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/mm.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 	unsigned int flags = FOLL_FORCE;
160 
161 	dma->direction = direction;
162 	switch (dma->direction) {
163 	case DMA_FROM_DEVICE:
164 		rw = READ;
165 		break;
166 	case DMA_TO_DEVICE:
167 		rw = WRITE;
168 		break;
169 	default:
170 		BUG();
171 	}
172 
173 	first = (data          & PAGE_MASK) >> PAGE_SHIFT;
174 	last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
175 	dma->offset = data & ~PAGE_MASK;
176 	dma->size = size;
177 	dma->nr_pages = last-first+1;
178 	dma->pages = kmalloc(dma->nr_pages * sizeof(struct page *), GFP_KERNEL);
179 	if (NULL == dma->pages)
180 		return -ENOMEM;
181 
182 	if (rw == READ)
183 		flags |= FOLL_WRITE;
184 
185 	dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
186 		data, size, dma->nr_pages);
187 
188 	err = get_user_pages_longterm(data & PAGE_MASK, dma->nr_pages,
189 			     flags, dma->pages, NULL);
190 
191 	if (err != dma->nr_pages) {
192 		dma->nr_pages = (err >= 0) ? err : 0;
193 		dprintk(1, "get_user_pages_longterm: err=%d [%d]\n", err,
194 			dma->nr_pages);
195 		return err < 0 ? err : -EINVAL;
196 	}
197 	return 0;
198 }
199 
200 static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
201 			   unsigned long data, unsigned long size)
202 {
203 	int ret;
204 
205 	down_read(&current->mm->mmap_sem);
206 	ret = videobuf_dma_init_user_locked(dma, direction, data, size);
207 	up_read(&current->mm->mmap_sem);
208 
209 	return ret;
210 }
211 
212 static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
213 			     int nr_pages)
214 {
215 	int i;
216 
217 	dprintk(1, "init kernel [%d pages]\n", nr_pages);
218 
219 	dma->direction = direction;
220 	dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
221 				   GFP_KERNEL);
222 	if (!dma->vaddr_pages)
223 		return -ENOMEM;
224 
225 	dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
226 	if (!dma->dma_addr) {
227 		kfree(dma->vaddr_pages);
228 		return -ENOMEM;
229 	}
230 	for (i = 0; i < nr_pages; i++) {
231 		void *addr;
232 
233 		addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
234 					  &(dma->dma_addr[i]), GFP_KERNEL);
235 		if (addr == NULL)
236 			goto out_free_pages;
237 
238 		dma->vaddr_pages[i] = virt_to_page(addr);
239 	}
240 	dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
241 			  PAGE_KERNEL);
242 	if (NULL == dma->vaddr) {
243 		dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
244 		goto out_free_pages;
245 	}
246 
247 	dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
248 				(unsigned long)dma->vaddr,
249 				nr_pages << PAGE_SHIFT);
250 
251 	memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
252 	dma->nr_pages = nr_pages;
253 
254 	return 0;
255 out_free_pages:
256 	while (i > 0) {
257 		void *addr;
258 
259 		i--;
260 		addr = page_address(dma->vaddr_pages[i]);
261 		dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
262 	}
263 	kfree(dma->dma_addr);
264 	dma->dma_addr = NULL;
265 	kfree(dma->vaddr_pages);
266 	dma->vaddr_pages = NULL;
267 
268 	return -ENOMEM;
269 
270 }
271 
272 static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
273 			      dma_addr_t addr, int nr_pages)
274 {
275 	dprintk(1, "init overlay [%d pages @ bus 0x%lx]\n",
276 		nr_pages, (unsigned long)addr);
277 	dma->direction = direction;
278 
279 	if (0 == addr)
280 		return -EINVAL;
281 
282 	dma->bus_addr = addr;
283 	dma->nr_pages = nr_pages;
284 
285 	return 0;
286 }
287 
288 static int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
289 {
290 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
291 	BUG_ON(0 == dma->nr_pages);
292 
293 	if (dma->pages) {
294 		dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
295 						   dma->offset, dma->size);
296 	}
297 	if (dma->vaddr) {
298 		dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
299 						     dma->nr_pages);
300 	}
301 	if (dma->bus_addr) {
302 		dma->sglist = vmalloc(sizeof(*dma->sglist));
303 		if (NULL != dma->sglist) {
304 			dma->sglen = 1;
305 			sg_dma_address(&dma->sglist[0])	= dma->bus_addr
306 							& PAGE_MASK;
307 			dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
308 			sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
309 		}
310 	}
311 	if (NULL == dma->sglist) {
312 		dprintk(1, "scatterlist is NULL\n");
313 		return -ENOMEM;
314 	}
315 	if (!dma->bus_addr) {
316 		dma->sglen = dma_map_sg(dev, dma->sglist,
317 					dma->nr_pages, dma->direction);
318 		if (0 == dma->sglen) {
319 			printk(KERN_WARNING
320 			       "%s: videobuf_map_sg failed\n", __func__);
321 			vfree(dma->sglist);
322 			dma->sglist = NULL;
323 			dma->sglen = 0;
324 			return -ENOMEM;
325 		}
326 	}
327 
328 	return 0;
329 }
330 
331 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
332 {
333 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
334 
335 	if (!dma->sglen)
336 		return 0;
337 
338 	dma_unmap_sg(dev, dma->sglist, dma->sglen, dma->direction);
339 
340 	vfree(dma->sglist);
341 	dma->sglist = NULL;
342 	dma->sglen = 0;
343 
344 	return 0;
345 }
346 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
347 
348 int videobuf_dma_free(struct videobuf_dmabuf *dma)
349 {
350 	int i;
351 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
352 	BUG_ON(dma->sglen);
353 
354 	if (dma->pages) {
355 		for (i = 0; i < dma->nr_pages; i++)
356 			put_page(dma->pages[i]);
357 		kfree(dma->pages);
358 		dma->pages = NULL;
359 	}
360 
361 	if (dma->dma_addr) {
362 		for (i = 0; i < dma->nr_pages; i++) {
363 			void *addr;
364 
365 			addr = page_address(dma->vaddr_pages[i]);
366 			dma_free_coherent(dma->dev, PAGE_SIZE, addr,
367 					  dma->dma_addr[i]);
368 		}
369 		kfree(dma->dma_addr);
370 		dma->dma_addr = NULL;
371 		kfree(dma->vaddr_pages);
372 		dma->vaddr_pages = NULL;
373 		vunmap(dma->vaddr);
374 		dma->vaddr = NULL;
375 	}
376 
377 	if (dma->bus_addr)
378 		dma->bus_addr = 0;
379 	dma->direction = DMA_NONE;
380 
381 	return 0;
382 }
383 EXPORT_SYMBOL_GPL(videobuf_dma_free);
384 
385 /* --------------------------------------------------------------------- */
386 
387 static void videobuf_vm_open(struct vm_area_struct *vma)
388 {
389 	struct videobuf_mapping *map = vma->vm_private_data;
390 
391 	dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
392 		map->count, vma->vm_start, vma->vm_end);
393 
394 	map->count++;
395 }
396 
397 static void videobuf_vm_close(struct vm_area_struct *vma)
398 {
399 	struct videobuf_mapping *map = vma->vm_private_data;
400 	struct videobuf_queue *q = map->q;
401 	struct videobuf_dma_sg_memory *mem;
402 	int i;
403 
404 	dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
405 		map->count, vma->vm_start, vma->vm_end);
406 
407 	map->count--;
408 	if (0 == map->count) {
409 		dprintk(1, "munmap %p q=%p\n", map, q);
410 		videobuf_queue_lock(q);
411 		for (i = 0; i < VIDEO_MAX_FRAME; i++) {
412 			if (NULL == q->bufs[i])
413 				continue;
414 			mem = q->bufs[i]->priv;
415 			if (!mem)
416 				continue;
417 
418 			MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
419 
420 			if (q->bufs[i]->map != map)
421 				continue;
422 			q->bufs[i]->map   = NULL;
423 			q->bufs[i]->baddr = 0;
424 			q->ops->buf_release(q, q->bufs[i]);
425 		}
426 		videobuf_queue_unlock(q);
427 		kfree(map);
428 	}
429 	return;
430 }
431 
432 /*
433  * Get a anonymous page for the mapping.  Make sure we can DMA to that
434  * memory location with 32bit PCI devices (i.e. don't use highmem for
435  * now ...).  Bounce buffers don't work very well for the data rates
436  * video capture has.
437  */
438 static int videobuf_vm_fault(struct vm_fault *vmf)
439 {
440 	struct vm_area_struct *vma = vmf->vma;
441 	struct page *page;
442 
443 	dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
444 		vmf->address, vma->vm_start, vma->vm_end);
445 
446 	page = alloc_page(GFP_USER | __GFP_DMA32);
447 	if (!page)
448 		return VM_FAULT_OOM;
449 	clear_user_highpage(page, vmf->address);
450 	vmf->page = page;
451 
452 	return 0;
453 }
454 
455 static const struct vm_operations_struct videobuf_vm_ops = {
456 	.open	= videobuf_vm_open,
457 	.close	= videobuf_vm_close,
458 	.fault	= videobuf_vm_fault,
459 };
460 
461 /* ---------------------------------------------------------------------
462  * SG handlers for the generic methods
463  */
464 
465 /* Allocated area consists on 3 parts:
466 	struct video_buffer
467 	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
468 	struct videobuf_dma_sg_memory
469  */
470 
471 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
472 {
473 	struct videobuf_dma_sg_memory *mem;
474 	struct videobuf_buffer *vb;
475 
476 	vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
477 	if (!vb)
478 		return vb;
479 
480 	mem = vb->priv = ((char *)vb) + size;
481 	mem->magic = MAGIC_SG_MEM;
482 
483 	videobuf_dma_init(&mem->dma);
484 
485 	dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
486 		__func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
487 		mem, (long)sizeof(*mem));
488 
489 	return vb;
490 }
491 
492 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
493 {
494 	struct videobuf_dma_sg_memory *mem = buf->priv;
495 	BUG_ON(!mem);
496 
497 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
498 
499 	return mem->dma.vaddr;
500 }
501 
502 static int __videobuf_iolock(struct videobuf_queue *q,
503 			     struct videobuf_buffer *vb,
504 			     struct v4l2_framebuffer *fbuf)
505 {
506 	int err, pages;
507 	dma_addr_t bus;
508 	struct videobuf_dma_sg_memory *mem = vb->priv;
509 	BUG_ON(!mem);
510 
511 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
512 
513 	if (!mem->dma.dev)
514 		mem->dma.dev = q->dev;
515 	else
516 		WARN_ON(mem->dma.dev != q->dev);
517 
518 	switch (vb->memory) {
519 	case V4L2_MEMORY_MMAP:
520 	case V4L2_MEMORY_USERPTR:
521 		if (0 == vb->baddr) {
522 			/* no userspace addr -- kernel bounce buffer */
523 			pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
524 			err = videobuf_dma_init_kernel(&mem->dma,
525 						       DMA_FROM_DEVICE,
526 						       pages);
527 			if (0 != err)
528 				return err;
529 		} else if (vb->memory == V4L2_MEMORY_USERPTR) {
530 			/* dma directly to userspace */
531 			err = videobuf_dma_init_user(&mem->dma,
532 						     DMA_FROM_DEVICE,
533 						     vb->baddr, vb->bsize);
534 			if (0 != err)
535 				return err;
536 		} else {
537 			/* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
538 			buffers can only be called from videobuf_qbuf
539 			we take current->mm->mmap_sem there, to prevent
540 			locking inversion, so don't take it here */
541 
542 			err = videobuf_dma_init_user_locked(&mem->dma,
543 						      DMA_FROM_DEVICE,
544 						      vb->baddr, vb->bsize);
545 			if (0 != err)
546 				return err;
547 		}
548 		break;
549 	case V4L2_MEMORY_OVERLAY:
550 		if (NULL == fbuf)
551 			return -EINVAL;
552 		/* FIXME: need sanity checks for vb->boff */
553 		/*
554 		 * Using a double cast to avoid compiler warnings when
555 		 * building for PAE. Compiler doesn't like direct casting
556 		 * of a 32 bit ptr to 64 bit integer.
557 		 */
558 		bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
559 		pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
560 		err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
561 						bus, pages);
562 		if (0 != err)
563 			return err;
564 		break;
565 	default:
566 		BUG();
567 	}
568 	err = videobuf_dma_map(q->dev, &mem->dma);
569 	if (0 != err)
570 		return err;
571 
572 	return 0;
573 }
574 
575 static int __videobuf_sync(struct videobuf_queue *q,
576 			   struct videobuf_buffer *buf)
577 {
578 	struct videobuf_dma_sg_memory *mem = buf->priv;
579 	BUG_ON(!mem || !mem->dma.sglen);
580 
581 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
582 	MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
583 
584 	dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
585 			    mem->dma.sglen, mem->dma.direction);
586 
587 	return 0;
588 }
589 
590 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
591 				  struct videobuf_buffer *buf,
592 				  struct vm_area_struct *vma)
593 {
594 	struct videobuf_dma_sg_memory *mem = buf->priv;
595 	struct videobuf_mapping *map;
596 	unsigned int first, last, size = 0, i;
597 	int retval;
598 
599 	retval = -EINVAL;
600 
601 	BUG_ON(!mem);
602 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
603 
604 	/* look for first buffer to map */
605 	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
606 		if (buf == q->bufs[first]) {
607 			size = PAGE_ALIGN(q->bufs[first]->bsize);
608 			break;
609 		}
610 	}
611 
612 	/* paranoia, should never happen since buf is always valid. */
613 	if (!size) {
614 		dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
615 				(vma->vm_pgoff << PAGE_SHIFT));
616 		goto done;
617 	}
618 
619 	last = first;
620 
621 	/* create mapping + update buffer list */
622 	retval = -ENOMEM;
623 	map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
624 	if (NULL == map)
625 		goto done;
626 
627 	size = 0;
628 	for (i = first; i <= last; i++) {
629 		if (NULL == q->bufs[i])
630 			continue;
631 		q->bufs[i]->map   = map;
632 		q->bufs[i]->baddr = vma->vm_start + size;
633 		size += PAGE_ALIGN(q->bufs[i]->bsize);
634 	}
635 
636 	map->count    = 1;
637 	map->q        = q;
638 	vma->vm_ops   = &videobuf_vm_ops;
639 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
640 	vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
641 	vma->vm_private_data = map;
642 	dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
643 		map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
644 	retval = 0;
645 
646 done:
647 	return retval;
648 }
649 
650 static struct videobuf_qtype_ops sg_ops = {
651 	.magic        = MAGIC_QTYPE_OPS,
652 
653 	.alloc_vb     = __videobuf_alloc_vb,
654 	.iolock       = __videobuf_iolock,
655 	.sync         = __videobuf_sync,
656 	.mmap_mapper  = __videobuf_mmap_mapper,
657 	.vaddr        = __videobuf_to_vaddr,
658 };
659 
660 void *videobuf_sg_alloc(size_t size)
661 {
662 	struct videobuf_queue q;
663 
664 	/* Required to make generic handler to call __videobuf_alloc */
665 	q.int_ops = &sg_ops;
666 
667 	q.msize = size;
668 
669 	return videobuf_alloc_vb(&q);
670 }
671 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
672 
673 void videobuf_queue_sg_init(struct videobuf_queue *q,
674 			 const struct videobuf_queue_ops *ops,
675 			 struct device *dev,
676 			 spinlock_t *irqlock,
677 			 enum v4l2_buf_type type,
678 			 enum v4l2_field field,
679 			 unsigned int msize,
680 			 void *priv,
681 			 struct mutex *ext_lock)
682 {
683 	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
684 				 priv, &sg_ops, ext_lock);
685 }
686 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
687 
688