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