aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/media/radio/radio-mr800.c
blob: a860a72a58ecc39c7a37d2a5f36e87c2bedad161 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
/*
 * A driver for the AverMedia MR 800 USB FM radio. This device plugs
 * into both the USB and an analog audio input, so this thing
 * only deals with initialization and frequency setting, the
 * audio data has to be handled by a sound driver.
 *
 * Copyright (c) 2008 Alexey Klimov <klimov.linux@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/*
 * Big thanks to authors and contributors of dsbr100.c and radio-si470x.c
 *
 * When work was looked pretty good, i discover this:
 * http://av-usbradio.sourceforge.net/index.php
 * http://sourceforge.net/projects/av-usbradio/
 * Latest release of theirs project was in 2005.
 * Probably, this driver could be improved through using their
 * achievements (specifications given).
 * Also, Faidon Liambotis <paravoid@debian.org> wrote nice driver for this radio
 * in 2007. He allowed to use his driver to improve current mr800 radio driver.
 * http://kerneltrap.org/mailarchive/linux-usb-devel/2007/10/11/342492
 *
 * Version 0.01:	First working version.
 * 			It's required to blacklist AverMedia USB Radio
 * 			in usbhid/hid-quirks.c
 * Version 0.10:	A lot of cleanups and fixes: unpluging the device,
 * 			few mutex locks were added, codinstyle issues, etc.
 * 			Added stereo support. Thanks to
 * 			Douglas Schilling Landgraf <dougsland@gmail.com> and
 * 			David Ellingsworth <david@identd.dyndns.org>
 * 			for discussion, help and support.
 * Version 0.11:	Converted to v4l2_device.
 *
 * Many things to do:
 * 	- Correct power management of device (suspend & resume)
 * 	- Add code for scanning and smooth tuning
 * 	- Add code for sensitivity value
 * 	- Correct mistakes
 * 	- In Japan another FREQ_MIN and FREQ_MAX
 */

/* kernel includes */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <linux/usb.h>
#include <linux/mutex.h>

/* driver and module definitions */
#define DRIVER_AUTHOR "Alexey Klimov <klimov.linux@gmail.com>"
#define DRIVER_DESC "AverMedia MR 800 USB FM radio driver"
#define DRIVER_VERSION "0.1.2"

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");
MODULE_VERSION(DRIVER_VERSION);

#define USB_AMRADIO_VENDOR 0x07ca
#define USB_AMRADIO_PRODUCT 0xb800

/* dev_warn macro with driver name */
#define MR800_DRIVER_NAME "radio-mr800"
#define amradio_dev_warn(dev, fmt, arg...)				\
		dev_warn(dev, MR800_DRIVER_NAME " - " fmt, ##arg)

#define amradio_dev_err(dev, fmt, arg...) \
		dev_err(dev, MR800_DRIVER_NAME " - " fmt, ##arg)

/* Probably USB_TIMEOUT should be modified in module parameter */
#define BUFFER_LENGTH 8
#define USB_TIMEOUT 500

/* Frequency limits in MHz -- these are European values.  For Japanese
devices, that would be 76 and 91.  */
#define FREQ_MIN  87.5
#define FREQ_MAX 108.0
#define FREQ_MUL 16000

/*
 * Commands that device should understand
 * List isn't full and will be updated with implementation of new functions
 */
#define AMRADIO_SET_FREQ	0xa4
#define AMRADIO_SET_MUTE	0xab
#define AMRADIO_SET_MONO	0xae

/* Comfortable defines for amradio_set_mute */
#define AMRADIO_START		0x00
#define AMRADIO_STOP		0x01

/* Comfortable defines for amradio_set_stereo */
#define WANT_STEREO		0x00
#define WANT_MONO		0x01

/* module parameter */
static int radio_nr = -1;
module_param(radio_nr, int, 0);
MODULE_PARM_DESC(radio_nr, "Radio Nr");

static int usb_amradio_probe(struct usb_interface *intf,
			     const struct usb_device_id *id);
static void usb_amradio_disconnect(struct usb_interface *intf);
static int usb_amradio_open(struct file *file);
static int usb_amradio_close(struct file *file);
static int usb_amradio_suspend(struct usb_interface *intf,
				pm_message_t message);
static int usb_amradio_resume(struct usb_interface *intf);

/* Data for one (physical) device */
struct amradio_device {
	/* reference to USB and video device */
	struct usb_device *usbdev;
	struct usb_interface *intf;
	struct video_device videodev;
	struct v4l2_device v4l2_dev;

	unsigned char *buffer;
	struct mutex lock;	/* buffer locking */
	int curfreq;
	int stereo;
	int muted;
	int initialized;
};

static inline struct amradio_device *to_amradio_dev(struct v4l2_device *v4l2_dev)
{
	return container_of(v4l2_dev, struct amradio_device, v4l2_dev);
}

/* USB Device ID List */
static struct usb_device_id usb_amradio_device_table[] = {
	{USB_DEVICE_AND_INTERFACE_INFO(USB_AMRADIO_VENDOR, USB_AMRADIO_PRODUCT,
							USB_CLASS_HID, 0, 0) },
	{ }						/* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, usb_amradio_device_table);

/* USB subsystem interface */
static struct usb_driver usb_amradio_driver = {
	.name			= MR800_DRIVER_NAME,
	.probe			= usb_amradio_probe,
	.disconnect		= usb_amradio_disconnect,
	.suspend		= usb_amradio_suspend,
	.resume			= usb_amradio_resume,
	.reset_resume		= usb_amradio_resume,
	.id_table		= usb_amradio_device_table,
	.supports_autosuspend	= 1,
};

/* switch on/off the radio. Send 8 bytes to device */
static int amradio_set_mute(struct amradio_device *radio, char argument)
{
	int retval;
	int size;

	radio->buffer[0] = 0x00;
	radio->buffer[1] = 0x55;
	radio->buffer[2] = 0xaa;
	radio->buffer[3] = 0x00;
	radio->buffer[4] = AMRADIO_SET_MUTE;
	radio->buffer[5] = argument;
	radio->buffer[6] = 0x00;
	radio->buffer[7] = 0x00;

	retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
		(void *) (radio->buffer), BUFFER_LENGTH, &size, USB_TIMEOUT);

	if (retval < 0 || size != BUFFER_LENGTH) {
		amradio_dev_warn(&radio->videodev.dev, "set mute failed\n");
		return retval;
	}

	radio->muted = argument;

	return retval;
}

/* set a frequency, freq is defined by v4l's TUNER_LOW, i.e. 1/16th kHz */
static int amradio_setfreq(struct amradio_device *radio, int freq)
{
	int retval;
	int size;
	unsigned short freq_send = 0x10 + (freq >> 3) / 25;

	radio->buffer[0] = 0x00;
	radio->buffer[1] = 0x55;
	radio->buffer[2] = 0xaa;
	radio->buffer[3] = 0x03;
	radio->buffer[4] = AMRADIO_SET_FREQ;
	radio->buffer[5] = 0x00;
	radio->buffer[6] = 0x00;
	radio->buffer[7] = 0x08;

	retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
		(void *) (radio->buffer), BUFFER_LENGTH, &size, USB_TIMEOUT);

	if (retval < 0 || size != BUFFER_LENGTH)
		goto out_err;

	/* frequency is calculated from freq_send and placed in first 2 bytes */
	radio->buffer[0] = (freq_send >> 8) & 0xff;
	radio->buffer[1] = freq_send & 0xff;
	radio->buffer[2] = 0x01;
	radio->buffer[3] = 0x00;
	radio->buffer[4] = 0x00;
	/* 5 and 6 bytes of buffer already = 0x00 */
	radio->buffer[7] = 0x00;

	retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
		(void *) (radio->buffer), BUFFER_LENGTH, &size, USB_TIMEOUT);

	if (retval < 0 || size != BUFFER_LENGTH)
		goto out_err;

	radio->curfreq = freq;
	goto out;

out_err:
	amradio_dev_warn(&radio->videodev.dev, "set frequency failed\n");
out:
	return retval;
}

static int amradio_set_stereo(struct amradio_device *radio, char argument)
{
	int retval;
	int size;

	radio->buffer[0] = 0x00;
	radio->buffer[1] = 0x55;
	radio->buffer[2] = 0xaa;
	radio->buffer[3] = 0x00;
	radio->buffer[4] = AMRADIO_SET_MONO;
	radio->buffer[5] = argument;
	radio->buffer[6] = 0x00;
	radio->buffer[7] = 0x00;

	retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
		(void *) (radio->buffer), BUFFER_LENGTH, &size, USB_TIMEOUT);

	if (retval < 0 || size != BUFFER_LENGTH) {
		amradio_dev_warn(&radio->videodev.dev, "set stereo failed\n");
		return retval;
	}

	if (argument == WANT_STEREO)
		radio->stereo = 1;
	else
		radio->stereo = 0;

	return retval;
}

/* Handle unplugging the device.
 * We call video_unregister_device in any case.
 * The last function called in this procedure is
 * usb_amradio_device_release.
 */
static void usb_amradio_disconnect(struct usb_interface *intf)
{
	struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));

	mutex_lock(&radio->lock);
	/* increase the device node's refcount */
	get_device(&radio->videodev.dev);
	v4l2_device_disconnect(&radio->v4l2_dev);
	video_unregister_device(&radio->videodev);
	mutex_unlock(&radio->lock);
	/* decrease the device node's refcount, allowing it to be released */
	put_device(&radio->videodev.dev);
}

/* vidioc_querycap - query device capabilities */
static int vidioc_querycap(struct file *file, void *priv,
					struct v4l2_capability *v)
{
	struct amradio_device *radio = file->private_data;

	strlcpy(v->driver, "radio-mr800", sizeof(v->driver));
	strlcpy(v->card, "AverMedia MR 800 USB FM Radio", sizeof(v->card));
	usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
	v->capabilities = V4L2_CAP_TUNER;
	return 0;
}

/* vidioc_g_tuner - get tuner attributes */
static int vidioc_g_tuner(struct file *file, void *priv,
				struct v4l2_tuner *v)
{
	struct amradio_device *radio = file->private_data;
	int retval;

	if (v->index > 0)
		return -EINVAL;

/* TODO: Add function which look is signal stereo or not
 * 	amradio_getstat(radio);
 */

/* we call amradio_set_stereo to set radio->stereo
 * Honestly, amradio_getstat should cover this in future and
 * amradio_set_stereo shouldn't be here
 */
	retval = amradio_set_stereo(radio, WANT_STEREO);

	strcpy(v->name, "FM");
	v->type = V4L2_TUNER_RADIO;
	v->rangelow = FREQ_MIN * FREQ_MUL;
	v->rangehigh = FREQ_MAX * FREQ_MUL;
	v->rxsubchans = V4L2_TUNER_SUB_MONO | V4L2_TUNER_SUB_STEREO;
	v->capability = V4L2_TUNER_CAP_LOW;
	if (radio->stereo)
		v->audmode = V4L2_TUNER_MODE_STEREO;
	else
		v->audmode = V4L2_TUNER_MODE_MONO;
	v->signal = 0xffff;     /* Can't get the signal strength, sad.. */
	v->afc = 0; /* Don't know what is this */

	return retval;
}

/* vidioc_s_tuner - set tuner attributes */
static int vidioc_s_tuner(struct file *file, void *priv,
				struct v4l2_tuner *v)
{
	struct amradio_device *radio = file->private_data;
	int retval = -EINVAL;

	if (v->index > 0)
		return -EINVAL;

	/* mono/stereo selector */
	switch (v->audmode) {
	case V4L2_TUNER_MODE_MONO:
		retval = amradio_set_stereo(radio, WANT_MONO);
		break;
	case V4L2_TUNER_MODE_STEREO:
		retval = amradio_set_stereo(radio, WANT_STEREO);
		break;
	}

	return retval;
}

/* vidioc_s_frequency - set tuner radio frequency */
static int vidioc_s_frequency(struct file *file, void *priv,
				struct v4l2_frequency *f)
{
	struct amradio_device *radio = file->private_data;

	if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
		return -EINVAL;
	return amradio_setfreq(radio, f->frequency);
}

/* vidioc_g_frequency - get tuner radio frequency */
static int vidioc_g_frequency(struct file *file, void *priv,
				struct v4l2_frequency *f)
{
	struct amradio_device *radio = file->private_data;

	if (f->tuner != 0)
		return -EINVAL;
	f->type = V4L2_TUNER_RADIO;
	f->frequency = radio->curfreq;

	return 0;
}

/* vidioc_queryctrl - enumerate control items */
static int vidioc_queryctrl(struct file *file, void *priv,
				struct v4l2_queryctrl *qc)
{
	switch (qc->id) {
	case V4L2_CID_AUDIO_MUTE:
		return v4l2_ctrl_query_fill(qc, 0, 1, 1, 1);
	}

	return -EINVAL;
}

/* vidioc_g_ctrl - get the value of a control */
static int vidioc_g_ctrl(struct file *file, void *priv,
				struct v4l2_control *ctrl)
{
	struct amradio_device *radio = file->private_data;

	switch (ctrl->id) {
	case V4L2_CID_AUDIO_MUTE:
		ctrl->value = radio->muted;
		return 0;
	}

	return -EINVAL;
}

/* vidioc_s_ctrl - set the value of a control */
static int vidioc_s_ctrl(struct file *file, void *priv,
				struct v4l2_control *ctrl)
{
	struct amradio_device *radio = file->private_data;
	int retval = -EINVAL;

	switch (ctrl->id) {
	case V4L2_CID_AUDIO_MUTE:
		if (ctrl->value)
			retval = amradio_set_mute(radio, AMRADIO_STOP);
		else
			retval = amradio_set_mute(radio, AMRADIO_START);

		break;
	}

	return retval;
}

/* vidioc_g_audio - get audio attributes */
static int vidioc_g_audio(struct file *file, void *priv,
				struct v4l2_audio *a)
{
	if (a->index > 1)
		return -EINVAL;

	strcpy(a->name, "Radio");
	a->capability = V4L2_AUDCAP_STEREO;
	return 0;
}

/* vidioc_s_audio - set audio attributes  */
static int vidioc_s_audio(struct file *file, void *priv,
					struct v4l2_audio *a)
{
	if (a->index != 0)
		return -EINVAL;
	return 0;
}

/* vidioc_g_input - get input */
static int vidioc_g_input(struct file *filp, void *priv, unsigned int *i)
{
	*i = 0;
	return 0;
}

/* vidioc_s_input - set input */
static int vidioc_s_input(struct file *filp, void *priv, unsigned int i)
{
	if (i != 0)
		return -EINVAL;
	return 0;
}

static int usb_amradio_init(struct amradio_device *radio)
{
	int retval;

	retval = amradio_set_mute(radio, AMRADIO_STOP);
	if (retval)
		goto out_err;

	retval = amradio_set_stereo(radio, WANT_STEREO);
	if (retval)
		goto out_err;

	radio->initialized = 1;
	goto out;

out_err:
	amradio_dev_err(&radio->videodev.dev, "initialization failed\n");
out:
	return retval;
}

/* open device - amradio_start() and amradio_setfreq() */
static int usb_amradio_open(struct file *file)
{
	struct amradio_device *radio = video_drvdata(file);
	int retval;

	file->private_data = radio;
	retval = usb_autopm_get_interface(radio->intf);
	if (retval)
		return retval;

	if (unlikely(!radio->initialized)) {
		retval = usb_amradio_init(radio);
		if (retval)
			usb_autopm_put_interface(radio->intf);
	}
	return retval;
}

/*close device */
static int usb_amradio_close(struct file *file)
{
	struct amradio_device *radio = file->private_data;

	if (video_is_registered(&radio->videodev))
		usb_autopm_put_interface(radio->intf);
	return 0;
}

/* Suspend device - stop device. Need to be checked and fixed */
static int usb_amradio_suspend(struct usb_interface *intf, pm_message_t message)
{
	struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));

	mutex_lock(&radio->lock);
	if (!radio->muted && radio->initialized) {
		amradio_set_mute(radio, AMRADIO_STOP);
		radio->muted = 0;
	}
	mutex_unlock(&radio->lock);

	dev_info(&intf->dev, "going into suspend..\n");
	return 0;
}

/* Resume device - start device. Need to be checked and fixed */
static int usb_amradio_resume(struct usb_interface *intf)
{
	struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));

	mutex_lock(&radio->lock);
	if (unlikely(!radio->initialized))
		goto unlock;

	if (radio->stereo)
		amradio_set_stereo(radio, WANT_STEREO);
	else
		amradio_set_stereo(radio, WANT_MONO);

	amradio_setfreq(radio, radio->curfreq);

	if (!radio->muted)
		amradio_set_mute(radio, AMRADIO_START);

unlock:
	mutex_unlock(&radio->lock);

	dev_info(&intf->dev, "coming out of suspend..\n");
	return 0;
}

/* File system interface */
static const struct v4l2_file_operations usb_amradio_fops = {
	.owner		= THIS_MODULE,
	.open		= usb_amradio_open,
	.release	= usb_amradio_close,
	.unlocked_ioctl	= video_ioctl2,
};

static const struct v4l2_ioctl_ops usb_amradio_ioctl_ops = {
	.vidioc_querycap    = vidioc_querycap,
	.vidioc_g_tuner     = vidioc_g_tuner,
	.vidioc_s_tuner     = vidioc_s_tuner,
	.vidioc_g_frequency = vidioc_g_frequency,
	.vidioc_s_frequency = vidioc_s_frequency,
	.vidioc_queryctrl   = vidioc_queryctrl,
	.vidioc_g_ctrl      = vidioc_g_ctrl,
	.vidioc_s_ctrl      = vidioc_s_ctrl,
	.vidioc_g_audio     = vidioc_g_audio,
	.vidioc_s_audio     = vidioc_s_audio,
	.vidioc_g_input     = vidioc_g_input,
	.vidioc_s_input     = vidioc_s_input,
};

static void usb_amradio_video_device_release(struct video_device *videodev)
{
	struct amradio_device *radio = video_get_drvdata(videodev);

	/* free rest memory */
	kfree(radio->buffer);
	kfree(radio);
}

/* check if the device is present and register with v4l and usb if it is */
static int usb_amradio_probe(struct usb_interface *intf,
				const struct usb_device_id *id)
{
	struct amradio_device *radio;
	int retval = 0;

	radio = kzalloc(sizeof(struct amradio_device), GFP_KERNEL);

	if (!radio) {
		dev_err(&intf->dev, "kmalloc for amradio_device failed\n");
		retval = -ENOMEM;
		goto err;
	}

	radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);

	if (!radio->buffer) {
		dev_err(&intf->dev, "kmalloc for radio->buffer failed\n");
		retval = -ENOMEM;
		goto err_nobuf;
	}

	retval = v4l2_device_register(&intf->dev, &radio->v4l2_dev);
	if (retval < 0) {
		dev_err(&intf->dev, "couldn't register v4l2_device\n");
		goto err_v4l2;
	}

	mutex_init(&radio->lock);

	strlcpy(radio->videodev.name, radio->v4l2_dev.name,
		sizeof(radio->videodev.name));
	radio->videodev.v4l2_dev = &radio->v4l2_dev;
	radio->videodev.fops = &usb_amradio_fops;
	radio->videodev.ioctl_ops = &usb_amradio_ioctl_ops;
	radio->videodev.release = usb_amradio_video_device_release;
	radio->videodev.lock = &radio->lock;

	radio->usbdev = interface_to_usbdev(intf);
	radio->intf = intf;
	radio->curfreq = 95.16 * FREQ_MUL;

	video_set_drvdata(&radio->videodev, radio);

	retval = video_register_device(&radio->videodev, VFL_TYPE_RADIO,
					radio_nr);
	if (retval < 0) {
		dev_err(&intf->dev, "could not register video device\n");
		goto err_vdev;
	}

	return 0;

err_vdev:
	v4l2_device_unregister(&radio->v4l2_dev);
err_v4l2:
	kfree(radio->buffer);
err_nobuf:
	kfree(radio);
err:
	return retval;
}

module_usb_driver(usb_amradio_driver);