1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * helper functions for SG DMA video4linux capture buffers
4  *
5  * The functions expect the hardware being able to scatter gather
6  * (i.e. the buffers are not linear in physical memory, but fragmented
7  * into PAGE_SIZE chunks).  They also assume the driver does not need
8  * to touch the video data.
9  *
10  * (c) 2007 Mauro Carvalho Chehab, <mchehab@kernel.org>
11  *
12  * Highly based on video-buf written originally by:
13  * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
14  * (c) 2006 Mauro Carvalho Chehab, <mchehab@kernel.org>
15  * (c) 2006 Ted Walther and John Sokol
16  */
17 
18 #include <linux/init.h>
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/sched/mm.h>
22 #include <linux/slab.h>
23 #include <linux/interrupt.h>
24 #include <linux/pgtable.h>
25 
26 #include <linux/dma-mapping.h>
27 #include <linux/vmalloc.h>
28 #include <linux/pagemap.h>
29 #include <linux/scatterlist.h>
30 #include <asm/page.h>
31 
32 #include <media/videobuf-dma-sg.h>
33 
34 #define MAGIC_DMABUF 0x19721112
35 #define MAGIC_SG_MEM 0x17890714
36 
37 #define MAGIC_CHECK(is, should)						\
38 	if (unlikely((is) != (should))) {				\
39 		printk(KERN_ERR "magic mismatch: %x (expected %x)\n",	\
40 				is, should);				\
41 		BUG();							\
42 	}
43 
44 static int debug;
45 module_param(debug, int, 0644);
46 
47 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
48 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@kernel.org>");
49 MODULE_LICENSE("GPL");
50 
51 #define dprintk(level, fmt, arg...)					\
52 	if (debug >= level)						\
53 		printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
54 
55 /* --------------------------------------------------------------------- */
56 
57 /*
58  * Return a scatterlist for some page-aligned vmalloc()'ed memory
59  * block (NULL on errors).  Memory for the scatterlist is allocated
60  * using kmalloc.  The caller must free the memory.
61  */
62 static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
63 						  int nr_pages)
64 {
65 	struct scatterlist *sglist;
66 	struct page *pg;
67 	int i;
68 
69 	sglist = vzalloc(array_size(nr_pages, sizeof(*sglist)));
70 	if (NULL == sglist)
71 		return NULL;
72 	sg_init_table(sglist, nr_pages);
73 	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
74 		pg = vmalloc_to_page(virt);
75 		if (NULL == pg)
76 			goto err;
77 		BUG_ON(PageHighMem(pg));
78 		sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
79 	}
80 	return sglist;
81 
82 err:
83 	vfree(sglist);
84 	return NULL;
85 }
86 
87 /*
88  * Return a scatterlist for a an array of userpages (NULL on errors).
89  * Memory for the scatterlist is allocated using kmalloc.  The caller
90  * must free the memory.
91  */
92 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
93 					int nr_pages, int offset, size_t size)
94 {
95 	struct scatterlist *sglist;
96 	int i;
97 
98 	if (NULL == pages[0])
99 		return NULL;
100 	sglist = vmalloc(array_size(nr_pages, sizeof(*sglist)));
101 	if (NULL == sglist)
102 		return NULL;
103 	sg_init_table(sglist, nr_pages);
104 
105 	if (PageHighMem(pages[0]))
106 		/* DMA to highmem pages might not work */
107 		goto highmem;
108 	sg_set_page(&sglist[0], pages[0],
109 			min_t(size_t, PAGE_SIZE - offset, size), offset);
110 	size -= min_t(size_t, PAGE_SIZE - offset, size);
111 	for (i = 1; i < nr_pages; i++) {
112 		if (NULL == pages[i])
113 			goto nopage;
114 		if (PageHighMem(pages[i]))
115 			goto highmem;
116 		sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
117 		size -= min_t(size_t, PAGE_SIZE, size);
118 	}
119 	return sglist;
120 
121 nopage:
122 	dprintk(2, "sgl: oops - no page\n");
123 	vfree(sglist);
124 	return NULL;
125 
126 highmem:
127 	dprintk(2, "sgl: oops - highmem page\n");
128 	vfree(sglist);
129 	return NULL;
130 }
131 
132 /* --------------------------------------------------------------------- */
133 
134 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
135 {
136 	struct videobuf_dma_sg_memory *mem = buf->priv;
137 	BUG_ON(!mem);
138 
139 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
140 
141 	return &mem->dma;
142 }
143 EXPORT_SYMBOL_GPL(videobuf_to_dma);
144 
145 static void videobuf_dma_init(struct videobuf_dmabuf *dma)
146 {
147 	memset(dma, 0, sizeof(*dma));
148 	dma->magic = MAGIC_DMABUF;
149 }
150 
151 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
152 			int direction, unsigned long data, unsigned long size)
153 {
154 	unsigned int gup_flags = FOLL_LONGTERM;
155 	unsigned long first, last;
156 	int err;
157 
158 	dma->direction = direction;
159 	switch (dma->direction) {
160 	case DMA_FROM_DEVICE:
161 		gup_flags |= FOLL_WRITE;
162 		break;
163 	case DMA_TO_DEVICE:
164 		break;
165 	default:
166 		BUG();
167 	}
168 
169 	first = (data          & PAGE_MASK) >> PAGE_SHIFT;
170 	last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
171 	dma->offset = data & ~PAGE_MASK;
172 	dma->size = size;
173 	dma->nr_pages = last-first+1;
174 	dma->pages = kmalloc_array(dma->nr_pages, sizeof(struct page *),
175 				   GFP_KERNEL);
176 	if (NULL == dma->pages)
177 		return -ENOMEM;
178 
179 	dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n",
180 		data, size, dma->nr_pages);
181 
182 	err = pin_user_pages(data & PAGE_MASK, dma->nr_pages, gup_flags,
183 			     dma->pages, NULL);
184 
185 	if (err != dma->nr_pages) {
186 		dma->nr_pages = (err >= 0) ? err : 0;
187 		dprintk(1, "pin_user_pages: err=%d [%lu]\n", err,
188 			dma->nr_pages);
189 		return err < 0 ? err : -EINVAL;
190 	}
191 	return 0;
192 }
193 
194 static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
195 			   unsigned long data, unsigned long size)
196 {
197 	int ret;
198 
199 	mmap_read_lock(current->mm);
200 	ret = videobuf_dma_init_user_locked(dma, direction, data, size);
201 	mmap_read_unlock(current->mm);
202 
203 	return ret;
204 }
205 
206 static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
207 				    unsigned long nr_pages)
208 {
209 	int i;
210 
211 	dprintk(1, "init kernel [%lu pages]\n", nr_pages);
212 
213 	dma->direction = direction;
214 	dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
215 				   GFP_KERNEL);
216 	if (!dma->vaddr_pages)
217 		return -ENOMEM;
218 
219 	dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
220 	if (!dma->dma_addr) {
221 		kfree(dma->vaddr_pages);
222 		return -ENOMEM;
223 	}
224 	for (i = 0; i < nr_pages; i++) {
225 		void *addr;
226 
227 		addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
228 					  &(dma->dma_addr[i]), GFP_KERNEL);
229 		if (addr == NULL)
230 			goto out_free_pages;
231 
232 		dma->vaddr_pages[i] = virt_to_page(addr);
233 	}
234 	dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
235 			  PAGE_KERNEL);
236 	if (NULL == dma->vaddr) {
237 		dprintk(1, "vmalloc_32(%lu pages) failed\n", nr_pages);
238 		goto out_free_pages;
239 	}
240 
241 	dprintk(1, "vmalloc is at addr %p, size=%lu\n",
242 		dma->vaddr, nr_pages << PAGE_SHIFT);
243 
244 	memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
245 	dma->nr_pages = nr_pages;
246 
247 	return 0;
248 out_free_pages:
249 	while (i > 0) {
250 		void *addr;
251 
252 		i--;
253 		addr = page_address(dma->vaddr_pages[i]);
254 		dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
255 	}
256 	kfree(dma->dma_addr);
257 	dma->dma_addr = NULL;
258 	kfree(dma->vaddr_pages);
259 	dma->vaddr_pages = NULL;
260 
261 	return -ENOMEM;
262 
263 }
264 
265 static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
266 			      dma_addr_t addr, unsigned long nr_pages)
267 {
268 	dprintk(1, "init overlay [%lu pages @ bus 0x%lx]\n",
269 		nr_pages, (unsigned long)addr);
270 	dma->direction = direction;
271 
272 	if (0 == addr)
273 		return -EINVAL;
274 
275 	dma->bus_addr = addr;
276 	dma->nr_pages = nr_pages;
277 
278 	return 0;
279 }
280 
281 static int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
282 {
283 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
284 	BUG_ON(0 == dma->nr_pages);
285 
286 	if (dma->pages) {
287 		dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
288 						   dma->offset, dma->size);
289 	}
290 	if (dma->vaddr) {
291 		dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
292 						     dma->nr_pages);
293 	}
294 	if (dma->bus_addr) {
295 		dma->sglist = vmalloc(sizeof(*dma->sglist));
296 		if (NULL != dma->sglist) {
297 			dma->sglen = 1;
298 			sg_dma_address(&dma->sglist[0])	= dma->bus_addr
299 							& PAGE_MASK;
300 			dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
301 			sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
302 		}
303 	}
304 	if (NULL == dma->sglist) {
305 		dprintk(1, "scatterlist is NULL\n");
306 		return -ENOMEM;
307 	}
308 	if (!dma->bus_addr) {
309 		dma->sglen = dma_map_sg(dev, dma->sglist,
310 					dma->nr_pages, dma->direction);
311 		if (0 == dma->sglen) {
312 			printk(KERN_WARNING
313 			       "%s: videobuf_map_sg failed\n", __func__);
314 			vfree(dma->sglist);
315 			dma->sglist = NULL;
316 			dma->sglen = 0;
317 			return -ENOMEM;
318 		}
319 	}
320 
321 	return 0;
322 }
323 
324 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
325 {
326 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
327 
328 	if (!dma->sglen)
329 		return 0;
330 
331 	dma_unmap_sg(dev, dma->sglist, dma->nr_pages, dma->direction);
332 
333 	vfree(dma->sglist);
334 	dma->sglist = NULL;
335 	dma->sglen = 0;
336 
337 	return 0;
338 }
339 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
340 
341 int videobuf_dma_free(struct videobuf_dmabuf *dma)
342 {
343 	int i;
344 	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
345 	BUG_ON(dma->sglen);
346 
347 	if (dma->pages) {
348 		unpin_user_pages_dirty_lock(dma->pages, dma->nr_pages,
349 					    dma->direction == DMA_FROM_DEVICE);
350 		kfree(dma->pages);
351 		dma->pages = NULL;
352 	}
353 
354 	if (dma->dma_addr) {
355 		for (i = 0; i < dma->nr_pages; i++) {
356 			void *addr;
357 
358 			addr = page_address(dma->vaddr_pages[i]);
359 			dma_free_coherent(dma->dev, PAGE_SIZE, addr,
360 					  dma->dma_addr[i]);
361 		}
362 		kfree(dma->dma_addr);
363 		dma->dma_addr = NULL;
364 		kfree(dma->vaddr_pages);
365 		dma->vaddr_pages = NULL;
366 		vunmap(dma->vaddr);
367 		dma->vaddr = NULL;
368 	}
369 
370 	if (dma->bus_addr)
371 		dma->bus_addr = 0;
372 	dma->direction = DMA_NONE;
373 
374 	return 0;
375 }
376 EXPORT_SYMBOL_GPL(videobuf_dma_free);
377 
378 /* --------------------------------------------------------------------- */
379 
380 static void videobuf_vm_open(struct vm_area_struct *vma)
381 {
382 	struct videobuf_mapping *map = vma->vm_private_data;
383 
384 	dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
385 		map->count, vma->vm_start, vma->vm_end);
386 
387 	map->count++;
388 }
389 
390 static void videobuf_vm_close(struct vm_area_struct *vma)
391 {
392 	struct videobuf_mapping *map = vma->vm_private_data;
393 	struct videobuf_queue *q = map->q;
394 	struct videobuf_dma_sg_memory *mem;
395 	int i;
396 
397 	dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
398 		map->count, vma->vm_start, vma->vm_end);
399 
400 	map->count--;
401 	if (0 == map->count) {
402 		dprintk(1, "munmap %p q=%p\n", map, q);
403 		videobuf_queue_lock(q);
404 		for (i = 0; i < VIDEO_MAX_FRAME; i++) {
405 			if (NULL == q->bufs[i])
406 				continue;
407 			mem = q->bufs[i]->priv;
408 			if (!mem)
409 				continue;
410 
411 			MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
412 
413 			if (q->bufs[i]->map != map)
414 				continue;
415 			q->bufs[i]->map   = NULL;
416 			q->bufs[i]->baddr = 0;
417 			q->ops->buf_release(q, q->bufs[i]);
418 		}
419 		videobuf_queue_unlock(q);
420 		kfree(map);
421 	}
422 }
423 
424 /*
425  * Get a anonymous page for the mapping.  Make sure we can DMA to that
426  * memory location with 32bit PCI devices (i.e. don't use highmem for
427  * now ...).  Bounce buffers don't work very well for the data rates
428  * video capture has.
429  */
430 static vm_fault_t videobuf_vm_fault(struct vm_fault *vmf)
431 {
432 	struct vm_area_struct *vma = vmf->vma;
433 	struct page *page;
434 
435 	dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
436 		vmf->address, vma->vm_start, vma->vm_end);
437 
438 	page = alloc_page(GFP_USER | __GFP_DMA32);
439 	if (!page)
440 		return VM_FAULT_OOM;
441 	clear_user_highpage(page, vmf->address);
442 	vmf->page = page;
443 
444 	return 0;
445 }
446 
447 static const struct vm_operations_struct videobuf_vm_ops = {
448 	.open	= videobuf_vm_open,
449 	.close	= videobuf_vm_close,
450 	.fault	= videobuf_vm_fault,
451 };
452 
453 /* ---------------------------------------------------------------------
454  * SG handlers for the generic methods
455  */
456 
457 /* Allocated area consists on 3 parts:
458 	struct video_buffer
459 	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
460 	struct videobuf_dma_sg_memory
461  */
462 
463 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
464 {
465 	struct videobuf_dma_sg_memory *mem;
466 	struct videobuf_buffer *vb;
467 
468 	vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
469 	if (!vb)
470 		return vb;
471 
472 	mem = vb->priv = ((char *)vb) + size;
473 	mem->magic = MAGIC_SG_MEM;
474 
475 	videobuf_dma_init(&mem->dma);
476 
477 	dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
478 		__func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
479 		mem, (long)sizeof(*mem));
480 
481 	return vb;
482 }
483 
484 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
485 {
486 	struct videobuf_dma_sg_memory *mem = buf->priv;
487 	BUG_ON(!mem);
488 
489 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
490 
491 	return mem->dma.vaddr;
492 }
493 
494 static int __videobuf_iolock(struct videobuf_queue *q,
495 			     struct videobuf_buffer *vb,
496 			     struct v4l2_framebuffer *fbuf)
497 {
498 	struct videobuf_dma_sg_memory *mem = vb->priv;
499 	unsigned long pages;
500 	dma_addr_t bus;
501 	int err;
502 
503 	BUG_ON(!mem);
504 
505 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
506 
507 	if (!mem->dma.dev)
508 		mem->dma.dev = q->dev;
509 	else
510 		WARN_ON(mem->dma.dev != q->dev);
511 
512 	switch (vb->memory) {
513 	case V4L2_MEMORY_MMAP:
514 	case V4L2_MEMORY_USERPTR:
515 		if (0 == vb->baddr) {
516 			/* no userspace addr -- kernel bounce buffer */
517 			pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
518 			err = videobuf_dma_init_kernel(&mem->dma,
519 						       DMA_FROM_DEVICE,
520 						       pages);
521 			if (0 != err)
522 				return err;
523 		} else if (vb->memory == V4L2_MEMORY_USERPTR) {
524 			/* dma directly to userspace */
525 			err = videobuf_dma_init_user(&mem->dma,
526 						     DMA_FROM_DEVICE,
527 						     vb->baddr, vb->bsize);
528 			if (0 != err)
529 				return err;
530 		} else {
531 			/* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
532 			buffers can only be called from videobuf_qbuf
533 			we take current->mm->mmap_lock there, to prevent
534 			locking inversion, so don't take it here */
535 
536 			err = videobuf_dma_init_user_locked(&mem->dma,
537 						      DMA_FROM_DEVICE,
538 						      vb->baddr, vb->bsize);
539 			if (0 != err)
540 				return err;
541 		}
542 		break;
543 	case V4L2_MEMORY_OVERLAY:
544 		if (NULL == fbuf)
545 			return -EINVAL;
546 		/* FIXME: need sanity checks for vb->boff */
547 		/*
548 		 * Using a double cast to avoid compiler warnings when
549 		 * building for PAE. Compiler doesn't like direct casting
550 		 * of a 32 bit ptr to 64 bit integer.
551 		 */
552 		bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
553 		pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
554 		err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
555 						bus, pages);
556 		if (0 != err)
557 			return err;
558 		break;
559 	default:
560 		BUG();
561 	}
562 	err = videobuf_dma_map(q->dev, &mem->dma);
563 	if (0 != err)
564 		return err;
565 
566 	return 0;
567 }
568 
569 static int __videobuf_sync(struct videobuf_queue *q,
570 			   struct videobuf_buffer *buf)
571 {
572 	struct videobuf_dma_sg_memory *mem = buf->priv;
573 	BUG_ON(!mem || !mem->dma.sglen);
574 
575 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
576 	MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
577 
578 	dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
579 			    mem->dma.nr_pages, mem->dma.direction);
580 
581 	return 0;
582 }
583 
584 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
585 				  struct videobuf_buffer *buf,
586 				  struct vm_area_struct *vma)
587 {
588 	struct videobuf_dma_sg_memory *mem = buf->priv;
589 	struct videobuf_mapping *map;
590 	unsigned int first, last, size = 0, i;
591 	int retval;
592 
593 	retval = -EINVAL;
594 
595 	BUG_ON(!mem);
596 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
597 
598 	/* look for first buffer to map */
599 	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
600 		if (buf == q->bufs[first]) {
601 			size = PAGE_ALIGN(q->bufs[first]->bsize);
602 			break;
603 		}
604 	}
605 
606 	/* paranoia, should never happen since buf is always valid. */
607 	if (!size) {
608 		dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
609 				(vma->vm_pgoff << PAGE_SHIFT));
610 		goto done;
611 	}
612 
613 	last = first;
614 
615 	/* create mapping + update buffer list */
616 	retval = -ENOMEM;
617 	map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
618 	if (NULL == map)
619 		goto done;
620 
621 	size = 0;
622 	for (i = first; i <= last; i++) {
623 		if (NULL == q->bufs[i])
624 			continue;
625 		q->bufs[i]->map   = map;
626 		q->bufs[i]->baddr = vma->vm_start + size;
627 		size += PAGE_ALIGN(q->bufs[i]->bsize);
628 	}
629 
630 	map->count    = 1;
631 	map->q        = q;
632 	vma->vm_ops   = &videobuf_vm_ops;
633 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
634 	vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
635 	vma->vm_private_data = map;
636 	dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
637 		map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
638 	retval = 0;
639 
640 done:
641 	return retval;
642 }
643 
644 static struct videobuf_qtype_ops sg_ops = {
645 	.magic        = MAGIC_QTYPE_OPS,
646 
647 	.alloc_vb     = __videobuf_alloc_vb,
648 	.iolock       = __videobuf_iolock,
649 	.sync         = __videobuf_sync,
650 	.mmap_mapper  = __videobuf_mmap_mapper,
651 	.vaddr        = __videobuf_to_vaddr,
652 };
653 
654 void *videobuf_sg_alloc(size_t size)
655 {
656 	struct videobuf_queue q;
657 
658 	/* Required to make generic handler to call __videobuf_alloc */
659 	q.int_ops = &sg_ops;
660 
661 	q.msize = size;
662 
663 	return videobuf_alloc_vb(&q);
664 }
665 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
666 
667 void videobuf_queue_sg_init(struct videobuf_queue *q,
668 			 const struct videobuf_queue_ops *ops,
669 			 struct device *dev,
670 			 spinlock_t *irqlock,
671 			 enum v4l2_buf_type type,
672 			 enum v4l2_field field,
673 			 unsigned int msize,
674 			 void *priv,
675 			 struct mutex *ext_lock)
676 {
677 	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
678 				 priv, &sg_ops, ext_lock);
679 }
680 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
681 
682