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         struct dma_attrs        attrs;
  27 };
  28
  29 struct vb2_dc_buf {
  30         struct device                   *dev;
  31         void                            *vaddr;
  32         unsigned long                   size;
  33         void                            *cookie;
  34         dma_addr_t                      dma_addr;
  35         struct dma_attrs                attrs;
  36         enum dma_data_direction         dma_dir;
  37         struct sg_table                 *dma_sgt;
  38         struct frame_vector             *vec;
  39
  40         /* MMAP related */
  41         struct vb2_vmarea_handler       handler;
  42         atomic_t                        refcount;
  43         struct sg_table                 *sgt_base;
  44
  45         /* DMABUF related */
  46         struct dma_buf_attachment       *db_attach;
  47 };
  48
  49 /*********************************************/
  50 /*        scatterlist table functions        */
  51 /*********************************************/
  52
  53 static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
  54 {
  55         struct scatterlist *s;
  56         dma_addr_t expected = sg_dma_address(sgt->sgl);
  57         unsigned int i;
  58         unsigned long size = 0;
  59
  60         for_each_sg(sgt->sgl, s, sgt->nents, i) {
  61                 if (sg_dma_address(s) != expected)
  62                         break;
  63                 expected = sg_dma_address(s) + sg_dma_len(s);
  64                 size += sg_dma_len(s);
  65         }
  66         return size;
  67 }
  68
  69 /*********************************************/
  70 /*         callbacks for all buffers         */
  71 /*********************************************/
  72
  73 static void *vb2_dc_cookie(void *buf_priv)
  74 {
  75         struct vb2_dc_buf *buf = buf_priv;
  76
  77         return &buf->dma_addr;
  78 }
  79
  80 static void *vb2_dc_vaddr(void *buf_priv)
  81 {
  82         struct vb2_dc_buf *buf = buf_priv;
  83
  84         if (!buf->vaddr && buf->db_attach)
  85                 buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
  86
  87         return buf->vaddr;
  88 }
  89
  90 static unsigned int vb2_dc_num_users(void *buf_priv)
  91 {
  92         struct vb2_dc_buf *buf = buf_priv;
  93
  94         return atomic_read(&buf->refcount);
  95 }
  96
  97 static void vb2_dc_prepare(void *buf_priv)
  98 {
  99         struct vb2_dc_buf *buf = buf_priv;
 100         struct sg_table *sgt = buf->dma_sgt;
 101
 102         /* DMABUF exporter will flush the cache for us */
 103         if (!sgt || buf->db_attach)
 104                 return;
 105
 106         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents,
 107                                buf->dma_dir);
 108 }
 109
 110 static void vb2_dc_finish(void *buf_priv)
 111 {
 112         struct vb2_dc_buf *buf = buf_priv;
 113         struct sg_table *sgt = buf->dma_sgt;
 114
 115         /* DMABUF exporter will flush the cache for us */
 116         if (!sgt || buf->db_attach)
 117                 return;
 118
 119         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 120 }
 121
 122 /*********************************************/
 123 /*        callbacks for MMAP buffers         */
 124 /*********************************************/
 125
 126 static void vb2_dc_put(void *buf_priv)
 127 {
 128         struct vb2_dc_buf *buf = buf_priv;
 129
 130         if (!atomic_dec_and_test(&buf->refcount))
 131                 return;
 132
 133         if (buf->sgt_base) {
 134                 sg_free_table(buf->sgt_base);
 135                 kfree(buf->sgt_base);
 136         }
 137         dma_free_attrs(buf->dev, buf->size, buf->cookie, buf->dma_addr,
 138                         &buf->attrs);
 139         put_device(buf->dev);
 140         kfree(buf);
 141 }
 142
 143 static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size,
 144                           enum dma_data_direction dma_dir, 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         buf->attrs = conf->attrs;
 155         buf->cookie = dma_alloc_attrs(dev, size, &buf->dma_addr,
 156                                         GFP_KERNEL | gfp_flags, &buf->attrs);
 157         if (!buf->cookie) {
 158                 dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
 159                 kfree(buf);
 160                 return ERR_PTR(-ENOMEM);
 161         }
 162
 163         if (!dma_get_attr(DMA_ATTR_NO_KERNEL_MAPPING, &buf->attrs))
 164                 buf->vaddr = buf->cookie;
 165
 166         /* Prevent the device from being released while the buffer is used */
 167         buf->dev = get_device(dev);
 168         buf->size = size;
 169         buf->dma_dir = dma_dir;
 170
 171         buf->handler.refcount = &buf->refcount;
 172         buf->handler.put = vb2_dc_put;
 173         buf->handler.arg = buf;
 174
 175         atomic_inc(&buf->refcount);
 176
 177         return buf;
 178 }
 179
 180 static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
 181 {
 182         struct vb2_dc_buf *buf = buf_priv;
 183         int ret;
 184
 185         if (!buf) {
 186                 printk(KERN_ERR "No buffer to map\n");
 187                 return -EINVAL;
 188         }
 189
 190         /*
 191          * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
 192          * map whole buffer
 193          */
 194         vma->vm_pgoff = 0;
 195
 196         ret = dma_mmap_attrs(buf->dev, vma, buf->cookie,
 197                 buf->dma_addr, buf->size, &buf->attrs);
 198
 199         if (ret) {
 200                 pr_err("Remapping memory failed, error: %d\n", ret);
 201                 return ret;
 202         }
 203
 204         vma->vm_flags           |= VM_DONTEXPAND | VM_DONTDUMP;
 205         vma->vm_private_data    = &buf->handler;
 206         vma->vm_ops             = &vb2_common_vm_ops;
 207
 208         vma->vm_ops->open(vma);
 209
 210         pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
 211                 __func__, (unsigned long)buf->dma_addr, vma->vm_start,
 212                 buf->size);
 213
 214         return 0;
 215 }
 216
 217 /*********************************************/
 218 /*         DMABUF ops for exporters          */
 219 /*********************************************/
 220
 221 struct vb2_dc_attachment {
 222         struct sg_table sgt;
 223         enum dma_data_direction dma_dir;
 224 };
 225
 226 static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 227         struct dma_buf_attachment *dbuf_attach)
 228 {
 229         struct vb2_dc_attachment *attach;
 230         unsigned int i;
 231         struct scatterlist *rd, *wr;
 232         struct sg_table *sgt;
 233         struct vb2_dc_buf *buf = dbuf->priv;
 234         int ret;
 235
 236         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 237         if (!attach)
 238                 return -ENOMEM;
 239
 240         sgt = &attach->sgt;
 241         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 242          * map the same scatter list to multiple attachments at the same time.
 243          */
 244         ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
 245         if (ret) {
 246                 kfree(attach);
 247                 return -ENOMEM;
 248         }
 249
 250         rd = buf->sgt_base->sgl;
 251         wr = sgt->sgl;
 252         for (i = 0; i < sgt->orig_nents; ++i) {
 253                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 254                 rd = sg_next(rd);
 255                 wr = sg_next(wr);
 256         }
 257
 258         attach->dma_dir = DMA_NONE;
 259         dbuf_attach->priv = attach;
 260
 261         return 0;
 262 }
 263
 264 static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
 265         struct dma_buf_attachment *db_attach)
 266 {
 267         struct vb2_dc_attachment *attach = db_attach->priv;
 268         struct sg_table *sgt;
 269
 270         if (!attach)
 271                 return;
 272
 273         sgt = &attach->sgt;
 274
 275         /* release the scatterlist cache */
 276         if (attach->dma_dir != DMA_NONE)
 277                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 278                         attach->dma_dir);
 279         sg_free_table(sgt);
 280         kfree(attach);
 281         db_attach->priv = NULL;
 282 }
 283
 284 static struct sg_table *vb2_dc_dmabuf_ops_map(
 285         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 286 {
 287         struct vb2_dc_attachment *attach = db_attach->priv;
 288         /* stealing dmabuf mutex to serialize map/unmap operations */
 289         struct mutex *lock = &db_attach->dmabuf->lock;
 290         struct sg_table *sgt;
 291
 292         mutex_lock(lock);
 293
 294         sgt = &attach->sgt;
 295         /* return previously mapped sg table */
 296         if (attach->dma_dir == dma_dir) {
 297                 mutex_unlock(lock);
 298                 return sgt;
 299         }
 300
 301         /* release any previous cache */
 302         if (attach->dma_dir != DMA_NONE) {
 303                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 304                         attach->dma_dir);
 305                 attach->dma_dir = DMA_NONE;
 306         }
 307
 308         /* mapping to the client with new direction */
 309         sgt->nents = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 310                                 dma_dir);
 311         if (!sgt->nents) {
 312                 pr_err("failed to map scatterlist\n");
 313                 mutex_unlock(lock);
 314                 return ERR_PTR(-EIO);
 315         }
 316
 317         attach->dma_dir = dma_dir;
 318
 319         mutex_unlock(lock);
 320
 321         return sgt;
 322 }
 323
 324 static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 325         struct sg_table *sgt, enum dma_data_direction dma_dir)
 326 {
 327         /* nothing to be done here */
 328 }
 329
 330 static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
 331 {
 332         /* drop reference obtained in vb2_dc_get_dmabuf */
 333         vb2_dc_put(dbuf->priv);
 334 }
 335
 336 static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 337 {
 338         struct vb2_dc_buf *buf = dbuf->priv;
 339
 340         return buf->vaddr ? buf->vaddr + pgnum * PAGE_SIZE : NULL;
 341 }
 342
 343 static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
 344 {
 345         struct vb2_dc_buf *buf = dbuf->priv;
 346
 347         return buf->vaddr;
 348 }
 349
 350 static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
 351         struct vm_area_struct *vma)
 352 {
 353         return vb2_dc_mmap(dbuf->priv, vma);
 354 }
 355
 356 static struct dma_buf_ops vb2_dc_dmabuf_ops = {
 357         .attach = vb2_dc_dmabuf_ops_attach,
 358         .detach = vb2_dc_dmabuf_ops_detach,
 359         .map_dma_buf = vb2_dc_dmabuf_ops_map,
 360         .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
 361         .kmap = vb2_dc_dmabuf_ops_kmap,
 362         .kmap_atomic = vb2_dc_dmabuf_ops_kmap,
 363         .vmap = vb2_dc_dmabuf_ops_vmap,
 364         .mmap = vb2_dc_dmabuf_ops_mmap,
 365         .release = vb2_dc_dmabuf_ops_release,
 366 };
 367
 368 static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
 369 {
 370         int ret;
 371         struct sg_table *sgt;
 372
 373         sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
 374         if (!sgt) {
 375                 dev_err(buf->dev, "failed to alloc sg table\n");
 376                 return NULL;
 377         }
 378
 379         ret = dma_get_sgtable_attrs(buf->dev, sgt, buf->cookie, buf->dma_addr,
 380                 buf->size, &buf->attrs);
 381         if (ret < 0) {
 382                 dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
 383                 kfree(sgt);
 384                 return NULL;
 385         }
 386
 387         return sgt;
 388 }
 389
 390 static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
 391 {
 392         struct vb2_dc_buf *buf = buf_priv;
 393         struct dma_buf *dbuf;
 394         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 395
 396         exp_info.ops = &vb2_dc_dmabuf_ops;
 397         exp_info.size = buf->size;
 398         exp_info.flags = flags;
 399         exp_info.priv = buf;
 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(&exp_info);
 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 void vb2_dc_put_userptr(void *buf_priv)
 422 {
 423         struct vb2_dc_buf *buf = buf_priv;
 424         struct sg_table *sgt = buf->dma_sgt;
 425         int i;
 426         struct page **pages;
 427
 428         if (sgt) {
 429                 DEFINE_DMA_ATTRS(attrs);
 430
 431                 dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 432                 /*
 433                  * No need to sync to CPU, it's already synced to the CPU
 434                  * since the finish() memop will have been called before this.
 435                  */
 436                 dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 437                                    buf->dma_dir, &attrs);
 438                 pages = frame_vector_pages(buf->vec);
 439                 /* sgt should exist only if vector contains pages... */
 440                 BUG_ON(IS_ERR(pages));
 441                 for (i = 0; i < frame_vector_count(buf->vec); i++)
 442                         set_page_dirty_lock(pages[i]);
 443                 sg_free_table(sgt);
 444                 kfree(sgt);
 445         }
 446         vb2_destroy_framevec(buf->vec);
 447         kfree(buf);
 448 }
 449
 450 /*
 451  * For some kind of reserved memory there might be no struct page available,
 452  * so all that can be done to support such 'pages' is to try to convert
 453  * pfn to dma address or at the last resort just assume that
 454  * dma address == physical address (like it has been assumed in earlier version
 455  * of videobuf2-dma-contig
 456  */
 457
 458 #ifdef __arch_pfn_to_dma
 459 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 460 {
 461         return (dma_addr_t)__arch_pfn_to_dma(dev, pfn);
 462 }
 463 #elif defined(__pfn_to_bus)
 464 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 465 {
 466         return (dma_addr_t)__pfn_to_bus(pfn);
 467 }
 468 #elif defined(__pfn_to_phys)
 469 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 470 {
 471         return (dma_addr_t)__pfn_to_phys(pfn);
 472 }
 473 #else
 474 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 475 {
 476         /* really, we cannot do anything better at this point */
 477         return (dma_addr_t)(pfn) << PAGE_SHIFT;
 478 }
 479 #endif
 480
 481 static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 482         unsigned long size, enum dma_data_direction dma_dir)
 483 {
 484         struct vb2_dc_conf *conf = alloc_ctx;
 485         struct vb2_dc_buf *buf;
 486         struct frame_vector *vec;
 487         unsigned long offset;
 488         int n_pages, i;
 489         int ret = 0;
 490         struct sg_table *sgt;
 491         unsigned long contig_size;
 492         unsigned long dma_align = dma_get_cache_alignment();
 493         DEFINE_DMA_ATTRS(attrs);
 494
 495         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 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 = dma_dir;
 514
 515         offset = vaddr & ~PAGE_MASK;
 516         vec = vb2_create_framevec(vaddr, size, dma_dir == DMA_FROM_DEVICE);
 517         if (IS_ERR(vec)) {
 518                 ret = PTR_ERR(vec);
 519                 goto fail_buf;
 520         }
 521         buf->vec = vec;
 522         n_pages = frame_vector_count(vec);
 523         ret = frame_vector_to_pages(vec);
 524         if (ret < 0) {
 525                 unsigned long *nums = frame_vector_pfns(vec);
 526
 527                 /*
 528                  * Failed to convert to pages... Check the memory is physically
 529                  * contiguous and use direct mapping
 530                  */
 531                 for (i = 1; i < n_pages; i++)
 532                         if (nums[i-1] + 1 != nums[i])
 533                                 goto fail_pfnvec;
 534                 buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, nums[0]);
 535                 goto out;
 536         }
 537
 538         sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 539         if (!sgt) {
 540                 pr_err("failed to allocate sg table\n");
 541                 ret = -ENOMEM;
 542                 goto fail_pfnvec;
 543         }
 544
 545         ret = sg_alloc_table_from_pages(sgt, frame_vector_pages(vec), n_pages,
 546                 offset, size, GFP_KERNEL);
 547         if (ret) {
 548                 pr_err("failed to initialize sg table\n");
 549                 goto fail_sgt;
 550         }
 551
 552         /*
 553          * No need to sync to the device, this will happen later when the
 554          * prepare() memop is called.
 555          */
 556         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 557                                       buf->dma_dir, &attrs);
 558         if (sgt->nents <= 0) {
 559                 pr_err("failed to map scatterlist\n");
 560                 ret = -EIO;
 561                 goto fail_sgt_init;
 562         }
 563
 564         contig_size = vb2_dc_get_contiguous_size(sgt);
 565         if (contig_size < size) {
 566                 pr_err("contiguous mapping is too small %lu/%lu\n",
 567                         contig_size, size);
 568                 ret = -EFAULT;
 569                 goto fail_map_sg;
 570         }
 571
 572         buf->dma_addr = sg_dma_address(sgt->sgl);
 573         buf->dma_sgt = sgt;
 574 out:
 575         buf->size = size;
 576
 577         return buf;
 578
 579 fail_map_sg:
 580         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 581                            buf->dma_dir, &attrs);
 582
 583 fail_sgt_init:
 584         sg_free_table(sgt);
 585
 586 fail_sgt:
 587         kfree(sgt);
 588
 589 fail_pfnvec:
 590         vb2_destroy_framevec(vec);
 591
 592 fail_buf:
 593         kfree(buf);
 594
 595         return ERR_PTR(ret);
 596 }
 597
 598 /*********************************************/
 599 /*       callbacks for DMABUF buffers        */
 600 /*********************************************/
 601
 602 static int vb2_dc_map_dmabuf(void *mem_priv)
 603 {
 604         struct vb2_dc_buf *buf = mem_priv;
 605         struct sg_table *sgt;
 606         unsigned long contig_size;
 607
 608         if (WARN_ON(!buf->db_attach)) {
 609                 pr_err("trying to pin a non attached buffer\n");
 610                 return -EINVAL;
 611         }
 612
 613         if (WARN_ON(buf->dma_sgt)) {
 614                 pr_err("dmabuf buffer is already pinned\n");
 615                 return 0;
 616         }
 617
 618         /* get the associated scatterlist for this buffer */
 619         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 620         if (IS_ERR(sgt)) {
 621                 pr_err("Error getting dmabuf scatterlist\n");
 622                 return -EINVAL;
 623         }
 624
 625         /* checking if dmabuf is big enough to store contiguous chunk */
 626         contig_size = vb2_dc_get_contiguous_size(sgt);
 627         if (contig_size < buf->size) {
 628                 pr_err("contiguous chunk is too small %lu/%lu b\n",
 629                         contig_size, buf->size);
 630                 dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 631                 return -EFAULT;
 632         }
 633
 634         buf->dma_addr = sg_dma_address(sgt->sgl);
 635         buf->dma_sgt = sgt;
 636         buf->vaddr = NULL;
 637
 638         return 0;
 639 }
 640
 641 static void vb2_dc_unmap_dmabuf(void *mem_priv)
 642 {
 643         struct vb2_dc_buf *buf = mem_priv;
 644         struct sg_table *sgt = buf->dma_sgt;
 645
 646         if (WARN_ON(!buf->db_attach)) {
 647                 pr_err("trying to unpin a not attached buffer\n");
 648                 return;
 649         }
 650
 651         if (WARN_ON(!sgt)) {
 652                 pr_err("dmabuf buffer is already unpinned\n");
 653                 return;
 654         }
 655
 656         if (buf->vaddr) {
 657                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 658                 buf->vaddr = NULL;
 659         }
 660         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 661
 662         buf->dma_addr = 0;
 663         buf->dma_sgt = NULL;
 664 }
 665
 666 static void vb2_dc_detach_dmabuf(void *mem_priv)
 667 {
 668         struct vb2_dc_buf *buf = mem_priv;
 669
 670         /* if vb2 works correctly you should never detach mapped buffer */
 671         if (WARN_ON(buf->dma_addr))
 672                 vb2_dc_unmap_dmabuf(buf);
 673
 674         /* detach this attachment */
 675         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 676         kfree(buf);
 677 }
 678
 679 static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 680         unsigned long size, enum dma_data_direction dma_dir)
 681 {
 682         struct vb2_dc_conf *conf = alloc_ctx;
 683         struct vb2_dc_buf *buf;
 684         struct dma_buf_attachment *dba;
 685
 686         if (dbuf->size < size)
 687                 return ERR_PTR(-EFAULT);
 688
 689         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 690         if (!buf)
 691                 return ERR_PTR(-ENOMEM);
 692
 693         buf->dev = conf->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 void *vb2_dma_contig_init_ctx_attrs(struct device *dev,
 733                                     struct dma_attrs *attrs)
 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         if (attrs)
 743                 conf->attrs = *attrs;
 744
 745         return conf;
 746 }
 747 EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx_attrs);
 748
 749 void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
 750 {
 751         if (!IS_ERR_OR_NULL(alloc_ctx))
 752                 kfree(alloc_ctx);
 753 }
 754 EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
 755
 756 /**
 757  * vb2_dma_contig_set_max_seg_size() - configure DMA max segment size
 758  * @dev:        device for configuring DMA parameters
 759  * @size:       size of DMA max segment size to set
 760  *
 761  * To allow mapping the scatter-list into a single chunk in the DMA
 762  * address space, the device is required to have the DMA max segment
 763  * size parameter set to a value larger than the buffer size. Otherwise,
 764  * the DMA-mapping subsystem will split the mapping into max segment
 765  * size chunks. This function sets the DMA max segment size
 766  * parameter to let DMA-mapping map a buffer as a single chunk in DMA
 767  * address space.
 768  * This code assumes that the DMA-mapping subsystem will merge all
 769  * scatterlist segments if this is really possible (for example when
 770  * an IOMMU is available and enabled).
 771  * Ideally, this parameter should be set by the generic bus code, but it
 772  * is left with the default 64KiB value due to historical litmiations in
 773  * other subsystems (like limited USB host drivers) and there no good
 774  * place to set it to the proper value.
 775  * This function should be called from the drivers, which are known to
 776  * operate on platforms with IOMMU and provide access to shared buffers
 777  * (either USERPTR or DMABUF). This should be done before initializing
 778  * videobuf2 queue.
 779  */
 780 int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size)
 781 {
 782         if (!dev->dma_parms) {
 783                 dev->dma_parms = kzalloc(sizeof(dev->dma_parms), GFP_KERNEL);
 784                 if (!dev->dma_parms)
 785                         return -ENOMEM;
 786         }
 787         if (dma_get_max_seg_size(dev) < size)
 788                 return dma_set_max_seg_size(dev, size);
 789
 790         return 0;
 791 }
 792 EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);
 793
 794 /*
 795  * vb2_dma_contig_clear_max_seg_size() - release resources for DMA parameters
 796  * @dev:        device for configuring DMA parameters
 797  *
 798  * This function releases resources allocated to configure DMA parameters
 799  * (see vb2_dma_contig_set_max_seg_size() function). It should be called from
 800  * device drivers on driver remove.
 801  */
 802 void vb2_dma_contig_clear_max_seg_size(struct device *dev)
 803 {
 804         kfree(dev->dma_parms);
 805         dev->dma_parms = NULL;
 806 }
 807 EXPORT_SYMBOL_GPL(vb2_dma_contig_clear_max_seg_size);
 808
 809 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 810 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 811 MODULE_LICENSE("GPL");