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