SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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/slab.h>
  25 #include <linux/interrupt.h>
  26
  27 #include <linux/dma-mapping.h>
  28 #include <linux/vmalloc.h>
  29 #include <linux/pagemap.h>
  30 #include <linux/scatterlist.h>
  31 #include <asm/page.h>
  32 #include <asm/pgtable.h>
  33
  34 #include <media/videobuf-dma-sg.h>
  35
  36 #define MAGIC_DMABUF 0x19721112
  37 #define MAGIC_SG_MEM 0x17890714
  38
  39 #define MAGIC_CHECK(is,should)  if (unlikely((is) != (should))) \
  40         { printk(KERN_ERR "magic mismatch: %x (expected %x)\n",is,should); BUG(); }
  41
  42 static int debug;
  43 module_param(debug, int, 0644);
  44
  45 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
  46 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
  47 MODULE_LICENSE("GPL");
  48
  49 #define dprintk(level, fmt, arg...)     if (debug >= level) \
  50         printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
  51
  52 /* --------------------------------------------------------------------- */
  53
  54 struct scatterlist*
  55 videobuf_vmalloc_to_sg(unsigned char *virt, int nr_pages)
  56 {
  57         struct scatterlist *sglist;
  58         struct page *pg;
  59         int i;
  60
  61         sglist = vmalloc(nr_pages * sizeof(*sglist));
  62         if (NULL == sglist)
  63                 return NULL;
  64         memset(sglist, 0, nr_pages * sizeof(*sglist));
  65         sg_init_table(sglist, nr_pages);
  66         for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
  67                 pg = vmalloc_to_page(virt);
  68                 if (NULL == pg)
  69                         goto err;
  70                 BUG_ON(PageHighMem(pg));
  71                 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
  72         }
  73         return sglist;
  74
  75  err:
  76         vfree(sglist);
  77         return NULL;
  78 }
  79
  80 struct scatterlist*
  81 videobuf_pages_to_sg(struct page **pages, int nr_pages, int offset)
  82 {
  83         struct scatterlist *sglist;
  84         int i;
  85
  86         if (NULL == pages[0])
  87                 return NULL;
  88         sglist = vmalloc(nr_pages * sizeof(*sglist));
  89         if (NULL == sglist)
  90                 return NULL;
  91         sg_init_table(sglist, nr_pages);
  92
  93         if (PageHighMem(pages[0]))
  94                 /* DMA to highmem pages might not work */
  95                 goto highmem;
  96         sg_set_page(&sglist[0], pages[0], PAGE_SIZE - offset, offset);
  97         for (i = 1; i < nr_pages; i++) {
  98                 if (NULL == pages[i])
  99                         goto nopage;
 100                 if (PageHighMem(pages[i]))
 101                         goto highmem;
 102                 sg_set_page(&sglist[i], pages[i], PAGE_SIZE, 0);
 103         }
 104         return sglist;
 105
 106  nopage:
 107         dprintk(2,"sgl: oops - no page\n");
 108         vfree(sglist);
 109         return NULL;
 110
 111  highmem:
 112         dprintk(2,"sgl: oops - highmem page\n");
 113         vfree(sglist);
 114         return NULL;
 115 }
 116
 117 /* --------------------------------------------------------------------- */
 118
 119 struct videobuf_dmabuf *videobuf_to_dma (struct videobuf_buffer *buf)
 120 {
 121         struct videobuf_dma_sg_memory *mem = buf->priv;
 122         BUG_ON(!mem);
 123
 124         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 125
 126         return &mem->dma;
 127 }
 128
 129 void videobuf_dma_init(struct videobuf_dmabuf *dma)
 130 {
 131         memset(dma,0,sizeof(*dma));
 132         dma->magic = MAGIC_DMABUF;
 133 }
 134
 135 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 136                         int direction, unsigned long data, unsigned long size)
 137 {
 138         unsigned long first,last;
 139         int err, rw = 0;
 140
 141         dma->direction = direction;
 142         switch (dma->direction) {
 143         case DMA_FROM_DEVICE:
 144                 rw = READ;
 145                 break;
 146         case DMA_TO_DEVICE:
 147                 rw = WRITE;
 148                 break;
 149         default:
 150                 BUG();
 151         }
 152
 153         first = (data          & PAGE_MASK) >> PAGE_SHIFT;
 154         last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
 155         dma->offset   = data & ~PAGE_MASK;
 156         dma->nr_pages = last-first+1;
 157         dma->pages = kmalloc(dma->nr_pages * sizeof(struct page*),
 158                              GFP_KERNEL);
 159         if (NULL == dma->pages)
 160                 return -ENOMEM;
 161         dprintk(1,"init user [0x%lx+0x%lx => %d pages]\n",
 162                 data,size,dma->nr_pages);
 163
 164         err = get_user_pages(current,current->mm,
 165                              data & PAGE_MASK, dma->nr_pages,
 166                              rw == READ, 1, /* force */
 167                              dma->pages, NULL);
 168
 169         if (err != dma->nr_pages) {
 170                 dma->nr_pages = (err >= 0) ? err : 0;
 171                 dprintk(1,"get_user_pages: err=%d [%d]\n",err,dma->nr_pages);
 172                 return err < 0 ? err : -EINVAL;
 173         }
 174         return 0;
 175 }
 176
 177 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 178                            unsigned long data, unsigned long size)
 179 {
 180         int ret;
 181         down_read(&current->mm->mmap_sem);
 182         ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 183         up_read(&current->mm->mmap_sem);
 184
 185         return ret;
 186 }
 187
 188 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 189                              int nr_pages)
 190 {
 191         dprintk(1,"init kernel [%d pages]\n",nr_pages);
 192         dma->direction = direction;
 193         dma->vmalloc = vmalloc_32(nr_pages << PAGE_SHIFT);
 194         if (NULL == dma->vmalloc) {
 195                 dprintk(1,"vmalloc_32(%d pages) failed\n",nr_pages);
 196                 return -ENOMEM;
 197         }
 198         dprintk(1,"vmalloc is at addr 0x%08lx, size=%d\n",
 199                                 (unsigned long)dma->vmalloc,
 200                                 nr_pages << PAGE_SHIFT);
 201         memset(dma->vmalloc,0,nr_pages << PAGE_SHIFT);
 202         dma->nr_pages = nr_pages;
 203         return 0;
 204 }
 205
 206 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 207                               dma_addr_t addr, int nr_pages)
 208 {
 209         dprintk(1,"init overlay [%d pages @ bus 0x%lx]\n",
 210                 nr_pages,(unsigned long)addr);
 211         dma->direction = direction;
 212         if (0 == addr)
 213                 return -EINVAL;
 214
 215         dma->bus_addr = addr;
 216         dma->nr_pages = nr_pages;
 217         return 0;
 218 }
 219
 220 int videobuf_dma_map(struct videobuf_queue* q, struct videobuf_dmabuf *dma)
 221 {
 222         MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
 223         BUG_ON(0 == dma->nr_pages);
 224
 225         if (dma->pages) {
 226                 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
 227                                                    dma->offset);
 228         }
 229         if (dma->vmalloc) {
 230                 dma->sglist = videobuf_vmalloc_to_sg
 231                                                 (dma->vmalloc,dma->nr_pages);
 232         }
 233         if (dma->bus_addr) {
 234                 dma->sglist = vmalloc(sizeof(*dma->sglist));
 235                 if (NULL != dma->sglist) {
 236                         dma->sglen  = 1;
 237                         sg_dma_address(&dma->sglist[0]) = dma->bus_addr & PAGE_MASK;
 238                         dma->sglist[0].offset           = dma->bus_addr & ~PAGE_MASK;
 239                         sg_dma_len(&dma->sglist[0])     = dma->nr_pages * PAGE_SIZE;
 240                 }
 241         }
 242         if (NULL == dma->sglist) {
 243                 dprintk(1,"scatterlist is NULL\n");
 244                 return -ENOMEM;
 245         }
 246         if (!dma->bus_addr) {
 247                 dma->sglen = dma_map_sg(q->dev, dma->sglist,
 248                                         dma->nr_pages, dma->direction);
 249                 if (0 == dma->sglen) {
 250                         printk(KERN_WARNING
 251                                "%s: videobuf_map_sg failed\n",__func__);
 252                         vfree(dma->sglist);
 253                         dma->sglist = NULL;
 254                         dma->sglen = 0;
 255                         return -ENOMEM;
 256                 }
 257         }
 258         return 0;
 259 }
 260
 261 int videobuf_dma_sync(struct videobuf_queue *q, struct videobuf_dmabuf *dma)
 262 {
 263         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 264         BUG_ON(!dma->sglen);
 265
 266         dma_sync_sg_for_cpu(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 267         return 0;
 268 }
 269
 270 int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma)
 271 {
 272         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 273         if (!dma->sglen)
 274                 return 0;
 275
 276         dma_unmap_sg(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 277
 278         vfree(dma->sglist);
 279         dma->sglist = NULL;
 280         dma->sglen = 0;
 281         return 0;
 282 }
 283
 284 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 285 {
 286         MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
 287         BUG_ON(dma->sglen);
 288
 289         if (dma->pages) {
 290                 int i;
 291                 for (i=0; i < dma->nr_pages; i++)
 292                         page_cache_release(dma->pages[i]);
 293                 kfree(dma->pages);
 294                 dma->pages = NULL;
 295         }
 296
 297         vfree(dma->vmalloc);
 298         dma->vmalloc = NULL;
 299
 300         if (dma->bus_addr) {
 301                 dma->bus_addr = 0;
 302         }
 303         dma->direction = DMA_NONE;
 304         return 0;
 305 }
 306
 307 /* --------------------------------------------------------------------- */
 308
 309 int videobuf_sg_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 310 {
 311         struct videobuf_queue q;
 312
 313         q.dev = dev;
 314
 315         return videobuf_dma_map(&q, dma);
 316 }
 317
 318 int videobuf_sg_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 319 {
 320         struct videobuf_queue q;
 321
 322         q.dev = dev;
 323
 324         return videobuf_dma_unmap(&q, dma);
 325 }
 326
 327 /* --------------------------------------------------------------------- */
 328
 329 static void
 330 videobuf_vm_open(struct vm_area_struct *vma)
 331 {
 332         struct videobuf_mapping *map = vma->vm_private_data;
 333
 334         dprintk(2,"vm_open %p [count=%d,vma=%08lx-%08lx]\n",map,
 335                 map->count,vma->vm_start,vma->vm_end);
 336         map->count++;
 337 }
 338
 339 static void
 340 videobuf_vm_close(struct vm_area_struct *vma)
 341 {
 342         struct videobuf_mapping *map = vma->vm_private_data;
 343         struct videobuf_queue *q = map->q;
 344         struct videobuf_dma_sg_memory *mem;
 345         int i;
 346
 347         dprintk(2,"vm_close %p [count=%d,vma=%08lx-%08lx]\n",map,
 348                 map->count,vma->vm_start,vma->vm_end);
 349
 350         map->count--;
 351         if (0 == map->count) {
 352                 dprintk(1,"munmap %p q=%p\n",map,q);
 353                 mutex_lock(&q->vb_lock);
 354                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 355                         if (NULL == q->bufs[i])
 356                                 continue;
 357                         mem=q->bufs[i]->priv;
 358
 359                         if (!mem)
 360                                 continue;
 361
 362                         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 363
 364                         if (q->bufs[i]->map != map)
 365                                 continue;
 366                         q->bufs[i]->map   = NULL;
 367                         q->bufs[i]->baddr = 0;
 368                         q->ops->buf_release(q,q->bufs[i]);
 369                 }
 370                 mutex_unlock(&q->vb_lock);
 371                 kfree(map);
 372         }
 373         return;
 374 }
 375
 376 /*
 377  * Get a anonymous page for the mapping.  Make sure we can DMA to that
 378  * memory location with 32bit PCI devices (i.e. don't use highmem for
 379  * now ...).  Bounce buffers don't work very well for the data rates
 380  * video capture has.
 381  */
 382 static int
 383 videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 384 {
 385         struct page *page;
 386
 387         dprintk(3,"fault: fault @ %08lx [vma %08lx-%08lx]\n",
 388                 (unsigned long)vmf->virtual_address,vma->vm_start,vma->vm_end);
 389         page = alloc_page(GFP_USER | __GFP_DMA32);
 390         if (!page)
 391                 return VM_FAULT_OOM;
 392         clear_user_highpage(page, (unsigned long)vmf->virtual_address);
 393         vmf->page = page;
 394         return 0;
 395 }
 396
 397 static const struct vm_operations_struct videobuf_vm_ops =
 398 {
 399         .open     = videobuf_vm_open,
 400         .close    = videobuf_vm_close,
 401         .fault    = videobuf_vm_fault,
 402 };
 403
 404 /* ---------------------------------------------------------------------
 405  * SG handlers for the generic methods
 406  */
 407
 408 /* Allocated area consists on 3 parts:
 409         struct video_buffer
 410         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 411         struct videobuf_dma_sg_memory
 412  */
 413
 414 static void *__videobuf_alloc(size_t size)
 415 {
 416         struct videobuf_dma_sg_memory *mem;
 417         struct videobuf_buffer *vb;
 418
 419         vb = kzalloc(size+sizeof(*mem),GFP_KERNEL);
 420
 421         mem = vb->priv = ((char *)vb)+size;
 422         mem->magic=MAGIC_SG_MEM;
 423
 424         videobuf_dma_init(&mem->dma);
 425
 426         dprintk(1,"%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 427                 __func__,vb,(long)sizeof(*vb),(long)size-sizeof(*vb),
 428                 mem,(long)sizeof(*mem));
 429
 430         return vb;
 431 }
 432
 433 static void *__videobuf_to_vmalloc (struct videobuf_buffer *buf)
 434 {
 435         struct videobuf_dma_sg_memory *mem = buf->priv;
 436         BUG_ON(!mem);
 437
 438         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 439
 440         return mem->dma.vmalloc;
 441 }
 442
 443 static int __videobuf_iolock (struct videobuf_queue* q,
 444                               struct videobuf_buffer *vb,
 445                               struct v4l2_framebuffer *fbuf)
 446 {
 447         int err,pages;
 448         dma_addr_t bus;
 449         struct videobuf_dma_sg_memory *mem = vb->priv;
 450         BUG_ON(!mem);
 451
 452         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 453
 454         switch (vb->memory) {
 455         case V4L2_MEMORY_MMAP:
 456         case V4L2_MEMORY_USERPTR:
 457                 if (0 == vb->baddr) {
 458                         /* no userspace addr -- kernel bounce buffer */
 459                         pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 460                         err = videobuf_dma_init_kernel( &mem->dma,
 461                                                         DMA_FROM_DEVICE,
 462                                                         pages );
 463                         if (0 != err)
 464                                 return err;
 465                 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
 466                         /* dma directly to userspace */
 467                         err = videobuf_dma_init_user( &mem->dma,
 468                                                       DMA_FROM_DEVICE,
 469                                                       vb->baddr,vb->bsize );
 470                         if (0 != err)
 471                                 return err;
 472                 } else {
 473                         /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 474                         buffers can only be called from videobuf_qbuf
 475                         we take current->mm->mmap_sem there, to prevent
 476                         locking inversion, so don't take it here */
 477
 478                         err = videobuf_dma_init_user_locked(&mem->dma,
 479                                                       DMA_FROM_DEVICE,
 480                                                       vb->baddr, vb->bsize);
 481                         if (0 != err)
 482                                 return err;
 483                 }
 484                 break;
 485         case V4L2_MEMORY_OVERLAY:
 486                 if (NULL == fbuf)
 487                         return -EINVAL;
 488                 /* FIXME: need sanity checks for vb->boff */
 489                 /*
 490                  * Using a double cast to avoid compiler warnings when
 491                  * building for PAE. Compiler doesn't like direct casting
 492                  * of a 32 bit ptr to 64 bit integer.
 493                  */
 494                 bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
 495                 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 496                 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
 497                                                 bus, pages);
 498                 if (0 != err)
 499                         return err;
 500                 break;
 501         default:
 502                 BUG();
 503         }
 504         err = videobuf_dma_map(q, &mem->dma);
 505         if (0 != err)
 506                 return err;
 507
 508         return 0;
 509 }
 510
 511 static int __videobuf_sync(struct videobuf_queue *q,
 512                            struct videobuf_buffer *buf)
 513 {
 514         struct videobuf_dma_sg_memory *mem = buf->priv;
 515         BUG_ON(!mem);
 516         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 517
 518         return  videobuf_dma_sync(q,&mem->dma);
 519 }
 520
 521 static int __videobuf_mmap_free(struct videobuf_queue *q)
 522 {
 523         int i;
 524
 525         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 526                 if (q->bufs[i]) {
 527                         if (q->bufs[i]->map)
 528                                 return -EBUSY;
 529                 }
 530         }
 531
 532         return 0;
 533 }
 534
 535 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 536                          struct vm_area_struct *vma)
 537 {
 538         struct videobuf_dma_sg_memory *mem;
 539         struct videobuf_mapping *map;
 540         unsigned int first,last,size,i;
 541         int retval;
 542
 543         retval = -EINVAL;
 544         if (!(vma->vm_flags & VM_WRITE)) {
 545                 dprintk(1,"mmap app bug: PROT_WRITE please\n");
 546                 goto done;
 547         }
 548         if (!(vma->vm_flags & VM_SHARED)) {
 549                 dprintk(1,"mmap app bug: MAP_SHARED please\n");
 550                 goto done;
 551         }
 552
 553         /* This function maintains backwards compatibility with V4L1 and will
 554          * map more than one buffer if the vma length is equal to the combined
 555          * size of multiple buffers than it will map them together.  See
 556          * VIDIOCGMBUF in the v4l spec
 557          *
 558          * TODO: Allow drivers to specify if they support this mode
 559          */
 560
 561         /* look for first buffer to map */
 562         for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 563                 if (NULL == q->bufs[first])
 564                         continue;
 565                 mem=q->bufs[first]->priv;
 566                 BUG_ON(!mem);
 567                 MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 568
 569                 if (V4L2_MEMORY_MMAP != q->bufs[first]->memory)
 570                         continue;
 571                 if (q->bufs[first]->boff == (vma->vm_pgoff << PAGE_SHIFT))
 572                         break;
 573         }
 574         if (VIDEO_MAX_FRAME == first) {
 575                 dprintk(1,"mmap app bug: offset invalid [offset=0x%lx]\n",
 576                         (vma->vm_pgoff << PAGE_SHIFT));
 577                 goto done;
 578         }
 579
 580         /* look for last buffer to map */
 581         for (size = 0, last = first; last < VIDEO_MAX_FRAME; last++) {
 582                 if (NULL == q->bufs[last])
 583                         continue;
 584                 if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
 585                         continue;
 586                 if (q->bufs[last]->map) {
 587                         retval = -EBUSY;
 588                         goto done;
 589                 }
 590                 size += q->bufs[last]->bsize;
 591                 if (size == (vma->vm_end - vma->vm_start))
 592                         break;
 593         }
 594         if (VIDEO_MAX_FRAME == last) {
 595                 dprintk(1,"mmap app bug: size invalid [size=0x%lx]\n",
 596                         (vma->vm_end - vma->vm_start));
 597                 goto done;
 598         }
 599
 600         /* create mapping + update buffer list */
 601         retval = -ENOMEM;
 602         map = kmalloc(sizeof(struct videobuf_mapping),GFP_KERNEL);
 603         if (NULL == map)
 604                 goto done;
 605
 606         size = 0;
 607         for (i = first; i <= last; i++) {
 608                 if (NULL == q->bufs[i])
 609                         continue;
 610                 q->bufs[i]->map   = map;
 611                 q->bufs[i]->baddr = vma->vm_start + size;
 612                 size += q->bufs[i]->bsize;
 613         }
 614
 615         map->count    = 1;
 616         map->start    = vma->vm_start;
 617         map->end      = vma->vm_end;
 618         map->q        = q;
 619         vma->vm_ops   = &videobuf_vm_ops;
 620         vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
 621         vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
 622         vma->vm_private_data = map;
 623         dprintk(1,"mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
 624                 map,q,vma->vm_start,vma->vm_end,vma->vm_pgoff,first,last);
 625         retval = 0;
 626
 627  done:
 628         return retval;
 629 }
 630
 631 static int __videobuf_copy_to_user ( struct videobuf_queue *q,
 632                                 char __user *data, size_t count,
 633                                 int nonblocking )
 634 {
 635         struct videobuf_dma_sg_memory *mem = q->read_buf->priv;
 636         BUG_ON(!mem);
 637         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 638
 639         /* copy to userspace */
 640         if (count > q->read_buf->size - q->read_off)
 641                 count = q->read_buf->size - q->read_off;
 642
 643         if (copy_to_user(data, mem->dma.vmalloc+q->read_off, count))
 644                 return -EFAULT;
 645
 646         return count;
 647 }
 648
 649 static int __videobuf_copy_stream ( struct videobuf_queue *q,
 650                                 char __user *data, size_t count, size_t pos,
 651                                 int vbihack, int nonblocking )
 652 {
 653         unsigned int  *fc;
 654         struct videobuf_dma_sg_memory *mem = q->read_buf->priv;
 655         BUG_ON(!mem);
 656         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 657
 658         if (vbihack) {
 659                 /* dirty, undocumented hack -- pass the frame counter
 660                         * within the last four bytes of each vbi data block.
 661                         * We need that one to maintain backward compatibility
 662                         * to all vbi decoding software out there ... */
 663                 fc  = (unsigned int*)mem->dma.vmalloc;
 664                 fc += (q->read_buf->size>>2) -1;
 665                 *fc = q->read_buf->field_count >> 1;
 666                 dprintk(1,"vbihack: %d\n",*fc);
 667         }
 668
 669         /* copy stuff using the common method */
 670         count = __videobuf_copy_to_user (q,data,count,nonblocking);
 671
 672         if ( (count==-EFAULT) && (0 == pos) )
 673                 return -EFAULT;
 674
 675         return count;
 676 }
 677
 678 static struct videobuf_qtype_ops sg_ops = {
 679         .magic        = MAGIC_QTYPE_OPS,
 680
 681         .alloc        = __videobuf_alloc,
 682         .iolock       = __videobuf_iolock,
 683         .sync         = __videobuf_sync,
 684         .mmap_free    = __videobuf_mmap_free,
 685         .mmap_mapper  = __videobuf_mmap_mapper,
 686         .video_copy_to_user = __videobuf_copy_to_user,
 687         .copy_stream  = __videobuf_copy_stream,
 688         .vmalloc      = __videobuf_to_vmalloc,
 689 };
 690
 691 void *videobuf_sg_alloc(size_t size)
 692 {
 693         struct videobuf_queue q;
 694
 695         /* Required to make generic handler to call __videobuf_alloc */
 696         q.int_ops = &sg_ops;
 697
 698         q.msize = size;
 699
 700         return videobuf_alloc(&q);
 701 }
 702
 703 void videobuf_queue_sg_init(struct videobuf_queue* q,
 704                          struct videobuf_queue_ops *ops,
 705                          struct device *dev,
 706                          spinlock_t *irqlock,
 707                          enum v4l2_buf_type type,
 708                          enum v4l2_field field,
 709                          unsigned int msize,
 710                          void *priv)
 711 {
 712         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 713                                  priv, &sg_ops);
 714 }
 715
 716 /* --------------------------------------------------------------------- */
 717
 718 EXPORT_SYMBOL_GPL(videobuf_vmalloc_to_sg);
 719
 720 EXPORT_SYMBOL_GPL(videobuf_to_dma);
 721 EXPORT_SYMBOL_GPL(videobuf_dma_init);
 722 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
 723 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
 724 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
 725 EXPORT_SYMBOL_GPL(videobuf_dma_map);
 726 EXPORT_SYMBOL_GPL(videobuf_dma_sync);
 727 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
 728 EXPORT_SYMBOL_GPL(videobuf_dma_free);
 729
 730 EXPORT_SYMBOL_GPL(videobuf_sg_dma_map);
 731 EXPORT_SYMBOL_GPL(videobuf_sg_dma_unmap);
 732 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
 733
 734 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
 735
 736 /*
 737  * Local variables:
 738  * c-basic-offset: 8
 739  * End:
 740  */