drivers/media/common/videobuf2/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/refcount.h>
  16 #include <linux/scatterlist.h>
  17 #include <linux/sched.h>
  18 #include <linux/slab.h>
  19 #include <linux/dma-mapping.h>
  20
  21 #include <media/videobuf2-v4l2.h>
  22 #include <media/videobuf2-dma-contig.h>
  23 #include <media/videobuf2-memops.h>
  24
  25 struct vb2_dc_buf {
  26         struct device                   *dev;
  27         void                            *vaddr;
  28         unsigned long                   size;
  29         void                            *cookie;
  30         dma_addr_t                      dma_addr;
  31         unsigned long                   attrs;
  32         enum dma_data_direction         dma_dir;
  33         struct sg_table                 *dma_sgt;
  34         struct frame_vector             *vec;
  35
  36         /* MMAP related */
  37         struct vb2_vmarea_handler       handler;
  38         refcount_t                      refcount;
  39         struct sg_table                 *sgt_base;
  40
  41         /* DMABUF related */
  42         struct dma_buf_attachment       *db_attach;
  43 };
  44
  45 /*********************************************/
  46 /*        scatterlist table functions        */
  47 /*********************************************/
  48
  49 static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
  50 {
  51         struct scatterlist *s;
  52         dma_addr_t expected = sg_dma_address(sgt->sgl);
  53         unsigned int i;
  54         unsigned long size = 0;
  55
  56         for_each_sg(sgt->sgl, s, sgt->nents, i) {
  57                 if (sg_dma_address(s) != expected)
  58                         break;
  59                 expected = sg_dma_address(s) + sg_dma_len(s);
  60                 size += sg_dma_len(s);
  61         }
  62         return size;
  63 }
  64
  65 /*********************************************/
  66 /*         callbacks for all buffers         */
  67 /*********************************************/
  68
  69 static void *vb2_dc_cookie(void *buf_priv)
  70 {
  71         struct vb2_dc_buf *buf = buf_priv;
  72
  73         return &buf->dma_addr;
  74 }
  75
  76 static void *vb2_dc_vaddr(void *buf_priv)
  77 {
  78         struct vb2_dc_buf *buf = buf_priv;
  79
  80         if (!buf->vaddr && buf->db_attach)
  81                 buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
  82
  83         return buf->vaddr;
  84 }
  85
  86 static unsigned int vb2_dc_num_users(void *buf_priv)
  87 {
  88         struct vb2_dc_buf *buf = buf_priv;
  89
  90         return refcount_read(&buf->refcount);
  91 }
  92
  93 static void vb2_dc_prepare(void *buf_priv)
  94 {
  95         struct vb2_dc_buf *buf = buf_priv;
  96         struct sg_table *sgt = buf->dma_sgt;
  97
  98         /* DMABUF exporter will flush the cache for us */
  99         if (!sgt || buf->db_attach)
 100                 return;
 101
 102         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
 103                                buf->dma_dir);
 104 }
 105
 106 static void vb2_dc_finish(void *buf_priv)
 107 {
 108         struct vb2_dc_buf *buf = buf_priv;
 109         struct sg_table *sgt = buf->dma_sgt;
 110
 111         /* DMABUF exporter will flush the cache for us */
 112         if (!sgt || buf->db_attach)
 113                 return;
 114
 115         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 116 }
 117
 118 /*********************************************/
 119 /*        callbacks for MMAP buffers         */
 120 /*********************************************/
 121
 122 static void vb2_dc_put(void *buf_priv)
 123 {
 124         struct vb2_dc_buf *buf = buf_priv;
 125
 126         if (!refcount_dec_and_test(&buf->refcount))
 127                 return;
 128
 129         if (buf->sgt_base) {
 130                 sg_free_table(buf->sgt_base);
 131                 kfree(buf->sgt_base);
 132         }
 133         dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr,
 134                        buf->attrs);
 135         put_device(buf->dev);
 136         kfree(buf);
 137 }
 138
 139 static void *vb2_dc_alloc(struct device *dev, unsigned long attrs,
 140                           unsigned long size, enum dma_data_direction dma_dir,
 141                           gfp_t gfp_flags)
 142 {
 143         struct vb2_dc_buf *buf;
 144
 145         if (WARN_ON(!dev))
 146                 return ERR_PTR(-EINVAL);
 147
 148         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 149         if (!buf)
 150                 return ERR_PTR(-ENOMEM);
 151
 152         if (attrs)
 153                 buf->attrs = attrs;
 154         buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr,
 155                                         GFP_KERNEL | gfp_flags, buf->attrs);
 156         if (!buf->cookie) {
 157                 dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
 158                 kfree(buf);
 159                 return ERR_PTR(-ENOMEM);
 160         }
 161
 162         if ((buf->attrs & DMA_ATTR_NO_KERNEL_MAPPING) == 0)
 163                 buf->vaddr = buf->cookie;
 164
 165         /* Prevent the device from being released while the buffer is used */
 166         buf->dev = get_device(dev);
 167         buf->size = size;
 168         buf->dma_dir = dma_dir;
 169
 170         buf->handler.refcount = &buf->refcount;
 171         buf->handler.put = vb2_dc_put;
 172         buf->handler.arg = buf;
 173
 174         refcount_set(&buf->refcount, 1);
 175
 176         return buf;
 177 }
 178
 179 static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
 180 {
 181         struct vb2_dc_buf *buf = buf_priv;
 182         int ret;
 183
 184         if (!buf) {
 185                 printk(KERN_ERR "No buffer to map\n");
 186                 return -EINVAL;
 187         }
 188
 189         /*
 190          * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
 191          * map whole buffer
 192          */
 193         vma->vm_pgoff = 0;
 194
 195         ret = dma_mmap_attrs(buf->dev, vma, buf->cookie,
 196                 buf->dma_addr, buf->size, buf->attrs);
 197
 198         if (ret) {
 199                 pr_err("Remapping memory failed, error: %d\n", ret);
 200                 return ret;
 201         }
 202
 203         vma->vm_flags           |= VM_DONTEXPAND | VM_DONTDUMP;
 204         vma->vm_private_data    = &buf->handler;
 205         vma->vm_ops             = &vb2_common_vm_ops;
 206
 207         vma->vm_ops->open(vma);
 208
 209         pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
 210                 __func__, (unsigned long)buf->dma_addr, vma->vm_start,
 211                 buf->size);
 212
 213         return 0;
 214 }
 215
 216 /*********************************************/
 217 /*         DMABUF ops for exporters          */
 218 /*********************************************/
 219
 220 struct vb2_dc_attachment {
 221         struct sg_table sgt;
 222         enum dma_data_direction dma_dir;
 223 };
 224
 225 static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 226         struct dma_buf_attachment *dbuf_attach)
 227 {
 228         struct vb2_dc_attachment *attach;
 229         unsigned int i;
 230         struct scatterlist *rd, *wr;
 231         struct sg_table *sgt;
 232         struct vb2_dc_buf *buf = dbuf->priv;
 233         int ret;
 234
 235         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 236         if (!attach)
 237                 return -ENOMEM;
 238
 239         sgt = &attach->sgt;
 240         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 241          * map the same scatter list to multiple attachments at the same time.
 242          */
 243         ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
 244         if (ret) {
 245                 kfree(attach);
 246                 return -ENOMEM;
 247         }
 248
 249         rd = buf->sgt_base->sgl;
 250         wr = sgt->sgl;
 251         for (i = 0; i < sgt->orig_nents; ++i) {
 252                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 253                 rd = sg_next(rd);
 254                 wr = sg_next(wr);
 255         }
 256
 257         attach->dma_dir = DMA_NONE;
 258         dbuf_attach->priv = attach;
 259
 260         return 0;
 261 }
 262
 263 static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
 264         struct dma_buf_attachment *db_attach)
 265 {
 266         struct vb2_dc_attachment *attach = db_attach->priv;
 267         struct sg_table *sgt;
 268
 269         if (!attach)
 270                 return;
 271
 272         sgt = &attach->sgt;
 273
 274         /* release the scatterlist cache */
 275         if (attach->dma_dir != DMA_NONE)
 276                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 277                         attach->dma_dir);
 278         sg_free_table(sgt);
 279         kfree(attach);
 280         db_attach->priv = NULL;
 281 }
 282
 283 static struct sg_table *vb2_dc_dmabuf_ops_map(
 284         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 285 {
 286         struct vb2_dc_attachment *attach = db_attach->priv;
 287         /* stealing dmabuf mutex to serialize map/unmap operations */
 288         struct mutex *lock = &db_attach->dmabuf->lock;
 289         struct sg_table *sgt;
 290
 291         mutex_lock(lock);
 292
 293         sgt = &attach->sgt;
 294         /* return previously mapped sg table */
 295         if (attach->dma_dir == dma_dir) {
 296                 mutex_unlock(lock);
 297                 return sgt;
 298         }
 299
 300         /* release any previous cache */
 301         if (attach->dma_dir != DMA_NONE) {
 302                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 303                         attach->dma_dir);
 304                 attach->dma_dir = DMA_NONE;
 305         }
 306
 307         /* mapping to the client with new direction */
 308         sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 309                                 dma_dir);
 310         if (!sgt->nents) {
 311                 pr_err("failed to map scatterlist\n");
 312                 mutex_unlock(lock);
 313                 return ERR_PTR(-EIO);
 314         }
 315
 316         attach->dma_dir = dma_dir;
 317
 318         mutex_unlock(lock);
 319
 320         return sgt;
 321 }
 322
 323 static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 324         struct sg_table *sgt, enum dma_data_direction dma_dir)
 325 {
 326         /* nothing to be done here */
 327 }
 328
 329 static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
 330 {
 331         /* drop reference obtained in vb2_dc_get_dmabuf */
 332         vb2_dc_put(dbuf->priv);
 333 }
 334
 335 static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 336 {
 337         struct vb2_dc_buf *buf = dbuf->priv;
 338
 339         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 340 }
 341
 342 static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
 343 {
 344         struct vb2_dc_buf *buf = dbuf->priv;
 345
 346         return buf->vaddr;
 347 }
 348
 349 static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
 350         struct vm_area_struct *vma)
 351 {
 352         return vb2_dc_mmap(dbuf->priv, vma);
 353 }
 354
 355 static const struct dma_buf_ops vb2_dc_dmabuf_ops = {
 356         .attach = vb2_dc_dmabuf_ops_attach,
 357         .detach = vb2_dc_dmabuf_ops_detach,
 358         .map_dma_buf = vb2_dc_dmabuf_ops_map,
 359         .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
 360         .map = vb2_dc_dmabuf_ops_kmap,
 361         .map_atomic = vb2_dc_dmabuf_ops_kmap,
 362         .vmap = vb2_dc_dmabuf_ops_vmap,
 363         .mmap = vb2_dc_dmabuf_ops_mmap,
 364         .release = vb2_dc_dmabuf_ops_release,
 365 };
 366
 367 static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
 368 {
 369         int ret;
 370         struct sg_table *sgt;
 371
 372         sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
 373         if (!sgt) {
 374                 dev_err(buf->dev, "failed to alloc sg table\n");
 375                 return NULL;
 376         }
 377
 378         ret = dma_get_sgtable_attrs(buf->dev, sgt, buf->cookie, buf->dma_addr,
 379                 buf->size, buf->attrs);
 380         if (ret < 0) {
 381                 dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
 382                 kfree(sgt);
 383                 return NULL;
 384         }
 385
 386         return sgt;
 387 }
 388
 389 static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
 390 {
 391         struct vb2_dc_buf *buf = buf_priv;
 392         struct dma_buf *dbuf;
 393         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 394
 395         exp_info.ops = &vb2_dc_dmabuf_ops;
 396         exp_info.size = buf->size;
 397         exp_info.flags = flags;
 398         exp_info.priv = buf;
 399
 400         if (!buf->sgt_base)
 401                 buf->sgt_base = vb2_dc_get_base_sgt(buf);
 402
 403         if (WARN_ON(!buf->sgt_base))
 404                 return NULL;
 405
 406         dbuf = dma_buf_export(&exp_info);
 407         if (IS_ERR(dbuf))
 408                 return NULL;
 409
 410         /* dmabuf keeps reference to vb2 buffer */
 411         refcount_inc(&buf->refcount);
 412
 413         return dbuf;
 414 }
 415
 416 /*********************************************/
 417 /*       callbacks for USERPTR buffers       */
 418 /*********************************************/
 419
 420 static void vb2_dc_put_userptr(void *buf_priv)
 421 {
 422         struct vb2_dc_buf *buf = buf_priv;
 423         struct sg_table *sgt = buf->dma_sgt;
 424         int i;
 425         struct page **pages;
 426
 427         if (sgt) {
 428                 /*
 429                  * No need to sync to CPU, it's already synced to the CPU
 430                  * since the finish() memop will have been called before this.
 431                  */
 432                 dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 433                                    buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 434                 pages = frame_vector_pages(buf->vec);
 435                 /* sgt should exist only if vector contains pages... */
 436                 BUG_ON(IS_ERR(pages));
 437                 if (buf->dma_dir == DMA_FROM_DEVICE ||
 438                     buf->dma_dir == DMA_BIDIRECTIONAL)
 439                         for (i = 0; i < frame_vector_count(buf->vec); i++)
 440                                 set_page_dirty_lock(pages[i]);
 441                 sg_free_table(sgt);
 442                 kfree(sgt);
 443         }
 444         vb2_destroy_framevec(buf->vec);
 445         kfree(buf);
 446 }
 447
 448 /*
 449  * For some kind of reserved memory there might be no struct page available,
 450  * so all that can be done to support such 'pages' is to try to convert
 451  * pfn to dma address or at the last resort just assume that
 452  * dma address == physical address (like it has been assumed in earlier version
 453  * of videobuf2-dma-contig
 454  */
 455
 456 #ifdef __arch_pfn_to_dma
 457 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 458 {
 459         return (dma_addr_t)__arch_pfn_to_dma(dev, pfn);
 460 }
 461 #elif defined(__pfn_to_bus)
 462 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 463 {
 464         return (dma_addr_t)__pfn_to_bus(pfn);
 465 }
 466 #elif defined(__pfn_to_phys)
 467 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 468 {
 469         return (dma_addr_t)__pfn_to_phys(pfn);
 470 }
 471 #else
 472 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 473 {
 474         /* really, we cannot do anything better at this point */
 475         return (dma_addr_t)(pfn) << PAGE_SHIFT;
 476 }
 477 #endif
 478
 479 static void *vb2_dc_get_userptr(struct device *dev, unsigned long vaddr,
 480         unsigned long size, enum dma_data_direction dma_dir)
 481 {
 482         struct vb2_dc_buf *buf;
 483         struct frame_vector *vec;
 484         unsigned int offset;
 485         int n_pages, i;
 486         int ret = 0;
 487         struct sg_table *sgt;
 488         unsigned long contig_size;
 489         unsigned long dma_align = dma_get_cache_alignment();
 490
 491         /* Only cache aligned DMA transfers are reliable */
 492         if (!IS_ALIGNED(vaddr | size, dma_align)) {
 493                 pr_debug("user data must be aligned to %lu bytes\n", dma_align);
 494                 return ERR_PTR(-EINVAL);
 495         }
 496
 497         if (!size) {
 498                 pr_debug("size is zero\n");
 499                 return ERR_PTR(-EINVAL);
 500         }
 501
 502         if (WARN_ON(!dev))
 503                 return ERR_PTR(-EINVAL);
 504
 505         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 506         if (!buf)
 507                 return ERR_PTR(-ENOMEM);
 508
 509         buf->dev = dev;
 510         buf->dma_dir = dma_dir;
 511
 512         offset = lower_32_bits(offset_in_page(vaddr));
 513         vec = vb2_create_framevec(vaddr, size, dma_dir == DMA_FROM_DEVICE ||
 514                                                dma_dir == DMA_BIDIRECTIONAL);
 515         if (IS_ERR(vec)) {
 516                 ret = PTR_ERR(vec);
 517                 goto fail_buf;
 518         }
 519         buf->vec = vec;
 520         n_pages = frame_vector_count(vec);
 521         ret = frame_vector_to_pages(vec);
 522         if (ret < 0) {
 523                 unsigned long *nums = frame_vector_pfns(vec);
 524
 525                 /*
 526                  * Failed to convert to pages... Check the memory is physically
 527                  * contiguous and use direct mapping
 528                  */
 529                 for (i = 1; i < n_pages; i++)
 530                         if (nums[i-1] + 1 != nums[i])
 531                                 goto fail_pfnvec;
 532                 buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, nums[0]);
 533                 goto out;
 534         }
 535
 536         sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 537         if (!sgt) {
 538                 pr_err("failed to allocate sg table\n");
 539                 ret = -ENOMEM;
 540                 goto fail_pfnvec;
 541         }
 542
 543         ret = sg_alloc_table_from_pages(sgt, frame_vector_pages(vec), n_pages,
 544                 offset, size, GFP_KERNEL);
 545         if (ret) {
 546                 pr_err("failed to initialize sg table\n");
 547                 goto fail_sgt;
 548         }
 549
 550         /*
 551          * No need to sync to the device, this will happen later when the
 552          * prepare() memop is called.
 553          */
 554         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 555                                       buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 556         if (sgt->nents <= 0) {
 557                 pr_err("failed to map scatterlist\n");
 558                 ret = -EIO;
 559                 goto fail_sgt_init;
 560         }
 561
 562         contig_size = vb2_dc_get_contiguous_size(sgt);
 563         if (contig_size < size) {
 564                 pr_err("contiguous mapping is too small %lu/%lu\n",
 565                         contig_size, size);
 566                 ret = -EFAULT;
 567                 goto fail_map_sg;
 568         }
 569
 570         buf->dma_addr = sg_dma_address(sgt->sgl);
 571         buf->dma_sgt = sgt;
 572 out:
 573         buf->size = size;
 574
 575         return buf;
 576
 577 fail_map_sg:
 578         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 579                            buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
 580
 581 fail_sgt_init:
 582         sg_free_table(sgt);
 583
 584 fail_sgt:
 585         kfree(sgt);
 586
 587 fail_pfnvec:
 588         vb2_destroy_framevec(vec);
 589
 590 fail_buf:
 591         kfree(buf);
 592
 593         return ERR_PTR(ret);
 594 }
 595
 596 /*********************************************/
 597 /*       callbacks for DMABUF buffers        */
 598 /*********************************************/
 599
 600 static int vb2_dc_map_dmabuf(void *mem_priv)
 601 {
 602         struct vb2_dc_buf *buf = mem_priv;
 603         struct sg_table *sgt;
 604         unsigned long contig_size;
 605
 606         if (WARN_ON(!buf->db_attach)) {
 607                 pr_err("trying to pin a non attached buffer\n");
 608                 return -EINVAL;
 609         }
 610
 611         if (WARN_ON(buf->dma_sgt)) {
 612                 pr_err("dmabuf buffer is already pinned\n");
 613                 return 0;
 614         }
 615
 616         /* get the associated scatterlist for this buffer */
 617         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 618         if (IS_ERR(sgt)) {
 619                 pr_err("Error getting dmabuf scatterlist\n");
 620                 return -EINVAL;
 621         }
 622
 623         /* checking if dmabuf is big enough to store contiguous chunk */
 624         contig_size = vb2_dc_get_contiguous_size(sgt);
 625         if (contig_size < buf->size) {
 626                 pr_err("contiguous chunk is too small %lu/%lu b\n",
 627                         contig_size, buf->size);
 628                 dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 629                 return -EFAULT;
 630         }
 631
 632         buf->dma_addr = sg_dma_address(sgt->sgl);
 633         buf->dma_sgt = sgt;
 634         buf->vaddr = NULL;
 635
 636         return 0;
 637 }
 638
 639 static void vb2_dc_unmap_dmabuf(void *mem_priv)
 640 {
 641         struct vb2_dc_buf *buf = mem_priv;
 642         struct sg_table *sgt = buf->dma_sgt;
 643
 644         if (WARN_ON(!buf->db_attach)) {
 645                 pr_err("trying to unpin a not attached buffer\n");
 646                 return;
 647         }
 648
 649         if (WARN_ON(!sgt)) {
 650                 pr_err("dmabuf buffer is already unpinned\n");
 651                 return;
 652         }
 653
 654         if (buf->vaddr) {
 655                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 656                 buf->vaddr = NULL;
 657         }
 658         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 659
 660         buf->dma_addr = 0;
 661         buf->dma_sgt = NULL;
 662 }
 663
 664 static void vb2_dc_detach_dmabuf(void *mem_priv)
 665 {
 666         struct vb2_dc_buf *buf = mem_priv;
 667
 668         /* if vb2 works correctly you should never detach mapped buffer */
 669         if (WARN_ON(buf->dma_addr))
 670                 vb2_dc_unmap_dmabuf(buf);
 671
 672         /* detach this attachment */
 673         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 674         kfree(buf);
 675 }
 676
 677 static void *vb2_dc_attach_dmabuf(struct device *dev, struct dma_buf *dbuf,
 678         unsigned long size, enum dma_data_direction dma_dir)
 679 {
 680         struct vb2_dc_buf *buf;
 681         struct dma_buf_attachment *dba;
 682
 683         if (dbuf->size < size)
 684                 return ERR_PTR(-EFAULT);
 685
 686         if (WARN_ON(!dev))
 687                 return ERR_PTR(-EINVAL);
 688
 689         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 690         if (!buf)
 691                 return ERR_PTR(-ENOMEM);
 692
 693         buf->dev = dev;
 694         /* create attachment for the dmabuf with the user device */
 695         dba = dma_buf_attach(dbuf, buf->dev);
 696         if (IS_ERR(dba)) {
 697                 pr_err("failed to attach dmabuf\n");
 698                 kfree(buf);
 699                 return dba;
 700         }
 701
 702         buf->dma_dir = dma_dir;
 703         buf->size = size;
 704         buf->db_attach = dba;
 705
 706         return buf;
 707 }
 708
 709 /*********************************************/
 710 /*       DMA CONTIG exported functions       */
 711 /*********************************************/
 712
 713 const struct vb2_mem_ops vb2_dma_contig_memops = {
 714         .alloc          = vb2_dc_alloc,
 715         .put            = vb2_dc_put,
 716         .get_dmabuf     = vb2_dc_get_dmabuf,
 717         .cookie         = vb2_dc_cookie,
 718         .vaddr          = vb2_dc_vaddr,
 719         .mmap           = vb2_dc_mmap,
 720         .get_userptr    = vb2_dc_get_userptr,
 721         .put_userptr    = vb2_dc_put_userptr,
 722         .prepare        = vb2_dc_prepare,
 723         .finish         = vb2_dc_finish,
 724         .map_dmabuf     = vb2_dc_map_dmabuf,
 725         .unmap_dmabuf   = vb2_dc_unmap_dmabuf,
 726         .attach_dmabuf  = vb2_dc_attach_dmabuf,
 727         .detach_dmabuf  = vb2_dc_detach_dmabuf,
 728         .num_users      = vb2_dc_num_users,
 729 };
 730 EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
 731
 732 /**
 733  * vb2_dma_contig_set_max_seg_size() - configure DMA max segment size
 734  * @dev:        device for configuring DMA parameters
 735  * @size:       size of DMA max segment size to set
 736  *
 737  * To allow mapping the scatter-list into a single chunk in the DMA
 738  * address space, the device is required to have the DMA max segment
 739  * size parameter set to a value larger than the buffer size. Otherwise,
 740  * the DMA-mapping subsystem will split the mapping into max segment
 741  * size chunks. This function sets the DMA max segment size
 742  * parameter to let DMA-mapping map a buffer as a single chunk in DMA
 743  * address space.
 744  * This code assumes that the DMA-mapping subsystem will merge all
 745  * scatterlist segments if this is really possible (for example when
 746  * an IOMMU is available and enabled).
 747  * Ideally, this parameter should be set by the generic bus code, but it
 748  * is left with the default 64KiB value due to historical litmiations in
 749  * other subsystems (like limited USB host drivers) and there no good
 750  * place to set it to the proper value.
 751  * This function should be called from the drivers, which are known to
 752  * operate on platforms with IOMMU and provide access to shared buffers
 753  * (either USERPTR or DMABUF). This should be done before initializing
 754  * videobuf2 queue.
 755  */
 756 int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size)
 757 {
 758         if (!dev->dma_parms) {
 759                 dev->dma_parms = kzalloc(sizeof(*dev->dma_parms), GFP_KERNEL);
 760                 if (!dev->dma_parms)
 761                         return -ENOMEM;
 762         }
 763         if (dma_get_max_seg_size(dev) < size)
 764                 return dma_set_max_seg_size(dev, size);
 765
 766         return 0;
 767 }
 768 EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);
 769
 770 /*
 771  * vb2_dma_contig_clear_max_seg_size() - release resources for DMA parameters
 772  * @dev:        device for configuring DMA parameters
 773  *
 774  * This function releases resources allocated to configure DMA parameters
 775  * (see vb2_dma_contig_set_max_seg_size() function). It should be called from
 776  * device drivers on driver remove.
 777  */
 778 void vb2_dma_contig_clear_max_seg_size(struct device *dev)
 779 {
 780         kfree(dev->dma_parms);
 781         dev->dma_parms = NULL;
 782 }
 783 EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size);
 784
 785 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 786 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 787 MODULE_LICENSE("GPL");