drivers/media/v4l2-core/videobuf2-dma-contig.c

   1 /*
   2  * videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2
   3  *
   4  * Copyright (C) 2010 Samsung Electronics
   5  *
   6  * Author: Pawel Osciak <pawel@osciak.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/dma-buf.h>
  14 #include <linux/module.h>
  15 #include <linux/scatterlist.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/dma-mapping.h>
  19
  20 #include <media/videobuf2-core.h>
  21 #include <media/videobuf2-dma-contig.h>
  22 #include <media/videobuf2-memops.h>
  23
  24 struct vb2_dc_conf {
  25         struct device           *dev;
  26 };
  27
  28 struct vb2_dc_buf {
  29         struct device                   *dev;
  30         void                            *vaddr;
  31         unsigned long                   size;
  32         dma_addr_t                      dma_addr;
  33         enum dma_data_direction         dma_dir;
  34         struct sg_table                 *dma_sgt;
  35
  36         /* MMAP related */
  37         struct vb2_vmarea_handler       handler;
  38         atomic_t                        refcount;
  39         struct sg_table                 *sgt_base;
  40
  41         /* USERPTR related */
  42         struct vm_area_struct           *vma;
  43
  44         /* DMABUF related */
  45         struct dma_buf_attachment       *db_attach;
  46 };
  47
  48 /*********************************************/
  49 /*        scatterlist table functions        */
  50 /*********************************************/
  51
  52
  53 static void vb2_dc_sgt_foreach_page(struct sg_table *sgt,
  54         void (*cb)(struct page *pg))
  55 {
  56         struct scatterlist *s;
  57         unsigned int i;
  58
  59         for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
  60                 struct page *page = sg_page(s);
  61                 unsigned int n_pages = PAGE_ALIGN(s->offset + s->length)
  62                         >> PAGE_SHIFT;
  63                 unsigned int j;
  64
  65                 for (j = 0; j < n_pages; ++j, ++page)
  66                         cb(page);
  67         }
  68 }
  69
  70 static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
  71 {
  72         struct scatterlist *s;
  73         dma_addr_t expected = sg_dma_address(sgt->sgl);
  74         unsigned int i;
  75         unsigned long size = 0;
  76
  77         for_each_sg(sgt->sgl, s, sgt->nents, i) {
  78                 if (sg_dma_address(s) != expected)
  79                         break;
  80                 expected = sg_dma_address(s) + sg_dma_len(s);
  81                 size += sg_dma_len(s);
  82         }
  83         return size;
  84 }
  85
  86 /*********************************************/
  87 /*         callbacks for all buffers         */
  88 /*********************************************/
  89
  90 static void *vb2_dc_cookie(void *buf_priv)
  91 {
  92         struct vb2_dc_buf *buf = buf_priv;
  93
  94         return &buf->dma_addr;
  95 }
  96
  97 static void *vb2_dc_vaddr(void *buf_priv)
  98 {
  99         struct vb2_dc_buf *buf = buf_priv;
 100
 101         return buf->vaddr;
 102 }
 103
 104 static unsigned int vb2_dc_num_users(void *buf_priv)
 105 {
 106         struct vb2_dc_buf *buf = buf_priv;
 107
 108         return atomic_read(&buf->refcount);
 109 }
 110
 111 static void vb2_dc_prepare(void *buf_priv)
 112 {
 113         struct vb2_dc_buf *buf = buf_priv;
 114         struct sg_table *sgt = buf->dma_sgt;
 115
 116         /* DMABUF exporter will flush the cache for us */
 117         if (!sgt || buf->db_attach)
 118                 return;
 119
 120         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 121 }
 122
 123 static void vb2_dc_finish(void *buf_priv)
 124 {
 125         struct vb2_dc_buf *buf = buf_priv;
 126         struct sg_table *sgt = buf->dma_sgt;
 127
 128         /* DMABUF exporter will flush the cache for us */
 129         if (!sgt || buf->db_attach)
 130                 return;
 131
 132         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 133 }
 134
 135 /*********************************************/
 136 /*        callbacks for MMAP buffers         */
 137 /*********************************************/
 138
 139 static void vb2_dc_put(void *buf_priv)
 140 {
 141         struct vb2_dc_buf *buf = buf_priv;
 142
 143         if (!atomic_dec_and_test(&buf->refcount))
 144                 return;
 145
 146         if (buf->sgt_base) {
 147                 sg_free_table(buf->sgt_base);
 148                 kfree(buf->sgt_base);
 149         }
 150         dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
 151         put_device(buf->dev);
 152         kfree(buf);
 153 }
 154
 155 static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_flags)
 156 {
 157         struct vb2_dc_conf *conf = alloc_ctx;
 158         struct device *dev = conf->dev;
 159         struct vb2_dc_buf *buf;
 160
 161         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 162         if (!buf)
 163                 return ERR_PTR(-ENOMEM);
 164
 165         buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr,
 166                                                 GFP_KERNEL | gfp_flags);
 167         if (!buf->vaddr) {
 168                 dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
 169                 kfree(buf);
 170                 return ERR_PTR(-ENOMEM);
 171         }
 172
 173         /* Prevent the device from being released while the buffer is used */
 174         buf->dev = get_device(dev);
 175         buf->size = size;
 176
 177         buf->handler.refcount = &buf->refcount;
 178         buf->handler.put = vb2_dc_put;
 179         buf->handler.arg = buf;
 180
 181         atomic_inc(&buf->refcount);
 182
 183         return buf;
 184 }
 185
 186 static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
 187 {
 188         struct vb2_dc_buf *buf = buf_priv;
 189         int ret;
 190
 191         if (!buf) {
 192                 printk(KERN_ERR "No buffer to map\n");
 193                 return -EINVAL;
 194         }
 195
 196         /*
 197          * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
 198          * map whole buffer
 199          */
 200         vma->vm_pgoff = 0;
 201
 202         ret = dma_mmap_coherent(buf->dev, vma, buf->vaddr,
 203                 buf->dma_addr, buf->size);
 204
 205         if (ret) {
 206                 pr_err("Remapping memory failed, error: %d\n", ret);
 207                 return ret;
 208         }
 209
 210         vma->vm_flags           |= VM_DONTEXPAND | VM_DONTDUMP;
 211         vma->vm_private_data    = &buf->handler;
 212         vma->vm_ops             = &vb2_common_vm_ops;
 213
 214         vma->vm_ops->open(vma);
 215
 216         pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
 217                 __func__, (unsigned long)buf->dma_addr, vma->vm_start,
 218                 buf->size);
 219
 220         return 0;
 221 }
 222
 223 /*********************************************/
 224 /*         DMABUF ops for exporters          */
 225 /*********************************************/
 226
 227 struct vb2_dc_attachment {
 228         struct sg_table sgt;
 229         enum dma_data_direction dir;
 230 };
 231
 232 static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 233         struct dma_buf_attachment *dbuf_attach)
 234 {
 235         struct vb2_dc_attachment *attach;
 236         unsigned int i;
 237         struct scatterlist *rd, *wr;
 238         struct sg_table *sgt;
 239         struct vb2_dc_buf *buf = dbuf->priv;
 240         int ret;
 241
 242         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 243         if (!attach)
 244                 return -ENOMEM;
 245
 246         sgt = &attach->sgt;
 247         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 248          * map the same scatter list to multiple attachments at the same time.
 249          */
 250         ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
 251         if (ret) {
 252                 kfree(attach);
 253                 return -ENOMEM;
 254         }
 255
 256         rd = buf->sgt_base->sgl;
 257         wr = sgt->sgl;
 258         for (i = 0; i < sgt->orig_nents; ++i) {
 259                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 260                 rd = sg_next(rd);
 261                 wr = sg_next(wr);
 262         }
 263
 264         attach->dir = DMA_NONE;
 265         dbuf_attach->priv = attach;
 266
 267         return 0;
 268 }
 269
 270 static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
 271         struct dma_buf_attachment *db_attach)
 272 {
 273         struct vb2_dc_attachment *attach = db_attach->priv;
 274         struct sg_table *sgt;
 275
 276         if (!attach)
 277                 return;
 278
 279         sgt = &attach->sgt;
 280
 281         /* release the scatterlist cache */
 282         if (attach->dir != DMA_NONE)
 283                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 284                         attach->dir);
 285         sg_free_table(sgt);
 286         kfree(attach);
 287         db_attach->priv = NULL;
 288 }
 289
 290 static struct sg_table *vb2_dc_dmabuf_ops_map(
 291         struct dma_buf_attachment *db_attach, enum dma_data_direction dir)
 292 {
 293         struct vb2_dc_attachment *attach = db_attach->priv;
 294         /* stealing dmabuf mutex to serialize map/unmap operations */
 295         struct mutex *lock = &db_attach->dmabuf->lock;
 296         struct sg_table *sgt;
 297         int ret;
 298
 299         mutex_lock(lock);
 300
 301         sgt = &attach->sgt;
 302         /* return previously mapped sg table */
 303         if (attach->dir == dir) {
 304                 mutex_unlock(lock);
 305                 return sgt;
 306         }
 307
 308         /* release any previous cache */
 309         if (attach->dir != DMA_NONE) {
 310                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 311                         attach->dir);
 312                 attach->dir = DMA_NONE;
 313         }
 314
 315         /* mapping to the client with new direction */
 316         ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dir);
 317         if (ret <= 0) {
 318                 pr_err("failed to map scatterlist\n");
 319                 mutex_unlock(lock);
 320                 return ERR_PTR(-EIO);
 321         }
 322
 323         attach->dir = dir;
 324
 325         mutex_unlock(lock);
 326
 327         return sgt;
 328 }
 329
 330 static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 331         struct sg_table *sgt, enum dma_data_direction dir)
 332 {
 333         /* nothing to be done here */
 334 }
 335
 336 static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
 337 {
 338         /* drop reference obtained in vb2_dc_get_dmabuf */
 339         vb2_dc_put(dbuf->priv);
 340 }
 341
 342 static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 343 {
 344         struct vb2_dc_buf *buf = dbuf->priv;
 345
 346         return buf->vaddr + pgnum * PAGE_SIZE;
 347 }
 348
 349 static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
 350 {
 351         struct vb2_dc_buf *buf = dbuf->priv;
 352
 353         return buf->vaddr;
 354 }
 355
 356 static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
 357         struct vm_area_struct *vma)
 358 {
 359         return vb2_dc_mmap(dbuf->priv, vma);
 360 }
 361
 362 static struct dma_buf_ops vb2_dc_dmabuf_ops = {
 363         .attach = vb2_dc_dmabuf_ops_attach,
 364         .detach = vb2_dc_dmabuf_ops_detach,
 365         .map_dma_buf = vb2_dc_dmabuf_ops_map,
 366         .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
 367         .kmap = vb2_dc_dmabuf_ops_kmap,
 368         .kmap_atomic = vb2_dc_dmabuf_ops_kmap,
 369         .vmap = vb2_dc_dmabuf_ops_vmap,
 370         .mmap = vb2_dc_dmabuf_ops_mmap,
 371         .release = vb2_dc_dmabuf_ops_release,
 372 };
 373
 374 static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
 375 {
 376         int ret;
 377         struct sg_table *sgt;
 378
 379         sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
 380         if (!sgt) {
 381                 dev_err(buf->dev, "failed to alloc sg table\n");
 382                 return NULL;
 383         }
 384
 385         ret = dma_get_sgtable(buf->dev, sgt, buf->vaddr, buf->dma_addr,
 386                 buf->size);
 387         if (ret < 0) {
 388                 dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
 389                 kfree(sgt);
 390                 return NULL;
 391         }
 392
 393         return sgt;
 394 }
 395
 396 static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv)
 397 {
 398         struct vb2_dc_buf *buf = buf_priv;
 399         struct dma_buf *dbuf;
 400
 401         if (!buf->sgt_base)
 402                 buf->sgt_base = vb2_dc_get_base_sgt(buf);
 403
 404         if (WARN_ON(!buf->sgt_base))
 405                 return NULL;
 406
 407         dbuf = dma_buf_export(buf, &vb2_dc_dmabuf_ops, buf->size, 0);
 408         if (IS_ERR(dbuf))
 409                 return NULL;
 410
 411         /* dmabuf keeps reference to vb2 buffer */
 412         atomic_inc(&buf->refcount);
 413
 414         return dbuf;
 415 }
 416
 417 /*********************************************/
 418 /*       callbacks for USERPTR buffers       */
 419 /*********************************************/
 420
 421 static inline int vma_is_io(struct vm_area_struct *vma)
 422 {
 423         return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
 424 }
 425
 426 static int vb2_dc_get_user_pages(unsigned long start, struct page **pages,
 427         int n_pages, struct vm_area_struct *vma, int write)
 428 {
 429         if (vma_is_io(vma)) {
 430                 unsigned int i;
 431
 432                 for (i = 0; i < n_pages; ++i, start += PAGE_SIZE) {
 433                         unsigned long pfn;
 434                         int ret = follow_pfn(vma, start, &pfn);
 435
 436                         if (ret) {
 437                                 pr_err("no page for address %lu\n", start);
 438                                 return ret;
 439                         }
 440                         pages[i] = pfn_to_page(pfn);
 441                 }
 442         } else {
 443                 int n;
 444
 445                 n = get_user_pages(current, current->mm, start & PAGE_MASK,
 446                         n_pages, write, 1, pages, NULL);
 447                 /* negative error means that no page was pinned */
 448                 n = max(n, 0);
 449                 if (n != n_pages) {
 450                         pr_err("got only %d of %d user pages\n", n, n_pages);
 451                         while (n)
 452                                 put_page(pages[--n]);
 453                         return -EFAULT;
 454                 }
 455         }
 456
 457         return 0;
 458 }
 459
 460 static void vb2_dc_put_dirty_page(struct page *page)
 461 {
 462         set_page_dirty_lock(page);
 463         put_page(page);
 464 }
 465
 466 static void vb2_dc_put_userptr(void *buf_priv)
 467 {
 468         struct vb2_dc_buf *buf = buf_priv;
 469         struct sg_table *sgt = buf->dma_sgt;
 470
 471         dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 472         if (!vma_is_io(buf->vma))
 473                 vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);
 474
 475         sg_free_table(sgt);
 476         kfree(sgt);
 477         vb2_put_vma(buf->vma);
 478         kfree(buf);
 479 }
 480
 481 static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 482         unsigned long size, int write)
 483 {
 484         struct vb2_dc_conf *conf = alloc_ctx;
 485         struct vb2_dc_buf *buf;
 486         unsigned long start;
 487         unsigned long end;
 488         unsigned long offset;
 489         struct page **pages;
 490         int n_pages;
 491         int ret = 0;
 492         struct vm_area_struct *vma;
 493         struct sg_table *sgt;
 494         unsigned long contig_size;
 495         unsigned long dma_align = dma_get_cache_alignment();
 496
 497         /* Only cache aligned DMA transfers are reliable */
 498         if (!IS_ALIGNED(vaddr | size, dma_align)) {
 499                 pr_debug("user data must be aligned to %lu bytes\n", dma_align);
 500                 return ERR_PTR(-EINVAL);
 501         }
 502
 503         if (!size) {
 504                 pr_debug("size is zero\n");
 505                 return ERR_PTR(-EINVAL);
 506         }
 507
 508         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 509         if (!buf)
 510                 return ERR_PTR(-ENOMEM);
 511
 512         buf->dev = conf->dev;
 513         buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
 514
 515         start = vaddr & PAGE_MASK;
 516         offset = vaddr & ~PAGE_MASK;
 517         end = PAGE_ALIGN(vaddr + size);
 518         n_pages = (end - start) >> PAGE_SHIFT;
 519
 520         pages = kmalloc(n_pages * sizeof(pages[0]), GFP_KERNEL);
 521         if (!pages) {
 522                 ret = -ENOMEM;
 523                 pr_err("failed to allocate pages table\n");
 524                 goto fail_buf;
 525         }
 526
 527         /* current->mm->mmap_sem is taken by videobuf2 core */
 528         vma = find_vma(current->mm, vaddr);
 529         if (!vma) {
 530                 pr_err("no vma for address %lu\n", vaddr);
 531                 ret = -EFAULT;
 532                 goto fail_pages;
 533         }
 534
 535         if (vma->vm_end < vaddr + size) {
 536                 pr_err("vma at %lu is too small for %lu bytes\n", vaddr, size);
 537                 ret = -EFAULT;
 538                 goto fail_pages;
 539         }
 540
 541         buf->vma = vb2_get_vma(vma);
 542         if (!buf->vma) {
 543                 pr_err("failed to copy vma\n");
 544                 ret = -ENOMEM;
 545                 goto fail_pages;
 546         }
 547
 548         /* extract page list from userspace mapping */
 549         ret = vb2_dc_get_user_pages(start, pages, n_pages, vma, write);
 550         if (ret) {
 551                 pr_err("failed to get user pages\n");
 552                 goto fail_vma;
 553         }
 554
 555         sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 556         if (!sgt) {
 557                 pr_err("failed to allocate sg table\n");
 558                 ret = -ENOMEM;
 559                 goto fail_get_user_pages;
 560         }
 561
 562         ret = sg_alloc_table_from_pages(sgt, pages, n_pages,
 563                 offset, size, GFP_KERNEL);
 564         if (ret) {
 565                 pr_err("failed to initialize sg table\n");
 566                 goto fail_sgt;
 567         }
 568
 569         /* pages are no longer needed */
 570         kfree(pages);
 571         pages = NULL;
 572
 573         sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents,
 574                 buf->dma_dir);
 575         if (sgt->nents <= 0) {
 576                 pr_err("failed to map scatterlist\n");
 577                 ret = -EIO;
 578                 goto fail_sgt_init;
 579         }
 580
 581         contig_size = vb2_dc_get_contiguous_size(sgt);
 582         if (contig_size < size) {
 583                 pr_err("contiguous mapping is too small %lu/%lu\n",
 584                         contig_size, size);
 585                 ret = -EFAULT;
 586                 goto fail_map_sg;
 587         }
 588
 589         buf->dma_addr = sg_dma_address(sgt->sgl);
 590         buf->size = size;
 591         buf->dma_sgt = sgt;
 592
 593         return buf;
 594
 595 fail_map_sg:
 596         dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 597
 598 fail_sgt_init:
 599         if (!vma_is_io(buf->vma))
 600                 vb2_dc_sgt_foreach_page(sgt, put_page);
 601         sg_free_table(sgt);
 602
 603 fail_sgt:
 604         kfree(sgt);
 605
 606 fail_get_user_pages:
 607         if (pages && !vma_is_io(buf->vma))
 608                 while (n_pages)
 609                         put_page(pages[--n_pages]);
 610
 611 fail_vma:
 612         vb2_put_vma(buf->vma);
 613
 614 fail_pages:
 615         kfree(pages); /* kfree is NULL-proof */
 616
 617 fail_buf:
 618         kfree(buf);
 619
 620         return ERR_PTR(ret);
 621 }
 622
 623 /*********************************************/
 624 /*       callbacks for DMABUF buffers        */
 625 /*********************************************/
 626
 627 static int vb2_dc_map_dmabuf(void *mem_priv)
 628 {
 629         struct vb2_dc_buf *buf = mem_priv;
 630         struct sg_table *sgt;
 631         unsigned long contig_size;
 632
 633         if (WARN_ON(!buf->db_attach)) {
 634                 pr_err("trying to pin a non attached buffer\n");
 635                 return -EINVAL;
 636         }
 637
 638         if (WARN_ON(buf->dma_sgt)) {
 639                 pr_err("dmabuf buffer is already pinned\n");
 640                 return 0;
 641         }
 642
 643         /* get the associated scatterlist for this buffer */
 644         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 645         if (IS_ERR_OR_NULL(sgt)) {
 646                 pr_err("Error getting dmabuf scatterlist\n");
 647                 return -EINVAL;
 648         }
 649
 650         /* checking if dmabuf is big enough to store contiguous chunk */
 651         contig_size = vb2_dc_get_contiguous_size(sgt);
 652         if (contig_size < buf->size) {
 653                 pr_err("contiguous chunk is too small %lu/%lu b\n",
 654                         contig_size, buf->size);
 655                 dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 656                 return -EFAULT;
 657         }
 658
 659         buf->dma_addr = sg_dma_address(sgt->sgl);
 660         buf->dma_sgt = sgt;
 661
 662         return 0;
 663 }
 664
 665 static void vb2_dc_unmap_dmabuf(void *mem_priv)
 666 {
 667         struct vb2_dc_buf *buf = mem_priv;
 668         struct sg_table *sgt = buf->dma_sgt;
 669
 670         if (WARN_ON(!buf->db_attach)) {
 671                 pr_err("trying to unpin a not attached buffer\n");
 672                 return;
 673         }
 674
 675         if (WARN_ON(!sgt)) {
 676                 pr_err("dmabuf buffer is already unpinned\n");
 677                 return;
 678         }
 679
 680         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 681
 682         buf->dma_addr = 0;
 683         buf->dma_sgt = NULL;
 684 }
 685
 686 static void vb2_dc_detach_dmabuf(void *mem_priv)
 687 {
 688         struct vb2_dc_buf *buf = mem_priv;
 689
 690         /* if vb2 works correctly you should never detach mapped buffer */
 691         if (WARN_ON(buf->dma_addr))
 692                 vb2_dc_unmap_dmabuf(buf);
 693
 694         /* detach this attachment */
 695         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 696         kfree(buf);
 697 }
 698
 699 static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 700         unsigned long size, int write)
 701 {
 702         struct vb2_dc_conf *conf = alloc_ctx;
 703         struct vb2_dc_buf *buf;
 704         struct dma_buf_attachment *dba;
 705
 706         if (dbuf->size < size)
 707                 return ERR_PTR(-EFAULT);
 708
 709         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 710         if (!buf)
 711                 return ERR_PTR(-ENOMEM);
 712
 713         buf->dev = conf->dev;
 714         /* create attachment for the dmabuf with the user device */
 715         dba = dma_buf_attach(dbuf, buf->dev);
 716         if (IS_ERR(dba)) {
 717                 pr_err("failed to attach dmabuf\n");
 718                 kfree(buf);
 719                 return dba;
 720         }
 721
 722         buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
 723         buf->size = size;
 724         buf->db_attach = dba;
 725
 726         return buf;
 727 }
 728
 729 /*********************************************/
 730 /*       DMA CONTIG exported functions       */
 731 /*********************************************/
 732
 733 const struct vb2_mem_ops vb2_dma_contig_memops = {
 734         .alloc          = vb2_dc_alloc,
 735         .put            = vb2_dc_put,
 736         .get_dmabuf     = vb2_dc_get_dmabuf,
 737         .cookie         = vb2_dc_cookie,
 738         .vaddr          = vb2_dc_vaddr,
 739         .mmap           = vb2_dc_mmap,
 740         .get_userptr    = vb2_dc_get_userptr,
 741         .put_userptr    = vb2_dc_put_userptr,
 742         .prepare        = vb2_dc_prepare,
 743         .finish         = vb2_dc_finish,
 744         .map_dmabuf     = vb2_dc_map_dmabuf,
 745         .unmap_dmabuf   = vb2_dc_unmap_dmabuf,
 746         .attach_dmabuf  = vb2_dc_attach_dmabuf,
 747         .detach_dmabuf  = vb2_dc_detach_dmabuf,
 748         .num_users      = vb2_dc_num_users,
 749 };
 750 EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
 751
 752 void *vb2_dma_contig_init_ctx(struct device *dev)
 753 {
 754         struct vb2_dc_conf *conf;
 755
 756         conf = kzalloc(sizeof *conf, GFP_KERNEL);
 757         if (!conf)
 758                 return ERR_PTR(-ENOMEM);
 759
 760         conf->dev = dev;
 761
 762         return conf;
 763 }
 764 EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);
 765
 766 void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
 767 {
 768         kfree(alloc_ctx);
 769 }
 770 EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
 771
 772 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 773 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 774 MODULE_LICENSE("GPL");