
	vfree(sglist);
	return NULL;
}

/* --------------------------------------------------------------------- */

struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
{
	struct videobuf_dma_sg_memory *mem = buf->priv;
	BUG_ON(!mem);

	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

	return &mem->dma;
}
EXPORT_SYMBOL_GPL(videobuf_to_dma);

static void videobuf_dma_init(struct videobuf_dmabuf *dma)
{
	memset(dma, 0, sizeof(*dma));
	dma->magic = MAGIC_DMABUF;
}

static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
			int direction, unsigned long data, unsigned long size)
{
	unsigned long first, last;
	int err, rw = 0;
	unsigned int flags = FOLL_FORCE;

	dma->direction = direction;
	switch (dma->direction) {
	case DMA_FROM_DEVICE:
		rw = READ;
		break;
	case DMA_TO_DEVICE:
		rw = WRITE;
		break;
	default:
		BUG();
	}

	first = (data          & PAGE_MASK) >> PAGE_SHIFT;
	last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
	dma->offset = data & ~PAGE_MASK;
	dma->size = size;
	dma->nr_pages = last-first+1;
	dma->pages = kmalloc(dma->nr_pages * sizeof(struct page *), GFP_KERNEL);
	if (NULL == dma->pages)
		return -ENOMEM;

	if (rw == READ)
		flags |= FOLL_WRITE;

	dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
		data, size, dma->nr_pages);

	err = get_user_pages(data & PAGE_MASK, dma->nr_pages,
			     flags, dma->pages, NULL);

	if (err != dma->nr_pages) {
		dma->nr_pages = (err >= 0) ? err : 0;
		dprintk(1, "get_user_pages: err=%d [%d]\n", err, dma->nr_pages);
		return err < 0 ? err : -EINVAL;
	}
	return 0;
}

static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
			   unsigned long data, unsigned long size)
{
	int ret;

	down_read(&current->mm->mmap_sem);
	ret = videobuf_dma_init_user_locked(dma, direction, data, size);
	up_read(&current->mm->mmap_sem);

	return ret;
}

static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
			     int nr_pages)
{
	int i;

	dprintk(1, "init kernel [%d pages]\n", nr_pages);

	dma->direction = direction;
	dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
				   GFP_KERNEL);
	if (!dma->vaddr_pages)
		return -ENOMEM;

	dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
	if (!dma->dma_addr) {
		kfree(dma->vaddr_pages);
		return -ENOMEM;
	}
	for (i = 0; i < nr_pages; i++) {
		void *addr;

		addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
					  &(dma->dma_addr[i]), GFP_KERNEL);
		if (addr == NULL)
			goto out_free_pages;

		dma->vaddr_pages[i] = virt_to_page(addr);
	}
	dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
			  PAGE_KERNEL);
	if (NULL == dma->vaddr) {
		dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
		goto out_free_pages;
	}

	dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
				(unsigned long)dma->vaddr,
				nr_pages << PAGE_SHIFT);

	memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
	dma->nr_pages = nr_pages;

	return 0;
out_free_pages:
	while (i > 0) {
		void *addr;

		i--;
		addr = page_address(dma->vaddr_pages[i]);
		dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
	}
	kfree(dma->dma_addr);
	dma->dma_addr = NULL;
	kfree(dma->vaddr_pages);
	dma->vaddr_pages = NULL;

	return -ENOMEM;

}

static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
			      dma_addr_t addr, int nr_pages)
{
	dprintk(1, "init overlay [%d pages @ bus 0x%lx]\n",
		nr_pages, (unsigned long)addr);
	dma->direction = direction;

	if (0 == addr)
		return -EINVAL;

	dma->bus_addr = addr;
	dma->nr_pages = nr_pages;

	return 0;
}

static int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
{
	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
	BUG_ON(0 == dma->nr_pages);

	if (dma->pages) {
		dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
						   dma->offset, dma->size);
	}
	if (dma->vaddr) {
		dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
						     dma->nr_pages);
	}
	if (dma->bus_addr) {
		dma->sglist = vmalloc(sizeof(*dma->sglist));
		if (NULL != dma->sglist) {
			dma->sglen = 1;
			sg_dma_address(&dma->sglist[0])	= dma->bus_addr
							& PAGE_MASK;
			dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
			sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
		}
	}
	if (NULL == dma->sglist) {
		dprintk(1, "scatterlist is NULL\n");
		return -ENOMEM;
	}
	if (!dma->bus_addr) {
		dma->sglen = dma_map_sg(dev, dma->sglist,
					dma->nr_pages, dma->direction);
		if (0 == dma->sglen) {
			printk(KERN_WARNING
			       "%s: videobuf_map_sg failed\n", __func__);
			vfree(dma->sglist);
			dma->sglist = NULL;
			dma->sglen = 0;
			return -ENOMEM;
		}
	}

	return 0;
}

int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
{
	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);

	if (!dma->sglen)
		return 0;

	dma_unmap_sg(dev, dma->sglist, dma->sglen, dma->direction);

	vfree(dma->sglist);
	dma->sglist = NULL;
	dma->sglen = 0;

	return 0;
}
EXPORT_SYMBOL_GPL(videobuf_dma_unmap);

int videobuf_dma_free(struct videobuf_dmabuf *dma)
{
	int i;
	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
	BUG_ON(dma->sglen);

	if (dma->pages) {
		for (i = 0; i < dma->nr_pages; i++)
			put_page(dma->pages[i]);
		kfree(dma->pages);
		dma->pages = NULL;
	}

	if (dma->dma_addr) {
		for (i = 0; i < dma->nr_pages; i++) {
			void *addr;

			addr = page_address(dma->vaddr_pages[i]);
			dma_free_coherent(dma->dev, PAGE_SIZE, addr,
					  dma->dma_addr[i]);
		}
		kfree(dma->dma_addr);
		dma->dma_addr = NULL;
		kfree(dma->vaddr_pages);
		dma->vaddr_pages = NULL;
		vunmap(dma->vaddr);
		dma->vaddr = NULL;
	}

	if (dma->bus_addr)
		dma->bus_addr = 0;
	dma->direction = DMA_NONE;

	return 0;
}
EXPORT_SYMBOL_GPL(videobuf_dma_free);

/* --------------------------------------------------------------------- */

static void videobuf_vm_open(struct vm_area_struct *vma)
{
	struct videobuf_mapping *map = vma->vm_private_data;

	dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
		map->count, vma->vm_start, vma->vm_end);

	map->count++;
}

static void videobuf_vm_close(struct vm_area_struct *vma)
{
	struct videobuf_mapping *map = vma->vm_private_data;
	struct videobuf_queue *q = map->q;
	struct videobuf_dma_sg_memory *mem;
	int i;

	dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
		map->count, vma->vm_start, vma->vm_end);

	map->count--;
	if (0 == map->count) {
		dprintk(1, "munmap %p q=%p\n", map, q);
		videobuf_queue_lock(q);
		for (i = 0; i < VIDEO_MAX_FRAME; i++) {
			if (NULL == q->bufs[i])
				continue;
			mem = q->bufs[i]->priv;
			if (!mem)
				continue;

			MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

			if (q->bufs[i]->map != map)
				continue;
			q->bufs[i]->map   = NULL;
			q->bufs[i]->baddr = 0;
			q->ops->buf_release(q, q->bufs[i]);
		}
		videobuf_queue_unlock(q);
		kfree(map);
	}
	return;
}

/*
 * Get a anonymous page for the mapping.  Make sure we can DMA to that
 * memory location with 32bit PCI devices (i.e. don't use highmem for
 * now ...).  Bounce buffers don't work very well for the data rates
 * video capture has.
 */
static int videobuf_vm_fault(struct vm_fault *vmf)
{
	struct vm_area_struct *vma = vmf->vma;
	struct page *page;

	dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
		vmf->address, vma->vm_start, vma->vm_end);

	page = alloc_page(GFP_USER | __GFP_DMA32);
	if (!page)
		return VM_FAULT_OOM;
	clear_user_highpage(page, vmf->address);
	vmf->page = page;

	return 0;
}

static const struct vm_operations_struct videobuf_vm_ops = {
	.open	= videobuf_vm_open,
	.close	= videobuf_vm_close,
	.fault	= videobuf_vm_fault,
};

/* ---------------------------------------------------------------------
 * SG handlers for the generic methods
 */

/* Allocated area consists on 3 parts:
	struct video_buffer
	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
	struct videobuf_dma_sg_memory
 */

static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
{
	struct videobuf_dma_sg_memory *mem;
	struct videobuf_buffer *vb;

	vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
	if (!vb)
		return vb;

	mem = vb->priv = ((char *)vb) + size;
	mem->magic = MAGIC_SG_MEM;

	videobuf_dma_init(&mem->dma);

	dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
		__func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
		mem, (long)sizeof(*mem));

	return vb;
}

static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
{
	struct videobuf_dma_sg_memory *mem = buf->priv;
	BUG_ON(!mem);

	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

	return mem->dma.vaddr;
}

static int __videobuf_iolock(struct videobuf_queue *q,
			     struct videobuf_buffer *vb,
			     struct v4l2_framebuffer *fbuf)
{
	int err, pages;
	dma_addr_t bus;
	struct videobuf_dma_sg_memory *mem = vb->priv;
	BUG_ON(!mem);

	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

	if (!mem->dma.dev)
		mem->dma.dev = q->dev;
	else
		WARN_ON(mem->dma.dev != q->dev);

	switch (vb->memory) {
	case V4L2_MEMORY_MMAP:
	case V4L2_MEMORY_USERPTR:
		if (0 == vb->baddr) {
			/* no userspace addr -- kernel bounce buffer */
			pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
			err = videobuf_dma_init_kernel(&mem->dma,
						       DMA_FROM_DEVICE,
						       pages);
			if (0 != err)
				return err;
		} else if (vb->memory == V4L2_MEMORY_USERPTR) {
			/* dma directly to userspace */
			err = videobuf_dma_init_user(&mem->dma,
						     DMA_FROM_DEVICE,
						     vb->baddr, vb->bsize);
			if (0 != err)
				return err;
		} else {
			/* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
			buffers can only be called from videobuf_qbuf
			we take current->mm->mmap_sem there, to prevent
			locking inversion, so don't take it here */

			err = videobuf_dma_init_user_locked(&mem->dma,
						      DMA_FROM_DEVICE,
						      vb->baddr, vb->bsize);
			if (0 != err)
				return err;
		}
		break;
	case V4L2_MEMORY_OVERLAY:
		if (NULL == fbuf)
			return -EINVAL;
		/* FIXME: need sanity checks for vb->boff */
		/*
		 * Using a double cast to avoid compiler warnings when
		 * building for PAE. Compiler doesn't like direct casting
		 * of a 32 bit ptr to 64 bit integer.
		 */
		bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
		pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
		err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
						bus, pages);
		if (0 != err)
			return err;
		break;
	default:
		BUG();
	}
	err = videobuf_dma_map(q->dev, &mem->dma);
	if (0 != err)
		return err;

	return 0;
}

static int __videobuf_sync(struct videobuf_queue *q,
			   struct videobuf_buffer *buf)
{
	struct videobuf_dma_sg_memory *mem = buf->priv;
	BUG_ON(!mem || !mem->dma.sglen);

	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
	MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);

	dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
			    mem->dma.sglen, mem->dma.direction);

	return 0;
}

static int __videobuf_mmap_mapper(struct videobuf_queue *q,
				  struct videobuf_buffer *buf,
				  struct vm_area_struct *vma)
{
	struct videobuf_dma_sg_memory *mem = buf->priv;
	struct videobuf_mapping *map;
	unsigned int first, last, size = 0, i;
	int retval;

	retval = -EINVAL;

	BUG_ON(!mem);
	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);

	/* look for first buffer to map */
	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
		if (buf == q->bufs[first]) {
			size = PAGE_ALIGN(q->bufs[first]->bsize);
			break;
		}
	}

	/* paranoia, should never happen since buf is always valid. */
	if (!size) {
		dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
				(vma->vm_pgoff << PAGE_SHIFT));
		goto done;
	}

	last = first;

	/* create mapping + update buffer list */
	retval = -ENOMEM;
	map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
	if (NULL == map)
		goto done;

	size = 0;
	for (i = first; i <= last; i++) {
		if (NULL == q->bufs[i])
			continue;
		q->bufs[i]->map   = map;
		q->bufs[i]->baddr = vma->vm_start + size;
		size += PAGE_ALIGN(q->bufs[i]->bsize);
	}

	map->count    = 1;
	map->q        = q;
	vma->vm_ops   = &videobuf_vm_ops;
	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
	vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
	vma->vm_private_data = map;
	dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
		map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
	retval = 0;

done:
	return retval;
}

static struct videobuf_qtype_ops sg_ops = {
	.magic        = MAGIC_QTYPE_OPS,

	.alloc_vb     = __videobuf_alloc_vb,
	.iolock       = __videobuf_iolock,
	.sync         = __videobuf_sync,
	.mmap_mapper  = __videobuf_mmap_mapper,
	.vaddr        = __videobuf_to_vaddr,
};

void *videobuf_sg_alloc(size_t size)
{
	struct videobuf_queue q;

	/* Required to make generic handler to call __videobuf_alloc */
	q.int_ops = &sg_ops;

	q.msize = size;

	return videobuf_alloc_vb(&q);
}
EXPORT_SYMBOL_GPL(videobuf_sg_alloc);

void videobuf_queue_sg_init(struct videobuf_queue *q,
			 const struct videobuf_queue_ops *ops,
			 struct device *dev,
			 spinlock_t *irqlock,
			 enum v4l2_buf_type type,
			 enum v4l2_field field,
			 unsigned int msize,
			 void *priv,
			 struct mutex *ext_lock)
{
	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
				 priv, &sg_ops, ext_lock);
}
EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);