summaryrefslogtreecommitdiff
path: root/drivers/media/radio/radio-si470x.c
blob: eccbc750e1408e7900c9bb7f348bbae2aeedd093 (plain)
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
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
/*
 *  drivers/media/radio/radio-si470x.c
 *
 *  Driver for USB radios for the Silicon Labs Si470x FM Radio Receivers:
 *   - Silicon Labs USB FM Radio Reference Design
 *   - ADS/Tech FM Radio Receiver (formerly Instant FM Music) (RDX-155-EF)
 *
 *  Copyright (c) 2007 Tobias Lorenz <tobias.lorenz@gmx.net>
 *
 * 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
 */


/*
 * History:
 * 2008-01-12	Tobias Lorenz <tobias.lorenz@gmx.net>
 *		Version 1.0.0
 *		- First working version
 * 2008-01-13   Tobias Lorenz <tobias.lorenz@gmx.net>
 *              Version 1.0.1
 *		- Improved error handling, every function now returns errno
 *		- Improved multi user access (start/mute/stop)
 *		- Channel doesn't get lost anymore after start/mute/stop
 *		- RDS support added (polling mode via interrupt EP 1)
 *		- marked default module parameters with *value*
 *		- switched from bit structs to bit masks
 *		- header file cleaned and integrated
 * 2008-01-14	Tobias Lorenz <tobias.lorenz@gmx.net>
 * 		Version 1.0.2
 * 		- hex values are now lower case
 * 		- commented USB ID for ADS/Tech moved on todo list
 * 		- blacklisted si470x in hid-quirks.c
 * 		- rds buffer handling functions integrated into *_work, *_read
 * 		- rds_command in si470x_poll exchanged against simple retval
 * 		- check for firmware version 15
 * 		- code order and prototypes still remain the same
 * 		- spacing and bottom of band codes remain the same
 *
 * ToDo:
 * - check USB Vendor/Product ID for ADS/Tech FM Radio Receiver
 *   (formerly Instant FM Music) (RDX-155-EF) is 06e1:a155
 * - add seeking support
 * - add firmware download/update support
 * - add possibility to switch off RDS
 * - RDS support: interrupt mode, instead of polling
 * - add LED status output
 */

/* driver definitions */
#define DRIVER_AUTHOR "Tobias Lorenz <tobias.lorenz@gmx.net>"
#define DRIVER_NAME "radio-si470x"
#define DRIVER_VERSION KERNEL_VERSION(1, 0, 2)
#define DRIVER_CARD "Silicon Labs Si470x FM Radio Receiver"
#define DRIVER_DESC "USB radio driver for Si470x FM Radio Receivers"


/* 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-common.h>
#include <linux/usb.h>
#include <linux/hid.h>
#include <linux/version.h>
#include <media/rds.h>


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

/* Spacing (kHz) */
/* 0: 200 kHz (USA, Australia) */
/* 1: 100 kHz (Europe, Japan) */
/* 2:  50 kHz */
static int space = 2;
module_param(space, int, 0);
MODULE_PARM_DESC(radio_nr, "Spacing: 0=200kHz 1=100kHz *2=50kHz*");

/* Bottom of Band (MHz) */
/* 0: 87.5 - 108 MHz (USA, Europe)*/
/* 1: 76   - 108 MHz (Japan wide band) */
/* 2: 76   -  90 MHz (Japan) */
static int band = 1;
module_param(band, int, 0);
MODULE_PARM_DESC(radio_nr, "Band: 0=87.5..108MHz *1=76..108MHz* 2=76..90MHz");

/* De-emphasis */
/* 0: 75 us (USA) */
/* 1: 50 us (Europe, Australia, Japan) */
static int de = 1;
module_param(de, int, 0);
MODULE_PARM_DESC(radio_nr, "De-emphasis: 0=75us *1=50us*");

/* USB timeout */
static int usb_timeout = 500;
module_param(usb_timeout, int, 0);
MODULE_PARM_DESC(usb_timeout, "USB timeout (ms): *500*");

/* Seek retries */
static int seek_retries = 100;
module_param(seek_retries, int, 0);
MODULE_PARM_DESC(seek_retries, "Seek retries: *100*");

/* RDS buffer blocks */
static int rds_buf = 100;
module_param(rds_buf, int, 0);
MODULE_PARM_DESC(rds_buf, "RDS buffer entries: *100*");

/* RDS maximum block errors */
static int max_rds_errors = 1;
/* 0 means   0  errors requiring correction */
/* 1 means 1-2  errors requiring correction (used by original USBRadio.exe) */
/* 2 means 3-5  errors requiring correction */
/* 3 means   6+ errors or errors in checkword, correction not possible */
module_param(max_rds_errors, int, 0);
MODULE_PARM_DESC(max_rds_errors, "RDS maximum block errors: *1*");

/* RDS poll frequency */
static int rds_poll_time = 40;
/* 40 is used by the original USBRadio.exe */
/* 75 should be okay */
/* 80 is the usual RDS receive interval */
module_param(rds_poll_time, int, 0);
MODULE_PARM_DESC(rds_poll_time, "RDS poll time (ms): *40*");



/**************************************************************************
 * Register Definitions
 **************************************************************************/
#define FMRADIO_REGISTER_SIZE	2	/* 16 register bit width */
#define FMRADIO_REGISTER_NUM	16	/* DEVICEID   ... RDSD */
#define RDS_REGISTER_NUM	6	/* STATUSRSSI ... RDSD */

#define DEVICEID		0	/* Device ID */
#define DEVICEID_PN		0xf000	/* bits 15..12: Part Number */
#define DEVICEID_MFGID		0x0fff	/* bits 11..00: Manufacturer ID */

#define CHIPID			1	/* Chip ID */
#define CHIPID_REV		0xfc00	/* bits 15..10: Chip Version */
#define CHIPID_DEV		0x0200	/* bits 09..09: Device */
#define CHIPID_FIRMWARE		0x01ff	/* bits 08..00: Firmware Version */

#define POWERCFG		2	/* Power Configuration */
#define POWERCFG_DSMUTE		0x8000	/* bits 15..15: Softmute Disable */
#define POWERCFG_DMUTE		0x4000	/* bits 14..14: Mute Disable */
#define POWERCFG_MONO		0x2000	/* bits 13..13: Mono Select */
#define POWERCFG_RDSM		0x0800	/* bits 11..11: RDS Mode (Si4701 only) */
#define POWERCFG_SKMODE		0x0400	/* bits 10..10: Seek Mode */
#define POWERCFG_SEEKUP		0x0200	/* bits 09..09: Seek Direction */
#define POWERCFG_SEEK		0x0100	/* bits 08..08: Seek */
#define POWERCFG_DISABLE	0x0040	/* bits 06..06: Powerup Disable */
#define POWERCFG_ENABLE		0x0001	/* bits 00..00: Powerup Enable */

#define CHANNEL			3	/* Channel */
#define CHANNEL_TUNE		0x8000	/* bits 15..15: Tune */
#define CHANNEL_CHAN		0x03ff	/* bits 09..00: Channel Select */

#define SYSCONFIG1		4	/* System Configuration 1 */
#define SYSCONFIG1_RDSIEN	0x8000	/* bits 15..15: RDS Interrupt Enable (Si4701 only) */
#define SYSCONFIG1_STCIEN	0x4000	/* bits 14..14: Seek/Tune Complete Interrupt Enable */
#define SYSCONFIG1_RDS		0x1000	/* bits 12..12: RDS Enable (Si4701 only) */
#define SYSCONFIG1_DE		0x0800	/* bits 11..11: De-emphasis (0=75us 1=50us) */
#define SYSCONFIG1_AGCD		0x0400	/* bits 10..10: AGC Disable */
#define SYSCONFIG1_BLNDADJ	0x00c0	/* bits 07..06: Stereo/Mono Blend Level Adjustment */
#define SYSCONFIG1_GPIO3	0x0030	/* bits 05..04: General Purpose I/O 3 */
#define SYSCONFIG1_GPIO2	0x000c	/* bits 03..02: General Purpose I/O 2 */
#define SYSCONFIG1_GPIO1	0x0003	/* bits 01..00: General Purpose I/O 1 */

#define SYSCONFIG2		5	/* System Configuration 2 */
#define SYSCONFIG2_SEEKTH	0xff00	/* bits 15..08: RSSI Seek Threshold */
#define SYSCONFIG2_BAND		0x0080	/* bits 07..06: Band Select */
#define SYSCONFIG2_SPACE	0x0030	/* bits 05..04: Channel Spacing */
#define SYSCONFIG2_VOLUME	0x000f	/* bits 03..00: Volume */

#define SYSCONFIG3		6	/* System Configuration 3 */
#define SYSCONFIG3_SMUTER	0xc000	/* bits 15..14: Softmute Attack/Recover Rate */
#define SYSCONFIG3_SMUTEA	0x3000	/* bits 13..12: Softmute Attenuation */
#define SYSCONFIG3_SKSNR	0x00f0	/* bits 07..04: Seek SNR Threshold */
#define SYSCONFIG3_SKCNT	0x000f	/* bits 03..00: Seek FM Impulse Detection Threshold */

#define TEST1			7	/* Test 1 */
#define TEST1_AHIZEN		0x4000	/* bits 14..14: Audio High-Z Enable */

#define TEST2			8	/* Test 2 */
/* TEST2 only contains reserved bits */

#define BOOTCONFIG		9	/* Boot Configuration */
/* BOOTCONFIG only contains reserved bits */

#define STATUSRSSI		10	/* Status RSSI */
#define STATUSRSSI_RDSR		0x8000	/* bits 15..15: RDS Ready (Si4701 only) */
#define STATUSRSSI_STC		0x4000	/* bits 14..14: Seek/Tune Complete */
#define STATUSRSSI_SF		0x2000	/* bits 13..13: Seek Fail/Band Limit */
#define STATUSRSSI_AFCRL	0x1000	/* bits 12..12: AFC Rail */
#define STATUSRSSI_RDSS		0x0800	/* bits 11..11: RDS Synchronized (Si4701 only) */
#define STATUSRSSI_BLERA	0x0600	/* bits 10..09: RDS Block A Errors (Si4701 only) */
#define STATUSRSSI_ST		0x0100	/* bits 08..08: Stereo Indicator */
#define STATUSRSSI_RSSI		0x00ff	/* bits 07..00: RSSI (Received Signal Strength Indicator) */

#define READCHAN		11	/* Read Channel */
#define READCHAN_BLERB		0xc000	/* bits 15..14: RDS Block D Errors (Si4701 only) */
#define READCHAN_BLERC		0x3000	/* bits 13..12: RDS Block C Errors (Si4701 only) */
#define READCHAN_BLERD		0x0c00	/* bits 11..10: RDS Block B Errors (Si4701 only) */
#define READCHAN_READCHAN	0x03ff	/* bits 09..00: Read Channel */

#define RDSA			12	/* RDSA */
#define RDSA_RDSA		0xffff	/* bits 15..00: RDS Block A Data (Si4701 only) */

#define RDSB			13	/* RDSB */
#define RDSB_RDSB		0xffff	/* bits 15..00: RDS Block B Data (Si4701 only) */

#define RDSC			14	/* RDSC */
#define RDSC_RDSC		0xffff	/* bits 15..00: RDS Block C Data (Si4701 only) */

#define RDSD			15	/* RDSD */
#define RDSD_RDSD		0xffff	/* bits 15..00: RDS Block D Data (Si4701 only) */



/**************************************************************************
 * USB HID reports
 **************************************************************************/

/* Reports 1-16 give direct read/write access to the 16 Si470x registers */
/* with the (REPORT_ID - 1) corresponding to the register address across USB */
/* endpoint 0 using GET_REPORT and SET_REPORT */
#define REGISTER_REPORT_SIZE	(FMRADIO_REGISTER_SIZE + 1)
#define REGISTER_REPORT(reg)	((reg) + 1)

/* Report 17 gives direct read/write access to the entire Si470x register */
/* map across endpoint 0 using GET_REPORT and SET_REPORT */
#define ENTIRE_REPORT_SIZE	(FMRADIO_REGISTER_NUM * FMRADIO_REGISTER_SIZE + 1)
#define ENTIRE_REPORT		17

/* Report 18 is used to send the lowest 6 Si470x registers up the HID */
/* interrupt endpoint 1 to Windows every 20 milliseconds for status */
#define RDS_REPORT_SIZE		(RDS_REGISTER_NUM * FMRADIO_REGISTER_SIZE + 1)
#define RDS_REPORT		18

/* Report 19: LED state */
#define LED_REPORT_SIZE		3
#define LED_REPORT		19

/* Report 19: stream */
#define STREAM_REPORT_SIZE	3
#define	STREAM_REPORT		19

/* Report 20: scratch */
#define SCRATCH_PAGE_SIZE	63
#define SCRATCH_REPORT_SIZE	(SCRATCH_PAGE_SIZE + 1)
#define SCRATCH_REPORT		20

/* Reports 19-22: flash upgrade of the C8051F321 */
#define WRITE_REPORT		19
#define FLASH_REPORT		20
#define CRC_REPORT		21
#define RESPONSE_REPORT		22

/* Report 23: currently unused, but can accept 60 byte reports on the HID */
/* interrupt out endpoint 2 every 1 millisecond */
#define UNUSED_REPORT		23



/**************************************************************************
 * software/hardware versions
 **************************************************************************/
#define FMRADIO_SW_VERSION_NOT_BOOTLOADABLE	6
#define FMRADIO_SW_VERSION			7
#define FMRADIO_SW_VERSION_CURRENT		15
#define FMRADIO_HW_VERSION			1

#define SCRATCH_PAGE_SW_VERSION	1
#define SCRATCH_PAGE_HW_VERSION	2



/**************************************************************************
 * LED State definitions
 **************************************************************************/
#define LED_COMMAND		0x35

#define NO_CHANGE_LED		0x00
#define ALL_COLOR_LED		0x01	/* streaming state */
#define BLINK_GREEN_LED		0x02	/* connect state */
#define BLINK_RED_LED		0x04
#define BLINK_ORANGE_LED	0x10	/* disconnect state */
#define SOLID_GREEN_LED		0x20	/* tuning/seeking state */
#define SOLID_RED_LED		0x40	/* bootload state */
#define SOLID_ORANGE_LED	0x80



/**************************************************************************
 * Stream State definitions
 **************************************************************************/
#define STREAM_COMMAND	0x36
#define STREAM_VIDPID	0x00
#define STREAM_AUDIO	0xff



/**************************************************************************
 * bootloader / flash commands
 **************************************************************************/

/* Unique ID sent to bootloader and required to put into a bootload state */
#define UNIQUE_BL_ID		0x34

/* Mask for the flash data */
#define FLASH_DATA_MASK		0x55

/* Bootloader commands */
#define GET_SW_VERSION_COMMAND	0x00
#define	SET_PAGE_COMMAND	0x01
#define ERASE_PAGE_COMMAND	0x02
#define WRITE_PAGE_COMMAND	0x03
#define CRC_ON_PAGE_COMMAND	0x04
#define READ_FLASH_BYTE_COMMAND	0x05
#define RESET_DEVICE_COMMAND	0x06
#define GET_HW_VERSION_COMMAND	0x07
#define BLANK			0xff

/* Bootloader command responses */
#define COMMAND_OK		0x01
#define COMMAND_FAILED		0x02
#define COMMAND_PENDING		0x03

/* Buffer sizes */
#define COMMAND_BUFFER_SIZE	4
#define RESPONSE_BUFFER_SIZE	2
#define FLASH_BUFFER_SIZE	64
#define CRC_BUFFER_SIZE		3



/**************************************************************************
 * Driver private definitions
 **************************************************************************/

/* private data */
struct si470x_device {
	/* reference to USB and video device */
	struct usb_device *usbdev;
	struct video_device *videodev;

	/* are these really necessary ? */
	int users;

	/* report buffer (maximum 64 bytes) */
	unsigned char buf[64];

	/* Silabs internal registers (0..15) */
	unsigned short registers[FMRADIO_REGISTER_NUM];

	/* RDS receive buffer */
	struct work_struct work;
	struct timer_list timer;
	spinlock_t lock;
	unsigned char *buffer;
	unsigned int buf_size;
	unsigned int rd_index;
	unsigned int wr_index;
	unsigned int block_count;
	unsigned char last_blocknum;
	wait_queue_head_t read_queue;
	int data_available_for_read;
};

/* register acccess functions */
static int si470x_get_report(struct si470x_device *radio, int size);
static int si470x_set_report(struct si470x_device *radio, int size);
static int si470x_get_register(struct si470x_device *radio, int regnr);
static int si470x_set_register(struct si470x_device *radio, int regnr);
static int si470x_get_all_registers(struct si470x_device *radio);
static int si470x_get_rds_registers(struct si470x_device *radio);

/* high-level functions */
static int si470x_start(struct si470x_device *radio);
static int si470x_stop(struct si470x_device *radio);
static int si470x_set_chan(struct si470x_device *radio, int chan);
static int si470x_get_freq(struct si470x_device *radio);
static int si470x_set_freq(struct si470x_device *radio, int freq);

/* RDS functions */
static void si470x_rds(struct si470x_device *radio);
static void si470x_timer(unsigned long data);
static void si470x_work(struct work_struct *work);



/**************************************************************************
 * USB interface definitions
 **************************************************************************/

/* USB device ID list (Vendor, Product, Class, SubClass, Protocol) */
static struct usb_device_id si470x_usb_driver_id_table[] = {
	/* Silicon Labs USB FM Radio Reference Design */
	{ USB_DEVICE_AND_INTERFACE_INFO(0x10c4, 0x818a, USB_CLASS_HID, 0, 0) },
	/* Terminating entry */
	{ }
};
MODULE_DEVICE_TABLE (usb, si470x_usb_driver_id_table);

/* USB driver functions */
static int si470x_usb_driver_probe(struct usb_interface *intf,
		const struct usb_device_id *id);
static void si470x_usb_driver_disconnect(struct usb_interface *intf);

/* USB driver interface */
static struct usb_driver si470x_usb_driver = {
	.name		= DRIVER_NAME,
	.probe		= si470x_usb_driver_probe,
	.disconnect	= si470x_usb_driver_disconnect,
	.id_table	= si470x_usb_driver_id_table,
};



/**************************************************************************
 * Video4Linux interface definitions
 **************************************************************************/

/* The frequency is set in units of 62.5 Hz when using V4L2_TUNER_CAP_LOW, */
/* 62.5 kHz otherwise. */
/* The tuner is able to have a channel spacing of 50, 100 or 200 kHz. */
/* tuner->capability is therefore set to V4L2_TUNER_CAP_LOW */
/* The FREQ_MUL is then: 1 MHz / 62.5 Hz = 16000 */
#define FREQ_MUL (1000000 / 62.5)

/* File operations functions */
static ssize_t si470x_fops_read(struct file *file, char __user *buf,
		size_t count, loff_t *ppos);
static unsigned int si470x_fops_poll(struct file *file,
		struct poll_table_struct *pts);
static int si470x_fops_open(struct inode *inode, struct file *file);
static int si470x_fops_release(struct inode *inode, struct file *file);

/* File operations interface */
static const struct file_operations si470x_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.read		= si470x_fops_read,
	.poll		= si470x_fops_poll,
	.ioctl		= video_ioctl2,
	.compat_ioctl	= v4l_compat_ioctl32,
	.open		= si470x_fops_open,
	.release	= si470x_fops_release,
};

/* Video device functions */
static int si470x_vidioc_querycap(struct file *file, void *priv,
		struct v4l2_capability *capability);
static int si470x_vidioc_g_input(struct file *file, void *priv,
		unsigned int *i);
static int si470x_vidioc_s_input(struct file *file, void *priv,
		unsigned int i);
static int si470x_vidioc_queryctrl(struct file *file, void *priv,
		struct v4l2_queryctrl *qc);
static int si470x_vidioc_g_ctrl(struct file *file, void *priv,
		struct v4l2_control *ctrl);
static int si470x_vidioc_s_ctrl(struct file *file, void *priv,
		struct v4l2_control *ctrl);
static int si470x_vidioc_g_audio(struct file *file, void *priv,
		struct v4l2_audio *audio);
static int si470x_vidioc_s_audio(struct file *file, void *priv,
		struct v4l2_audio *audio);
static int si470x_vidioc_g_tuner(struct file *file, void *priv,
		struct v4l2_tuner *tuner);
static int si470x_vidioc_s_tuner(struct file *file, void *priv,
		struct v4l2_tuner *tuner);
static int si470x_vidioc_g_frequency(struct file *file, void *priv,
		struct v4l2_frequency *freq);
static int si470x_vidioc_s_frequency(struct file *file, void *priv,
		struct v4l2_frequency *freq);

/* Video device interface */
static struct video_device si470x_viddev_template = {
	.fops			= &si470x_fops,
	.name			= DRIVER_NAME,
	.type			= VID_TYPE_TUNER,
	.release		= video_device_release,
	.vidioc_querycap	= si470x_vidioc_querycap,
	.vidioc_g_input		= si470x_vidioc_g_input,
	.vidioc_s_input		= si470x_vidioc_s_input,
	.vidioc_queryctrl	= si470x_vidioc_queryctrl,
	.vidioc_g_ctrl		= si470x_vidioc_g_ctrl,
	.vidioc_s_ctrl		= si470x_vidioc_s_ctrl,
	.vidioc_g_audio		= si470x_vidioc_g_audio,
	.vidioc_s_audio		= si470x_vidioc_s_audio,
	.vidioc_g_tuner		= si470x_vidioc_g_tuner,
	.vidioc_s_tuner		= si470x_vidioc_s_tuner,
	.vidioc_g_frequency	= si470x_vidioc_g_frequency,
	.vidioc_s_frequency	= si470x_vidioc_s_frequency,
	.owner			= THIS_MODULE,
};

/* Query control */
static struct v4l2_queryctrl radio_queryctrl[] = {
/* HINT: the disabled controls are only here to satify kradio and such apps */
	{
		.id		= V4L2_CID_AUDIO_VOLUME,
		.type		= V4L2_CTRL_TYPE_INTEGER,
		.name		= "Volume",
		.minimum	= 0,
		.maximum	= 15,
		.step		= 1,
		.default_value	= 15,
	},
	{
		.id		= V4L2_CID_AUDIO_BALANCE,
		.flags		= V4L2_CTRL_FLAG_DISABLED,
	},
	{
		.id		= V4L2_CID_AUDIO_BASS,
		.flags		= V4L2_CTRL_FLAG_DISABLED,
	},
	{
		.id		= V4L2_CID_AUDIO_TREBLE,
		.flags		= V4L2_CTRL_FLAG_DISABLED,
	},
	{
		.id		= V4L2_CID_AUDIO_MUTE,
		.type		= V4L2_CTRL_TYPE_BOOLEAN,
		.name		= "Mute",
		.minimum	= 0,
		.maximum	= 1,
		.step		= 1,
		.default_value	= 1,
	},
	{
		.id		= V4L2_CID_AUDIO_LOUDNESS,
		.flags		= V4L2_CTRL_FLAG_DISABLED,
	},
};



/**************************************************************************
 * Driver private functions
 **************************************************************************/

/*
 * si470x_get_report - receive a HID report
 */
static int si470x_get_report(struct si470x_device *radio, int size)
{
	return usb_control_msg(radio->usbdev,
		usb_rcvctrlpipe(radio->usbdev, 0),
		HID_REQ_GET_REPORT,
		USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN,
		radio->buf[0], 2,
		radio->buf, size, usb_timeout);
}


/*
 * si470x_set_report - send a HID report
 */
static int si470x_set_report(struct si470x_device *radio, int size)
{
	return usb_control_msg(radio->usbdev,
		usb_sndctrlpipe(radio->usbdev, 0),
		HID_REQ_SET_REPORT,
		USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
		radio->buf[0], 2,
		radio->buf, size, usb_timeout);
}


/*
 * si470x_get_register - read register
 */
static int si470x_get_register(struct si470x_device *radio, int regnr)
{
	int retval;

	radio->buf[0] = REGISTER_REPORT(regnr);

	retval = si470x_get_report(radio, REGISTER_REPORT_SIZE);
	if (retval >= 0)
		radio->registers[regnr] = (radio->buf[1] << 8) | radio->buf[2];

	return (retval < 0) ? -EINVAL : 0;
}


/*
 * si470x_set_register - write register
 */
static int si470x_set_register(struct si470x_device *radio, int regnr)
{
	int retval;

	radio->buf[0] = REGISTER_REPORT(regnr);
	radio->buf[1] = (radio->registers[regnr] & 0xff00) >> 8;
	radio->buf[2] = (radio->registers[regnr] & 0x00ff);

	retval = si470x_set_report(radio, REGISTER_REPORT_SIZE);

	return (retval < 0) ? -EINVAL : 0;
}


/*
 * si470x_get_all_registers - read entire registers
 */
static int si470x_get_all_registers(struct si470x_device *radio)
{
	int retval;
	int regnr;

	radio->buf[0] = ENTIRE_REPORT;

	retval = si470x_get_report(radio, ENTIRE_REPORT_SIZE);

	if (retval >= 0)
		for (regnr = 0; regnr < FMRADIO_REGISTER_NUM; regnr++)
			radio->registers[regnr] =
			(radio->buf[regnr * FMRADIO_REGISTER_SIZE + 1] << 8) |
			 radio->buf[regnr * FMRADIO_REGISTER_SIZE + 2];

	return (retval < 0) ? -EINVAL : 0;
}


/*
 * si470x_get_rds_registers - read rds registers
 */
static int si470x_get_rds_registers(struct si470x_device *radio)
{
	int retval;
	int regnr;
	int size;

	radio->buf[0] = RDS_REPORT;

	retval = usb_interrupt_msg(radio->usbdev,
		usb_rcvctrlpipe(radio->usbdev, 1),
		radio->buf, RDS_REPORT_SIZE, &size, usb_timeout);

	if (retval >= 0) {
		for (regnr = 0; regnr < RDS_REGISTER_NUM; regnr++) {
			radio->registers[STATUSRSSI + regnr] =
			(radio->buf[regnr * FMRADIO_REGISTER_SIZE + 1] << 8) |
			 radio->buf[regnr * FMRADIO_REGISTER_SIZE + 2];
		}
	}

	return (retval < 0) ? - EINVAL : 0;
}


/*
 * si470x_start - switch on radio
 */
static int si470x_start(struct si470x_device *radio)
{
	int retval;

	/* powercfg */
	radio->registers[POWERCFG] =
		POWERCFG_DMUTE | POWERCFG_ENABLE | POWERCFG_RDSM;
	retval = si470x_set_register(radio, POWERCFG);
	if (retval < 0)
		return retval;

	/* sysconfig 1 */
	radio->registers[SYSCONFIG1] =
		SYSCONFIG1_DE | SYSCONFIG1_RDS;
	retval = si470x_set_register(radio, SYSCONFIG1);
	if (retval < 0)
		return retval;

	/* sysconfig 2 */
	radio->registers[SYSCONFIG2] =
		(0x3f  << 8) |	/* SEEKTH */
		(band  << 6) |	/* BAND */
		(space << 4) |	/* SPACE */
		15;		/* VOLUME (max) */
	retval = si470x_set_register(radio, SYSCONFIG2);
	if (retval < 0)
		return retval;

	/* reset last channel */
	return si470x_set_chan(radio,
		radio->registers[CHANNEL] & CHANNEL_CHAN);
}


/*
 * si470x_stop - switch off radio
 */
static int si470x_stop(struct si470x_device *radio)
{
	/* powercfg */
	radio->registers[POWERCFG] &= ~POWERCFG_DMUTE;
	/* POWERCFG_ENABLE has to automatically go low */
	radio->registers[POWERCFG] |= POWERCFG_ENABLE |	POWERCFG_DISABLE;
	return si470x_set_register(radio, POWERCFG);
}


/*
 * si470x_set_chan - set the channel
 */
static int si470x_set_chan(struct si470x_device *radio, int chan)
{
	int retval, i;

	/* start tuning */
	radio->registers[CHANNEL] &= ~CHANNEL_CHAN;
	radio->registers[CHANNEL] |= CHANNEL_TUNE | chan;
	retval = si470x_set_register(radio, CHANNEL);
	if (retval < 0)
		return retval;

	/* wait till seek operation has completed */
	i = 0;
	do {
		retval = si470x_get_register(radio, STATUSRSSI);
		if (retval < 0)
			return retval;
	} while ((radio->registers[STATUSRSSI] & STATUSRSSI_STC) &&
		(++i < seek_retries));
	if (i >= seek_retries)
		printk(KERN_WARNING DRIVER_NAME
			": seek does not finish after %d tries\n", i);

	/* stop tuning */
	radio->registers[CHANNEL] &= ~CHANNEL_TUNE;
	return si470x_set_register(radio, CHANNEL);
}


/*
 * si470x_get_freq - get the frequency
 */
static int si470x_get_freq(struct si470x_device *radio)
{
	int spacing, band_bottom, chan, freq;
	int retval;

	/* Spacing (kHz) */
	switch (space) {
		/* 0: 200 kHz (USA, Australia) */
		default: spacing = 0.200 * FREQ_MUL; break;
		/* 1: 100 kHz (Europe, Japan) */
		case 1 : spacing = 0.100 * FREQ_MUL; break;
		/* 2:  50 kHz */
		case 2 : spacing = 0.050 * FREQ_MUL; break;
	};

	/* Bottom of Band (MHz) */
	switch (band) {
		/* 0: 87.5 - 108 MHz (USA, Europe) */
		default: band_bottom = 87.5 * FREQ_MUL; break;
		/* 1: 76   - 108 MHz (Japan wide band) */
		case 1 : band_bottom = 76   * FREQ_MUL; break;
		/* 2: 76   -  90 MHz (Japan) */
		case 2 : band_bottom = 76   * FREQ_MUL; break;
	};

	/* read channel */
	retval = si470x_get_register(radio, READCHAN);
	if (retval < 0)
		return retval;
	chan = radio->registers[READCHAN] & READCHAN_READCHAN;

	/* Frequency (MHz) = Spacing (kHz) x Channel + Bottom of Band (MHz) */
	freq = chan * spacing + band_bottom;

	return freq;
}


/*
 * si470x_set_freq - set the frequency
 */
static int si470x_set_freq(struct si470x_device *radio, int freq)
{
	int spacing, band_bottom, chan;

	/* Spacing (kHz) */
	switch (space) {
		/* 0: 200 kHz (USA, Australia) */
		default: spacing = 0.200 * FREQ_MUL; break;
		/* 1: 100 kHz (Europe, Japan) */
		case 1 : spacing = 0.100 * FREQ_MUL; break;
		/* 2:  50 kHz */
		case 2 : spacing = 0.050 * FREQ_MUL; break;
	};

	/* Bottom of Band (MHz) */
	switch (band) {
		/* 0: 87.5 - 108 MHz (USA, Europe) */
		default: band_bottom = 87.5 * FREQ_MUL; break;
		/* 1: 76   - 108 MHz (Japan wide band) */
		case 1 : band_bottom = 76   * FREQ_MUL; break;
		/* 2: 76   -  90 MHz (Japan) */
		case 2 : band_bottom = 76   * FREQ_MUL; break;
	};

	/* Chan = [ Freq (Mhz) - Bottom of Band (MHz) ] / Spacing (kHz) */
	chan = (freq - band_bottom) / spacing;

	return si470x_set_chan(radio, chan);
}



/*
 * si470x_rds - rds processing function
 */
static void si470x_rds(struct si470x_device *radio)
{
	unsigned long flags;
	unsigned char tmpbuf[3];
	unsigned char blocknum;
	unsigned char bler; /* RDS block errors */
	unsigned short rds;
	unsigned int i;

	if (radio->users == 0)
		return;
	if (si470x_get_rds_registers(radio) < 0)
		return;
	if ((radio->registers[STATUSRSSI] & STATUSRSSI_RDSR) == 0) {
		/* No RDS group ready */
		return;
	}
	if ((radio->registers[STATUSRSSI] & STATUSRSSI_RDSS) == 0) {
		/* RDS decoder not synchronized */
		return;
	}

	for (blocknum = 0; blocknum < 4; blocknum++) {
		switch (blocknum) {
			default:
				bler = (radio->registers[STATUSRSSI] &
						STATUSRSSI_BLERA) >> 9;
				rds = radio->registers[RDSA];
				break;
			case 1:
				bler = (radio->registers[READCHAN] &
						READCHAN_BLERB) >> 14;
				rds = radio->registers[RDSB];
				break;
			case 2:
				bler = (radio->registers[READCHAN] &
						READCHAN_BLERC) >> 12;
				rds = radio->registers[RDSC];
				break;
			case 3:
				bler = (radio->registers[READCHAN] &
						READCHAN_BLERD) >> 10;
				rds = radio->registers[RDSD];
				break;
		};

		/* Fill the V4L2 RDS buffer */
		tmpbuf[0] = rds & 0x00ff;	/* LSB */
		tmpbuf[1] = (rds & 0xff00) >> 8;/* MSB */
		tmpbuf[2] = blocknum;		/* offset name */
		tmpbuf[2] |= blocknum << 3;	/* received offset */
		if (bler > max_rds_errors)
			tmpbuf[2] |= 0x80;	/* uncorrectable errors */
		else if (bler > 0)
			tmpbuf[2] |= 0x40;	/* corrected error(s) */

		spin_lock_irqsave(&radio->lock, flags);

		/* copy RDS block to internal buffer */
		for (i = 0; i < 3; i++) {
			radio->buffer[radio->wr_index] = tmpbuf[i];
			radio->wr_index++;
		}

		if (radio->wr_index >= radio->buf_size)
			radio->wr_index = 0;

		if (radio->wr_index == radio->rd_index) {
			radio->rd_index += 3;
			if (radio->rd_index >= radio->buf_size)
				radio->rd_index = 0;
		} else
			radio->block_count++;

		spin_unlock_irqrestore(&radio->lock, flags);
	}

	radio->data_available_for_read = 1;
	wake_up_interruptible(&radio->read_queue);
}


/*
 * si470x_timer - rds timer function
 */
static void si470x_timer(unsigned long data)
{
	struct si470x_device *radio = (struct si470x_device *) data;

	schedule_work(&radio->work);
}


/*
 * si470x_timer - rds work function
 */
static void si470x_work(struct work_struct *work)
{
	struct si470x_device *radio = container_of(work, struct si470x_device,
		work);

	if (radio->users == 0)
		return;

	si470x_rds(radio);
	mod_timer(&radio->timer, jiffies + msecs_to_jiffies(rds_poll_time));
}



/**************************************************************************
 * USB interface functions
 **************************************************************************/

/*
 * si470x_usb_driver_probe - probe for the device
 */
static int si470x_usb_driver_probe(struct usb_interface *intf,
		const struct usb_device_id *id)
{
	struct si470x_device *radio;

	if (!(radio = kmalloc(sizeof(struct si470x_device), GFP_KERNEL)))
		return -ENOMEM;
	if (!(radio->videodev = video_device_alloc())) {
		kfree(radio);
		return -ENOMEM;
	}
	memcpy(radio->videodev, &si470x_viddev_template,
			sizeof(si470x_viddev_template));
	radio->users = 0;
	radio->usbdev = interface_to_usbdev(intf);
	video_set_drvdata(radio->videodev, radio);
	if (video_register_device(radio->videodev, VFL_TYPE_RADIO, radio_nr)) {
		printk(KERN_WARNING DRIVER_NAME
				": Could not register video device\n");
		video_device_release(radio->videodev);
		kfree(radio);
		return -EIO;
	}
	usb_set_intfdata(intf, radio);

	/* show some infos about the specific device */
	if (si470x_get_all_registers(radio) < 0) {
		video_device_release(radio->videodev);
		kfree(radio);
		return -EIO;
	}
	printk(KERN_INFO DRIVER_NAME ": DeviceID=0x%4.4x ChipID=0x%4.4x\n",
			radio->registers[DEVICEID], radio->registers[CHIPID]);

	/* check if firmware is current */
	if ((radio->registers[CHIPID] & CHIPID_FIRMWARE)
			< FMRADIO_SW_VERSION_CURRENT) {
		printk(KERN_WARNING DRIVER_NAME
			": This driver is known to work with chip version %d, "
			"but the device has firmware %d. If you have some "
			"trouble using this driver, please report to V4L ML "
			"at video4linux-list@redhat.com\n",
			radio->registers[CHIPID] & CHIPID_FIRMWARE,
			FMRADIO_SW_VERSION_CURRENT);
	}

	/* set initial frequency */
	si470x_set_freq(radio, 87.5 * FREQ_MUL); /* available in all regions */

	/* rds initialization */
	radio->buf_size = rds_buf * 3;
	if (NULL == (radio->buffer = kmalloc(radio->buf_size, GFP_KERNEL))) {
		video_device_release(radio->videodev);
		kfree(radio);
		return -ENOMEM;
	}
	radio->block_count = 0;
	radio->wr_index = 0;
	radio->rd_index = 0;
	radio->last_blocknum = 0xff;
	init_waitqueue_head(&radio->read_queue);
	radio->data_available_for_read = 0;

	/* prepare polling via eventd */
	INIT_WORK(&radio->work, si470x_work);
	init_timer(&radio->timer);
	radio->timer.function = si470x_timer;
	radio->timer.data = (unsigned long) radio;

	return 0;
}


/*
 * si470x_usb_driver_disconnect - disconnect the device
 */
static void si470x_usb_driver_disconnect(struct usb_interface *intf)
{
	struct si470x_device *radio = usb_get_intfdata(intf);

	del_timer_sync(&radio->timer);
	flush_scheduled_work();

	usb_set_intfdata(intf, NULL);
	if (radio) {
		video_unregister_device(radio->videodev);
		kfree(radio->buffer);
		kfree(radio);
	}
}



/**************************************************************************
 * Video4Linux interface functions
 **************************************************************************/

/*
 * si470x_fops_read - read RDS data
 */
static ssize_t si470x_fops_read(struct file *file, char __user *buf,
		size_t count, loff_t *ppos)
{
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));
	struct rds_command cmd;
	unsigned long flags;
	unsigned int i;
	unsigned int rd_blocks;

	cmd.block_count = count / 3; /* each RDS block needs 3 bytes */
	cmd.result = 0;
	cmd.buffer = buf;
	cmd.instance = file;

	/* copy RDS block out of internal buffer */
	while (!radio->data_available_for_read) {
		if (wait_event_interruptible(radio->read_queue,
				     radio->data_available_for_read) < 0)
			return -EINTR;
	}

	spin_lock_irqsave(&radio->lock, flags);
	rd_blocks = cmd.block_count;
	if (rd_blocks > radio->block_count)
		rd_blocks = radio->block_count;

	if (!rd_blocks) {
		spin_unlock_irqrestore(&radio->lock, flags);
		return cmd.result;
	}

	for (i = 0; i < rd_blocks; i++) {
		/* copy RDS block to user buffer */
		if (radio->rd_index == radio->wr_index)
			break;

		if (copy_to_user(buf, &radio->buffer[radio->rd_index], 3))
			break;

		radio->rd_index += 3;
		if (radio->rd_index >= radio->buf_size)
			radio->rd_index = 0;
		radio->block_count--;

		buf += 3;
		cmd.result += 3;
	}
	radio->data_available_for_read = (radio->block_count > 0);
	spin_unlock_irqrestore(&radio->lock, flags);

	return cmd.result;
}


/*
 * si470x_fops_poll - poll RDS data
 */
static unsigned int si470x_fops_poll(struct file *file,
		struct poll_table_struct *pts)
{
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));
	int retval;

	retval = 0;
	if (radio->data_available_for_read)
		retval = POLLIN | POLLRDNORM;
	poll_wait(file, &radio->read_queue, pts);

	return retval;
}


/*
 * si470x_fops_open - file open
 */
static int si470x_fops_open(struct inode *inode, struct file *file)
{
	int retval;
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));

	radio->users++;
	if (radio->users == 1) {
		retval = si470x_start(radio);
		if (retval < 0)
			return retval;

		schedule_work(&radio->work);
	}

	return 0;
}


/*
 * si470x_fops_release - file release
 */
static int si470x_fops_release(struct inode *inode, struct file *file)
{
	int retval;
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));

	if (!radio)
		return -ENODEV;

	radio->users--;
	if (radio->users == 0) {
		radio->data_available_for_read = 1;		/* ? */
		wake_up_interruptible(&radio->read_queue);	/* ? */

		retval = si470x_stop(radio);
		if (retval < 0)
			return retval;
	}

	return 0;
}


/*
 * si470x_vidioc_querycap - query device capabilities
 */
static int si470x_vidioc_querycap(struct file *file, void *priv,
		struct v4l2_capability *capability)
{
	strlcpy(capability->driver, DRIVER_NAME, sizeof(capability->driver));
	strlcpy(capability->card, DRIVER_CARD, sizeof(capability->card));
	sprintf(capability->bus_info, "USB");
	capability->version = DRIVER_VERSION;
	capability->capabilities = V4L2_CAP_TUNER | V4L2_CAP_RADIO;

	return 0;
}


/*
 * si470x_vidioc_g_input - get input
 */
static int si470x_vidioc_g_input(struct file *filp, void *priv,
		unsigned int *i)
{
	*i = 0;

	return 0;
}


/*
 * si470x_vidioc_s_input - set input
 */
static int si470x_vidioc_s_input(struct file *filp, void *priv, unsigned int i)
{
	if (i != 0)
		return -EINVAL;

	return 0;
}


/*
 * si470x_vidioc_queryctrl - enumerate control items
 */
static int si470x_vidioc_queryctrl(struct file *file, void *priv,
		struct v4l2_queryctrl *qc)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(radio_queryctrl); i++) {
		if (qc->id && qc->id == radio_queryctrl[i].id) {
			memcpy(qc, &(radio_queryctrl[i]), sizeof(*qc));
			return 0;
		}
	}

	return -EINVAL;
}


/*
 * si470x_vidioc_g_ctrl - get the value of a control
 */
static int si470x_vidioc_g_ctrl(struct file *file, void *priv,
		struct v4l2_control *ctrl)
{
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));

	switch (ctrl->id) {
		case V4L2_CID_AUDIO_VOLUME:
			ctrl->value = radio->registers[SYSCONFIG2] &
					SYSCONFIG2_VOLUME;
			break;
		case V4L2_CID_AUDIO_MUTE:
			ctrl->value = ((radio->registers[POWERCFG] &
					POWERCFG_DMUTE) == 0) ? 1 : 0;
			break;
	}

	return 0;
}


/*
 * si470x_vidioc_s_ctrl - set the value of a control
 */
static int si470x_vidioc_s_ctrl(struct file *file, void *priv,
		struct v4l2_control *ctrl)
{
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));

	switch (ctrl->id) {
		case V4L2_CID_AUDIO_VOLUME:
			radio->registers[SYSCONFIG2] &= ~SYSCONFIG2_VOLUME;
			radio->registers[SYSCONFIG2] |= ctrl->value;
			return si470x_set_register(radio, SYSCONFIG2);
		case V4L2_CID_AUDIO_MUTE:
			if (ctrl->value == 1)
				radio->registers[POWERCFG] &= ~POWERCFG_DMUTE;
			else
				radio->registers[POWERCFG] |= POWERCFG_DMUTE;
			return si470x_set_register(radio, POWERCFG);
	}

	return -EINVAL;
}


/*
 * si470x_vidioc_g_audio - get audio attributes
 */
static int si470x_vidioc_g_audio(struct file *file, void *priv,
		struct v4l2_audio *audio)
{
	if (audio->index > 1)
		return -EINVAL;

	strcpy(audio->name, "Radio");
	audio->capability = V4L2_AUDCAP_STEREO;

	return 0;
}


/*
 * si470x_vidioc_s_audio - set audio attributes
 */
static int si470x_vidioc_s_audio(struct file *file, void *priv,
		struct v4l2_audio *audio)
{
	if (audio->index != 0)
		return -EINVAL;

	return 0;
}


/*
 * si470x_vidioc_g_tuner - get tuner attributes
 */
static int si470x_vidioc_g_tuner(struct file *file, void *priv,
		struct v4l2_tuner *tuner)
{
	int retval;
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));

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

	/* read status rssi */
	retval = si470x_get_register(radio, STATUSRSSI);
	if (retval < 0)
		return retval;

	strcpy(tuner->name, "FM");
	tuner->type = V4L2_TUNER_RADIO;
	switch(band) {
		/* 0: 87.5 - 108 MHz (USA, Europe, default) */
		default:
			tuner->rangelow  =  87.5 * FREQ_MUL;
			tuner->rangehigh = 108   * FREQ_MUL;
			break;
		/* 1: 76   - 108 MHz (Japan wide band) */
		case 1 :
			tuner->rangelow  =  76   * FREQ_MUL;
			tuner->rangehigh = 108   * FREQ_MUL;
			break;
		/* 2: 76   -  90 MHz (Japan) */
		case 2 :
			tuner->rangelow  =  76   * FREQ_MUL;
			tuner->rangehigh =  90   * FREQ_MUL;
			break;
	};
	tuner->rxsubchans = V4L2_TUNER_SUB_MONO | V4L2_TUNER_SUB_STEREO;
	tuner->capability = V4L2_TUNER_CAP_LOW;

	/* Stereo indicator == Stereo (instead of Mono) */
	if ((radio->registers[STATUSRSSI] & STATUSRSSI_ST) == 1)
		tuner->audmode = V4L2_TUNER_MODE_STEREO;
	else
		tuner->audmode = V4L2_TUNER_MODE_MONO;

	/* min is worst, max is best; signal:0..0xffff; rssi: 0..0xff */
	tuner->signal = (radio->registers[STATUSRSSI] & STATUSRSSI_RSSI)
				* 0x0101;

	/* automatic frequency control: -1: freq to low, 1 freq to high */
	tuner->afc = 0;

	return 0;
}


/*
 * si470x_vidioc_s_tuner - set tuner attributes
 */
static int si470x_vidioc_s_tuner(struct file *file, void *priv,
		struct v4l2_tuner *tuner)
{
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));

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

	if (tuner->audmode == V4L2_TUNER_MODE_MONO)
		radio->registers[POWERCFG] |= POWERCFG_MONO;  /* force mono */
	else
		radio->registers[POWERCFG] &= ~POWERCFG_MONO; /* try stereo */

	return si470x_set_register(radio, POWERCFG);
}


/*
 * si470x_vidioc_g_frequency - get tuner or modulator radio frequency
 */
static int si470x_vidioc_g_frequency(struct file *file, void *priv,
		struct v4l2_frequency *freq)
{
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));

	freq->type = V4L2_TUNER_RADIO;
	freq->frequency = si470x_get_freq(radio);

	return 0;
}


/*
 * si470x_vidioc_s_frequency - set tuner or modulator radio frequency
 */
static int si470x_vidioc_s_frequency(struct file *file, void *priv,
		struct v4l2_frequency *freq)
{
	struct si470x_device *radio = video_get_drvdata(video_devdata(file));

	if (freq->type != V4L2_TUNER_RADIO)
		return -EINVAL;

	return si470x_set_freq(radio, freq->frequency);
}



/**************************************************************************
 * Module interface definitions and functions
 **************************************************************************/

/*
 * si470x_module_init - module init
 */
static int __init si470x_module_init(void)
{
	printk(KERN_INFO DRIVER_DESC "\n");
	return usb_register(&si470x_usb_driver);
}


/*
 * si470x_module_exit - module exit
 */
static void __exit si470x_module_exit(void)
{
	usb_deregister(&si470x_usb_driver);
}


module_init(si470x_module_init);
module_exit(si470x_module_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_VERSION("1.0.2");