git.oblomov.eu Git - 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 = 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_highpage(page, (unsigned long)vmf->virtual_address);
 392         vmf->page = page;
 393         return 0;
 394 }
 395
 396 static struct vm_operations_struct videobuf_vm_ops =
 397 {
 398         .open     = videobuf_vm_open,
 399         .close    = videobuf_vm_close,
 400         .fault    = videobuf_vm_fault,
 401 };
 402
 403 /* ---------------------------------------------------------------------
 404  * SG handlers for the generic methods
 405  */
 406
 407 /* Allocated area consists on 3 parts:
 408         struct video_buffer
 409         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 410         struct videobuf_dma_sg_memory
 411  */
 412
 413 static void *__videobuf_alloc(size_t size)
 414 {
 415         struct videobuf_dma_sg_memory *mem;
 416         struct videobuf_buffer *vb;
 417
 418         vb = kzalloc(size+sizeof(*mem),GFP_KERNEL);
 419
 420         mem = vb->priv = ((char *)vb)+size;
 421         mem->magic=MAGIC_SG_MEM;
 422
 423         videobuf_dma_init(&mem->dma);
 424
 425         dprintk(1,"%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 426                 __func__,vb,(long)sizeof(*vb),(long)size-sizeof(*vb),
 427                 mem,(long)sizeof(*mem));
 428
 429         return vb;
 430 }
 431
 432 static void *__videobuf_to_vmalloc (struct videobuf_buffer *buf)
 433 {
 434         struct videobuf_dma_sg_memory *mem = buf->priv;
 435         BUG_ON(!mem);
 436
 437         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 438
 439         return mem->dma.vmalloc;
 440 }
 441
 442 static int __videobuf_iolock (struct videobuf_queue* q,
 443                               struct videobuf_buffer *vb,
 444                               struct v4l2_framebuffer *fbuf)
 445 {
 446         int err,pages;
 447         dma_addr_t bus;
 448         struct videobuf_dma_sg_memory *mem = vb->priv;
 449         BUG_ON(!mem);
 450
 451         MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
 452
 453         switch (vb->memory) {
 454         case V4L2_MEMORY_MMAP:
 455         case V4L2_MEMORY_USERPTR:
 456                 if (0 == vb->baddr) {
 457                         /* no userspace addr -- kernel bounce buffer */
 458                         pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 459                         err = videobuf_dma_init_kernel( &mem->dma,
 460                                                         DMA_FROM_DEVICE,
 461                                                         pages );
 462                         if (0 != err)
 463                                 return err;
 464                 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
 465                         /* dma directly to userspace */
 466                         err = videobuf_dma_init_user( &mem->dma,
 467                                                       DMA_FROM_DEVICE,
 468                                                       vb->baddr,vb->bsize );
 469                         if (0 != err)
 470                                 return err;
 471                 } else {
 472                         /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
 473                         buffers can only be called from videobuf_qbuf
 474                         we take current->mm->mmap_sem there, to prevent
 475                         locking inversion, so don't take it here */
 476
 477                         err = videobuf_dma_init_user_locked(&mem->dma,
 478                                                       DMA_FROM_DEVICE,
 479                                                       vb->baddr, vb->bsize);
 480                         if (0 != err)
 481                                 return err;
 482                 }
 483                 break;
 484         case V4L2_MEMORY_OVERLAY:
 485                 if (NULL == fbuf)
 486                         return -EINVAL;
 487                 /* FIXME: need sanity checks for vb->boff */
 488                 /*
 489                  * Using a double cast to avoid compiler warnings when
 490                  * building for PAE. Compiler doesn't like direct casting
 491                  * of a 32 bit ptr to 64 bit integer.
 492                  */
 493                 bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
 494                 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
 495                 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
 496                                                 bus, pages);
 497                 if (0 != err)
 498                         return err;
 499                 break;
 500         default:
 501                 BUG();
 502         }
 503         err = videobuf_dma_map(q, &mem->dma);
 504         if (0 != err)
 505                 return err;
 506
 507         return 0;
 508 }
 509
 510 static int __videobuf_sync(struct videobuf_queue *q,
 511                            struct videobuf_buffer *buf)
 512 {
 513         struct videobuf_dma_sg_memory *mem = buf->priv;
 514         BUG_ON(!mem);
 515         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 516
 517         return  videobuf_dma_sync(q,&mem->dma);
 518 }
 519
 520 static int __videobuf_mmap_free(struct videobuf_queue *q)
 521 {
 522         int i;
 523
 524         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 525                 if (q->bufs[i]) {
 526                         if (q->bufs[i]->map)
 527                                 return -EBUSY;
 528                 }
 529         }
 530
 531         return 0;
 532 }
 533
 534 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 535                          struct vm_area_struct *vma)
 536 {
 537         struct videobuf_dma_sg_memory *mem;
 538         struct videobuf_mapping *map;
 539         unsigned int first,last,size,i;
 540         int retval;
 541
 542         retval = -EINVAL;
 543         if (!(vma->vm_flags & VM_WRITE)) {
 544                 dprintk(1,"mmap app bug: PROT_WRITE please\n");
 545                 goto done;
 546         }
 547         if (!(vma->vm_flags & VM_SHARED)) {
 548                 dprintk(1,"mmap app bug: MAP_SHARED please\n");
 549                 goto done;
 550         }
 551
 552         /* This function maintains backwards compatibility with V4L1 and will
 553          * map more than one buffer if the vma length is equal to the combined
 554          * size of multiple buffers than it will map them together.  See
 555          * VIDIOCGMBUF in the v4l spec
 556          *
 557          * TODO: Allow drivers to specify if they support this mode
 558          */
 559
 560         /* look for first buffer to map */
 561         for (first = 0; first < VIDEO_MAX_FRAME; first++) {
 562                 if (NULL == q->bufs[first])
 563                         continue;
 564                 mem=q->bufs[first]->priv;
 565                 BUG_ON(!mem);
 566                 MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 567
 568                 if (V4L2_MEMORY_MMAP != q->bufs[first]->memory)
 569                         continue;
 570                 if (q->bufs[first]->boff == (vma->vm_pgoff << PAGE_SHIFT))
 571                         break;
 572         }
 573         if (VIDEO_MAX_FRAME == first) {
 574                 dprintk(1,"mmap app bug: offset invalid [offset=0x%lx]\n",
 575                         (vma->vm_pgoff << PAGE_SHIFT));
 576                 goto done;
 577         }
 578
 579         /* look for last buffer to map */
 580         for (size = 0, last = first; last < VIDEO_MAX_FRAME; last++) {
 581                 if (NULL == q->bufs[last])
 582                         continue;
 583                 if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
 584                         continue;
 585                 if (q->bufs[last]->map) {
 586                         retval = -EBUSY;
 587                         goto done;
 588                 }
 589                 size += q->bufs[last]->bsize;
 590                 if (size == (vma->vm_end - vma->vm_start))
 591                         break;
 592         }
 593         if (VIDEO_MAX_FRAME == last) {
 594                 dprintk(1,"mmap app bug: size invalid [size=0x%lx]\n",
 595                         (vma->vm_end - vma->vm_start));
 596                 goto done;
 597         }
 598
 599         /* create mapping + update buffer list */
 600         retval = -ENOMEM;
 601         map = kmalloc(sizeof(struct videobuf_mapping),GFP_KERNEL);
 602         if (NULL == map)
 603                 goto done;
 604
 605         size = 0;
 606         for (i = first; i <= last; i++) {
 607                 if (NULL == q->bufs[i])
 608                         continue;
 609                 q->bufs[i]->map   = map;
 610                 q->bufs[i]->baddr = vma->vm_start + size;
 611                 size += q->bufs[i]->bsize;
 612         }
 613
 614         map->count    = 1;
 615         map->start    = vma->vm_start;
 616         map->end      = vma->vm_end;
 617         map->q        = q;
 618         vma->vm_ops   = &videobuf_vm_ops;
 619         vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
 620         vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
 621         vma->vm_private_data = map;
 622         dprintk(1,"mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
 623                 map,q,vma->vm_start,vma->vm_end,vma->vm_pgoff,first,last);
 624         retval = 0;
 625
 626  done:
 627         return retval;
 628 }
 629
 630 static int __videobuf_copy_to_user ( struct videobuf_queue *q,
 631                                 char __user *data, size_t count,
 632                                 int nonblocking )
 633 {
 634         struct videobuf_dma_sg_memory *mem = q->read_buf->priv;
 635         BUG_ON(!mem);
 636         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 637
 638         /* copy to userspace */
 639         if (count > q->read_buf->size - q->read_off)
 640                 count = q->read_buf->size - q->read_off;
 641
 642         if (copy_to_user(data, mem->dma.vmalloc+q->read_off, count))
 643                 return -EFAULT;
 644
 645         return count;
 646 }
 647
 648 static int __videobuf_copy_stream ( struct videobuf_queue *q,
 649                                 char __user *data, size_t count, size_t pos,
 650                                 int vbihack, int nonblocking )
 651 {
 652         unsigned int  *fc;
 653         struct videobuf_dma_sg_memory *mem = q->read_buf->priv;
 654         BUG_ON(!mem);
 655         MAGIC_CHECK(mem->magic,MAGIC_SG_MEM);
 656
 657         if (vbihack) {
 658                 /* dirty, undocumented hack -- pass the frame counter
 659                         * within the last four bytes of each vbi data block.
 660                         * We need that one to maintain backward compatibility
 661                         * to all vbi decoding software out there ... */
 662                 fc  = (unsigned int*)mem->dma.vmalloc;
 663                 fc += (q->read_buf->size>>2) -1;
 664                 *fc = q->read_buf->field_count >> 1;
 665                 dprintk(1,"vbihack: %d\n",*fc);
 666         }
 667
 668         /* copy stuff using the common method */
 669         count = __videobuf_copy_to_user (q,data,count,nonblocking);
 670
 671         if ( (count==-EFAULT) && (0 == pos) )
 672                 return -EFAULT;
 673
 674         return count;
 675 }
 676
 677 static struct videobuf_qtype_ops sg_ops = {
 678         .magic        = MAGIC_QTYPE_OPS,
 679
 680         .alloc        = __videobuf_alloc,
 681         .iolock       = __videobuf_iolock,
 682         .sync         = __videobuf_sync,
 683         .mmap_free    = __videobuf_mmap_free,
 684         .mmap_mapper  = __videobuf_mmap_mapper,
 685         .video_copy_to_user = __videobuf_copy_to_user,
 686         .copy_stream  = __videobuf_copy_stream,
 687         .vmalloc      = __videobuf_to_vmalloc,
 688 };
 689
 690 void *videobuf_sg_alloc(size_t size)
 691 {
 692         struct videobuf_queue q;
 693
 694         /* Required to make generic handler to call __videobuf_alloc */
 695         q.int_ops = &sg_ops;
 696
 697         q.msize = size;
 698
 699         return videobuf_alloc(&q);
 700 }
 701
 702 void videobuf_queue_sg_init(struct videobuf_queue* q,
 703                          struct videobuf_queue_ops *ops,
 704                          struct device *dev,
 705                          spinlock_t *irqlock,
 706                          enum v4l2_buf_type type,
 707                          enum v4l2_field field,
 708                          unsigned int msize,
 709                          void *priv)
 710 {
 711         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 712                                  priv, &sg_ops);
 713 }
 714
 715 /* --------------------------------------------------------------------- */
 716
 717 EXPORT_SYMBOL_GPL(videobuf_vmalloc_to_sg);
 718
 719 EXPORT_SYMBOL_GPL(videobuf_to_dma);
 720 EXPORT_SYMBOL_GPL(videobuf_dma_init);
 721 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
 722 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
 723 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
 724 EXPORT_SYMBOL_GPL(videobuf_dma_map);
 725 EXPORT_SYMBOL_GPL(videobuf_dma_sync);
 726 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
 727 EXPORT_SYMBOL_GPL(videobuf_dma_free);
 728
 729 EXPORT_SYMBOL_GPL(videobuf_sg_dma_map);
 730 EXPORT_SYMBOL_GPL(videobuf_sg_dma_unmap);
 731 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
 732
 733 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
 734
 735 /*
 736  * Local variables:
 737  * c-basic-offset: 8
 738  * End:
 739  */