1 /*
2  * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
3  *
4  * Copyright (C) 2010 Samsung Electronics
5  *
6  * Author: Andrzej Pietrasiewicz <andrzejtp2010@gmail.com>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation.
11  */
12 
13 #include <linux/module.h>
14 #include <linux/mm.h>
15 #include <linux/refcount.h>
16 #include <linux/scatterlist.h>
17 #include <linux/sched.h>
18 #include <linux/slab.h>
19 #include <linux/vmalloc.h>
20 
21 #include <media/videobuf2-v4l2.h>
22 #include <media/videobuf2-memops.h>
23 #include <media/videobuf2-dma-sg.h>
24 
25 static int debug;
26 module_param(debug, int, 0644);
27 
28 #define dprintk(level, fmt, arg...)					\
29 	do {								\
30 		if (debug >= level)					\
31 			printk(KERN_DEBUG "vb2-dma-sg: " fmt, ## arg);	\
32 	} while (0)
33 
34 struct vb2_dma_sg_buf {
35 	struct device			*dev;
36 	void				*vaddr;
37 	struct page			**pages;
38 	struct frame_vector		*vec;
39 	int				offset;
40 	enum dma_data_direction		dma_dir;
41 	struct sg_table			sg_table;
42 	/*
43 	 * This will point to sg_table when used with the MMAP or USERPTR
44 	 * memory model, and to the dma_buf sglist when used with the
45 	 * DMABUF memory model.
46 	 */
47 	struct sg_table			*dma_sgt;
48 	size_t				size;
49 	unsigned int			num_pages;
50 	refcount_t			refcount;
51 	struct vb2_vmarea_handler	handler;
52 
53 	struct dma_buf_attachment	*db_attach;
54 };
55 
56 static void vb2_dma_sg_put(void *buf_priv);
57 
58 static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
59 		gfp_t gfp_flags)
60 {
61 	unsigned int last_page = 0;
62 	unsigned long size = buf->size;
63 
64 	while (size > 0) {
65 		struct page *pages;
66 		int order;
67 		int i;
68 
69 		order = get_order(size);
70 		/* Don't over allocate*/
71 		if ((PAGE_SIZE << order) > size)
72 			order--;
73 
74 		pages = NULL;
75 		while (!pages) {
76 			pages = alloc_pages(GFP_KERNEL | __GFP_ZERO |
77 					__GFP_NOWARN | gfp_flags, order);
78 			if (pages)
79 				break;
80 
81 			if (order == 0) {
82 				while (last_page--)
83 					__free_page(buf->pages[last_page]);
84 				return -ENOMEM;
85 			}
86 			order--;
87 		}
88 
89 		split_page(pages, order);
90 		for (i = 0; i < (1 << order); i++)
91 			buf->pages[last_page++] = &pages[i];
92 
93 		size -= PAGE_SIZE << order;
94 	}
95 
96 	return 0;
97 }
98 
99 static void *vb2_dma_sg_alloc(struct device *dev, unsigned long dma_attrs,
100 			      unsigned long size, enum dma_data_direction dma_dir,
101 			      gfp_t gfp_flags)
102 {
103 	struct vb2_dma_sg_buf *buf;
104 	struct sg_table *sgt;
105 	int ret;
106 	int num_pages;
107 
108 	if (WARN_ON(!dev))
109 		return ERR_PTR(-EINVAL);
110 
111 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
112 	if (!buf)
113 		return ERR_PTR(-ENOMEM);
114 
115 	buf->vaddr = NULL;
116 	buf->dma_dir = dma_dir;
117 	buf->offset = 0;
118 	buf->size = size;
119 	/* size is already page aligned */
120 	buf->num_pages = size >> PAGE_SHIFT;
121 	buf->dma_sgt = &buf->sg_table;
122 
123 	/*
124 	 * NOTE: dma-sg allocates memory using the page allocator directly, so
125 	 * there is no memory consistency guarantee, hence dma-sg ignores DMA
126 	 * attributes passed from the upper layer.
127 	 */
128 	buf->pages = kvmalloc_array(buf->num_pages, sizeof(struct page *),
129 				    GFP_KERNEL | __GFP_ZERO);
130 	if (!buf->pages)
131 		goto fail_pages_array_alloc;
132 
133 	ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags);
134 	if (ret)
135 		goto fail_pages_alloc;
136 
137 	ret = sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
138 			buf->num_pages, 0, size, GFP_KERNEL);
139 	if (ret)
140 		goto fail_table_alloc;
141 
142 	/* Prevent the device from being released while the buffer is used */
143 	buf->dev = get_device(dev);
144 
145 	sgt = &buf->sg_table;
146 	/*
147 	 * No need to sync to the device, this will happen later when the
148 	 * prepare() memop is called.
149 	 */
150 	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
151 			    DMA_ATTR_SKIP_CPU_SYNC))
152 		goto fail_map;
153 
154 	buf->handler.refcount = &buf->refcount;
155 	buf->handler.put = vb2_dma_sg_put;
156 	buf->handler.arg = buf;
157 
158 	refcount_set(&buf->refcount, 1);
159 
160 	dprintk(1, "%s: Allocated buffer of %d pages\n",
161 		__func__, buf->num_pages);
162 	return buf;
163 
164 fail_map:
165 	put_device(buf->dev);
166 	sg_free_table(buf->dma_sgt);
167 fail_table_alloc:
168 	num_pages = buf->num_pages;
169 	while (num_pages--)
170 		__free_page(buf->pages[num_pages]);
171 fail_pages_alloc:
172 	kvfree(buf->pages);
173 fail_pages_array_alloc:
174 	kfree(buf);
175 	return ERR_PTR(-ENOMEM);
176 }
177 
178 static void vb2_dma_sg_put(void *buf_priv)
179 {
180 	struct vb2_dma_sg_buf *buf = buf_priv;
181 	struct sg_table *sgt = &buf->sg_table;
182 	int i = buf->num_pages;
183 
184 	if (refcount_dec_and_test(&buf->refcount)) {
185 		dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
186 			buf->num_pages);
187 		dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir,
188 				  DMA_ATTR_SKIP_CPU_SYNC);
189 		if (buf->vaddr)
190 			vm_unmap_ram(buf->vaddr, buf->num_pages);
191 		sg_free_table(buf->dma_sgt);
192 		while (--i >= 0)
193 			__free_page(buf->pages[i]);
194 		kvfree(buf->pages);
195 		put_device(buf->dev);
196 		kfree(buf);
197 	}
198 }
199 
200 static void vb2_dma_sg_prepare(void *buf_priv)
201 {
202 	struct vb2_dma_sg_buf *buf = buf_priv;
203 	struct sg_table *sgt = buf->dma_sgt;
204 
205 	dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
206 }
207 
208 static void vb2_dma_sg_finish(void *buf_priv)
209 {
210 	struct vb2_dma_sg_buf *buf = buf_priv;
211 	struct sg_table *sgt = buf->dma_sgt;
212 
213 	dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
214 }
215 
216 static void *vb2_dma_sg_get_userptr(struct device *dev, unsigned long vaddr,
217 				    unsigned long size,
218 				    enum dma_data_direction dma_dir)
219 {
220 	struct vb2_dma_sg_buf *buf;
221 	struct sg_table *sgt;
222 	struct frame_vector *vec;
223 
224 	if (WARN_ON(!dev))
225 		return ERR_PTR(-EINVAL);
226 
227 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
228 	if (!buf)
229 		return ERR_PTR(-ENOMEM);
230 
231 	buf->vaddr = NULL;
232 	buf->dev = dev;
233 	buf->dma_dir = dma_dir;
234 	buf->offset = vaddr & ~PAGE_MASK;
235 	buf->size = size;
236 	buf->dma_sgt = &buf->sg_table;
237 	vec = vb2_create_framevec(vaddr, size);
238 	if (IS_ERR(vec))
239 		goto userptr_fail_pfnvec;
240 	buf->vec = vec;
241 
242 	buf->pages = frame_vector_pages(vec);
243 	if (IS_ERR(buf->pages))
244 		goto userptr_fail_sgtable;
245 	buf->num_pages = frame_vector_count(vec);
246 
247 	if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
248 			buf->num_pages, buf->offset, size, 0))
249 		goto userptr_fail_sgtable;
250 
251 	sgt = &buf->sg_table;
252 	/*
253 	 * No need to sync to the device, this will happen later when the
254 	 * prepare() memop is called.
255 	 */
256 	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
257 			    DMA_ATTR_SKIP_CPU_SYNC))
258 		goto userptr_fail_map;
259 
260 	return buf;
261 
262 userptr_fail_map:
263 	sg_free_table(&buf->sg_table);
264 userptr_fail_sgtable:
265 	vb2_destroy_framevec(vec);
266 userptr_fail_pfnvec:
267 	kfree(buf);
268 	return ERR_PTR(-ENOMEM);
269 }
270 
271 /*
272  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
273  *		 be used
274  */
275 static void vb2_dma_sg_put_userptr(void *buf_priv)
276 {
277 	struct vb2_dma_sg_buf *buf = buf_priv;
278 	struct sg_table *sgt = &buf->sg_table;
279 	int i = buf->num_pages;
280 
281 	dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
282 	       __func__, buf->num_pages);
283 	dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
284 	if (buf->vaddr)
285 		vm_unmap_ram(buf->vaddr, buf->num_pages);
286 	sg_free_table(buf->dma_sgt);
287 	if (buf->dma_dir == DMA_FROM_DEVICE ||
288 	    buf->dma_dir == DMA_BIDIRECTIONAL)
289 		while (--i >= 0)
290 			set_page_dirty_lock(buf->pages[i]);
291 	vb2_destroy_framevec(buf->vec);
292 	kfree(buf);
293 }
294 
295 static void *vb2_dma_sg_vaddr(void *buf_priv)
296 {
297 	struct vb2_dma_sg_buf *buf = buf_priv;
298 	struct dma_buf_map map;
299 	int ret;
300 
301 	BUG_ON(!buf);
302 
303 	if (!buf->vaddr) {
304 		if (buf->db_attach) {
305 			ret = dma_buf_vmap(buf->db_attach->dmabuf, &map);
306 			buf->vaddr = ret ? NULL : map.vaddr;
307 		} else {
308 			buf->vaddr = vm_map_ram(buf->pages, buf->num_pages, -1);
309 		}
310 	}
311 
312 	/* add offset in case userptr is not page-aligned */
313 	return buf->vaddr ? buf->vaddr + buf->offset : NULL;
314 }
315 
316 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
317 {
318 	struct vb2_dma_sg_buf *buf = buf_priv;
319 
320 	return refcount_read(&buf->refcount);
321 }
322 
323 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
324 {
325 	struct vb2_dma_sg_buf *buf = buf_priv;
326 	int err;
327 
328 	if (!buf) {
329 		printk(KERN_ERR "No memory to map\n");
330 		return -EINVAL;
331 	}
332 
333 	err = vm_map_pages(vma, buf->pages, buf->num_pages);
334 	if (err) {
335 		printk(KERN_ERR "Remapping memory, error: %d\n", err);
336 		return err;
337 	}
338 
339 	/*
340 	 * Use common vm_area operations to track buffer refcount.
341 	 */
342 	vma->vm_private_data	= &buf->handler;
343 	vma->vm_ops		= &vb2_common_vm_ops;
344 
345 	vma->vm_ops->open(vma);
346 
347 	return 0;
348 }
349 
350 /*********************************************/
351 /*         DMABUF ops for exporters          */
352 /*********************************************/
353 
354 struct vb2_dma_sg_attachment {
355 	struct sg_table sgt;
356 	enum dma_data_direction dma_dir;
357 };
358 
359 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf,
360 	struct dma_buf_attachment *dbuf_attach)
361 {
362 	struct vb2_dma_sg_attachment *attach;
363 	unsigned int i;
364 	struct scatterlist *rd, *wr;
365 	struct sg_table *sgt;
366 	struct vb2_dma_sg_buf *buf = dbuf->priv;
367 	int ret;
368 
369 	attach = kzalloc(sizeof(*attach), GFP_KERNEL);
370 	if (!attach)
371 		return -ENOMEM;
372 
373 	sgt = &attach->sgt;
374 	/* Copy the buf->base_sgt scatter list to the attachment, as we can't
375 	 * map the same scatter list to multiple attachments at the same time.
376 	 */
377 	ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
378 	if (ret) {
379 		kfree(attach);
380 		return -ENOMEM;
381 	}
382 
383 	rd = buf->dma_sgt->sgl;
384 	wr = sgt->sgl;
385 	for (i = 0; i < sgt->orig_nents; ++i) {
386 		sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
387 		rd = sg_next(rd);
388 		wr = sg_next(wr);
389 	}
390 
391 	attach->dma_dir = DMA_NONE;
392 	dbuf_attach->priv = attach;
393 
394 	return 0;
395 }
396 
397 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
398 	struct dma_buf_attachment *db_attach)
399 {
400 	struct vb2_dma_sg_attachment *attach = db_attach->priv;
401 	struct sg_table *sgt;
402 
403 	if (!attach)
404 		return;
405 
406 	sgt = &attach->sgt;
407 
408 	/* release the scatterlist cache */
409 	if (attach->dma_dir != DMA_NONE)
410 		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, 0);
411 	sg_free_table(sgt);
412 	kfree(attach);
413 	db_attach->priv = NULL;
414 }
415 
416 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
417 	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
418 {
419 	struct vb2_dma_sg_attachment *attach = db_attach->priv;
420 	/* stealing dmabuf mutex to serialize map/unmap operations */
421 	struct mutex *lock = &db_attach->dmabuf->lock;
422 	struct sg_table *sgt;
423 
424 	mutex_lock(lock);
425 
426 	sgt = &attach->sgt;
427 	/* return previously mapped sg table */
428 	if (attach->dma_dir == dma_dir) {
429 		mutex_unlock(lock);
430 		return sgt;
431 	}
432 
433 	/* release any previous cache */
434 	if (attach->dma_dir != DMA_NONE) {
435 		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, 0);
436 		attach->dma_dir = DMA_NONE;
437 	}
438 
439 	/* mapping to the client with new direction */
440 	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
441 		pr_err("failed to map scatterlist\n");
442 		mutex_unlock(lock);
443 		return ERR_PTR(-EIO);
444 	}
445 
446 	attach->dma_dir = dma_dir;
447 
448 	mutex_unlock(lock);
449 
450 	return sgt;
451 }
452 
453 static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
454 	struct sg_table *sgt, enum dma_data_direction dma_dir)
455 {
456 	/* nothing to be done here */
457 }
458 
459 static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
460 {
461 	/* drop reference obtained in vb2_dma_sg_get_dmabuf */
462 	vb2_dma_sg_put(dbuf->priv);
463 }
464 
465 static int
466 vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
467 				       enum dma_data_direction direction)
468 {
469 	struct vb2_dma_sg_buf *buf = dbuf->priv;
470 	struct sg_table *sgt = buf->dma_sgt;
471 
472 	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
473 	return 0;
474 }
475 
476 static int
477 vb2_dma_sg_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf,
478 				     enum dma_data_direction direction)
479 {
480 	struct vb2_dma_sg_buf *buf = dbuf->priv;
481 	struct sg_table *sgt = buf->dma_sgt;
482 
483 	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
484 	return 0;
485 }
486 
487 static int vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf, struct dma_buf_map *map)
488 {
489 	struct vb2_dma_sg_buf *buf = dbuf->priv;
490 
491 	dma_buf_map_set_vaddr(map, buf->vaddr);
492 
493 	return 0;
494 }
495 
496 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
497 	struct vm_area_struct *vma)
498 {
499 	return vb2_dma_sg_mmap(dbuf->priv, vma);
500 }
501 
502 static const struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
503 	.attach = vb2_dma_sg_dmabuf_ops_attach,
504 	.detach = vb2_dma_sg_dmabuf_ops_detach,
505 	.map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
506 	.unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
507 	.begin_cpu_access = vb2_dma_sg_dmabuf_ops_begin_cpu_access,
508 	.end_cpu_access = vb2_dma_sg_dmabuf_ops_end_cpu_access,
509 	.vmap = vb2_dma_sg_dmabuf_ops_vmap,
510 	.mmap = vb2_dma_sg_dmabuf_ops_mmap,
511 	.release = vb2_dma_sg_dmabuf_ops_release,
512 };
513 
514 static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags)
515 {
516 	struct vb2_dma_sg_buf *buf = buf_priv;
517 	struct dma_buf *dbuf;
518 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
519 
520 	exp_info.ops = &vb2_dma_sg_dmabuf_ops;
521 	exp_info.size = buf->size;
522 	exp_info.flags = flags;
523 	exp_info.priv = buf;
524 
525 	if (WARN_ON(!buf->dma_sgt))
526 		return NULL;
527 
528 	dbuf = dma_buf_export(&exp_info);
529 	if (IS_ERR(dbuf))
530 		return NULL;
531 
532 	/* dmabuf keeps reference to vb2 buffer */
533 	refcount_inc(&buf->refcount);
534 
535 	return dbuf;
536 }
537 
538 /*********************************************/
539 /*       callbacks for DMABUF buffers        */
540 /*********************************************/
541 
542 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
543 {
544 	struct vb2_dma_sg_buf *buf = mem_priv;
545 	struct sg_table *sgt;
546 
547 	if (WARN_ON(!buf->db_attach)) {
548 		pr_err("trying to pin a non attached buffer\n");
549 		return -EINVAL;
550 	}
551 
552 	if (WARN_ON(buf->dma_sgt)) {
553 		pr_err("dmabuf buffer is already pinned\n");
554 		return 0;
555 	}
556 
557 	/* get the associated scatterlist for this buffer */
558 	sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
559 	if (IS_ERR(sgt)) {
560 		pr_err("Error getting dmabuf scatterlist\n");
561 		return -EINVAL;
562 	}
563 
564 	buf->dma_sgt = sgt;
565 	buf->vaddr = NULL;
566 
567 	return 0;
568 }
569 
570 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
571 {
572 	struct vb2_dma_sg_buf *buf = mem_priv;
573 	struct sg_table *sgt = buf->dma_sgt;
574 	struct dma_buf_map map = DMA_BUF_MAP_INIT_VADDR(buf->vaddr);
575 
576 	if (WARN_ON(!buf->db_attach)) {
577 		pr_err("trying to unpin a not attached buffer\n");
578 		return;
579 	}
580 
581 	if (WARN_ON(!sgt)) {
582 		pr_err("dmabuf buffer is already unpinned\n");
583 		return;
584 	}
585 
586 	if (buf->vaddr) {
587 		dma_buf_vunmap(buf->db_attach->dmabuf, &map);
588 		buf->vaddr = NULL;
589 	}
590 	dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
591 
592 	buf->dma_sgt = NULL;
593 }
594 
595 static void vb2_dma_sg_detach_dmabuf(void *mem_priv)
596 {
597 	struct vb2_dma_sg_buf *buf = mem_priv;
598 
599 	/* if vb2 works correctly you should never detach mapped buffer */
600 	if (WARN_ON(buf->dma_sgt))
601 		vb2_dma_sg_unmap_dmabuf(buf);
602 
603 	/* detach this attachment */
604 	dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
605 	kfree(buf);
606 }
607 
608 static void *vb2_dma_sg_attach_dmabuf(struct device *dev, struct dma_buf *dbuf,
609 	unsigned long size, enum dma_data_direction dma_dir)
610 {
611 	struct vb2_dma_sg_buf *buf;
612 	struct dma_buf_attachment *dba;
613 
614 	if (WARN_ON(!dev))
615 		return ERR_PTR(-EINVAL);
616 
617 	if (dbuf->size < size)
618 		return ERR_PTR(-EFAULT);
619 
620 	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
621 	if (!buf)
622 		return ERR_PTR(-ENOMEM);
623 
624 	buf->dev = dev;
625 	/* create attachment for the dmabuf with the user device */
626 	dba = dma_buf_attach(dbuf, buf->dev);
627 	if (IS_ERR(dba)) {
628 		pr_err("failed to attach dmabuf\n");
629 		kfree(buf);
630 		return dba;
631 	}
632 
633 	buf->dma_dir = dma_dir;
634 	buf->size = size;
635 	buf->db_attach = dba;
636 
637 	return buf;
638 }
639 
640 static void *vb2_dma_sg_cookie(void *buf_priv)
641 {
642 	struct vb2_dma_sg_buf *buf = buf_priv;
643 
644 	return buf->dma_sgt;
645 }
646 
647 const struct vb2_mem_ops vb2_dma_sg_memops = {
648 	.alloc		= vb2_dma_sg_alloc,
649 	.put		= vb2_dma_sg_put,
650 	.get_userptr	= vb2_dma_sg_get_userptr,
651 	.put_userptr	= vb2_dma_sg_put_userptr,
652 	.prepare	= vb2_dma_sg_prepare,
653 	.finish		= vb2_dma_sg_finish,
654 	.vaddr		= vb2_dma_sg_vaddr,
655 	.mmap		= vb2_dma_sg_mmap,
656 	.num_users	= vb2_dma_sg_num_users,
657 	.get_dmabuf	= vb2_dma_sg_get_dmabuf,
658 	.map_dmabuf	= vb2_dma_sg_map_dmabuf,
659 	.unmap_dmabuf	= vb2_dma_sg_unmap_dmabuf,
660 	.attach_dmabuf	= vb2_dma_sg_attach_dmabuf,
661 	.detach_dmabuf	= vb2_dma_sg_detach_dmabuf,
662 	.cookie		= vb2_dma_sg_cookie,
663 };
664 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
665 
666 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
667 MODULE_AUTHOR("Andrzej Pietrasiewicz");
668 MODULE_LICENSE("GPL");
669