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         struct vb2_buffer               *vb;
  56 };
  57
  58 static void vb2_dma_sg_put(void *buf_priv);
  59
  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
 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
 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
 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
 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
 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                                   buf->dma_dir == DMA_FROM_DEVICE ||
 246                                   buf->dma_dir == DMA_BIDIRECTIONAL);
 247         if (IS_ERR(vec))
 248                 goto userptr_fail_pfnvec;
 249         buf->vec = vec;
 250
 251         buf->pages = frame_vector_pages(vec);
 252         if (IS_ERR(buf->pages))
 253                 goto userptr_fail_sgtable;
 254         buf->num_pages = frame_vector_count(vec);
 255
 256         if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 257                         buf->num_pages, buf->offset, size, 0))
 258                 goto userptr_fail_sgtable;
 259
 260         sgt = &buf->sg_table;
 261         /*
 262          * No need to sync to the device, this will happen later when the
 263          * prepare() memop is called.
 264          */
 265         if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
 266                             DMA_ATTR_SKIP_CPU_SYNC))
 267                 goto userptr_fail_map;
 268
 269         return buf;
 270
 271 userptr_fail_map:
 272         sg_free_table(&buf->sg_table);
 273 userptr_fail_sgtable:
 274         vb2_destroy_framevec(vec);
 275 userptr_fail_pfnvec:
 276         kfree(buf);
 277         return ERR_PTR(-ENOMEM);
 278 }
 279
 280 /*
 281  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 282  *               be used
 283  */
 284 static void vb2_dma_sg_put_userptr(void *buf_priv)
 285 {
 286         struct vb2_dma_sg_buf *buf = buf_priv;
 287         struct sg_table *sgt = &buf->sg_table;
 288         int i = buf->num_pages;
 289
 290         dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
 291                __func__, buf->num_pages);
 292         dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 293         if (buf->vaddr)
 294                 vm_unmap_ram(buf->vaddr, buf->num_pages);
 295         sg_free_table(buf->dma_sgt);
 296         if (buf->dma_dir == DMA_FROM_DEVICE ||
 297             buf->dma_dir == DMA_BIDIRECTIONAL)
 298                 while (--i >= 0)
 299                         set_page_dirty_lock(buf->pages[i]);
 300         vb2_destroy_framevec(buf->vec);
 301         kfree(buf);
 302 }
 303
 304 static void *vb2_dma_sg_vaddr(struct vb2_buffer *vb, void *buf_priv)
 305 {
 306         struct vb2_dma_sg_buf *buf = buf_priv;
 307         struct iosys_map map;
 308         int ret;
 309
 310         BUG_ON(!buf);
 311
 312         if (!buf->vaddr) {
 313                 if (buf->db_attach) {
 314                         ret = dma_buf_vmap_unlocked(buf->db_attach->dmabuf, &map);
 315                         buf->vaddr = ret ? NULL : map.vaddr;
 316                 } else {
 317                         buf->vaddr = vm_map_ram(buf->pages, buf->num_pages, -1);
 318                 }
 319         }
 320
 321         /* add offset in case userptr is not page-aligned */
 322         return buf->vaddr ? buf->vaddr + buf->offset : NULL;
 323 }
 324
 325 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
 326 {
 327         struct vb2_dma_sg_buf *buf = buf_priv;
 328
 329         return refcount_read(&buf->refcount);
 330 }
 331
 332 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
 333 {
 334         struct vb2_dma_sg_buf *buf = buf_priv;
 335         int err;
 336
 337         if (!buf) {
 338                 printk(KERN_ERR "No memory to map\n");
 339                 return -EINVAL;
 340         }
 341
 342         err = vm_map_pages(vma, buf->pages, buf->num_pages);
 343         if (err) {
 344                 printk(KERN_ERR "Remapping memory, error: %d\n", err);
 345                 return err;
 346         }
 347
 348         /*
 349          * Use common vm_area operations to track buffer refcount.
 350          */
 351         vma->vm_private_data    = &buf->handler;
 352         vma->vm_ops             = &vb2_common_vm_ops;
 353
 354         vma->vm_ops->open(vma);
 355
 356         return 0;
 357 }
 358
 359 /*********************************************/
 360 /*         DMABUF ops for exporters          */
 361 /*********************************************/
 362
 363 struct vb2_dma_sg_attachment {
 364         struct sg_table sgt;
 365         enum dma_data_direction dma_dir;
 366 };
 367
 368 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf,
 369         struct dma_buf_attachment *dbuf_attach)
 370 {
 371         struct vb2_dma_sg_attachment *attach;
 372         unsigned int i;
 373         struct scatterlist *rd, *wr;
 374         struct sg_table *sgt;
 375         struct vb2_dma_sg_buf *buf = dbuf->priv;
 376         int ret;
 377
 378         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 379         if (!attach)
 380                 return -ENOMEM;
 381
 382         sgt = &attach->sgt;
 383         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 384          * map the same scatter list to multiple attachments at the same time.
 385          */
 386         ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
 387         if (ret) {
 388                 kfree(attach);
 389                 return -ENOMEM;
 390         }
 391
 392         rd = buf->dma_sgt->sgl;
 393         wr = sgt->sgl;
 394         for (i = 0; i < sgt->orig_nents; ++i) {
 395                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 396                 rd = sg_next(rd);
 397                 wr = sg_next(wr);
 398         }
 399
 400         attach->dma_dir = DMA_NONE;
 401         dbuf_attach->priv = attach;
 402
 403         return 0;
 404 }
 405
 406 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
 407         struct dma_buf_attachment *db_attach)
 408 {
 409         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 410         struct sg_table *sgt;
 411
 412         if (!attach)
 413                 return;
 414
 415         sgt = &attach->sgt;
 416
 417         /* release the scatterlist cache */
 418         if (attach->dma_dir != DMA_NONE)
 419                 dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, 0);
 420         sg_free_table(sgt);
 421         kfree(attach);
 422         db_attach->priv = NULL;
 423 }
 424
 425 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 426         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 427 {
 428         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 429         struct sg_table *sgt;
 430
 431         sgt = &attach->sgt;
 432         /* return previously mapped sg table */
 433         if (attach->dma_dir == dma_dir)
 434                 return sgt;
 435
 436         /* release any previous cache */
 437         if (attach->dma_dir != DMA_NONE) {
 438                 dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, 0);
 439                 attach->dma_dir = DMA_NONE;
 440         }
 441
 442         /* mapping to the client with new direction */
 443         if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, 0)) {
 444                 pr_err("failed to map scatterlist\n");
 445                 return ERR_PTR(-EIO);
 446         }
 447
 448         attach->dma_dir = dma_dir;
 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,
 488                                       struct iosys_map *map)
 489 {
 490         struct vb2_dma_sg_buf *buf;
 491         void *vaddr;
 492
 493         buf = dbuf->priv;
 494         vaddr = vb2_dma_sg_vaddr(buf->vb, buf);
 495         if (!vaddr)
 496                 return -EINVAL;
 497
 498         iosys_map_set_vaddr(map, vaddr);
 499
 500         return 0;
 501 }
 502
 503 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
 504         struct vm_area_struct *vma)
 505 {
 506         return vb2_dma_sg_mmap(dbuf->priv, vma);
 507 }
 508
 509 static const struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 510         .attach = vb2_dma_sg_dmabuf_ops_attach,
 511         .detach = vb2_dma_sg_dmabuf_ops_detach,
 512         .map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 513         .unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
 514         .begin_cpu_access = vb2_dma_sg_dmabuf_ops_begin_cpu_access,
 515         .end_cpu_access = vb2_dma_sg_dmabuf_ops_end_cpu_access,
 516         .vmap = vb2_dma_sg_dmabuf_ops_vmap,
 517         .mmap = vb2_dma_sg_dmabuf_ops_mmap,
 518         .release = vb2_dma_sg_dmabuf_ops_release,
 519 };
 520
 521 static struct dma_buf *vb2_dma_sg_get_dmabuf(struct vb2_buffer *vb,
 522                                              void *buf_priv,
 523                                              unsigned long flags)
 524 {
 525         struct vb2_dma_sg_buf *buf = buf_priv;
 526         struct dma_buf *dbuf;
 527         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 528
 529         exp_info.ops = &vb2_dma_sg_dmabuf_ops;
 530         exp_info.size = buf->size;
 531         exp_info.flags = flags;
 532         exp_info.priv = buf;
 533
 534         if (WARN_ON(!buf->dma_sgt))
 535                 return NULL;
 536
 537         dbuf = dma_buf_export(&exp_info);
 538         if (IS_ERR(dbuf))
 539                 return NULL;
 540
 541         /* dmabuf keeps reference to vb2 buffer */
 542         refcount_inc(&buf->refcount);
 543
 544         return dbuf;
 545 }
 546
 547 /*********************************************/
 548 /*       callbacks for DMABUF buffers        */
 549 /*********************************************/
 550
 551 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
 552 {
 553         struct vb2_dma_sg_buf *buf = mem_priv;
 554         struct sg_table *sgt;
 555
 556         if (WARN_ON(!buf->db_attach)) {
 557                 pr_err("trying to pin a non attached buffer\n");
 558                 return -EINVAL;
 559         }
 560
 561         if (WARN_ON(buf->dma_sgt)) {
 562                 pr_err("dmabuf buffer is already pinned\n");
 563                 return 0;
 564         }
 565
 566         /* get the associated scatterlist for this buffer */
 567         sgt = dma_buf_map_attachment_unlocked(buf->db_attach, buf->dma_dir);
 568         if (IS_ERR(sgt)) {
 569                 pr_err("Error getting dmabuf scatterlist\n");
 570                 return -EINVAL;
 571         }
 572
 573         buf->dma_sgt = sgt;
 574         buf->vaddr = NULL;
 575
 576         return 0;
 577 }
 578
 579 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
 580 {
 581         struct vb2_dma_sg_buf *buf = mem_priv;
 582         struct sg_table *sgt = buf->dma_sgt;
 583         struct iosys_map map = IOSYS_MAP_INIT_VADDR(buf->vaddr);
 584
 585         if (WARN_ON(!buf->db_attach)) {
 586                 pr_err("trying to unpin a not attached buffer\n");
 587                 return;
 588         }
 589
 590         if (WARN_ON(!sgt)) {
 591                 pr_err("dmabuf buffer is already unpinned\n");
 592                 return;
 593         }
 594
 595         if (buf->vaddr) {
 596                 dma_buf_vunmap_unlocked(buf->db_attach->dmabuf, &map);
 597                 buf->vaddr = NULL;
 598         }
 599         dma_buf_unmap_attachment_unlocked(buf->db_attach, sgt, buf->dma_dir);
 600
 601         buf->dma_sgt = NULL;
 602 }
 603
 604 static void vb2_dma_sg_detach_dmabuf(void *mem_priv)
 605 {
 606         struct vb2_dma_sg_buf *buf = mem_priv;
 607
 608         /* if vb2 works correctly you should never detach mapped buffer */
 609         if (WARN_ON(buf->dma_sgt))
 610                 vb2_dma_sg_unmap_dmabuf(buf);
 611
 612         /* detach this attachment */
 613         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 614         kfree(buf);
 615 }
 616
 617 static void *vb2_dma_sg_attach_dmabuf(struct vb2_buffer *vb, struct device *dev,
 618                                       struct dma_buf *dbuf, unsigned long size)
 619 {
 620         struct vb2_dma_sg_buf *buf;
 621         struct dma_buf_attachment *dba;
 622
 623         if (WARN_ON(!dev))
 624                 return ERR_PTR(-EINVAL);
 625
 626         if (dbuf->size < size)
 627                 return ERR_PTR(-EFAULT);
 628
 629         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 630         if (!buf)
 631                 return ERR_PTR(-ENOMEM);
 632
 633         buf->dev = dev;
 634         /* create attachment for the dmabuf with the user device */
 635         dba = dma_buf_attach(dbuf, buf->dev);
 636         if (IS_ERR(dba)) {
 637                 pr_err("failed to attach dmabuf\n");
 638                 kfree(buf);
 639                 return dba;
 640         }
 641
 642         buf->dma_dir = vb->vb2_queue->dma_dir;
 643         buf->size = size;
 644         buf->db_attach = dba;
 645         buf->vb = vb;
 646
 647         return buf;
 648 }
 649
 650 static void *vb2_dma_sg_cookie(struct vb2_buffer *vb, void *buf_priv)
 651 {
 652         struct vb2_dma_sg_buf *buf = buf_priv;
 653
 654         return buf->dma_sgt;
 655 }
 656
 657 const struct vb2_mem_ops vb2_dma_sg_memops = {
 658         .alloc          = vb2_dma_sg_alloc,
 659         .put            = vb2_dma_sg_put,
 660         .get_userptr    = vb2_dma_sg_get_userptr,
 661         .put_userptr    = vb2_dma_sg_put_userptr,
 662         .prepare        = vb2_dma_sg_prepare,
 663         .finish         = vb2_dma_sg_finish,
 664         .vaddr          = vb2_dma_sg_vaddr,
 665         .mmap           = vb2_dma_sg_mmap,
 666         .num_users      = vb2_dma_sg_num_users,
 667         .get_dmabuf     = vb2_dma_sg_get_dmabuf,
 668         .map_dmabuf     = vb2_dma_sg_map_dmabuf,
 669         .unmap_dmabuf   = vb2_dma_sg_unmap_dmabuf,
 670         .attach_dmabuf  = vb2_dma_sg_attach_dmabuf,
 671         .detach_dmabuf  = vb2_dma_sg_detach_dmabuf,
 672         .cookie         = vb2_dma_sg_cookie,
 673 };
 674 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
 675
 676 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
 677 MODULE_AUTHOR("Andrzej Pietrasiewicz");
 678 MODULE_LICENSE("GPL");
 679 MODULE_IMPORT_NS("DMA_BUF");