aboutsummaryrefslogtreecommitdiff
path: root/drivers/net/ieee802154/cc2520.c
blob: d50add705a79a19d42874e73cc1ec9fdfd40692f (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
/* Driver for TI CC2520 802.15.4 Wireless-PAN Networking controller
 *
 * Copyright (C) 2014 Varka Bhadram <varkab@cdac.in>
 *		      Md.Jamal Mohiuddin <mjmohiuddin@cdac.in>
 *		      P Sowjanya <sowjanyap@cdac.in>
 *
 * 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.
 *
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/gpio.h>
#include <linux/delay.h>
#include <linux/spi/spi.h>
#include <linux/spi/cc2520.h>
#include <linux/workqueue.h>
#include <linux/interrupt.h>
#include <linux/skbuff.h>
#include <linux/of_gpio.h>
#include <linux/ieee802154.h>
#include <linux/crc-ccitt.h>
#include <asm/unaligned.h>

#include <net/mac802154.h>
#include <net/cfg802154.h>

#define	SPI_COMMAND_BUFFER	3
#define	HIGH			1
#define	LOW			0
#define	STATE_IDLE		0
#define	RSSI_VALID		0
#define	RSSI_OFFSET		78

#define	CC2520_RAM_SIZE		640
#define	CC2520_FIFO_SIZE	128

#define	CC2520RAM_TXFIFO	0x100
#define	CC2520RAM_RXFIFO	0x180
#define	CC2520RAM_IEEEADDR	0x3EA
#define	CC2520RAM_PANID		0x3F2
#define	CC2520RAM_SHORTADDR	0x3F4

#define	CC2520_FREG_MASK	0x3F

/* status byte values */
#define	CC2520_STATUS_XOSC32M_STABLE	BIT(7)
#define	CC2520_STATUS_RSSI_VALID	BIT(6)
#define	CC2520_STATUS_TX_UNDERFLOW	BIT(3)

/* IEEE-802.15.4 defined constants (2.4 GHz logical channels) */
#define	CC2520_MINCHANNEL		11
#define	CC2520_MAXCHANNEL		26
#define	CC2520_CHANNEL_SPACING		5

/* command strobes */
#define	CC2520_CMD_SNOP			0x00
#define	CC2520_CMD_IBUFLD		0x02
#define	CC2520_CMD_SIBUFEX		0x03
#define	CC2520_CMD_SSAMPLECCA		0x04
#define	CC2520_CMD_SRES			0x0f
#define	CC2520_CMD_MEMORY_MASK		0x0f
#define	CC2520_CMD_MEMORY_READ		0x10
#define	CC2520_CMD_MEMORY_WRITE		0x20
#define	CC2520_CMD_RXBUF		0x30
#define	CC2520_CMD_RXBUFCP		0x38
#define	CC2520_CMD_RXBUFMOV		0x32
#define	CC2520_CMD_TXBUF		0x3A
#define	CC2520_CMD_TXBUFCP		0x3E
#define	CC2520_CMD_RANDOM		0x3C
#define	CC2520_CMD_SXOSCON		0x40
#define	CC2520_CMD_STXCAL		0x41
#define	CC2520_CMD_SRXON		0x42
#define	CC2520_CMD_STXON		0x43
#define	CC2520_CMD_STXONCCA		0x44
#define	CC2520_CMD_SRFOFF		0x45
#define	CC2520_CMD_SXOSCOFF		0x46
#define	CC2520_CMD_SFLUSHRX		0x47
#define	CC2520_CMD_SFLUSHTX		0x48
#define	CC2520_CMD_SACK			0x49
#define	CC2520_CMD_SACKPEND		0x4A
#define	CC2520_CMD_SNACK		0x4B
#define	CC2520_CMD_SRXMASKBITSET	0x4C
#define	CC2520_CMD_SRXMASKBITCLR	0x4D
#define	CC2520_CMD_RXMASKAND		0x4E
#define	CC2520_CMD_RXMASKOR		0x4F
#define	CC2520_CMD_MEMCP		0x50
#define	CC2520_CMD_MEMCPR		0x52
#define	CC2520_CMD_MEMXCP		0x54
#define	CC2520_CMD_MEMXWR		0x56
#define	CC2520_CMD_BCLR			0x58
#define	CC2520_CMD_BSET			0x59
#define	CC2520_CMD_CTR_UCTR		0x60
#define	CC2520_CMD_CBCMAC		0x64
#define	CC2520_CMD_UCBCMAC		0x66
#define	CC2520_CMD_CCM			0x68
#define	CC2520_CMD_UCCM			0x6A
#define	CC2520_CMD_ECB			0x70
#define	CC2520_CMD_ECBO			0x72
#define	CC2520_CMD_ECBX			0x74
#define	CC2520_CMD_INC			0x78
#define	CC2520_CMD_ABORT		0x7F
#define	CC2520_CMD_REGISTER_READ	0x80
#define	CC2520_CMD_REGISTER_WRITE	0xC0

/* status registers */
#define	CC2520_CHIPID			0x40
#define	CC2520_VERSION			0x42
#define	CC2520_EXTCLOCK			0x44
#define	CC2520_MDMCTRL0			0x46
#define	CC2520_MDMCTRL1			0x47
#define	CC2520_FREQEST			0x48
#define	CC2520_RXCTRL			0x4A
#define	CC2520_FSCTRL			0x4C
#define	CC2520_FSCAL0			0x4E
#define	CC2520_FSCAL1			0x4F
#define	CC2520_FSCAL2			0x50
#define	CC2520_FSCAL3			0x51
#define	CC2520_AGCCTRL0			0x52
#define	CC2520_AGCCTRL1			0x53
#define	CC2520_AGCCTRL2			0x54
#define	CC2520_AGCCTRL3			0x55
#define	CC2520_ADCTEST0			0x56
#define	CC2520_ADCTEST1			0x57
#define	CC2520_ADCTEST2			0x58
#define	CC2520_MDMTEST0			0x5A
#define	CC2520_MDMTEST1			0x5B
#define	CC2520_DACTEST0			0x5C
#define	CC2520_DACTEST1			0x5D
#define	CC2520_ATEST			0x5E
#define	CC2520_DACTEST2			0x5F
#define	CC2520_PTEST0			0x60
#define	CC2520_PTEST1			0x61
#define	CC2520_RESERVED			0x62
#define	CC2520_DPUBIST			0x7A
#define	CC2520_ACTBIST			0x7C
#define	CC2520_RAMBIST			0x7E

/* frame registers */
#define	CC2520_FRMFILT0			0x00
#define	CC2520_FRMFILT1			0x01
#define	CC2520_SRCMATCH			0x02
#define	CC2520_SRCSHORTEN0		0x04
#define	CC2520_SRCSHORTEN1		0x05
#define	CC2520_SRCSHORTEN2		0x06
#define	CC2520_SRCEXTEN0		0x08
#define	CC2520_SRCEXTEN1		0x09
#define	CC2520_SRCEXTEN2		0x0A
#define	CC2520_FRMCTRL0			0x0C
#define	CC2520_FRMCTRL1			0x0D
#define	CC2520_RXENABLE0		0x0E
#define	CC2520_RXENABLE1		0x0F
#define	CC2520_EXCFLAG0			0x10
#define	CC2520_EXCFLAG1			0x11
#define	CC2520_EXCFLAG2			0x12
#define	CC2520_EXCMASKA0		0x14
#define	CC2520_EXCMASKA1		0x15
#define	CC2520_EXCMASKA2		0x16
#define	CC2520_EXCMASKB0		0x18
#define	CC2520_EXCMASKB1		0x19
#define	CC2520_EXCMASKB2		0x1A
#define	CC2520_EXCBINDX0		0x1C
#define	CC2520_EXCBINDX1		0x1D
#define	CC2520_EXCBINDY0		0x1E
#define	CC2520_EXCBINDY1		0x1F
#define	CC2520_GPIOCTRL0		0x20
#define	CC2520_GPIOCTRL1		0x21
#define	CC2520_GPIOCTRL2		0x22
#define	CC2520_GPIOCTRL3		0x23
#define	CC2520_GPIOCTRL4		0x24
#define	CC2520_GPIOCTRL5		0x25
#define	CC2520_GPIOPOLARITY		0x26
#define	CC2520_GPIOCTRL			0x28
#define	CC2520_DPUCON			0x2A
#define	CC2520_DPUSTAT			0x2C
#define	CC2520_FREQCTRL			0x2E
#define	CC2520_FREQTUNE			0x2F
#define	CC2520_TXPOWER			0x30
#define	CC2520_TXCTRL			0x31
#define	CC2520_FSMSTAT0			0x32
#define	CC2520_FSMSTAT1			0x33
#define	CC2520_FIFOPCTRL		0x34
#define	CC2520_FSMCTRL			0x35
#define	CC2520_CCACTRL0			0x36
#define	CC2520_CCACTRL1			0x37
#define	CC2520_RSSI			0x38
#define	CC2520_RSSISTAT			0x39
#define	CC2520_RXFIRST			0x3C
#define	CC2520_RXFIFOCNT		0x3E
#define	CC2520_TXFIFOCNT		0x3F

/* CC2520_FRMFILT0 */
#define FRMFILT0_FRAME_FILTER_EN	BIT(0)
#define FRMFILT0_PAN_COORDINATOR	BIT(1)

/* CC2520_FRMCTRL0 */
#define FRMCTRL0_AUTOACK		BIT(5)
#define FRMCTRL0_AUTOCRC		BIT(6)

/* CC2520_FRMCTRL1 */
#define FRMCTRL1_SET_RXENMASK_ON_TX	BIT(0)
#define FRMCTRL1_IGNORE_TX_UNDERF	BIT(1)

/* Driver private information */
struct cc2520_private {
	struct spi_device *spi;		/* SPI device structure */
	struct ieee802154_hw *hw;	/* IEEE-802.15.4 device */
	u8 *buf;			/* SPI TX/Rx data buffer */
	struct mutex buffer_mutex;	/* SPI buffer mutex */
	bool is_tx;			/* Flag for sync b/w Tx and Rx */
	bool amplified;			/* Flag for CC2591 */
	int fifo_pin;			/* FIFO GPIO pin number */
	struct work_struct fifop_irqwork;/* Workqueue for FIFOP */
	spinlock_t lock;		/* Lock for is_tx*/
	struct completion tx_complete;	/* Work completion for Tx */
	bool promiscuous;               /* Flag for promiscuous mode */
};

/* Generic Functions */
static int
cc2520_cmd_strobe(struct cc2520_private *priv, u8 cmd)
{
	int ret;
	u8 status = 0xff;
	struct spi_message msg;
	struct spi_transfer xfer = {
		.len = 0,
		.tx_buf = priv->buf,
		.rx_buf = priv->buf,
	};

	spi_message_init(&msg);
	spi_message_add_tail(&xfer, &msg);

	mutex_lock(&priv->buffer_mutex);
	priv->buf[xfer.len++] = cmd;
	dev_vdbg(&priv->spi->dev,
		 "command strobe buf[0] = %02x\n",
		 priv->buf[0]);

	ret = spi_sync(priv->spi, &msg);
	if (!ret)
		status = priv->buf[0];
	dev_vdbg(&priv->spi->dev,
		 "buf[0] = %02x\n", priv->buf[0]);
	mutex_unlock(&priv->buffer_mutex);

	return ret;
}

static int
cc2520_get_status(struct cc2520_private *priv, u8 *status)
{
	int ret;
	struct spi_message msg;
	struct spi_transfer xfer = {
		.len = 0,
		.tx_buf = priv->buf,
		.rx_buf = priv->buf,
	};

	spi_message_init(&msg);
	spi_message_add_tail(&xfer, &msg);

	mutex_lock(&priv->buffer_mutex);
	priv->buf[xfer.len++] = CC2520_CMD_SNOP;
	dev_vdbg(&priv->spi->dev,
		 "get status command buf[0] = %02x\n", priv->buf[0]);

	ret = spi_sync(priv->spi, &msg);
	if (!ret)
		*status = priv->buf[0];
	dev_vdbg(&priv->spi->dev,
		 "buf[0] = %02x\n", priv->buf[0]);
	mutex_unlock(&priv->buffer_mutex);

	return ret;
}

static int
cc2520_write_register(struct cc2520_private *priv, u8 reg, u8 value)
{
	int status;
	struct spi_message msg;
	struct spi_transfer xfer = {
		.len = 0,
		.tx_buf = priv->buf,
		.rx_buf = priv->buf,
	};

	spi_message_init(&msg);
	spi_message_add_tail(&xfer, &msg);

	mutex_lock(&priv->buffer_mutex);

	if (reg <= CC2520_FREG_MASK) {
		priv->buf[xfer.len++] = CC2520_CMD_REGISTER_WRITE | reg;
		priv->buf[xfer.len++] = value;
	} else {
		priv->buf[xfer.len++] = CC2520_CMD_MEMORY_WRITE;
		priv->buf[xfer.len++] = reg;
		priv->buf[xfer.len++] = value;
	}
	status = spi_sync(priv->spi, &msg);
	if (msg.status)
		status = msg.status;

	mutex_unlock(&priv->buffer_mutex);

	return status;
}

static int
cc2520_write_ram(struct cc2520_private *priv, u16 reg, u8 len, u8 *data)
{
	int status;
	struct spi_message msg;
	struct spi_transfer xfer_head = {
		.len        = 0,
		.tx_buf        = priv->buf,
		.rx_buf        = priv->buf,
	};

	struct spi_transfer xfer_buf = {
		.len = len,
		.tx_buf = data,
	};

	mutex_lock(&priv->buffer_mutex);
	priv->buf[xfer_head.len++] = (CC2520_CMD_MEMORY_WRITE |
						((reg >> 8) & 0xff));
	priv->buf[xfer_head.len++] = reg & 0xff;

	spi_message_init(&msg);
	spi_message_add_tail(&xfer_head, &msg);
	spi_message_add_tail(&xfer_buf, &msg);

	status = spi_sync(priv->spi, &msg);
	dev_dbg(&priv->spi->dev, "spi status = %d\n", status);
	if (msg.status)
		status = msg.status;

	mutex_unlock(&priv->buffer_mutex);
	return status;
}

static int
cc2520_read_register(struct cc2520_private *priv, u8 reg, u8 *data)
{
	int status;
	struct spi_message msg;
	struct spi_transfer xfer1 = {
		.len = 0,
		.tx_buf = priv->buf,
		.rx_buf = priv->buf,
	};

	struct spi_transfer xfer2 = {
		.len = 1,
		.rx_buf = data,
	};

	spi_message_init(&msg);
	spi_message_add_tail(&xfer1, &msg);
	spi_message_add_tail(&xfer2, &msg);

	mutex_lock(&priv->buffer_mutex);
	priv->buf[xfer1.len++] = CC2520_CMD_MEMORY_READ;
	priv->buf[xfer1.len++] = reg;

	status = spi_sync(priv->spi, &msg);
	dev_dbg(&priv->spi->dev,
		"spi status = %d\n", status);
	if (msg.status)
		status = msg.status;

	mutex_unlock(&priv->buffer_mutex);

	return status;
}

static int
cc2520_write_txfifo(struct cc2520_private *priv, u8 pkt_len, u8 *data, u8 len)
{
	int status;

	/* length byte must include FCS even
	 * if it is calculated in the hardware
	 */
	int len_byte = pkt_len;

	struct spi_message msg;

	struct spi_transfer xfer_head = {
		.len = 0,
		.tx_buf = priv->buf,
		.rx_buf = priv->buf,
	};
	struct spi_transfer xfer_len = {
		.len = 1,
		.tx_buf = &len_byte,
	};
	struct spi_transfer xfer_buf = {
		.len = len,
		.tx_buf = data,
	};

	spi_message_init(&msg);
	spi_message_add_tail(&xfer_head, &msg);
	spi_message_add_tail(&xfer_len, &msg);
	spi_message_add_tail(&xfer_buf, &msg);

	mutex_lock(&priv->buffer_mutex);
	priv->buf[xfer_head.len++] = CC2520_CMD_TXBUF;
	dev_vdbg(&priv->spi->dev,
		 "TX_FIFO cmd buf[0] = %02x\n", priv->buf[0]);

	status = spi_sync(priv->spi, &msg);
	dev_vdbg(&priv->spi->dev, "status = %d\n", status);
	if (msg.status)
		status = msg.status;
	dev_vdbg(&priv->spi->dev, "status = %d\n", status);
	dev_vdbg(&priv->spi->dev, "buf[0] = %02x\n", priv->buf[0]);
	mutex_unlock(&priv->buffer_mutex);

	return status;
}

static int
cc2520_read_rxfifo(struct cc2520_private *priv, u8 *data, u8 len)
{
	int status;
	struct spi_message msg;

	struct spi_transfer xfer_head = {
		.len = 0,
		.tx_buf = priv->buf,
		.rx_buf = priv->buf,
	};
	struct spi_transfer xfer_buf = {
		.len = len,
		.rx_buf = data,
	};

	spi_message_init(&msg);
	spi_message_add_tail(&xfer_head, &msg);
	spi_message_add_tail(&xfer_buf, &msg);

	mutex_lock(&priv->buffer_mutex);
	priv->buf[xfer_head.len++] = CC2520_CMD_RXBUF;

	dev_vdbg(&priv->spi->dev, "read rxfifo buf[0] = %02x\n", priv->buf[0]);
	dev_vdbg(&priv->spi->dev, "buf[1] = %02x\n", priv->buf[1]);

	status = spi_sync(priv->spi, &msg);
	dev_vdbg(&priv->spi->dev, "status = %d\n", status);
	if (msg.status)
		status = msg.status;
	dev_vdbg(&priv->spi->dev, "status = %d\n", status);
	dev_vdbg(&priv->spi->dev,
		 "return status buf[0] = %02x\n", priv->buf[0]);
	dev_vdbg(&priv->spi->dev, "length buf[1] = %02x\n", priv->buf[1]);

	mutex_unlock(&priv->buffer_mutex);

	return status;
}

static int cc2520_start(struct ieee802154_hw *hw)
{
	return cc2520_cmd_strobe(hw->priv, CC2520_CMD_SRXON);
}

static void cc2520_stop(struct ieee802154_hw *hw)
{
	cc2520_cmd_strobe(hw->priv, CC2520_CMD_SRFOFF);
}

static int
cc2520_tx(struct ieee802154_hw *hw, struct sk_buff *skb)
{
	struct cc2520_private *priv = hw->priv;
	unsigned long flags;
	int rc;
	u8 status = 0;
	u8 pkt_len;

	/* In promiscuous mode we disable AUTOCRC so we can get the raw CRC
	 * values on RX. This means we need to manually add the CRC on TX.
	 */
	if (priv->promiscuous) {
		u16 crc = crc_ccitt(0, skb->data, skb->len);

		put_unaligned_le16(crc, skb_put(skb, 2));
		pkt_len = skb->len;
	} else {
		pkt_len = skb->len + 2;
	}

	rc = cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHTX);
	if (rc)
		goto err_tx;

	rc = cc2520_write_txfifo(priv, pkt_len, skb->data, skb->len);
	if (rc)
		goto err_tx;

	rc = cc2520_get_status(priv, &status);
	if (rc)
		goto err_tx;

	if (status & CC2520_STATUS_TX_UNDERFLOW) {
		dev_err(&priv->spi->dev, "cc2520 tx underflow exception\n");
		goto err_tx;
	}

	spin_lock_irqsave(&priv->lock, flags);
	BUG_ON(priv->is_tx);
	priv->is_tx = 1;
	spin_unlock_irqrestore(&priv->lock, flags);

	rc = cc2520_cmd_strobe(priv, CC2520_CMD_STXONCCA);
	if (rc)
		goto err;

	rc = wait_for_completion_interruptible(&priv->tx_complete);
	if (rc < 0)
		goto err;

	cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHTX);
	cc2520_cmd_strobe(priv, CC2520_CMD_SRXON);

	return rc;
err:
	spin_lock_irqsave(&priv->lock, flags);
	priv->is_tx = 0;
	spin_unlock_irqrestore(&priv->lock, flags);
err_tx:
	return rc;
}

static int cc2520_rx(struct cc2520_private *priv)
{
	u8 len = 0, lqi = 0, bytes = 1;
	struct sk_buff *skb;

	/* Read single length byte from the radio. */
	cc2520_read_rxfifo(priv, &len, bytes);

	if (!ieee802154_is_valid_psdu_len(len)) {
		/* Corrupted frame received, clear frame buffer by
		 * reading entire buffer.
		 */
		dev_dbg(&priv->spi->dev, "corrupted frame received\n");
		len = IEEE802154_MTU;
	}

	skb = dev_alloc_skb(len);
	if (!skb)
		return -ENOMEM;

	if (cc2520_read_rxfifo(priv, skb_put(skb, len), len)) {
		dev_dbg(&priv->spi->dev, "frame reception failed\n");
		kfree_skb(skb);
		return -EINVAL;
	}

	/* In promiscuous mode, we configure the radio to include the
	 * CRC (AUTOCRC==0) and we pass on the packet unconditionally. If not
	 * in promiscuous mode, we check the CRC here, but leave the
	 * RSSI/LQI/CRC_OK bytes as they will get removed in the mac layer.
	 */
	if (!priv->promiscuous) {
		bool crc_ok;

		/* Check if the CRC is valid. With AUTOCRC set, the most
		 * significant bit of the last byte returned from the CC2520
		 * is CRC_OK flag. See section 20.3.4 of the datasheet.
		 */
		crc_ok = skb->data[len - 1] & BIT(7);

		/* If we failed CRC drop the packet in the driver layer. */
		if (!crc_ok) {
			dev_dbg(&priv->spi->dev, "CRC check failed\n");
			kfree_skb(skb);
			return -EINVAL;
		}

		/* To calculate LQI, the lower 7 bits of the last byte (the
		 * correlation value provided by the radio) must be scaled to
		 * the range 0-255. According to section 20.6, the correlation
		 * value ranges from 50-110. Ideally this would be calibrated
		 * per hardware design, but we use roughly the datasheet values
		 * to get close enough while avoiding floating point.
		 */
		lqi = skb->data[len - 1] & 0x7f;
		if (lqi < 50)
			lqi = 50;
		else if (lqi > 113)
			lqi = 113;
		lqi = (lqi - 50) * 4;
	}

	ieee802154_rx_irqsafe(priv->hw, skb, lqi);

	dev_vdbg(&priv->spi->dev, "RXFIFO: %x %x\n", len, lqi);

	return 0;
}

static int
cc2520_ed(struct ieee802154_hw *hw, u8 *level)
{
	struct cc2520_private *priv = hw->priv;
	u8 status = 0xff;
	u8 rssi;
	int ret;

	ret = cc2520_read_register(priv, CC2520_RSSISTAT, &status);
	if (ret)
		return ret;

	if (status != RSSI_VALID)
		return -EINVAL;

	ret = cc2520_read_register(priv, CC2520_RSSI, &rssi);
	if (ret)
		return ret;

	/* level = RSSI(rssi) - OFFSET [dBm] : offset is 76dBm */
	*level = rssi - RSSI_OFFSET;

	return 0;
}

static int
cc2520_set_channel(struct ieee802154_hw *hw, u8 page, u8 channel)
{
	struct cc2520_private *priv = hw->priv;
	int ret;

	dev_dbg(&priv->spi->dev, "trying to set channel\n");

	BUG_ON(page != 0);
	BUG_ON(channel < CC2520_MINCHANNEL);
	BUG_ON(channel > CC2520_MAXCHANNEL);

	ret = cc2520_write_register(priv, CC2520_FREQCTRL,
				    11 + 5*(channel - 11));

	return ret;
}

static int
cc2520_filter(struct ieee802154_hw *hw,
	      struct ieee802154_hw_addr_filt *filt, unsigned long changed)
{
	struct cc2520_private *priv = hw->priv;
	int ret = 0;

	if (changed & IEEE802154_AFILT_PANID_CHANGED) {
		u16 panid = le16_to_cpu(filt->pan_id);

		dev_vdbg(&priv->spi->dev,
			 "cc2520_filter called for pan id\n");
		ret = cc2520_write_ram(priv, CC2520RAM_PANID,
				       sizeof(panid), (u8 *)&panid);
	}

	if (changed & IEEE802154_AFILT_IEEEADDR_CHANGED) {
		dev_vdbg(&priv->spi->dev,
			 "cc2520_filter called for IEEE addr\n");
		ret = cc2520_write_ram(priv, CC2520RAM_IEEEADDR,
				       sizeof(filt->ieee_addr),
				       (u8 *)&filt->ieee_addr);
	}

	if (changed & IEEE802154_AFILT_SADDR_CHANGED) {
		u16 addr = le16_to_cpu(filt->short_addr);

		dev_vdbg(&priv->spi->dev,
			 "cc2520_filter called for saddr\n");
		ret = cc2520_write_ram(priv, CC2520RAM_SHORTADDR,
				       sizeof(addr), (u8 *)&addr);
	}

	if (changed & IEEE802154_AFILT_PANC_CHANGED) {
		u8 frmfilt0;

		dev_vdbg(&priv->spi->dev,
			 "cc2520_filter called for panc change\n");

		cc2520_read_register(priv, CC2520_FRMFILT0, &frmfilt0);

		if (filt->pan_coord)
			frmfilt0 |= FRMFILT0_PAN_COORDINATOR;
		else
			frmfilt0 &= ~FRMFILT0_PAN_COORDINATOR;

		ret = cc2520_write_register(priv, CC2520_FRMFILT0, frmfilt0);
	}

	return ret;
}

static inline int cc2520_set_tx_power(struct cc2520_private *priv, s32 mbm)
{
	u8 power;

	switch (mbm) {
	case 500:
		power = 0xF7;
		break;
	case 300:
		power = 0xF2;
		break;
	case 200:
		power = 0xAB;
		break;
	case 100:
		power = 0x13;
		break;
	case 0:
		power = 0x32;
		break;
	case -200:
		power = 0x81;
		break;
	case -400:
		power = 0x88;
		break;
	case -700:
		power = 0x2C;
		break;
	case -1800:
		power = 0x03;
		break;
	default:
		return -EINVAL;
	}

	return cc2520_write_register(priv, CC2520_TXPOWER, power);
}

static inline int cc2520_cc2591_set_tx_power(struct cc2520_private *priv,
					     s32 mbm)
{
	u8 power;

	switch (mbm) {
	case 1700:
		power = 0xF9;
		break;
	case 1600:
		power = 0xF0;
		break;
	case 1400:
		power = 0xA0;
		break;
	case 1100:
		power = 0x2C;
		break;
	case -100:
		power = 0x03;
		break;
	case -800:
		power = 0x01;
		break;
	default:
		return -EINVAL;
	}

	return cc2520_write_register(priv, CC2520_TXPOWER, power);
}

#define CC2520_MAX_TX_POWERS 0x8
static const s32 cc2520_powers[CC2520_MAX_TX_POWERS + 1] = {
	500, 300, 200, 100, 0, -200, -400, -700, -1800,
};

#define CC2520_CC2591_MAX_TX_POWERS 0x5
static const s32 cc2520_cc2591_powers[CC2520_CC2591_MAX_TX_POWERS + 1] = {
	1700, 1600, 1400, 1100, -100, -800,
};

static int
cc2520_set_txpower(struct ieee802154_hw *hw, s32 mbm)
{
	struct cc2520_private *priv = hw->priv;

	if (!priv->amplified)
		return cc2520_set_tx_power(priv, mbm);

	return cc2520_cc2591_set_tx_power(priv, mbm);
}

static int
cc2520_set_promiscuous_mode(struct ieee802154_hw *hw, bool on)
{
	struct cc2520_private *priv = hw->priv;
	u8 frmfilt0;

	dev_dbg(&priv->spi->dev, "%s : mode %d\n", __func__, on);

	priv->promiscuous = on;

	cc2520_read_register(priv, CC2520_FRMFILT0, &frmfilt0);

	if (on) {
		/* Disable automatic ACK, automatic CRC, and frame filtering. */
		cc2520_write_register(priv, CC2520_FRMCTRL0, 0);
		frmfilt0 &= ~FRMFILT0_FRAME_FILTER_EN;
	} else {
		cc2520_write_register(priv, CC2520_FRMCTRL0, FRMCTRL0_AUTOACK |
							     FRMCTRL0_AUTOCRC);
		frmfilt0 |= FRMFILT0_FRAME_FILTER_EN;
	}
	return cc2520_write_register(priv, CC2520_FRMFILT0, frmfilt0);
}

static const struct ieee802154_ops cc2520_ops = {
	.owner = THIS_MODULE,
	.start = cc2520_start,
	.stop = cc2520_stop,
	.xmit_sync = cc2520_tx,
	.ed = cc2520_ed,
	.set_channel = cc2520_set_channel,
	.set_hw_addr_filt = cc2520_filter,
	.set_txpower = cc2520_set_txpower,
	.set_promiscuous_mode = cc2520_set_promiscuous_mode,
};

static int cc2520_register(struct cc2520_private *priv)
{
	int ret = -ENOMEM;

	priv->hw = ieee802154_alloc_hw(sizeof(*priv), &cc2520_ops);
	if (!priv->hw)
		goto err_ret;

	priv->hw->priv = priv;
	priv->hw->parent = &priv->spi->dev;
	priv->hw->extra_tx_headroom = 0;
	ieee802154_random_extended_addr(&priv->hw->phy->perm_extended_addr);

	/* We do support only 2.4 Ghz */
	priv->hw->phy->supported.channels[0] = 0x7FFF800;
	priv->hw->flags = IEEE802154_HW_TX_OMIT_CKSUM | IEEE802154_HW_AFILT |
			  IEEE802154_HW_PROMISCUOUS;

	priv->hw->phy->flags = WPAN_PHY_FLAG_TXPOWER;

	if (!priv->amplified) {
		priv->hw->phy->supported.tx_powers = cc2520_powers;
		priv->hw->phy->supported.tx_powers_size = ARRAY_SIZE(cc2520_powers);
		priv->hw->phy->transmit_power = priv->hw->phy->supported.tx_powers[4];
	} else {
		priv->hw->phy->supported.tx_powers = cc2520_cc2591_powers;
		priv->hw->phy->supported.tx_powers_size = ARRAY_SIZE(cc2520_cc2591_powers);
		priv->hw->phy->transmit_power = priv->hw->phy->supported.tx_powers[0];
	}

	priv->hw->phy->current_channel = 11;

	dev_vdbg(&priv->spi->dev, "registered cc2520\n");
	ret = ieee802154_register_hw(priv->hw);
	if (ret)
		goto err_free_device;

	return 0;

err_free_device:
	ieee802154_free_hw(priv->hw);
err_ret:
	return ret;
}

static void cc2520_fifop_irqwork(struct work_struct *work)
{
	struct cc2520_private *priv
		= container_of(work, struct cc2520_private, fifop_irqwork);

	dev_dbg(&priv->spi->dev, "fifop interrupt received\n");

	if (gpio_get_value(priv->fifo_pin))
		cc2520_rx(priv);
	else
		dev_dbg(&priv->spi->dev, "rxfifo overflow\n");

	cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHRX);
	cc2520_cmd_strobe(priv, CC2520_CMD_SFLUSHRX);
}

static irqreturn_t cc2520_fifop_isr(int irq, void *data)
{
	struct cc2520_private *priv = data;

	schedule_work(&priv->fifop_irqwork);

	return IRQ_HANDLED;
}

static irqreturn_t cc2520_sfd_isr(int irq, void *data)
{
	struct cc2520_private *priv = data;
	unsigned long flags;

	spin_lock_irqsave(&priv->lock, flags);
	if (priv->is_tx) {
		priv->is_tx = 0;
		spin_unlock_irqrestore(&priv->lock, flags);
		dev_dbg(&priv->spi->dev, "SFD for TX\n");
		complete(&priv->tx_complete);
	} else {
		spin_unlock_irqrestore(&priv->lock, flags);
		dev_dbg(&priv->spi->dev, "SFD for RX\n");
	}

	return IRQ_HANDLED;
}

static int cc2520_get_platform_data(struct spi_device *spi,
				    struct cc2520_platform_data *pdata)
{
	struct device_node *np = spi->dev.of_node;
	struct cc2520_private *priv = spi_get_drvdata(spi);

	if (!np) {
		struct cc2520_platform_data *spi_pdata = spi->dev.platform_data;
		if (!spi_pdata)
			return -ENOENT;
		*pdata = *spi_pdata;
		priv->fifo_pin = pdata->fifo;
		return 0;
	}

	pdata->fifo = of_get_named_gpio(np, "fifo-gpio", 0);
	priv->fifo_pin = pdata->fifo;

	pdata->fifop = of_get_named_gpio(np, "fifop-gpio", 0);

	pdata->sfd = of_get_named_gpio(np, "sfd-gpio", 0);
	pdata->cca = of_get_named_gpio(np, "cca-gpio", 0);
	pdata->vreg = of_get_named_gpio(np, "vreg-gpio", 0);
	pdata->reset = of_get_named_gpio(np, "reset-gpio", 0);

	/* CC2591 front end for CC2520 */
	if (of_property_read_bool(np, "amplified"))
		priv->amplified = true;

	return 0;
}

static int cc2520_hw_init(struct cc2520_private *priv)
{
	u8 status = 0, state = 0xff;
	int ret;
	int timeout = 100;
	struct cc2520_platform_data pdata;

	ret = cc2520_get_platform_data(priv->spi, &pdata);
	if (ret)
		goto err_ret;

	ret = cc2520_read_register(priv, CC2520_FSMSTAT1, &state);
	if (ret)
		goto err_ret;

	if (state != STATE_IDLE)
		return -EINVAL;

	do {
		ret = cc2520_get_status(priv, &status);
		if (ret)
			goto err_ret;

		if (timeout-- <= 0) {
			dev_err(&priv->spi->dev, "oscillator start failed!\n");
			return ret;
		}
		udelay(1);
	} while (!(status & CC2520_STATUS_XOSC32M_STABLE));

	dev_vdbg(&priv->spi->dev, "oscillator brought up\n");

	/* If the CC2520 is connected to a CC2591 amplifier, we must both
	 * configure GPIOs on the CC2520 to correctly configure the CC2591
	 * and change a couple settings of the CC2520 to work with the
	 * amplifier. See section 8 page 17 of TI application note AN065.
	 * http://www.ti.com/lit/an/swra229a/swra229a.pdf
	 */
	if (priv->amplified) {
		ret = cc2520_write_register(priv, CC2520_AGCCTRL1, 0x16);
		if (ret)
			goto err_ret;

		ret = cc2520_write_register(priv, CC2520_GPIOCTRL0, 0x46);
		if (ret)
			goto err_ret;

		ret = cc2520_write_register(priv, CC2520_GPIOCTRL5, 0x47);
		if (ret)
			goto err_ret;

		ret = cc2520_write_register(priv, CC2520_GPIOPOLARITY, 0x1e);
		if (ret)
			goto err_ret;

		ret = cc2520_write_register(priv, CC2520_TXCTRL, 0xc1);
		if (ret)
			goto err_ret;
	} else {
		ret = cc2520_write_register(priv, CC2520_AGCCTRL1, 0x11);
		if (ret)
			goto err_ret;
	}

	/* Registers default value: section 28.1 in Datasheet */

	/* Set the CCA threshold to -50 dBm. This seems to have been copied
	 * from the TinyOS CC2520 driver and is much higher than the -84 dBm
	 * threshold suggested in the datasheet.
	 */
	ret = cc2520_write_register(priv, CC2520_CCACTRL0, 0x1A);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_MDMCTRL0, 0x85);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_MDMCTRL1, 0x14);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_RXCTRL, 0x3f);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_FSCTRL, 0x5a);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_FSCAL1, 0x2b);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_ADCTEST0, 0x10);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_ADCTEST1, 0x0e);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_ADCTEST2, 0x03);
	if (ret)
		goto err_ret;

	/* Configure registers correctly for this driver. */
	ret = cc2520_write_register(priv, CC2520_FRMCTRL1,
				    FRMCTRL1_SET_RXENMASK_ON_TX |
				    FRMCTRL1_IGNORE_TX_UNDERF);
	if (ret)
		goto err_ret;

	ret = cc2520_write_register(priv, CC2520_FIFOPCTRL, 127);
	if (ret)
		goto err_ret;

	return 0;

err_ret:
	return ret;
}

static int cc2520_probe(struct spi_device *spi)
{
	struct cc2520_private *priv;
	struct cc2520_platform_data pdata;
	int ret;

	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	spi_set_drvdata(spi, priv);

	ret = cc2520_get_platform_data(spi, &pdata);
	if (ret < 0) {
		dev_err(&spi->dev, "no platform data\n");
		return -EINVAL;
	}

	priv->spi = spi;

	priv->buf = devm_kzalloc(&spi->dev,
				 SPI_COMMAND_BUFFER, GFP_KERNEL);
	if (!priv->buf)
		return -ENOMEM;

	mutex_init(&priv->buffer_mutex);
	INIT_WORK(&priv->fifop_irqwork, cc2520_fifop_irqwork);
	spin_lock_init(&priv->lock);
	init_completion(&priv->tx_complete);

	/* Assumption that CC2591 is not connected */
	priv->amplified = false;

	/* Request all the gpio's */
	if (!gpio_is_valid(pdata.fifo)) {
		dev_err(&spi->dev, "fifo gpio is not valid\n");
		ret = -EINVAL;
		goto err_hw_init;
	}

	ret = devm_gpio_request_one(&spi->dev, pdata.fifo,
				    GPIOF_IN, "fifo");
	if (ret)
		goto err_hw_init;

	if (!gpio_is_valid(pdata.cca)) {
		dev_err(&spi->dev, "cca gpio is not valid\n");
		ret = -EINVAL;
		goto err_hw_init;
	}

	ret = devm_gpio_request_one(&spi->dev, pdata.cca,
				    GPIOF_IN, "cca");
	if (ret)
		goto err_hw_init;

	if (!gpio_is_valid(pdata.fifop)) {
		dev_err(&spi->dev, "fifop gpio is not valid\n");
		ret = -EINVAL;
		goto err_hw_init;
	}

	ret = devm_gpio_request_one(&spi->dev, pdata.fifop,
				    GPIOF_IN, "fifop");
	if (ret)
		goto err_hw_init;

	if (!gpio_is_valid(pdata.sfd)) {
		dev_err(&spi->dev, "sfd gpio is not valid\n");
		ret = -EINVAL;
		goto err_hw_init;
	}

	ret = devm_gpio_request_one(&spi->dev, pdata.sfd,
				    GPIOF_IN, "sfd");
	if (ret)
		goto err_hw_init;

	if (!gpio_is_valid(pdata.reset)) {
		dev_err(&spi->dev, "reset gpio is not valid\n");
		ret = -EINVAL;
		goto err_hw_init;
	}

	ret = devm_gpio_request_one(&spi->dev, pdata.reset,
				    GPIOF_OUT_INIT_LOW, "reset");
	if (ret)
		goto err_hw_init;

	if (!gpio_is_valid(pdata.vreg)) {
		dev_err(&spi->dev, "vreg gpio is not valid\n");
		ret = -EINVAL;
		goto err_hw_init;
	}

	ret = devm_gpio_request_one(&spi->dev, pdata.vreg,
				    GPIOF_OUT_INIT_LOW, "vreg");
	if (ret)
		goto err_hw_init;

	gpio_set_value(pdata.vreg, HIGH);
	usleep_range(100, 150);

	gpio_set_value(pdata.reset, HIGH);
	usleep_range(200, 250);

	ret = cc2520_hw_init(priv);
	if (ret)
		goto err_hw_init;

	/* Set up fifop interrupt */
	ret = devm_request_irq(&spi->dev,
			       gpio_to_irq(pdata.fifop),
			       cc2520_fifop_isr,
			       IRQF_TRIGGER_RISING,
			       dev_name(&spi->dev),
			       priv);
	if (ret) {
		dev_err(&spi->dev, "could not get fifop irq\n");
		goto err_hw_init;
	}

	/* Set up sfd interrupt */
	ret = devm_request_irq(&spi->dev,
			       gpio_to_irq(pdata.sfd),
			       cc2520_sfd_isr,
			       IRQF_TRIGGER_FALLING,
			       dev_name(&spi->dev),
			       priv);
	if (ret) {
		dev_err(&spi->dev, "could not get sfd irq\n");
		goto err_hw_init;
	}

	ret = cc2520_register(priv);
	if (ret)
		goto err_hw_init;

	return 0;

err_hw_init:
	mutex_destroy(&priv->buffer_mutex);
	flush_work(&priv->fifop_irqwork);
	return ret;
}

static int cc2520_remove(struct spi_device *spi)
{
	struct cc2520_private *priv = spi_get_drvdata(spi);

	mutex_destroy(&priv->buffer_mutex);
	flush_work(&priv->fifop_irqwork);

	ieee802154_unregister_hw(priv->hw);
	ieee802154_free_hw(priv->hw);

	return 0;
}

static const struct spi_device_id cc2520_ids[] = {
	{"cc2520", },
	{},
};
MODULE_DEVICE_TABLE(spi, cc2520_ids);

static const struct of_device_id cc2520_of_ids[] = {
	{.compatible = "ti,cc2520", },
	{},
};
MODULE_DEVICE_TABLE(of, cc2520_of_ids);

/* SPI driver structure */
static struct spi_driver cc2520_driver = {
	.driver = {
		.name = "cc2520",
		.of_match_table = of_match_ptr(cc2520_of_ids),
	},
	.id_table = cc2520_ids,
	.probe = cc2520_probe,
	.remove = cc2520_remove,
};
module_spi_driver(cc2520_driver);

MODULE_AUTHOR("Varka Bhadram <varkab@cdac.in>");
MODULE_DESCRIPTION("CC2520 Transceiver Driver");
MODULE_LICENSE("GPL v2");