drivers/media/v4l2-core/videobuf-core.c

   1 /*
   2  * generic helper functions for handling video4linux capture buffers
   3  *
   4  * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
   5  *
   6  * Highly based on video-buf written originally by:
   7  * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
   8  * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
   9  * (c) 2006 Ted Walther and John Sokol
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2
  14  */
  15
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/mm.h>
  20 #include <linux/sched.h>
  21 #include <linux/slab.h>
  22 #include <linux/interrupt.h>
  23
  24 #include <media/videobuf-core.h>
  25
  26 #define MAGIC_BUFFER 0x20070728
  27 #define MAGIC_CHECK(is, should)                                         \
  28         do {                                                            \
  29                 if (unlikely((is) != (should))) {                       \
  30                         printk(KERN_ERR                                 \
  31                                 "magic mismatch: %x (expected %x)\n",   \
  32                                         is, should);                    \
  33                         BUG();                                          \
  34                 }                                                       \
  35         } while (0)
  36
  37 static int debug;
  38 module_param(debug, int, 0644);
  39
  40 MODULE_DESCRIPTION("helper module to manage video4linux buffers");
  41 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
  42 MODULE_LICENSE("GPL");
  43
  44 #define dprintk(level, fmt, arg...)                                     \
  45         do {                                                            \
  46                 if (debug >= level)                                     \
  47                         printk(KERN_DEBUG "vbuf: " fmt, ## arg);        \
  48         } while (0)
  49
  50 /* --------------------------------------------------------------------- */
  51
  52 #define CALL(q, f, arg...)                                              \
  53         ((q->int_ops->f) ? q->int_ops->f(arg) : 0)
  54
  55 struct videobuf_buffer *videobuf_alloc_vb(struct videobuf_queue *q)
  56 {
  57         struct videobuf_buffer *vb;
  58
  59         BUG_ON(q->msize < sizeof(*vb));
  60
  61         if (!q->int_ops || !q->int_ops->alloc_vb) {
  62                 printk(KERN_ERR "No specific ops defined!\n");
  63                 BUG();
  64         }
  65
  66         vb = q->int_ops->alloc_vb(q->msize);
  67         if (NULL != vb) {
  68                 init_waitqueue_head(&vb->done);
  69                 vb->magic = MAGIC_BUFFER;
  70         }
  71
  72         return vb;
  73 }
  74 EXPORT_SYMBOL_GPL(videobuf_alloc_vb);
  75
  76 static int is_state_active_or_queued(struct videobuf_queue *q, struct videobuf_buffer *vb)
  77 {
  78         unsigned long flags;
  79         bool rc;
  80
  81         spin_lock_irqsave(q->irqlock, flags);
  82         rc = vb->state != VIDEOBUF_ACTIVE && vb->state != VIDEOBUF_QUEUED;
  83         spin_unlock_irqrestore(q->irqlock, flags);
  84         return rc;
  85 };
  86
  87 int videobuf_waiton(struct videobuf_queue *q, struct videobuf_buffer *vb,
  88                 int non_blocking, int intr)
  89 {
  90         bool is_ext_locked;
  91         int ret = 0;
  92
  93         MAGIC_CHECK(vb->magic, MAGIC_BUFFER);
  94
  95         if (non_blocking) {
  96                 if (is_state_active_or_queued(q, vb))
  97                         return 0;
  98                 return -EAGAIN;
  99         }
 100
 101         is_ext_locked = q->ext_lock && mutex_is_locked(q->ext_lock);
 102
 103         /* Release vdev lock to prevent this wait from blocking outside access to
 104            the device. */
 105         if (is_ext_locked)
 106                 mutex_unlock(q->ext_lock);
 107         if (intr)
 108                 ret = wait_event_interruptible(vb->done, is_state_active_or_queued(q, vb));
 109         else
 110                 wait_event(vb->done, is_state_active_or_queued(q, vb));
 111         /* Relock */
 112         if (is_ext_locked)
 113                 mutex_lock(q->ext_lock);
 114
 115         return ret;
 116 }
 117 EXPORT_SYMBOL_GPL(videobuf_waiton);
 118
 119 int videobuf_iolock(struct videobuf_queue *q, struct videobuf_buffer *vb,
 120                     struct v4l2_framebuffer *fbuf)
 121 {
 122         MAGIC_CHECK(vb->magic, MAGIC_BUFFER);
 123         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 124
 125         return CALL(q, iolock, q, vb, fbuf);
 126 }
 127 EXPORT_SYMBOL_GPL(videobuf_iolock);
 128
 129 void *videobuf_queue_to_vaddr(struct videobuf_queue *q,
 130                               struct videobuf_buffer *buf)
 131 {
 132         if (q->int_ops->vaddr)
 133                 return q->int_ops->vaddr(buf);
 134         return NULL;
 135 }
 136 EXPORT_SYMBOL_GPL(videobuf_queue_to_vaddr);
 137
 138 /* --------------------------------------------------------------------- */
 139
 140
 141 void videobuf_queue_core_init(struct videobuf_queue *q,
 142                          const struct videobuf_queue_ops *ops,
 143                          struct device *dev,
 144                          spinlock_t *irqlock,
 145                          enum v4l2_buf_type type,
 146                          enum v4l2_field field,
 147                          unsigned int msize,
 148                          void *priv,
 149                          struct videobuf_qtype_ops *int_ops,
 150                          struct mutex *ext_lock)
 151 {
 152         BUG_ON(!q);
 153         memset(q, 0, sizeof(*q));
 154         q->irqlock   = irqlock;
 155         q->ext_lock  = ext_lock;
 156         q->dev       = dev;
 157         q->type      = type;
 158         q->field     = field;
 159         q->msize     = msize;
 160         q->ops       = ops;
 161         q->priv_data = priv;
 162         q->int_ops   = int_ops;
 163
 164         /* All buffer operations are mandatory */
 165         BUG_ON(!q->ops->buf_setup);
 166         BUG_ON(!q->ops->buf_prepare);
 167         BUG_ON(!q->ops->buf_queue);
 168         BUG_ON(!q->ops->buf_release);
 169
 170         /* Lock is mandatory for queue_cancel to work */
 171         BUG_ON(!irqlock);
 172
 173         /* Having implementations for abstract methods are mandatory */
 174         BUG_ON(!q->int_ops);
 175
 176         mutex_init(&q->vb_lock);
 177         init_waitqueue_head(&q->wait);
 178         INIT_LIST_HEAD(&q->stream);
 179 }
 180 EXPORT_SYMBOL_GPL(videobuf_queue_core_init);
 181
 182 /* Locking: Only usage in bttv unsafe find way to remove */
 183 int videobuf_queue_is_busy(struct videobuf_queue *q)
 184 {
 185         int i;
 186
 187         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 188
 189         if (q->streaming) {
 190                 dprintk(1, "busy: streaming active\n");
 191                 return 1;
 192         }
 193         if (q->reading) {
 194                 dprintk(1, "busy: pending read #1\n");
 195                 return 1;
 196         }
 197         if (q->read_buf) {
 198                 dprintk(1, "busy: pending read #2\n");
 199                 return 1;
 200         }
 201         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 202                 if (NULL == q->bufs[i])
 203                         continue;
 204                 if (q->bufs[i]->map) {
 205                         dprintk(1, "busy: buffer #%d mapped\n", i);
 206                         return 1;
 207                 }
 208                 if (q->bufs[i]->state == VIDEOBUF_QUEUED) {
 209                         dprintk(1, "busy: buffer #%d queued\n", i);
 210                         return 1;
 211                 }
 212                 if (q->bufs[i]->state == VIDEOBUF_ACTIVE) {
 213                         dprintk(1, "busy: buffer #%d avtive\n", i);
 214                         return 1;
 215                 }
 216         }
 217         return 0;
 218 }
 219 EXPORT_SYMBOL_GPL(videobuf_queue_is_busy);
 220
 221 /**
 222  * __videobuf_free() - free all the buffers and their control structures
 223  *
 224  * This function can only be called if streaming/reading is off, i.e. no buffers
 225  * are under control of the driver.
 226  */
 227 /* Locking: Caller holds q->vb_lock */
 228 static int __videobuf_free(struct videobuf_queue *q)
 229 {
 230         int i;
 231
 232         dprintk(1, "%s\n", __func__);
 233         if (!q)
 234                 return 0;
 235
 236         if (q->streaming || q->reading) {
 237                 dprintk(1, "Cannot free buffers when streaming or reading\n");
 238                 return -EBUSY;
 239         }
 240
 241         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 242
 243         for (i = 0; i < VIDEO_MAX_FRAME; i++)
 244                 if (q->bufs[i] && q->bufs[i]->map) {
 245                         dprintk(1, "Cannot free mmapped buffers\n");
 246                         return -EBUSY;
 247                 }
 248
 249         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 250                 if (NULL == q->bufs[i])
 251                         continue;
 252                 q->ops->buf_release(q, q->bufs[i]);
 253                 kfree(q->bufs[i]);
 254                 q->bufs[i] = NULL;
 255         }
 256
 257         return 0;
 258 }
 259
 260 /* Locking: Caller holds q->vb_lock */
 261 void videobuf_queue_cancel(struct videobuf_queue *q)
 262 {
 263         unsigned long flags = 0;
 264         int i;
 265
 266         q->streaming = 0;
 267         q->reading  = 0;
 268         wake_up_interruptible_sync(&q->wait);
 269
 270         /* remove queued buffers from list */
 271         spin_lock_irqsave(q->irqlock, flags);
 272         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 273                 if (NULL == q->bufs[i])
 274                         continue;
 275                 if (q->bufs[i]->state == VIDEOBUF_QUEUED) {
 276                         list_del(&q->bufs[i]->queue);
 277                         q->bufs[i]->state = VIDEOBUF_ERROR;
 278                         wake_up_all(&q->bufs[i]->done);
 279                 }
 280         }
 281         spin_unlock_irqrestore(q->irqlock, flags);
 282
 283         /* free all buffers + clear queue */
 284         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 285                 if (NULL == q->bufs[i])
 286                         continue;
 287                 q->ops->buf_release(q, q->bufs[i]);
 288         }
 289         INIT_LIST_HEAD(&q->stream);
 290 }
 291 EXPORT_SYMBOL_GPL(videobuf_queue_cancel);
 292
 293 /* --------------------------------------------------------------------- */
 294
 295 /* Locking: Caller holds q->vb_lock */
 296 enum v4l2_field videobuf_next_field(struct videobuf_queue *q)
 297 {
 298         enum v4l2_field field = q->field;
 299
 300         BUG_ON(V4L2_FIELD_ANY == field);
 301
 302         if (V4L2_FIELD_ALTERNATE == field) {
 303                 if (V4L2_FIELD_TOP == q->last) {
 304                         field   = V4L2_FIELD_BOTTOM;
 305                         q->last = V4L2_FIELD_BOTTOM;
 306                 } else {
 307                         field   = V4L2_FIELD_TOP;
 308                         q->last = V4L2_FIELD_TOP;
 309                 }
 310         }
 311         return field;
 312 }
 313 EXPORT_SYMBOL_GPL(videobuf_next_field);
 314
 315 /* Locking: Caller holds q->vb_lock */
 316 static void videobuf_status(struct videobuf_queue *q, struct v4l2_buffer *b,
 317                             struct videobuf_buffer *vb, enum v4l2_buf_type type)
 318 {
 319         MAGIC_CHECK(vb->magic, MAGIC_BUFFER);
 320         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 321
 322         b->index    = vb->i;
 323         b->type     = type;
 324
 325         b->memory   = vb->memory;
 326         switch (b->memory) {
 327         case V4L2_MEMORY_MMAP:
 328                 b->m.offset  = vb->boff;
 329                 b->length    = vb->bsize;
 330                 break;
 331         case V4L2_MEMORY_USERPTR:
 332                 b->m.userptr = vb->baddr;
 333                 b->length    = vb->bsize;
 334                 break;
 335         case V4L2_MEMORY_OVERLAY:
 336                 b->m.offset  = vb->boff;
 337                 break;
 338         case V4L2_MEMORY_DMABUF:
 339                 /* DMABUF is not handled in videobuf framework */
 340                 break;
 341         }
 342
 343         b->flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
 344         if (vb->map)
 345                 b->flags |= V4L2_BUF_FLAG_MAPPED;
 346
 347         switch (vb->state) {
 348         case VIDEOBUF_PREPARED:
 349         case VIDEOBUF_QUEUED:
 350         case VIDEOBUF_ACTIVE:
 351                 b->flags |= V4L2_BUF_FLAG_QUEUED;
 352                 break;
 353         case VIDEOBUF_ERROR:
 354                 b->flags |= V4L2_BUF_FLAG_ERROR;
 355                 /* fall through */
 356         case VIDEOBUF_DONE:
 357                 b->flags |= V4L2_BUF_FLAG_DONE;
 358                 break;
 359         case VIDEOBUF_NEEDS_INIT:
 360         case VIDEOBUF_IDLE:
 361                 /* nothing */
 362                 break;
 363         }
 364
 365         b->field     = vb->field;
 366         b->timestamp = vb->ts;
 367         b->bytesused = vb->size;
 368         b->sequence  = vb->field_count >> 1;
 369 }
 370
 371 int videobuf_mmap_free(struct videobuf_queue *q)
 372 {
 373         int ret;
 374         videobuf_queue_lock(q);
 375         ret = __videobuf_free(q);
 376         videobuf_queue_unlock(q);
 377         return ret;
 378 }
 379 EXPORT_SYMBOL_GPL(videobuf_mmap_free);
 380
 381 /* Locking: Caller holds q->vb_lock */
 382 int __videobuf_mmap_setup(struct videobuf_queue *q,
 383                         unsigned int bcount, unsigned int bsize,
 384                         enum v4l2_memory memory)
 385 {
 386         unsigned int i;
 387         int err;
 388
 389         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 390
 391         err = __videobuf_free(q);
 392         if (0 != err)
 393                 return err;
 394
 395         /* Allocate and initialize buffers */
 396         for (i = 0; i < bcount; i++) {
 397                 q->bufs[i] = videobuf_alloc_vb(q);
 398
 399                 if (NULL == q->bufs[i])
 400                         break;
 401
 402                 q->bufs[i]->i      = i;
 403                 q->bufs[i]->memory = memory;
 404                 q->bufs[i]->bsize  = bsize;
 405                 switch (memory) {
 406                 case V4L2_MEMORY_MMAP:
 407                         q->bufs[i]->boff = PAGE_ALIGN(bsize) * i;
 408                         break;
 409                 case V4L2_MEMORY_USERPTR:
 410                 case V4L2_MEMORY_OVERLAY:
 411                 case V4L2_MEMORY_DMABUF:
 412                         /* nothing */
 413                         break;
 414                 }
 415         }
 416
 417         if (!i)
 418                 return -ENOMEM;
 419
 420         dprintk(1, "mmap setup: %d buffers, %d bytes each\n", i, bsize);
 421
 422         return i;
 423 }
 424 EXPORT_SYMBOL_GPL(__videobuf_mmap_setup);
 425
 426 int videobuf_mmap_setup(struct videobuf_queue *q,
 427                         unsigned int bcount, unsigned int bsize,
 428                         enum v4l2_memory memory)
 429 {
 430         int ret;
 431         videobuf_queue_lock(q);
 432         ret = __videobuf_mmap_setup(q, bcount, bsize, memory);
 433         videobuf_queue_unlock(q);
 434         return ret;
 435 }
 436 EXPORT_SYMBOL_GPL(videobuf_mmap_setup);
 437
 438 int videobuf_reqbufs(struct videobuf_queue *q,
 439                  struct v4l2_requestbuffers *req)
 440 {
 441         unsigned int size, count;
 442         int retval;
 443
 444         if (req->memory != V4L2_MEMORY_MMAP     &&
 445             req->memory != V4L2_MEMORY_USERPTR  &&
 446             req->memory != V4L2_MEMORY_OVERLAY) {
 447                 dprintk(1, "reqbufs: memory type invalid\n");
 448                 return -EINVAL;
 449         }
 450
 451         videobuf_queue_lock(q);
 452         if (req->type != q->type) {
 453                 dprintk(1, "reqbufs: queue type invalid\n");
 454                 retval = -EINVAL;
 455                 goto done;
 456         }
 457
 458         if (q->streaming) {
 459                 dprintk(1, "reqbufs: streaming already exists\n");
 460                 retval = -EBUSY;
 461                 goto done;
 462         }
 463         if (!list_empty(&q->stream)) {
 464                 dprintk(1, "reqbufs: stream running\n");
 465                 retval = -EBUSY;
 466                 goto done;
 467         }
 468
 469         if (req->count == 0) {
 470                 dprintk(1, "reqbufs: count invalid (%d)\n", req->count);
 471                 retval = __videobuf_free(q);
 472                 goto done;
 473         }
 474
 475         count = req->count;
 476         if (count > VIDEO_MAX_FRAME)
 477                 count = VIDEO_MAX_FRAME;
 478         size = 0;
 479         q->ops->buf_setup(q, &count, &size);
 480         dprintk(1, "reqbufs: bufs=%d, size=0x%x [%u pages total]\n",
 481                 count, size,
 482                 (unsigned int)((count * PAGE_ALIGN(size)) >> PAGE_SHIFT));
 483
 484         retval = __videobuf_mmap_setup(q, count, size, req->memory);
 485         if (retval < 0) {
 486                 dprintk(1, "reqbufs: mmap setup returned %d\n", retval);
 487                 goto done;
 488         }
 489
 490         req->count = retval;
 491         retval = 0;
 492
 493  done:
 494         videobuf_queue_unlock(q);
 495         return retval;
 496 }
 497 EXPORT_SYMBOL_GPL(videobuf_reqbufs);
 498
 499 int videobuf_querybuf(struct videobuf_queue *q, struct v4l2_buffer *b)
 500 {
 501         int ret = -EINVAL;
 502
 503         videobuf_queue_lock(q);
 504         if (unlikely(b->type != q->type)) {
 505                 dprintk(1, "querybuf: Wrong type.\n");
 506                 goto done;
 507         }
 508         if (unlikely(b->index >= VIDEO_MAX_FRAME)) {
 509                 dprintk(1, "querybuf: index out of range.\n");
 510                 goto done;
 511         }
 512         if (unlikely(NULL == q->bufs[b->index])) {
 513                 dprintk(1, "querybuf: buffer is null.\n");
 514                 goto done;
 515         }
 516
 517         videobuf_status(q, b, q->bufs[b->index], q->type);
 518
 519         ret = 0;
 520 done:
 521         videobuf_queue_unlock(q);
 522         return ret;
 523 }
 524 EXPORT_SYMBOL_GPL(videobuf_querybuf);
 525
 526 int videobuf_qbuf(struct videobuf_queue *q, struct v4l2_buffer *b)
 527 {
 528         struct videobuf_buffer *buf;
 529         enum v4l2_field field;
 530         unsigned long flags = 0;
 531         int retval;
 532
 533         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 534
 535         if (b->memory == V4L2_MEMORY_MMAP)
 536                 down_read(&current->mm->mmap_sem);
 537
 538         videobuf_queue_lock(q);
 539         retval = -EBUSY;
 540         if (q->reading) {
 541                 dprintk(1, "qbuf: Reading running...\n");
 542                 goto done;
 543         }
 544         retval = -EINVAL;
 545         if (b->type != q->type) {
 546                 dprintk(1, "qbuf: Wrong type.\n");
 547                 goto done;
 548         }
 549         if (b->index >= VIDEO_MAX_FRAME) {
 550                 dprintk(1, "qbuf: index out of range.\n");
 551                 goto done;
 552         }
 553         buf = q->bufs[b->index];
 554         if (NULL == buf) {
 555                 dprintk(1, "qbuf: buffer is null.\n");
 556                 goto done;
 557         }
 558         MAGIC_CHECK(buf->magic, MAGIC_BUFFER);
 559         if (buf->memory != b->memory) {
 560                 dprintk(1, "qbuf: memory type is wrong.\n");
 561                 goto done;
 562         }
 563         if (buf->state != VIDEOBUF_NEEDS_INIT && buf->state != VIDEOBUF_IDLE) {
 564                 dprintk(1, "qbuf: buffer is already queued or active.\n");
 565                 goto done;
 566         }
 567
 568         switch (b->memory) {
 569         case V4L2_MEMORY_MMAP:
 570                 if (0 == buf->baddr) {
 571                         dprintk(1, "qbuf: mmap requested "
 572                                    "but buffer addr is zero!\n");
 573                         goto done;
 574                 }
 575                 if (q->type == V4L2_BUF_TYPE_VIDEO_OUTPUT
 576                     || q->type == V4L2_BUF_TYPE_VBI_OUTPUT
 577                     || q->type == V4L2_BUF_TYPE_SLICED_VBI_OUTPUT) {
 578                         buf->size = b->bytesused;
 579                         buf->field = b->field;
 580                         buf->ts = b->timestamp;
 581                 }
 582                 break;
 583         case V4L2_MEMORY_USERPTR:
 584                 if (b->length < buf->bsize) {
 585                         dprintk(1, "qbuf: buffer length is not enough\n");
 586                         goto done;
 587                 }
 588                 if (VIDEOBUF_NEEDS_INIT != buf->state &&
 589                     buf->baddr != b->m.userptr)
 590                         q->ops->buf_release(q, buf);
 591                 buf->baddr = b->m.userptr;
 592                 break;
 593         case V4L2_MEMORY_OVERLAY:
 594                 buf->boff = b->m.offset;
 595                 break;
 596         default:
 597                 dprintk(1, "qbuf: wrong memory type\n");
 598                 goto done;
 599         }
 600
 601         dprintk(1, "qbuf: requesting next field\n");
 602         field = videobuf_next_field(q);
 603         retval = q->ops->buf_prepare(q, buf, field);
 604         if (0 != retval) {
 605                 dprintk(1, "qbuf: buffer_prepare returned %d\n", retval);
 606                 goto done;
 607         }
 608
 609         list_add_tail(&buf->stream, &q->stream);
 610         if (q->streaming) {
 611                 spin_lock_irqsave(q->irqlock, flags);
 612                 q->ops->buf_queue(q, buf);
 613                 spin_unlock_irqrestore(q->irqlock, flags);
 614         }
 615         dprintk(1, "qbuf: succeeded\n");
 616         retval = 0;
 617         wake_up_interruptible_sync(&q->wait);
 618
 619 done:
 620         videobuf_queue_unlock(q);
 621
 622         if (b->memory == V4L2_MEMORY_MMAP)
 623                 up_read(&current->mm->mmap_sem);
 624
 625         return retval;
 626 }
 627 EXPORT_SYMBOL_GPL(videobuf_qbuf);
 628
 629 /* Locking: Caller holds q->vb_lock */
 630 static int stream_next_buffer_check_queue(struct videobuf_queue *q, int noblock)
 631 {
 632         int retval;
 633
 634 checks:
 635         if (!q->streaming) {
 636                 dprintk(1, "next_buffer: Not streaming\n");
 637                 retval = -EINVAL;
 638                 goto done;
 639         }
 640
 641         if (list_empty(&q->stream)) {
 642                 if (noblock) {
 643                         retval = -EAGAIN;
 644                         dprintk(2, "next_buffer: no buffers to dequeue\n");
 645                         goto done;
 646                 } else {
 647                         dprintk(2, "next_buffer: waiting on buffer\n");
 648
 649                         /* Drop lock to avoid deadlock with qbuf */
 650                         videobuf_queue_unlock(q);
 651
 652                         /* Checking list_empty and streaming is safe without
 653                          * locks because we goto checks to validate while
 654                          * holding locks before proceeding */
 655                         retval = wait_event_interruptible(q->wait,
 656                                 !list_empty(&q->stream) || !q->streaming);
 657                         videobuf_queue_lock(q);
 658
 659                         if (retval)
 660                                 goto done;
 661
 662                         goto checks;
 663                 }
 664         }
 665
 666         retval = 0;
 667
 668 done:
 669         return retval;
 670 }
 671
 672 /* Locking: Caller holds q->vb_lock */
 673 static int stream_next_buffer(struct videobuf_queue *q,
 674                         struct videobuf_buffer **vb, int nonblocking)
 675 {
 676         int retval;
 677         struct videobuf_buffer *buf = NULL;
 678
 679         retval = stream_next_buffer_check_queue(q, nonblocking);
 680         if (retval)
 681                 goto done;
 682
 683         buf = list_entry(q->stream.next, struct videobuf_buffer, stream);
 684         retval = videobuf_waiton(q, buf, nonblocking, 1);
 685         if (retval < 0)
 686                 goto done;
 687
 688         *vb = buf;
 689 done:
 690         return retval;
 691 }
 692
 693 int videobuf_dqbuf(struct videobuf_queue *q,
 694                    struct v4l2_buffer *b, int nonblocking)
 695 {
 696         struct videobuf_buffer *buf = NULL;
 697         int retval;
 698
 699         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 700
 701         memset(b, 0, sizeof(*b));
 702         videobuf_queue_lock(q);
 703
 704         retval = stream_next_buffer(q, &buf, nonblocking);
 705         if (retval < 0) {
 706                 dprintk(1, "dqbuf: next_buffer error: %i\n", retval);
 707                 goto done;
 708         }
 709
 710         switch (buf->state) {
 711         case VIDEOBUF_ERROR:
 712                 dprintk(1, "dqbuf: state is error\n");
 713                 break;
 714         case VIDEOBUF_DONE:
 715                 dprintk(1, "dqbuf: state is done\n");
 716                 break;
 717         default:
 718                 dprintk(1, "dqbuf: state invalid\n");
 719                 retval = -EINVAL;
 720                 goto done;
 721         }
 722         CALL(q, sync, q, buf);
 723         videobuf_status(q, b, buf, q->type);
 724         list_del(&buf->stream);
 725         buf->state = VIDEOBUF_IDLE;
 726         b->flags &= ~V4L2_BUF_FLAG_DONE;
 727 done:
 728         videobuf_queue_unlock(q);
 729         return retval;
 730 }
 731 EXPORT_SYMBOL_GPL(videobuf_dqbuf);
 732
 733 int videobuf_streamon(struct videobuf_queue *q)
 734 {
 735         struct videobuf_buffer *buf;
 736         unsigned long flags = 0;
 737         int retval;
 738
 739         videobuf_queue_lock(q);
 740         retval = -EBUSY;
 741         if (q->reading)
 742                 goto done;
 743         retval = 0;
 744         if (q->streaming)
 745                 goto done;
 746         q->streaming = 1;
 747         spin_lock_irqsave(q->irqlock, flags);
 748         list_for_each_entry(buf, &q->stream, stream)
 749                 if (buf->state == VIDEOBUF_PREPARED)
 750                         q->ops->buf_queue(q, buf);
 751         spin_unlock_irqrestore(q->irqlock, flags);
 752
 753         wake_up_interruptible_sync(&q->wait);
 754 done:
 755         videobuf_queue_unlock(q);
 756         return retval;
 757 }
 758 EXPORT_SYMBOL_GPL(videobuf_streamon);
 759
 760 /* Locking: Caller holds q->vb_lock */
 761 static int __videobuf_streamoff(struct videobuf_queue *q)
 762 {
 763         if (!q->streaming)
 764                 return -EINVAL;
 765
 766         videobuf_queue_cancel(q);
 767
 768         return 0;
 769 }
 770
 771 int videobuf_streamoff(struct videobuf_queue *q)
 772 {
 773         int retval;
 774
 775         videobuf_queue_lock(q);
 776         retval = __videobuf_streamoff(q);
 777         videobuf_queue_unlock(q);
 778
 779         return retval;
 780 }
 781 EXPORT_SYMBOL_GPL(videobuf_streamoff);
 782
 783 /* Locking: Caller holds q->vb_lock */
 784 static ssize_t videobuf_read_zerocopy(struct videobuf_queue *q,
 785                                       char __user *data,
 786                                       size_t count, loff_t *ppos)
 787 {
 788         enum v4l2_field field;
 789         unsigned long flags = 0;
 790         int retval;
 791
 792         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 793
 794         /* setup stuff */
 795         q->read_buf = videobuf_alloc_vb(q);
 796         if (NULL == q->read_buf)
 797                 return -ENOMEM;
 798
 799         q->read_buf->memory = V4L2_MEMORY_USERPTR;
 800         q->read_buf->baddr  = (unsigned long)data;
 801         q->read_buf->bsize  = count;
 802
 803         field = videobuf_next_field(q);
 804         retval = q->ops->buf_prepare(q, q->read_buf, field);
 805         if (0 != retval)
 806                 goto done;
 807
 808         /* start capture & wait */
 809         spin_lock_irqsave(q->irqlock, flags);
 810         q->ops->buf_queue(q, q->read_buf);
 811         spin_unlock_irqrestore(q->irqlock, flags);
 812         retval = videobuf_waiton(q, q->read_buf, 0, 0);
 813         if (0 == retval) {
 814                 CALL(q, sync, q, q->read_buf);
 815                 if (VIDEOBUF_ERROR == q->read_buf->state)
 816                         retval = -EIO;
 817                 else
 818                         retval = q->read_buf->size;
 819         }
 820
 821 done:
 822         /* cleanup */
 823         q->ops->buf_release(q, q->read_buf);
 824         kfree(q->read_buf);
 825         q->read_buf = NULL;
 826         return retval;
 827 }
 828
 829 static int __videobuf_copy_to_user(struct videobuf_queue *q,
 830                                    struct videobuf_buffer *buf,
 831                                    char __user *data, size_t count,
 832                                    int nonblocking)
 833 {
 834         void *vaddr = CALL(q, vaddr, buf);
 835
 836         /* copy to userspace */
 837         if (count > buf->size - q->read_off)
 838                 count = buf->size - q->read_off;
 839
 840         if (copy_to_user(data, vaddr + q->read_off, count))
 841                 return -EFAULT;
 842
 843         return count;
 844 }
 845
 846 static int __videobuf_copy_stream(struct videobuf_queue *q,
 847                                   struct videobuf_buffer *buf,
 848                                   char __user *data, size_t count, size_t pos,
 849                                   int vbihack, int nonblocking)
 850 {
 851         unsigned int *fc = CALL(q, vaddr, buf);
 852
 853         if (vbihack) {
 854                 /* dirty, undocumented hack -- pass the frame counter
 855                         * within the last four bytes of each vbi data block.
 856                         * We need that one to maintain backward compatibility
 857                         * to all vbi decoding software out there ... */
 858                 fc += (buf->size >> 2) - 1;
 859                 *fc = buf->field_count >> 1;
 860                 dprintk(1, "vbihack: %d\n", *fc);
 861         }
 862
 863         /* copy stuff using the common method */
 864         count = __videobuf_copy_to_user(q, buf, data, count, nonblocking);
 865
 866         if ((count == -EFAULT) && (pos == 0))
 867                 return -EFAULT;
 868
 869         return count;
 870 }
 871
 872 ssize_t videobuf_read_one(struct videobuf_queue *q,
 873                           char __user *data, size_t count, loff_t *ppos,
 874                           int nonblocking)
 875 {
 876         enum v4l2_field field;
 877         unsigned long flags = 0;
 878         unsigned size = 0, nbufs = 1;
 879         int retval;
 880
 881         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
 882
 883         videobuf_queue_lock(q);
 884
 885         q->ops->buf_setup(q, &nbufs, &size);
 886
 887         if (NULL == q->read_buf  &&
 888             count >= size        &&
 889             !nonblocking) {
 890                 retval = videobuf_read_zerocopy(q, data, count, ppos);
 891                 if (retval >= 0  ||  retval == -EIO)
 892                         /* ok, all done */
 893                         goto done;
 894                 /* fallback to kernel bounce buffer on failures */
 895         }
 896
 897         if (NULL == q->read_buf) {
 898                 /* need to capture a new frame */
 899                 retval = -ENOMEM;
 900                 q->read_buf = videobuf_alloc_vb(q);
 901
 902                 dprintk(1, "video alloc=0x%p\n", q->read_buf);
 903                 if (NULL == q->read_buf)
 904                         goto done;
 905                 q->read_buf->memory = V4L2_MEMORY_USERPTR;
 906                 q->read_buf->bsize = count; /* preferred size */
 907                 field = videobuf_next_field(q);
 908                 retval = q->ops->buf_prepare(q, q->read_buf, field);
 909
 910                 if (0 != retval) {
 911                         kfree(q->read_buf);
 912                         q->read_buf = NULL;
 913                         goto done;
 914                 }
 915
 916                 spin_lock_irqsave(q->irqlock, flags);
 917                 q->ops->buf_queue(q, q->read_buf);
 918                 spin_unlock_irqrestore(q->irqlock, flags);
 919
 920                 q->read_off = 0;
 921         }
 922
 923         /* wait until capture is done */
 924         retval = videobuf_waiton(q, q->read_buf, nonblocking, 1);
 925         if (0 != retval)
 926                 goto done;
 927
 928         CALL(q, sync, q, q->read_buf);
 929
 930         if (VIDEOBUF_ERROR == q->read_buf->state) {
 931                 /* catch I/O errors */
 932                 q->ops->buf_release(q, q->read_buf);
 933                 kfree(q->read_buf);
 934                 q->read_buf = NULL;
 935                 retval = -EIO;
 936                 goto done;
 937         }
 938
 939         /* Copy to userspace */
 940         retval = __videobuf_copy_to_user(q, q->read_buf, data, count, nonblocking);
 941         if (retval < 0)
 942                 goto done;
 943
 944         q->read_off += retval;
 945         if (q->read_off == q->read_buf->size) {
 946                 /* all data copied, cleanup */
 947                 q->ops->buf_release(q, q->read_buf);
 948                 kfree(q->read_buf);
 949                 q->read_buf = NULL;
 950         }
 951
 952 done:
 953         videobuf_queue_unlock(q);
 954         return retval;
 955 }
 956 EXPORT_SYMBOL_GPL(videobuf_read_one);
 957
 958 /* Locking: Caller holds q->vb_lock */
 959 static int __videobuf_read_start(struct videobuf_queue *q)
 960 {
 961         enum v4l2_field field;
 962         unsigned long flags = 0;
 963         unsigned int count = 0, size = 0;
 964         int err, i;
 965
 966         q->ops->buf_setup(q, &count, &size);
 967         if (count < 2)
 968                 count = 2;
 969         if (count > VIDEO_MAX_FRAME)
 970                 count = VIDEO_MAX_FRAME;
 971         size = PAGE_ALIGN(size);
 972
 973         err = __videobuf_mmap_setup(q, count, size, V4L2_MEMORY_USERPTR);
 974         if (err < 0)
 975                 return err;
 976
 977         count = err;
 978
 979         for (i = 0; i < count; i++) {
 980                 field = videobuf_next_field(q);
 981                 err = q->ops->buf_prepare(q, q->bufs[i], field);
 982                 if (err)
 983                         return err;
 984                 list_add_tail(&q->bufs[i]->stream, &q->stream);
 985         }
 986         spin_lock_irqsave(q->irqlock, flags);
 987         for (i = 0; i < count; i++)
 988                 q->ops->buf_queue(q, q->bufs[i]);
 989         spin_unlock_irqrestore(q->irqlock, flags);
 990         q->reading = 1;
 991         return 0;
 992 }
 993
 994 static void __videobuf_read_stop(struct videobuf_queue *q)
 995 {
 996         int i;
 997
 998         videobuf_queue_cancel(q);
 999         __videobuf_free(q);
1000         INIT_LIST_HEAD(&q->stream);
1001         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
1002                 if (NULL == q->bufs[i])
1003                         continue;
1004                 kfree(q->bufs[i]);
1005                 q->bufs[i] = NULL;
1006         }
1007         q->read_buf = NULL;
1008 }
1009
1010 int videobuf_read_start(struct videobuf_queue *q)
1011 {
1012         int rc;
1013
1014         videobuf_queue_lock(q);
1015         rc = __videobuf_read_start(q);
1016         videobuf_queue_unlock(q);
1017
1018         return rc;
1019 }
1020 EXPORT_SYMBOL_GPL(videobuf_read_start);
1021
1022 void videobuf_read_stop(struct videobuf_queue *q)
1023 {
1024         videobuf_queue_lock(q);
1025         __videobuf_read_stop(q);
1026         videobuf_queue_unlock(q);
1027 }
1028 EXPORT_SYMBOL_GPL(videobuf_read_stop);
1029
1030 void videobuf_stop(struct videobuf_queue *q)
1031 {
1032         videobuf_queue_lock(q);
1033
1034         if (q->streaming)
1035                 __videobuf_streamoff(q);
1036
1037         if (q->reading)
1038                 __videobuf_read_stop(q);
1039
1040         videobuf_queue_unlock(q);
1041 }
1042 EXPORT_SYMBOL_GPL(videobuf_stop);
1043
1044 ssize_t videobuf_read_stream(struct videobuf_queue *q,
1045                              char __user *data, size_t count, loff_t *ppos,
1046                              int vbihack, int nonblocking)
1047 {
1048         int rc, retval;
1049         unsigned long flags = 0;
1050
1051         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
1052
1053         dprintk(2, "%s\n", __func__);
1054         videobuf_queue_lock(q);
1055         retval = -EBUSY;
1056         if (q->streaming)
1057                 goto done;
1058         if (!q->reading) {
1059                 retval = __videobuf_read_start(q);
1060                 if (retval < 0)
1061                         goto done;
1062         }
1063
1064         retval = 0;
1065         while (count > 0) {
1066                 /* get / wait for data */
1067                 if (NULL == q->read_buf) {
1068                         q->read_buf = list_entry(q->stream.next,
1069                                                  struct videobuf_buffer,
1070                                                  stream);
1071                         list_del(&q->read_buf->stream);
1072                         q->read_off = 0;
1073                 }
1074                 rc = videobuf_waiton(q, q->read_buf, nonblocking, 1);
1075                 if (rc < 0) {
1076                         if (0 == retval)
1077                                 retval = rc;
1078                         break;
1079                 }
1080
1081                 if (q->read_buf->state == VIDEOBUF_DONE) {
1082                         rc = __videobuf_copy_stream(q, q->read_buf, data + retval, count,
1083                                         retval, vbihack, nonblocking);
1084                         if (rc < 0) {
1085                                 retval = rc;
1086                                 break;
1087                         }
1088                         retval      += rc;
1089                         count       -= rc;
1090                         q->read_off += rc;
1091                 } else {
1092                         /* some error */
1093                         q->read_off = q->read_buf->size;
1094                         if (0 == retval)
1095                                 retval = -EIO;
1096                 }
1097
1098                 /* requeue buffer when done with copying */
1099                 if (q->read_off == q->read_buf->size) {
1100                         list_add_tail(&q->read_buf->stream,
1101                                       &q->stream);
1102                         spin_lock_irqsave(q->irqlock, flags);
1103                         q->ops->buf_queue(q, q->read_buf);
1104                         spin_unlock_irqrestore(q->irqlock, flags);
1105                         q->read_buf = NULL;
1106                 }
1107                 if (retval < 0)
1108                         break;
1109         }
1110
1111 done:
1112         videobuf_queue_unlock(q);
1113         return retval;
1114 }
1115 EXPORT_SYMBOL_GPL(videobuf_read_stream);
1116
1117 unsigned int videobuf_poll_stream(struct file *file,
1118                                   struct videobuf_queue *q,
1119                                   poll_table *wait)
1120 {
1121         unsigned long req_events = poll_requested_events(wait);
1122         struct videobuf_buffer *buf = NULL;
1123         unsigned int rc = 0;
1124
1125         videobuf_queue_lock(q);
1126         if (q->streaming) {
1127                 if (!list_empty(&q->stream))
1128                         buf = list_entry(q->stream.next,
1129                                          struct videobuf_buffer, stream);
1130         } else if (req_events & (POLLIN | POLLRDNORM)) {
1131                 if (!q->reading)
1132                         __videobuf_read_start(q);
1133                 if (!q->reading) {
1134                         rc = POLLERR;
1135                 } else if (NULL == q->read_buf) {
1136                         q->read_buf = list_entry(q->stream.next,
1137                                                  struct videobuf_buffer,
1138                                                  stream);
1139                         list_del(&q->read_buf->stream);
1140                         q->read_off = 0;
1141                 }
1142                 buf = q->read_buf;
1143         }
1144         if (!buf)
1145                 rc = POLLERR;
1146
1147         if (0 == rc) {
1148                 poll_wait(file, &buf->done, wait);
1149                 if (buf->state == VIDEOBUF_DONE ||
1150                     buf->state == VIDEOBUF_ERROR) {
1151                         switch (q->type) {
1152                         case V4L2_BUF_TYPE_VIDEO_OUTPUT:
1153                         case V4L2_BUF_TYPE_VBI_OUTPUT:
1154                         case V4L2_BUF_TYPE_SLICED_VBI_OUTPUT:
1155                                 rc = POLLOUT | POLLWRNORM;
1156                                 break;
1157                         default:
1158                                 rc = POLLIN | POLLRDNORM;
1159                                 break;
1160                         }
1161                 }
1162         }
1163         videobuf_queue_unlock(q);
1164         return rc;
1165 }
1166 EXPORT_SYMBOL_GPL(videobuf_poll_stream);
1167
1168 int videobuf_mmap_mapper(struct videobuf_queue *q, struct vm_area_struct *vma)
1169 {
1170         int rc = -EINVAL;
1171         int i;
1172
1173         MAGIC_CHECK(q->int_ops->magic, MAGIC_QTYPE_OPS);
1174
1175         if (!(vma->vm_flags & VM_WRITE) || !(vma->vm_flags & VM_SHARED)) {
1176                 dprintk(1, "mmap appl bug: PROT_WRITE and MAP_SHARED are required\n");
1177                 return -EINVAL;
1178         }
1179
1180         videobuf_queue_lock(q);
1181         for (i = 0; i < VIDEO_MAX_FRAME; i++) {
1182                 struct videobuf_buffer *buf = q->bufs[i];
1183
1184                 if (buf && buf->memory == V4L2_MEMORY_MMAP &&
1185                                 buf->boff == (vma->vm_pgoff << PAGE_SHIFT)) {
1186                         rc = CALL(q, mmap_mapper, q, buf, vma);
1187                         break;
1188                 }
1189         }
1190         videobuf_queue_unlock(q);
1191
1192         return rc;
1193 }
1194 EXPORT_SYMBOL_GPL(videobuf_mmap_mapper);