drivers/media/v4l2-core/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 = vzalloc(nr_pages * sizeof(*sglist));
  73         if (NULL == sglist)
  74                 return NULL;
  75         sg_init_table(sglist, nr_pages);
  76         for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
  77                 pg = vmalloc_to_page(virt);
  78                 if (NULL == pg)
  79                         goto err;
  80                 BUG_ON(PageHighMem(pg));
  81                 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
  82         }
  83         return sglist;
  84
  85 err:
  86         vfree(sglist);
  87         return NULL;
  88 }
  89
  90 /*
  91  * Return a scatterlist for a an array of userpages (NULL on errors).
  92  * Memory for the scatterlist is allocated using kmalloc.  The caller
  93  * must free the memory.
  94  */
  95 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
  96                                         int nr_pages, int offset, size_t size)
  97 {
  98         struct scatterlist *sglist;
  99         int i;
 100
 101         if (NULL == pages[0])
 102                 return NULL;
 103         sglist = vmalloc(nr_pages * sizeof(*sglist));
 104         if (NULL == sglist)
 105                 return NULL;
 106         sg_init_table(sglist, nr_pages);
 107
 108         if (PageHighMem(pages[0]))
 109                 /* DMA to highmem pages might not work */
 110                 goto highmem;
 111         sg_set_page(&sglist[0], pages[0],
 112                         min_t(size_t, PAGE_SIZE - offset, size), offset);
 113         size -= min_t(size_t, PAGE_SIZE - offset, size);
 114         for (i = 1; i < nr_pages; i++) {
 115                 if (NULL == pages[i])
 116                         goto nopage;
 117                 if (PageHighMem(pages[i]))
 118                         goto highmem;
 119                 sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
 120                 size -= min_t(size_t, PAGE_SIZE, size);
 121         }
 122         return sglist;
 123
 124 nopage:
 125         dprintk(2, "sgl: oops - no page\n");
 126         vfree(sglist);
 127         return NULL;
 128
 129 highmem:
 130         dprintk(2, "sgl: oops - highmem page\n");
 131         vfree(sglist);
 132         return NULL;
 133 }
 134
 135 /* --------------------------------------------------------------------- */
 136
 137 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
 138 {
 139         struct videobuf_dma_sg_memory *mem = buf->priv;
 140         BUG_ON(!mem);
 141
 142         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 143
 144         return &mem->dma;
 145 }
 146 EXPORT_SYMBOL_GPL(videobuf_to_dma);
 147
 148 void videobuf_dma_init(struct videobuf_dmabuf *dma)
 149 {
 150         memset(dma, 0, sizeof(*dma));
 151         dma->magic = MAGIC_DMABUF;
 152 }
 153 EXPORT_SYMBOL_GPL(videobuf_dma_init);
 154
 155 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 156                         int direction, unsigned long data, unsigned long size)
 157 {
 158         unsigned long first, last;
 159         int err, rw = 0;
 160
 161         dma->direction = direction;
 162         switch (dma->direction) {
 163         case DMA_FROM_DEVICE:
 164                 rw = READ;
 165                 break;
 166         case DMA_TO_DEVICE:
 167                 rw = WRITE;
 168                 break;
 169         default:
 170                 BUG();
 171         }
 172
 173         first = (data          & PAGE_MASK) >> PAGE_SHIFT;
 174         last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
 175         dma->offset = data & ~PAGE_MASK;
 176         dma->size = size;
 177         dma->nr_pages = last-first+1;
 178         dma->pages = kmalloc(dma->nr_pages * sizeof(struct page *), GFP_KERNEL);
 179         if (NULL == dma->pages)
 180                 return -ENOMEM;
 181
 182         dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
 183                 data, size, dma->nr_pages);
 184
 185         err = get_user_pages(current, current->mm,
 186                              data & PAGE_MASK, dma->nr_pages,
 187                              rw == READ, 1, /* force */
 188                              dma->pages, NULL);
 189
 190         if (err != dma->nr_pages) {
 191                 dma->nr_pages = (err >= 0) ? err : 0;
 192                 dprintk(1, "get_user_pages: err=%d [%d]\n", err, dma->nr_pages);
 193                 return err < 0 ? err : -EINVAL;
 194         }
 195         return 0;
 196 }
 197
 198 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 199                            unsigned long data, unsigned long size)
 200 {
 201         int ret;
 202
 203         down_read(&current->mm->mmap_sem);
 204         ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 205         up_read(&current->mm->mmap_sem);
 206
 207         return ret;
 208 }
 209 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
 210
 211 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 212                              int nr_pages)
 213 {
 214         int i;
 215
 216         dprintk(1, "init kernel [%d pages]\n", nr_pages);
 217
 218         dma->direction = direction;
 219         dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
 220                                    GFP_KERNEL);
 221         if (!dma->vaddr_pages)
 222                 return -ENOMEM;
 223
 224         dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
 225         if (!dma->dma_addr) {
 226                 kfree(dma->vaddr_pages);
 227                 return -ENOMEM;
 228         }
 229         for (i = 0; i < nr_pages; i++) {
 230                 void *addr;
 231
 232                 addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
 233                                           &(dma->dma_addr[i]), GFP_KERNEL);
 234                 if (addr == NULL)
 235                         goto out_free_pages;
 236
 237                 dma->vaddr_pages[i] = virt_to_page(addr);
 238         }
 239         dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
 240                           PAGE_KERNEL);
 241         if (NULL == dma->vaddr) {
 242                 dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
 243                 goto out_free_pages;
 244         }
 245
 246         dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
 247                                 (unsigned long)dma->vaddr,
 248                                 nr_pages << PAGE_SHIFT);
 249
 250         memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
 251         dma->nr_pages = nr_pages;
 252
 253         return 0;
 254 out_free_pages:
 255         while (i > 0) {
 256                 void *addr;
 257
 258                 i--;
 259                 addr = page_address(dma->vaddr_pages[i]);
 260                 dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
 261         }
 262         kfree(dma->dma_addr);
 263         dma->dma_addr = NULL;
 264         kfree(dma->vaddr_pages);
 265         dma->vaddr_pages = NULL;
 266
 267         return -ENOMEM;
 268
 269 }
 270 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
 271
 272 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 273                               dma_addr_t addr, int nr_pages)
 274 {
 275         dprintk(1, "init overlay [%d pages @ bus 0x%lx]\n",
 276                 nr_pages, (unsigned long)addr);
 277         dma->direction = direction;
 278
 279         if (0 == addr)
 280                 return -EINVAL;
 281
 282         dma->bus_addr = addr;
 283         dma->nr_pages = nr_pages;
 284
 285         return 0;
 286 }
 287 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
 288
 289 int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 290 {
 291         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 292         BUG_ON(0 == dma->nr_pages);
 293
 294         if (dma->pages) {
 295                 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
 296                                                    dma->offset, dma->size);
 297         }
 298         if (dma->vaddr) {
 299                 dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
 300                                                      dma->nr_pages);
 301         }
 302         if (dma->bus_addr) {
 303                 dma->sglist = vmalloc(sizeof(*dma->sglist));
 304                 if (NULL != dma->sglist) {
 305                         dma->sglen = 1;
 306                         sg_dma_address(&dma->sglist[0]) = dma->bus_addr
 307                                                         & PAGE_MASK;
 308                         dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
 309                         sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
 310                 }
 311         }
 312         if (NULL == dma->sglist) {
 313                 dprintk(1, "scatterlist is NULL\n");
 314                 return -ENOMEM;
 315         }
 316         if (!dma->bus_addr) {
 317                 dma->sglen = dma_map_sg(dev, dma->sglist,
 318                                         dma->nr_pages, dma->direction);
 319                 if (0 == dma->sglen) {
 320                         printk(KERN_WARNING
 321                                "%s: videobuf_map_sg failed\n", __func__);
 322                         vfree(dma->sglist);
 323                         dma->sglist = NULL;
 324                         dma->sglen = 0;
 325                         return -ENOMEM;
 326                 }
 327         }
 328
 329         return 0;
 330 }
 331 EXPORT_SYMBOL_GPL(videobuf_dma_map);
 332
 333 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 334 {
 335         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 336
 337         if (!dma->sglen)
 338                 return 0;
 339
 340         dma_unmap_sg(dev, dma->sglist, dma->sglen, dma->direction);
 341
 342         vfree(dma->sglist);
 343         dma->sglist = NULL;
 344         dma->sglen = 0;
 345
 346         return 0;
 347 }
 348 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
 349
 350 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 351 {
 352         int i;
 353         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 354         BUG_ON(dma->sglen);
 355
 356         if (dma->pages) {
 357                 for (i = 0; i < dma->nr_pages; i++)
 358                         page_cache_release(dma->pages[i]);
 359                 kfree(dma->pages);
 360                 dma->pages = NULL;
 361         }
 362
 363         if (dma->dma_addr) {
 364                 for (i = 0; i < dma->nr_pages; i++) {
 365                         void *addr;
 366
 367                         addr = page_address(dma->vaddr_pages[i]);
 368                         dma_free_coherent(dma->dev, PAGE_SIZE, addr,
 369                                           dma->dma_addr[i]);
 370                 }
 371                 kfree(dma->dma_addr);
 372                 dma->dma_addr = NULL;
 373                 kfree(dma->vaddr_pages);
 374                 dma->vaddr_pages = NULL;
 375                 vunmap(dma->vaddr);
 376                 dma->vaddr = NULL;
 377         }
 378
 379         if (dma->bus_addr)
 380                 dma->bus_addr = 0;
 381         dma->direction = DMA_NONE;
 382
 383         return 0;
 384 }
 385 EXPORT_SYMBOL_GPL(videobuf_dma_free);
 386
 387 /* --------------------------------------------------------------------- */
 388
 389 static void videobuf_vm_open(struct vm_area_struct *vma)
 390 {
 391         struct videobuf_mapping *map = vma->vm_private_data;
 392
 393         dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
 394                 map->count, vma->vm_start, vma->vm_end);
 395
 396         map->count++;
 397 }
 398
 399 static void videobuf_vm_close(struct vm_area_struct *vma)
 400 {
 401         struct videobuf_mapping *map = vma->vm_private_data;
 402         struct videobuf_queue *q = map->q;
 403         struct videobuf_dma_sg_memory *mem;
 404         int i;
 405
 406         dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
 407                 map->count, vma->vm_start, vma->vm_end);
 408
 409         map->count--;
 410         if (0 == map->count) {
 411                 dprintk(1, "munmap %p q=%p\n", map, q);
 412                 videobuf_queue_lock(q);
 413                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 414                         if (NULL == q->bufs[i])
 415                                 continue;
 416                         mem = q->bufs[i]->priv;
 417                         if (!mem)
 418                                 continue;
 419
 420                         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 421
 422                         if (q->bufs[i]->map != map)
 423                                 continue;
 424                         q->bufs[i]->map   = NULL;
 425                         q->bufs[i]->baddr = 0;
 426                         q->ops->buf_release(q, q->bufs[i]);
 427                 }
 428                 videobuf_queue_unlock(q);
 429                 kfree(map);
 430         }
 431         return;
 432 }
 433
 434 /*
 435  * Get a anonymous page for the mapping.  Make sure we can DMA to that
 436  * memory location with 32bit PCI devices (i.e. don't use highmem for
 437  * now ...).  Bounce buffers don't work very well for the data rates
 438  * video capture has.
 439  */
 440 static int videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 441 {
 442         struct page *page;
 443
 444         dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
 445                 (unsigned long)vmf->virtual_address,
 446                 vma->vm_start, vma->vm_end);
 447
 448         page = alloc_page(GFP_USER | __GFP_DMA32);
 449         if (!page)
 450                 return VM_FAULT_OOM;
 451         clear_user_highpage(page, (unsigned long)vmf->virtual_address);
 452         vmf->page = page;
 453
 454         return 0;
 455 }
 456
 457 static const struct vm_operations_struct videobuf_vm_ops = {
 458         .open   = videobuf_vm_open,
 459         .close  = videobuf_vm_close,
 460         .fault  = videobuf_vm_fault,
 461 };
 462
 463 /* ---------------------------------------------------------------------
 464  * SG handlers for the generic methods
 465  */
 466
 467 /* Allocated area consists on 3 parts:
 468         struct video_buffer
 469         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 470         struct videobuf_dma_sg_memory
 471  */
 472
 473 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
 474 {
 475         struct videobuf_dma_sg_memory *mem;
 476         struct videobuf_buffer *vb;
 477
 478         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 479         if (!vb)
 480                 return vb;
 481
 482         mem = vb->priv = ((char *)vb) + size;
 483         mem->magic = MAGIC_SG_MEM;
 484
 485         videobuf_dma_init(&mem->dma);
 486
 487         dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 488                 __func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
 489                 mem, (long)sizeof(*mem));
 490
 491         return vb;
 492 }
 493
 494 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 495 {
 496         struct videobuf_dma_sg_memory *mem = buf->priv;
 497         BUG_ON(!mem);
 498
 499         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 500
 501         return mem->dma.vaddr;
 502 }
 503
 504 static int __videobuf_iolock(struct videobuf_queue *q,
 505                              struct videobuf_buffer *vb,
 506                              struct v4l2_framebuffer *fbuf)
 507 {
 508         int err, pages;
 509         dma_addr_t bus;
 510         struct videobuf_dma_sg_memory *mem = vb->priv;
 511         BUG_ON(!mem);
 512
 513         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 514
 515         if (!mem->dma.dev)
 516                 mem->dma.dev = q->dev;
 517         else
 518                 WARN_ON(mem->dma.dev != q->dev);
 519
 520         switch (vb->memory) {
 521         case V4L2_MEMORY_MMAP:
 522         case V4L2_MEMORY_USERPTR:
 523                 if (0 == vb->baddr) {
 524                         /* no userspace addr -- kernel bounce buffer */
 525                         pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 526                         err = videobuf_dma_init_kernel(&mem->dma,
 527                                                        DMA_FROM_DEVICE,
 528                                                        pages);
 529                         if (0 != err)
 530                                 return err;
 531                 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
 532                         /* dma directly to userspace */
 533                         err = videobuf_dma_init_user(&mem->dma,
 534                                                      DMA_FROM_DEVICE,
 535                                                      vb->baddr, vb->bsize);
 536                         if (0 != err)
 537                                 return err;
 538                 } else {
 539                         /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 540                         buffers can only be called from videobuf_qbuf
 541                         we take current->mm->mmap_sem there, to prevent
 542                         locking inversion, so don't take it here */
 543
 544                         err = videobuf_dma_init_user_locked(&mem->dma,
 545                                                       DMA_FROM_DEVICE,
 546                                                       vb->baddr, vb->bsize);
 547                         if (0 != err)
 548                                 return err;
 549                 }
 550                 break;
 551         case V4L2_MEMORY_OVERLAY:
 552                 if (NULL == fbuf)
 553                         return -EINVAL;
 554                 /* FIXME: need sanity checks for vb->boff */
 555                 /*
 556                  * Using a double cast to avoid compiler warnings when
 557                  * building for PAE. Compiler doesn't like direct casting
 558                  * of a 32 bit ptr to 64 bit integer.
 559                  */
 560                 bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
 561                 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 562                 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
 563                                                 bus, pages);
 564                 if (0 != err)
 565                         return err;
 566                 break;
 567         default:
 568                 BUG();
 569         }
 570         err = videobuf_dma_map(q->dev, &mem->dma);
 571         if (0 != err)
 572                 return err;
 573
 574         return 0;
 575 }
 576
 577 static int __videobuf_sync(struct videobuf_queue *q,
 578                            struct videobuf_buffer *buf)
 579 {
 580         struct videobuf_dma_sg_memory *mem = buf->priv;
 581         BUG_ON(!mem || !mem->dma.sglen);
 582
 583         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 584         MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
 585
 586         dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
 587                             mem->dma.sglen, mem->dma.direction);
 588
 589         return 0;
 590 }
 591
 592 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 593                                   struct videobuf_buffer *buf,
 594                                   struct vm_area_struct *vma)
 595 {
 596         struct videobuf_dma_sg_memory *mem = buf->priv;
 597         struct videobuf_mapping *map;
 598         unsigned int first, last, size = 0, i;
 599         int retval;
 600
 601         retval = -EINVAL;
 602
 603         BUG_ON(!mem);
 604         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 605
 606         /* look for first buffer to map */
 607         for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 608                 if (buf == q->bufs[first]) {
 609                         size = PAGE_ALIGN(q->bufs[first]->bsize);
 610                         break;
 611                 }
 612         }
 613
 614         /* paranoia, should never happen since buf is always valid. */
 615         if (!size) {
 616                 dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
 617                                 (vma->vm_pgoff << PAGE_SHIFT));
 618                 goto done;
 619         }
 620
 621         last = first;
 622
 623         /* create mapping + update buffer list */
 624         retval = -ENOMEM;
 625         map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 626         if (NULL == map)
 627                 goto done;
 628
 629         size = 0;
 630         for (i = first; i <= last; i++) {
 631                 if (NULL == q->bufs[i])
 632                         continue;
 633                 q->bufs[i]->map   = map;
 634                 q->bufs[i]->baddr = vma->vm_start + size;
 635                 size += PAGE_ALIGN(q->bufs[i]->bsize);
 636         }
 637
 638         map->count    = 1;
 639         map->q        = q;
 640         vma->vm_ops   = &videobuf_vm_ops;
 641         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 642         vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
 643         vma->vm_private_data = map;
 644         dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
 645                 map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
 646         retval = 0;
 647
 648 done:
 649         return retval;
 650 }
 651
 652 static struct videobuf_qtype_ops sg_ops = {
 653         .magic        = MAGIC_QTYPE_OPS,
 654
 655         .alloc_vb     = __videobuf_alloc_vb,
 656         .iolock       = __videobuf_iolock,
 657         .sync         = __videobuf_sync,
 658         .mmap_mapper  = __videobuf_mmap_mapper,
 659         .vaddr        = __videobuf_to_vaddr,
 660 };
 661
 662 void *videobuf_sg_alloc(size_t size)
 663 {
 664         struct videobuf_queue q;
 665
 666         /* Required to make generic handler to call __videobuf_alloc */
 667         q.int_ops = &sg_ops;
 668
 669         q.msize = size;
 670
 671         return videobuf_alloc_vb(&q);
 672 }
 673 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
 674
 675 void videobuf_queue_sg_init(struct videobuf_queue *q,
 676                          const struct videobuf_queue_ops *ops,
 677                          struct device *dev,
 678                          spinlock_t *irqlock,
 679                          enum v4l2_buf_type type,
 680                          enum v4l2_field field,
 681                          unsigned int msize,
 682                          void *priv,
 683                          struct mutex *ext_lock)
 684 {
 685         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 686                                  priv, &sg_ops, ext_lock);
 687 }
 688 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
 689