drivers/media/common/videobuf2/videobuf2-dma-sg.c

   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         buf->pages = kvmalloc_array(buf->num_pages, sizeof(struct page *),
 124                                     GFP_KERNEL | __GFP_ZERO);
 125         if (!buf->pages)
 126                 goto fail_pages_array_alloc;
 127
 128         ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags);
 129         if (ret)
 130                 goto fail_pages_alloc;
 131
 132         ret = sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 133                         buf->num_pages, 0, size, GFP_KERNEL);
 134         if (ret)
 135                 goto fail_table_alloc;
 136
 137         /* Prevent the device from being released while the buffer is used */
 138         buf->dev = get_device(dev);
 139
 140         sgt = &buf->sg_table;
 141         /*
 142          * No need to sync to the device, this will happen later when the
 143          * prepare() memop is called.
 144          */
 145         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 146                                       buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 147         if (!sgt->nents)
 148                 goto fail_map;
 149
 150         buf->handler.refcount = &buf->refcount;
 151         buf->handler.put = vb2_dma_sg_put;
 152         buf->handler.arg = buf;
 153
 154         refcount_set(&buf->refcount, 1);
 155
 156         dprintk(1, "%s: Allocated buffer of %d pages\n",
 157                 __func__, buf->num_pages);
 158         return buf;
 159
 160 fail_map:
 161         put_device(buf->dev);
 162         sg_free_table(buf->dma_sgt);
 163 fail_table_alloc:
 164         num_pages = buf->num_pages;
 165         while (num_pages--)
 166                 __free_page(buf->pages[num_pages]);
 167 fail_pages_alloc:
 168         kvfree(buf->pages);
 169 fail_pages_array_alloc:
 170         kfree(buf);
 171         return ERR_PTR(-ENOMEM);
 172 }
 173
 174 static void vb2_dma_sg_put(void *buf_priv)
 175 {
 176         struct vb2_dma_sg_buf *buf = buf_priv;
 177         struct sg_table *sgt = &buf->sg_table;
 178         int i = buf->num_pages;
 179
 180         if (refcount_dec_and_test(&buf->refcount)) {
 181                 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
 182                         buf->num_pages);
 183                 dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 184                                    buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 185                 if (buf->vaddr)
 186                         vm_unmap_ram(buf->vaddr, buf->num_pages);
 187                 sg_free_table(buf->dma_sgt);
 188                 while (--i >= 0)
 189                         __free_page(buf->pages[i]);
 190                 kvfree(buf->pages);
 191                 put_device(buf->dev);
 192                 kfree(buf);
 193         }
 194 }
 195
 196 static void vb2_dma_sg_prepare(void *buf_priv)
 197 {
 198         struct vb2_dma_sg_buf *buf = buf_priv;
 199         struct sg_table *sgt = buf->dma_sgt;
 200
 201         /* DMABUF exporter will flush the cache for us */
 202         if (buf->db_attach)
 203                 return;
 204
 205         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
 206                                buf->dma_dir);
 207 }
 208
 209 static void vb2_dma_sg_finish(void *buf_priv)
 210 {
 211         struct vb2_dma_sg_buf *buf = buf_priv;
 212         struct sg_table *sgt = buf->dma_sgt;
 213
 214         /* DMABUF exporter will flush the cache for us */
 215         if (buf->db_attach)
 216                 return;
 217
 218         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 219 }
 220
 221 static void *vb2_dma_sg_get_userptr(struct device *dev, unsigned long vaddr,
 222                                     unsigned long size,
 223                                     enum dma_data_direction dma_dir)
 224 {
 225         struct vb2_dma_sg_buf *buf;
 226         struct sg_table *sgt;
 227         struct frame_vector *vec;
 228
 229         if (WARN_ON(!dev))
 230                 return ERR_PTR(-EINVAL);
 231
 232         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 233         if (!buf)
 234                 return ERR_PTR(-ENOMEM);
 235
 236         buf->vaddr = NULL;
 237         buf->dev = dev;
 238         buf->dma_dir = dma_dir;
 239         buf->offset = vaddr & ~PAGE_MASK;
 240         buf->size = size;
 241         buf->dma_sgt = &buf->sg_table;
 242         vec = vb2_create_framevec(vaddr, size);
 243         if (IS_ERR(vec))
 244                 goto userptr_fail_pfnvec;
 245         buf->vec = vec;
 246
 247         buf->pages = frame_vector_pages(vec);
 248         if (IS_ERR(buf->pages))
 249                 goto userptr_fail_sgtable;
 250         buf->num_pages = frame_vector_count(vec);
 251
 252         if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 253                         buf->num_pages, buf->offset, size, 0))
 254                 goto userptr_fail_sgtable;
 255
 256         sgt = &buf->sg_table;
 257         /*
 258          * No need to sync to the device, this will happen later when the
 259          * prepare() memop is called.
 260          */
 261         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 262                                       buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 263         if (!sgt->nents)
 264                 goto userptr_fail_map;
 265
 266         return buf;
 267
 268 userptr_fail_map:
 269         sg_free_table(&buf->sg_table);
 270 userptr_fail_sgtable:
 271         vb2_destroy_framevec(vec);
 272 userptr_fail_pfnvec:
 273         kfree(buf);
 274         return ERR_PTR(-ENOMEM);
 275 }
 276
 277 /*
 278  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 279  *               be used
 280  */
 281 static void vb2_dma_sg_put_userptr(void *buf_priv)
 282 {
 283         struct vb2_dma_sg_buf *buf = buf_priv;
 284         struct sg_table *sgt = &buf->sg_table;
 285         int i = buf->num_pages;
 286
 287         dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
 288                __func__, buf->num_pages);
 289         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir,
 290                            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
 302 static void *vb2_dma_sg_vaddr(void *buf_priv)
 303 {
 304         struct vb2_dma_sg_buf *buf = buf_priv;
 305
 306         BUG_ON(!buf);
 307
 308         if (!buf->vaddr) {
 309                 if (buf->db_attach)
 310                         buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
 311                 else
 312                         buf->vaddr = vm_map_ram(buf->pages,
 313                                         buf->num_pages, -1, PAGE_KERNEL);
 314         }
 315
 316         /* add offset in case userptr is not page-aligned */
 317         return buf->vaddr ? buf->vaddr + buf->offset : NULL;
 318 }
 319
 320 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
 321 {
 322         struct vb2_dma_sg_buf *buf = buf_priv;
 323
 324         return refcount_read(&buf->refcount);
 325 }
 326
 327 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
 328 {
 329         struct vb2_dma_sg_buf *buf = buf_priv;
 330         int err;
 331
 332         if (!buf) {
 333                 printk(KERN_ERR "No memory to map\n");
 334                 return -EINVAL;
 335         }
 336
 337         err = vm_map_pages(vma, buf->pages, buf->num_pages);
 338         if (err) {
 339                 printk(KERN_ERR "Remapping memory, error: %d\n", err);
 340                 return err;
 341         }
 342
 343         /*
 344          * Use common vm_area operations to track buffer refcount.
 345          */
 346         vma->vm_private_data    = &buf->handler;
 347         vma->vm_ops             = &vb2_common_vm_ops;
 348
 349         vma->vm_ops->open(vma);
 350
 351         return 0;
 352 }
 353
 354 /*********************************************/
 355 /*         DMABUF ops for exporters          */
 356 /*********************************************/
 357
 358 struct vb2_dma_sg_attachment {
 359         struct sg_table sgt;
 360         enum dma_data_direction dma_dir;
 361 };
 362
 363 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf,
 364         struct dma_buf_attachment *dbuf_attach)
 365 {
 366         struct vb2_dma_sg_attachment *attach;
 367         unsigned int i;
 368         struct scatterlist *rd, *wr;
 369         struct sg_table *sgt;
 370         struct vb2_dma_sg_buf *buf = dbuf->priv;
 371         int ret;
 372
 373         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 374         if (!attach)
 375                 return -ENOMEM;
 376
 377         sgt = &attach->sgt;
 378         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 379          * map the same scatter list to multiple attachments at the same time.
 380          */
 381         ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
 382         if (ret) {
 383                 kfree(attach);
 384                 return -ENOMEM;
 385         }
 386
 387         rd = buf->dma_sgt->sgl;
 388         wr = sgt->sgl;
 389         for (i = 0; i < sgt->orig_nents; ++i) {
 390                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 391                 rd = sg_next(rd);
 392                 wr = sg_next(wr);
 393         }
 394
 395         attach->dma_dir = DMA_NONE;
 396         dbuf_attach->priv = attach;
 397
 398         return 0;
 399 }
 400
 401 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
 402         struct dma_buf_attachment *db_attach)
 403 {
 404         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 405         struct sg_table *sgt;
 406
 407         if (!attach)
 408                 return;
 409
 410         sgt = &attach->sgt;
 411
 412         /* release the scatterlist cache */
 413         if (attach->dma_dir != DMA_NONE)
 414                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 415                         attach->dma_dir);
 416         sg_free_table(sgt);
 417         kfree(attach);
 418         db_attach->priv = NULL;
 419 }
 420
 421 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 422         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 423 {
 424         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 425         /* stealing dmabuf mutex to serialize map/unmap operations */
 426         struct mutex *lock = &db_attach->dmabuf->lock;
 427         struct sg_table *sgt;
 428
 429         mutex_lock(lock);
 430
 431         sgt = &attach->sgt;
 432         /* return previously mapped sg table */
 433         if (attach->dma_dir == dma_dir) {
 434                 mutex_unlock(lock);
 435                 return sgt;
 436         }
 437
 438         /* release any previous cache */
 439         if (attach->dma_dir != DMA_NONE) {
 440                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 441                         attach->dma_dir);
 442                 attach->dma_dir = DMA_NONE;
 443         }
 444
 445         /* mapping to the client with new direction */
 446         sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 447                                 dma_dir);
 448         if (!sgt->nents) {
 449                 pr_err("failed to map scatterlist\n");
 450                 mutex_unlock(lock);
 451                 return ERR_PTR(-EIO);
 452         }
 453
 454         attach->dma_dir = dma_dir;
 455
 456         mutex_unlock(lock);
 457
 458         return sgt;
 459 }
 460
 461 static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 462         struct sg_table *sgt, enum dma_data_direction dma_dir)
 463 {
 464         /* nothing to be done here */
 465 }
 466
 467 static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
 468 {
 469         /* drop reference obtained in vb2_dma_sg_get_dmabuf */
 470         vb2_dma_sg_put(dbuf->priv);
 471 }
 472
 473 static void *vb2_dma_sg_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 474 {
 475         struct vb2_dma_sg_buf *buf = dbuf->priv;
 476
 477         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 478 }
 479
 480 static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
 481 {
 482         struct vb2_dma_sg_buf *buf = dbuf->priv;
 483
 484         return vb2_dma_sg_vaddr(buf);
 485 }
 486
 487 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
 488         struct vm_area_struct *vma)
 489 {
 490         return vb2_dma_sg_mmap(dbuf->priv, vma);
 491 }
 492
 493 static const struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 494         .attach = vb2_dma_sg_dmabuf_ops_attach,
 495         .detach = vb2_dma_sg_dmabuf_ops_detach,
 496         .map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 497         .unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
 498         .map = vb2_dma_sg_dmabuf_ops_kmap,
 499         .vmap = vb2_dma_sg_dmabuf_ops_vmap,
 500         .mmap = vb2_dma_sg_dmabuf_ops_mmap,
 501         .release = vb2_dma_sg_dmabuf_ops_release,
 502 };
 503
 504 static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags)
 505 {
 506         struct vb2_dma_sg_buf *buf = buf_priv;
 507         struct dma_buf *dbuf;
 508         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 509
 510         exp_info.ops = &vb2_dma_sg_dmabuf_ops;
 511         exp_info.size = buf->size;
 512         exp_info.flags = flags;
 513         exp_info.priv = buf;
 514
 515         if (WARN_ON(!buf->dma_sgt))
 516                 return NULL;
 517
 518         dbuf = dma_buf_export(&exp_info);
 519         if (IS_ERR(dbuf))
 520                 return NULL;
 521
 522         /* dmabuf keeps reference to vb2 buffer */
 523         refcount_inc(&buf->refcount);
 524
 525         return dbuf;
 526 }
 527
 528 /*********************************************/
 529 /*       callbacks for DMABUF buffers        */
 530 /*********************************************/
 531
 532 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
 533 {
 534         struct vb2_dma_sg_buf *buf = mem_priv;
 535         struct sg_table *sgt;
 536
 537         if (WARN_ON(!buf->db_attach)) {
 538                 pr_err("trying to pin a non attached buffer\n");
 539                 return -EINVAL;
 540         }
 541
 542         if (WARN_ON(buf->dma_sgt)) {
 543                 pr_err("dmabuf buffer is already pinned\n");
 544                 return 0;
 545         }
 546
 547         /* get the associated scatterlist for this buffer */
 548         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 549         if (IS_ERR(sgt)) {
 550                 pr_err("Error getting dmabuf scatterlist\n");
 551                 return -EINVAL;
 552         }
 553
 554         buf->dma_sgt = sgt;
 555         buf->vaddr = NULL;
 556
 557         return 0;
 558 }
 559
 560 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
 561 {
 562         struct vb2_dma_sg_buf *buf = mem_priv;
 563         struct sg_table *sgt = buf->dma_sgt;
 564
 565         if (WARN_ON(!buf->db_attach)) {
 566                 pr_err("trying to unpin a not attached buffer\n");
 567                 return;
 568         }
 569
 570         if (WARN_ON(!sgt)) {
 571                 pr_err("dmabuf buffer is already unpinned\n");
 572                 return;
 573         }
 574
 575         if (buf->vaddr) {
 576                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 577                 buf->vaddr = NULL;
 578         }
 579         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 580
 581         buf->dma_sgt = NULL;
 582 }
 583
 584 static void vb2_dma_sg_detach_dmabuf(void *mem_priv)
 585 {
 586         struct vb2_dma_sg_buf *buf = mem_priv;
 587
 588         /* if vb2 works correctly you should never detach mapped buffer */
 589         if (WARN_ON(buf->dma_sgt))
 590                 vb2_dma_sg_unmap_dmabuf(buf);
 591
 592         /* detach this attachment */
 593         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 594         kfree(buf);
 595 }
 596
 597 static void *vb2_dma_sg_attach_dmabuf(struct device *dev, struct dma_buf *dbuf,
 598         unsigned long size, enum dma_data_direction dma_dir)
 599 {
 600         struct vb2_dma_sg_buf *buf;
 601         struct dma_buf_attachment *dba;
 602
 603         if (WARN_ON(!dev))
 604                 return ERR_PTR(-EINVAL);
 605
 606         if (dbuf->size < size)
 607                 return ERR_PTR(-EFAULT);
 608
 609         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 610         if (!buf)
 611                 return ERR_PTR(-ENOMEM);
 612
 613         buf->dev = dev;
 614         /* create attachment for the dmabuf with the user device */
 615         dba = dma_buf_attach(dbuf, buf->dev);
 616         if (IS_ERR(dba)) {
 617                 pr_err("failed to attach dmabuf\n");
 618                 kfree(buf);
 619                 return dba;
 620         }
 621
 622         buf->dma_dir = dma_dir;
 623         buf->size = size;
 624         buf->db_attach = dba;
 625
 626         return buf;
 627 }
 628
 629 static void *vb2_dma_sg_cookie(void *buf_priv)
 630 {
 631         struct vb2_dma_sg_buf *buf = buf_priv;
 632
 633         return buf->dma_sgt;
 634 }
 635
 636 const struct vb2_mem_ops vb2_dma_sg_memops = {
 637         .alloc          = vb2_dma_sg_alloc,
 638         .put            = vb2_dma_sg_put,
 639         .get_userptr    = vb2_dma_sg_get_userptr,
 640         .put_userptr    = vb2_dma_sg_put_userptr,
 641         .prepare        = vb2_dma_sg_prepare,
 642         .finish         = vb2_dma_sg_finish,
 643         .vaddr          = vb2_dma_sg_vaddr,
 644         .mmap           = vb2_dma_sg_mmap,
 645         .num_users      = vb2_dma_sg_num_users,
 646         .get_dmabuf     = vb2_dma_sg_get_dmabuf,
 647         .map_dmabuf     = vb2_dma_sg_map_dmabuf,
 648         .unmap_dmabuf   = vb2_dma_sg_unmap_dmabuf,
 649         .attach_dmabuf  = vb2_dma_sg_attach_dmabuf,
 650         .detach_dmabuf  = vb2_dma_sg_detach_dmabuf,
 651         .cookie         = vb2_dma_sg_cookie,
 652 };
 653 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
 654
 655 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
 656 MODULE_AUTHOR("Andrzej Pietrasiewicz");
 657 MODULE_LICENSE("GPL");