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-v4l2.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         void                            *cookie;
  33         dma_addr_t                      dma_addr;
  34         struct dma_attrs                attrs;
  35         enum dma_data_direction         dma_dir;
  36         struct sg_table                 *dma_sgt;
  37         struct frame_vector             *vec;
  38
  39         /* MMAP related */
  40         struct vb2_vmarea_handler       handler;
  41         atomic_t                        refcount;
  42         struct sg_table                 *sgt_base;
  43
  44         /* DMABUF related */
  45         struct dma_buf_attachment       *db_attach;
  46 };
  47
  48 /*********************************************/
  49 /*        scatterlist table functions        */
  50 /*********************************************/
  51
  52 static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
  53 {
  54         struct scatterlist *s;
  55         dma_addr_t expected = sg_dma_address(sgt->sgl);
  56         unsigned int i;
  57         unsigned long size = 0;
  58
  59         for_each_sg(sgt->sgl, s, sgt->nents, i) {
  60                 if (sg_dma_address(s) != expected)
  61                         break;
  62                 expected = sg_dma_address(s) + sg_dma_len(s);
  63                 size += sg_dma_len(s);
  64         }
  65         return size;
  66 }
  67
  68 /*********************************************/
  69 /*         callbacks for all buffers         */
  70 /*********************************************/
  71
  72 static void *vb2_dc_cookie(void *buf_priv)
  73 {
  74         struct vb2_dc_buf *buf = buf_priv;
  75
  76         return &buf->dma_addr;
  77 }
  78
  79 static void *vb2_dc_vaddr(void *buf_priv)
  80 {
  81         struct vb2_dc_buf *buf = buf_priv;
  82
  83         if (!buf->vaddr && buf->db_attach)
  84                 buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
  85
  86         return buf->vaddr;
  87 }
  88
  89 static unsigned int vb2_dc_num_users(void *buf_priv)
  90 {
  91         struct vb2_dc_buf *buf = buf_priv;
  92
  93         return atomic_read(&buf->refcount);
  94 }
  95
  96 static void vb2_dc_prepare(void *buf_priv)
  97 {
  98         struct vb2_dc_buf *buf = buf_priv;
  99         struct sg_table *sgt = buf->dma_sgt;
 100
 101         /* DMABUF exporter will flush the cache for us */
 102         if (!sgt || buf->db_attach)
 103                 return;
 104
 105         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
 106                                buf->dma_dir);
 107 }
 108
 109 static void vb2_dc_finish(void *buf_priv)
 110 {
 111         struct vb2_dc_buf *buf = buf_priv;
 112         struct sg_table *sgt = buf->dma_sgt;
 113
 114         /* DMABUF exporter will flush the cache for us */
 115         if (!sgt || buf->db_attach)
 116                 return;
 117
 118         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 119 }
 120
 121 /*********************************************/
 122 /*        callbacks for MMAP buffers         */
 123 /*********************************************/
 124
 125 static void vb2_dc_put(void *buf_priv)
 126 {
 127         struct vb2_dc_buf *buf = buf_priv;
 128
 129         if (!atomic_dec_and_test(&buf->refcount))
 130                 return;
 131
 132         if (buf->sgt_base) {
 133                 sg_free_table(buf->sgt_base);
 134                 kfree(buf->sgt_base);
 135         }
 136         dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr,
 137                         &buf->attrs);
 138         put_device(buf->dev);
 139         kfree(buf);
 140 }
 141
 142 static void *vb2_dc_alloc(void *alloc_ctx, const struct dma_attrs *attrs,
 143                           unsigned long size, enum dma_data_direction dma_dir,
 144                           gfp_t gfp_flags)
 145 {
 146         struct vb2_dc_conf *conf = alloc_ctx;
 147         struct device *dev = conf->dev;
 148         struct vb2_dc_buf *buf;
 149
 150         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 151         if (!buf)
 152                 return ERR_PTR(-ENOMEM);
 153
 154         if (attrs)
 155                 buf->attrs = *attrs;
 156         buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr,
 157                                         GFP_KERNEL | gfp_flags, &buf->attrs);
 158         if (!buf->cookie) {
 159                 dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
 160                 kfree(buf);
 161                 return ERR_PTR(-ENOMEM);
 162         }
 163
 164         if (!dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, &buf->attrs))
 165                 buf->vaddr = buf->cookie;
 166
 167         /* Prevent the device from being released while the buffer is used */
 168         buf->dev = get_device(dev);
 169         buf->size = size;
 170         buf->dma_dir = dma_dir;
 171
 172         buf->handler.refcount = &buf->refcount;
 173         buf->handler.put = vb2_dc_put;
 174         buf->handler.arg = buf;
 175
 176         atomic_inc(&buf->refcount);
 177
 178         return buf;
 179 }
 180
 181 static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
 182 {
 183         struct vb2_dc_buf *buf = buf_priv;
 184         int ret;
 185
 186         if (!buf) {
 187                 printk(KERN_ERR "No buffer to map\n");
 188                 return -EINVAL;
 189         }
 190
 191         /*
 192          * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
 193          * map whole buffer
 194          */
 195         vma->vm_pgoff = 0;
 196
 197         ret = dma_mmap_attrs(buf->dev, vma, buf->cookie,
 198                 buf->dma_addr, buf->size, &buf->attrs);
 199
 200         if (ret) {
 201                 pr_err("Remapping memory failed, error: %d\n", ret);
 202                 return ret;
 203         }
 204
 205         vma->vm_flags           |= VM_DONTEXPAND | VM_DONTDUMP;
 206         vma->vm_private_data    = &buf->handler;
 207         vma->vm_ops             = &vb2_common_vm_ops;
 208
 209         vma->vm_ops->open(vma);
 210
 211         pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
 212                 __func__, (unsigned long)buf->dma_addr, vma->vm_start,
 213                 buf->size);
 214
 215         return 0;
 216 }
 217
 218 /*********************************************/
 219 /*         DMABUF ops for exporters          */
 220 /*********************************************/
 221
 222 struct vb2_dc_attachment {
 223         struct sg_table sgt;
 224         enum dma_data_direction dma_dir;
 225 };
 226
 227 static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 228         struct dma_buf_attachment *dbuf_attach)
 229 {
 230         struct vb2_dc_attachment *attach;
 231         unsigned int i;
 232         struct scatterlist *rd, *wr;
 233         struct sg_table *sgt;
 234         struct vb2_dc_buf *buf = dbuf->priv;
 235         int ret;
 236
 237         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 238         if (!attach)
 239                 return -ENOMEM;
 240
 241         sgt = &attach->sgt;
 242         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 243          * map the same scatter list to multiple attachments at the same time.
 244          */
 245         ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
 246         if (ret) {
 247                 kfree(attach);
 248                 return -ENOMEM;
 249         }
 250
 251         rd = buf->sgt_base->sgl;
 252         wr = sgt->sgl;
 253         for (i = 0; i < sgt->orig_nents; ++i) {
 254                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 255                 rd = sg_next(rd);
 256                 wr = sg_next(wr);
 257         }
 258
 259         attach->dma_dir = DMA_NONE;
 260         dbuf_attach->priv = attach;
 261
 262         return 0;
 263 }
 264
 265 static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
 266         struct dma_buf_attachment *db_attach)
 267 {
 268         struct vb2_dc_attachment *attach = db_attach->priv;
 269         struct sg_table *sgt;
 270
 271         if (!attach)
 272                 return;
 273
 274         sgt = &attach->sgt;
 275
 276         /* release the scatterlist cache */
 277         if (attach->dma_dir != DMA_NONE)
 278                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 279                         attach->dma_dir);
 280         sg_free_table(sgt);
 281         kfree(attach);
 282         db_attach->priv = NULL;
 283 }
 284
 285 static struct sg_table *vb2_dc_dmabuf_ops_map(
 286         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 287 {
 288         struct vb2_dc_attachment *attach = db_attach->priv;
 289         /* stealing dmabuf mutex to serialize map/unmap operations */
 290         struct mutex *lock = &db_attach->dmabuf->lock;
 291         struct sg_table *sgt;
 292
 293         mutex_lock(lock);
 294
 295         sgt = &attach->sgt;
 296         /* return previously mapped sg table */
 297         if (attach->dma_dir == dma_dir) {
 298                 mutex_unlock(lock);
 299                 return sgt;
 300         }
 301
 302         /* release any previous cache */
 303         if (attach->dma_dir != DMA_NONE) {
 304                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 305                         attach->dma_dir);
 306                 attach->dma_dir = DMA_NONE;
 307         }
 308
 309         /* mapping to the client with new direction */
 310         sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 311                                 dma_dir);
 312         if (!sgt->nents) {
 313                 pr_err("failed to map scatterlist\n");
 314                 mutex_unlock(lock);
 315                 return ERR_PTR(-EIO);
 316         }
 317
 318         attach->dma_dir = dma_dir;
 319
 320         mutex_unlock(lock);
 321
 322         return sgt;
 323 }
 324
 325 static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 326         struct sg_table *sgt, enum dma_data_direction dma_dir)
 327 {
 328         /* nothing to be done here */
 329 }
 330
 331 static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
 332 {
 333         /* drop reference obtained in vb2_dc_get_dmabuf */
 334         vb2_dc_put(dbuf->priv);
 335 }
 336
 337 static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 338 {
 339         struct vb2_dc_buf *buf = dbuf->priv;
 340
 341         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 342 }
 343
 344 static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
 345 {
 346         struct vb2_dc_buf *buf = dbuf->priv;
 347
 348         return buf->vaddr;
 349 }
 350
 351 static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
 352         struct vm_area_struct *vma)
 353 {
 354         return vb2_dc_mmap(dbuf->priv, vma);
 355 }
 356
 357 static struct dma_buf_ops vb2_dc_dmabuf_ops = {
 358         .attach = vb2_dc_dmabuf_ops_attach,
 359         .detach = vb2_dc_dmabuf_ops_detach,
 360         .map_dma_buf = vb2_dc_dmabuf_ops_map,
 361         .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
 362         .kmap = vb2_dc_dmabuf_ops_kmap,
 363         .kmap_atomic = vb2_dc_dmabuf_ops_kmap,
 364         .vmap = vb2_dc_dmabuf_ops_vmap,
 365         .mmap = vb2_dc_dmabuf_ops_mmap,
 366         .release = vb2_dc_dmabuf_ops_release,
 367 };
 368
 369 static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
 370 {
 371         int ret;
 372         struct sg_table *sgt;
 373
 374         sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
 375         if (!sgt) {
 376                 dev_err(buf->dev, "failed to alloc sg table\n");
 377                 return NULL;
 378         }
 379
 380         ret = dma_get_sgtable_attrs(buf->dev, sgt, buf->cookie, buf->dma_addr,
 381                 buf->size, &buf->attrs);
 382         if (ret < 0) {
 383                 dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
 384                 kfree(sgt);
 385                 return NULL;
 386         }
 387
 388         return sgt;
 389 }
 390
 391 static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
 392 {
 393         struct vb2_dc_buf *buf = buf_priv;
 394         struct dma_buf *dbuf;
 395         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 396
 397         exp_info.ops = &vb2_dc_dmabuf_ops;
 398         exp_info.size = buf->size;
 399         exp_info.flags = flags;
 400         exp_info.priv = buf;
 401
 402         if (!buf->sgt_base)
 403                 buf->sgt_base = vb2_dc_get_base_sgt(buf);
 404
 405         if (WARN_ON(!buf->sgt_base))
 406                 return NULL;
 407
 408         dbuf = dma_buf_export(&exp_info);
 409         if (IS_ERR(dbuf))
 410                 return NULL;
 411
 412         /* dmabuf keeps reference to vb2 buffer */
 413         atomic_inc(&buf->refcount);
 414
 415         return dbuf;
 416 }
 417
 418 /*********************************************/
 419 /*       callbacks for USERPTR buffers       */
 420 /*********************************************/
 421
 422 static void vb2_dc_put_userptr(void *buf_priv)
 423 {
 424         struct vb2_dc_buf *buf = buf_priv;
 425         struct sg_table *sgt = buf->dma_sgt;
 426         int i;
 427         struct page **pages;
 428
 429         if (sgt) {
 430                 DEFINE_DMA_ATTRS(attrs);
 431
 432                 dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 433                 /*
 434                  * No need to sync to CPU, it's already synced to the CPU
 435                  * since the finish() memop will have been called before this.
 436                  */
 437                 dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 438                                    buf->dma_dir, &attrs);
 439                 pages = frame_vector_pages(buf->vec);
 440                 /* sgt should exist only if vector contains pages... */
 441                 BUG_ON(IS_ERR(pages));
 442                 for (i = 0; i < frame_vector_count(buf->vec); i++)
 443                         set_page_dirty_lock(pages[i]);
 444                 sg_free_table(sgt);
 445                 kfree(sgt);
 446         }
 447         vb2_destroy_framevec(buf->vec);
 448         kfree(buf);
 449 }
 450
 451 /*
 452  * For some kind of reserved memory there might be no struct page available,
 453  * so all that can be done to support such 'pages' is to try to convert
 454  * pfn to dma address or at the last resort just assume that
 455  * dma address == physical address (like it has been assumed in earlier version
 456  * of videobuf2-dma-contig
 457  */
 458
 459 #ifdef __arch_pfn_to_dma
 460 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 461 {
 462         return (dma_addr_t)__arch_pfn_to_dma(dev, pfn);
 463 }
 464 #elif defined(__pfn_to_bus)
 465 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 466 {
 467         return (dma_addr_t)__pfn_to_bus(pfn);
 468 }
 469 #elif defined(__pfn_to_phys)
 470 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 471 {
 472         return (dma_addr_t)__pfn_to_phys(pfn);
 473 }
 474 #else
 475 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 476 {
 477         /* really, we cannot do anything better at this point */
 478         return (dma_addr_t)(pfn) << PAGE_SHIFT;
 479 }
 480 #endif
 481
 482 static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 483         unsigned long size, enum dma_data_direction dma_dir)
 484 {
 485         struct vb2_dc_conf *conf = alloc_ctx;
 486         struct vb2_dc_buf *buf;
 487         struct frame_vector *vec;
 488         unsigned long offset;
 489         int n_pages, i;
 490         int ret = 0;
 491         struct sg_table *sgt;
 492         unsigned long contig_size;
 493         unsigned long dma_align = dma_get_cache_alignment();
 494         DEFINE_DMA_ATTRS(attrs);
 495
 496         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 497
 498         /* Only cache aligned DMA transfers are reliable */
 499         if (!IS_ALIGNED(vaddr | size, dma_align)) {
 500                 pr_debug("user data must be aligned to %lu bytes\n", dma_align);
 501                 return ERR_PTR(-EINVAL);
 502         }
 503
 504         if (!size) {
 505                 pr_debug("size is zero\n");
 506                 return ERR_PTR(-EINVAL);
 507         }
 508
 509         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 510         if (!buf)
 511                 return ERR_PTR(-ENOMEM);
 512
 513         buf->dev = conf->dev;
 514         buf->dma_dir = dma_dir;
 515
 516         offset = vaddr & ~PAGE_MASK;
 517         vec = vb2_create_framevec(vaddr, size, dma_dir == DMA_FROM_DEVICE);
 518         if (IS_ERR(vec)) {
 519                 ret = PTR_ERR(vec);
 520                 goto fail_buf;
 521         }
 522         buf->vec = vec;
 523         n_pages = frame_vector_count(vec);
 524         ret = frame_vector_to_pages(vec);
 525         if (ret < 0) {
 526                 unsigned long *nums = frame_vector_pfns(vec);
 527
 528                 /*
 529                  * Failed to convert to pages... Check the memory is physically
 530                  * contiguous and use direct mapping
 531                  */
 532                 for (i = 1; i < n_pages; i++)
 533                         if (nums[i-1] + 1 != nums[i])
 534                                 goto fail_pfnvec;
 535                 buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, nums[0]);
 536                 goto out;
 537         }
 538
 539         sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 540         if (!sgt) {
 541                 pr_err("failed to allocate sg table\n");
 542                 ret = -ENOMEM;
 543                 goto fail_pfnvec;
 544         }
 545
 546         ret = sg_alloc_table_from_pages(sgt, frame_vector_pages(vec), n_pages,
 547                 offset, size, GFP_KERNEL);
 548         if (ret) {
 549                 pr_err("failed to initialize sg table\n");
 550                 goto fail_sgt;
 551         }
 552
 553         /*
 554          * No need to sync to the device, this will happen later when the
 555          * prepare() memop is called.
 556          */
 557         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 558                                       buf->dma_dir, &attrs);
 559         if (sgt->nents <= 0) {
 560                 pr_err("failed to map scatterlist\n");
 561                 ret = -EIO;
 562                 goto fail_sgt_init;
 563         }
 564
 565         contig_size = vb2_dc_get_contiguous_size(sgt);
 566         if (contig_size < size) {
 567                 pr_err("contiguous mapping is too small %lu/%lu\n",
 568                         contig_size, size);
 569                 ret = -EFAULT;
 570                 goto fail_map_sg;
 571         }
 572
 573         buf->dma_addr = sg_dma_address(sgt->sgl);
 574         buf->dma_sgt = sgt;
 575 out:
 576         buf->size = size;
 577
 578         return buf;
 579
 580 fail_map_sg:
 581         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 582                            buf->dma_dir, &attrs);
 583
 584 fail_sgt_init:
 585         sg_free_table(sgt);
 586
 587 fail_sgt:
 588         kfree(sgt);
 589
 590 fail_pfnvec:
 591         vb2_destroy_framevec(vec);
 592
 593 fail_buf:
 594         kfree(buf);
 595
 596         return ERR_PTR(ret);
 597 }
 598
 599 /*********************************************/
 600 /*       callbacks for DMABUF buffers        */
 601 /*********************************************/
 602
 603 static int vb2_dc_map_dmabuf(void *mem_priv)
 604 {
 605         struct vb2_dc_buf *buf = mem_priv;
 606         struct sg_table *sgt;
 607         unsigned long contig_size;
 608
 609         if (WARN_ON(!buf->db_attach)) {
 610                 pr_err("trying to pin a non attached buffer\n");
 611                 return -EINVAL;
 612         }
 613
 614         if (WARN_ON(buf->dma_sgt)) {
 615                 pr_err("dmabuf buffer is already pinned\n");
 616                 return 0;
 617         }
 618
 619         /* get the associated scatterlist for this buffer */
 620         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 621         if (IS_ERR(sgt)) {
 622                 pr_err("Error getting dmabuf scatterlist\n");
 623                 return -EINVAL;
 624         }
 625
 626         /* checking if dmabuf is big enough to store contiguous chunk */
 627         contig_size = vb2_dc_get_contiguous_size(sgt);
 628         if (contig_size < buf->size) {
 629                 pr_err("contiguous chunk is too small %lu/%lu b\n",
 630                         contig_size, buf->size);
 631                 dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 632                 return -EFAULT;
 633         }
 634
 635         buf->dma_addr = sg_dma_address(sgt->sgl);
 636         buf->dma_sgt = sgt;
 637         buf->vaddr = NULL;
 638
 639         return 0;
 640 }
 641
 642 static void vb2_dc_unmap_dmabuf(void *mem_priv)
 643 {
 644         struct vb2_dc_buf *buf = mem_priv;
 645         struct sg_table *sgt = buf->dma_sgt;
 646
 647         if (WARN_ON(!buf->db_attach)) {
 648                 pr_err("trying to unpin a not attached buffer\n");
 649                 return;
 650         }
 651
 652         if (WARN_ON(!sgt)) {
 653                 pr_err("dmabuf buffer is already unpinned\n");
 654                 return;
 655         }
 656
 657         if (buf->vaddr) {
 658                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 659                 buf->vaddr = NULL;
 660         }
 661         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 662
 663         buf->dma_addr = 0;
 664         buf->dma_sgt = NULL;
 665 }
 666
 667 static void vb2_dc_detach_dmabuf(void *mem_priv)
 668 {
 669         struct vb2_dc_buf *buf = mem_priv;
 670
 671         /* if vb2 works correctly you should never detach mapped buffer */
 672         if (WARN_ON(buf->dma_addr))
 673                 vb2_dc_unmap_dmabuf(buf);
 674
 675         /* detach this attachment */
 676         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 677         kfree(buf);
 678 }
 679
 680 static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 681         unsigned long size, enum dma_data_direction dma_dir)
 682 {
 683         struct vb2_dc_conf *conf = alloc_ctx;
 684         struct vb2_dc_buf *buf;
 685         struct dma_buf_attachment *dba;
 686
 687         if (dbuf->size < size)
 688                 return ERR_PTR(-EFAULT);
 689
 690         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 691         if (!buf)
 692                 return ERR_PTR(-ENOMEM);
 693
 694         buf->dev = conf->dev;
 695         /* create attachment for the dmabuf with the user device */
 696         dba = dma_buf_attach(dbuf, buf->dev);
 697         if (IS_ERR(dba)) {
 698                 pr_err("failed to attach dmabuf\n");
 699                 kfree(buf);
 700                 return dba;
 701         }
 702
 703         buf->dma_dir = dma_dir;
 704         buf->size = size;
 705         buf->db_attach = dba;
 706
 707         return buf;
 708 }
 709
 710 /*********************************************/
 711 /*       DMA CONTIG exported functions       */
 712 /*********************************************/
 713
 714 const struct vb2_mem_ops vb2_dma_contig_memops = {
 715         .alloc          = vb2_dc_alloc,
 716         .put            = vb2_dc_put,
 717         .get_dmabuf     = vb2_dc_get_dmabuf,
 718         .cookie         = vb2_dc_cookie,
 719         .vaddr          = vb2_dc_vaddr,
 720         .mmap           = vb2_dc_mmap,
 721         .get_userptr    = vb2_dc_get_userptr,
 722         .put_userptr    = vb2_dc_put_userptr,
 723         .prepare        = vb2_dc_prepare,
 724         .finish         = vb2_dc_finish,
 725         .map_dmabuf     = vb2_dc_map_dmabuf,
 726         .unmap_dmabuf   = vb2_dc_unmap_dmabuf,
 727         .attach_dmabuf  = vb2_dc_attach_dmabuf,
 728         .detach_dmabuf  = vb2_dc_detach_dmabuf,
 729         .num_users      = vb2_dc_num_users,
 730 };
 731 EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
 732
 733 void *vb2_dma_contig_init_ctx(struct device *dev)
 734 {
 735         struct vb2_dc_conf *conf;
 736
 737         conf = kzalloc(sizeof *conf, GFP_KERNEL);
 738         if (!conf)
 739                 return ERR_PTR(-ENOMEM);
 740
 741         conf->dev = dev;
 742
 743         return conf;
 744 }
 745 EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);
 746
 747 void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
 748 {
 749         if (!IS_ERR_OR_NULL(alloc_ctx))
 750                 kfree(alloc_ctx);
 751 }
 752 EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
 753
 754 /**
 755  * vb2_dma_contig_set_max_seg_size() - configure DMA max segment size
 756  * @dev:        device for configuring DMA parameters
 757  * @size:       size of DMA max segment size to set
 758  *
 759  * To allow mapping the scatter-list into a single chunk in the DMA
 760  * address space, the device is required to have the DMA max segment
 761  * size parameter set to a value larger than the buffer size. Otherwise,
 762  * the DMA-mapping subsystem will split the mapping into max segment
 763  * size chunks. This function sets the DMA max segment size
 764  * parameter to let DMA-mapping map a buffer as a single chunk in DMA
 765  * address space.
 766  * This code assumes that the DMA-mapping subsystem will merge all
 767  * scatterlist segments if this is really possible (for example when
 768  * an IOMMU is available and enabled).
 769  * Ideally, this parameter should be set by the generic bus code, but it
 770  * is left with the default 64KiB value due to historical litmiations in
 771  * other subsystems (like limited USB host drivers) and there no good
 772  * place to set it to the proper value.
 773  * This function should be called from the drivers, which are known to
 774  * operate on platforms with IOMMU and provide access to shared buffers
 775  * (either USERPTR or DMABUF). This should be done before initializing
 776  * videobuf2 queue.
 777  */
 778 int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size)
 779 {
 780         if (!dev->dma_parms) {
 781                 dev->dma_parms = kzalloc(sizeof(dev->dma_parms), GFP_KERNEL);
 782                 if (!dev->dma_parms)
 783                         return -ENOMEM;
 784         }
 785         if (dma_get_max_seg_size(dev) < size)
 786                 return dma_set_max_seg_size(dev, size);
 787
 788         return 0;
 789 }
 790 EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);
 791
 792 /*
 793  * vb2_dma_contig_clear_max_seg_size() - release resources for DMA parameters
 794  * @dev:        device for configuring DMA parameters
 795  *
 796  * This function releases resources allocated to configure DMA parameters
 797  * (see vb2_dma_contig_set_max_seg_size() function). It should be called from
 798  * device drivers on driver remove.
 799  */
 800 void vb2_dma_contig_clear_max_seg_size(struct device *dev)
 801 {
 802         kfree(dev->dma_parms);
 803         dev->dma_parms = NULL;
 804 }
 805 EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size);
 806
 807 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 808 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 809 MODULE_LICENSE("GPL");