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-core.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->nents, buf->dma_dir);
 214 }
 215
 216 static void vb2_dma_sg_finish(void *buf_priv)
 217 {
 218         struct vb2_dma_sg_buf *buf = buf_priv;
 219         struct sg_table *sgt = buf->dma_sgt;
 220
 221         /* DMABUF exporter will flush the cache for us */
 222         if (buf->db_attach)
 223                 return;
 224
 225         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 226 }
 227
 228 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 229                                     unsigned long size,
 230                                     enum dma_data_direction dma_dir)
 231 {
 232         struct vb2_dma_sg_conf *conf = alloc_ctx;
 233         struct vb2_dma_sg_buf *buf;
 234         struct sg_table *sgt;
 235         DEFINE_DMA_ATTRS(attrs);
 236         struct frame_vector *vec;
 237
 238         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 239         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 240         if (!buf)
 241                 return NULL;
 242
 243         buf->vaddr = NULL;
 244         buf->dev = conf->dev;
 245         buf->dma_dir = dma_dir;
 246         buf->offset = vaddr & ~PAGE_MASK;
 247         buf->size = size;
 248         buf->dma_sgt = &buf->sg_table;
 249         vec = vb2_create_framevec(vaddr, size, buf->dma_dir == DMA_FROM_DEVICE);
 250         if (IS_ERR(vec))
 251                 goto userptr_fail_pfnvec;
 252         buf->vec = vec;
 253
 254         buf->pages = frame_vector_pages(vec);
 255         if (IS_ERR(buf->pages))
 256                 goto userptr_fail_sgtable;
 257         buf->num_pages = frame_vector_count(vec);
 258
 259         if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 260                         buf->num_pages, buf->offset, size, 0))
 261                 goto userptr_fail_sgtable;
 262
 263         sgt = &buf->sg_table;
 264         /*
 265          * No need to sync to the device, this will happen later when the
 266          * prepare() memop is called.
 267          */
 268         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 269                                       buf->dma_dir, &attrs);
 270         if (!sgt->nents)
 271                 goto userptr_fail_map;
 272
 273         return buf;
 274
 275 userptr_fail_map:
 276         sg_free_table(&buf->sg_table);
 277 userptr_fail_sgtable:
 278         vb2_destroy_framevec(vec);
 279 userptr_fail_pfnvec:
 280         kfree(buf);
 281         return NULL;
 282 }
 283
 284 /*
 285  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 286  *               be used
 287  */
 288 static void vb2_dma_sg_put_userptr(void *buf_priv)
 289 {
 290         struct vb2_dma_sg_buf *buf = buf_priv;
 291         struct sg_table *sgt = &buf->sg_table;
 292         int i = buf->num_pages;
 293         DEFINE_DMA_ATTRS(attrs);
 294
 295         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 296
 297         dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
 298                __func__, buf->num_pages);
 299         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir,
 300                            &attrs);
 301         if (buf->vaddr)
 302                 vm_unmap_ram(buf->vaddr, buf->num_pages);
 303         sg_free_table(buf->dma_sgt);
 304         while (--i >= 0) {
 305                 if (buf->dma_dir == DMA_FROM_DEVICE)
 306                         set_page_dirty_lock(buf->pages[i]);
 307         }
 308         vb2_destroy_framevec(buf->vec);
 309         kfree(buf);
 310 }
 311
 312 static void *vb2_dma_sg_vaddr(void *buf_priv)
 313 {
 314         struct vb2_dma_sg_buf *buf = buf_priv;
 315
 316         BUG_ON(!buf);
 317
 318         if (!buf->vaddr) {
 319                 if (buf->db_attach)
 320                         buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
 321                 else
 322                         buf->vaddr = vm_map_ram(buf->pages,
 323                                         buf->num_pages, -1, PAGE_KERNEL);
 324         }
 325
 326         /* add offset in case userptr is not page-aligned */
 327         return buf->vaddr ? buf->vaddr + buf->offset : NULL;
 328 }
 329
 330 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
 331 {
 332         struct vb2_dma_sg_buf *buf = buf_priv;
 333
 334         return atomic_read(&buf->refcount);
 335 }
 336
 337 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
 338 {
 339         struct vb2_dma_sg_buf *buf = buf_priv;
 340         unsigned long uaddr = vma->vm_start;
 341         unsigned long usize = vma->vm_end - vma->vm_start;
 342         int i = 0;
 343
 344         if (!buf) {
 345                 printk(KERN_ERR "No memory to map\n");
 346                 return -EINVAL;
 347         }
 348
 349         do {
 350                 int ret;
 351
 352                 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
 353                 if (ret) {
 354                         printk(KERN_ERR "Remapping memory, error: %d\n", ret);
 355                         return ret;
 356                 }
 357
 358                 uaddr += PAGE_SIZE;
 359                 usize -= PAGE_SIZE;
 360         } while (usize > 0);
 361
 362
 363         /*
 364          * Use common vm_area operations to track buffer refcount.
 365          */
 366         vma->vm_private_data    = &buf->handler;
 367         vma->vm_ops             = &vb2_common_vm_ops;
 368
 369         vma->vm_ops->open(vma);
 370
 371         return 0;
 372 }
 373
 374 /*********************************************/
 375 /*         DMABUF ops for exporters          */
 376 /*********************************************/
 377
 378 struct vb2_dma_sg_attachment {
 379         struct sg_table sgt;
 380         enum dma_data_direction dma_dir;
 381 };
 382
 383 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 384         struct dma_buf_attachment *dbuf_attach)
 385 {
 386         struct vb2_dma_sg_attachment *attach;
 387         unsigned int i;
 388         struct scatterlist *rd, *wr;
 389         struct sg_table *sgt;
 390         struct vb2_dma_sg_buf *buf = dbuf->priv;
 391         int ret;
 392
 393         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 394         if (!attach)
 395                 return -ENOMEM;
 396
 397         sgt = &attach->sgt;
 398         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 399          * map the same scatter list to multiple attachments at the same time.
 400          */
 401         ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
 402         if (ret) {
 403                 kfree(attach);
 404                 return -ENOMEM;
 405         }
 406
 407         rd = buf->dma_sgt->sgl;
 408         wr = sgt->sgl;
 409         for (i = 0; i < sgt->orig_nents; ++i) {
 410                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 411                 rd = sg_next(rd);
 412                 wr = sg_next(wr);
 413         }
 414
 415         attach->dma_dir = DMA_NONE;
 416         dbuf_attach->priv = attach;
 417
 418         return 0;
 419 }
 420
 421 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
 422         struct dma_buf_attachment *db_attach)
 423 {
 424         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 425         struct sg_table *sgt;
 426
 427         if (!attach)
 428                 return;
 429
 430         sgt = &attach->sgt;
 431
 432         /* release the scatterlist cache */
 433         if (attach->dma_dir != DMA_NONE)
 434                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 435                         attach->dma_dir);
 436         sg_free_table(sgt);
 437         kfree(attach);
 438         db_attach->priv = NULL;
 439 }
 440
 441 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 442         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 443 {
 444         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 445         /* stealing dmabuf mutex to serialize map/unmap operations */
 446         struct mutex *lock = &db_attach->dmabuf->lock;
 447         struct sg_table *sgt;
 448
 449         mutex_lock(lock);
 450
 451         sgt = &attach->sgt;
 452         /* return previously mapped sg table */
 453         if (attach->dma_dir == dma_dir) {
 454                 mutex_unlock(lock);
 455                 return sgt;
 456         }
 457
 458         /* release any previous cache */
 459         if (attach->dma_dir != DMA_NONE) {
 460                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 461                         attach->dma_dir);
 462                 attach->dma_dir = DMA_NONE;
 463         }
 464
 465         /* mapping to the client with new direction */
 466         sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 467                                 dma_dir);
 468         if (!sgt->nents) {
 469                 pr_err("failed to map scatterlist\n");
 470                 mutex_unlock(lock);
 471                 return ERR_PTR(-EIO);
 472         }
 473
 474         attach->dma_dir = dma_dir;
 475
 476         mutex_unlock(lock);
 477
 478         return sgt;
 479 }
 480
 481 static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 482         struct sg_table *sgt, enum dma_data_direction dma_dir)
 483 {
 484         /* nothing to be done here */
 485 }
 486
 487 static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
 488 {
 489         /* drop reference obtained in vb2_dma_sg_get_dmabuf */
 490         vb2_dma_sg_put(dbuf->priv);
 491 }
 492
 493 static void *vb2_dma_sg_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 494 {
 495         struct vb2_dma_sg_buf *buf = dbuf->priv;
 496
 497         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 498 }
 499
 500 static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
 501 {
 502         struct vb2_dma_sg_buf *buf = dbuf->priv;
 503
 504         return vb2_dma_sg_vaddr(buf);
 505 }
 506
 507 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
 508         struct vm_area_struct *vma)
 509 {
 510         return vb2_dma_sg_mmap(dbuf->priv, vma);
 511 }
 512
 513 static struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 514         .attach = vb2_dma_sg_dmabuf_ops_attach,
 515         .detach = vb2_dma_sg_dmabuf_ops_detach,
 516         .map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 517         .unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
 518         .kmap = vb2_dma_sg_dmabuf_ops_kmap,
 519         .kmap_atomic = vb2_dma_sg_dmabuf_ops_kmap,
 520         .vmap = vb2_dma_sg_dmabuf_ops_vmap,
 521         .mmap = vb2_dma_sg_dmabuf_ops_mmap,
 522         .release = vb2_dma_sg_dmabuf_ops_release,
 523 };
 524
 525 static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags)
 526 {
 527         struct vb2_dma_sg_buf *buf = buf_priv;
 528         struct dma_buf *dbuf;
 529         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 530
 531         exp_info.ops = &vb2_dma_sg_dmabuf_ops;
 532         exp_info.size = buf->size;
 533         exp_info.flags = flags;
 534         exp_info.priv = buf;
 535
 536         if (WARN_ON(!buf->dma_sgt))
 537                 return NULL;
 538
 539         dbuf = dma_buf_export(&exp_info);
 540         if (IS_ERR(dbuf))
 541                 return NULL;
 542
 543         /* dmabuf keeps reference to vb2 buffer */
 544         atomic_inc(&buf->refcount);
 545
 546         return dbuf;
 547 }
 548
 549 /*********************************************/
 550 /*       callbacks for DMABUF buffers        */
 551 /*********************************************/
 552
 553 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
 554 {
 555         struct vb2_dma_sg_buf *buf = mem_priv;
 556         struct sg_table *sgt;
 557
 558         if (WARN_ON(!buf->db_attach)) {
 559                 pr_err("trying to pin a non attached buffer\n");
 560                 return -EINVAL;
 561         }
 562
 563         if (WARN_ON(buf->dma_sgt)) {
 564                 pr_err("dmabuf buffer is already pinned\n");
 565                 return 0;
 566         }
 567
 568         /* get the associated scatterlist for this buffer */
 569         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 570         if (IS_ERR(sgt)) {
 571                 pr_err("Error getting dmabuf scatterlist\n");
 572                 return -EINVAL;
 573         }
 574
 575         buf->dma_sgt = sgt;
 576         buf->vaddr = NULL;
 577
 578         return 0;
 579 }
 580
 581 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
 582 {
 583         struct vb2_dma_sg_buf *buf = mem_priv;
 584         struct sg_table *sgt = buf->dma_sgt;
 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, buf->vaddr);
 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
 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
 618 static void *vb2_dma_sg_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 619         unsigned long size, enum dma_data_direction dma_dir)
 620 {
 621         struct vb2_dma_sg_conf *conf = alloc_ctx;
 622         struct vb2_dma_sg_buf *buf;
 623         struct dma_buf_attachment *dba;
 624
 625         if (dbuf->size < size)
 626                 return ERR_PTR(-EFAULT);
 627
 628         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 629         if (!buf)
 630                 return ERR_PTR(-ENOMEM);
 631
 632         buf->dev = conf->dev;
 633         /* create attachment for the dmabuf with the user device */
 634         dba = dma_buf_attach(dbuf, buf->dev);
 635         if (IS_ERR(dba)) {
 636                 pr_err("failed to attach dmabuf\n");
 637                 kfree(buf);
 638                 return dba;
 639         }
 640
 641         buf->dma_dir = dma_dir;
 642         buf->size = size;
 643         buf->db_attach = dba;
 644
 645         return buf;
 646 }
 647
 648 static void *vb2_dma_sg_cookie(void *buf_priv)
 649 {
 650         struct vb2_dma_sg_buf *buf = buf_priv;
 651
 652         return buf->dma_sgt;
 653 }
 654
 655 const struct vb2_mem_ops vb2_dma_sg_memops = {
 656         .alloc          = vb2_dma_sg_alloc,
 657         .put            = vb2_dma_sg_put,
 658         .get_userptr    = vb2_dma_sg_get_userptr,
 659         .put_userptr    = vb2_dma_sg_put_userptr,
 660         .prepare        = vb2_dma_sg_prepare,
 661         .finish         = vb2_dma_sg_finish,
 662         .vaddr          = vb2_dma_sg_vaddr,
 663         .mmap           = vb2_dma_sg_mmap,
 664         .num_users      = vb2_dma_sg_num_users,
 665         .get_dmabuf     = vb2_dma_sg_get_dmabuf,
 666         .map_dmabuf     = vb2_dma_sg_map_dmabuf,
 667         .unmap_dmabuf   = vb2_dma_sg_unmap_dmabuf,
 668         .attach_dmabuf  = vb2_dma_sg_attach_dmabuf,
 669         .detach_dmabuf  = vb2_dma_sg_detach_dmabuf,
 670         .cookie         = vb2_dma_sg_cookie,
 671 };
 672 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
 673
 674 void *vb2_dma_sg_init_ctx(struct device *dev)
 675 {
 676         struct vb2_dma_sg_conf *conf;
 677
 678         conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 679         if (!conf)
 680                 return ERR_PTR(-ENOMEM);
 681
 682         conf->dev = dev;
 683
 684         return conf;
 685 }
 686 EXPORT_SYMBOL_GPL(vb2_dma_sg_init_ctx);
 687
 688 void vb2_dma_sg_cleanup_ctx(void *alloc_ctx)
 689 {
 690         if (!IS_ERR_OR_NULL(alloc_ctx))
 691                 kfree(alloc_ctx);
 692 }
 693 EXPORT_SYMBOL_GPL(vb2_dma_sg_cleanup_ctx);
 694
 695 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
 696 MODULE_AUTHOR("Andrzej Pietrasiewicz");
 697 MODULE_LICENSE("GPL");