1 /*
2  * A driver for the AverMedia MR 800 USB FM radio. This device plugs
3  * into both the USB and an analog audio input, so this thing
4  * only deals with initialization and frequency setting, the
5  * audio data has to be handled by a sound driver.
6  *
7  * Copyright (c) 2008 Alexey Klimov <klimov.linux@gmail.com>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * This program is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17  * GNU General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License
20  * along with this program; if not, write to the Free Software
21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22  */
23 
24 /*
25  * Big thanks to authors and contributors of dsbr100.c and radio-si470x.c
26  *
27  * When work was looked pretty good, i discover this:
28  * http://av-usbradio.sourceforge.net/index.php
29  * http://sourceforge.net/projects/av-usbradio/
30  * Latest release of theirs project was in 2005.
31  * Probably, this driver could be improved through using their
32  * achievements (specifications given).
33  * Also, Faidon Liambotis <paravoid@debian.org> wrote nice driver for this radio
34  * in 2007. He allowed to use his driver to improve current mr800 radio driver.
35  * http://kerneltrap.org/mailarchive/linux-usb-devel/2007/10/11/342492
36  *
37  * Version 0.01:	First working version.
38  * 			It's required to blacklist AverMedia USB Radio
39  * 			in usbhid/hid-quirks.c
40  * Version 0.10:	A lot of cleanups and fixes: unpluging the device,
41  * 			few mutex locks were added, codinstyle issues, etc.
42  * 			Added stereo support. Thanks to
43  * 			Douglas Schilling Landgraf <dougsland@gmail.com> and
44  * 			David Ellingsworth <david@identd.dyndns.org>
45  * 			for discussion, help and support.
46  * Version 0.11:	Converted to v4l2_device.
47  *
48  * Many things to do:
49  * 	- Correct power management of device (suspend & resume)
50  * 	- Add code for scanning and smooth tuning
51  * 	- Add code for sensitivity value
52  * 	- Correct mistakes
53  * 	- In Japan another FREQ_MIN and FREQ_MAX
54  */
55 
56 /* kernel includes */
57 #include <linux/kernel.h>
58 #include <linux/module.h>
59 #include <linux/init.h>
60 #include <linux/slab.h>
61 #include <linux/input.h>
62 #include <linux/videodev2.h>
63 #include <media/v4l2-device.h>
64 #include <media/v4l2-ioctl.h>
65 #include <linux/usb.h>
66 #include <linux/mutex.h>
67 
68 /* driver and module definitions */
69 #define DRIVER_AUTHOR "Alexey Klimov <klimov.linux@gmail.com>"
70 #define DRIVER_DESC "AverMedia MR 800 USB FM radio driver"
71 #define DRIVER_VERSION "0.1.2"
72 
73 MODULE_AUTHOR(DRIVER_AUTHOR);
74 MODULE_DESCRIPTION(DRIVER_DESC);
75 MODULE_LICENSE("GPL");
76 MODULE_VERSION(DRIVER_VERSION);
77 
78 #define USB_AMRADIO_VENDOR 0x07ca
79 #define USB_AMRADIO_PRODUCT 0xb800
80 
81 /* dev_warn macro with driver name */
82 #define MR800_DRIVER_NAME "radio-mr800"
83 #define amradio_dev_warn(dev, fmt, arg...)				\
84 		dev_warn(dev, MR800_DRIVER_NAME " - " fmt, ##arg)
85 
86 #define amradio_dev_err(dev, fmt, arg...) \
87 		dev_err(dev, MR800_DRIVER_NAME " - " fmt, ##arg)
88 
89 /* Probably USB_TIMEOUT should be modified in module parameter */
90 #define BUFFER_LENGTH 8
91 #define USB_TIMEOUT 500
92 
93 /* Frequency limits in MHz -- these are European values.  For Japanese
94 devices, that would be 76 and 91.  */
95 #define FREQ_MIN  87.5
96 #define FREQ_MAX 108.0
97 #define FREQ_MUL 16000
98 
99 /*
100  * Commands that device should understand
101  * List isn't full and will be updated with implementation of new functions
102  */
103 #define AMRADIO_SET_FREQ	0xa4
104 #define AMRADIO_SET_MUTE	0xab
105 #define AMRADIO_SET_MONO	0xae
106 
107 /* Comfortable defines for amradio_set_mute */
108 #define AMRADIO_START		0x00
109 #define AMRADIO_STOP		0x01
110 
111 /* Comfortable defines for amradio_set_stereo */
112 #define WANT_STEREO		0x00
113 #define WANT_MONO		0x01
114 
115 /* module parameter */
116 static int radio_nr = -1;
117 module_param(radio_nr, int, 0);
118 MODULE_PARM_DESC(radio_nr, "Radio Nr");
119 
120 static int usb_amradio_probe(struct usb_interface *intf,
121 			     const struct usb_device_id *id);
122 static void usb_amradio_disconnect(struct usb_interface *intf);
123 static int usb_amradio_open(struct file *file);
124 static int usb_amradio_close(struct file *file);
125 static int usb_amradio_suspend(struct usb_interface *intf,
126 				pm_message_t message);
127 static int usb_amradio_resume(struct usb_interface *intf);
128 
129 /* Data for one (physical) device */
130 struct amradio_device {
131 	/* reference to USB and video device */
132 	struct usb_device *usbdev;
133 	struct usb_interface *intf;
134 	struct video_device videodev;
135 	struct v4l2_device v4l2_dev;
136 
137 	unsigned char *buffer;
138 	struct mutex lock;	/* buffer locking */
139 	int curfreq;
140 	int stereo;
141 	int muted;
142 	int initialized;
143 };
144 
145 static inline struct amradio_device *to_amradio_dev(struct v4l2_device *v4l2_dev)
146 {
147 	return container_of(v4l2_dev, struct amradio_device, v4l2_dev);
148 }
149 
150 /* USB Device ID List */
151 static struct usb_device_id usb_amradio_device_table[] = {
152 	{USB_DEVICE_AND_INTERFACE_INFO(USB_AMRADIO_VENDOR, USB_AMRADIO_PRODUCT,
153 							USB_CLASS_HID, 0, 0) },
154 	{ }						/* Terminating entry */
155 };
156 
157 MODULE_DEVICE_TABLE(usb, usb_amradio_device_table);
158 
159 /* USB subsystem interface */
160 static struct usb_driver usb_amradio_driver = {
161 	.name			= MR800_DRIVER_NAME,
162 	.probe			= usb_amradio_probe,
163 	.disconnect		= usb_amradio_disconnect,
164 	.suspend		= usb_amradio_suspend,
165 	.resume			= usb_amradio_resume,
166 	.reset_resume		= usb_amradio_resume,
167 	.id_table		= usb_amradio_device_table,
168 	.supports_autosuspend	= 1,
169 };
170 
171 /* switch on/off the radio. Send 8 bytes to device */
172 static int amradio_set_mute(struct amradio_device *radio, char argument)
173 {
174 	int retval;
175 	int size;
176 
177 	radio->buffer[0] = 0x00;
178 	radio->buffer[1] = 0x55;
179 	radio->buffer[2] = 0xaa;
180 	radio->buffer[3] = 0x00;
181 	radio->buffer[4] = AMRADIO_SET_MUTE;
182 	radio->buffer[5] = argument;
183 	radio->buffer[6] = 0x00;
184 	radio->buffer[7] = 0x00;
185 
186 	retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
187 		(void *) (radio->buffer), BUFFER_LENGTH, &size, USB_TIMEOUT);
188 
189 	if (retval < 0 || size != BUFFER_LENGTH) {
190 		amradio_dev_warn(&radio->videodev.dev, "set mute failed\n");
191 		return retval;
192 	}
193 
194 	radio->muted = argument;
195 
196 	return retval;
197 }
198 
199 /* set a frequency, freq is defined by v4l's TUNER_LOW, i.e. 1/16th kHz */
200 static int amradio_setfreq(struct amradio_device *radio, int freq)
201 {
202 	int retval;
203 	int size;
204 	unsigned short freq_send = 0x10 + (freq >> 3) / 25;
205 
206 	radio->buffer[0] = 0x00;
207 	radio->buffer[1] = 0x55;
208 	radio->buffer[2] = 0xaa;
209 	radio->buffer[3] = 0x03;
210 	radio->buffer[4] = AMRADIO_SET_FREQ;
211 	radio->buffer[5] = 0x00;
212 	radio->buffer[6] = 0x00;
213 	radio->buffer[7] = 0x08;
214 
215 	retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
216 		(void *) (radio->buffer), BUFFER_LENGTH, &size, USB_TIMEOUT);
217 
218 	if (retval < 0 || size != BUFFER_LENGTH)
219 		goto out_err;
220 
221 	/* frequency is calculated from freq_send and placed in first 2 bytes */
222 	radio->buffer[0] = (freq_send >> 8) & 0xff;
223 	radio->buffer[1] = freq_send & 0xff;
224 	radio->buffer[2] = 0x01;
225 	radio->buffer[3] = 0x00;
226 	radio->buffer[4] = 0x00;
227 	/* 5 and 6 bytes of buffer already = 0x00 */
228 	radio->buffer[7] = 0x00;
229 
230 	retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
231 		(void *) (radio->buffer), BUFFER_LENGTH, &size, USB_TIMEOUT);
232 
233 	if (retval < 0 || size != BUFFER_LENGTH)
234 		goto out_err;
235 
236 	radio->curfreq = freq;
237 	goto out;
238 
239 out_err:
240 	amradio_dev_warn(&radio->videodev.dev, "set frequency failed\n");
241 out:
242 	return retval;
243 }
244 
245 static int amradio_set_stereo(struct amradio_device *radio, char argument)
246 {
247 	int retval;
248 	int size;
249 
250 	radio->buffer[0] = 0x00;
251 	radio->buffer[1] = 0x55;
252 	radio->buffer[2] = 0xaa;
253 	radio->buffer[3] = 0x00;
254 	radio->buffer[4] = AMRADIO_SET_MONO;
255 	radio->buffer[5] = argument;
256 	radio->buffer[6] = 0x00;
257 	radio->buffer[7] = 0x00;
258 
259 	retval = usb_bulk_msg(radio->usbdev, usb_sndintpipe(radio->usbdev, 2),
260 		(void *) (radio->buffer), BUFFER_LENGTH, &size, USB_TIMEOUT);
261 
262 	if (retval < 0 || size != BUFFER_LENGTH) {
263 		amradio_dev_warn(&radio->videodev.dev, "set stereo failed\n");
264 		return retval;
265 	}
266 
267 	if (argument == WANT_STEREO)
268 		radio->stereo = 1;
269 	else
270 		radio->stereo = 0;
271 
272 	return retval;
273 }
274 
275 /* Handle unplugging the device.
276  * We call video_unregister_device in any case.
277  * The last function called in this procedure is
278  * usb_amradio_device_release.
279  */
280 static void usb_amradio_disconnect(struct usb_interface *intf)
281 {
282 	struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));
283 
284 	mutex_lock(&radio->lock);
285 	/* increase the device node's refcount */
286 	get_device(&radio->videodev.dev);
287 	v4l2_device_disconnect(&radio->v4l2_dev);
288 	video_unregister_device(&radio->videodev);
289 	mutex_unlock(&radio->lock);
290 	/* decrease the device node's refcount, allowing it to be released */
291 	put_device(&radio->videodev.dev);
292 }
293 
294 /* vidioc_querycap - query device capabilities */
295 static int vidioc_querycap(struct file *file, void *priv,
296 					struct v4l2_capability *v)
297 {
298 	struct amradio_device *radio = file->private_data;
299 
300 	strlcpy(v->driver, "radio-mr800", sizeof(v->driver));
301 	strlcpy(v->card, "AverMedia MR 800 USB FM Radio", sizeof(v->card));
302 	usb_make_path(radio->usbdev, v->bus_info, sizeof(v->bus_info));
303 	v->capabilities = V4L2_CAP_TUNER;
304 	return 0;
305 }
306 
307 /* vidioc_g_tuner - get tuner attributes */
308 static int vidioc_g_tuner(struct file *file, void *priv,
309 				struct v4l2_tuner *v)
310 {
311 	struct amradio_device *radio = file->private_data;
312 	int retval;
313 
314 	if (v->index > 0)
315 		return -EINVAL;
316 
317 /* TODO: Add function which look is signal stereo or not
318  * 	amradio_getstat(radio);
319  */
320 
321 /* we call amradio_set_stereo to set radio->stereo
322  * Honestly, amradio_getstat should cover this in future and
323  * amradio_set_stereo shouldn't be here
324  */
325 	retval = amradio_set_stereo(radio, WANT_STEREO);
326 
327 	strcpy(v->name, "FM");
328 	v->type = V4L2_TUNER_RADIO;
329 	v->rangelow = FREQ_MIN * FREQ_MUL;
330 	v->rangehigh = FREQ_MAX * FREQ_MUL;
331 	v->rxsubchans = V4L2_TUNER_SUB_MONO | V4L2_TUNER_SUB_STEREO;
332 	v->capability = V4L2_TUNER_CAP_LOW;
333 	if (radio->stereo)
334 		v->audmode = V4L2_TUNER_MODE_STEREO;
335 	else
336 		v->audmode = V4L2_TUNER_MODE_MONO;
337 	v->signal = 0xffff;     /* Can't get the signal strength, sad.. */
338 	v->afc = 0; /* Don't know what is this */
339 
340 	return retval;
341 }
342 
343 /* vidioc_s_tuner - set tuner attributes */
344 static int vidioc_s_tuner(struct file *file, void *priv,
345 				struct v4l2_tuner *v)
346 {
347 	struct amradio_device *radio = file->private_data;
348 	int retval = -EINVAL;
349 
350 	if (v->index > 0)
351 		return -EINVAL;
352 
353 	/* mono/stereo selector */
354 	switch (v->audmode) {
355 	case V4L2_TUNER_MODE_MONO:
356 		retval = amradio_set_stereo(radio, WANT_MONO);
357 		break;
358 	case V4L2_TUNER_MODE_STEREO:
359 		retval = amradio_set_stereo(radio, WANT_STEREO);
360 		break;
361 	}
362 
363 	return retval;
364 }
365 
366 /* vidioc_s_frequency - set tuner radio frequency */
367 static int vidioc_s_frequency(struct file *file, void *priv,
368 				struct v4l2_frequency *f)
369 {
370 	struct amradio_device *radio = file->private_data;
371 
372 	if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
373 		return -EINVAL;
374 	return amradio_setfreq(radio, f->frequency);
375 }
376 
377 /* vidioc_g_frequency - get tuner radio frequency */
378 static int vidioc_g_frequency(struct file *file, void *priv,
379 				struct v4l2_frequency *f)
380 {
381 	struct amradio_device *radio = file->private_data;
382 
383 	if (f->tuner != 0)
384 		return -EINVAL;
385 	f->type = V4L2_TUNER_RADIO;
386 	f->frequency = radio->curfreq;
387 
388 	return 0;
389 }
390 
391 /* vidioc_queryctrl - enumerate control items */
392 static int vidioc_queryctrl(struct file *file, void *priv,
393 				struct v4l2_queryctrl *qc)
394 {
395 	switch (qc->id) {
396 	case V4L2_CID_AUDIO_MUTE:
397 		return v4l2_ctrl_query_fill(qc, 0, 1, 1, 1);
398 	}
399 
400 	return -EINVAL;
401 }
402 
403 /* vidioc_g_ctrl - get the value of a control */
404 static int vidioc_g_ctrl(struct file *file, void *priv,
405 				struct v4l2_control *ctrl)
406 {
407 	struct amradio_device *radio = file->private_data;
408 
409 	switch (ctrl->id) {
410 	case V4L2_CID_AUDIO_MUTE:
411 		ctrl->value = radio->muted;
412 		return 0;
413 	}
414 
415 	return -EINVAL;
416 }
417 
418 /* vidioc_s_ctrl - set the value of a control */
419 static int vidioc_s_ctrl(struct file *file, void *priv,
420 				struct v4l2_control *ctrl)
421 {
422 	struct amradio_device *radio = file->private_data;
423 	int retval = -EINVAL;
424 
425 	switch (ctrl->id) {
426 	case V4L2_CID_AUDIO_MUTE:
427 		if (ctrl->value)
428 			retval = amradio_set_mute(radio, AMRADIO_STOP);
429 		else
430 			retval = amradio_set_mute(radio, AMRADIO_START);
431 
432 		break;
433 	}
434 
435 	return retval;
436 }
437 
438 /* vidioc_g_audio - get audio attributes */
439 static int vidioc_g_audio(struct file *file, void *priv,
440 				struct v4l2_audio *a)
441 {
442 	if (a->index > 1)
443 		return -EINVAL;
444 
445 	strcpy(a->name, "Radio");
446 	a->capability = V4L2_AUDCAP_STEREO;
447 	return 0;
448 }
449 
450 /* vidioc_s_audio - set audio attributes  */
451 static int vidioc_s_audio(struct file *file, void *priv,
452 					struct v4l2_audio *a)
453 {
454 	if (a->index != 0)
455 		return -EINVAL;
456 	return 0;
457 }
458 
459 /* vidioc_g_input - get input */
460 static int vidioc_g_input(struct file *filp, void *priv, unsigned int *i)
461 {
462 	*i = 0;
463 	return 0;
464 }
465 
466 /* vidioc_s_input - set input */
467 static int vidioc_s_input(struct file *filp, void *priv, unsigned int i)
468 {
469 	if (i != 0)
470 		return -EINVAL;
471 	return 0;
472 }
473 
474 static int usb_amradio_init(struct amradio_device *radio)
475 {
476 	int retval;
477 
478 	retval = amradio_set_mute(radio, AMRADIO_STOP);
479 	if (retval)
480 		goto out_err;
481 
482 	retval = amradio_set_stereo(radio, WANT_STEREO);
483 	if (retval)
484 		goto out_err;
485 
486 	radio->initialized = 1;
487 	goto out;
488 
489 out_err:
490 	amradio_dev_err(&radio->videodev.dev, "initialization failed\n");
491 out:
492 	return retval;
493 }
494 
495 /* open device - amradio_start() and amradio_setfreq() */
496 static int usb_amradio_open(struct file *file)
497 {
498 	struct amradio_device *radio = video_drvdata(file);
499 	int retval;
500 
501 	file->private_data = radio;
502 	retval = usb_autopm_get_interface(radio->intf);
503 	if (retval)
504 		return retval;
505 
506 	if (unlikely(!radio->initialized)) {
507 		retval = usb_amradio_init(radio);
508 		if (retval)
509 			usb_autopm_put_interface(radio->intf);
510 	}
511 	return retval;
512 }
513 
514 /*close device */
515 static int usb_amradio_close(struct file *file)
516 {
517 	struct amradio_device *radio = file->private_data;
518 
519 	if (video_is_registered(&radio->videodev))
520 		usb_autopm_put_interface(radio->intf);
521 	return 0;
522 }
523 
524 /* Suspend device - stop device. Need to be checked and fixed */
525 static int usb_amradio_suspend(struct usb_interface *intf, pm_message_t message)
526 {
527 	struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));
528 
529 	mutex_lock(&radio->lock);
530 	if (!radio->muted && radio->initialized) {
531 		amradio_set_mute(radio, AMRADIO_STOP);
532 		radio->muted = 0;
533 	}
534 	mutex_unlock(&radio->lock);
535 
536 	dev_info(&intf->dev, "going into suspend..\n");
537 	return 0;
538 }
539 
540 /* Resume device - start device. Need to be checked and fixed */
541 static int usb_amradio_resume(struct usb_interface *intf)
542 {
543 	struct amradio_device *radio = to_amradio_dev(usb_get_intfdata(intf));
544 
545 	mutex_lock(&radio->lock);
546 	if (unlikely(!radio->initialized))
547 		goto unlock;
548 
549 	if (radio->stereo)
550 		amradio_set_stereo(radio, WANT_STEREO);
551 	else
552 		amradio_set_stereo(radio, WANT_MONO);
553 
554 	amradio_setfreq(radio, radio->curfreq);
555 
556 	if (!radio->muted)
557 		amradio_set_mute(radio, AMRADIO_START);
558 
559 unlock:
560 	mutex_unlock(&radio->lock);
561 
562 	dev_info(&intf->dev, "coming out of suspend..\n");
563 	return 0;
564 }
565 
566 /* File system interface */
567 static const struct v4l2_file_operations usb_amradio_fops = {
568 	.owner		= THIS_MODULE,
569 	.open		= usb_amradio_open,
570 	.release	= usb_amradio_close,
571 	.unlocked_ioctl	= video_ioctl2,
572 };
573 
574 static const struct v4l2_ioctl_ops usb_amradio_ioctl_ops = {
575 	.vidioc_querycap    = vidioc_querycap,
576 	.vidioc_g_tuner     = vidioc_g_tuner,
577 	.vidioc_s_tuner     = vidioc_s_tuner,
578 	.vidioc_g_frequency = vidioc_g_frequency,
579 	.vidioc_s_frequency = vidioc_s_frequency,
580 	.vidioc_queryctrl   = vidioc_queryctrl,
581 	.vidioc_g_ctrl      = vidioc_g_ctrl,
582 	.vidioc_s_ctrl      = vidioc_s_ctrl,
583 	.vidioc_g_audio     = vidioc_g_audio,
584 	.vidioc_s_audio     = vidioc_s_audio,
585 	.vidioc_g_input     = vidioc_g_input,
586 	.vidioc_s_input     = vidioc_s_input,
587 };
588 
589 static void usb_amradio_video_device_release(struct video_device *videodev)
590 {
591 	struct amradio_device *radio = video_get_drvdata(videodev);
592 
593 	/* free rest memory */
594 	kfree(radio->buffer);
595 	kfree(radio);
596 }
597 
598 /* check if the device is present and register with v4l and usb if it is */
599 static int usb_amradio_probe(struct usb_interface *intf,
600 				const struct usb_device_id *id)
601 {
602 	struct amradio_device *radio;
603 	int retval = 0;
604 
605 	radio = kzalloc(sizeof(struct amradio_device), GFP_KERNEL);
606 
607 	if (!radio) {
608 		dev_err(&intf->dev, "kmalloc for amradio_device failed\n");
609 		retval = -ENOMEM;
610 		goto err;
611 	}
612 
613 	radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);
614 
615 	if (!radio->buffer) {
616 		dev_err(&intf->dev, "kmalloc for radio->buffer failed\n");
617 		retval = -ENOMEM;
618 		goto err_nobuf;
619 	}
620 
621 	retval = v4l2_device_register(&intf->dev, &radio->v4l2_dev);
622 	if (retval < 0) {
623 		dev_err(&intf->dev, "couldn't register v4l2_device\n");
624 		goto err_v4l2;
625 	}
626 
627 	mutex_init(&radio->lock);
628 
629 	strlcpy(radio->videodev.name, radio->v4l2_dev.name,
630 		sizeof(radio->videodev.name));
631 	radio->videodev.v4l2_dev = &radio->v4l2_dev;
632 	radio->videodev.fops = &usb_amradio_fops;
633 	radio->videodev.ioctl_ops = &usb_amradio_ioctl_ops;
634 	radio->videodev.release = usb_amradio_video_device_release;
635 	radio->videodev.lock = &radio->lock;
636 
637 	radio->usbdev = interface_to_usbdev(intf);
638 	radio->intf = intf;
639 	radio->curfreq = 95.16 * FREQ_MUL;
640 
641 	video_set_drvdata(&radio->videodev, radio);
642 
643 	retval = video_register_device(&radio->videodev, VFL_TYPE_RADIO,
644 					radio_nr);
645 	if (retval < 0) {
646 		dev_err(&intf->dev, "could not register video device\n");
647 		goto err_vdev;
648 	}
649 
650 	return 0;
651 
652 err_vdev:
653 	v4l2_device_unregister(&radio->v4l2_dev);
654 err_v4l2:
655 	kfree(radio->buffer);
656 err_nobuf:
657 	kfree(radio);
658 err:
659 	return retval;
660 }
661 
662 static int __init amradio_init(void)
663 {
664 	int retval = usb_register(&usb_amradio_driver);
665 
666 	pr_info(KBUILD_MODNAME
667 		": version " DRIVER_VERSION " " DRIVER_DESC "\n");
668 
669 	if (retval)
670 		pr_err(KBUILD_MODNAME
671 			": usb_register failed. Error number %d\n", retval);
672 
673 	return retval;
674 }
675 
676 static void __exit amradio_exit(void)
677 {
678 	usb_deregister(&usb_amradio_driver);
679 }
680 
681 module_init(amradio_init);
682 module_exit(amradio_exit);
683 
684