drivers/media/v4l2-core/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 <andrzej.p@samsung.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/scatterlist.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/vmalloc.h>
  19
  20 #include <media/videobuf2-v4l2.h>
  21 #include <media/videobuf2-memops.h>
  22 #include <media/videobuf2-dma-sg.h>
  23
  24 static int debug;
  25 module_param(debug, int, 0644);
  26
  27 #define dprintk(level, fmt, arg...)                                     \
  28         do {                                                            \
  29                 if (debug >= level)                                     \
  30                         printk(KERN_DEBUG "vb2-dma-sg: " fmt, ## arg);  \
  31         } while (0)
  32
  33 struct vb2_dma_sg_conf {
  34         struct device           *dev;
  35 };
  36
  37 struct vb2_dma_sg_buf {
  38         struct device                   *dev;
  39         void                            *vaddr;
  40         struct page                     **pages;
  41         struct frame_vector             *vec;
  42         int                             offset;
  43         enum dma_data_direction         dma_dir;
  44         struct sg_table                 sg_table;
  45         /*
  46          * This will point to sg_table when used with the MMAP or USERPTR
  47          * memory model, and to the dma_buf sglist when used with the
  48          * DMABUF memory model.
  49          */
  50         struct sg_table                 *dma_sgt;
  51         size_t                          size;
  52         unsigned int                    num_pages;
  53         atomic_t                        refcount;
  54         struct vb2_vmarea_handler       handler;
  55
  56         struct dma_buf_attachment       *db_attach;
  57 };
  58
  59 static void vb2_dma_sg_put(void *buf_priv);
  60
  61 static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
  62                 gfp_t gfp_flags)
  63 {
  64         unsigned int last_page = 0;
  65         int size = buf->size;
  66
  67         while (size > 0) {
  68                 struct page *pages;
  69                 int order;
  70                 int i;
  71
  72                 order = get_order(size);
  73                 /* Dont over allocate*/
  74                 if ((PAGE_SIZE << order) > size)
  75                         order--;
  76
  77                 pages = NULL;
  78                 while (!pages) {
  79                         pages = alloc_pages(GFP_KERNEL | __GFP_ZERO |
  80                                         __GFP_NOWARN | gfp_flags, order);
  81                         if (pages)
  82                                 break;
  83
  84                         if (order == 0) {
  85                                 while (last_page--)
  86                                         __free_page(buf->pages[last_page]);
  87                                 return -ENOMEM;
  88                         }
  89                         order--;
  90                 }
  91
  92                 split_page(pages, order);
  93                 for (i = 0; i < (1 << order); i++)
  94                         buf->pages[last_page++] = &pages[i];
  95
  96                 size -= PAGE_SIZE << order;
  97         }
  98
  99         return 0;
 100 }
 101
 102 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size,
 103                               enum dma_data_direction dma_dir, gfp_t gfp_flags)
 104 {
 105         struct vb2_dma_sg_conf *conf = alloc_ctx;
 106         struct vb2_dma_sg_buf *buf;
 107         struct sg_table *sgt;
 108         int ret;
 109         int num_pages;
 110         DEFINE_DMA_ATTRS(attrs);
 111
 112         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 113
 114         if (WARN_ON(alloc_ctx == NULL))
 115                 return NULL;
 116         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 117         if (!buf)
 118                 return NULL;
 119
 120         buf->vaddr = NULL;
 121         buf->dma_dir = dma_dir;
 122         buf->offset = 0;
 123         buf->size = size;
 124         /* size is already page aligned */
 125         buf->num_pages = size >> PAGE_SHIFT;
 126         buf->dma_sgt = &buf->sg_table;
 127
 128         buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
 129                              GFP_KERNEL);
 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(conf->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         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 151                                       buf->dma_dir, &attrs);
 152         if (!sgt->nents)
 153                 goto fail_map;
 154
 155         buf->handler.refcount = &buf->refcount;
 156         buf->handler.put = vb2_dma_sg_put;
 157         buf->handler.arg = buf;
 158
 159         atomic_inc(&buf->refcount);
 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         kfree(buf->pages);
 174 fail_pages_array_alloc:
 175         kfree(buf);
 176         return NULL;
 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 (atomic_dec_and_test(&buf->refcount)) {
 186                 DEFINE_DMA_ATTRS(attrs);
 187
 188                 dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 189                 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
 190                         buf->num_pages);
 191                 dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 192                                    buf->dma_dir, &attrs);
 193                 if (buf->vaddr)
 194                         vm_unmap_ram(buf->vaddr, buf->num_pages);
 195                 sg_free_table(buf->dma_sgt);
 196                 while (--i >= 0)
 197                         __free_page(buf->pages[i]);
 198                 kfree(buf->pages);
 199                 put_device(buf->dev);
 200                 kfree(buf);
 201         }
 202 }
 203
 204 static void vb2_dma_sg_prepare(void *buf_priv)
 205 {
 206         struct vb2_dma_sg_buf *buf = buf_priv;
 207         struct sg_table *sgt = buf->dma_sgt;
 208
 209         /* DMABUF exporter will flush the cache for us */
 210         if (buf->db_attach)
 211                 return;
 212
 213         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
 214                                buf->dma_dir);
 215 }
 216
 217 static void vb2_dma_sg_finish(void *buf_priv)
 218 {
 219         struct vb2_dma_sg_buf *buf = buf_priv;
 220         struct sg_table *sgt = buf->dma_sgt;
 221
 222         /* DMABUF exporter will flush the cache for us */
 223         if (buf->db_attach)
 224                 return;
 225
 226         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 227 }
 228
 229 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 230                                     unsigned long size,
 231                                     enum dma_data_direction dma_dir)
 232 {
 233         struct vb2_dma_sg_conf *conf = alloc_ctx;
 234         struct vb2_dma_sg_buf *buf;
 235         struct sg_table *sgt;
 236         DEFINE_DMA_ATTRS(attrs);
 237         struct frame_vector *vec;
 238
 239         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 240         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 241         if (!buf)
 242                 return NULL;
 243
 244         buf->vaddr = NULL;
 245         buf->dev = conf->dev;
 246         buf->dma_dir = dma_dir;
 247         buf->offset = vaddr & ~PAGE_MASK;
 248         buf->size = size;
 249         buf->dma_sgt = &buf->sg_table;
 250         vec = vb2_create_framevec(vaddr, size, buf->dma_dir == DMA_FROM_DEVICE);
 251         if (IS_ERR(vec))
 252                 goto userptr_fail_pfnvec;
 253         buf->vec = vec;
 254
 255         buf->pages = frame_vector_pages(vec);
 256         if (IS_ERR(buf->pages))
 257                 goto userptr_fail_sgtable;
 258         buf->num_pages = frame_vector_count(vec);
 259
 260         if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 261                         buf->num_pages, buf->offset, size, 0))
 262                 goto userptr_fail_sgtable;
 263
 264         sgt = &buf->sg_table;
 265         /*
 266          * No need to sync to the device, this will happen later when the
 267          * prepare() memop is called.
 268          */
 269         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 270                                       buf->dma_dir, &attrs);
 271         if (!sgt->nents)
 272                 goto userptr_fail_map;
 273
 274         return buf;
 275
 276 userptr_fail_map:
 277         sg_free_table(&buf->sg_table);
 278 userptr_fail_sgtable:
 279         vb2_destroy_framevec(vec);
 280 userptr_fail_pfnvec:
 281         kfree(buf);
 282         return NULL;
 283 }
 284
 285 /*
 286  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 287  *               be used
 288  */
 289 static void vb2_dma_sg_put_userptr(void *buf_priv)
 290 {
 291         struct vb2_dma_sg_buf *buf = buf_priv;
 292         struct sg_table *sgt = &buf->sg_table;
 293         int i = buf->num_pages;
 294         DEFINE_DMA_ATTRS(attrs);
 295
 296         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 297
 298         dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
 299                __func__, buf->num_pages);
 300         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir,
 301                            &attrs);
 302         if (buf->vaddr)
 303                 vm_unmap_ram(buf->vaddr, buf->num_pages);
 304         sg_free_table(buf->dma_sgt);
 305         while (--i >= 0) {
 306                 if (buf->dma_dir == DMA_FROM_DEVICE)
 307                         set_page_dirty_lock(buf->pages[i]);
 308         }
 309         vb2_destroy_framevec(buf->vec);
 310         kfree(buf);
 311 }
 312
 313 static void *vb2_dma_sg_vaddr(void *buf_priv)
 314 {
 315         struct vb2_dma_sg_buf *buf = buf_priv;
 316
 317         BUG_ON(!buf);
 318
 319         if (!buf->vaddr) {
 320                 if (buf->db_attach)
 321                         buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
 322                 else
 323                         buf->vaddr = vm_map_ram(buf->pages,
 324                                         buf->num_pages, -1, PAGE_KERNEL);
 325         }
 326
 327         /* add offset in case userptr is not page-aligned */
 328         return buf->vaddr ? buf->vaddr + buf->offset : NULL;
 329 }
 330
 331 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
 332 {
 333         struct vb2_dma_sg_buf *buf = buf_priv;
 334
 335         return atomic_read(&buf->refcount);
 336 }
 337
 338 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
 339 {
 340         struct vb2_dma_sg_buf *buf = buf_priv;
 341         unsigned long uaddr = vma->vm_start;
 342         unsigned long usize = vma->vm_end - vma->vm_start;
 343         int i = 0;
 344
 345         if (!buf) {
 346                 printk(KERN_ERR "No memory to map\n");
 347                 return -EINVAL;
 348         }
 349
 350         do {
 351                 int ret;
 352
 353                 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
 354                 if (ret) {
 355                         printk(KERN_ERR "Remapping memory, error: %d\n", ret);
 356                         return ret;
 357                 }
 358
 359                 uaddr += PAGE_SIZE;
 360                 usize -= PAGE_SIZE;
 361         } while (usize > 0);
 362
 363
 364         /*
 365          * Use common vm_area operations to track buffer refcount.
 366          */
 367         vma->vm_private_data    = &buf->handler;
 368         vma->vm_ops             = &vb2_common_vm_ops;
 369
 370         vma->vm_ops->open(vma);
 371
 372         return 0;
 373 }
 374
 375 /*********************************************/
 376 /*         DMABUF ops for exporters          */
 377 /*********************************************/
 378
 379 struct vb2_dma_sg_attachment {
 380         struct sg_table sgt;
 381         enum dma_data_direction dma_dir;
 382 };
 383
 384 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 385         struct dma_buf_attachment *dbuf_attach)
 386 {
 387         struct vb2_dma_sg_attachment *attach;
 388         unsigned int i;
 389         struct scatterlist *rd, *wr;
 390         struct sg_table *sgt;
 391         struct vb2_dma_sg_buf *buf = dbuf->priv;
 392         int ret;
 393
 394         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 395         if (!attach)
 396                 return -ENOMEM;
 397
 398         sgt = &attach->sgt;
 399         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 400          * map the same scatter list to multiple attachments at the same time.
 401          */
 402         ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
 403         if (ret) {
 404                 kfree(attach);
 405                 return -ENOMEM;
 406         }
 407
 408         rd = buf->dma_sgt->sgl;
 409         wr = sgt->sgl;
 410         for (i = 0; i < sgt->orig_nents; ++i) {
 411                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 412                 rd = sg_next(rd);
 413                 wr = sg_next(wr);
 414         }
 415
 416         attach->dma_dir = DMA_NONE;
 417         dbuf_attach->priv = attach;
 418
 419         return 0;
 420 }
 421
 422 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
 423         struct dma_buf_attachment *db_attach)
 424 {
 425         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 426         struct sg_table *sgt;
 427
 428         if (!attach)
 429                 return;
 430
 431         sgt = &attach->sgt;
 432
 433         /* release the scatterlist cache */
 434         if (attach->dma_dir != DMA_NONE)
 435                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 436                         attach->dma_dir);
 437         sg_free_table(sgt);
 438         kfree(attach);
 439         db_attach->priv = NULL;
 440 }
 441
 442 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 443         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 444 {
 445         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 446         /* stealing dmabuf mutex to serialize map/unmap operations */
 447         struct mutex *lock = &db_attach->dmabuf->lock;
 448         struct sg_table *sgt;
 449
 450         mutex_lock(lock);
 451
 452         sgt = &attach->sgt;
 453         /* return previously mapped sg table */
 454         if (attach->dma_dir == dma_dir) {
 455                 mutex_unlock(lock);
 456                 return sgt;
 457         }
 458
 459         /* release any previous cache */
 460         if (attach->dma_dir != DMA_NONE) {
 461                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 462                         attach->dma_dir);
 463                 attach->dma_dir = DMA_NONE;
 464         }
 465
 466         /* mapping to the client with new direction */
 467         sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 468                                 dma_dir);
 469         if (!sgt->nents) {
 470                 pr_err("failed to map scatterlist\n");
 471                 mutex_unlock(lock);
 472                 return ERR_PTR(-EIO);
 473         }
 474
 475         attach->dma_dir = dma_dir;
 476
 477         mutex_unlock(lock);
 478
 479         return sgt;
 480 }
 481
 482 static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 483         struct sg_table *sgt, enum dma_data_direction dma_dir)
 484 {
 485         /* nothing to be done here */
 486 }
 487
 488 static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
 489 {
 490         /* drop reference obtained in vb2_dma_sg_get_dmabuf */
 491         vb2_dma_sg_put(dbuf->priv);
 492 }
 493
 494 static void *vb2_dma_sg_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 495 {
 496         struct vb2_dma_sg_buf *buf = dbuf->priv;
 497
 498         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 499 }
 500
 501 static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
 502 {
 503         struct vb2_dma_sg_buf *buf = dbuf->priv;
 504
 505         return vb2_dma_sg_vaddr(buf);
 506 }
 507
 508 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
 509         struct vm_area_struct *vma)
 510 {
 511         return vb2_dma_sg_mmap(dbuf->priv, vma);
 512 }
 513
 514 static struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 515         .attach = vb2_dma_sg_dmabuf_ops_attach,
 516         .detach = vb2_dma_sg_dmabuf_ops_detach,
 517         .map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 518         .unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
 519         .kmap = vb2_dma_sg_dmabuf_ops_kmap,
 520         .kmap_atomic = vb2_dma_sg_dmabuf_ops_kmap,
 521         .vmap = vb2_dma_sg_dmabuf_ops_vmap,
 522         .mmap = vb2_dma_sg_dmabuf_ops_mmap,
 523         .release = vb2_dma_sg_dmabuf_ops_release,
 524 };
 525
 526 static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags)
 527 {
 528         struct vb2_dma_sg_buf *buf = buf_priv;
 529         struct dma_buf *dbuf;
 530         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 531
 532         exp_info.ops = &vb2_dma_sg_dmabuf_ops;
 533         exp_info.size = buf->size;
 534         exp_info.flags = flags;
 535         exp_info.priv = buf;
 536
 537         if (WARN_ON(!buf->dma_sgt))
 538                 return NULL;
 539
 540         dbuf = dma_buf_export(&exp_info);
 541         if (IS_ERR(dbuf))
 542                 return NULL;
 543
 544         /* dmabuf keeps reference to vb2 buffer */
 545         atomic_inc(&buf->refcount);
 546
 547         return dbuf;
 548 }
 549
 550 /*********************************************/
 551 /*       callbacks for DMABUF buffers        */
 552 /*********************************************/
 553
 554 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
 555 {
 556         struct vb2_dma_sg_buf *buf = mem_priv;
 557         struct sg_table *sgt;
 558
 559         if (WARN_ON(!buf->db_attach)) {
 560                 pr_err("trying to pin a non attached buffer\n");
 561                 return -EINVAL;
 562         }
 563
 564         if (WARN_ON(buf->dma_sgt)) {
 565                 pr_err("dmabuf buffer is already pinned\n");
 566                 return 0;
 567         }
 568
 569         /* get the associated scatterlist for this buffer */
 570         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 571         if (IS_ERR(sgt)) {
 572                 pr_err("Error getting dmabuf scatterlist\n");
 573                 return -EINVAL;
 574         }
 575
 576         buf->dma_sgt = sgt;
 577         buf->vaddr = NULL;
 578
 579         return 0;
 580 }
 581
 582 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
 583 {
 584         struct vb2_dma_sg_buf *buf = mem_priv;
 585         struct sg_table *sgt = buf->dma_sgt;
 586
 587         if (WARN_ON(!buf->db_attach)) {
 588                 pr_err("trying to unpin a not attached buffer\n");
 589                 return;
 590         }
 591
 592         if (WARN_ON(!sgt)) {
 593                 pr_err("dmabuf buffer is already unpinned\n");
 594                 return;
 595         }
 596
 597         if (buf->vaddr) {
 598                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 599                 buf->vaddr = NULL;
 600         }
 601         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 602
 603         buf->dma_sgt = NULL;
 604 }
 605
 606 static void vb2_dma_sg_detach_dmabuf(void *mem_priv)
 607 {
 608         struct vb2_dma_sg_buf *buf = mem_priv;
 609
 610         /* if vb2 works correctly you should never detach mapped buffer */
 611         if (WARN_ON(buf->dma_sgt))
 612                 vb2_dma_sg_unmap_dmabuf(buf);
 613
 614         /* detach this attachment */
 615         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 616         kfree(buf);
 617 }
 618
 619 static void *vb2_dma_sg_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 620         unsigned long size, enum dma_data_direction dma_dir)
 621 {
 622         struct vb2_dma_sg_conf *conf = alloc_ctx;
 623         struct vb2_dma_sg_buf *buf;
 624         struct dma_buf_attachment *dba;
 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 = conf->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 = dma_dir;
 643         buf->size = size;
 644         buf->db_attach = dba;
 645
 646         return buf;
 647 }
 648
 649 static void *vb2_dma_sg_cookie(void *buf_priv)
 650 {
 651         struct vb2_dma_sg_buf *buf = buf_priv;
 652
 653         return buf->dma_sgt;
 654 }
 655
 656 const struct vb2_mem_ops vb2_dma_sg_memops = {
 657         .alloc          = vb2_dma_sg_alloc,
 658         .put            = vb2_dma_sg_put,
 659         .get_userptr    = vb2_dma_sg_get_userptr,
 660         .put_userptr    = vb2_dma_sg_put_userptr,
 661         .prepare        = vb2_dma_sg_prepare,
 662         .finish         = vb2_dma_sg_finish,
 663         .vaddr          = vb2_dma_sg_vaddr,
 664         .mmap           = vb2_dma_sg_mmap,
 665         .num_users      = vb2_dma_sg_num_users,
 666         .get_dmabuf     = vb2_dma_sg_get_dmabuf,
 667         .map_dmabuf     = vb2_dma_sg_map_dmabuf,
 668         .unmap_dmabuf   = vb2_dma_sg_unmap_dmabuf,
 669         .attach_dmabuf  = vb2_dma_sg_attach_dmabuf,
 670         .detach_dmabuf  = vb2_dma_sg_detach_dmabuf,
 671         .cookie         = vb2_dma_sg_cookie,
 672 };
 673 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
 674
 675 void *vb2_dma_sg_init_ctx(struct device *dev)
 676 {
 677         struct vb2_dma_sg_conf *conf;
 678
 679         conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 680         if (!conf)
 681                 return ERR_PTR(-ENOMEM);
 682
 683         conf->dev = dev;
 684
 685         return conf;
 686 }
 687 EXPORT_SYMBOL_GPL(vb2_dma_sg_init_ctx);
 688
 689 void vb2_dma_sg_cleanup_ctx(void *alloc_ctx)
 690 {
 691         if (!IS_ERR_OR_NULL(alloc_ctx))
 692                 kfree(alloc_ctx);
 693 }
 694 EXPORT_SYMBOL_GPL(vb2_dma_sg_cleanup_ctx);
 695
 696 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
 697 MODULE_AUTHOR("Andrzej Pietrasiewicz");
 698 MODULE_LICENSE("GPL");