kernel/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         if (!buf->vaddr && buf->db_attach)
 102                 buf->vaddr = dma_buf_vmap(buf->db_attach->dmabuf);
 103
 104         return buf->vaddr;
 105 }
 106
 107 static unsigned int vb2_dc_num_users(void *buf_priv)
 108 {
 109         struct vb2_dc_buf *buf = buf_priv;
 110
 111         return atomic_read(&buf->refcount);
 112 }
 113
 114 static void vb2_dc_prepare(void *buf_priv)
 115 {
 116         struct vb2_dc_buf *buf = buf_priv;
 117         struct sg_table *sgt = buf->dma_sgt;
 118
 119         /* DMABUF exporter will flush the cache for us */
 120         if (!sgt || buf->db_attach)
 121                 return;
 122
 123         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 124 }
 125
 126 static void vb2_dc_finish(void *buf_priv)
 127 {
 128         struct vb2_dc_buf *buf = buf_priv;
 129         struct sg_table *sgt = buf->dma_sgt;
 130
 131         /* DMABUF exporter will flush the cache for us */
 132         if (!sgt || buf->db_attach)
 133                 return;
 134
 135         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 136 }
 137
 138 /*********************************************/
 139 /*        callbacks for MMAP buffers         */
 140 /*********************************************/
 141
 142 static void vb2_dc_put(void *buf_priv)
 143 {
 144         struct vb2_dc_buf *buf = buf_priv;
 145
 146         if (!atomic_dec_and_test(&buf->refcount))
 147                 return;
 148
 149         if (buf->sgt_base) {
 150                 sg_free_table(buf->sgt_base);
 151                 kfree(buf->sgt_base);
 152         }
 153         dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
 154         put_device(buf->dev);
 155         kfree(buf);
 156 }
 157
 158 static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size,
 159                           enum dma_data_direction dma_dir, gfp_t gfp_flags)
 160 {
 161         struct vb2_dc_conf *conf = alloc_ctx;
 162         struct device *dev = conf->dev;
 163         struct vb2_dc_buf *buf;
 164
 165         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 166         if (!buf)
 167                 return ERR_PTR(-ENOMEM);
 168
 169         buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr,
 170                                                 GFP_KERNEL | gfp_flags);
 171         if (!buf->vaddr) {
 172                 dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
 173                 kfree(buf);
 174                 return ERR_PTR(-ENOMEM);
 175         }
 176
 177         /* Prevent the device from being released while the buffer is used */
 178         buf->dev = get_device(dev);
 179         buf->size = size;
 180         buf->dma_dir = dma_dir;
 181
 182         buf->handler.refcount = &buf->refcount;
 183         buf->handler.put = vb2_dc_put;
 184         buf->handler.arg = buf;
 185
 186         atomic_inc(&buf->refcount);
 187
 188         return buf;
 189 }
 190
 191 static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
 192 {
 193         struct vb2_dc_buf *buf = buf_priv;
 194         int ret;
 195
 196         if (!buf) {
 197                 printk(KERN_ERR "No buffer to map\n");
 198                 return -EINVAL;
 199         }
 200
 201         /*
 202          * dma_mmap_* uses vm_pgoff as in-buffer offset, but we want to
 203          * map whole buffer
 204          */
 205         vma->vm_pgoff = 0;
 206
 207         ret = dma_mmap_coherent(buf->dev, vma, buf->vaddr,
 208                 buf->dma_addr, buf->size);
 209
 210         if (ret) {
 211                 pr_err("Remapping memory failed, error: %d\n", ret);
 212                 return ret;
 213         }
 214
 215         vma->vm_flags           |= VM_DONTEXPAND | VM_DONTDUMP;
 216         vma->vm_private_data    = &buf->handler;
 217         vma->vm_ops             = &vb2_common_vm_ops;
 218
 219         vma->vm_ops->open(vma);
 220
 221         pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %ld\n",
 222                 __func__, (unsigned long)buf->dma_addr, vma->vm_start,
 223                 buf->size);
 224
 225         return 0;
 226 }
 227
 228 /*********************************************/
 229 /*         DMABUF ops for exporters          */
 230 /*********************************************/
 231
 232 struct vb2_dc_attachment {
 233         struct sg_table sgt;
 234         enum dma_data_direction dma_dir;
 235 };
 236
 237 static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf, struct device *dev,
 238         struct dma_buf_attachment *dbuf_attach)
 239 {
 240         struct vb2_dc_attachment *attach;
 241         unsigned int i;
 242         struct scatterlist *rd, *wr;
 243         struct sg_table *sgt;
 244         struct vb2_dc_buf *buf = dbuf->priv;
 245         int ret;
 246
 247         attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 248         if (!attach)
 249                 return -ENOMEM;
 250
 251         sgt = &attach->sgt;
 252         /* Copy the buf->base_sgt scatter list to the attachment, as we can't
 253          * map the same scatter list to multiple attachments at the same time.
 254          */
 255         ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
 256         if (ret) {
 257                 kfree(attach);
 258                 return -ENOMEM;
 259         }
 260
 261         rd = buf->sgt_base->sgl;
 262         wr = sgt->sgl;
 263         for (i = 0; i < sgt->orig_nents; ++i) {
 264                 sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
 265                 rd = sg_next(rd);
 266                 wr = sg_next(wr);
 267         }
 268
 269         attach->dma_dir = DMA_NONE;
 270         dbuf_attach->priv = attach;
 271
 272         return 0;
 273 }
 274
 275 static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
 276         struct dma_buf_attachment *db_attach)
 277 {
 278         struct vb2_dc_attachment *attach = db_attach->priv;
 279         struct sg_table *sgt;
 280
 281         if (!attach)
 282                 return;
 283
 284         sgt = &attach->sgt;
 285
 286         /* release the scatterlist cache */
 287         if (attach->dma_dir != DMA_NONE)
 288                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 289                         attach->dma_dir);
 290         sg_free_table(sgt);
 291         kfree(attach);
 292         db_attach->priv = NULL;
 293 }
 294
 295 static struct sg_table *vb2_dc_dmabuf_ops_map(
 296         struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
 297 {
 298         struct vb2_dc_attachment *attach = db_attach->priv;
 299         /* stealing dmabuf mutex to serialize map/unmap operations */
 300         struct mutex *lock = &db_attach->dmabuf->lock;
 301         struct sg_table *sgt;
 302         int ret;
 303
 304         mutex_lock(lock);
 305
 306         sgt = &attach->sgt;
 307         /* return previously mapped sg table */
 308         if (attach->dma_dir == dma_dir) {
 309                 mutex_unlock(lock);
 310                 return sgt;
 311         }
 312
 313         /* release any previous cache */
 314         if (attach->dma_dir != DMA_NONE) {
 315                 dma_unmap_sg(db_attach->dev, sgt->sgl, sgt->orig_nents,
 316                         attach->dma_dir);
 317                 attach->dma_dir = DMA_NONE;
 318         }
 319
 320         /* mapping to the client with new direction */
 321         ret = dma_map_sg(db_attach->dev, sgt->sgl, sgt->orig_nents, dma_dir);
 322         if (ret <= 0) {
 323                 pr_err("failed to map scatterlist\n");
 324                 mutex_unlock(lock);
 325                 return ERR_PTR(-EIO);
 326         }
 327
 328         attach->dma_dir = dma_dir;
 329
 330         mutex_unlock(lock);
 331
 332         return sgt;
 333 }
 334
 335 static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
 336         struct sg_table *sgt, enum dma_data_direction dma_dir)
 337 {
 338         /* nothing to be done here */
 339 }
 340
 341 static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
 342 {
 343         /* drop reference obtained in vb2_dc_get_dmabuf */
 344         vb2_dc_put(dbuf->priv);
 345 }
 346
 347 static void *vb2_dc_dmabuf_ops_kmap(struct dma_buf *dbuf, unsigned long pgnum)
 348 {
 349         struct vb2_dc_buf *buf = dbuf->priv;
 350
 351         return buf->vaddr + pgnum * PAGE_SIZE;
 352 }
 353
 354 static void *vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf)
 355 {
 356         struct vb2_dc_buf *buf = dbuf->priv;
 357
 358         return buf->vaddr;
 359 }
 360
 361 static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
 362         struct vm_area_struct *vma)
 363 {
 364         return vb2_dc_mmap(dbuf->priv, vma);
 365 }
 366
 367 static struct dma_buf_ops vb2_dc_dmabuf_ops = {
 368         .attach = vb2_dc_dmabuf_ops_attach,
 369         .detach = vb2_dc_dmabuf_ops_detach,
 370         .map_dma_buf = vb2_dc_dmabuf_ops_map,
 371         .unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
 372         .kmap = vb2_dc_dmabuf_ops_kmap,
 373         .kmap_atomic = vb2_dc_dmabuf_ops_kmap,
 374         .vmap = vb2_dc_dmabuf_ops_vmap,
 375         .mmap = vb2_dc_dmabuf_ops_mmap,
 376         .release = vb2_dc_dmabuf_ops_release,
 377 };
 378
 379 static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
 380 {
 381         int ret;
 382         struct sg_table *sgt;
 383
 384         sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
 385         if (!sgt) {
 386                 dev_err(buf->dev, "failed to alloc sg table\n");
 387                 return NULL;
 388         }
 389
 390         ret = dma_get_sgtable(buf->dev, sgt, buf->vaddr, buf->dma_addr,
 391                 buf->size);
 392         if (ret < 0) {
 393                 dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
 394                 kfree(sgt);
 395                 return NULL;
 396         }
 397
 398         return sgt;
 399 }
 400
 401 static struct dma_buf *vb2_dc_get_dmabuf(void *buf_priv, unsigned long flags)
 402 {
 403         struct vb2_dc_buf *buf = buf_priv;
 404         struct dma_buf *dbuf;
 405         DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 406
 407         exp_info.ops = &vb2_dc_dmabuf_ops;
 408         exp_info.size = buf->size;
 409         exp_info.flags = flags;
 410         exp_info.priv = buf;
 411
 412         if (!buf->sgt_base)
 413                 buf->sgt_base = vb2_dc_get_base_sgt(buf);
 414
 415         if (WARN_ON(!buf->sgt_base))
 416                 return NULL;
 417
 418         dbuf = dma_buf_export(&exp_info);
 419         if (IS_ERR(dbuf))
 420                 return NULL;
 421
 422         /* dmabuf keeps reference to vb2 buffer */
 423         atomic_inc(&buf->refcount);
 424
 425         return dbuf;
 426 }
 427
 428 /*********************************************/
 429 /*       callbacks for USERPTR buffers       */
 430 /*********************************************/
 431
 432 static inline int vma_is_io(struct vm_area_struct *vma)
 433 {
 434         return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
 435 }
 436
 437 static int vb2_dc_get_user_pfn(unsigned long start, int n_pages,
 438         struct vm_area_struct *vma, unsigned long *res)
 439 {
 440         unsigned long pfn, start_pfn, prev_pfn;
 441         unsigned int i;
 442         int ret;
 443
 444         if (!vma_is_io(vma))
 445                 return -EFAULT;
 446
 447         ret = follow_pfn(vma, start, &pfn);
 448         if (ret)
 449                 return ret;
 450
 451         start_pfn = pfn;
 452         start += PAGE_SIZE;
 453
 454         for (i = 1; i < n_pages; ++i, start += PAGE_SIZE) {
 455                 prev_pfn = pfn;
 456                 ret = follow_pfn(vma, start, &pfn);
 457
 458                 if (ret) {
 459                         pr_err("no page for address %lu\n", start);
 460                         return ret;
 461                 }
 462                 if (pfn != prev_pfn + 1)
 463                         return -EINVAL;
 464         }
 465
 466         *res = start_pfn;
 467         return 0;
 468 }
 469
 470 static int vb2_dc_get_user_pages(unsigned long start, struct page **pages,
 471         int n_pages, struct vm_area_struct *vma,
 472         enum dma_data_direction dma_dir)
 473 {
 474         if (vma_is_io(vma)) {
 475                 unsigned int i;
 476
 477                 for (i = 0; i < n_pages; ++i, start += PAGE_SIZE) {
 478                         unsigned long pfn;
 479                         int ret = follow_pfn(vma, start, &pfn);
 480
 481                         if (!pfn_valid(pfn))
 482                                 return -EINVAL;
 483
 484                         if (ret) {
 485                                 pr_err("no page for address %lu\n", start);
 486                                 return ret;
 487                         }
 488                         pages[i] = pfn_to_page(pfn);
 489                 }
 490         } else {
 491                 int n;
 492
 493                 n = get_user_pages(current, current->mm, start & PAGE_MASK,
 494                         n_pages, dma_dir == DMA_FROM_DEVICE, 1, pages, NULL);
 495                 /* negative error means that no page was pinned */
 496                 n = max(n, 0);
 497                 if (n != n_pages) {
 498                         pr_err("got only %d of %d user pages\n", n, n_pages);
 499                         while (n)
 500                                 put_page(pages[--n]);
 501                         return -EFAULT;
 502                 }
 503         }
 504
 505         return 0;
 506 }
 507
 508 static void vb2_dc_put_dirty_page(struct page *page)
 509 {
 510         set_page_dirty_lock(page);
 511         put_page(page);
 512 }
 513
 514 static void vb2_dc_put_userptr(void *buf_priv)
 515 {
 516         struct vb2_dc_buf *buf = buf_priv;
 517         struct sg_table *sgt = buf->dma_sgt;
 518
 519         if (sgt) {
 520                 DEFINE_DMA_ATTRS(attrs);
 521
 522                 dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 523                 /*
 524                  * No need to sync to CPU, it's already synced to the CPU
 525                  * since the finish() memop will have been called before this.
 526                  */
 527                 dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 528                                    buf->dma_dir, &attrs);
 529                 if (!vma_is_io(buf->vma))
 530                         vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);
 531
 532                 sg_free_table(sgt);
 533                 kfree(sgt);
 534         }
 535         vb2_put_vma(buf->vma);
 536         kfree(buf);
 537 }
 538
 539 /*
 540  * For some kind of reserved memory there might be no struct page available,
 541  * so all that can be done to support such 'pages' is to try to convert
 542  * pfn to dma address or at the last resort just assume that
 543  * dma address == physical address (like it has been assumed in earlier version
 544  * of videobuf2-dma-contig
 545  */
 546
 547 #ifdef __arch_pfn_to_dma
 548 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 549 {
 550         return (dma_addr_t)__arch_pfn_to_dma(dev, pfn);
 551 }
 552 #elif defined(__pfn_to_bus)
 553 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 554 {
 555         return (dma_addr_t)__pfn_to_bus(pfn);
 556 }
 557 #elif defined(__pfn_to_phys)
 558 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 559 {
 560         return (dma_addr_t)__pfn_to_phys(pfn);
 561 }
 562 #else
 563 static inline dma_addr_t vb2_dc_pfn_to_dma(struct device *dev, unsigned long pfn)
 564 {
 565         /* really, we cannot do anything better at this point */
 566         return (dma_addr_t)(pfn) << PAGE_SHIFT;
 567 }
 568 #endif
 569
 570 static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 571         unsigned long size, enum dma_data_direction dma_dir)
 572 {
 573         struct vb2_dc_conf *conf = alloc_ctx;
 574         struct vb2_dc_buf *buf;
 575         unsigned long start;
 576         unsigned long end;
 577         unsigned long offset;
 578         struct page **pages;
 579         int n_pages;
 580         int ret = 0;
 581         struct vm_area_struct *vma;
 582         struct sg_table *sgt;
 583         unsigned long contig_size;
 584         unsigned long dma_align = dma_get_cache_alignment();
 585         DEFINE_DMA_ATTRS(attrs);
 586
 587         dma_set_attr(DMA_ATTR_SKIP_CPU_SYNC, &attrs);
 588
 589         /* Only cache aligned DMA transfers are reliable */
 590         if (!IS_ALIGNED(vaddr | size, dma_align)) {
 591                 pr_debug("user data must be aligned to %lu bytes\n", dma_align);
 592                 return ERR_PTR(-EINVAL);
 593         }
 594
 595         if (!size) {
 596                 pr_debug("size is zero\n");
 597                 return ERR_PTR(-EINVAL);
 598         }
 599
 600         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 601         if (!buf)
 602                 return ERR_PTR(-ENOMEM);
 603
 604         buf->dev = conf->dev;
 605         buf->dma_dir = dma_dir;
 606
 607         start = vaddr & PAGE_MASK;
 608         offset = vaddr & ~PAGE_MASK;
 609         end = PAGE_ALIGN(vaddr + size);
 610         n_pages = (end - start) >> PAGE_SHIFT;
 611
 612         pages = kmalloc(n_pages * sizeof(pages[0]), GFP_KERNEL);
 613         if (!pages) {
 614                 ret = -ENOMEM;
 615                 pr_err("failed to allocate pages table\n");
 616                 goto fail_buf;
 617         }
 618
 619         /* current->mm->mmap_sem is taken by videobuf2 core */
 620         vma = find_vma(current->mm, vaddr);
 621         if (!vma) {
 622                 pr_err("no vma for address %lu\n", vaddr);
 623                 ret = -EFAULT;
 624                 goto fail_pages;
 625         }
 626
 627         if (vma->vm_end < vaddr + size) {
 628                 pr_err("vma at %lu is too small for %lu bytes\n", vaddr, size);
 629                 ret = -EFAULT;
 630                 goto fail_pages;
 631         }
 632
 633         buf->vma = vb2_get_vma(vma);
 634         if (!buf->vma) {
 635                 pr_err("failed to copy vma\n");
 636                 ret = -ENOMEM;
 637                 goto fail_pages;
 638         }
 639
 640         /* extract page list from userspace mapping */
 641         ret = vb2_dc_get_user_pages(start, pages, n_pages, vma, dma_dir);
 642         if (ret) {
 643                 unsigned long pfn;
 644                 if (vb2_dc_get_user_pfn(start, n_pages, vma, &pfn) == 0) {
 645                         buf->dma_addr = vb2_dc_pfn_to_dma(buf->dev, pfn);
 646                         buf->size = size;
 647                         kfree(pages);
 648                         return buf;
 649                 }
 650
 651                 pr_err("failed to get user pages\n");
 652                 goto fail_vma;
 653         }
 654
 655         sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 656         if (!sgt) {
 657                 pr_err("failed to allocate sg table\n");
 658                 ret = -ENOMEM;
 659                 goto fail_get_user_pages;
 660         }
 661
 662         ret = sg_alloc_table_from_pages(sgt, pages, n_pages,
 663                 offset, size, GFP_KERNEL);
 664         if (ret) {
 665                 pr_err("failed to initialize sg table\n");
 666                 goto fail_sgt;
 667         }
 668
 669         /* pages are no longer needed */
 670         kfree(pages);
 671         pages = NULL;
 672
 673         /*
 674          * No need to sync to the device, this will happen later when the
 675          * prepare() memop is called.
 676          */
 677         sgt->nents = dma_map_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 678                                       buf->dma_dir, &attrs);
 679         if (sgt->nents <= 0) {
 680                 pr_err("failed to map scatterlist\n");
 681                 ret = -EIO;
 682                 goto fail_sgt_init;
 683         }
 684
 685         contig_size = vb2_dc_get_contiguous_size(sgt);
 686         if (contig_size < size) {
 687                 pr_err("contiguous mapping is too small %lu/%lu\n",
 688                         contig_size, size);
 689                 ret = -EFAULT;
 690                 goto fail_map_sg;
 691         }
 692
 693         buf->dma_addr = sg_dma_address(sgt->sgl);
 694         buf->size = size;
 695         buf->dma_sgt = sgt;
 696
 697         return buf;
 698
 699 fail_map_sg:
 700         dma_unmap_sg_attrs(buf->dev, sgt->sgl, sgt->orig_nents,
 701                            buf->dma_dir, &attrs);
 702
 703 fail_sgt_init:
 704         if (!vma_is_io(buf->vma))
 705                 vb2_dc_sgt_foreach_page(sgt, put_page);
 706         sg_free_table(sgt);
 707
 708 fail_sgt:
 709         kfree(sgt);
 710
 711 fail_get_user_pages:
 712         if (pages && !vma_is_io(buf->vma))
 713                 while (n_pages)
 714                         put_page(pages[--n_pages]);
 715
 716 fail_vma:
 717         vb2_put_vma(buf->vma);
 718
 719 fail_pages:
 720         kfree(pages); /* kfree is NULL-proof */
 721
 722 fail_buf:
 723         kfree(buf);
 724
 725         return ERR_PTR(ret);
 726 }
 727
 728 /*********************************************/
 729 /*       callbacks for DMABUF buffers        */
 730 /*********************************************/
 731
 732 static int vb2_dc_map_dmabuf(void *mem_priv)
 733 {
 734         struct vb2_dc_buf *buf = mem_priv;
 735         struct sg_table *sgt;
 736         unsigned long contig_size;
 737
 738         if (WARN_ON(!buf->db_attach)) {
 739                 pr_err("trying to pin a non attached buffer\n");
 740                 return -EINVAL;
 741         }
 742
 743         if (WARN_ON(buf->dma_sgt)) {
 744                 pr_err("dmabuf buffer is already pinned\n");
 745                 return 0;
 746         }
 747
 748         /* get the associated scatterlist for this buffer */
 749         sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
 750         if (IS_ERR(sgt)) {
 751                 pr_err("Error getting dmabuf scatterlist\n");
 752                 return -EINVAL;
 753         }
 754
 755         /* checking if dmabuf is big enough to store contiguous chunk */
 756         contig_size = vb2_dc_get_contiguous_size(sgt);
 757         if (contig_size < buf->size) {
 758                 pr_err("contiguous chunk is too small %lu/%lu b\n",
 759                         contig_size, buf->size);
 760                 dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 761                 return -EFAULT;
 762         }
 763
 764         buf->dma_addr = sg_dma_address(sgt->sgl);
 765         buf->dma_sgt = sgt;
 766         buf->vaddr = NULL;
 767
 768         return 0;
 769 }
 770
 771 static void vb2_dc_unmap_dmabuf(void *mem_priv)
 772 {
 773         struct vb2_dc_buf *buf = mem_priv;
 774         struct sg_table *sgt = buf->dma_sgt;
 775
 776         if (WARN_ON(!buf->db_attach)) {
 777                 pr_err("trying to unpin a not attached buffer\n");
 778                 return;
 779         }
 780
 781         if (WARN_ON(!sgt)) {
 782                 pr_err("dmabuf buffer is already unpinned\n");
 783                 return;
 784         }
 785
 786         if (buf->vaddr) {
 787                 dma_buf_vunmap(buf->db_attach->dmabuf, buf->vaddr);
 788                 buf->vaddr = NULL;
 789         }
 790         dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
 791
 792         buf->dma_addr = 0;
 793         buf->dma_sgt = NULL;
 794 }
 795
 796 static void vb2_dc_detach_dmabuf(void *mem_priv)
 797 {
 798         struct vb2_dc_buf *buf = mem_priv;
 799
 800         /* if vb2 works correctly you should never detach mapped buffer */
 801         if (WARN_ON(buf->dma_addr))
 802                 vb2_dc_unmap_dmabuf(buf);
 803
 804         /* detach this attachment */
 805         dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
 806         kfree(buf);
 807 }
 808
 809 static void *vb2_dc_attach_dmabuf(void *alloc_ctx, struct dma_buf *dbuf,
 810         unsigned long size, enum dma_data_direction dma_dir)
 811 {
 812         struct vb2_dc_conf *conf = alloc_ctx;
 813         struct vb2_dc_buf *buf;
 814         struct dma_buf_attachment *dba;
 815
 816         if (dbuf->size < size)
 817                 return ERR_PTR(-EFAULT);
 818
 819         buf = kzalloc(sizeof(*buf), GFP_KERNEL);
 820         if (!buf)
 821                 return ERR_PTR(-ENOMEM);
 822
 823         buf->dev = conf->dev;
 824         /* create attachment for the dmabuf with the user device */
 825         dba = dma_buf_attach(dbuf, buf->dev);
 826         if (IS_ERR(dba)) {
 827                 pr_err("failed to attach dmabuf\n");
 828                 kfree(buf);
 829                 return dba;
 830         }
 831
 832         buf->dma_dir = dma_dir;
 833         buf->size = size;
 834         buf->db_attach = dba;
 835
 836         return buf;
 837 }
 838
 839 /*********************************************/
 840 /*       DMA CONTIG exported functions       */
 841 /*********************************************/
 842
 843 const struct vb2_mem_ops vb2_dma_contig_memops = {
 844         .alloc          = vb2_dc_alloc,
 845         .put            = vb2_dc_put,
 846         .get_dmabuf     = vb2_dc_get_dmabuf,
 847         .cookie         = vb2_dc_cookie,
 848         .vaddr          = vb2_dc_vaddr,
 849         .mmap           = vb2_dc_mmap,
 850         .get_userptr    = vb2_dc_get_userptr,
 851         .put_userptr    = vb2_dc_put_userptr,
 852         .prepare        = vb2_dc_prepare,
 853         .finish         = vb2_dc_finish,
 854         .map_dmabuf     = vb2_dc_map_dmabuf,
 855         .unmap_dmabuf   = vb2_dc_unmap_dmabuf,
 856         .attach_dmabuf  = vb2_dc_attach_dmabuf,
 857         .detach_dmabuf  = vb2_dc_detach_dmabuf,
 858         .num_users      = vb2_dc_num_users,
 859 };
 860 EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
 861
 862 void *vb2_dma_contig_init_ctx(struct device *dev)
 863 {
 864         struct vb2_dc_conf *conf;
 865
 866         conf = kzalloc(sizeof *conf, GFP_KERNEL);
 867         if (!conf)
 868                 return ERR_PTR(-ENOMEM);
 869
 870         conf->dev = dev;
 871
 872         return conf;
 873 }
 874 EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);
 875
 876 void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
 877 {
 878         if (!IS_ERR_OR_NULL(alloc_ctx))
 879                 kfree(alloc_ctx);
 880 }
 881 EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
 882
 883 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 884 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 885 MODULE_LICENSE("GPL");