aboutsummaryrefslogtreecommitdiffstats
path: root/openbsc/src/libbsc/system_information.c
blob: a3deefc73fe0b084daf2c9dbced2c2c41b779fb7 (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
/* GSM 04.08 System Information (SI) encoding and decoding
 * 3GPP TS 04.08 version 7.21.0 Release 1998 / ETSI TS 100 940 V7.21.0 */

/* (C) 2008-2010 by Harald Welte <laforge@gnumonks.org>
 * (C) 2012 Holger Hans Peter Freyther
 *
 * All Rights Reserved
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <netinet/in.h>

#include <osmocom/core/bitvec.h>
#include <osmocom/core/utils.h>
#include <osmocom/gsm/sysinfo.h>

#include <openbsc/debug.h>
#include <openbsc/gsm_04_08.h>
#include <openbsc/gsm_data.h>
#include <openbsc/abis_rsl.h>
#include <openbsc/rest_octets.h>
#include <openbsc/arfcn_range_encode.h>

/*
 * DCS1800 and PCS1900 have overlapping ARFCNs. We would need to set the
 * ARFCN_PCS flag on the 1900 ARFCNs but this would increase cell_alloc
 * and other arrays to make sure (ARFCN_PCS + 1024)/8 ARFCNs fit into the
 * array. DCS1800 and PCS1900 can not be used at the same time so conserve
 * memory and do the below.
 */
static int band_compatible(const struct gsm_bts *bts, int arfcn)
{
	enum gsm_band band = gsm_arfcn2band(arfcn);

	/* normal case */
	if (band == bts->band)
		return 1;
	/* deal with ARFCN_PCS not set */
	if (band == GSM_BAND_1800 && bts->band == GSM_BAND_1900)
		return 1;

	return 0;
}

static int is_dcs_net(const struct gsm_bts *bts)
{
	if (bts->band == GSM_BAND_850)
		return 0;
	if (bts->band == GSM_BAND_1900)
		return 0;
	return 1;
}

static int use_arfcn(const struct gsm_bts *bts, const int bis, const int ter,
			const int pgsm, const int arfcn)
{
	if (bts->force_combined_si)
		return !bis && !ter;
	if (!bis && !ter && band_compatible(bts, arfcn))
		return 1;
	/* Correct but somehow broken with either the nanoBTS or the iPhone5 */
	if (bis && pgsm && band_compatible(bts, arfcn) && (arfcn < 1 || arfcn > 124))
		return 1;
	if (ter && !band_compatible(bts, arfcn))
		return 1;
	return 0;
}

/* Frequency Lists as per TS 04.08 10.5.2.13 */

/* 10.5.2.13.2: Bit map 0 format */
static int freq_list_bm0_set_arfcn(uint8_t *chan_list, unsigned int arfcn)
{
	unsigned int byte, bit;

	if (arfcn > 124 || arfcn < 1) {
		LOGP(DRR, LOGL_ERROR, "Bitmap 0 only supports ARFCN 1...124\n");
		return -EINVAL;
	}

	/* the bitmask is from 1..124, not from 0..123 */
	arfcn--;

	byte = arfcn / 8;
	bit = arfcn % 8;

	chan_list[GSM48_CELL_CHAN_DESC_SIZE-1-byte] |= (1 << bit);

	return 0;
}

/* 10.5.2.13.7: Variable bit map format */
static int freq_list_bmrel_set_arfcn(uint8_t *chan_list, unsigned int arfcn)
{
	unsigned int byte, bit;
	unsigned int min_arfcn;
	unsigned int bitno;

	min_arfcn = (chan_list[0] & 1) << 9;
	min_arfcn |= chan_list[1] << 1;
	min_arfcn |= (chan_list[2] >> 7) & 1;

	/* The lower end of our bitmaks is always implicitly included */
	if (arfcn == min_arfcn)
		return 0;

	if (((arfcn - min_arfcn) & 1023) > 111) {
		LOGP(DRR, LOGL_ERROR, "arfcn(%u) > min(%u) + 111\n", arfcn, min_arfcn);
		return -EINVAL;
	}

	bitno = (arfcn - min_arfcn) & 1023;
	byte = bitno / 8;
	bit = bitno % 8;

	chan_list[2 + byte] |= 1 << (7 - bit);

	return 0;
}

/* generate a variable bitmap */
static int enc_freq_lst_var_bitmap(uint8_t *chan_list,
				struct bitvec *bv, const struct gsm_bts *bts,
				int bis, int ter, int min, int pgsm)
{
	int i;

	/* set it to 'Variable bitmap format' */
	chan_list[0] = 0x8e;

	chan_list[0] |= (min >> 9) & 1;
	chan_list[1] = (min >> 1);
	chan_list[2] = (min & 1) << 7;

	for (i = 0; i < bv->data_len*8; i++) {
		/* see notes in bitvec2freq_list */
		if (bitvec_get_bit_pos(bv, i)
		 && ((!bis && !ter && gsm_arfcn2band(i) == bts->band)
		  || (bis && pgsm && gsm_arfcn2band(i) == bts->band && (i < 1 || i > 124))
		  || (ter && gsm_arfcn2band(i) != bts->band))) {
			int rc = freq_list_bmrel_set_arfcn(chan_list, i);
			if (rc < 0)
				return rc;
		}
	}

	return 0;
}

/* generate a frequency list with the range 512 format */
static int enc_freq_lst_range(uint8_t *chan_list,
				struct bitvec *bv, const struct gsm_bts *bts,
				int bis, int ter, int pgsm)
{
	int arfcns[RANGE_ENC_MAX_ARFCNS];
	int w[RANGE_ENC_MAX_ARFCNS];
	int f0_included = 0;
	int arfcns_used = 0;
	int i, rc, range, f0;

	/*
	 * Select ARFCNs according to the rules in bitvec2freq_list
	 */
	for (i = 0; i < bv->data_len * 8; ++i) {
		/* More ARFCNs than the maximum */
		if (arfcns_used > ARRAY_SIZE(arfcns))
			return -1;
		/* Check if we can select it? */
		if (bitvec_get_bit_pos(bv, i) && use_arfcn(bts, bis, ter, pgsm, i))
			arfcns[arfcns_used++] = i;
	}

	/*
	 * Check if the given list of ARFCNs can be encoded.
	 */
	range = range_enc_determine_range(arfcns, arfcns_used, &f0);
	if (range == ARFCN_RANGE_INVALID)
		return -2;

	/*
	 * Manipulate the ARFCN list according to the rules in J4 depending
	 * on the selected range.
	 */
	arfcns_used = range_enc_filter_arfcns(arfcns, arfcns_used,
				f0, &f0_included);

	memset(w, 0, sizeof(w));
	rc = range_enc_arfcns(range, arfcns, arfcns_used, w, 0);
	if (rc != 0)
		return -3;

	/* Select the range and the amount of bits needed */
	switch (range) {
	case ARFCN_RANGE_128:
		return range_enc_range128(chan_list, f0, w);
		break;
	case ARFCN_RANGE_256:
		return range_enc_range256(chan_list, f0, w);
		break;
	case ARFCN_RANGE_512:
		return range_enc_range512(chan_list, f0, w);
		break;
	case ARFCN_RANGE_1024:
		return range_enc_range1024(chan_list, f0, f0_included, w);
		break;
	default:
		return -4;
	};
}

/* generate a cell channel list as per Section 10.5.2.1b of 04.08 */
static int bitvec2freq_list(uint8_t *chan_list, struct bitvec *bv,
			    const struct gsm_bts *bts, int bis, int ter)
{
	int i, rc, min = -1, max = -1, pgsm = 0, arfcns = 0;

	memset(chan_list, 0, 16);

	if (bts->band == GSM_BAND_900
	 && bts->c0->arfcn >= 1 && bts->c0->arfcn <= 124)
		pgsm = 1;
	/* P-GSM-only handsets only support 'bit map 0 format' */
	if (!bis && !ter && pgsm) {
		chan_list[0] = 0;

		for (i = 0; i < bv->data_len*8; i++) {
			if (i >= 1 && i <= 124
			 && bitvec_get_bit_pos(bv, i)) {
				rc = freq_list_bm0_set_arfcn(chan_list, i);
				if (rc < 0)
					return rc;
			}
		}
		return 0;
	}

	for (i = 0; i < bv->data_len*8; i++) {
		/* in case of SI2 or SI5 allow all neighbours in same band
		 * in case of SI*bis, allow neighbours in same band ouside pgsm
		 * in case of SI*ter, allow neighbours in different bands
		 */
		if (!bitvec_get_bit_pos(bv, i))
			continue;
		if (!use_arfcn(bts, bis, ter, pgsm, i))
			continue;
		/* count the arfcns we want to carry */
		arfcns += 1;

		/* 955..1023 < 0..885 */
		if (min < 0)
			min = i;
		if (i >= 955 && min < 955)
			min = i;
		if (i >= 955 && min >= 955 && i < min)
			min = i;
		if (i < 955 && min < 955 && i < min)
			min = i;
		if (max < 0)
			max = i;
		if (i < 955 && max >= 955)
			max = i;
		if (i >= 955 && max >= 955 && i > max)
			max = i;
		if (i < 955 && max < 955 && i > max)
			max = i;
	}

	if (max == -1) {
		/* Empty set, use 'bit map 0 format' */
		chan_list[0] = 0;
		return 0;
	}

	/* Now find the best encoding */
	if (((max - min) & 1023) <= 111)
		return enc_freq_lst_var_bitmap(chan_list, bv, bts, bis,
				ter, min, pgsm);

	/* Attempt to do the range encoding */
	rc = enc_freq_lst_range(chan_list, bv, bts, bis, ter, pgsm);
	if (rc == 0)
		return 0;

	LOGP(DRR, LOGL_ERROR, "min_arfcn=%u, max_arfcn=%u, arfcns=%d "
		"can not generate ARFCN list", min, max, arfcns);
	return -EINVAL;
}

/* generate a cell channel list as per Section 10.5.2.1b of 04.08 */
/* static*/ int generate_cell_chan_list(uint8_t *chan_list, struct gsm_bts *bts)
{
	struct gsm_bts_trx *trx;
	struct bitvec *bv = &bts->si_common.cell_alloc;

	/* Zero-initialize the bit-vector */
	memset(bv->data, 0, bv->data_len);

	/* first we generate a bitvec of all TRX ARFCN's in our BTS */
	llist_for_each_entry(trx, &bts->trx_list, list) {
		unsigned int i, j;
		/* Always add the TRX's ARFCN */
		bitvec_set_bit_pos(bv, trx->arfcn, 1);
		for (i = 0; i < ARRAY_SIZE(trx->ts); i++) {
			struct gsm_bts_trx_ts *ts = &trx->ts[i];
			/* Add any ARFCNs present in hopping channels */
			for (j = 0; j < 1024; j++) {
				if (bitvec_get_bit_pos(&ts->hopping.arfcns, j))
					bitvec_set_bit_pos(bv, j, 1);
			}
		}
	}

	/* then we generate a GSM 04.08 frequency list from the bitvec */
	return bitvec2freq_list(chan_list, bv, bts, 0, 0);
}

/* generate a cell channel list as per Section 10.5.2.1b of 04.08 */
static int generate_bcch_chan_list(uint8_t *chan_list, struct gsm_bts *bts,
	int si5, int bis, int ter)
{
	struct gsm_bts *cur_bts;
	struct bitvec *bv;

	if (si5 && bts->neigh_list_manual_mode == NL_MODE_MANUAL_SI5SEP)
		bv = &bts->si_common.si5_neigh_list;
	else
		bv = &bts->si_common.neigh_list;

	/* Generate list of neighbor cells if we are in automatic mode */
	if (bts->neigh_list_manual_mode == NL_MODE_AUTOMATIC) {
		/* Zero-initialize the bit-vector */
		memset(bv->data, 0, bv->data_len);

		/* first we generate a bitvec of the BCCH ARFCN's in our BSC */
		llist_for_each_entry(cur_bts, &bts->network->bts_list, list) {
			if (cur_bts == bts)
				continue;
			bitvec_set_bit_pos(bv, cur_bts->c0->arfcn, 1);
		}
	}

	/* then we generate a GSM 04.08 frequency list from the bitvec */
	return bitvec2freq_list(chan_list, bv, bts, bis, ter);
}

static int list_arfcn(uint8_t *chan_list, uint8_t mask, char *text)
{
	int n = 0, i;
	struct gsm_sysinfo_freq freq[1024];

	memset(freq, 0, sizeof(freq));
	gsm48_decode_freq_list(freq, chan_list, 16, 0xce, 1);
	for (i = 0; i < 1024; i++) {
		if (freq[i].mask) {
			if (!n)
				LOGP(DRR, LOGL_INFO, "%s", text);
			LOGPC(DRR, LOGL_INFO, " %d", i);
			n++;
		}
	}
	if (n)
		LOGPC(DRR, LOGL_INFO, "\n");

	return n;
}

static int generate_si1(uint8_t *output, struct gsm_bts *bts)
{
	int rc;
	struct gsm48_system_information_type_1 *si1 =
		(struct gsm48_system_information_type_1 *) output;

	memset(si1, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	si1->header.l2_plen = (21 << 2) | 1;
	si1->header.rr_protocol_discriminator = GSM48_PDISC_RR;
	si1->header.skip_indicator = 0;
	si1->header.system_information = GSM48_MT_RR_SYSINFO_1;

	rc = generate_cell_chan_list(si1->cell_channel_description, bts);
	if (rc < 0)
		return rc;
	list_arfcn(si1->cell_channel_description, 0xce, "Serving cell:");

	si1->rach_control = bts->si_common.rach_control;

	/*
	 * SI1 Rest Octets (10.5.2.32), contains NCH position and band
	 * indicator but that is not in the 04.08.
	 */
	rc = rest_octets_si1(si1->rest_octets, NULL, is_dcs_net(bts));

	return sizeof(*si1) + rc;
}

static int generate_si2(uint8_t *output, struct gsm_bts *bts)
{
	int rc;
	struct gsm48_system_information_type_2 *si2 =
		(struct gsm48_system_information_type_2 *) output;

	memset(si2, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	si2->header.l2_plen = (22 << 2) | 1;
	si2->header.rr_protocol_discriminator = GSM48_PDISC_RR;
	si2->header.skip_indicator = 0;
	si2->header.system_information = GSM48_MT_RR_SYSINFO_2;

	rc = generate_bcch_chan_list(si2->bcch_frequency_list, bts, 0, 0, 0);
	if (rc < 0)
		return rc;
	list_arfcn(si2->bcch_frequency_list, 0xce,
		"Neighbour cells in same band:");

	si2->ncc_permitted = bts->si_common.ncc_permitted;
	si2->rach_control = bts->si_common.rach_control;

	return sizeof(*si2);
}

static int generate_si2bis(uint8_t *output, struct gsm_bts *bts)
{
	int rc;
	struct gsm48_system_information_type_2bis *si2b =
		(struct gsm48_system_information_type_2bis *) output;
	int n;

	memset(si2b, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	si2b->header.l2_plen = (22 << 2) | 1;
	si2b->header.rr_protocol_discriminator = GSM48_PDISC_RR;
	si2b->header.skip_indicator = 0;
	si2b->header.system_information = GSM48_MT_RR_SYSINFO_2bis;

	rc = generate_bcch_chan_list(si2b->bcch_frequency_list, bts, 0, 1, 0);
	if (rc < 0)
		return rc;
	n = list_arfcn(si2b->bcch_frequency_list, 0xce,
		"Neighbour cells in same band, but outside P-GSM:");
	if (n) {
		/* indicate in SI2 and SI2bis: there is an extension */
		struct gsm48_system_information_type_2 *si2 =
			(struct gsm48_system_information_type_2 *)
				bts->si_buf[SYSINFO_TYPE_2];
		si2->bcch_frequency_list[0] |= 0x20;
		si2b->bcch_frequency_list[0] |= 0x20;
	} else
		bts->si_valid &= ~(1 << SYSINFO_TYPE_2bis);

	si2b->rach_control = bts->si_common.rach_control;

	return sizeof(*si2b);
}

static int generate_si2ter(uint8_t *output, struct gsm_bts *bts)
{
	int rc;
	struct gsm48_system_information_type_2ter *si2t =
		(struct gsm48_system_information_type_2ter *) output;
	int n;

	memset(si2t, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	si2t->header.l2_plen = (22 << 2) | 1;
	si2t->header.rr_protocol_discriminator = GSM48_PDISC_RR;
	si2t->header.skip_indicator = 0;
	si2t->header.system_information = GSM48_MT_RR_SYSINFO_2ter;

	rc = generate_bcch_chan_list(si2t->ext_bcch_frequency_list, bts, 0, 0, 1);
	if (rc < 0)
		return rc;
	n = list_arfcn(si2t->ext_bcch_frequency_list, 0x8e,
		"Neighbour cells in different band:");
	if (!n)
		bts->si_valid &= ~(1 << SYSINFO_TYPE_2ter);

	return sizeof(*si2t);
}

static struct gsm48_si_ro_info si_info = {
	.selection_params = {
		.present = 0,
	},
	.power_offset = {
		.present = 0,
	},
	.si2ter_indicator = 0,
	.early_cm_ctrl = 1,
	.scheduling = {
		.present = 0,
	},
	.gprs_ind = {
		.si13_position = 0,
		.ra_colour = 0,
		.present = 1,
	},
	.lsa_params = {
		.present = 0,
	},
	.cell_id = 0,	/* FIXME: doesn't the bts have this? */
	.break_ind = 0,
};

static int generate_si3(uint8_t *output, struct gsm_bts *bts)
{
	int rc;
	struct gsm48_system_information_type_3 *si3 =
		(struct gsm48_system_information_type_3 *) output;

	memset(si3, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	si3->header.l2_plen = (18 << 2) | 1;
	si3->header.rr_protocol_discriminator = GSM48_PDISC_RR;
	si3->header.skip_indicator = 0;
	si3->header.system_information = GSM48_MT_RR_SYSINFO_3;

	si3->cell_identity = htons(bts->cell_identity);
	gsm48_generate_lai(&si3->lai, bts->network->country_code,
			   bts->network->network_code,
			   bts->location_area_code);
	si3->control_channel_desc = bts->si_common.chan_desc;
	si3->cell_options = bts->si_common.cell_options;
	si3->cell_sel_par = bts->si_common.cell_sel_par;
	si3->rach_control = bts->si_common.rach_control;

	if ((bts->si_valid & (1 << SYSINFO_TYPE_2ter))) {
		LOGP(DRR, LOGL_INFO, "SI 2ter is included.\n");
		si_info.si2ter_indicator = 1;
	} else {
		si_info.si2ter_indicator = 0;
	}

	/* SI3 Rest Octets (10.5.2.34), containing
		CBQ, CELL_RESELECT_OFFSET, TEMPORARY_OFFSET, PENALTY_TIME
		Power Offset, 2ter Indicator, Early Classmark Sending,
		Scheduling if and WHERE, GPRS Indicator, SI13 position */
	rc = rest_octets_si3(si3->rest_octets, &si_info);

	return sizeof(*si3) + rc;
}

static int generate_si4(uint8_t *output, struct gsm_bts *bts)
{
	int rc;
	struct gsm48_system_information_type_4 *si4 =
		(struct gsm48_system_information_type_4 *) output;

	/* length of all IEs present except SI4 rest octets and l2_plen */
	int l2_plen = sizeof(*si4) - 1;

	memset(si4, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	si4->header.rr_protocol_discriminator = GSM48_PDISC_RR;
	si4->header.skip_indicator = 0;
	si4->header.system_information = GSM48_MT_RR_SYSINFO_4;

	gsm48_generate_lai(&si4->lai, bts->network->country_code,
			   bts->network->network_code,
			   bts->location_area_code);
	si4->cell_sel_par = bts->si_common.cell_sel_par;
	si4->rach_control = bts->si_common.rach_control;

	/* Optional: CBCH Channel Description + CBCH Mobile Allocation */

	si4->header.l2_plen = (l2_plen << 2) | 1;

	/* SI4 Rest Octets (10.5.2.35), containing
		Optional Power offset, GPRS Indicator,
		Cell Identity, LSA ID, Selection Parameter */
	rc = rest_octets_si4(si4->data, &si_info);

	return sizeof(*si4) + rc;
}

static int generate_si5(uint8_t *output, struct gsm_bts *bts)
{
	struct gsm48_system_information_type_5 *si5;
	int rc, l2_plen = 18;

	memset(output, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	/* ip.access nanoBTS needs l2_plen!! */
	switch (bts->type) {
	case GSM_BTS_TYPE_NANOBTS:
	case GSM_BTS_TYPE_OSMO_SYSMO:
		*output++ = (l2_plen << 2) | 1;
		l2_plen++;
		break;
	default:
		break;
	}

	si5 = (struct gsm48_system_information_type_5 *) output;

	/* l2 pseudo length, not part of msg: 18 */
	si5->rr_protocol_discriminator = GSM48_PDISC_RR;
	si5->skip_indicator = 0;
	si5->system_information = GSM48_MT_RR_SYSINFO_5;
	rc = generate_bcch_chan_list(si5->bcch_frequency_list, bts, 1, 0, 0);
	if (rc < 0)
		return rc;
	list_arfcn(si5->bcch_frequency_list, 0xce,
		"Neighbour cells in same band:");

	/* 04.08 9.1.37: L2 Pseudo Length of 18 */
	return l2_plen;
}

static int generate_si5bis(uint8_t *output, struct gsm_bts *bts)
{
	struct gsm48_system_information_type_5bis *si5b;
	int rc, l2_plen = 18;
	int n;

	memset(output, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	/* ip.access nanoBTS needs l2_plen!! */
	switch (bts->type) {
	case GSM_BTS_TYPE_NANOBTS:
	case GSM_BTS_TYPE_OSMO_SYSMO:
		*output++ = (l2_plen << 2) | 1;
		l2_plen++;
		break;
	default:
		break;
	}

	si5b = (struct gsm48_system_information_type_5bis *) output;

	/* l2 pseudo length, not part of msg: 18 */
	si5b->rr_protocol_discriminator = GSM48_PDISC_RR;
	si5b->skip_indicator = 0;
	si5b->system_information = GSM48_MT_RR_SYSINFO_5bis;
	rc = generate_bcch_chan_list(si5b->bcch_frequency_list, bts, 1, 1, 0);
	if (rc < 0)
		return rc;
	n = list_arfcn(si5b->bcch_frequency_list, 0xce,
		"Neighbour cells in same band, but outside P-GSM:");
	if (n) {
		/* indicate in SI5 and SI5bis: there is an extension */
		struct gsm48_system_information_type_5 *si5 =
			(struct gsm48_system_information_type_5 *)
				bts->si_buf[SYSINFO_TYPE_5];
		si5->bcch_frequency_list[0] |= 0x20;
		si5b->bcch_frequency_list[0] |= 0x20;
	} else
		bts->si_valid &= ~(1 << SYSINFO_TYPE_5bis);

	/* 04.08 9.1.37: L2 Pseudo Length of 18 */
	return l2_plen;
}

static int generate_si5ter(uint8_t *output, struct gsm_bts *bts)
{
	struct gsm48_system_information_type_5ter *si5t;
	int rc, l2_plen = 18;
	int n;

	memset(output, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	/* ip.access nanoBTS needs l2_plen!! */
	switch (bts->type) {
	case GSM_BTS_TYPE_NANOBTS:
	case GSM_BTS_TYPE_OSMO_SYSMO:
		*output++ = (l2_plen << 2) | 1;
		l2_plen++;
		break;
	default:
		break;
	}

	si5t = (struct gsm48_system_information_type_5ter *) output;

	/* l2 pseudo length, not part of msg: 18 */
	si5t->rr_protocol_discriminator = GSM48_PDISC_RR;
	si5t->skip_indicator = 0;
	si5t->system_information = GSM48_MT_RR_SYSINFO_5ter;
	rc = generate_bcch_chan_list(si5t->bcch_frequency_list, bts, 1, 0, 1);
	if (rc < 0)
		return rc;
	n = list_arfcn(si5t->bcch_frequency_list, 0x8e,
		"Neighbour cells in different band:");
	if (!n)
		bts->si_valid &= ~(1 << SYSINFO_TYPE_5ter);

	/* 04.08 9.1.37: L2 Pseudo Length of 18 */
	return l2_plen;
}

static int generate_si6(uint8_t *output, struct gsm_bts *bts)
{
	struct gsm48_system_information_type_6 *si6;
	int l2_plen = 11;

	memset(output, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	/* ip.access nanoBTS needs l2_plen!! */
	switch (bts->type) {
	case GSM_BTS_TYPE_NANOBTS:
	case GSM_BTS_TYPE_OSMO_SYSMO:
		*output++ = (l2_plen << 2) | 1;
		l2_plen++;
		break;
	default:
		break;
	}

	si6 = (struct gsm48_system_information_type_6 *) output;

	/* l2 pseudo length, not part of msg: 11 */
	si6->rr_protocol_discriminator = GSM48_PDISC_RR;
	si6->skip_indicator = 0;
	si6->system_information = GSM48_MT_RR_SYSINFO_6;
	si6->cell_identity = htons(bts->cell_identity);
	gsm48_generate_lai(&si6->lai, bts->network->country_code,
			   bts->network->network_code,
			   bts->location_area_code);
	si6->cell_options = bts->si_common.cell_options;
	si6->ncc_permitted = bts->si_common.ncc_permitted;

	/* SI6 Rest Octets: 10.5.2.35a: PCH / NCH info, VBS/VGCS options */

	return l2_plen;
}

static struct gsm48_si13_info si13_default = {
	.cell_opts = {
		.nmo 		= GPRS_NMO_II,
		.t3168		= 2000,
		.t3192		= 1500,
		.drx_timer_max	= 3,
		.bs_cv_max	= 15,
		.ext_info_present = 0,
		.ext_info = {
			/* The values below are just guesses ! */
			.egprs_supported = 0,
			.use_egprs_p_ch_req = 1,
			.bep_period = 5,
			.pfc_supported = 0,
			.dtm_supported = 0,
			.bss_paging_coordination = 0,
		},
	},
	.pwr_ctrl_pars = {
		.alpha		= 0,	/* a = 0.0 */
		.t_avg_w	= 16,
		.t_avg_t	= 16,
		.pc_meas_chan	= 0, 	/* downling measured on CCCH */
		.n_avg_i	= 8,
	},
	.bcch_change_mark	= 1,
	.si_change_field	= 0,
	.pbcch_present		= 0,
	{
		.no_pbcch = {
			.rac		= 0,	/* needs to be patched */
			.spgc_ccch_sup 	= 0,
			.net_ctrl_ord	= 0,
			.prio_acc_thr	= 6,
		},
	},
};

static int generate_si13(uint8_t *output, struct gsm_bts *bts)
{
	struct gsm48_system_information_type_13 *si13 =
		(struct gsm48_system_information_type_13 *) output;
	int ret;

	memset(si13, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);

	si13->header.rr_protocol_discriminator = GSM48_PDISC_RR;
	si13->header.skip_indicator = 0;
	si13->header.system_information = GSM48_MT_RR_SYSINFO_13;

	si13_default.no_pbcch.rac = bts->gprs.rac;
	si13_default.no_pbcch.net_ctrl_ord = bts->gprs.net_ctrl_ord;

	ret = rest_octets_si13(si13->rest_octets, &si13_default);
	if (ret < 0)
		return ret;

	/* length is coded in bit 2 an up */
	si13->header.l2_plen = 0x01;

	return sizeof (*si13) + ret;
}

typedef int (*gen_si_fn_t)(uint8_t *output, struct gsm_bts *bts);

static const gen_si_fn_t gen_si_fn[_MAX_SYSINFO_TYPE] = {
	[SYSINFO_TYPE_1] = &generate_si1,
	[SYSINFO_TYPE_2] = &generate_si2,
	[SYSINFO_TYPE_2bis] = &generate_si2bis,
	[SYSINFO_TYPE_2ter] = &generate_si2ter,
	[SYSINFO_TYPE_3] = &generate_si3,
	[SYSINFO_TYPE_4] = &generate_si4,
	[SYSINFO_TYPE_5] = &generate_si5,
	[SYSINFO_TYPE_5bis] = &generate_si5bis,
	[SYSINFO_TYPE_5ter] = &generate_si5ter,
	[SYSINFO_TYPE_6] = &generate_si6,
	[SYSINFO_TYPE_13] = &generate_si13,
};

int gsm_generate_si(struct gsm_bts *bts, enum osmo_sysinfo_type si_type)
{
	gen_si_fn_t gen_si;

	switch (bts->gprs.mode) {
	case BTS_GPRS_EGPRS:
		si13_default.cell_opts.ext_info_present = 1;
		si13_default.cell_opts.ext_info.egprs_supported = 1;
		/* fallthrough */
	case BTS_GPRS_GPRS:
		si_info.gprs_ind.present = 1;
		break;
	case BTS_GPRS_NONE:
		si_info.gprs_ind.present = 0;
		break;
	}

	memcpy(&si_info.selection_params,
	       &bts->si_common.cell_ro_sel_par,
	       sizeof(struct gsm48_si_selection_params));

	gen_si = gen_si_fn[si_type];
	if (!gen_si)
		return -EINVAL;

	return gen_si(bts->si_buf[si_type], bts);
}