1 /*
2  * helper functions for SG DMA video4linux capture buffers
3  *
4  * The functions expect the hardware being able to scatter gather
5  * (i.e. the buffers are not linear in physical memory, but fragmented
6  * into PAGE_SIZE chunks).  They also assume the driver does not need
7  * to touch the video data.
8  *
9  * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
10  *
11  * Highly based on video-buf written originally by:
12  * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
13  * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
14  * (c) 2006 Ted Walther and John Sokol
15  *
16  * This program is free software; you can redistribute it and/or modify
17  * it under the terms of the GNU General Public License as published by
18  * the Free Software Foundation; either version 2
19  */
20 
21 #include <linux/init.h>
22 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/sched.h>
25 #include <linux/slab.h>
26 #include <linux/interrupt.h>
27 
28 #include <linux/dma-mapping.h>
29 #include <linux/vmalloc.h>
30 #include <linux/pagemap.h>
31 #include <linux/scatterlist.h>
32 #include <asm/page.h>
33 #include <asm/pgtable.h>
34 
35 #include <media/videobuf-dma-sg.h>
36 
37 #define MAGIC_DMABUF 0x19721112
38 #define MAGIC_SG_MEM 0x17890714
39 
40 #define MAGIC_CHECK(is, should)						\
41 	if (unlikely((is) != (should))) {				\
42 		printk(KERN_ERR "magic mismatch: %x (expected %x)\n",	\
43 				is, should);				\
44 		BUG();							\
45 	}
46 
47 static int debug;
48 module_param(debug, int, 0644);
49 
50 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
51 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
52 MODULE_LICENSE("GPL");
53 
54 #define dprintk(level, fmt, arg...)					\
55 	if (debug >= level)						\
56 		printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
57 
58 /* --------------------------------------------------------------------- */
59 
60 /*
61  * Return a scatterlist for some page-aligned vmalloc()'ed memory
62  * block (NULL on errors).  Memory for the scatterlist is allocated
63  * using kmalloc.  The caller must free the memory.
64  */
65 static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
66 						  int nr_pages)
67 {
68 	struct scatterlist *sglist;
69 	struct page *pg;
70 	int i;
71 
72 	sglist = vzalloc(nr_pages * sizeof(*sglist));
73 	if (NULL == sglist)
74 		return NULL;
75 	sg_init_table(sglist, nr_pages);
76 	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
77 		pg = vmalloc_to_page(virt);
78 		if (NULL == pg)
79 			goto err;
80 		BUG_ON(PageHighMem(pg));
81 		sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
82 	}
83 	return sglist;
84 
85 err:
86 	vfree(sglist);
87 	return NULL;
88 }
89 
90 /*
91  * Return a scatterlist for a an array of userpages (NULL on errors).
92  * Memory for the scatterlist is allocated using kmalloc.  The caller
93  * must free the memory.
94  */
95 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
96 					int nr_pages, int offset, size_t size)
97 {
98 	struct scatterlist *sglist;
99 	int i;
100 
101 	if (NULL == pages[0])
102 		return NULL;
103 	sglist = vmalloc(nr_pages * sizeof(*sglist));
104 	if (NULL == sglist)
105 		return NULL;
106 	sg_init_table(sglist, nr_pages);
107 
108 	if (PageHighMem(pages[0]))
109 		/* DMA to highmem pages might not work */
110 		goto highmem;
111 	sg_set_page(&sglist[0], pages[0],
112 			min_t(size_t, PAGE_SIZE - offset, size), offset);
113 	size -= min_t(size_t, PAGE_SIZE - offset, size);
114 	for (i = 1; i < nr_pages; i++) {
115 		if (NULL == pages[i])
116 			goto nopage;
117 		if (PageHighMem(pages[i]))
118 			goto highmem;
119 		sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
120 		size -= min_t(size_t, PAGE_SIZE, size);
121 	}
122 	return sglist;
123 
124 nopage:
125 	dprintk(2, "sgl: oops - no page\n");
126 	vfree(sglist);
127 	return NULL;
128 
129 highmem:
130 	dprintk(2, "sgl: oops - highmem page\n");
131 	vfree(sglist);
132 	return NULL;
133 }
134 
135 /* --------------------------------------------------------------------- */
136 
137 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
138 {
139 	struct videobuf_dma_sg_memory *mem = buf->priv;
140 	BUG_ON(!mem);
141 
142 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
143 
144 	return &mem->dma;
145 }
146 EXPORT_SYMBOL_GPL(videobuf_to_dma);
147 
148 static void videobuf_dma_init(struct videobuf_dmabuf *dma)
149 {
150 	memset(dma, 0, sizeof(*dma));
151 	dma->magic = MAGIC_DMABUF;
152 }
153 
154 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
155 			int direction, unsigned long data, unsigned long size)
156 {
157 	unsigned long first, last;
158 	int err, rw = 0;
159 
160 	dma->direction = direction;
161 	switch (dma->direction) {
162 	case DMA_FROM_DEVICE:
163 		rw = READ;
164 		break;
165 	case DMA_TO_DEVICE:
166 		rw = WRITE;
167 		break;
168 	default:
169 		BUG();
170 	}
171 
172 	first = (data          & PAGE_MASK) >> PAGE_SHIFT;
173 	last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
174 	dma->offset = data & ~PAGE_MASK;
175 	dma->size = size;
176 	dma->nr_pages = last-first+1;
177 	dma->pages = kmalloc(dma->nr_pages * sizeof(struct page *), GFP_KERNEL);
178 	if (NULL == dma->pages)
179 		return -ENOMEM;
180 
181 	dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
182 		data, size, dma->nr_pages);
183 
184 	err = get_user_pages(current, current->mm,
185 			     data & PAGE_MASK, dma->nr_pages,
186 			     rw == READ, 1, /* force */
187 			     dma->pages, NULL);
188 
189 	if (err != dma->nr_pages) {
190 		dma->nr_pages = (err >= 0) ? err : 0;
191 		dprintk(1, "get_user_pages: err=%d [%d]\n", err, dma->nr_pages);
192 		return err < 0 ? err : -EINVAL;
193 	}
194 	return 0;
195 }
196 
197 static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
198 			   unsigned long data, unsigned long size)
199 {
200 	int ret;
201 
202 	down_read(&current->mm->mmap_sem);
203 	ret = videobuf_dma_init_user_locked(dma, direction, data, size);
204 	up_read(&current->mm->mmap_sem);
205 
206 	return ret;
207 }
208 
209 static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
210 			     int nr_pages)
211 {
212 	int i;
213 
214 	dprintk(1, "init kernel [%d pages]\n", nr_pages);
215 
216 	dma->direction = direction;
217 	dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
218 				   GFP_KERNEL);
219 	if (!dma->vaddr_pages)
220 		return -ENOMEM;
221 
222 	dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
223 	if (!dma->dma_addr) {
224 		kfree(dma->vaddr_pages);
225 		return -ENOMEM;
226 	}
227 	for (i = 0; i < nr_pages; i++) {
228 		void *addr;
229 
230 		addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
231 					  &(dma->dma_addr[i]), GFP_KERNEL);
232 		if (addr == NULL)
233 			goto out_free_pages;
234 
235 		dma->vaddr_pages[i] = virt_to_page(addr);
236 	}
237 	dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
238 			  PAGE_KERNEL);
239 	if (NULL == dma->vaddr) {
240 		dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
241 		goto out_free_pages;
242 	}
243 
244 	dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
245 				(unsigned long)dma->vaddr,
246 				nr_pages << PAGE_SHIFT);
247 
248 	memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
249 	dma->nr_pages = nr_pages;
250 
251 	return 0;
252 out_free_pages:
253 	while (i > 0) {
254 		void *addr;
255 
256 		i--;
257 		addr = page_address(dma->vaddr_pages[i]);
258 		dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
259 	}
260 	kfree(dma->dma_addr);
261 	dma->dma_addr = NULL;
262 	kfree(dma->vaddr_pages);
263 	dma->vaddr_pages = NULL;
264 
265 	return -ENOMEM;
266 
267 }
268 
269 static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
270 			      dma_addr_t addr, int nr_pages)
271 {
272 	dprintk(1, "init overlay [%d pages @ bus 0x%lx]\n",
273 		nr_pages, (unsigned long)addr);
274 	dma->direction = direction;
275 
276 	if (0 == addr)
277 		return -EINVAL;
278 
279 	dma->bus_addr = addr;
280 	dma->nr_pages = nr_pages;
281 
282 	return 0;
283 }
284 
285 static int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
286 {
287 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
288 	BUG_ON(0 == dma->nr_pages);
289 
290 	if (dma->pages) {
291 		dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
292 						   dma->offset, dma->size);
293 	}
294 	if (dma->vaddr) {
295 		dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
296 						     dma->nr_pages);
297 	}
298 	if (dma->bus_addr) {
299 		dma->sglist = vmalloc(sizeof(*dma->sglist));
300 		if (NULL != dma->sglist) {
301 			dma->sglen = 1;
302 			sg_dma_address(&dma->sglist[0])	= dma->bus_addr
303 							& PAGE_MASK;
304 			dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
305 			sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
306 		}
307 	}
308 	if (NULL == dma->sglist) {
309 		dprintk(1, "scatterlist is NULL\n");
310 		return -ENOMEM;
311 	}
312 	if (!dma->bus_addr) {
313 		dma->sglen = dma_map_sg(dev, dma->sglist,
314 					dma->nr_pages, dma->direction);
315 		if (0 == dma->sglen) {
316 			printk(KERN_WARNING
317 			       "%s: videobuf_map_sg failed\n", __func__);
318 			vfree(dma->sglist);
319 			dma->sglist = NULL;
320 			dma->sglen = 0;
321 			return -ENOMEM;
322 		}
323 	}
324 
325 	return 0;
326 }
327 
328 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
329 {
330 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
331 
332 	if (!dma->sglen)
333 		return 0;
334 
335 	dma_unmap_sg(dev, dma->sglist, dma->sglen, dma->direction);
336 
337 	vfree(dma->sglist);
338 	dma->sglist = NULL;
339 	dma->sglen = 0;
340 
341 	return 0;
342 }
343 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
344 
345 int videobuf_dma_free(struct videobuf_dmabuf *dma)
346 {
347 	int i;
348 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
349 	BUG_ON(dma->sglen);
350 
351 	if (dma->pages) {
352 		for (i = 0; i < dma->nr_pages; i++)
353 			page_cache_release(dma->pages[i]);
354 		kfree(dma->pages);
355 		dma->pages = NULL;
356 	}
357 
358 	if (dma->dma_addr) {
359 		for (i = 0; i < dma->nr_pages; i++) {
360 			void *addr;
361 
362 			addr = page_address(dma->vaddr_pages[i]);
363 			dma_free_coherent(dma->dev, PAGE_SIZE, addr,
364 					  dma->dma_addr[i]);
365 		}
366 		kfree(dma->dma_addr);
367 		dma->dma_addr = NULL;
368 		kfree(dma->vaddr_pages);
369 		dma->vaddr_pages = NULL;
370 		vunmap(dma->vaddr);
371 		dma->vaddr = NULL;
372 	}
373 
374 	if (dma->bus_addr)
375 		dma->bus_addr = 0;
376 	dma->direction = DMA_NONE;
377 
378 	return 0;
379 }
380 EXPORT_SYMBOL_GPL(videobuf_dma_free);
381 
382 /* --------------------------------------------------------------------- */
383 
384 static void videobuf_vm_open(struct vm_area_struct *vma)
385 {
386 	struct videobuf_mapping *map = vma->vm_private_data;
387 
388 	dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
389 		map->count, vma->vm_start, vma->vm_end);
390 
391 	map->count++;
392 }
393 
394 static void videobuf_vm_close(struct vm_area_struct *vma)
395 {
396 	struct videobuf_mapping *map = vma->vm_private_data;
397 	struct videobuf_queue *q = map->q;
398 	struct videobuf_dma_sg_memory *mem;
399 	int i;
400 
401 	dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
402 		map->count, vma->vm_start, vma->vm_end);
403 
404 	map->count--;
405 	if (0 == map->count) {
406 		dprintk(1, "munmap %p q=%p\n", map, q);
407 		videobuf_queue_lock(q);
408 		for (i = 0; i < VIDEO_MAX_FRAME; i++) {
409 			if (NULL == q->bufs[i])
410 				continue;
411 			mem = q->bufs[i]->priv;
412 			if (!mem)
413 				continue;
414 
415 			MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
416 
417 			if (q->bufs[i]->map != map)
418 				continue;
419 			q->bufs[i]->map   = NULL;
420 			q->bufs[i]->baddr = 0;
421 			q->ops->buf_release(q, q->bufs[i]);
422 		}
423 		videobuf_queue_unlock(q);
424 		kfree(map);
425 	}
426 	return;
427 }
428 
429 /*
430  * Get a anonymous page for the mapping.  Make sure we can DMA to that
431  * memory location with 32bit PCI devices (i.e. don't use highmem for
432  * now ...).  Bounce buffers don't work very well for the data rates
433  * video capture has.
434  */
435 static int videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
436 {
437 	struct page *page;
438 
439 	dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
440 		(unsigned long)vmf->virtual_address,
441 		vma->vm_start, vma->vm_end);
442 
443 	page = alloc_page(GFP_USER | __GFP_DMA32);
444 	if (!page)
445 		return VM_FAULT_OOM;
446 	clear_user_highpage(page, (unsigned long)vmf->virtual_address);
447 	vmf->page = page;
448 
449 	return 0;
450 }
451 
452 static const struct vm_operations_struct videobuf_vm_ops = {
453 	.open	= videobuf_vm_open,
454 	.close	= videobuf_vm_close,
455 	.fault	= videobuf_vm_fault,
456 };
457 
458 /* ---------------------------------------------------------------------
459  * SG handlers for the generic methods
460  */
461 
462 /* Allocated area consists on 3 parts:
463 	struct video_buffer
464 	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
465 	struct videobuf_dma_sg_memory
466  */
467 
468 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
469 {
470 	struct videobuf_dma_sg_memory *mem;
471 	struct videobuf_buffer *vb;
472 
473 	vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
474 	if (!vb)
475 		return vb;
476 
477 	mem = vb->priv = ((char *)vb) + size;
478 	mem->magic = MAGIC_SG_MEM;
479 
480 	videobuf_dma_init(&mem->dma);
481 
482 	dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
483 		__func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
484 		mem, (long)sizeof(*mem));
485 
486 	return vb;
487 }
488 
489 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
490 {
491 	struct videobuf_dma_sg_memory *mem = buf->priv;
492 	BUG_ON(!mem);
493 
494 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
495 
496 	return mem->dma.vaddr;
497 }
498 
499 static int __videobuf_iolock(struct videobuf_queue *q,
500 			     struct videobuf_buffer *vb,
501 			     struct v4l2_framebuffer *fbuf)
502 {
503 	int err, pages;
504 	dma_addr_t bus;
505 	struct videobuf_dma_sg_memory *mem = vb->priv;
506 	BUG_ON(!mem);
507 
508 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
509 
510 	if (!mem->dma.dev)
511 		mem->dma.dev = q->dev;
512 	else
513 		WARN_ON(mem->dma.dev != q->dev);
514 
515 	switch (vb->memory) {
516 	case V4L2_MEMORY_MMAP:
517 	case V4L2_MEMORY_USERPTR:
518 		if (0 == vb->baddr) {
519 			/* no userspace addr -- kernel bounce buffer */
520 			pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
521 			err = videobuf_dma_init_kernel(&mem->dma,
522 						       DMA_FROM_DEVICE,
523 						       pages);
524 			if (0 != err)
525 				return err;
526 		} else if (vb->memory == V4L2_MEMORY_USERPTR) {
527 			/* dma directly to userspace */
528 			err = videobuf_dma_init_user(&mem->dma,
529 						     DMA_FROM_DEVICE,
530 						     vb->baddr, vb->bsize);
531 			if (0 != err)
532 				return err;
533 		} else {
534 			/* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
535 			buffers can only be called from videobuf_qbuf
536 			we take current->mm->mmap_sem there, to prevent
537 			locking inversion, so don't take it here */
538 
539 			err = videobuf_dma_init_user_locked(&mem->dma,
540 						      DMA_FROM_DEVICE,
541 						      vb->baddr, vb->bsize);
542 			if (0 != err)
543 				return err;
544 		}
545 		break;
546 	case V4L2_MEMORY_OVERLAY:
547 		if (NULL == fbuf)
548 			return -EINVAL;
549 		/* FIXME: need sanity checks for vb->boff */
550 		/*
551 		 * Using a double cast to avoid compiler warnings when
552 		 * building for PAE. Compiler doesn't like direct casting
553 		 * of a 32 bit ptr to 64 bit integer.
554 		 */
555 		bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
556 		pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
557 		err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
558 						bus, pages);
559 		if (0 != err)
560 			return err;
561 		break;
562 	default:
563 		BUG();
564 	}
565 	err = videobuf_dma_map(q->dev, &mem->dma);
566 	if (0 != err)
567 		return err;
568 
569 	return 0;
570 }
571 
572 static int __videobuf_sync(struct videobuf_queue *q,
573 			   struct videobuf_buffer *buf)
574 {
575 	struct videobuf_dma_sg_memory *mem = buf->priv;
576 	BUG_ON(!mem || !mem->dma.sglen);
577 
578 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
579 	MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
580 
581 	dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
582 			    mem->dma.sglen, mem->dma.direction);
583 
584 	return 0;
585 }
586 
587 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
588 				  struct videobuf_buffer *buf,
589 				  struct vm_area_struct *vma)
590 {
591 	struct videobuf_dma_sg_memory *mem = buf->priv;
592 	struct videobuf_mapping *map;
593 	unsigned int first, last, size = 0, i;
594 	int retval;
595 
596 	retval = -EINVAL;
597 
598 	BUG_ON(!mem);
599 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
600 
601 	/* look for first buffer to map */
602 	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
603 		if (buf == q->bufs[first]) {
604 			size = PAGE_ALIGN(q->bufs[first]->bsize);
605 			break;
606 		}
607 	}
608 
609 	/* paranoia, should never happen since buf is always valid. */
610 	if (!size) {
611 		dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
612 				(vma->vm_pgoff << PAGE_SHIFT));
613 		goto done;
614 	}
615 
616 	last = first;
617 
618 	/* create mapping + update buffer list */
619 	retval = -ENOMEM;
620 	map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
621 	if (NULL == map)
622 		goto done;
623 
624 	size = 0;
625 	for (i = first; i <= last; i++) {
626 		if (NULL == q->bufs[i])
627 			continue;
628 		q->bufs[i]->map   = map;
629 		q->bufs[i]->baddr = vma->vm_start + size;
630 		size += PAGE_ALIGN(q->bufs[i]->bsize);
631 	}
632 
633 	map->count    = 1;
634 	map->q        = q;
635 	vma->vm_ops   = &videobuf_vm_ops;
636 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
637 	vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
638 	vma->vm_private_data = map;
639 	dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
640 		map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
641 	retval = 0;
642 
643 done:
644 	return retval;
645 }
646 
647 static struct videobuf_qtype_ops sg_ops = {
648 	.magic        = MAGIC_QTYPE_OPS,
649 
650 	.alloc_vb     = __videobuf_alloc_vb,
651 	.iolock       = __videobuf_iolock,
652 	.sync         = __videobuf_sync,
653 	.mmap_mapper  = __videobuf_mmap_mapper,
654 	.vaddr        = __videobuf_to_vaddr,
655 };
656 
657 void *videobuf_sg_alloc(size_t size)
658 {
659 	struct videobuf_queue q;
660 
661 	/* Required to make generic handler to call __videobuf_alloc */
662 	q.int_ops = &sg_ops;
663 
664 	q.msize = size;
665 
666 	return videobuf_alloc_vb(&q);
667 }
668 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
669 
670 void videobuf_queue_sg_init(struct videobuf_queue *q,
671 			 const struct videobuf_queue_ops *ops,
672 			 struct device *dev,
673 			 spinlock_t *irqlock,
674 			 enum v4l2_buf_type type,
675 			 enum v4l2_field field,
676 			 unsigned int msize,
677 			 void *priv,
678 			 struct mutex *ext_lock)
679 {
680 	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
681 				 priv, &sg_ops, ext_lock);
682 }
683 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
684 
685