drivers/media/video/videobuf-dma-sg.c

   1 /*
   2  * helper functions for SG DMA video4linux capture buffers
   3  *
   4  * The functions expect the hardware being able to scatter gather
   5  * (i.e. the buffers are not linear in physical memory, but fragmented
   6  * into PAGE_SIZE chunks).  They also assume the driver does not need
   7  * to touch the video data.
   8  *
   9  * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
  10  *
  11  * Highly based on video-buf written originally by:
  12  * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
  13  * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
  14  * (c) 2006 Ted Walther and John Sokol
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 2
  19  */
  20
  21 #include <linux/init.h>
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/sched.h>
  25 #include <linux/slab.h>
  26 #include <linux/interrupt.h>
  27
  28 #include <linux/dma-mapping.h>
  29 #include <linux/vmalloc.h>
  30 #include <linux/pagemap.h>
  31 #include <linux/scatterlist.h>
  32 #include <asm/page.h>
  33 #include <asm/pgtable.h>
  34
  35 #include <media/videobuf-dma-sg.h>
  36
  37 #define MAGIC_DMABUF 0x19721112
  38 #define MAGIC_SG_MEM 0x17890714
  39
  40 #define MAGIC_CHECK(is, should)                                         \
  41         if (unlikely((is) != (should))) {                               \
  42                 printk(KERN_ERR "magic mismatch: %x (expected %x)\n",   \
  43                                 is, should);                            \
  44                 BUG();                                                  \
  45         }
  46
  47 static int debug;
  48 module_param(debug, int, 0644);
  49
  50 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
  51 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
  52 MODULE_LICENSE("GPL");
  53
  54 #define dprintk(level, fmt, arg...)                                     \
  55         if (debug >= level)                                             \
  56                 printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
  57
  58 /* --------------------------------------------------------------------- */
  59
  60 /*
  61  * Return a scatterlist for some page-aligned vmalloc()'ed memory
  62  * block (NULL on errors).  Memory for the scatterlist is allocated
  63  * using kmalloc.  The caller must free the memory.
  64  */
  65 static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
  66                                                   int nr_pages)
  67 {
  68         struct scatterlist *sglist;
  69         struct page *pg;
  70         int i;
  71
  72         sglist = vmalloc(nr_pages * sizeof(*sglist));
  73         if (NULL == sglist)
  74                 return NULL;
  75         memset(sglist, 0, nr_pages * sizeof(*sglist));
  76         sg_init_table(sglist, nr_pages);
  77         for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
  78                 pg = vmalloc_to_page(virt);
  79                 if (NULL == pg)
  80                         goto err;
  81                 BUG_ON(PageHighMem(pg));
  82                 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
  83         }
  84         return sglist;
  85
  86 err:
  87         vfree(sglist);
  88         return NULL;
  89 }
  90
  91 /*
  92  * Return a scatterlist for a an array of userpages (NULL on errors).
  93  * Memory for the scatterlist is allocated using kmalloc.  The caller
  94  * must free the memory.
  95  */
  96 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
  97                                                 int nr_pages, int offset)
  98 {
  99         struct scatterlist *sglist;
 100         int i;
 101
 102         if (NULL == pages[0])
 103                 return NULL;
 104         sglist = vmalloc(nr_pages * sizeof(*sglist));
 105         if (NULL == sglist)
 106                 return NULL;
 107         sg_init_table(sglist, nr_pages);
 108
 109         if (PageHighMem(pages[0]))
 110                 /* DMA to highmem pages might not work */
 111                 goto highmem;
 112         sg_set_page(&sglist[0], pages[0], PAGE_SIZE - offset, offset);
 113         for (i = 1; i < nr_pages; i++) {
 114                 if (NULL == pages[i])
 115                         goto nopage;
 116                 if (PageHighMem(pages[i]))
 117                         goto highmem;
 118                 sg_set_page(&sglist[i], pages[i], PAGE_SIZE, 0);
 119         }
 120         return sglist;
 121
 122 nopage:
 123         dprintk(2, "sgl: oops - no page\n");
 124         vfree(sglist);
 125         return NULL;
 126
 127 highmem:
 128         dprintk(2, "sgl: oops - highmem page\n");
 129         vfree(sglist);
 130         return NULL;
 131 }
 132
 133 /* --------------------------------------------------------------------- */
 134
 135 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
 136 {
 137         struct videobuf_dma_sg_memory *mem = buf->priv;
 138         BUG_ON(!mem);
 139
 140         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 141
 142         return &mem->dma;
 143 }
 144 EXPORT_SYMBOL_GPL(videobuf_to_dma);
 145
 146 void videobuf_dma_init(struct videobuf_dmabuf *dma)
 147 {
 148         memset(dma, 0, sizeof(*dma));
 149         dma->magic = MAGIC_DMABUF;
 150 }
 151 EXPORT_SYMBOL_GPL(videobuf_dma_init);
 152
 153 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 154                         int direction, unsigned long data, unsigned long size)
 155 {
 156         unsigned long first, last;
 157         int err, rw = 0;
 158
 159         dma->direction = direction;
 160         switch (dma->direction) {
 161         case DMA_FROM_DEVICE:
 162                 rw = READ;
 163                 break;
 164         case DMA_TO_DEVICE:
 165                 rw = WRITE;
 166                 break;
 167         default:
 168                 BUG();
 169         }
 170
 171         first = (data          & PAGE_MASK) >> PAGE_SHIFT;
 172         last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
 173         dma->offset   = data & ~PAGE_MASK;
 174         dma->nr_pages = last-first+1;
 175         dma->pages = kmalloc(dma->nr_pages * sizeof(struct page *), GFP_KERNEL);
 176         if (NULL == dma->pages)
 177                 return -ENOMEM;
 178
 179         dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
 180                 data, size, dma->nr_pages);
 181
 182         err = get_user_pages(current, current->mm,
 183                              data & PAGE_MASK, dma->nr_pages,
 184                              rw == READ, 1, /* force */
 185                              dma->pages, NULL);
 186
 187         if (err != dma->nr_pages) {
 188                 dma->nr_pages = (err >= 0) ? err : 0;
 189                 dprintk(1, "get_user_pages: err=%d [%d]\n", err, dma->nr_pages);
 190                 return err < 0 ? err : -EINVAL;
 191         }
 192         return 0;
 193 }
 194
 195 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 196                            unsigned long data, unsigned long size)
 197 {
 198         int ret;
 199
 200         down_read(&current->mm->mmap_sem);
 201         ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 202         up_read(&current->mm->mmap_sem);
 203
 204         return ret;
 205 }
 206 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
 207
 208 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 209                              int nr_pages)
 210 {
 211         dprintk(1, "init kernel [%d pages]\n", nr_pages);
 212
 213         dma->direction = direction;
 214         dma->vaddr = vmalloc_32(nr_pages << PAGE_SHIFT);
 215         if (NULL == dma->vaddr) {
 216                 dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
 217                 return -ENOMEM;
 218         }
 219
 220         dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
 221                                 (unsigned long)dma->vaddr,
 222                                 nr_pages << PAGE_SHIFT);
 223
 224         memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
 225         dma->nr_pages = nr_pages;
 226
 227         return 0;
 228 }
 229 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
 230
 231 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 232                               dma_addr_t addr, int nr_pages)
 233 {
 234         dprintk(1, "init overlay [%d pages @ bus 0x%lx]\n",
 235                 nr_pages, (unsigned long)addr);
 236         dma->direction = direction;
 237
 238         if (0 == addr)
 239                 return -EINVAL;
 240
 241         dma->bus_addr = addr;
 242         dma->nr_pages = nr_pages;
 243
 244         return 0;
 245 }
 246 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
 247
 248 int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 249 {
 250         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 251         BUG_ON(0 == dma->nr_pages);
 252
 253         if (dma->pages) {
 254                 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
 255                                                    dma->offset);
 256         }
 257         if (dma->vaddr) {
 258                 dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
 259                                                      dma->nr_pages);
 260         }
 261         if (dma->bus_addr) {
 262                 dma->sglist = vmalloc(sizeof(*dma->sglist));
 263                 if (NULL != dma->sglist) {
 264                         dma->sglen = 1;
 265                         sg_dma_address(&dma->sglist[0]) = dma->bus_addr
 266                                                         & PAGE_MASK;
 267                         dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
 268                         sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
 269                 }
 270         }
 271         if (NULL == dma->sglist) {
 272                 dprintk(1, "scatterlist is NULL\n");
 273                 return -ENOMEM;
 274         }
 275         if (!dma->bus_addr) {
 276                 dma->sglen = dma_map_sg(dev, dma->sglist,
 277                                         dma->nr_pages, dma->direction);
 278                 if (0 == dma->sglen) {
 279                         printk(KERN_WARNING
 280                                "%s: videobuf_map_sg failed\n", __func__);
 281                         vfree(dma->sglist);
 282                         dma->sglist = NULL;
 283                         dma->sglen = 0;
 284                         return -ENOMEM;
 285                 }
 286         }
 287
 288         return 0;
 289 }
 290 EXPORT_SYMBOL_GPL(videobuf_dma_map);
 291
 292 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 293 {
 294         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 295
 296         if (!dma->sglen)
 297                 return 0;
 298
 299         dma_unmap_sg(dev, dma->sglist, dma->sglen, dma->direction);
 300
 301         vfree(dma->sglist);
 302         dma->sglist = NULL;
 303         dma->sglen = 0;
 304
 305         return 0;
 306 }
 307 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
 308
 309 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 310 {
 311         int i;
 312         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 313         BUG_ON(dma->sglen);
 314
 315         if (dma->pages) {
 316                 for (i = 0; i < dma->nr_pages; i++)
 317                         page_cache_release(dma->pages[i]);
 318                 kfree(dma->pages);
 319                 dma->pages = NULL;
 320         }
 321
 322         vfree(dma->vaddr);
 323         dma->vaddr = NULL;
 324
 325         if (dma->bus_addr)
 326                 dma->bus_addr = 0;
 327         dma->direction = DMA_NONE;
 328
 329         return 0;
 330 }
 331 EXPORT_SYMBOL_GPL(videobuf_dma_free);
 332
 333 /* --------------------------------------------------------------------- */
 334
 335 static void videobuf_vm_open(struct vm_area_struct *vma)
 336 {
 337         struct videobuf_mapping *map = vma->vm_private_data;
 338
 339         dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
 340                 map->count, vma->vm_start, vma->vm_end);
 341
 342         map->count++;
 343 }
 344
 345 static void videobuf_vm_close(struct vm_area_struct *vma)
 346 {
 347         struct videobuf_mapping *map = vma->vm_private_data;
 348         struct videobuf_queue *q = map->q;
 349         struct videobuf_dma_sg_memory *mem;
 350         int i;
 351
 352         dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
 353                 map->count, vma->vm_start, vma->vm_end);
 354
 355         map->count--;
 356         if (0 == map->count) {
 357                 dprintk(1, "munmap %p q=%p\n", map, q);
 358                 mutex_lock(&q->vb_lock);
 359                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 360                         if (NULL == q->bufs[i])
 361                                 continue;
 362                         mem = q->bufs[i]->priv;
 363                         if (!mem)
 364                                 continue;
 365
 366                         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 367
 368                         if (q->bufs[i]->map != map)
 369                                 continue;
 370                         q->bufs[i]->map   = NULL;
 371                         q->bufs[i]->baddr = 0;
 372                         q->ops->buf_release(q, q->bufs[i]);
 373                 }
 374                 mutex_unlock(&q->vb_lock);
 375                 kfree(map);
 376         }
 377         return;
 378 }
 379
 380 /*
 381  * Get a anonymous page for the mapping.  Make sure we can DMA to that
 382  * memory location with 32bit PCI devices (i.e. don't use highmem for
 383  * now ...).  Bounce buffers don't work very well for the data rates
 384  * video capture has.
 385  */
 386 static int videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 387 {
 388         struct page *page;
 389
 390         dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
 391                 (unsigned long)vmf->virtual_address,
 392                 vma->vm_start, vma->vm_end);
 393
 394         page = alloc_page(GFP_USER | __GFP_DMA32);
 395         if (!page)
 396                 return VM_FAULT_OOM;
 397         clear_user_highpage(page, (unsigned long)vmf->virtual_address);
 398         vmf->page = page;
 399
 400         return 0;
 401 }
 402
 403 static const struct vm_operations_struct videobuf_vm_ops = {
 404         .open   = videobuf_vm_open,
 405         .close  = videobuf_vm_close,
 406         .fault  = videobuf_vm_fault,
 407 };
 408
 409 /* ---------------------------------------------------------------------
 410  * SG handlers for the generic methods
 411  */
 412
 413 /* Allocated area consists on 3 parts:
 414         struct video_buffer
 415         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 416         struct videobuf_dma_sg_memory
 417  */
 418
 419 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
 420 {
 421         struct videobuf_dma_sg_memory *mem;
 422         struct videobuf_buffer *vb;
 423
 424         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 425         if (!vb)
 426                 return vb;
 427
 428         mem = vb->priv = ((char *)vb) + size;
 429         mem->magic = MAGIC_SG_MEM;
 430
 431         videobuf_dma_init(&mem->dma);
 432
 433         dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 434                 __func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
 435                 mem, (long)sizeof(*mem));
 436
 437         return vb;
 438 }
 439
 440 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 441 {
 442         struct videobuf_dma_sg_memory *mem = buf->priv;
 443         BUG_ON(!mem);
 444
 445         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 446
 447         return mem->dma.vaddr;
 448 }
 449
 450 static int __videobuf_iolock(struct videobuf_queue *q,
 451                              struct videobuf_buffer *vb,
 452                              struct v4l2_framebuffer *fbuf)
 453 {
 454         int err, pages;
 455         dma_addr_t bus;
 456         struct videobuf_dma_sg_memory *mem = vb->priv;
 457         BUG_ON(!mem);
 458
 459         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 460
 461         switch (vb->memory) {
 462         case V4L2_MEMORY_MMAP:
 463         case V4L2_MEMORY_USERPTR:
 464                 if (0 == vb->baddr) {
 465                         /* no userspace addr -- kernel bounce buffer */
 466                         pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 467                         err = videobuf_dma_init_kernel(&mem->dma,
 468                                                        DMA_FROM_DEVICE,
 469                                                        pages);
 470                         if (0 != err)
 471                                 return err;
 472                 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
 473                         /* dma directly to userspace */
 474                         err = videobuf_dma_init_user(&mem->dma,
 475                                                      DMA_FROM_DEVICE,
 476                                                      vb->baddr, vb->bsize);
 477                         if (0 != err)
 478                                 return err;
 479                 } else {
 480                         /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 481                         buffers can only be called from videobuf_qbuf
 482                         we take current->mm->mmap_sem there, to prevent
 483                         locking inversion, so don't take it here */
 484
 485                         err = videobuf_dma_init_user_locked(&mem->dma,
 486                                                       DMA_FROM_DEVICE,
 487                                                       vb->baddr, vb->bsize);
 488                         if (0 != err)
 489                                 return err;
 490                 }
 491                 break;
 492         case V4L2_MEMORY_OVERLAY:
 493                 if (NULL == fbuf)
 494                         return -EINVAL;
 495                 /* FIXME: need sanity checks for vb->boff */
 496                 /*
 497                  * Using a double cast to avoid compiler warnings when
 498                  * building for PAE. Compiler doesn't like direct casting
 499                  * of a 32 bit ptr to 64 bit integer.
 500                  */
 501                 bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
 502                 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 503                 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
 504                                                 bus, pages);
 505                 if (0 != err)
 506                         return err;
 507                 break;
 508         default:
 509                 BUG();
 510         }
 511         err = videobuf_dma_map(q->dev, &mem->dma);
 512         if (0 != err)
 513                 return err;
 514
 515         return 0;
 516 }
 517
 518 static int __videobuf_sync(struct videobuf_queue *q,
 519                            struct videobuf_buffer *buf)
 520 {
 521         struct videobuf_dma_sg_memory *mem = buf->priv;
 522         BUG_ON(!mem || !mem->dma.sglen);
 523
 524         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 525         MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
 526
 527         dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
 528                             mem->dma.sglen, mem->dma.direction);
 529
 530         return 0;
 531 }
 532
 533 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 534                                   struct videobuf_buffer *buf,
 535                                   struct vm_area_struct *vma)
 536 {
 537         struct videobuf_dma_sg_memory *mem = buf->priv;
 538         struct videobuf_mapping *map;
 539         unsigned int first, last, size = 0, i;
 540         int retval;
 541
 542         retval = -EINVAL;
 543
 544         /* This function maintains backwards compatibility with V4L1 and will
 545          * map more than one buffer if the vma length is equal to the combined
 546          * size of multiple buffers than it will map them together.  See
 547          * VIDIOCGMBUF in the v4l spec
 548          *
 549          * TODO: Allow drivers to specify if they support this mode
 550          */
 551
 552         BUG_ON(!mem);
 553         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 554
 555         /* look for first buffer to map */
 556         for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 557                 if (buf == q->bufs[first]) {
 558                         size = PAGE_ALIGN(q->bufs[first]->bsize);
 559                         break;
 560                 }
 561         }
 562
 563         /* paranoia, should never happen since buf is always valid. */
 564         if (!size) {
 565                 dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
 566                                 (vma->vm_pgoff << PAGE_SHIFT));
 567                 goto done;
 568         }
 569
 570         last = first;
 571 #ifdef CONFIG_VIDEO_V4L1_COMPAT
 572         if (size != (vma->vm_end - vma->vm_start)) {
 573                 /* look for last buffer to map */
 574                 for (last = first + 1; last < VIDEO_MAX_FRAME; last++) {
 575                         if (NULL == q->bufs[last])
 576                                 continue;
 577                         if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
 578                                 continue;
 579                         if (q->bufs[last]->map) {
 580                                 retval = -EBUSY;
 581                                 goto done;
 582                         }
 583                         size += PAGE_ALIGN(q->bufs[last]->bsize);
 584                         if (size == (vma->vm_end - vma->vm_start))
 585                                 break;
 586                 }
 587                 if (VIDEO_MAX_FRAME == last) {
 588                         dprintk(1, "mmap app bug: size invalid [size=0x%lx]\n",
 589                                         (vma->vm_end - vma->vm_start));
 590                         goto done;
 591                 }
 592         }
 593 #endif
 594
 595         /* create mapping + update buffer list */
 596         retval = -ENOMEM;
 597         map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 598         if (NULL == map)
 599                 goto done;
 600
 601         size = 0;
 602         for (i = first; i <= last; i++) {
 603                 if (NULL == q->bufs[i])
 604                         continue;
 605                 q->bufs[i]->map   = map;
 606                 q->bufs[i]->baddr = vma->vm_start + size;
 607                 size += PAGE_ALIGN(q->bufs[i]->bsize);
 608         }
 609
 610         map->count    = 1;
 611         map->q        = q;
 612         vma->vm_ops   = &videobuf_vm_ops;
 613         vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
 614         vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
 615         vma->vm_private_data = map;
 616         dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
 617                 map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
 618         retval = 0;
 619
 620 done:
 621         return retval;
 622 }
 623
 624 static struct videobuf_qtype_ops sg_ops = {
 625         .magic        = MAGIC_QTYPE_OPS,
 626
 627         .alloc_vb     = __videobuf_alloc_vb,
 628         .iolock       = __videobuf_iolock,
 629         .sync         = __videobuf_sync,
 630         .mmap_mapper  = __videobuf_mmap_mapper,
 631         .vaddr        = __videobuf_to_vaddr,
 632 };
 633
 634 void *videobuf_sg_alloc(size_t size)
 635 {
 636         struct videobuf_queue q;
 637
 638         /* Required to make generic handler to call __videobuf_alloc */
 639         q.int_ops = &sg_ops;
 640
 641         q.msize = size;
 642
 643         return videobuf_alloc_vb(&q);
 644 }
 645 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
 646
 647 void videobuf_queue_sg_init(struct videobuf_queue *q,
 648                          const struct videobuf_queue_ops *ops,
 649                          struct device *dev,
 650                          spinlock_t *irqlock,
 651                          enum v4l2_buf_type type,
 652                          enum v4l2_field field,
 653                          unsigned int msize,
 654                          void *priv)
 655 {
 656         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 657                                  priv, &sg_ops);
 658 }
 659 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
 660