drivers/media/radio/wl128x/fmdrv_v4l2.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  FM Driver for Connectivity chip of Texas Instruments.
   4  *  This file provides interfaces to V4L2 subsystem.
   5  *
   6  *  This module registers with V4L2 subsystem as Radio
   7  *  data system interface (/dev/radio). During the registration,
   8  *  it will expose two set of function pointers.
   9  *
  10  *    1) File operation related API (open, close, read, write, poll...etc).
  11  *    2) Set of V4L2 IOCTL complaint API.
  12  *
  13  *  Copyright (C) 2011 Texas Instruments
  14  *  Author: Raja Mani <raja_mani@ti.com>
  15  *  Author: Manjunatha Halli <manjunatha_halli@ti.com>
  16  */
  17
  18 #include <linux/export.h>
  19
  20 #include "fmdrv.h"
  21 #include "fmdrv_v4l2.h"
  22 #include "fmdrv_common.h"
  23 #include "fmdrv_rx.h"
  24 #include "fmdrv_tx.h"
  25
  26 static struct video_device gradio_dev;
  27 static u8 radio_disconnected;
  28
  29 /* -- V4L2 RADIO (/dev/radioX) device file operation interfaces --- */
  30
  31 /* Read RX RDS data */
  32 static ssize_t fm_v4l2_fops_read(struct file *file, char __user * buf,
  33                                         size_t count, loff_t *ppos)
  34 {
  35         u8 rds_mode;
  36         int ret;
  37         struct fmdev *fmdev;
  38
  39         fmdev = video_drvdata(file);
  40
  41         if (!radio_disconnected) {
  42                 fmerr("FM device is already disconnected\n");
  43                 return -EIO;
  44         }
  45
  46         if (mutex_lock_interruptible(&fmdev->mutex))
  47                 return -ERESTARTSYS;
  48
  49         /* Turn on RDS mode if it is disabled */
  50         ret = fm_rx_get_rds_mode(fmdev, &rds_mode);
  51         if (ret < 0) {
  52                 fmerr("Unable to read current rds mode\n");
  53                 goto read_unlock;
  54         }
  55
  56         if (rds_mode == FM_RDS_DISABLE) {
  57                 ret = fmc_set_rds_mode(fmdev, FM_RDS_ENABLE);
  58                 if (ret < 0) {
  59                         fmerr("Failed to enable rds mode\n");
  60                         goto read_unlock;
  61                 }
  62         }
  63
  64         /* Copy RDS data from internal buffer to user buffer */
  65         ret = fmc_transfer_rds_from_internal_buff(fmdev, file, buf, count);
  66 read_unlock:
  67         mutex_unlock(&fmdev->mutex);
  68         return ret;
  69 }
  70
  71 /* Write TX RDS data */
  72 static ssize_t fm_v4l2_fops_write(struct file *file, const char __user * buf,
  73                 size_t count, loff_t *ppos)
  74 {
  75         struct tx_rds rds;
  76         int ret;
  77         struct fmdev *fmdev;
  78
  79         ret = copy_from_user(&rds, buf, sizeof(rds));
  80         rds.text[sizeof(rds.text) - 1] = '\0';
  81         fmdbg("(%d)type: %d, text %s, af %d\n",
  82                    ret, rds.text_type, rds.text, rds.af_freq);
  83         if (ret)
  84                 return -EFAULT;
  85
  86         fmdev = video_drvdata(file);
  87         if (mutex_lock_interruptible(&fmdev->mutex))
  88                 return -ERESTARTSYS;
  89         fm_tx_set_radio_text(fmdev, rds.text, rds.text_type);
  90         fm_tx_set_af(fmdev, rds.af_freq);
  91         mutex_unlock(&fmdev->mutex);
  92
  93         return sizeof(rds);
  94 }
  95
  96 static __poll_t fm_v4l2_fops_poll(struct file *file, struct poll_table_struct *pts)
  97 {
  98         int ret;
  99         struct fmdev *fmdev;
 100
 101         fmdev = video_drvdata(file);
 102         mutex_lock(&fmdev->mutex);
 103         ret = fmc_is_rds_data_available(fmdev, file, pts);
 104         mutex_unlock(&fmdev->mutex);
 105         if (ret < 0)
 106                 return EPOLLIN | EPOLLRDNORM;
 107
 108         return 0;
 109 }
 110
 111 /*
 112  * Handle open request for "/dev/radioX" device.
 113  * Start with FM RX mode as default.
 114  */
 115 static int fm_v4l2_fops_open(struct file *file)
 116 {
 117         int ret;
 118         struct fmdev *fmdev = NULL;
 119
 120         /* Don't allow multiple open */
 121         if (radio_disconnected) {
 122                 fmerr("FM device is already opened\n");
 123                 return -EBUSY;
 124         }
 125
 126         fmdev = video_drvdata(file);
 127
 128         if (mutex_lock_interruptible(&fmdev->mutex))
 129                 return -ERESTARTSYS;
 130         ret = fmc_prepare(fmdev);
 131         if (ret < 0) {
 132                 fmerr("Unable to prepare FM CORE\n");
 133                 goto open_unlock;
 134         }
 135
 136         fmdbg("Load FM RX firmware..\n");
 137
 138         ret = fmc_set_mode(fmdev, FM_MODE_RX);
 139         if (ret < 0) {
 140                 fmerr("Unable to load FM RX firmware\n");
 141                 goto open_unlock;
 142         }
 143         radio_disconnected = 1;
 144
 145 open_unlock:
 146         mutex_unlock(&fmdev->mutex);
 147         return ret;
 148 }
 149
 150 static int fm_v4l2_fops_release(struct file *file)
 151 {
 152         int ret;
 153         struct fmdev *fmdev;
 154
 155         fmdev = video_drvdata(file);
 156         if (!radio_disconnected) {
 157                 fmdbg("FM device is already closed\n");
 158                 return 0;
 159         }
 160
 161         mutex_lock(&fmdev->mutex);
 162         ret = fmc_set_mode(fmdev, FM_MODE_OFF);
 163         if (ret < 0) {
 164                 fmerr("Unable to turn off the chip\n");
 165                 goto release_unlock;
 166         }
 167
 168         ret = fmc_release(fmdev);
 169         if (ret < 0) {
 170                 fmerr("FM CORE release failed\n");
 171                 goto release_unlock;
 172         }
 173         radio_disconnected = 0;
 174
 175 release_unlock:
 176         mutex_unlock(&fmdev->mutex);
 177         return ret;
 178 }
 179
 180 /* V4L2 RADIO (/dev/radioX) device IOCTL interfaces */
 181 static int fm_v4l2_vidioc_querycap(struct file *file, void *priv,
 182                 struct v4l2_capability *capability)
 183 {
 184         strscpy(capability->driver, FM_DRV_NAME, sizeof(capability->driver));
 185         strscpy(capability->card, FM_DRV_CARD_SHORT_NAME,
 186                 sizeof(capability->card));
 187         sprintf(capability->bus_info, "UART");
 188         return 0;
 189 }
 190
 191 static int fm_g_volatile_ctrl(struct v4l2_ctrl *ctrl)
 192 {
 193         struct fmdev *fmdev = container_of(ctrl->handler,
 194                         struct fmdev, ctrl_handler);
 195
 196         switch (ctrl->id) {
 197         case  V4L2_CID_TUNE_ANTENNA_CAPACITOR:
 198                 ctrl->val = fm_tx_get_tune_cap_val(fmdev);
 199                 break;
 200         default:
 201                 fmwarn("%s: Unknown IOCTL: %d\n", __func__, ctrl->id);
 202                 break;
 203         }
 204
 205         return 0;
 206 }
 207
 208 static int fm_v4l2_s_ctrl(struct v4l2_ctrl *ctrl)
 209 {
 210         struct fmdev *fmdev = container_of(ctrl->handler,
 211                         struct fmdev, ctrl_handler);
 212
 213         switch (ctrl->id) {
 214         case V4L2_CID_AUDIO_VOLUME:     /* set volume */
 215                 return fm_rx_set_volume(fmdev, (u16)ctrl->val);
 216
 217         case V4L2_CID_AUDIO_MUTE:       /* set mute */
 218                 return fmc_set_mute_mode(fmdev, (u8)ctrl->val);
 219
 220         case V4L2_CID_TUNE_POWER_LEVEL:
 221                 /* set TX power level - ext control */
 222                 return fm_tx_set_pwr_lvl(fmdev, (u8)ctrl->val);
 223
 224         case V4L2_CID_TUNE_PREEMPHASIS:
 225                 return fm_tx_set_preemph_filter(fmdev, (u8) ctrl->val);
 226
 227         default:
 228                 return -EINVAL;
 229         }
 230 }
 231
 232 static int fm_v4l2_vidioc_g_audio(struct file *file, void *priv,
 233                 struct v4l2_audio *audio)
 234 {
 235         memset(audio, 0, sizeof(*audio));
 236         strscpy(audio->name, "Radio", sizeof(audio->name));
 237         audio->capability = V4L2_AUDCAP_STEREO;
 238
 239         return 0;
 240 }
 241
 242 static int fm_v4l2_vidioc_s_audio(struct file *file, void *priv,
 243                 const struct v4l2_audio *audio)
 244 {
 245         if (audio->index != 0)
 246                 return -EINVAL;
 247
 248         return 0;
 249 }
 250
 251 /* Get tuner attributes. If current mode is NOT RX, return error */
 252 static int fm_v4l2_vidioc_g_tuner(struct file *file, void *priv,
 253                 struct v4l2_tuner *tuner)
 254 {
 255         struct fmdev *fmdev = video_drvdata(file);
 256         u32 bottom_freq;
 257         u32 top_freq;
 258         u16 stereo_mono_mode;
 259         u16 rssilvl;
 260         int ret;
 261
 262         if (tuner->index != 0)
 263                 return -EINVAL;
 264
 265         if (fmdev->curr_fmmode != FM_MODE_RX)
 266                 return -EPERM;
 267
 268         ret = fm_rx_get_band_freq_range(fmdev, &bottom_freq, &top_freq);
 269         if (ret != 0)
 270                 return ret;
 271
 272         ret = fm_rx_get_stereo_mono(fmdev, &stereo_mono_mode);
 273         if (ret != 0)
 274                 return ret;
 275
 276         ret = fm_rx_get_rssi_level(fmdev, &rssilvl);
 277         if (ret != 0)
 278                 return ret;
 279
 280         strscpy(tuner->name, "FM", sizeof(tuner->name));
 281         tuner->type = V4L2_TUNER_RADIO;
 282         /* Store rangelow and rangehigh freq in unit of 62.5 Hz */
 283         tuner->rangelow = bottom_freq * 16;
 284         tuner->rangehigh = top_freq * 16;
 285         tuner->rxsubchans = V4L2_TUNER_SUB_MONO | V4L2_TUNER_SUB_STEREO |
 286         ((fmdev->rx.rds.flag == FM_RDS_ENABLE) ? V4L2_TUNER_SUB_RDS : 0);
 287         tuner->capability = V4L2_TUNER_CAP_STEREO | V4L2_TUNER_CAP_RDS |
 288                             V4L2_TUNER_CAP_LOW |
 289                             V4L2_TUNER_CAP_HWSEEK_BOUNDED |
 290                             V4L2_TUNER_CAP_HWSEEK_WRAP;
 291         tuner->audmode = (stereo_mono_mode ?
 292                           V4L2_TUNER_MODE_MONO : V4L2_TUNER_MODE_STEREO);
 293
 294         /*
 295          * Actual rssi value lies in between -128 to +127.
 296          * Convert this range from 0 to 255 by adding +128
 297          */
 298         rssilvl += 128;
 299
 300         /*
 301          * Return signal strength value should be within 0 to 65535.
 302          * Find out correct signal radio by multiplying (65535/255) = 257
 303          */
 304         tuner->signal = rssilvl * 257;
 305         tuner->afc = 0;
 306
 307         return ret;
 308 }
 309
 310 /*
 311  * Set tuner attributes. If current mode is NOT RX, set to RX.
 312  * Currently, we set only audio mode (mono/stereo) and RDS state (on/off).
 313  * Should we set other tuner attributes, too?
 314  */
 315 static int fm_v4l2_vidioc_s_tuner(struct file *file, void *priv,
 316                 const struct v4l2_tuner *tuner)
 317 {
 318         struct fmdev *fmdev = video_drvdata(file);
 319         u16 aud_mode;
 320         u8 rds_mode;
 321         int ret;
 322
 323         if (tuner->index != 0)
 324                 return -EINVAL;
 325
 326         aud_mode = (tuner->audmode == V4L2_TUNER_MODE_STEREO) ?
 327                         FM_STEREO_MODE : FM_MONO_MODE;
 328         rds_mode = (tuner->rxsubchans & V4L2_TUNER_SUB_RDS) ?
 329                         FM_RDS_ENABLE : FM_RDS_DISABLE;
 330
 331         if (fmdev->curr_fmmode != FM_MODE_RX) {
 332                 ret = fmc_set_mode(fmdev, FM_MODE_RX);
 333                 if (ret < 0) {
 334                         fmerr("Failed to set RX mode\n");
 335                         return ret;
 336                 }
 337         }
 338
 339         ret = fmc_set_stereo_mono(fmdev, aud_mode);
 340         if (ret < 0) {
 341                 fmerr("Failed to set RX stereo/mono mode\n");
 342                 return ret;
 343         }
 344
 345         ret = fmc_set_rds_mode(fmdev, rds_mode);
 346         if (ret < 0)
 347                 fmerr("Failed to set RX RDS mode\n");
 348
 349         return ret;
 350 }
 351
 352 /* Get tuner or modulator radio frequency */
 353 static int fm_v4l2_vidioc_g_freq(struct file *file, void *priv,
 354                 struct v4l2_frequency *freq)
 355 {
 356         struct fmdev *fmdev = video_drvdata(file);
 357         int ret;
 358
 359         ret = fmc_get_freq(fmdev, &freq->frequency);
 360         if (ret < 0) {
 361                 fmerr("Failed to get frequency\n");
 362                 return ret;
 363         }
 364
 365         /* Frequency unit of 62.5 Hz*/
 366         freq->frequency = (u32) freq->frequency * 16;
 367
 368         return 0;
 369 }
 370
 371 /* Set tuner or modulator radio frequency */
 372 static int fm_v4l2_vidioc_s_freq(struct file *file, void *priv,
 373                 const struct v4l2_frequency *freq)
 374 {
 375         struct fmdev *fmdev = video_drvdata(file);
 376
 377         /*
 378          * As V4L2_TUNER_CAP_LOW is set 1 user sends the frequency
 379          * in units of 62.5 Hz.
 380          */
 381         return fmc_set_freq(fmdev, freq->frequency / 16);
 382 }
 383
 384 /* Set hardware frequency seek. If current mode is NOT RX, set it RX. */
 385 static int fm_v4l2_vidioc_s_hw_freq_seek(struct file *file, void *priv,
 386                 const struct v4l2_hw_freq_seek *seek)
 387 {
 388         struct fmdev *fmdev = video_drvdata(file);
 389         int ret;
 390
 391         if (file->f_flags & O_NONBLOCK)
 392                 return -EWOULDBLOCK;
 393
 394         if (fmdev->curr_fmmode != FM_MODE_RX) {
 395                 ret = fmc_set_mode(fmdev, FM_MODE_RX);
 396                 if (ret != 0) {
 397                         fmerr("Failed to set RX mode\n");
 398                         return ret;
 399                 }
 400         }
 401
 402         ret = fm_rx_seek(fmdev, seek->seek_upward, seek->wrap_around,
 403                         seek->spacing);
 404         if (ret < 0)
 405                 fmerr("RX seek failed - %d\n", ret);
 406
 407         return ret;
 408 }
 409 /* Get modulator attributes. If mode is not TX, return no attributes. */
 410 static int fm_v4l2_vidioc_g_modulator(struct file *file, void *priv,
 411                 struct v4l2_modulator *mod)
 412 {
 413         struct fmdev *fmdev = video_drvdata(file);
 414
 415         if (mod->index != 0)
 416                 return -EINVAL;
 417
 418         if (fmdev->curr_fmmode != FM_MODE_TX)
 419                 return -EPERM;
 420
 421         mod->txsubchans = ((fmdev->tx_data.aud_mode == FM_STEREO_MODE) ?
 422                                 V4L2_TUNER_SUB_STEREO : V4L2_TUNER_SUB_MONO) |
 423                                 ((fmdev->tx_data.rds.flag == FM_RDS_ENABLE) ?
 424                                 V4L2_TUNER_SUB_RDS : 0);
 425
 426         mod->capability = V4L2_TUNER_CAP_STEREO | V4L2_TUNER_CAP_RDS |
 427                                 V4L2_TUNER_CAP_LOW;
 428
 429         return 0;
 430 }
 431
 432 /* Set modulator attributes. If mode is not TX, set to TX. */
 433 static int fm_v4l2_vidioc_s_modulator(struct file *file, void *priv,
 434                 const struct v4l2_modulator *mod)
 435 {
 436         struct fmdev *fmdev = video_drvdata(file);
 437         u8 rds_mode;
 438         u16 aud_mode;
 439         int ret;
 440
 441         if (mod->index != 0)
 442                 return -EINVAL;
 443
 444         if (fmdev->curr_fmmode != FM_MODE_TX) {
 445                 ret = fmc_set_mode(fmdev, FM_MODE_TX);
 446                 if (ret != 0) {
 447                         fmerr("Failed to set TX mode\n");
 448                         return ret;
 449                 }
 450         }
 451
 452         aud_mode = (mod->txsubchans & V4L2_TUNER_SUB_STEREO) ?
 453                         FM_STEREO_MODE : FM_MONO_MODE;
 454         rds_mode = (mod->txsubchans & V4L2_TUNER_SUB_RDS) ?
 455                         FM_RDS_ENABLE : FM_RDS_DISABLE;
 456         ret = fm_tx_set_stereo_mono(fmdev, aud_mode);
 457         if (ret < 0) {
 458                 fmerr("Failed to set mono/stereo mode for TX\n");
 459                 return ret;
 460         }
 461         ret = fm_tx_set_rds_mode(fmdev, rds_mode);
 462         if (ret < 0)
 463                 fmerr("Failed to set rds mode for TX\n");
 464
 465         return ret;
 466 }
 467
 468 static const struct v4l2_file_operations fm_drv_fops = {
 469         .owner = THIS_MODULE,
 470         .read = fm_v4l2_fops_read,
 471         .write = fm_v4l2_fops_write,
 472         .poll = fm_v4l2_fops_poll,
 473         .unlocked_ioctl = video_ioctl2,
 474         .open = fm_v4l2_fops_open,
 475         .release = fm_v4l2_fops_release,
 476 };
 477
 478 static const struct v4l2_ctrl_ops fm_ctrl_ops = {
 479         .s_ctrl = fm_v4l2_s_ctrl,
 480         .g_volatile_ctrl = fm_g_volatile_ctrl,
 481 };
 482 static const struct v4l2_ioctl_ops fm_drv_ioctl_ops = {
 483         .vidioc_querycap = fm_v4l2_vidioc_querycap,
 484         .vidioc_g_audio = fm_v4l2_vidioc_g_audio,
 485         .vidioc_s_audio = fm_v4l2_vidioc_s_audio,
 486         .vidioc_g_tuner = fm_v4l2_vidioc_g_tuner,
 487         .vidioc_s_tuner = fm_v4l2_vidioc_s_tuner,
 488         .vidioc_g_frequency = fm_v4l2_vidioc_g_freq,
 489         .vidioc_s_frequency = fm_v4l2_vidioc_s_freq,
 490         .vidioc_s_hw_freq_seek = fm_v4l2_vidioc_s_hw_freq_seek,
 491         .vidioc_g_modulator = fm_v4l2_vidioc_g_modulator,
 492         .vidioc_s_modulator = fm_v4l2_vidioc_s_modulator
 493 };
 494
 495 /* V4L2 RADIO device parent structure */
 496 static const struct video_device fm_viddev_template = {
 497         .fops = &fm_drv_fops,
 498         .ioctl_ops = &fm_drv_ioctl_ops,
 499         .name = FM_DRV_NAME,
 500         .release = video_device_release_empty,
 501         /*
 502          * To ensure both the tuner and modulator ioctls are accessible we
 503          * set the vfl_dir to M2M to indicate this.
 504          *
 505          * It is not really a mem2mem device of course, but it can both receive
 506          * and transmit using the same radio device. It's the only radio driver
 507          * that does this and it should really be split in two radio devices,
 508          * but that would affect applications using this driver.
 509          */
 510         .vfl_dir = VFL_DIR_M2M,
 511         .device_caps = V4L2_CAP_HW_FREQ_SEEK | V4L2_CAP_TUNER | V4L2_CAP_RADIO |
 512                        V4L2_CAP_MODULATOR | V4L2_CAP_AUDIO |
 513                        V4L2_CAP_READWRITE | V4L2_CAP_RDS_CAPTURE,
 514 };
 515
 516 int fm_v4l2_init_video_device(struct fmdev *fmdev, int radio_nr)
 517 {
 518         struct v4l2_ctrl *ctrl;
 519         int ret;
 520
 521         strscpy(fmdev->v4l2_dev.name, FM_DRV_NAME,
 522                 sizeof(fmdev->v4l2_dev.name));
 523         ret = v4l2_device_register(NULL, &fmdev->v4l2_dev);
 524         if (ret < 0)
 525                 return ret;
 526
 527         /* Init mutex for core locking */
 528         mutex_init(&fmdev->mutex);
 529
 530         /* Setup FM driver's V4L2 properties */
 531         gradio_dev = fm_viddev_template;
 532
 533         video_set_drvdata(&gradio_dev, fmdev);
 534
 535         gradio_dev.lock = &fmdev->mutex;
 536         gradio_dev.v4l2_dev = &fmdev->v4l2_dev;
 537
 538         /* Register with V4L2 subsystem as RADIO device */
 539         if (video_register_device(&gradio_dev, VFL_TYPE_RADIO, radio_nr)) {
 540                 v4l2_device_unregister(&fmdev->v4l2_dev);
 541                 fmerr("Could not register video device\n");
 542                 return -ENOMEM;
 543         }
 544
 545         fmdev->radio_dev = &gradio_dev;
 546
 547         /* Register to v4l2 ctrl handler framework */
 548         fmdev->radio_dev->ctrl_handler = &fmdev->ctrl_handler;
 549
 550         ret = v4l2_ctrl_handler_init(&fmdev->ctrl_handler, 5);
 551         if (ret < 0) {
 552                 fmerr("(fmdev): Can't init ctrl handler\n");
 553                 v4l2_ctrl_handler_free(&fmdev->ctrl_handler);
 554                 video_unregister_device(fmdev->radio_dev);
 555                 v4l2_device_unregister(&fmdev->v4l2_dev);
 556                 return -EBUSY;
 557         }
 558
 559         /*
 560          * Following controls are handled by V4L2 control framework.
 561          * Added in ascending ID order.
 562          */
 563         v4l2_ctrl_new_std(&fmdev->ctrl_handler, &fm_ctrl_ops,
 564                         V4L2_CID_AUDIO_VOLUME, FM_RX_VOLUME_MIN,
 565                         FM_RX_VOLUME_MAX, 1, FM_RX_VOLUME_MAX);
 566
 567         v4l2_ctrl_new_std(&fmdev->ctrl_handler, &fm_ctrl_ops,
 568                         V4L2_CID_AUDIO_MUTE, 0, 1, 1, 1);
 569
 570         v4l2_ctrl_new_std_menu(&fmdev->ctrl_handler, &fm_ctrl_ops,
 571                         V4L2_CID_TUNE_PREEMPHASIS, V4L2_PREEMPHASIS_75_uS,
 572                         0, V4L2_PREEMPHASIS_75_uS);
 573
 574         v4l2_ctrl_new_std(&fmdev->ctrl_handler, &fm_ctrl_ops,
 575                         V4L2_CID_TUNE_POWER_LEVEL, FM_PWR_LVL_LOW,
 576                         FM_PWR_LVL_HIGH, 1, FM_PWR_LVL_HIGH);
 577
 578         ctrl = v4l2_ctrl_new_std(&fmdev->ctrl_handler, &fm_ctrl_ops,
 579                         V4L2_CID_TUNE_ANTENNA_CAPACITOR, 0,
 580                         255, 1, 255);
 581
 582         if (ctrl)
 583                 ctrl->flags |= V4L2_CTRL_FLAG_VOLATILE;
 584
 585         return 0;
 586 }
 587
 588 void *fm_v4l2_deinit_video_device(void)
 589 {
 590         struct fmdev *fmdev;
 591
 592
 593         fmdev = video_get_drvdata(&gradio_dev);
 594
 595         /* Unregister to v4l2 ctrl handler framework*/
 596         v4l2_ctrl_handler_free(&fmdev->ctrl_handler);
 597
 598         /* Unregister RADIO device from V4L2 subsystem */
 599         video_unregister_device(&gradio_dev);
 600
 601         v4l2_device_unregister(&fmdev->v4l2_dev);
 602
 603         return fmdev;
 604 }