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         int                             offset;
  42         enum dma_data_direction         dma_dir;
  43         struct sg_table                 sg_table;
  44         /*
  45          * This will point to sg_table when used with the MMAP or USERPTR
  46          * memory model, and to the dma_buf sglist when used with the
  47          * DMABUF memory model.
  48          */
  49         struct sg_table                 *dma_sgt;
  50         size_t                          size;
  51         unsigned int                    num_pages;
  52         atomic_t                        refcount;
  53         struct vb2_vmarea_handler       handler;
  54         struct vm_area_struct           *vma;
  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
 111         if (WARN_ON(alloc_ctx == NULL))
 112                 return NULL;
 113         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 114         if (!buf)
 115                 return NULL;
 116
 117         buf->vaddr = NULL;
 118         buf->dma_dir = dma_dir;
 119         buf->offset = 0;
 120         buf->size = size;
 121         /* size is already page aligned */
 122         buf->num_pages = size >> PAGE_SHIFT;
 123         buf->dma_sgt = &buf->sg_table;
 124
 125         buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
 126                              GFP_KERNEL);
 127         if (!buf->pages)
 128                 goto fail_pages_array_alloc;
 129
 130         ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags);
 131         if (ret)
 132                 goto fail_pages_alloc;
 133
 134         ret = sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 135                         buf->num_pages, 0, size, GFP_KERNEL);
 136         if (ret)
 137                 goto fail_table_alloc;
 138
 139         /* Prevent the device from being released while the buffer is used */
 140         buf->dev = get_device(conf->dev);
 141
 142         sgt = &buf->sg_table;
 143         if (dma_map_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir) == 0)
 144                 goto fail_map;
 145         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 146
 147         buf->handler.refcount = &buf->refcount;
 148         buf->handler.put = vb2_dma_sg_put;
 149         buf->handler.arg = buf;
 150
 151         atomic_inc(&buf->refcount);
 152
 153         dprintk(1, "%s: Allocated buffer of %d pages\n",
 154                 __func__, buf->num_pages);
 155         return buf;
 156
 157 fail_map:
 158         put_device(buf->dev);
 159         sg_free_table(buf->dma_sgt);
 160 fail_table_alloc:
 161         num_pages = buf->num_pages;
 162         while (num_pages--)
 163                 __free_page(buf->pages[num_pages]);
 164 fail_pages_alloc:
 165         kfree(buf->pages);
 166 fail_pages_array_alloc:
 167         kfree(buf);
 168         return NULL;
 169 }
 170
 171 static void vb2_dma_sg_put(void *buf_priv)
 172 {
 173         struct vb2_dma_sg_buf *buf = buf_priv;
 174         struct sg_table *sgt = &buf->sg_table;
 175         int i = buf->num_pages;
 176
 177         if (atomic_dec_and_test(&buf->refcount)) {
 178                 dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
 179                         buf->num_pages);
 180                 dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 181                 if (buf->vaddr)
 182                         vm_unmap_ram(buf->vaddr, buf->num_pages);
 183                 sg_free_table(buf->dma_sgt);
 184                 while (--i >= 0)
 185                         __free_page(buf->pages[i]);
 186                 kfree(buf->pages);
 187                 put_device(buf->dev);
 188                 kfree(buf);
 189         }
 190 }
 191
 192 static void vb2_dma_sg_prepare(void *buf_priv)
 193 {
 194         struct vb2_dma_sg_buf *buf = buf_priv;
 195         struct sg_table *sgt = buf->dma_sgt;
 196
 197         /* DMABUF exporter will flush the cache for us */
 198         if (buf->db_attach)
 199                 return;
 200
 201         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 202 }
 203
 204 static void vb2_dma_sg_finish(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_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 214 }
 215
 216 static inline int vma_is_io(struct vm_area_struct *vma)
 217 {
 218         return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
 219 }
 220
 221 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 222                                     unsigned long size,
 223                                     enum dma_data_direction dma_dir)
 224 {
 225         struct vb2_dma_sg_conf *conf = alloc_ctx;
 226         struct vb2_dma_sg_buf *buf;
 227         unsigned long first, last;
 228         int num_pages_from_user;
 229         struct vm_area_struct *vma;
 230         struct sg_table *sgt;
 231
 232         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 233         if (!buf)
 234                 return NULL;
 235
 236         buf->vaddr = NULL;
 237         buf->dev = conf->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
 243         first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
 244         last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
 245         buf->num_pages = last - first + 1;
 246
 247         buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
 248                              GFP_KERNEL);
 249         if (!buf->pages)
 250                 goto userptr_fail_alloc_pages;
 251
 252         vma = find_vma(current->mm, vaddr);
 253         if (!vma) {
 254                 dprintk(1, "no vma for address %lu\n", vaddr);
 255                 goto userptr_fail_find_vma;
 256         }
 257
 258         if (vma->vm_end < vaddr + size) {
 259                 dprintk(1, "vma at %lu is too small for %lu bytes\n",
 260                         vaddr, size);
 261                 goto userptr_fail_find_vma;
 262         }
 263
 264         buf->vma = vb2_get_vma(vma);
 265         if (!buf->vma) {
 266                 dprintk(1, "failed to copy vma\n");
 267                 goto userptr_fail_find_vma;
 268         }
 269
 270         if (vma_is_io(buf->vma)) {
 271                 for (num_pages_from_user = 0;
 272                      num_pages_from_user < buf->num_pages;
 273                      ++num_pages_from_user, vaddr += PAGE_SIZE) {
 274                         unsigned long pfn;
 275
 276                         if (follow_pfn(vma, vaddr, &pfn)) {
 277                                 dprintk(1, "no page for address %lu\n", vaddr);
 278                                 break;
 279                         }
 280                         buf->pages[num_pages_from_user] = pfn_to_page(pfn);
 281                 }
 282         } else
 283                 num_pages_from_user = get_user_pages(current, current->mm,
 284                                              vaddr & PAGE_MASK,
 285                                              buf->num_pages,
 286                                              buf->dma_dir == DMA_FROM_DEVICE,
 287                                              1, /* force */
 288                                              buf->pages,
 289                                              NULL);
 290
 291         if (num_pages_from_user != buf->num_pages)
 292                 goto userptr_fail_get_user_pages;
 293
 294         if (sg_alloc_table_from_pages(buf->dma_sgt, buf->pages,
 295                         buf->num_pages, buf->offset, size, 0))
 296                 goto userptr_fail_alloc_table_from_pages;
 297
 298         sgt = &buf->sg_table;
 299         if (dma_map_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir) == 0)
 300                 goto userptr_fail_map;
 301         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 302         return buf;
 303
 304 userptr_fail_map:
 305         sg_free_table(&buf->sg_table);
 306 userptr_fail_alloc_table_from_pages:
 307 userptr_fail_get_user_pages:
 308         dprintk(1, "get_user_pages requested/got: %d/%d]\n",
 309                 buf->num_pages, num_pages_from_user);
 310         if (!vma_is_io(buf->vma))
 311                 while (--num_pages_from_user >= 0)
 312                         put_page(buf->pages[num_pages_from_user]);
 313         vb2_put_vma(buf->vma);
 314 userptr_fail_find_vma:
 315         kfree(buf->pages);
 316 userptr_fail_alloc_pages:
 317         kfree(buf);
 318         return NULL;
 319 }
 320
 321 /*
 322  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 323  *               be used
 324  */
 325 static void vb2_dma_sg_put_userptr(void *buf_priv)
 326 {
 327         struct vb2_dma_sg_buf *buf = buf_priv;
 328         struct sg_table *sgt = &buf->sg_table;
 329         int i = buf->num_pages;
 330
 331         dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
 332                __func__, buf->num_pages);
 333         dma_unmap_sg(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 334         if (buf->vaddr)
 335                 vm_unmap_ram(buf->vaddr, buf->num_pages);
 336         sg_free_table(buf->dma_sgt);
 337         while (--i >= 0) {
 338                 if (buf->dma_dir == DMA_FROM_DEVICE)
 339                         set_page_dirty_lock(buf->pages[i]);
 340                 if (!vma_is_io(buf->vma))
 341                         put_page(buf->pages[i]);
 342         }
 343         kfree(buf->pages);
 344         vb2_put_vma(buf->vma);
 345         kfree(buf);
 346 }
 347
 348 static void *vb2_dma_sg_vaddr(void *buf_priv)
 349 {
 350         struct vb2_dma_sg_buf *buf = buf_priv;
 351
 352         BUG_ON(!buf);
 353
 354         if (!buf->vaddr) {
 355                 if (buf->db_attach)
 356                         buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
 357                 else
 358                         buf->vaddr = vm_map_ram(buf->pages,
 359                                         buf->num_pages, -1, PAGE_KERNEL);
 360         }
 361
 362         /* add offset in case userptr is not page-aligned */
 363         return buf->vaddr ? buf->vaddr + buf->offset : NULL;
 364 }
 365
 366 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
 367 {
 368         struct vb2_dma_sg_buf *buf = buf_priv;
 369
 370         return atomic_read(&buf->refcount);
 371 }
 372
 373 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
 374 {
 375         struct vb2_dma_sg_buf *buf = buf_priv;
 376         unsigned long uaddr = vma->vm_start;
 377         unsigned long usize = vma->vm_end - vma->vm_start;
 378         int i = 0;
 379
 380         if (!buf) {
 381                 printk(KERN_ERR "No memory to map\n");
 382                 return -EINVAL;
 383         }
 384
 385         do {
 386                 int ret;
 387
 388                 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
 389                 if (ret) {
 390                         printk(KERN_ERR "Remapping memory, error: %d\n", ret);
 391                         return ret;
 392                 }
 393
 394                 uaddr += PAGE_SIZE;
 395                 usize -= PAGE_SIZE;
 396         } while (usize > 0);
 397
 398
 399         /*
 400          * Use common vm_area operations to track buffer refcount.
 401          */
 402         vma->vm_private_data    = &buf->handler;
 403         vma->vm_ops             = &vb2_common_vm_ops;
 404
 405         vma->vm_ops->open(vma);
 406
 407         return 0;
 408 }
 409
 410 /*********************************************/
 411 /*         DMABUF ops for exporters          */
 412 /*********************************************/
 413
 414 struct vb2_dma_sg_attachment {
 415         struct sg_table sgt;
 416         enum dma_data_direction dma_dir;
 417 };
 418
 419 static int vb2_dma_sg_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 420         struct dma_buf_attachment *dbuf_attach)
 421 {
 422         struct vb2_dma_sg_attachment *attach;
 423         unsigned int i;
 424         struct scatterlist *rd, *wr;
 425         struct sg_table *sgt;
 426         struct vb2_dma_sg_buf *buf = dbuf->priv;
 427         int ret;
 428
 429         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 430         if (!attach)
 431                 return -ENOMEM;
 432
 433         sgt = &attach->sgt;
 434         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 435          * map the same scatter list to multiple attachments at the same time.
 436          */
 437         ret = sg_alloc_table(sgt, buf->dma_sgt->orig_nents, GFP_KERNEL);
 438         if (ret) {
 439                 kfree(attach);
 440                 return -ENOMEM;
 441         }
 442
 443         rd = buf->dma_sgt->sgl;
 444         wr = sgt->sgl;
 445         for (i = 0; i < sgt->orig_nents; ++i) {
 446                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 447                 rd = sg_next(rd);
 448                 wr = sg_next(wr);
 449         }
 450
 451         attach->dma_dir = DMA_NONE;
 452         dbuf_attach->priv = attach;
 453
 454         return 0;
 455 }
 456
 457 static void vb2_dma_sg_dmabuf_ops_detach(struct dma_buf *dbuf,
 458         struct dma_buf_attachment *db_attach)
 459 {
 460         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 461         struct sg_table *sgt;
 462
 463         if (!attach)
 464                 return;
 465
 466         sgt = &attach->sgt;
 467
 468         /* release the scatterlist cache */
 469         if (attach->dma_dir != DMA_NONE)
 470                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 471                         attach->dma_dir);
 472         sg_free_table(sgt);
 473         kfree(attach);
 474         db_attach->priv = NULL;
 475 }
 476
 477 static struct sg_table *vb2_dma_sg_dmabuf_ops_map(
 478         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 479 {
 480         struct vb2_dma_sg_attachment *attach = db_attach->priv;
 481         /* stealing dmabuf mutex to serialize map/unmap operations */
 482         struct mutex *lock = &db_attach->dmabuf->lock;
 483         struct sg_table *sgt;
 484         int ret;
 485
 486         mutex_lock(lock);
 487
 488         sgt = &attach->sgt;
 489         /* return previously mapped sg table */
 490         if (attach->dma_dir == dma_dir) {
 491                 mutex_unlock(lock);
 492                 return sgt;
 493         }
 494
 495         /* release any previous cache */
 496         if (attach->dma_dir != DMA_NONE) {
 497                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 498                         attach->dma_dir);
 499                 attach->dma_dir = DMA_NONE;
 500         }
 501
 502         /* mapping to the client with new direction */
 503         ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dma_dir);
 504         if (ret <= 0) {
 505                 pr_err("failed to map scatterlist\n");
 506                 mutex_unlock(lock);
 507                 return ERR_PTR(-EIO);
 508         }
 509
 510         attach->dma_dir = dma_dir;
 511
 512         mutex_unlock(lock);
 513
 514         return sgt;
 515 }
 516
 517 static void vb2_dma_sg_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 518         struct sg_table *sgt, enum dma_data_direction dma_dir)
 519 {
 520         /* nothing to be done here */
 521 }
 522
 523 static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
 524 {
 525         /* drop reference obtained in vb2_dma_sg_get_dmabuf */
 526         vb2_dma_sg_put(dbuf->priv);
 527 }
 528
 529 static void *vb2_dma_sg_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 530 {
 531         struct vb2_dma_sg_buf *buf = dbuf->priv;
 532
 533         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 534 }
 535
 536 static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
 537 {
 538         struct vb2_dma_sg_buf *buf = dbuf->priv;
 539
 540         return vb2_dma_sg_vaddr(buf);
 541 }
 542
 543 static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
 544         struct vm_area_struct *vma)
 545 {
 546         return vb2_dma_sg_mmap(dbuf->priv, vma);
 547 }
 548
 549 static struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 550         .attach = vb2_dma_sg_dmabuf_ops_attach,
 551         .detach = vb2_dma_sg_dmabuf_ops_detach,
 552         .map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 553         .unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
 554         .kmap = vb2_dma_sg_dmabuf_ops_kmap,
 555         .kmap_atomic = vb2_dma_sg_dmabuf_ops_kmap,
 556         .vmap = vb2_dma_sg_dmabuf_ops_vmap,
 557         .mmap = vb2_dma_sg_dmabuf_ops_mmap,
 558         .release = vb2_dma_sg_dmabuf_ops_release,
 559 };
 560
 561 static struct dma_buf *vb2_dma_sg_get_dmabuf(void *buf_priv, unsigned long flags)
 562 {
 563         struct vb2_dma_sg_buf *buf = buf_priv;
 564         struct dma_buf *dbuf;
 565
 566         if (WARN_ON(!buf->dma_sgt))
 567                 return NULL;
 568
 569         dbuf = dma_buf_export(buf, &vb2_dma_sg_dmabuf_ops, buf->size, flags, NULL);
 570         if (IS_ERR(dbuf))
 571                 return NULL;
 572
 573         /* dmabuf keeps reference to vb2 buffer */
 574         atomic_inc(&buf->refcount);
 575
 576         return dbuf;
 577 }
 578
 579 /*********************************************/
 580 /*       callbacks for DMABUF buffers        */
 581 /*********************************************/
 582
 583 static int vb2_dma_sg_map_dmabuf(void *mem_priv)
 584 {
 585         struct vb2_dma_sg_buf *buf = mem_priv;
 586         struct sg_table *sgt;
 587
 588         if (WARN_ON(!buf->db_attach)) {
 589                 pr_err("trying to pin a non attached buffer\n");
 590                 return -EINVAL;
 591         }
 592
 593         if (WARN_ON(buf->dma_sgt)) {
 594                 pr_err("dmabuf buffer is already pinned\n");
 595                 return 0;
 596         }
 597
 598         /* get the associated scatterlist for this buffer */
 599         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 600         if (IS_ERR(sgt)) {
 601                 pr_err("Error getting dmabuf scatterlist\n");
 602                 return -EINVAL;
 603         }
 604
 605         buf->dma_sgt = sgt;
 606         buf->vaddr = NULL;
 607
 608         return 0;
 609 }
 610
 611 static void vb2_dma_sg_unmap_dmabuf(void *mem_priv)
 612 {
 613         struct vb2_dma_sg_buf *buf = mem_priv;
 614         struct sg_table *sgt = buf->dma_sgt;
 615
 616         if (WARN_ON(!buf->db_attach)) {
 617                 pr_err("trying to unpin a not attached buffer\n");
 618                 return;
 619         }
 620
 621         if (WARN_ON(!sgt)) {
 622                 pr_err("dmabuf buffer is already unpinned\n");
 623                 return;
 624         }
 625
 626         if (buf->vaddr) {
 627                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 628                 buf->vaddr = NULL;
 629         }
 630         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 631
 632         buf->dma_sgt = NULL;
 633 }
 634
 635 static void vb2_dma_sg_detach_dmabuf(void *mem_priv)
 636 {
 637         struct vb2_dma_sg_buf *buf = mem_priv;
 638
 639         /* if vb2 works correctly you should never detach mapped buffer */
 640         if (WARN_ON(buf->dma_sgt))
 641                 vb2_dma_sg_unmap_dmabuf(buf);
 642
 643         /* detach this attachment */
 644         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 645         kfree(buf);
 646 }
 647
 648 static void *vb2_dma_sg_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 649         unsigned long size, enum dma_data_direction dma_dir)
 650 {
 651         struct vb2_dma_sg_conf *conf = alloc_ctx;
 652         struct vb2_dma_sg_buf *buf;
 653         struct dma_buf_attachment *dba;
 654
 655         if (dbuf->size < size)
 656                 return ERR_PTR(-EFAULT);
 657
 658         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 659         if (!buf)
 660                 return ERR_PTR(-ENOMEM);
 661
 662         buf->dev = conf->dev;
 663         /* create attachment for the dmabuf with the user device */
 664         dba = dma_buf_attach(dbuf, buf->dev);
 665         if (IS_ERR(dba)) {
 666                 pr_err("failed to attach dmabuf\n");
 667                 kfree(buf);
 668                 return dba;
 669         }
 670
 671         buf->dma_dir = dma_dir;
 672         buf->size = size;
 673         buf->db_attach = dba;
 674
 675         return buf;
 676 }
 677
 678 static void *vb2_dma_sg_cookie(void *buf_priv)
 679 {
 680         struct vb2_dma_sg_buf *buf = buf_priv;
 681
 682         return buf->dma_sgt;
 683 }
 684
 685 const struct vb2_mem_ops vb2_dma_sg_memops = {
 686         .alloc          = vb2_dma_sg_alloc,
 687         .put            = vb2_dma_sg_put,
 688         .get_userptr    = vb2_dma_sg_get_userptr,
 689         .put_userptr    = vb2_dma_sg_put_userptr,
 690         .prepare        = vb2_dma_sg_prepare,
 691         .finish         = vb2_dma_sg_finish,
 692         .vaddr          = vb2_dma_sg_vaddr,
 693         .mmap           = vb2_dma_sg_mmap,
 694         .num_users      = vb2_dma_sg_num_users,
 695         .get_dmabuf     = vb2_dma_sg_get_dmabuf,
 696         .map_dmabuf     = vb2_dma_sg_map_dmabuf,
 697         .unmap_dmabuf   = vb2_dma_sg_unmap_dmabuf,
 698         .attach_dmabuf  = vb2_dma_sg_attach_dmabuf,
 699         .detach_dmabuf  = vb2_dma_sg_detach_dmabuf,
 700         .cookie         = vb2_dma_sg_cookie,
 701 };
 702 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
 703
 704 void *vb2_dma_sg_init_ctx(struct device *dev)
 705 {
 706         struct vb2_dma_sg_conf *conf;
 707
 708         conf = kzalloc(sizeof(*conf), GFP_KERNEL);
 709         if (!conf)
 710                 return ERR_PTR(-ENOMEM);
 711
 712         conf->dev = dev;
 713
 714         return conf;
 715 }
 716 EXPORT_SYMBOL_GPL(vb2_dma_sg_init_ctx);
 717
 718 void vb2_dma_sg_cleanup_ctx(void *alloc_ctx)
 719 {
 720         if (!IS_ERR_OR_NULL(alloc_ctx))
 721                 kfree(alloc_ctx);
 722 }
 723 EXPORT_SYMBOL_GPL(vb2_dma_sg_cleanup_ctx);
 724
 725 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
 726 MODULE_AUTHOR("Andrzej Pietrasiewicz");
 727 MODULE_LICENSE("GPL");