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 long first, last;
155 	int err, rw = 0;
156 	unsigned int flags = FOLL_FORCE;
157 
158 	dma->direction = direction;
159 	switch (dma->direction) {
160 	case DMA_FROM_DEVICE:
161 		rw = READ;
162 		break;
163 	case DMA_TO_DEVICE:
164 		rw = WRITE;
165 		break;
166 	default:
167 		BUG();
168 	}
169 
170 	first = (data          & PAGE_MASK) >> PAGE_SHIFT;
171 	last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
172 	dma->offset = data & ~PAGE_MASK;
173 	dma->size = size;
174 	dma->nr_pages = last-first+1;
175 	dma->pages = kmalloc_array(dma->nr_pages, sizeof(struct page *),
176 				   GFP_KERNEL);
177 	if (NULL == dma->pages)
178 		return -ENOMEM;
179 
180 	if (rw == READ)
181 		flags |= FOLL_WRITE;
182 
183 	dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n",
184 		data, size, dma->nr_pages);
185 
186 	err = pin_user_pages(data & PAGE_MASK, dma->nr_pages,
187 			     flags | FOLL_LONGTERM, dma->pages, NULL);
188 
189 	if (err != dma->nr_pages) {
190 		dma->nr_pages = (err >= 0) ? err : 0;
191 		dprintk(1, "pin_user_pages: err=%d [%lu]\n", err,
192 			dma->nr_pages);
193 		return err < 0 ? err : -EINVAL;
194 	}
195 	return 0;
196 }
197 
198 static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
199 			   unsigned long data, unsigned long size)
200 {
201 	int ret;
202 
203 	mmap_read_lock(current->mm);
204 	ret = videobuf_dma_init_user_locked(dma, direction, data, size);
205 	mmap_read_unlock(current->mm);
206 
207 	return ret;
208 }
209 
210 static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
211 				    unsigned long nr_pages)
212 {
213 	int i;
214 
215 	dprintk(1, "init kernel [%lu pages]\n", nr_pages);
216 
217 	dma->direction = direction;
218 	dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
219 				   GFP_KERNEL);
220 	if (!dma->vaddr_pages)
221 		return -ENOMEM;
222 
223 	dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
224 	if (!dma->dma_addr) {
225 		kfree(dma->vaddr_pages);
226 		return -ENOMEM;
227 	}
228 	for (i = 0; i < nr_pages; i++) {
229 		void *addr;
230 
231 		addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
232 					  &(dma->dma_addr[i]), GFP_KERNEL);
233 		if (addr == NULL)
234 			goto out_free_pages;
235 
236 		dma->vaddr_pages[i] = virt_to_page(addr);
237 	}
238 	dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
239 			  PAGE_KERNEL);
240 	if (NULL == dma->vaddr) {
241 		dprintk(1, "vmalloc_32(%lu pages) failed\n", nr_pages);
242 		goto out_free_pages;
243 	}
244 
245 	dprintk(1, "vmalloc is at addr %p, size=%lu\n",
246 		dma->vaddr, 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, unsigned long nr_pages)
271 {
272 	dprintk(1, "init overlay [%lu 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->nr_pages, 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 		unpin_user_pages_dirty_lock(dma->pages, dma->nr_pages,
353 					    dma->direction == DMA_FROM_DEVICE);
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 vm_fault_t videobuf_vm_fault(struct vm_fault *vmf)
436 {
437 	struct vm_area_struct *vma = vmf->vma;
438 	struct page *page;
439 
440 	dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
441 		vmf->address, 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, vmf->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 	struct videobuf_dma_sg_memory *mem = vb->priv;
504 	unsigned long pages;
505 	dma_addr_t bus;
506 	int err;
507 
508 	BUG_ON(!mem);
509 
510 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
511 
512 	if (!mem->dma.dev)
513 		mem->dma.dev = q->dev;
514 	else
515 		WARN_ON(mem->dma.dev != q->dev);
516 
517 	switch (vb->memory) {
518 	case V4L2_MEMORY_MMAP:
519 	case V4L2_MEMORY_USERPTR:
520 		if (0 == vb->baddr) {
521 			/* no userspace addr -- kernel bounce buffer */
522 			pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
523 			err = videobuf_dma_init_kernel(&mem->dma,
524 						       DMA_FROM_DEVICE,
525 						       pages);
526 			if (0 != err)
527 				return err;
528 		} else if (vb->memory == V4L2_MEMORY_USERPTR) {
529 			/* dma directly to userspace */
530 			err = videobuf_dma_init_user(&mem->dma,
531 						     DMA_FROM_DEVICE,
532 						     vb->baddr, vb->bsize);
533 			if (0 != err)
534 				return err;
535 		} else {
536 			/* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
537 			buffers can only be called from videobuf_qbuf
538 			we take current->mm->mmap_lock there, to prevent
539 			locking inversion, so don't take it here */
540 
541 			err = videobuf_dma_init_user_locked(&mem->dma,
542 						      DMA_FROM_DEVICE,
543 						      vb->baddr, vb->bsize);
544 			if (0 != err)
545 				return err;
546 		}
547 		break;
548 	case V4L2_MEMORY_OVERLAY:
549 		if (NULL == fbuf)
550 			return -EINVAL;
551 		/* FIXME: need sanity checks for vb->boff */
552 		/*
553 		 * Using a double cast to avoid compiler warnings when
554 		 * building for PAE. Compiler doesn't like direct casting
555 		 * of a 32 bit ptr to 64 bit integer.
556 		 */
557 		bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
558 		pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
559 		err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
560 						bus, pages);
561 		if (0 != err)
562 			return err;
563 		break;
564 	default:
565 		BUG();
566 	}
567 	err = videobuf_dma_map(q->dev, &mem->dma);
568 	if (0 != err)
569 		return err;
570 
571 	return 0;
572 }
573 
574 static int __videobuf_sync(struct videobuf_queue *q,
575 			   struct videobuf_buffer *buf)
576 {
577 	struct videobuf_dma_sg_memory *mem = buf->priv;
578 	BUG_ON(!mem || !mem->dma.sglen);
579 
580 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
581 	MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
582 
583 	dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
584 			    mem->dma.nr_pages, mem->dma.direction);
585 
586 	return 0;
587 }
588 
589 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
590 				  struct videobuf_buffer *buf,
591 				  struct vm_area_struct *vma)
592 {
593 	struct videobuf_dma_sg_memory *mem = buf->priv;
594 	struct videobuf_mapping *map;
595 	unsigned int first, last, size = 0, i;
596 	int retval;
597 
598 	retval = -EINVAL;
599 
600 	BUG_ON(!mem);
601 	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
602 
603 	/* look for first buffer to map */
604 	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
605 		if (buf == q->bufs[first]) {
606 			size = PAGE_ALIGN(q->bufs[first]->bsize);
607 			break;
608 		}
609 	}
610 
611 	/* paranoia, should never happen since buf is always valid. */
612 	if (!size) {
613 		dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
614 				(vma->vm_pgoff << PAGE_SHIFT));
615 		goto done;
616 	}
617 
618 	last = first;
619 
620 	/* create mapping + update buffer list */
621 	retval = -ENOMEM;
622 	map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
623 	if (NULL == map)
624 		goto done;
625 
626 	size = 0;
627 	for (i = first; i <= last; i++) {
628 		if (NULL == q->bufs[i])
629 			continue;
630 		q->bufs[i]->map   = map;
631 		q->bufs[i]->baddr = vma->vm_start + size;
632 		size += PAGE_ALIGN(q->bufs[i]->bsize);
633 	}
634 
635 	map->count    = 1;
636 	map->q        = q;
637 	vma->vm_ops   = &videobuf_vm_ops;
638 	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
639 	vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
640 	vma->vm_private_data = map;
641 	dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
642 		map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
643 	retval = 0;
644 
645 done:
646 	return retval;
647 }
648 
649 static struct videobuf_qtype_ops sg_ops = {
650 	.magic        = MAGIC_QTYPE_OPS,
651 
652 	.alloc_vb     = __videobuf_alloc_vb,
653 	.iolock       = __videobuf_iolock,
654 	.sync         = __videobuf_sync,
655 	.mmap_mapper  = __videobuf_mmap_mapper,
656 	.vaddr        = __videobuf_to_vaddr,
657 };
658 
659 void *videobuf_sg_alloc(size_t size)
660 {
661 	struct videobuf_queue q;
662 
663 	/* Required to make generic handler to call __videobuf_alloc */
664 	q.int_ops = &sg_ops;
665 
666 	q.msize = size;
667 
668 	return videobuf_alloc_vb(&q);
669 }
670 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
671 
672 void videobuf_queue_sg_init(struct videobuf_queue *q,
673 			 const struct videobuf_queue_ops *ops,
674 			 struct device *dev,
675 			 spinlock_t *irqlock,
676 			 enum v4l2_buf_type type,
677 			 enum v4l2_field field,
678 			 unsigned int msize,
679 			 void *priv,
680 			 struct mutex *ext_lock)
681 {
682 	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
683 				 priv, &sg_ops, ext_lock);
684 }
685 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
686 
687