drivers/media/video/vivi.c

   1 /*
   2  * Virtual Video driver - This code emulates a real video device with v4l2 api
   3  *
   4  * Copyright (c) 2006 by:
   5  *      Mauro Carvalho Chehab <mchehab--a.t--infradead.org>
   6  *      Ted Walther <ted--a.t--enumera.com>
   7  *      John Sokol <sokol--a.t--videotechnology.com>
   8  *      http://v4l.videotechnology.com/
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the BSD Licence, GNU General Public License
  12  * as published by the Free Software Foundation; either version 2 of the
  13  * License, or (at your option) any later version
  14  */
  15 #include <linux/module.h>
  16 #include <linux/delay.h>
  17 #include <linux/errno.h>
  18 #include <linux/fs.h>
  19 #include <linux/kernel.h>
  20 #include <linux/slab.h>
  21 #include <linux/mm.h>
  22 #include <linux/ioport.h>
  23 #include <linux/init.h>
  24 #include <linux/sched.h>
  25 #include <linux/pci.h>
  26 #include <linux/random.h>
  27 #include <linux/version.h>
  28 #include <linux/mutex.h>
  29 #include <linux/videodev2.h>
  30 #include <linux/dma-mapping.h>
  31 #ifdef CONFIG_VIDEO_V4L1_COMPAT
  32 /* Include V4L1 specific functions. Should be removed soon */
  33 #include <linux/videodev.h>
  34 #endif
  35 #include <linux/interrupt.h>
  36 #include <media/videobuf-vmalloc.h>
  37 #include <media/v4l2-common.h>
  38 #include <linux/kthread.h>
  39 #include <linux/highmem.h>
  40 #include <linux/freezer.h>
  41
  42 /* Wake up at about 30 fps */
  43 #define WAKE_NUMERATOR 30
  44 #define WAKE_DENOMINATOR 1001
  45 #define BUFFER_TIMEOUT     msecs_to_jiffies(500)  /* 0.5 seconds */
  46
  47 #include "font.h"
  48
  49 #define VIVI_MAJOR_VERSION 0
  50 #define VIVI_MINOR_VERSION 4
  51 #define VIVI_RELEASE 0
  52 #define VIVI_VERSION \
  53         KERNEL_VERSION(VIVI_MAJOR_VERSION, VIVI_MINOR_VERSION, VIVI_RELEASE)
  54
  55 /* Declare static vars that will be used as parameters */
  56 static unsigned int vid_limit = 16;     /* Video memory limit, in Mb */
  57 static int video_nr = -1;               /* /dev/videoN, -1 for autodetect */
  58 static int n_devs = 1;                  /* Number of virtual devices */
  59
  60 /* supported controls */
  61 static struct v4l2_queryctrl vivi_qctrl[] = {
  62         {
  63                 .id            = V4L2_CID_AUDIO_VOLUME,
  64                 .name          = "Volume",
  65                 .minimum       = 0,
  66                 .maximum       = 65535,
  67                 .step          = 65535/100,
  68                 .default_value = 65535,
  69                 .flags         = 0,
  70                 .type          = V4L2_CTRL_TYPE_INTEGER,
  71         }, {
  72                 .id            = V4L2_CID_BRIGHTNESS,
  73                 .type          = V4L2_CTRL_TYPE_INTEGER,
  74                 .name          = "Brightness",
  75                 .minimum       = 0,
  76                 .maximum       = 255,
  77                 .step          = 1,
  78                 .default_value = 127,
  79                 .flags         = 0,
  80         }, {
  81                 .id            = V4L2_CID_CONTRAST,
  82                 .type          = V4L2_CTRL_TYPE_INTEGER,
  83                 .name          = "Contrast",
  84                 .minimum       = 0,
  85                 .maximum       = 255,
  86                 .step          = 0x1,
  87                 .default_value = 0x10,
  88                 .flags         = 0,
  89         }, {
  90                 .id            = V4L2_CID_SATURATION,
  91                 .type          = V4L2_CTRL_TYPE_INTEGER,
  92                 .name          = "Saturation",
  93                 .minimum       = 0,
  94                 .maximum       = 255,
  95                 .step          = 0x1,
  96                 .default_value = 127,
  97                 .flags         = 0,
  98         }, {
  99                 .id            = V4L2_CID_HUE,
 100                 .type          = V4L2_CTRL_TYPE_INTEGER,
 101                 .name          = "Hue",
 102                 .minimum       = -128,
 103                 .maximum       = 127,
 104                 .step          = 0x1,
 105                 .default_value = 0,
 106                 .flags         = 0,
 107         }
 108 };
 109
 110 static int qctl_regs[ARRAY_SIZE(vivi_qctrl)];
 111
 112 #define dprintk(dev, level, fmt, arg...)                                \
 113         do {                                                            \
 114                 if (dev->vfd->debug >= (level))                         \
 115                         printk(KERN_DEBUG "vivi: " fmt , ## arg);       \
 116         } while (0)
 117
 118 /* ------------------------------------------------------------------
 119         Basic structures
 120    ------------------------------------------------------------------*/
 121
 122 struct vivi_fmt {
 123         char  *name;
 124         u32   fourcc;          /* v4l2 format id */
 125         int   depth;
 126 };
 127
 128 static struct vivi_fmt format = {
 129         .name     = "4:2:2, packed, YUYV",
 130         .fourcc   = V4L2_PIX_FMT_YUYV,
 131         .depth    = 16,
 132 };
 133
 134 struct sg_to_addr {
 135         int pos;
 136         struct scatterlist *sg;
 137 };
 138
 139 /* buffer for one video frame */
 140 struct vivi_buffer {
 141         /* common v4l buffer stuff -- must be first */
 142         struct videobuf_buffer vb;
 143
 144         struct vivi_fmt        *fmt;
 145 };
 146
 147 struct vivi_dmaqueue {
 148         struct list_head       active;
 149         struct list_head       queued;
 150         struct timer_list      timeout;
 151
 152         /* thread for generating video stream*/
 153         struct task_struct         *kthread;
 154         wait_queue_head_t          wq;
 155         /* Counters to control fps rate */
 156         int                        frame;
 157         int                        ini_jiffies;
 158 };
 159
 160 static LIST_HEAD(vivi_devlist);
 161
 162 struct vivi_dev {
 163         struct list_head           vivi_devlist;
 164
 165         struct mutex               lock;
 166         spinlock_t                 slock;
 167
 168         int                        users;
 169
 170         /* various device info */
 171         struct video_device        *vfd;
 172
 173         struct vivi_dmaqueue       vidq;
 174
 175         /* Several counters */
 176         int                        h, m, s, ms;
 177         unsigned long              jiffies;
 178         char                       timestr[13];
 179
 180         int                        mv_count;    /* Controls bars movement */
 181 };
 182
 183 struct vivi_fh {
 184         struct vivi_dev            *dev;
 185
 186         /* video capture */
 187         struct vivi_fmt            *fmt;
 188         unsigned int               width, height;
 189         struct videobuf_queue      vb_vidq;
 190
 191         enum v4l2_buf_type         type;
 192 };
 193
 194 /* ------------------------------------------------------------------
 195         DMA and thread functions
 196    ------------------------------------------------------------------*/
 197
 198 /* Bars and Colors should match positions */
 199
 200 enum colors {
 201         WHITE,
 202         AMBAR,
 203         CYAN,
 204         GREEN,
 205         MAGENTA,
 206         RED,
 207         BLUE,
 208         BLACK,
 209 };
 210
 211 static u8 bars[8][3] = {
 212         /* R   G   B */
 213         {204, 204, 204},  /* white */
 214         {208, 208,   0},  /* ambar */
 215         {  0, 206, 206},  /* cyan */
 216         {  0, 239,   0},  /* green */
 217         {239,   0, 239},  /* magenta */
 218         {205,   0,   0},  /* red */
 219         {  0,   0, 255},  /* blue */
 220         {  0,   0,   0},  /* black */
 221 };
 222
 223 #define TO_Y(r, g, b) \
 224         (((16829 * r + 33039 * g + 6416 * b  + 32768) >> 16) + 16)
 225 /* RGB to  V(Cr) Color transform */
 226 #define TO_V(r, g, b) \
 227         (((28784 * r - 24103 * g - 4681 * b  + 32768) >> 16) + 128)
 228 /* RGB to  U(Cb) Color transform */
 229 #define TO_U(r, g, b) \
 230         (((-9714 * r - 19070 * g + 28784 * b + 32768) >> 16) + 128)
 231
 232 #define TSTAMP_MIN_Y 24
 233 #define TSTAMP_MAX_Y TSTAMP_MIN_Y+15
 234 #define TSTAMP_MIN_X 64
 235
 236 static void gen_line(char *basep, int inipos, int wmax,
 237                 int hmax, int line, int count, char *timestr)
 238 {
 239         int  w, i, j, y;
 240         int pos = inipos;
 241         char *p, *s;
 242         u8   chr, r, g, b, color;
 243
 244         /* We will just duplicate the second pixel at the packet */
 245         wmax /= 2;
 246
 247         /* Generate a standard color bar pattern */
 248         for (w = 0; w < wmax; w++) {
 249                 int colorpos = ((w + count) * 8/(wmax + 1)) % 8;
 250                 r = bars[colorpos][0];
 251                 g = bars[colorpos][1];
 252                 b = bars[colorpos][2];
 253
 254                 for (color = 0; color < 4; color++) {
 255                         p = basep + pos;
 256
 257                         switch (color) {
 258                         case 0:
 259                         case 2:
 260                                 *p = TO_Y(r, g, b);     /* Luma */
 261                                 break;
 262                         case 1:
 263                                 *p = TO_U(r, g, b);     /* Cb */
 264                                 break;
 265                         case 3:
 266                                 *p = TO_V(r, g, b);     /* Cr */
 267                                 break;
 268                         }
 269                         pos++;
 270                 }
 271         }
 272
 273         /* Checks if it is possible to show timestamp */
 274         if (TSTAMP_MAX_Y >= hmax)
 275                 goto end;
 276         if (TSTAMP_MIN_X + strlen(timestr) >= wmax)
 277                 goto end;
 278
 279         /* Print stream time */
 280         if (line >= TSTAMP_MIN_Y && line <= TSTAMP_MAX_Y) {
 281                 j = TSTAMP_MIN_X;
 282                 for (s = timestr; *s; s++) {
 283                         chr = rom8x16_bits[(*s-0x30)*16+line-TSTAMP_MIN_Y];
 284                         for (i = 0; i < 7; i++) {
 285                                 if (chr & 1 << (7 - i)) {
 286                                         /* Font color*/
 287                                         r = 0;
 288                                         g = 198;
 289                                         b = 0;
 290                                 } else {
 291                                         /* Background color */
 292                                         r = bars[BLACK][0];
 293                                         g = bars[BLACK][1];
 294                                         b = bars[BLACK][2];
 295                                 }
 296
 297                                 pos = inipos + j * 2;
 298                                 for (color = 0; color < 4; color++) {
 299                                         p = basep + pos;
 300
 301                                         y = TO_Y(r, g, b);
 302
 303                                         switch (color) {
 304                                         case 0:
 305                                         case 2:
 306                                                 *p = TO_Y(r, g, b); /* Luma */
 307                                                 break;
 308                                         case 1:
 309                                                 *p = TO_U(r, g, b); /* Cb */
 310                                                 break;
 311                                         case 3:
 312                                                 *p = TO_V(r, g, b); /* Cr */
 313                                                 break;
 314                                         }
 315                                         pos++;
 316                                 }
 317                                 j++;
 318                         }
 319                 }
 320         }
 321
 322 end:
 323         return;
 324 }
 325 static void vivi_fillbuff(struct vivi_dev *dev, struct vivi_buffer *buf)
 326 {
 327         int h , pos = 0;
 328         int hmax  = buf->vb.height;
 329         int wmax  = buf->vb.width;
 330         struct timeval ts;
 331         char *tmpbuf = kmalloc(wmax * 2, GFP_KERNEL);
 332         void *vbuf = videobuf_to_vmalloc(&buf->vb);
 333
 334         if (!tmpbuf)
 335                 return;
 336
 337         for (h = 0; h < hmax; h++) {
 338                 gen_line(tmpbuf, 0, wmax, hmax, h, dev->mv_count,
 339                          dev->timestr);
 340                 /* FIXME: replacing to __copy_to_user */
 341                 if (copy_to_user(vbuf + pos, tmpbuf, wmax * 2) != 0)
 342                         dprintk(dev, 2, "vivifill copy_to_user failed.\n");
 343                 pos += wmax*2;
 344         }
 345
 346         dev->mv_count++;
 347
 348         kfree(tmpbuf);
 349
 350         /* Updates stream time */
 351
 352         dev->ms += jiffies_to_msecs(jiffies-dev->jiffies);
 353         dev->jiffies = jiffies;
 354         if (dev->ms >= 1000) {
 355                 dev->ms -= 1000;
 356                 dev->s++;
 357                 if (dev->s >= 60) {
 358                         dev->s -= 60;
 359                         dev->m++;
 360                         if (dev->m > 60) {
 361                                 dev->m -= 60;
 362                                 dev->h++;
 363                                 if (dev->h > 24)
 364                                         dev->h -= 24;
 365                         }
 366                 }
 367         }
 368         sprintf(dev->timestr, "%02d:%02d:%02d:%03d",
 369                         dev->h, dev->m, dev->s, dev->ms);
 370
 371         dprintk(dev, 2, "vivifill at %s: Buffer 0x%08lx size= %d\n",
 372                         dev->timestr, (unsigned long)tmpbuf, pos);
 373
 374         /* Advice that buffer was filled */
 375         buf->vb.state = VIDEOBUF_DONE;
 376         buf->vb.field_count++;
 377         do_gettimeofday(&ts);
 378         buf->vb.ts = ts;
 379
 380         list_del(&buf->vb.queue);
 381         wake_up(&buf->vb.done);
 382 }
 383
 384 static int restart_video_queue(struct vivi_dmaqueue *dma_q);
 385
 386 static void vivi_thread_tick(struct vivi_dmaqueue  *dma_q)
 387 {
 388         struct vivi_buffer    *buf;
 389         struct vivi_dev *dev = container_of(dma_q, struct vivi_dev, vidq);
 390
 391         int bc;
 392
 393         spin_lock(&dev->slock);
 394         /* Announces videobuf that all went ok */
 395         for (bc = 0;; bc++) {
 396                 if (list_empty(&dma_q->active)) {
 397                         dprintk(dev, 1, "No active queue to serve\n");
 398                         break;
 399                 }
 400
 401                 buf = list_entry(dma_q->active.next,
 402                                  struct vivi_buffer, vb.queue);
 403
 404                 /* Nobody is waiting something to be done, just return */
 405                 if (!waitqueue_active(&buf->vb.done)) {
 406                         mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
 407                         spin_unlock(&dev->slock);
 408                         return;
 409                 }
 410
 411                 do_gettimeofday(&buf->vb.ts);
 412                 dprintk(dev, 2, "[%p/%d] wakeup\n", buf, buf->vb. i);
 413
 414                 /* Fill buffer */
 415                 vivi_fillbuff(dev, buf);
 416
 417                 if (list_empty(&dma_q->active)) {
 418                         del_timer(&dma_q->timeout);
 419                 } else {
 420                         mod_timer(&dma_q->timeout, jiffies + BUFFER_TIMEOUT);
 421                 }
 422         }
 423         if (bc != 1)
 424                 dprintk(dev, 1, "%s: %d buffers handled (should be 1)\n",
 425                         __FUNCTION__, bc);
 426         spin_unlock(&dev->slock);
 427 }
 428
 429 #define frames_to_ms(frames)                                    \
 430         ((frames * WAKE_NUMERATOR * 1000) / WAKE_DENOMINATOR)
 431
 432 static void vivi_sleep(struct vivi_dmaqueue  *dma_q)
 433 {
 434         struct vivi_dev *dev = container_of(dma_q, struct vivi_dev, vidq);
 435         int timeout, running_time;
 436         DECLARE_WAITQUEUE(wait, current);
 437
 438         dprintk(dev, 1, "%s dma_q=0x%08lx\n", __FUNCTION__,
 439                 (unsigned long)dma_q);
 440
 441         add_wait_queue(&dma_q->wq, &wait);
 442         if (kthread_should_stop())
 443                 goto stop_task;
 444
 445         running_time = jiffies - dma_q->ini_jiffies;
 446         dma_q->frame++;
 447
 448         /* Calculate time to wake up */
 449         timeout = msecs_to_jiffies(frames_to_ms(dma_q->frame)) - running_time;
 450
 451         if (timeout > msecs_to_jiffies(frames_to_ms(2)) || timeout <= 0) {
 452                 int old = dma_q->frame;
 453                 int nframes;
 454
 455                 dma_q->frame = (jiffies_to_msecs(running_time) /
 456                                frames_to_ms(1)) + 1;
 457
 458                 timeout = msecs_to_jiffies(frames_to_ms(dma_q->frame))
 459                           - running_time;
 460
 461                 if (unlikely (timeout <= 0))
 462                         timeout = 1;
 463
 464                 nframes = (dma_q->frame > old)?
 465                                   dma_q->frame - old : old - dma_q->frame;
 466
 467                 dprintk(dev, 1, "%ld: %s %d frames. "
 468                         "Current frame is %d. Will sleep for %d jiffies\n",
 469                         jiffies,
 470                         (dma_q->frame > old)? "Underrun, losed" : "Overrun of",
 471                         nframes, dma_q->frame, timeout);
 472         } else
 473                 dprintk(dev, 1, "will sleep for %d jiffies\n", timeout);
 474
 475         vivi_thread_tick(dma_q);
 476
 477         schedule_timeout_interruptible(timeout);
 478
 479 stop_task:
 480         remove_wait_queue(&dma_q->wq, &wait);
 481         try_to_freeze();
 482 }
 483
 484 static int vivi_thread(void *data)
 485 {
 486         struct vivi_dmaqueue  *dma_q = data;
 487         struct vivi_dev *dev = container_of(dma_q, struct vivi_dev, vidq);
 488
 489         dprintk(dev, 1, "thread started\n");
 490
 491         mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
 492         set_freezable();
 493
 494         for (;;) {
 495                 vivi_sleep(dma_q);
 496
 497                 if (kthread_should_stop())
 498                         break;
 499         }
 500         dprintk(dev, 1, "thread: exit\n");
 501         return 0;
 502 }
 503
 504 static int vivi_start_thread(struct vivi_dmaqueue  *dma_q)
 505 {
 506         struct vivi_dev *dev = container_of(dma_q, struct vivi_dev, vidq);
 507
 508         dma_q->frame = 0;
 509         dma_q->ini_jiffies = jiffies;
 510
 511         dprintk(dev, 1, "%s\n", __FUNCTION__);
 512
 513         dma_q->kthread = kthread_run(vivi_thread, dma_q, "vivi");
 514
 515         if (IS_ERR(dma_q->kthread)) {
 516                 printk(KERN_ERR "vivi: kernel_thread() failed\n");
 517                 return PTR_ERR(dma_q->kthread);
 518         }
 519         /* Wakes thread */
 520         wake_up_interruptible(&dma_q->wq);
 521
 522         dprintk(dev, 1, "returning from %s\n", __FUNCTION__);
 523         return 0;
 524 }
 525
 526 static void vivi_stop_thread(struct vivi_dmaqueue  *dma_q)
 527 {
 528         struct vivi_dev *dev = container_of(dma_q, struct vivi_dev, vidq);
 529
 530         dprintk(dev, 1, "%s\n", __FUNCTION__);
 531         /* shutdown control thread */
 532         if (dma_q->kthread) {
 533                 kthread_stop(dma_q->kthread);
 534                 dma_q->kthread = NULL;
 535         }
 536 }
 537
 538 static int restart_video_queue(struct vivi_dmaqueue *dma_q)
 539 {
 540         struct vivi_dev *dev = container_of(dma_q, struct vivi_dev, vidq);
 541         struct vivi_buffer *buf, *prev;
 542
 543         dprintk(dev, 1, "%s dma_q=0x%08lx\n", __FUNCTION__,
 544                 (unsigned long)dma_q);
 545
 546         if (!list_empty(&dma_q->active)) {
 547                 buf = list_entry(dma_q->active.next,
 548                                  struct vivi_buffer, vb.queue);
 549                 dprintk(dev, 2, "restart_queue [%p/%d]: restart dma\n",
 550                         buf, buf->vb.i);
 551
 552                 dprintk(dev, 1, "Restarting video dma\n");
 553                 vivi_stop_thread(dma_q);
 554
 555                 /* cancel all outstanding capture / vbi requests */
 556                 list_for_each_entry_safe(buf, prev, &dma_q->active, vb.queue) {
 557                         list_del(&buf->vb.queue);
 558                         buf->vb.state = VIDEOBUF_ERROR;
 559                         wake_up(&buf->vb.done);
 560                 }
 561                 mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
 562
 563                 return 0;
 564         }
 565
 566         prev = NULL;
 567         for (;;) {
 568                 if (list_empty(&dma_q->queued))
 569                         return 0;
 570                 buf = list_entry(dma_q->queued.next,
 571                                  struct vivi_buffer, vb.queue);
 572                 if (NULL == prev) {
 573                         list_del(&buf->vb.queue);
 574                         list_add_tail(&buf->vb.queue, &dma_q->active);
 575
 576                         dprintk(dev, 1, "Restarting video dma\n");
 577                         vivi_stop_thread(dma_q);
 578                         vivi_start_thread(dma_q);
 579
 580                         buf->vb.state = VIDEOBUF_ACTIVE;
 581                         mod_timer(&dma_q->timeout, jiffies+BUFFER_TIMEOUT);
 582                         dprintk(dev, 2,
 583                                 "[%p/%d] restart_queue - first active\n",
 584                                 buf, buf->vb.i);
 585
 586                 } else if (prev->vb.width  == buf->vb.width  &&
 587                            prev->vb.height == buf->vb.height &&
 588                            prev->fmt       == buf->fmt) {
 589                         list_del(&buf->vb.queue);
 590                         list_add_tail(&buf->vb.queue, &dma_q->active);
 591                         buf->vb.state = VIDEOBUF_ACTIVE;
 592                         dprintk(dev, 2,
 593                                 "[%p/%d] restart_queue - move to active\n",
 594                                 buf, buf->vb.i);
 595                 } else {
 596                         return 0;
 597                 }
 598                 prev = buf;
 599         }
 600 }
 601
 602 static void vivi_vid_timeout(unsigned long data)
 603 {
 604         struct vivi_dev      *dev  = (struct vivi_dev *)data;
 605         struct vivi_dmaqueue *vidq = &dev->vidq;
 606         struct vivi_buffer   *buf;
 607
 608         spin_lock(&dev->slock);
 609
 610         while (!list_empty(&vidq->active)) {
 611                 buf = list_entry(vidq->active.next,
 612                                  struct vivi_buffer, vb.queue);
 613                 list_del(&buf->vb.queue);
 614                 buf->vb.state = VIDEOBUF_ERROR;
 615                 wake_up(&buf->vb.done);
 616                 printk(KERN_INFO "vivi/0: [%p/%d] timeout\n", buf, buf->vb.i);
 617         }
 618         restart_video_queue(vidq);
 619
 620         spin_unlock(&dev->slock);
 621 }
 622
 623 /* ------------------------------------------------------------------
 624         Videobuf operations
 625    ------------------------------------------------------------------*/
 626 static int
 627 buffer_setup(struct videobuf_queue *vq, unsigned int *count, unsigned int *size)
 628 {
 629         struct vivi_fh  *fh = vq->priv_data;
 630         struct vivi_dev *dev  = fh->dev;
 631
 632         *size = fh->width*fh->height*2;
 633
 634         if (0 == *count)
 635                 *count = 32;
 636
 637         while (*size * *count > vid_limit * 1024 * 1024)
 638                 (*count)--;
 639
 640         dprintk(dev, 1, "%s, count=%d, size=%d\n", __FUNCTION__,
 641                 *count, *size);
 642
 643         return 0;
 644 }
 645
 646 static void free_buffer(struct videobuf_queue *vq, struct vivi_buffer *buf)
 647 {
 648         struct vivi_fh  *fh = vq->priv_data;
 649         struct vivi_dev *dev  = fh->dev;
 650
 651         dprintk(dev, 1, "%s\n", __FUNCTION__);
 652
 653         if (in_interrupt())
 654                 BUG();
 655
 656         videobuf_waiton(&buf->vb, 0, 0);
 657         videobuf_vmalloc_free(&buf->vb);
 658         buf->vb.state = VIDEOBUF_NEEDS_INIT;
 659 }
 660
 661 #define norm_maxw() 1024
 662 #define norm_maxh() 768
 663 static int
 664 buffer_prepare(struct videobuf_queue *vq, struct videobuf_buffer *vb,
 665                                                 enum v4l2_field field)
 666 {
 667         struct vivi_fh     *fh  = vq->priv_data;
 668         struct vivi_dev    *dev = fh->dev;
 669         struct vivi_buffer *buf = container_of(vb, struct vivi_buffer, vb);
 670         int rc, init_buffer = 0;
 671
 672         dprintk(dev, 1, "%s, field=%d\n", __FUNCTION__, field);
 673
 674         BUG_ON(NULL == fh->fmt);
 675         if (fh->width  < 48 || fh->width  > norm_maxw() ||
 676             fh->height < 32 || fh->height > norm_maxh())
 677                 return -EINVAL;
 678         buf->vb.size = fh->width*fh->height*2;
 679         if (0 != buf->vb.baddr  &&  buf->vb.bsize < buf->vb.size)
 680                 return -EINVAL;
 681
 682         if (buf->fmt       != fh->fmt    ||
 683             buf->vb.width  != fh->width  ||
 684             buf->vb.height != fh->height ||
 685         buf->vb.field  != field) {
 686                 buf->fmt       = fh->fmt;
 687                 buf->vb.width  = fh->width;
 688                 buf->vb.height = fh->height;
 689                 buf->vb.field  = field;
 690                 init_buffer = 1;
 691         }
 692
 693         if (VIDEOBUF_NEEDS_INIT == buf->vb.state) {
 694                 rc = videobuf_iolock(vq, &buf->vb, NULL);
 695                 if (rc < 0)
 696                         goto fail;
 697         }
 698
 699         buf->vb.state = VIDEOBUF_PREPARED;
 700
 701         return 0;
 702
 703 fail:
 704         free_buffer(vq, buf);
 705         return rc;
 706 }
 707
 708 static void
 709 buffer_queue(struct videobuf_queue *vq, struct videobuf_buffer *vb)
 710 {
 711         struct vivi_buffer    *buf  = container_of(vb, struct vivi_buffer, vb);
 712         struct vivi_fh        *fh   = vq->priv_data;
 713         struct vivi_dev       *dev  = fh->dev;
 714         struct vivi_dmaqueue  *vidq = &dev->vidq;
 715         struct vivi_buffer    *prev;
 716
 717         if (!list_empty(&vidq->queued)) {
 718                 dprintk(dev, 1, "adding vb queue=0x%08lx\n",
 719                         (unsigned long)&buf->vb.queue);
 720                 list_add_tail(&buf->vb.queue, &vidq->queued);
 721                 buf->vb.state = VIDEOBUF_QUEUED;
 722                 dprintk(dev, 2, "[%p/%d] buffer_queue - append to queued\n",
 723                         buf, buf->vb.i);
 724         } else if (list_empty(&vidq->active)) {
 725                 list_add_tail(&buf->vb.queue, &vidq->active);
 726
 727                 buf->vb.state = VIDEOBUF_ACTIVE;
 728                 mod_timer(&vidq->timeout, jiffies+BUFFER_TIMEOUT);
 729                 dprintk(dev, 2, "[%p/%d] buffer_queue - first active\n",
 730                         buf, buf->vb.i);
 731
 732                 vivi_start_thread(vidq);
 733         } else {
 734                 prev = list_entry(vidq->active.prev,
 735                                   struct vivi_buffer, vb.queue);
 736                 if (prev->vb.width  == buf->vb.width  &&
 737                     prev->vb.height == buf->vb.height &&
 738                     prev->fmt       == buf->fmt) {
 739                         list_add_tail(&buf->vb.queue, &vidq->active);
 740                         buf->vb.state = VIDEOBUF_ACTIVE;
 741                         dprintk(dev, 2,
 742                                 "[%p/%d] buffer_queue - append to active\n",
 743                                 buf, buf->vb.i);
 744
 745                 } else {
 746                         list_add_tail(&buf->vb.queue, &vidq->queued);
 747                         buf->vb.state = VIDEOBUF_QUEUED;
 748                         dprintk(dev, 2,
 749                                 "[%p/%d] buffer_queue - first queued\n",
 750                                 buf, buf->vb.i);
 751                 }
 752         }
 753 }
 754
 755 static void buffer_release(struct videobuf_queue *vq,
 756                            struct videobuf_buffer *vb)
 757 {
 758         struct vivi_buffer   *buf  = container_of(vb, struct vivi_buffer, vb);
 759         struct vivi_fh       *fh   = vq->priv_data;
 760         struct vivi_dev      *dev  = (struct vivi_dev *)fh->dev;
 761         struct vivi_dmaqueue *vidq = &dev->vidq;
 762
 763         dprintk(dev, 1, "%s\n", __FUNCTION__);
 764
 765         vivi_stop_thread(vidq);
 766
 767         free_buffer(vq, buf);
 768 }
 769
 770 static struct videobuf_queue_ops vivi_video_qops = {
 771         .buf_setup      = buffer_setup,
 772         .buf_prepare    = buffer_prepare,
 773         .buf_queue      = buffer_queue,
 774         .buf_release    = buffer_release,
 775 };
 776
 777 /* ------------------------------------------------------------------
 778         IOCTL vidioc handling
 779    ------------------------------------------------------------------*/
 780 static int vidioc_querycap(struct file *file, void  *priv,
 781                                         struct v4l2_capability *cap)
 782 {
 783         strcpy(cap->driver, "vivi");
 784         strcpy(cap->card, "vivi");
 785         cap->version = VIVI_VERSION;
 786         cap->capabilities =     V4L2_CAP_VIDEO_CAPTURE |
 787                                 V4L2_CAP_STREAMING     |
 788                                 V4L2_CAP_READWRITE;
 789         return 0;
 790 }
 791
 792 static int vidioc_enum_fmt_cap(struct file *file, void  *priv,
 793                                         struct v4l2_fmtdesc *f)
 794 {
 795         if (f->index > 0)
 796                 return -EINVAL;
 797
 798         strlcpy(f->description, format.name, sizeof(f->description));
 799         f->pixelformat = format.fourcc;
 800         return 0;
 801 }
 802
 803 static int vidioc_g_fmt_cap(struct file *file, void *priv,
 804                                         struct v4l2_format *f)
 805 {
 806         struct vivi_fh *fh = priv;
 807
 808         f->fmt.pix.width        = fh->width;
 809         f->fmt.pix.height       = fh->height;
 810         f->fmt.pix.field        = fh->vb_vidq.field;
 811         f->fmt.pix.pixelformat  = fh->fmt->fourcc;
 812         f->fmt.pix.bytesperline =
 813                 (f->fmt.pix.width * fh->fmt->depth) >> 3;
 814         f->fmt.pix.sizeimage =
 815                 f->fmt.pix.height * f->fmt.pix.bytesperline;
 816
 817         return (0);
 818 }
 819
 820 static int vidioc_try_fmt_cap(struct file *file, void *priv,
 821                         struct v4l2_format *f)
 822 {
 823         struct vivi_fh  *fh  = priv;
 824         struct vivi_dev *dev = fh->dev;
 825         struct vivi_fmt *fmt;
 826         enum v4l2_field field;
 827         unsigned int maxw, maxh;
 828
 829         if (format.fourcc != f->fmt.pix.pixelformat) {
 830                 dprintk(dev, 1, "Fourcc format (0x%08x) invalid. "
 831                         "Driver accepts only 0x%08x\n",
 832                         f->fmt.pix.pixelformat, format.fourcc);
 833                 return -EINVAL;
 834         }
 835         fmt = &format;
 836
 837         field = f->fmt.pix.field;
 838
 839         if (field == V4L2_FIELD_ANY) {
 840                 field = V4L2_FIELD_INTERLACED;
 841         } else if (V4L2_FIELD_INTERLACED != field) {
 842                 dprintk(dev, 1, "Field type invalid.\n");
 843                 return -EINVAL;
 844         }
 845
 846         maxw  = norm_maxw();
 847         maxh  = norm_maxh();
 848
 849         f->fmt.pix.field = field;
 850         if (f->fmt.pix.height < 32)
 851                 f->fmt.pix.height = 32;
 852         if (f->fmt.pix.height > maxh)
 853                 f->fmt.pix.height = maxh;
 854         if (f->fmt.pix.width < 48)
 855                 f->fmt.pix.width = 48;
 856         if (f->fmt.pix.width > maxw)
 857                 f->fmt.pix.width = maxw;
 858         f->fmt.pix.width &= ~0x03;
 859         f->fmt.pix.bytesperline =
 860                 (f->fmt.pix.width * fmt->depth) >> 3;
 861         f->fmt.pix.sizeimage =
 862                 f->fmt.pix.height * f->fmt.pix.bytesperline;
 863
 864         return 0;
 865 }
 866
 867 /*FIXME: This seems to be generic enough to be at videodev2 */
 868 static int vidioc_s_fmt_cap(struct file *file, void *priv,
 869                                         struct v4l2_format *f)
 870 {
 871         struct vivi_fh  *fh = priv;
 872         int ret = vidioc_try_fmt_cap(file, fh, f);
 873         if (ret < 0)
 874                 return (ret);
 875
 876         fh->fmt           = &format;
 877         fh->width         = f->fmt.pix.width;
 878         fh->height        = f->fmt.pix.height;
 879         fh->vb_vidq.field = f->fmt.pix.field;
 880         fh->type          = f->type;
 881
 882         return (0);
 883 }
 884
 885 static int vidioc_reqbufs(struct file *file, void *priv,
 886                           struct v4l2_requestbuffers *p)
 887 {
 888         struct vivi_fh  *fh = priv;
 889
 890         return (videobuf_reqbufs(&fh->vb_vidq, p));
 891 }
 892
 893 static int vidioc_querybuf(struct file *file, void *priv, struct v4l2_buffer *p)
 894 {
 895         struct vivi_fh  *fh = priv;
 896
 897         return (videobuf_querybuf(&fh->vb_vidq, p));
 898 }
 899
 900 static int vidioc_qbuf(struct file *file, void *priv, struct v4l2_buffer *p)
 901 {
 902         struct vivi_fh *fh = priv;
 903
 904         return (videobuf_qbuf(&fh->vb_vidq, p));
 905 }
 906
 907 static int vidioc_dqbuf(struct file *file, void *priv, struct v4l2_buffer *p)
 908 {
 909         struct vivi_fh  *fh = priv;
 910
 911         return (videobuf_dqbuf(&fh->vb_vidq, p,
 912                                 file->f_flags & O_NONBLOCK));
 913 }
 914
 915 #ifdef CONFIG_VIDEO_V4L1_COMPAT
 916 static int vidiocgmbuf(struct file *file, void *priv, struct video_mbuf *mbuf)
 917 {
 918         struct vivi_fh  *fh = priv;
 919
 920         return videobuf_cgmbuf(&fh->vb_vidq, mbuf, 8);
 921 }
 922 #endif
 923
 924 static int vidioc_streamon(struct file *file, void *priv, enum v4l2_buf_type i)
 925 {
 926         struct vivi_fh  *fh = priv;
 927
 928         if (fh->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
 929                 return -EINVAL;
 930         if (i != fh->type)
 931                 return -EINVAL;
 932
 933         return videobuf_streamon(&fh->vb_vidq);
 934 }
 935
 936 static int vidioc_streamoff(struct file *file, void *priv, enum v4l2_buf_type i)
 937 {
 938         struct vivi_fh  *fh = priv;
 939
 940         if (fh->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
 941                 return -EINVAL;
 942         if (i != fh->type)
 943                 return -EINVAL;
 944
 945         return videobuf_streamoff(&fh->vb_vidq);
 946 }
 947
 948 static int vidioc_s_std(struct file *file, void *priv, v4l2_std_id *i)
 949 {
 950         return 0;
 951 }
 952
 953 /* only one input in this sample driver */
 954 static int vidioc_enum_input(struct file *file, void *priv,
 955                                 struct v4l2_input *inp)
 956 {
 957         if (inp->index != 0)
 958                 return -EINVAL;
 959
 960         inp->type = V4L2_INPUT_TYPE_CAMERA;
 961         inp->std = V4L2_STD_525_60;
 962         strcpy(inp->name, "Camera");
 963
 964         return (0);
 965 }
 966
 967 static int vidioc_g_input(struct file *file, void *priv, unsigned int *i)
 968 {
 969         *i = 0;
 970
 971         return (0);
 972 }
 973 static int vidioc_s_input(struct file *file, void *priv, unsigned int i)
 974 {
 975         if (i > 0)
 976                 return -EINVAL;
 977
 978         return (0);
 979 }
 980
 981         /* --- controls ---------------------------------------------- */
 982 static int vidioc_queryctrl(struct file *file, void *priv,
 983                             struct v4l2_queryctrl *qc)
 984 {
 985         int i;
 986
 987         for (i = 0; i < ARRAY_SIZE(vivi_qctrl); i++)
 988                 if (qc->id && qc->id == vivi_qctrl[i].id) {
 989                         memcpy(qc, &(vivi_qctrl[i]),
 990                                 sizeof(*qc));
 991                         return (0);
 992                 }
 993
 994         return -EINVAL;
 995 }
 996
 997 static int vidioc_g_ctrl(struct file *file, void *priv,
 998                          struct v4l2_control *ctrl)
 999 {
1000         int i;
1001
1002         for (i = 0; i < ARRAY_SIZE(vivi_qctrl); i++)
1003                 if (ctrl->id == vivi_qctrl[i].id) {
1004                         ctrl->value = qctl_regs[i];
1005                         return (0);
1006                 }
1007
1008         return -EINVAL;
1009 }
1010 static int vidioc_s_ctrl(struct file *file, void *priv,
1011                                 struct v4l2_control *ctrl)
1012 {
1013         int i;
1014
1015         for (i = 0; i < ARRAY_SIZE(vivi_qctrl); i++)
1016                 if (ctrl->id == vivi_qctrl[i].id) {
1017                         if (ctrl->value < vivi_qctrl[i].minimum
1018                             || ctrl->value > vivi_qctrl[i].maximum) {
1019                                         return (-ERANGE);
1020                                 }
1021                         qctl_regs[i] = ctrl->value;
1022                         return (0);
1023                 }
1024         return -EINVAL;
1025 }
1026
1027 /* ------------------------------------------------------------------
1028         File operations for the device
1029    ------------------------------------------------------------------*/
1030
1031 #define line_buf_size(norm) (norm_maxw(norm)*(format.depth+7)/8)
1032
1033 static int vivi_open(struct inode *inode, struct file *file)
1034 {
1035         int minor = iminor(inode);
1036         struct vivi_dev *dev;
1037         struct vivi_fh *fh;
1038         int i;
1039
1040         printk(KERN_DEBUG "vivi: open called (minor=%d)\n", minor);
1041
1042         list_for_each_entry(dev, &vivi_devlist, vivi_devlist)
1043                 if (dev->vfd->minor == minor)
1044                         goto found;
1045         return -ENODEV;
1046
1047 found:
1048         /* If more than one user, mutex should be added */
1049         dev->users++;
1050
1051         dprintk(dev, 1, "open minor=%d type=%s users=%d\n", minor,
1052                 v4l2_type_names[V4L2_BUF_TYPE_VIDEO_CAPTURE], dev->users);
1053
1054         /* allocate + initialize per filehandle data */
1055         fh = kzalloc(sizeof(*fh), GFP_KERNEL);
1056         if (NULL == fh) {
1057                 dev->users--;
1058                 return -ENOMEM;
1059         }
1060
1061         file->private_data = fh;
1062         fh->dev      = dev;
1063
1064         fh->type     = V4L2_BUF_TYPE_VIDEO_CAPTURE;
1065         fh->fmt      = &format;
1066         fh->width    = 640;
1067         fh->height   = 480;
1068
1069         /* Put all controls at a sane state */
1070         for (i = 0; i < ARRAY_SIZE(vivi_qctrl); i++)
1071                 qctl_regs[i] = vivi_qctrl[i].default_value;
1072
1073         /* Resets frame counters */
1074         dev->h = 0;
1075         dev->m = 0;
1076         dev->s = 0;
1077         dev->ms = 0;
1078         dev->mv_count = 0;
1079         dev->jiffies = jiffies;
1080         sprintf(dev->timestr, "%02d:%02d:%02d:%03d",
1081                         dev->h, dev->m, dev->s, dev->ms);
1082
1083         videobuf_queue_vmalloc_init(&fh->vb_vidq, &vivi_video_qops,
1084                         NULL, &dev->slock, fh->type, V4L2_FIELD_INTERLACED,
1085                         sizeof(struct vivi_buffer), fh);
1086
1087         return 0;
1088 }
1089
1090 static ssize_t
1091 vivi_read(struct file *file, char __user *data, size_t count, loff_t *ppos)
1092 {
1093         struct vivi_fh *fh = file->private_data;
1094
1095         if (fh->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
1096                 return videobuf_read_stream(&fh->vb_vidq, data, count, ppos, 0,
1097                                         file->f_flags & O_NONBLOCK);
1098         }
1099         return 0;
1100 }
1101
1102 static unsigned int
1103 vivi_poll(struct file *file, struct poll_table_struct *wait)
1104 {
1105         struct vivi_fh        *fh = file->private_data;
1106         struct vivi_dev       *dev = fh->dev;
1107         struct videobuf_queue *q = &fh->vb_vidq;
1108
1109         dprintk(dev, 1, "%s\n", __FUNCTION__);
1110
1111         if (V4L2_BUF_TYPE_VIDEO_CAPTURE != fh->type)
1112                 return POLLERR;
1113
1114         return videobuf_poll_stream(file, q, wait);
1115 }
1116
1117 static int vivi_close(struct inode *inode, struct file *file)
1118 {
1119         struct vivi_fh         *fh = file->private_data;
1120         struct vivi_dev *dev       = fh->dev;
1121         struct vivi_dmaqueue *vidq = &dev->vidq;
1122
1123         int minor = iminor(inode);
1124
1125         vivi_stop_thread(vidq);
1126         videobuf_stop(&fh->vb_vidq);
1127         videobuf_mmap_free(&fh->vb_vidq);
1128
1129         kfree(fh);
1130
1131         dev->users--;
1132
1133         dprintk(dev, 1, "close called (minor=%d, users=%d)\n",
1134                 minor, dev->users);
1135
1136         return 0;
1137 }
1138
1139 static int vivi_release(void)
1140 {
1141         struct vivi_dev *dev;
1142         struct list_head *list;
1143
1144         while (!list_empty(&vivi_devlist)) {
1145                 list = vivi_devlist.next;
1146                 list_del(list);
1147                 dev = list_entry(list, struct vivi_dev, vivi_devlist);
1148
1149                 if (-1 != dev->vfd->minor)
1150                         video_unregister_device(dev->vfd);
1151                 else
1152                         video_device_release(dev->vfd);
1153
1154                 kfree(dev);
1155         }
1156
1157         return 0;
1158 }
1159
1160 static int vivi_mmap(struct file *file, struct vm_area_struct *vma)
1161 {
1162         struct vivi_fh  *fh = file->private_data;
1163         struct vivi_dev *dev = fh->dev;
1164         int ret;
1165
1166         dprintk(dev, 1, "mmap called, vma=0x%08lx\n", (unsigned long)vma);
1167
1168         ret = videobuf_mmap_mapper(&fh->vb_vidq, vma);
1169
1170         dprintk(dev, 1, "vma start=0x%08lx, size=%ld, ret=%d\n",
1171                 (unsigned long)vma->vm_start,
1172                 (unsigned long)vma->vm_end-(unsigned long)vma->vm_start,
1173                 ret);
1174
1175         return ret;
1176 }
1177
1178 static const struct file_operations vivi_fops = {
1179         .owner          = THIS_MODULE,
1180         .open           = vivi_open,
1181         .release        = vivi_close,
1182         .read           = vivi_read,
1183         .poll           = vivi_poll,
1184         .ioctl          = video_ioctl2, /* V4L2 ioctl handler */
1185         .mmap           = vivi_mmap,
1186         .llseek         = no_llseek,
1187 };
1188
1189 static struct video_device vivi_template = {
1190         .name           = "vivi",
1191         .type           = VID_TYPE_CAPTURE,
1192         .fops           = &vivi_fops,
1193         .minor          = -1,
1194         .release        = video_device_release,
1195
1196         .vidioc_querycap      = vidioc_querycap,
1197         .vidioc_enum_fmt_cap  = vidioc_enum_fmt_cap,
1198         .vidioc_g_fmt_cap     = vidioc_g_fmt_cap,
1199         .vidioc_try_fmt_cap   = vidioc_try_fmt_cap,
1200         .vidioc_s_fmt_cap     = vidioc_s_fmt_cap,
1201         .vidioc_reqbufs       = vidioc_reqbufs,
1202         .vidioc_querybuf      = vidioc_querybuf,
1203         .vidioc_qbuf          = vidioc_qbuf,
1204         .vidioc_dqbuf         = vidioc_dqbuf,
1205         .vidioc_s_std         = vidioc_s_std,
1206         .vidioc_enum_input    = vidioc_enum_input,
1207         .vidioc_g_input       = vidioc_g_input,
1208         .vidioc_s_input       = vidioc_s_input,
1209         .vidioc_queryctrl     = vidioc_queryctrl,
1210         .vidioc_g_ctrl        = vidioc_g_ctrl,
1211         .vidioc_s_ctrl        = vidioc_s_ctrl,
1212         .vidioc_streamon      = vidioc_streamon,
1213         .vidioc_streamoff     = vidioc_streamoff,
1214 #ifdef CONFIG_VIDEO_V4L1_COMPAT
1215         .vidiocgmbuf          = vidiocgmbuf,
1216 #endif
1217         .tvnorms              = V4L2_STD_525_60,
1218         .current_norm         = V4L2_STD_NTSC_M,
1219 };
1220 /* -----------------------------------------------------------------
1221         Initialization and module stuff
1222    ------------------------------------------------------------------*/
1223
1224 static int __init vivi_init(void)
1225 {
1226         int ret = -ENOMEM, i;
1227         struct vivi_dev *dev;
1228         struct video_device *vfd;
1229
1230         for (i = 0; i < n_devs; i++) {
1231                 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
1232                 if (NULL == dev)
1233                         break;
1234
1235                 list_add_tail(&dev->vivi_devlist, &vivi_devlist);
1236
1237                 /* init video dma queues */
1238                 INIT_LIST_HEAD(&dev->vidq.active);
1239                 INIT_LIST_HEAD(&dev->vidq.queued);
1240                 init_waitqueue_head(&dev->vidq.wq);
1241
1242                 /* initialize locks */
1243                 mutex_init(&dev->lock);
1244                 spin_lock_init(&dev->slock);
1245
1246                 dev->vidq.timeout.function = vivi_vid_timeout;
1247                 dev->vidq.timeout.data     = (unsigned long)dev;
1248                 init_timer(&dev->vidq.timeout);
1249
1250                 vfd = video_device_alloc();
1251                 if (NULL == vfd)
1252                         break;
1253
1254                 *vfd = vivi_template;
1255
1256                 ret = video_register_device(vfd, VFL_TYPE_GRABBER, video_nr);
1257                 if (ret < 0)
1258                         break;
1259
1260                 snprintf(vfd->name, sizeof(vfd->name), "%s (%i)",
1261                          vivi_template.name, vfd->minor);
1262
1263                 if (video_nr >= 0)
1264                         video_nr++;
1265
1266                 dev->vfd = vfd;
1267         }
1268
1269         if (ret < 0) {
1270                 vivi_release();
1271                 printk(KERN_INFO "Error %d while loading vivi driver\n", ret);
1272         } else
1273                 printk(KERN_INFO "Video Technology Magazine Virtual Video "
1274                                  "Capture Board successfully loaded.\n");
1275         return ret;
1276 }
1277
1278 static void __exit vivi_exit(void)
1279 {
1280         vivi_release();
1281 }
1282
1283 module_init(vivi_init);
1284 module_exit(vivi_exit);
1285
1286 MODULE_DESCRIPTION("Video Technology Magazine Virtual Video Capture Board");
1287 MODULE_AUTHOR("Mauro Carvalho Chehab, Ted Walther and John Sokol");
1288 MODULE_LICENSE("Dual BSD/GPL");
1289
1290 module_param(video_nr, int, 0);
1291 MODULE_PARM_DESC(video_nr, "video iminor start number");
1292
1293 module_param(n_devs, int, 0);
1294 MODULE_PARM_DESC(n_devs, "number of video devices to create");
1295
1296 module_param_named(debug, vivi_template.debug, int, 0444);
1297 MODULE_PARM_DESC(debug, "activates debug info");
1298
1299 module_param(vid_limit, int, 0644);
1300 MODULE_PARM_DESC(vid_limit, "capture memory limit in megabytes");