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 = kcalloc(nr_pages, sizeof(struct scatterlist), GFP_KERNEL);
  62         if (NULL == sglist)
  63                 return NULL;
  64         sg_init_table(sglist, nr_pages);
  65         for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
  66                 pg = vmalloc_to_page(virt);
  67                 if (NULL == pg)
  68                         goto err;
  69                 BUG_ON(PageHighMem(pg));
  70                 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
  71         }
  72         return sglist;
  73
  74  err:
  75         kfree(sglist);
  76         return NULL;
  77 }
  78
  79 struct scatterlist*
  80 videobuf_pages_to_sg(struct page **pages, int nr_pages, int offset)
  81 {
  82         struct scatterlist *sglist;
  83         int i;
  84
  85         if (NULL == pages[0])
  86                 return NULL;
  87         sglist = kmalloc(nr_pages * sizeof(*sglist), GFP_KERNEL);
  88         if (NULL == sglist)
  89                 return NULL;
  90         sg_init_table(sglist, nr_pages);
  91
  92         if (PageHighMem(pages[0]))
  93                 /* DMA to highmem pages might not work */
  94                 goto highmem;
  95         sg_set_page(&sglist[0], pages[0], PAGE_SIZE - offset, offset);
  96         for (i = 1; i < nr_pages; i++) {
  97                 if (NULL == pages[i])
  98                         goto nopage;
  99                 if (PageHighMem(pages[i]))
 100                         goto highmem;
 101                 sg_set_page(&sglist[i], pages[i], PAGE_SIZE, 0);
 102         }
 103         return sglist;
 104
 105  nopage:
 106         dprintk(2,"sgl: oops - no page\n");
 107         kfree(sglist);
 108         return NULL;
 109
 110  highmem:
 111         dprintk(2,"sgl: oops - highmem page\n");
 112         kfree(sglist);
 113         return NULL;
 114 }
 115
 116 /* --------------------------------------------------------------------- */
 117
 118 struct videobuf_dmabuf *videobuf_to_dma (struct videobuf_buffer *buf)
 119 {
 120         struct videobuf_dma_sg_memory *mem = buf->priv;
 121         BUG_ON(!mem);
 122
 123         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 124
 125         return &mem->dma;
 126 }
 127
 128 void videobuf_dma_init(struct videobuf_dmabuf *dma)
 129 {
 130         memset(dma,0,sizeof(*dma));
 131         dma->magic = MAGIC_DMABUF;
 132 }
 133
 134 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 135                         int direction, unsigned long data, unsigned long size)
 136 {
 137         unsigned long first,last;
 138         int err, rw = 0;
 139
 140         dma->direction = direction;
 141         switch (dma->direction) {
 142         case DMA_FROM_DEVICE:
 143                 rw = READ;
 144                 break;
 145         case DMA_TO_DEVICE:
 146                 rw = WRITE;
 147                 break;
 148         default:
 149                 BUG();
 150         }
 151
 152         first = (data          & PAGE_MASK) >> PAGE_SHIFT;
 153         last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
 154         dma->offset   = data & ~PAGE_MASK;
 155         dma->nr_pages = last-first+1;
 156         dma->pages = kmalloc(dma->nr_pages * sizeof(struct page*),
 157                              GFP_KERNEL);
 158         if (NULL == dma->pages)
 159                 return -ENOMEM;
 160         dprintk(1,"init user [0x%lx+0x%lx => %d pages]\n",
 161                 data,size,dma->nr_pages);
 162
 163         err = get_user_pages(current,current->mm,
 164                              data & PAGE_MASK, dma->nr_pages,
 165                              rw == READ, 1, /* force */
 166                              dma->pages, NULL);
 167
 168         if (err != dma->nr_pages) {
 169                 dma->nr_pages = (err >= 0) ? err : 0;
 170                 dprintk(1,"get_user_pages: err=%d [%d]\n",err,dma->nr_pages);
 171                 return err < 0 ? err : -EINVAL;
 172         }
 173         return 0;
 174 }
 175
 176 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
 177                            unsigned long data, unsigned long size)
 178 {
 179         int ret;
 180         down_read(&current->mm->mmap_sem);
 181         ret = videobuf_dma_init_user_locked(dma, direction, data, size);
 182         up_read(&current->mm->mmap_sem);
 183
 184         return ret;
 185 }
 186
 187 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
 188                              int nr_pages)
 189 {
 190         dprintk(1,"init kernel [%d pages]\n",nr_pages);
 191         dma->direction = direction;
 192         dma->vmalloc = vmalloc_32(nr_pages << PAGE_SHIFT);
 193         if (NULL == dma->vmalloc) {
 194                 dprintk(1,"vmalloc_32(%d pages) failed\n",nr_pages);
 195                 return -ENOMEM;
 196         }
 197         dprintk(1,"vmalloc is at addr 0x%08lx, size=%d\n",
 198                                 (unsigned long)dma->vmalloc,
 199                                 nr_pages << PAGE_SHIFT);
 200         memset(dma->vmalloc,0,nr_pages << PAGE_SHIFT);
 201         dma->nr_pages = nr_pages;
 202         return 0;
 203 }
 204
 205 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
 206                               dma_addr_t addr, int nr_pages)
 207 {
 208         dprintk(1,"init overlay [%d pages @ bus 0x%lx]\n",
 209                 nr_pages,(unsigned long)addr);
 210         dma->direction = direction;
 211         if (0 == addr)
 212                 return -EINVAL;
 213
 214         dma->bus_addr = addr;
 215         dma->nr_pages = nr_pages;
 216         return 0;
 217 }
 218
 219 int videobuf_dma_map(struct videobuf_queue* q, struct videobuf_dmabuf *dma)
 220 {
 221         MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
 222         BUG_ON(0 == dma->nr_pages);
 223
 224         if (dma->pages) {
 225                 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
 226                                                    dma->offset);
 227         }
 228         if (dma->vmalloc) {
 229                 dma->sglist = videobuf_vmalloc_to_sg
 230                                                 (dma->vmalloc,dma->nr_pages);
 231         }
 232         if (dma->bus_addr) {
 233                 dma->sglist = kmalloc(sizeof(struct scatterlist), GFP_KERNEL);
 234                 if (NULL != dma->sglist) {
 235                         dma->sglen  = 1;
 236                         sg_dma_address(&dma->sglist[0]) = dma->bus_addr & PAGE_MASK;
 237                         dma->sglist[0].offset           = dma->bus_addr & ~PAGE_MASK;
 238                         sg_dma_len(&dma->sglist[0])     = dma->nr_pages * PAGE_SIZE;
 239                 }
 240         }
 241         if (NULL == dma->sglist) {
 242                 dprintk(1,"scatterlist is NULL\n");
 243                 return -ENOMEM;
 244         }
 245         if (!dma->bus_addr) {
 246                 dma->sglen = dma_map_sg(q->dev, dma->sglist,
 247                                         dma->nr_pages, dma->direction);
 248                 if (0 == dma->sglen) {
 249                         printk(KERN_WARNING
 250                                "%s: videobuf_map_sg failed\n",__func__);
 251                         kfree(dma->sglist);
 252                         dma->sglist = NULL;
 253                         dma->sglen = 0;
 254                         return -EIO;
 255                 }
 256         }
 257         return 0;
 258 }
 259
 260 int videobuf_dma_sync(struct videobuf_queue *q, struct videobuf_dmabuf *dma)
 261 {
 262         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 263         BUG_ON(!dma->sglen);
 264
 265         dma_sync_sg_for_cpu(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 266         return 0;
 267 }
 268
 269 int videobuf_dma_unmap(struct videobuf_queue* q,struct videobuf_dmabuf *dma)
 270 {
 271         MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
 272         if (!dma->sglen)
 273                 return 0;
 274
 275         dma_unmap_sg(q->dev, dma->sglist, dma->nr_pages, dma->direction);
 276
 277         kfree(dma->sglist);
 278         dma->sglist = NULL;
 279         dma->sglen = 0;
 280         return 0;
 281 }
 282
 283 int videobuf_dma_free(struct videobuf_dmabuf *dma)
 284 {
 285         MAGIC_CHECK(dma->magic,MAGIC_DMABUF);
 286         BUG_ON(dma->sglen);
 287
 288         if (dma->pages) {
 289                 int i;
 290                 for (i=0; i < dma->nr_pages; i++)
 291                         page_cache_release(dma->pages[i]);
 292                 kfree(dma->pages);
 293                 dma->pages = NULL;
 294         }
 295
 296         vfree(dma->vmalloc);
 297         dma->vmalloc = NULL;
 298
 299         if (dma->bus_addr) {
 300                 dma->bus_addr = 0;
 301         }
 302         dma->direction = DMA_NONE;
 303         return 0;
 304 }
 305
 306 /* --------------------------------------------------------------------- */
 307
 308 int videobuf_sg_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
 309 {
 310         struct videobuf_queue q;
 311
 312         q.dev = dev;
 313
 314         return videobuf_dma_map(&q, dma);
 315 }
 316
 317 int videobuf_sg_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
 318 {
 319         struct videobuf_queue q;
 320
 321         q.dev = dev;
 322
 323         return videobuf_dma_unmap(&q, dma);
 324 }
 325
 326 /* --------------------------------------------------------------------- */
 327
 328 static void
 329 videobuf_vm_open(struct vm_area_struct *vma)
 330 {
 331         struct videobuf_mapping *map = vma->vm_private_data;
 332
 333         dprintk(2,"vm_open %p [count=%d,vma=%08lx-%08lx]\n",map,
 334                 map->count,vma->vm_start,vma->vm_end);
 335         map->count++;
 336 }
 337
 338 static void
 339 videobuf_vm_close(struct vm_area_struct *vma)
 340 {
 341         struct videobuf_mapping *map = vma->vm_private_data;
 342         struct videobuf_queue *q = map->q;
 343         struct videobuf_dma_sg_memory *mem;
 344         int i;
 345
 346         dprintk(2,"vm_close %p [count=%d,vma=%08lx-%08lx]\n",map,
 347                 map->count,vma->vm_start,vma->vm_end);
 348
 349         map->count--;
 350         if (0 == map->count) {
 351                 dprintk(1,"munmap %p q=%p\n",map,q);
 352                 mutex_lock(&q->vb_lock);
 353                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 354                         if (NULL == q->bufs[i])
 355                                 continue;
 356                         mem=q->bufs[i]->priv;
 357
 358                         if (!mem)
 359                                 continue;
 360
 361                         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 362
 363                         if (q->bufs[i]->map != map)
 364                                 continue;
 365                         q->bufs[i]->map   = NULL;
 366                         q->bufs[i]->baddr = 0;
 367                         q->ops->buf_release(q,q->bufs[i]);
 368                 }
 369                 mutex_unlock(&q->vb_lock);
 370                 kfree(map);
 371         }
 372         return;
 373 }
 374
 375 /*
 376  * Get a anonymous page for the mapping.  Make sure we can DMA to that
 377  * memory location with 32bit PCI devices (i.e. don't use highmem for
 378  * now ...).  Bounce buffers don't work very well for the data rates
 379  * video capture has.
 380  */
 381 static int
 382 videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 383 {
 384         struct page *page;
 385
 386         dprintk(3,"fault: fault @ %08lx [vma %08lx-%08lx]\n",
 387                 (unsigned long)vmf->virtual_address,vma->vm_start,vma->vm_end);
 388         page = alloc_page(GFP_USER | __GFP_DMA32);
 389         if (!page)
 390                 return VM_FAULT_OOM;
 391         clear_user_page(page_address(page), (unsigned long)vmf->virtual_address,
 392                         page);
 393         vmf->page = page;
 394         return 0;
 395 }
 396
 397 static 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  */