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 	struct vb2_buffer		*vb;
56 };
57 
58 static void vb2_dma_sg_put(void *buf_priv);
59 
vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf * buf,gfp_t gfp_flags)60 static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
61 		gfp_t gfp_flags)
62 {
63 	unsigned int last_page = 0;
64 	unsigned long size = buf->size;
65 
66 	while (size > 0) {
67 		struct page *pages;
68 		int order;
69 		int i;
70 
71 		order = get_order(size);
72 		/* Don't over allocate*/
73 		if ((PAGE_SIZE << order) > size)
74 			order--;
75 
76 		pages = NULL;
77 		while (!pages) {
78 			pages = alloc_pages(GFP_KERNEL | __GFP_ZERO |
79 					__GFP_NOWARN | gfp_flags, order);
80 			if (pages)
81 				break;
82 
83 			if (order == 0) {
84 				while (last_page--)
85 					__free_page(buf->pages[last_page]);
86 				return -ENOMEM;
87 			}
88 			order--;
89 		}
90 
91 		split_page(pages, order);
92 		for (i = 0; i < (1 << order); i++)
93 			buf->pages[last_page++] = &pages[i];
94 
95 		size -= PAGE_SIZE << order;
96 	}
97 
98 	return 0;
99 }
100 
vb2_dma_sg_alloc(struct vb2_buffer * vb,struct device * dev,unsigned long size)101 static void *vb2_dma_sg_alloc(struct vb2_buffer *vb, struct device *dev,
102 			      unsigned long size)
103 {
104 	struct vb2_dma_sg_buf *buf;
105 	struct sg_table *sgt;
106 	int ret;
107 	int num_pages;
108 
109 	if (WARN_ON(!dev) || WARN_ON(!size))
110 		return ERR_PTR(-EINVAL);
111 
112 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
113 	if (!buf)
114 		return ERR_PTR(-ENOMEM);
115 
116 	buf->vaddr = NULL;
117 	buf->dma_dir = vb->vb2_queue->dma_dir;
118 	buf->offset = 0;
119 	buf->size = size;
120 	/* size is already page aligned */
121 	buf->num_pages = size >> PAGE_SHIFT;
122 	buf->dma_sgt = &buf->sg_table;
123 
124 	/*
125 	 * NOTE: dma-sg allocates memory using the page allocator directly, so
126 	 * there is no memory consistency guarantee, hence dma-sg ignores DMA
127 	 * attributes passed from the upper layer.
128 	 */
129 	buf->pages = kvcalloc(buf->num_pages, sizeof(struct page *), GFP_KERNEL);
130 	if (!buf->pages)
131 		goto fail_pages_array_alloc;
132 
133 	ret = vb2_dma_sg_alloc_compacted(buf, vb->vb2_queue->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 	buf->vb = vb;
158 
159 	refcount_set(&buf->refcount, 1);
160 
161 	dprintk(1, "%s: Allocated buffer of %d pages\n",
162 		__func__, buf->num_pages);
163 	return buf;
164 
165 fail_map:
166 	put_device(buf->dev);
167 	sg_free_table(buf->dma_sgt);
168 fail_table_alloc:
169 	num_pages = buf->num_pages;
170 	while (num_pages--)
171 		__free_page(buf->pages[num_pages]);
172 fail_pages_alloc:
173 	kvfree(buf->pages);
174 fail_pages_array_alloc:
175 	kfree(buf);
176 	return ERR_PTR(-ENOMEM);
177 }
178 
vb2_dma_sg_put(void * buf_priv)179 static void vb2_dma_sg_put(void *buf_priv)
180 {
181 	struct vb2_dma_sg_buf *buf = buf_priv;
182 	struct sg_table *sgt = &buf->sg_table;
183 	int i = buf->num_pages;
184 
185 	if (refcount_dec_and_test(&buf->refcount)) {
186 		dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
187 			buf->num_pages);
188 		dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir,
189 				  DMA_ATTR_SKIP_CPU_SYNC);
190 		if (buf->vaddr)
191 			vm_unmap_ram(buf->vaddr, buf->num_pages);
192 		sg_free_table(buf->dma_sgt);
193 		while (--i >= 0)
194 			__free_page(buf->pages[i]);
195 		kvfree(buf->pages);
196 		put_device(buf->dev);
197 		kfree(buf);
198 	}
199 }
200 
vb2_dma_sg_prepare(void * buf_priv)201 static void vb2_dma_sg_prepare(void *buf_priv)
202 {
203 	struct vb2_dma_sg_buf *buf = buf_priv;
204 	struct sg_table *sgt = buf->dma_sgt;
205 
206 	if (buf->vb->skip_cache_sync_on_prepare)
207 		return;
208 
209 	dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
210 }
211 
vb2_dma_sg_finish(void * buf_priv)212 static void vb2_dma_sg_finish(void *buf_priv)
213 {
214 	struct vb2_dma_sg_buf *buf = buf_priv;
215 	struct sg_table *sgt = buf->dma_sgt;
216 
217 	if (buf->vb->skip_cache_sync_on_finish)
218 		return;
219 
220 	dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
221 }
222 
vb2_dma_sg_get_userptr(struct vb2_buffer * vb,struct device * dev,unsigned long vaddr,unsigned long size)223 static void *vb2_dma_sg_get_userptr(struct vb2_buffer *vb, struct device *dev,
224 				    unsigned long vaddr, unsigned long size)
225 {
226 	struct vb2_dma_sg_buf *buf;
227 	struct sg_table *sgt;
228 	struct frame_vector *vec;
229 
230 	if (WARN_ON(!dev))
231 		return ERR_PTR(-EINVAL);
232 
233 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
234 	if (!buf)
235 		return ERR_PTR(-ENOMEM);
236 
237 	buf->vaddr = NULL;
238 	buf->dev = dev;
239 	buf->dma_dir = vb->vb2_queue->dma_dir;
240 	buf->offset = vaddr & ~PAGE_MASK;
241 	buf->size = size;
242 	buf->dma_sgt = &buf->sg_table;
243 	buf->vb = vb;
244 	vec = vb2_create_framevec(vaddr, size);
245 	if (IS_ERR(vec))
246 		goto userptr_fail_pfnvec;
247 	buf->vec = vec;
248 
249 	buf->pages = frame_vector_pages(vec);
250 	if (IS_ERR(buf->pages))
251 		goto userptr_fail_sgtable;
252 	buf->num_pages = frame_vector_count(vec);
253 
254 	if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
255 			buf->num_pages, buf->offset, size, 0))
256 		goto userptr_fail_sgtable;
257 
258 	sgt = &buf->sg_table;
259 	/*
260 	 * No need to sync to the device, this will happen later when the
261 	 * prepare() memop is called.
262 	 */
263 	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
264 			    DMA_ATTR_SKIP_CPU_SYNC))
265 		goto userptr_fail_map;
266 
267 	return buf;
268 
269 userptr_fail_map:
270 	sg_free_table(&buf->sg_table);
271 userptr_fail_sgtable:
272 	vb2_destroy_framevec(vec);
273 userptr_fail_pfnvec:
274 	kfree(buf);
275 	return ERR_PTR(-ENOMEM);
276 }
277 
278 /*
279  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
280  *		 be used
281  */
vb2_dma_sg_put_userptr(void * buf_priv)282 static void vb2_dma_sg_put_userptr(void *buf_priv)
283 {
284 	struct vb2_dma_sg_buf *buf = buf_priv;
285 	struct sg_table *sgt = &buf->sg_table;
286 	int i = buf->num_pages;
287 
288 	dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
289 	       __func__, buf->num_pages);
290 	dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
291 	if (buf->vaddr)
292 		vm_unmap_ram(buf->vaddr, buf->num_pages);
293 	sg_free_table(buf->dma_sgt);
294 	if (buf->dma_dir == DMA_FROM_DEVICE ||
295 	    buf->dma_dir == DMA_BIDIRECTIONAL)
296 		while (--i >= 0)
297 			set_page_dirty_lock(buf->pages[i]);
298 	vb2_destroy_framevec(buf->vec);
299 	kfree(buf);
300 }
301 
vb2_dma_sg_vaddr(struct vb2_buffer * vb,void * buf_priv)302 static void *vb2_dma_sg_vaddr(struct vb2_buffer *vb, void *buf_priv)
303 {
304 	struct vb2_dma_sg_buf *buf = buf_priv;
305 	struct iosys_map map;
306 	int ret;
307 
308 	BUG_ON(!buf);
309 
310 	if (!buf->vaddr) {
311 		if (buf->db_attach) {
312 			ret = dma_buf_vmap(buf->db_attach->dmabuf, &map);
313 			buf->vaddr = ret ? NULL : map.vaddr;
314 		} else {
315 			buf->vaddr = vm_map_ram(buf->pages, buf->num_pages, -1);
316 		}
317 	}
318 
319 	/* add offset in case userptr is not page-aligned */
320 	return buf->vaddr ? buf->vaddr + buf->offset : NULL;
321 }
322 
vb2_dma_sg_num_users(void * buf_priv)323 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
324 {
325 	struct vb2_dma_sg_buf *buf = buf_priv;
326 
327 	return refcount_read(&buf->refcount);
328 }
329 
vb2_dma_sg_mmap(void * buf_priv,struct vm_area_struct * vma)330 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
331 {
332 	struct vb2_dma_sg_buf *buf = buf_priv;
333 	int err;
334 
335 	if (!buf) {
336 		printk(KERN_ERR "No memory to map\n");
337 		return -EINVAL;
338 	}
339 
340 	err = vm_map_pages(vma, buf->pages, buf->num_pages);
341 	if (err) {
342 		printk(KERN_ERR "Remapping memory, error: %d\n", err);
343 		return err;
344 	}
345 
346 	/*
347 	 * Use common vm_area operations to track buffer refcount.
348 	 */
349 	vma->vm_private_data	= &buf->handler;
350 	vma->vm_ops		= &vb2_common_vm_ops;
351 
352 	vma->vm_ops->open(vma);
353 
354 	return 0;
355 }
356 
357 /*********************************************/
358 /*         DMABUF ops for exporters          */
359 /*********************************************/
360 
361 struct vb2_dma_sg_attachment {
362 	struct sg_table sgt;
363 	enum dma_data_direction dma_dir;
364 };
365 
vb2_dma_sg_dmabuf_ops_attach(struct dma_buf * dbuf,struct dma_buf_attachment * dbuf_attach)366 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf,
367 	struct dma_buf_attachment *dbuf_attach)
368 {
369 	struct vb2_dma_sg_attachment *attach;
370 	unsigned int i;
371 	struct scatterlist *rd, *wr;
372 	struct sg_table *sgt;
373 	struct vb2_dma_sg_buf *buf = dbuf->priv;
374 	int ret;
375 
376 	attach = kzalloc(sizeof(*attach), GFP_KERNEL);
377 	if (!attach)
378 		return -ENOMEM;
379 
380 	sgt = &attach->sgt;
381 	/* Copy the buf->base_sgt scatter list to the attachment, as we can't
382 	 * map the same scatter list to multiple attachments at the same time.
383 	 */
384 	ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
385 	if (ret) {
386 		kfree(attach);
387 		return -ENOMEM;
388 	}
389 
390 	rd = buf->dma_sgt->sgl;
391 	wr = sgt->sgl;
392 	for (i = 0; i < sgt->orig_nents; ++i) {
393 		sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
394 		rd = sg_next(rd);
395 		wr = sg_next(wr);
396 	}
397 
398 	attach->dma_dir = DMA_NONE;
399 	dbuf_attach->priv = attach;
400 
401 	return 0;
402 }
403 
vb2_dma_sg_dmabuf_ops_detach(struct dma_buf * dbuf,struct dma_buf_attachment * db_attach)404 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
405 	struct dma_buf_attachment *db_attach)
406 {
407 	struct vb2_dma_sg_attachment *attach = db_attach->priv;
408 	struct sg_table *sgt;
409 
410 	if (!attach)
411 		return;
412 
413 	sgt = &attach->sgt;
414 
415 	/* release the scatterlist cache */
416 	if (attach->dma_dir != DMA_NONE)
417 		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, 0);
418 	sg_free_table(sgt);
419 	kfree(attach);
420 	db_attach->priv = NULL;
421 }
422 
vb2_dma_sg_dmabuf_ops_map(struct dma_buf_attachment * db_attach,enum dma_data_direction dma_dir)423 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
424 	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
425 {
426 	struct vb2_dma_sg_attachment *attach = db_attach->priv;
427 	/* stealing dmabuf mutex to serialize map/unmap operations */
428 	struct mutex *lock = &db_attach->dmabuf->lock;
429 	struct sg_table *sgt;
430 
431 	mutex_lock(lock);
432 
433 	sgt = &attach->sgt;
434 	/* return previously mapped sg table */
435 	if (attach->dma_dir == dma_dir) {
436 		mutex_unlock(lock);
437 		return sgt;
438 	}
439 
440 	/* release any previous cache */
441 	if (attach->dma_dir != DMA_NONE) {
442 		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, 0);
443 		attach->dma_dir = DMA_NONE;
444 	}
445 
446 	/* mapping to the client with new direction */
447 	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
448 		pr_err("failed to map scatterlist\n");
449 		mutex_unlock(lock);
450 		return ERR_PTR(-EIO);
451 	}
452 
453 	attach->dma_dir = dma_dir;
454 
455 	mutex_unlock(lock);
456 
457 	return sgt;
458 }
459 
vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment * db_attach,struct sg_table * sgt,enum dma_data_direction dma_dir)460 static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
461 	struct sg_table *sgt, enum dma_data_direction dma_dir)
462 {
463 	/* nothing to be done here */
464 }
465 
vb2_dma_sg_dmabuf_ops_release(struct dma_buf * dbuf)466 static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
467 {
468 	/* drop reference obtained in vb2_dma_sg_get_dmabuf */
469 	vb2_dma_sg_put(dbuf->priv);
470 }
471 
472 static int
vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf * dbuf,enum dma_data_direction direction)473 vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
474 				       enum dma_data_direction direction)
475 {
476 	struct vb2_dma_sg_buf *buf = dbuf->priv;
477 	struct sg_table *sgt = buf->dma_sgt;
478 
479 	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
480 	return 0;
481 }
482 
483 static int
vb2_dma_sg_dmabuf_ops_end_cpu_access(struct dma_buf * dbuf,enum dma_data_direction direction)484 vb2_dma_sg_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf,
485 				     enum dma_data_direction direction)
486 {
487 	struct vb2_dma_sg_buf *buf = dbuf->priv;
488 	struct sg_table *sgt = buf->dma_sgt;
489 
490 	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
491 	return 0;
492 }
493 
vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf * dbuf,struct iosys_map * map)494 static int vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf,
495 				      struct iosys_map *map)
496 {
497 	struct vb2_dma_sg_buf *buf = dbuf->priv;
498 
499 	iosys_map_set_vaddr(map, buf->vaddr);
500 
501 	return 0;
502 }
503 
vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf * dbuf,struct vm_area_struct * vma)504 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
505 	struct vm_area_struct *vma)
506 {
507 	return vb2_dma_sg_mmap(dbuf->priv, vma);
508 }
509 
510 static const struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
511 	.attach = vb2_dma_sg_dmabuf_ops_attach,
512 	.detach = vb2_dma_sg_dmabuf_ops_detach,
513 	.map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
514 	.unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
515 	.begin_cpu_access = vb2_dma_sg_dmabuf_ops_begin_cpu_access,
516 	.end_cpu_access = vb2_dma_sg_dmabuf_ops_end_cpu_access,
517 	.vmap = vb2_dma_sg_dmabuf_ops_vmap,
518 	.mmap = vb2_dma_sg_dmabuf_ops_mmap,
519 	.release = vb2_dma_sg_dmabuf_ops_release,
520 };
521 
vb2_dma_sg_get_dmabuf(struct vb2_buffer * vb,void * buf_priv,unsigned long flags)522 static struct dma_buf *vb2_dma_sg_get_dmabuf(struct vb2_buffer *vb,
523 					     void *buf_priv,
524 					     unsigned long flags)
525 {
526 	struct vb2_dma_sg_buf *buf = buf_priv;
527 	struct dma_buf *dbuf;
528 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
529 
530 	exp_info.ops = &vb2_dma_sg_dmabuf_ops;
531 	exp_info.size = buf->size;
532 	exp_info.flags = flags;
533 	exp_info.priv = buf;
534 
535 	if (WARN_ON(!buf->dma_sgt))
536 		return NULL;
537 
538 	dbuf = dma_buf_export(&exp_info);
539 	if (IS_ERR(dbuf))
540 		return NULL;
541 
542 	/* dmabuf keeps reference to vb2 buffer */
543 	refcount_inc(&buf->refcount);
544 
545 	return dbuf;
546 }
547 
548 /*********************************************/
549 /*       callbacks for DMABUF buffers        */
550 /*********************************************/
551 
vb2_dma_sg_map_dmabuf(void * mem_priv)552 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
553 {
554 	struct vb2_dma_sg_buf *buf = mem_priv;
555 	struct sg_table *sgt;
556 
557 	if (WARN_ON(!buf->db_attach)) {
558 		pr_err("trying to pin a non attached buffer\n");
559 		return -EINVAL;
560 	}
561 
562 	if (WARN_ON(buf->dma_sgt)) {
563 		pr_err("dmabuf buffer is already pinned\n");
564 		return 0;
565 	}
566 
567 	/* get the associated scatterlist for this buffer */
568 	sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
569 	if (IS_ERR(sgt)) {
570 		pr_err("Error getting dmabuf scatterlist\n");
571 		return -EINVAL;
572 	}
573 
574 	buf->dma_sgt = sgt;
575 	buf->vaddr = NULL;
576 
577 	return 0;
578 }
579 
vb2_dma_sg_unmap_dmabuf(void * mem_priv)580 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
581 {
582 	struct vb2_dma_sg_buf *buf = mem_priv;
583 	struct sg_table *sgt = buf->dma_sgt;
584 	struct iosys_map map = IOSYS_MAP_INIT_VADDR(buf->vaddr);
585 
586 	if (WARN_ON(!buf->db_attach)) {
587 		pr_err("trying to unpin a not attached buffer\n");
588 		return;
589 	}
590 
591 	if (WARN_ON(!sgt)) {
592 		pr_err("dmabuf buffer is already unpinned\n");
593 		return;
594 	}
595 
596 	if (buf->vaddr) {
597 		dma_buf_vunmap(buf->db_attach->dmabuf, &map);
598 		buf->vaddr = NULL;
599 	}
600 	dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
601 
602 	buf->dma_sgt = NULL;
603 }
604 
vb2_dma_sg_detach_dmabuf(void * mem_priv)605 static void vb2_dma_sg_detach_dmabuf(void *mem_priv)
606 {
607 	struct vb2_dma_sg_buf *buf = mem_priv;
608 
609 	/* if vb2 works correctly you should never detach mapped buffer */
610 	if (WARN_ON(buf->dma_sgt))
611 		vb2_dma_sg_unmap_dmabuf(buf);
612 
613 	/* detach this attachment */
614 	dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
615 	kfree(buf);
616 }
617 
vb2_dma_sg_attach_dmabuf(struct vb2_buffer * vb,struct device * dev,struct dma_buf * dbuf,unsigned long size)618 static void *vb2_dma_sg_attach_dmabuf(struct vb2_buffer *vb, struct device *dev,
619 				      struct dma_buf *dbuf, unsigned long size)
620 {
621 	struct vb2_dma_sg_buf *buf;
622 	struct dma_buf_attachment *dba;
623 
624 	if (WARN_ON(!dev))
625 		return ERR_PTR(-EINVAL);
626 
627 	if (dbuf->size < size)
628 		return ERR_PTR(-EFAULT);
629 
630 	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
631 	if (!buf)
632 		return ERR_PTR(-ENOMEM);
633 
634 	buf->dev = dev;
635 	/* create attachment for the dmabuf with the user device */
636 	dba = dma_buf_attach(dbuf, buf->dev);
637 	if (IS_ERR(dba)) {
638 		pr_err("failed to attach dmabuf\n");
639 		kfree(buf);
640 		return dba;
641 	}
642 
643 	buf->dma_dir = vb->vb2_queue->dma_dir;
644 	buf->size = size;
645 	buf->db_attach = dba;
646 	buf->vb = vb;
647 
648 	return buf;
649 }
650 
vb2_dma_sg_cookie(struct vb2_buffer * vb,void * buf_priv)651 static void *vb2_dma_sg_cookie(struct vb2_buffer *vb, void *buf_priv)
652 {
653 	struct vb2_dma_sg_buf *buf = buf_priv;
654 
655 	return buf->dma_sgt;
656 }
657 
658 const struct vb2_mem_ops vb2_dma_sg_memops = {
659 	.alloc		= vb2_dma_sg_alloc,
660 	.put		= vb2_dma_sg_put,
661 	.get_userptr	= vb2_dma_sg_get_userptr,
662 	.put_userptr	= vb2_dma_sg_put_userptr,
663 	.prepare	= vb2_dma_sg_prepare,
664 	.finish		= vb2_dma_sg_finish,
665 	.vaddr		= vb2_dma_sg_vaddr,
666 	.mmap		= vb2_dma_sg_mmap,
667 	.num_users	= vb2_dma_sg_num_users,
668 	.get_dmabuf	= vb2_dma_sg_get_dmabuf,
669 	.map_dmabuf	= vb2_dma_sg_map_dmabuf,
670 	.unmap_dmabuf	= vb2_dma_sg_unmap_dmabuf,
671 	.attach_dmabuf	= vb2_dma_sg_attach_dmabuf,
672 	.detach_dmabuf	= vb2_dma_sg_detach_dmabuf,
673 	.cookie		= vb2_dma_sg_cookie,
674 };
675 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
676 
677 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
678 MODULE_AUTHOR("Andrzej Pietrasiewicz");
679 MODULE_LICENSE("GPL");
680 MODULE_IMPORT_NS(DMA_BUF);
681