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/* L1 SAP primitives */

/* (C) 2011 by Harald Welte <laforge@gnumonks.org>
 * (C) 2013 by Andreas Eversberg <jolly@eversberg.eu>
 *
 * 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 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 <stdint.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <inttypes.h>

#include <osmocom/core/msgb.h>
#include <osmocom/gsm/l1sap.h>
#include <osmocom/gsm/gsm_utils.h>
#include <osmocom/gsm/rsl.h>
#include <osmocom/core/gsmtap.h>
#include <osmocom/core/gsmtap_util.h>
#include <osmocom/core/utils.h>

#include <osmocom/trau/osmo_ortp.h>

#include <osmo-bts/logging.h>
#include <osmo-bts/gsm_data.h>
#include <osmo-bts/l1sap.h>
#include <osmo-bts/dtx_dl_amr_fsm.h>
#include <osmo-bts/pcu_if.h>
#include <osmo-bts/measurement.h>
#include <osmo-bts/bts.h>
#include <osmo-bts/rsl.h>
#include <osmo-bts/oml.h>
#include <osmo-bts/abis.h>
#include <osmo-bts/bts_model.h>
#include <osmo-bts/handover.h>
#include <osmo-bts/power_control.h>
#include <osmo-bts/msg_utils.h>
#include <osmo-bts/pcuif_proto.h>
#include <osmo-bts/cbch.h>


#define CB_FCCH		-1
#define CB_SCH		-2
#define CB_BCCH		-3
#define CB_IDLE		-4

/* according to TS 05.02 Clause 7 Table 3 of 9 an Figure 8a */
static const int ccch_block_table[51] = {
	CB_FCCH, CB_SCH,/* 0..1 */
	CB_BCCH, CB_BCCH, CB_BCCH, CB_BCCH,	/* 2..5: BCCH */
	0, 0, 0, 0,	/* 6..9: B0 */
	CB_FCCH, CB_SCH,/* 10..11 */
	1, 1, 1, 1,	/* 12..15: B1 */
	2, 2, 2, 2,	/* 16..19: B2 */
	CB_FCCH, CB_SCH,/* 20..21 */
	3, 3, 3, 3,	/* 22..25: B3 */
	4, 4, 4, 4,	/* 26..29: B4 */
	CB_FCCH, CB_SCH,/* 30..31 */
	5, 5, 5, 5,	/* 32..35: B5 */
	6, 6, 6, 6,	/* 36..39: B6 */
	CB_FCCH, CB_SCH,/* 40..41 */
	7, 7, 7, 7, 	/* 42..45: B7 */
	8, 8, 8, 8, 	/* 46..49: B8 */
	-4		/* 50: Idle */
};

/* determine the CCCH block number based on the frame number */
unsigned int l1sap_fn2ccch_block(uint32_t fn)
{
	int rc = ccch_block_table[fn%51];
	/* if FN is negative, we were called for something that's not CCCH! */
	OSMO_ASSERT(rc >= 0);
	return rc;
}

struct gsm_lchan *get_lchan_by_chan_nr(struct gsm_bts_trx *trx,
				       unsigned int chan_nr)
{
	unsigned int tn, ss;

	tn = L1SAP_CHAN2TS(chan_nr);
	OSMO_ASSERT(tn < ARRAY_SIZE(trx->ts));

	if (L1SAP_IS_CHAN_CBCH(chan_nr))
		ss = 2; /* CBCH is always on sub-slot 2 */
	else
		ss = l1sap_chan2ss(chan_nr);
	OSMO_ASSERT(ss < ARRAY_SIZE(trx->ts[tn].lchan));

	return &trx->ts[tn].lchan[ss];
}

static struct gsm_lchan *
get_active_lchan_by_chan_nr(struct gsm_bts_trx *trx, unsigned int chan_nr)
{
	struct gsm_lchan *lchan = get_lchan_by_chan_nr(trx, chan_nr);

	if (lchan && lchan->state != LCHAN_S_ACTIVE) {
		LOGPLCHAN(lchan, DL1P, LOGL_NOTICE, "assuming active lchan, but state is %s\n",
			  gsm_lchans_name(lchan->state));
		return NULL;
	}
	return lchan;
}

static int l1sap_down(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap);

static uint32_t fn_ms_adj(uint32_t fn, const struct gsm_lchan *lchan)
{
	uint32_t samples_passed, r;

	if (lchan->tch.last_fn != LCHAN_FN_DUMMY) {
		/* 12/13 frames usable for audio in TCH,
		   160 samples per RTP packet,
		   1 RTP packet per 4 frames */
		samples_passed = (fn - lchan->tch.last_fn) * 12 * 160 / (13 * 4);
		/* round number of samples to the nearest multiple of
		   GSM_RTP_DURATION */
		r = samples_passed + GSM_RTP_DURATION / 2;
		r -= r % GSM_RTP_DURATION;

		if (r != GSM_RTP_DURATION)
			LOGPLCHAN(lchan, DRTP, LOGL_ERROR, "RTP clock out of sync with lower layer:"
				  " %"PRIu32" vs %d (%"PRIu32"->%"PRIu32")\n",
				  r, GSM_RTP_DURATION, lchan->tch.last_fn, fn);
	}
	return GSM_RTP_DURATION;
}

/*! limit number of queue entries to %u; drops any surplus messages */
static void queue_limit_to(const char *prefix, struct llist_head *queue, unsigned int limit)
{
	unsigned int count = llist_count(queue);

	if (count > limit)
		LOGP(DL1P, LOGL_NOTICE, "%s: freeing %d queued frames\n", prefix, count-limit);
	while (count > limit) {
		struct msgb *tmp = msgb_dequeue(queue);
		msgb_free(tmp);
		count--;
	}
}

/* allocate a msgb containing a osmo_phsap_prim + optional l2 data
 * in order to wrap femtobts header arround l2 data, there must be enough space
 * in front and behind data pointer */
struct msgb *l1sap_msgb_alloc(unsigned int l2_len)
{
	int headroom = 128;
	int size = headroom + sizeof(struct osmo_phsap_prim) + l2_len;
	struct msgb *msg = msgb_alloc_headroom(size, headroom, "l1sap_prim");

	if (!msg)
		return NULL;

	msg->l1h = msgb_put(msg, sizeof(struct osmo_phsap_prim));

	return msg;
}

int add_l1sap_header(struct gsm_bts_trx *trx, struct msgb *rmsg,
		     struct gsm_lchan *lchan, uint8_t chan_nr, uint32_t fn,
		     uint16_t ber10k, int16_t lqual_cb)
{
	struct osmo_phsap_prim *l1sap;

	LOGPLCHAN(lchan, DL1P, LOGL_DEBUG, "Rx -> RTP: %s\n", osmo_hexdump(rmsg->data, rmsg->len));

	rmsg->l2h = rmsg->data;
	rmsg->l1h = msgb_push(rmsg, sizeof(*l1sap));
	l1sap = msgb_l1sap_prim(rmsg);
	osmo_prim_init(&l1sap->oph, SAP_GSM_PH, PRIM_TCH, PRIM_OP_INDICATION,
		       rmsg);
	l1sap->u.tch.chan_nr = chan_nr;
	l1sap->u.tch.fn = fn;
	l1sap->u.tch.ber10k = ber10k;
	l1sap->u.tch.lqual_cb = lqual_cb;

	return l1sap_up(trx, l1sap);
}

static int l1sap_tx_ciph_req(struct gsm_bts_trx *trx, uint8_t chan_nr,
	uint8_t downlink, uint8_t uplink)
{
	struct osmo_phsap_prim l1sap_ciph;

	osmo_prim_init(&l1sap_ciph.oph, SAP_GSM_PH, PRIM_MPH_INFO,
		PRIM_OP_REQUEST, NULL);
	l1sap_ciph.u.info.type = PRIM_INFO_ACT_CIPH;
	l1sap_ciph.u.info.u.ciph_req.chan_nr = chan_nr;
	l1sap_ciph.u.info.u.ciph_req.downlink = downlink;
	l1sap_ciph.u.info.u.ciph_req.uplink = uplink;

	return l1sap_down(trx, &l1sap_ciph);
}


/* check if the message is a GSM48_MT_RR_CIPH_M_CMD, and if yes, enable
 * uni-directional de-cryption on the uplink. We need this ugly layering
 * violation as we have no way of passing down L3 metadata (RSL CIPHERING CMD)
 * to this point in L1 */
static int check_for_ciph_cmd(struct msgb *msg, struct gsm_lchan *lchan,
	uint8_t chan_nr)
{
	uint8_t n_s;

	/* only do this if we are in the right state */
	switch (lchan->ciph_state) {
	case LCHAN_CIPH_NONE:
	case LCHAN_CIPH_RX_REQ:
		break;
	default:
		return 0;
	}

	/* First byte (Address Field) of LAPDm header) */
	if (msg->data[0] != 0x03)
		return 0;
	/* First byte (protocol discriminator) of RR */
	if ((msg->data[3] & 0xF) != GSM48_PDISC_RR)
		return 0;
	/* 2nd byte (msg type) of RR */
	if ((msg->data[4] & 0x3F) != GSM48_MT_RR_CIPH_M_CMD)
		return 0;

	/* Remember N(S) + 1 to find the first ciphered frame */
	n_s = (msg->data[1] >> 1) & 0x7;
	lchan->ciph_ns = (n_s + 1) % 8;

	l1sap_tx_ciph_req(lchan->ts->trx, chan_nr, 0, 1);

	return 1;
}

/* public helpers for the test */
int bts_check_for_ciph_cmd(struct msgb *msg, struct gsm_lchan *lchan,
			   uint8_t chan_nr)
{
	return check_for_ciph_cmd(msg, lchan, chan_nr);
}

struct gsmtap_inst *gsmtap = NULL;
uint32_t gsmtap_sapi_mask = 0;
uint8_t gsmtap_sapi_acch = 0;

const struct value_string gsmtap_sapi_names[] = {
	{ GSMTAP_CHANNEL_BCCH,	"BCCH" },
	{ GSMTAP_CHANNEL_CCCH,	"CCCH" },
	{ GSMTAP_CHANNEL_RACH,	"RACH" },
	{ GSMTAP_CHANNEL_AGCH,	"AGCH" },
	{ GSMTAP_CHANNEL_PCH,	"PCH" },
	{ GSMTAP_CHANNEL_SDCCH,	"SDCCH" },
	{ GSMTAP_CHANNEL_TCH_F,	"TCH/F" },
	{ GSMTAP_CHANNEL_TCH_H,	"TCH/H" },
	{ GSMTAP_CHANNEL_PACCH,	"PACCH" },
	{ GSMTAP_CHANNEL_PDCH,	"PDTCH" },
	{ GSMTAP_CHANNEL_PTCCH,	"PTCCH" },
	{ GSMTAP_CHANNEL_CBCH51,"CBCH" },
	{ GSMTAP_CHANNEL_ACCH,  "SACCH" },
	{ 0, NULL }
};

/* send primitive as gsmtap */
static int gsmtap_ph_data(struct osmo_phsap_prim *l1sap, uint8_t *chan_type,
			  uint8_t *ss, uint32_t fn, uint8_t **data, unsigned int *len,
			  uint8_t num_agch)
{
	struct msgb *msg = l1sap->oph.msg;
	uint8_t chan_nr, link_id;

	*data = msgb_l2(msg);
	*len = msgb_l2len(msg);
	chan_nr = l1sap->u.data.chan_nr;
	link_id = l1sap->u.data.link_id;

	if (L1SAP_IS_CHAN_TCHF(chan_nr)) {
		*chan_type = GSMTAP_CHANNEL_TCH_F;
	} else if (L1SAP_IS_CHAN_TCHH(chan_nr)) {
		*ss = L1SAP_CHAN2SS_TCHH(chan_nr);
		*chan_type = GSMTAP_CHANNEL_TCH_H;
	} else if (L1SAP_IS_CHAN_SDCCH4(chan_nr)) {
		*ss = L1SAP_CHAN2SS_SDCCH4(chan_nr);
		*chan_type = GSMTAP_CHANNEL_SDCCH;
	} else if (L1SAP_IS_CHAN_SDCCH8(chan_nr)) {
		*ss = L1SAP_CHAN2SS_SDCCH8(chan_nr);
		*chan_type = GSMTAP_CHANNEL_SDCCH;
	} else if (L1SAP_IS_CHAN_BCCH(chan_nr)) {
		*chan_type = GSMTAP_CHANNEL_BCCH;
	} else if (L1SAP_IS_CHAN_AGCH_PCH(chan_nr)) {
		/* The sapi depends on DSP configuration, not
		 * on the actual SYSTEM INFORMATION 3. */
		if (l1sap_fn2ccch_block(fn) >= num_agch)
			*chan_type = GSMTAP_CHANNEL_PCH;
		else
			*chan_type = GSMTAP_CHANNEL_AGCH;
	} else if (L1SAP_IS_CHAN_CBCH(chan_nr)) {
		*chan_type = GSMTAP_CHANNEL_CBCH51;
	} else if (L1SAP_IS_CHAN_PDCH(chan_nr)) {
		*chan_type = GSMTAP_CHANNEL_PDTCH;
	}
	if (L1SAP_IS_LINK_SACCH(link_id))
		*chan_type |= GSMTAP_CHANNEL_ACCH;

	return 0;
}

static int gsmtap_pdch(struct osmo_phsap_prim *l1sap, uint8_t *chan_type,
		       uint8_t *ss, uint32_t fn, uint8_t **data, unsigned int *len)
{
	struct msgb *msg = l1sap->oph.msg;

	*data = msgb_l2(msg);
	*len = msgb_l2len(msg);

	if (L1SAP_IS_PTCCH(fn)) {
		*chan_type = GSMTAP_CHANNEL_PTCCH;
		*ss = L1SAP_FN2PTCCHBLOCK(fn);
		if (l1sap->oph.primitive == PRIM_OP_INDICATION) {
			OSMO_ASSERT(len > 0);
			if ((*data[0]) == 7)
				return -EINVAL;
			(*data)++;
			(*len)--;
		}
	} else
		*chan_type = GSMTAP_CHANNEL_PACCH;

	return 0;
}

static int gsmtap_ph_rach(struct osmo_phsap_prim *l1sap, uint8_t *chan_type,
	uint8_t *tn, uint8_t *ss, uint32_t *fn, uint8_t **data, unsigned int *len)
{
	uint8_t chan_nr;

	*chan_type = GSMTAP_CHANNEL_RACH;
	*fn = l1sap->u.rach_ind.fn;
	*tn = L1SAP_CHAN2TS(l1sap->u.rach_ind.chan_nr);
	chan_nr = l1sap->u.rach_ind.chan_nr;
	if (L1SAP_IS_CHAN_TCHH(chan_nr))
		*ss = L1SAP_CHAN2SS_TCHH(chan_nr);
	else if (L1SAP_IS_CHAN_SDCCH4(chan_nr))
		*ss = L1SAP_CHAN2SS_SDCCH4(chan_nr);
	else if (L1SAP_IS_CHAN_SDCCH8(chan_nr))
		*ss = L1SAP_CHAN2SS_SDCCH8(chan_nr);
	*data = (uint8_t *)&l1sap->u.rach_ind.ra;
	*len = 1;

	return 0;
}

/* Paging Request 1 with "no identity" content, i.e. empty/dummy paging */
static const uint8_t paging_fill[GSM_MACBLOCK_LEN] = {
	0x15, 0x06, 0x21, 0x00, 0x01, 0xf0, 0x2b, 0x2b, 0x2b, 0x2b,
	0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
	0x2b, 0x2b, 0x2b };

static bool is_fill_frame(uint8_t chan_type, const uint8_t *data, unsigned int len)
{
	switch (chan_type) {
	case GSMTAP_CHANNEL_AGCH:
		if (!memcmp(data, fill_frame, GSM_MACBLOCK_LEN))
			return true;
		break;
	case GSMTAP_CHANNEL_PCH:
		if (!memcmp(data, paging_fill, GSM_MACBLOCK_LEN))
			return true;
		break;
	/* don't use 'default' case here as the above only conditionally return true */
	}
	return false;
}

static int to_gsmtap(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap)
{
	uint8_t *data;
	unsigned int len;
	uint8_t chan_type = 0, tn = 0, ss = 0;
	uint32_t fn;
	uint16_t uplink = GSMTAP_ARFCN_F_UPLINK;
	int rc;

	if (!gsmtap)
		return 0;

	switch (OSMO_PRIM_HDR(&l1sap->oph)) {
	case OSMO_PRIM(PRIM_PH_DATA, PRIM_OP_REQUEST):
		uplink = 0;
		/* fall through */
	case OSMO_PRIM(PRIM_PH_DATA, PRIM_OP_INDICATION):
		fn = l1sap->u.data.fn;
		tn = L1SAP_CHAN2TS(l1sap->u.data.chan_nr);
		if (ts_is_pdch(&trx->ts[tn]))
			rc = gsmtap_pdch(l1sap, &chan_type, &ss, fn, &data,
					 &len);
		else
			rc = gsmtap_ph_data(l1sap, &chan_type, &ss, fn, &data,
					    &len, num_agch(trx, "GSMTAP"));
		break;
	case OSMO_PRIM(PRIM_PH_RACH, PRIM_OP_INDICATION):
		rc = gsmtap_ph_rach(l1sap, &chan_type, &tn, &ss, &fn, &data,
			&len);
		break;
	default:
		rc = -ENOTSUP;
	}

	if (rc)
		return rc;

	if (len == 0)
		return 0;
	if ((chan_type & GSMTAP_CHANNEL_ACCH)) {
		if (!gsmtap_sapi_acch)
			return 0;
	} else {
		if (!((1 << (chan_type & 31)) & gsmtap_sapi_mask))
			return 0;
	}

	/* don't log fill frames via GSMTAP; they serve no purpose other than
	 * to clog up your logs */
	if (is_fill_frame(chan_type, data, len))
		return 0;

	gsmtap_send(gsmtap, trx->arfcn | uplink, tn, chan_type, ss, fn, 0, 0,
		data, len);

	return 0;
}

/* Calculate the number of RACH slots that expire in a certain GSM frame
 * See also 3GPP TS 05.02 Clause 7 Table 5 of 9 */
static unsigned int calc_exprd_rach_frames(struct gsm_bts *bts, uint32_t fn)
{
	int rach_frames_expired = 0;
	uint8_t ccch_conf;
	struct gsm48_system_information_type_3 *si3;
	unsigned int blockno;

	si3 = GSM_BTS_SI(bts, SYSINFO_TYPE_3);
	ccch_conf = si3->control_channel_desc.ccch_conf;

	if (ccch_conf == RSL_BCCH_CCCH_CONF_1_C) {
		/* It is possible to combine a CCCH with an SDCCH4, in this
		 * case the CCCH will have to share the available frames with
		 * the other channel, this results in a limited number of
		 * available rach slots */
		blockno = fn % 51;
		if (blockno == 4 || blockno == 5
		    || (blockno >= 15 && blockno <= 36) || blockno == 45
		    || blockno == 46)
			rach_frames_expired = 1;
	} else {
		/* It is possible to have multiple CCCH channels on
		 * different physical channels (large cells), this
		 * also multiplies the available/expired RACH channels.
		 * See also TS 04.08, Chapter 10.5.2.11, table 10.29 */
		if (ccch_conf == RSL_BCCH_CCCH_CONF_2_NC)
			rach_frames_expired = 2;
		else if (ccch_conf == RSL_BCCH_CCCH_CONF_3_NC)
			rach_frames_expired = 3;
		else if (ccch_conf == RSL_BCCH_CCCH_CONF_4_NC)
			rach_frames_expired = 4;
		else
			rach_frames_expired = 1;
	}

	/* Each Frame has room for 4 RACH slots, since RACH
	 * slots are short enough to fit into a single radio
	 * burst, so we need to multiply the final result by 4 */
	return rach_frames_expired * 4;
}

/* time information received from bts model */
static int l1sap_info_time_ind(struct gsm_bts *bts,
			       struct osmo_phsap_prim *l1sap,
			       struct info_time_ind_param *info_time_ind)
{
	int frames_expired;

	DEBUGPFN(DL1P, info_time_ind->fn, "Rx MPH_INFO time ind\n");

	/* Calculate and check frame difference */
	frames_expired = info_time_ind->fn - bts->gsm_time.fn;
	if (frames_expired > 1) {
		if (bts->gsm_time.fn)
			LOGPFN(DL1P, LOGL_ERROR, info_time_ind->fn,
			     "Invalid condition detected: Frame difference is %"PRIu32"-%"PRIu32"=%d > 1!\n",
			     info_time_ind->fn, bts->gsm_time.fn, frames_expired);
	}

	/* Update our data structures with the current GSM time */
	gsm_fn2gsmtime(&bts->gsm_time, info_time_ind->fn);

	/* Update time on PCU interface */
	pcu_tx_time_ind(info_time_ind->fn);

	/* increment number of RACH slots that have passed by since the
	 * last time indication */
	bts->load.rach.total +=
	    calc_exprd_rach_frames(bts, info_time_ind->fn) * frames_expired;

	return 0;
}

static inline void set_ms_to_data(struct gsm_lchan *lchan, int16_t data, bool set_ms_to)
{
	if (!lchan)
		return;

	if (data + 63 > 255) { /* According to 3GPP TS 48.058 §9.3.37 Timing Offset field cannot exceed 255 */
		LOGPLCHAN(lchan, DL1P, LOGL_ERROR, "Attempting to set invalid Timing Offset value "
			  "%d (MS TO = %u)!\n", data, set_ms_to);
		return;
	}

	if (set_ms_to) {
		lchan->ms_t_offs = data + 63;
		lchan->p_offs = -1;
	} else {
		lchan->p_offs = data + 63;
		lchan->ms_t_offs = -1;
	}
}

/* measurement information received from bts model */
static int l1sap_info_meas_ind(struct gsm_bts_trx *trx,
	struct osmo_phsap_prim *l1sap,
	struct info_meas_ind_param *info_meas_ind)
{
	struct bts_ul_meas ulm;
	struct gsm_lchan *lchan;

	lchan = get_active_lchan_by_chan_nr(trx, info_meas_ind->chan_nr);
	if (!lchan) {
		LOGPFN(DL1P, LOGL_ERROR, info_meas_ind->fn,
			"No lchan for MPH INFO MEAS IND (chan_nr=%s)\n", rsl_chan_nr_str(info_meas_ind->chan_nr));
		return 0;
	}

	DEBUGPFN(DL1P, info_meas_ind->fn,
		"%s MPH_INFO meas ind, ta_offs_256bits=%d, ber10k=%d, inv_rssi=%u\n",
		gsm_lchan_name(lchan), info_meas_ind->ta_offs_256bits,
		info_meas_ind->ber10k, info_meas_ind->inv_rssi);

	/* in the GPRS case we are not interested in measurement
	 * processing.  The PCU will take care of it */
	if (lchan->type == GSM_LCHAN_PDTCH)
		return 0;

	memset(&ulm, 0, sizeof(ulm));
	ulm.ta_offs_256bits = info_meas_ind->ta_offs_256bits;
	ulm.ber10k = info_meas_ind->ber10k;
	ulm.inv_rssi = info_meas_ind->inv_rssi;
	ulm.is_sub = info_meas_ind->is_sub;

	/* we assume that symbol period is 1 bit: */
	set_ms_to_data(lchan, info_meas_ind->ta_offs_256bits / 256, true);

	lchan_meas_process_measurement(lchan, &ulm, info_meas_ind->fn);

	return 0;
}

/* any L1 MPH_INFO indication prim recevied from bts model */
static int l1sap_mph_info_ind(struct gsm_bts_trx *trx,
	 struct osmo_phsap_prim *l1sap, struct mph_info_param *info)
{
	int rc = 0;

	switch (info->type) {
	case PRIM_INFO_TIME:
		if (trx != trx->bts->c0) {
			LOGPFN(DL1P, LOGL_NOTICE, info->u.time_ind.fn,
				"BTS model is sending us PRIM_INFO_TIME for TRX %u, please fix it\n",
				trx->nr);
			rc = -1;
		} else
			rc = l1sap_info_time_ind(trx->bts, l1sap,
						 &info->u.time_ind);
		break;
	case PRIM_INFO_MEAS:
		rc = l1sap_info_meas_ind(trx, l1sap, &info->u.meas_ind);
		break;
	default:
		LOGP(DL1P, LOGL_NOTICE, "unknown MPH_INFO ind type %d\n",
			info->type);
		break;
	}

	return rc;
}

/* activation confirm received from bts model */
static int l1sap_info_act_cnf(struct gsm_bts_trx *trx,
	struct osmo_phsap_prim *l1sap,
	struct info_act_cnf_param *info_act_cnf)
{
	struct gsm_lchan *lchan = get_lchan_by_chan_nr(trx, info_act_cnf->chan_nr);

	LOGPLCHAN(lchan, DL1C, LOGL_INFO, "activate confirm chan_nr=%s trx=%d\n",
		  rsl_chan_nr_str(info_act_cnf->chan_nr), trx->nr);

	rsl_tx_chan_act_acknack(lchan, info_act_cnf->cause);

	/* During PDCH ACT, this is where we know that the PCU is done
	 * activating a PDCH, and PDCH switchover is complete.  See
	 * rsl_rx_dyn_pdch() */
	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_PDCH
	    && (lchan->ts->flags & TS_F_PDCH_ACT_PENDING))
		ipacc_dyn_pdch_complete(lchan->ts,
					info_act_cnf->cause? -EIO : 0);

	return 0;
}

/* activation confirm received from bts model */
static int l1sap_info_rel_cnf(struct gsm_bts_trx *trx,
	struct osmo_phsap_prim *l1sap,
	struct info_act_cnf_param *info_act_cnf)
{
	struct gsm_lchan *lchan = get_lchan_by_chan_nr(trx, info_act_cnf->chan_nr);

	LOGPLCHAN(lchan, DL1C, LOGL_INFO, "deactivate confirm chan_nr=%s trx=%d\n",
		  rsl_chan_nr_str(info_act_cnf->chan_nr), trx->nr);

	rsl_tx_rf_rel_ack(lchan);

	/* During PDCH DEACT, this marks the deactivation of the PDTCH as
	 * requested by the PCU. Next up, we disconnect the TS completely and
	 * call back to cb_ts_disconnected(). See rsl_rx_dyn_pdch(). */
	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_PDCH
	    && (lchan->ts->flags & TS_F_PDCH_DEACT_PENDING))
		bts_model_ts_disconnect(lchan->ts);

	return 0;
}

/* any L1 MPH_INFO confirm prim recevied from bts model */
static int l1sap_mph_info_cnf(struct gsm_bts_trx *trx,
	 struct osmo_phsap_prim *l1sap, struct mph_info_param *info)
{
	int rc = 0;

	switch (info->type) {
	case PRIM_INFO_ACTIVATE:
		rc = l1sap_info_act_cnf(trx, l1sap, &info->u.act_cnf);
		break;
	case PRIM_INFO_DEACTIVATE:
		rc = l1sap_info_rel_cnf(trx, l1sap, &info->u.act_cnf);
		break;
	default:
		LOGP(DL1C, LOGL_NOTICE, "unknown MPH_INFO cnf type %d\n",
			info->type);
		break;
	}

	return rc;
}

/*! handling for PDTCH loopback mode, used for BER testing
 *  \param[in] lchan logical channel on which we operate
 *  \param[in] rts_ind PH-RTS.ind from PHY which we process
 *  \param[out] msg Message buffer to which we write data
 *
 *  The function will fill \a msg, from which the caller can then
 *  subsequently build a PH-DATA.req */
static int lchan_pdtch_ph_rts_ind_loop(struct gsm_lchan *lchan,
					const struct ph_data_param *rts_ind,
					struct msgb *msg, const struct gsm_time *tm)
{
	struct msgb *loop_msg;
	uint8_t *p;

	/* de-queue response message (loopback) */
	loop_msg = msgb_dequeue(&lchan->dl_tch_queue);
	if (!loop_msg) {
		LOGPGT(DL1P, LOGL_NOTICE, tm, "%s: no looped PDTCH message, sending empty\n",
		     gsm_lchan_name(lchan));
		/* empty downlink message */
		p = msgb_put(msg, GSM_MACBLOCK_LEN);
		memset(p, 0, GSM_MACBLOCK_LEN);
	} else {
		LOGPGT(DL1P, LOGL_NOTICE, tm, "%s: looped PDTCH message of %u bytes\n",
		     gsm_lchan_name(lchan), msgb_l2len(loop_msg));
		/* copy over data from queued response message */
		p = msgb_put(msg, msgb_l2len(loop_msg));
		memcpy(p, msgb_l2(loop_msg), msgb_l2len(loop_msg));
		msgb_free(loop_msg);
	}
	return 0;
}

/* Check if given CCCH frame number is for a PCH or for an AGCH (this function is
 * only used internally, it is public to call it from unit-tests) */
int is_ccch_for_agch(struct gsm_bts_trx *trx, uint32_t fn) {
	/* Note: The number of available access grant channels is set by the
	 * parameter BS_AG_BLKS_RES via system information type 3. This SI is
	 * transfered to osmo-bts via RSL */
        return l1sap_fn2ccch_block(fn) < num_agch(trx, "PH-RTS-IND");
}

/* PH-RTS-IND prim received from bts model */
static int l1sap_ph_rts_ind(struct gsm_bts_trx *trx,
	struct osmo_phsap_prim *l1sap, struct ph_data_param *rts_ind)
{
	struct msgb *msg = l1sap->oph.msg;
	struct gsm_time g_time;
	struct gsm_lchan *lchan;
	uint8_t chan_nr, link_id;
	uint8_t tn;
	uint32_t fn;
	uint8_t *p, *si;
	struct lapdm_entity *le;
	struct osmo_phsap_prim pp;
	bool dtxd_facch = false;
	int rc;
	int is_ag_res;

	chan_nr = rts_ind->chan_nr;
	link_id = rts_ind->link_id;
	fn = rts_ind->fn;
	tn = L1SAP_CHAN2TS(chan_nr);

	gsm_fn2gsmtime(&g_time, fn);

	DEBUGPGT(DL1P, &g_time, "Rx PH-RTS.ind chan_nr=%s link_id=0x%02xd\n", rsl_chan_nr_str(chan_nr), link_id);

	/* reuse PH-RTS.ind for PH-DATA.req */
	if (!msg) {
		LOGPGT(DL1P, LOGL_FATAL, &g_time, "RTS without msg to be reused. Please fix!\n");
		abort();
	}
	msgb_trim(msg, sizeof(*l1sap));
	osmo_prim_init(&l1sap->oph, SAP_GSM_PH, PRIM_PH_DATA, PRIM_OP_REQUEST,
		msg);
	msg->l2h = msg->l1h + sizeof(*l1sap);

	if (ts_is_pdch(&trx->ts[tn])) {
		lchan = get_active_lchan_by_chan_nr(trx, chan_nr);
		if (lchan && lchan->loopback) {
			if (!L1SAP_IS_PTCCH(rts_ind->fn))
				lchan_pdtch_ph_rts_ind_loop(lchan, rts_ind, msg, &g_time);
			/* continue below like for SACCH/FACCH/... */
		} else {
			/* forward RTS.ind to PCU */
			if (L1SAP_IS_PTCCH(rts_ind->fn)) {
				pcu_tx_rts_req(&trx->ts[tn], 1, fn, 1 /* ARFCN */,
						L1SAP_FN2PTCCHBLOCK(fn));
			} else {
				pcu_tx_rts_req(&trx->ts[tn], 0, fn, 0 /* ARFCN */,
						L1SAP_FN2MACBLOCK(fn));
			}
			/* return early, PCU takes care of rest */
			return 0;
		}
	} else if (L1SAP_IS_CHAN_BCCH(chan_nr)) {
		p = msgb_put(msg, GSM_MACBLOCK_LEN);
		/* get them from bts->si_buf[] */
		si = bts_sysinfo_get(trx->bts, &g_time);
		if (si)
			memcpy(p, si, GSM_MACBLOCK_LEN);
		else
			memcpy(p, fill_frame, GSM_MACBLOCK_LEN);
	} else if (L1SAP_IS_CHAN_CBCH(chan_nr)) {
		p = msgb_put(msg, GSM_MACBLOCK_LEN);
		bts_cbch_get(trx->bts, p, &g_time);
	} else if (!(chan_nr & 0x80)) { /* only TCH/F, TCH/H, SDCCH/4 and SDCCH/8 have C5 bit cleared */
		lchan = get_active_lchan_by_chan_nr(trx, chan_nr);
		if (!lchan) {
			LOGPGT(DL1P, LOGL_ERROR, &g_time, "No lchan for PH-RTS.ind (chan_nr=%s)\n",
			       rsl_chan_nr_str(chan_nr));
			return 0;
		}
		if (L1SAP_IS_LINK_SACCH(link_id)) {
			p = msgb_put(msg, GSM_MACBLOCK_LEN);
			/* L1-header, if not set/modified by layer 1 */
			p[0] = lchan->ms_power_ctrl.current;
			p[1] = lchan->rqd_ta;
			le = &lchan->lapdm_ch.lapdm_acch;
		} else {
			if (lchan->ts->trx->bts->dtxd)
				dtxd_facch = true;
			le = &lchan->lapdm_ch.lapdm_dcch;
		}
		rc = lapdm_phsap_dequeue_prim(le, &pp);
		if (rc < 0) {
			if (L1SAP_IS_LINK_SACCH(link_id)) {
				/* No SACCH data from LAPDM pending, send SACCH filling */
				uint8_t *si = lchan_sacch_get(lchan);
				if (si) {
					/* The +2 is empty space where the DSP inserts the L1 hdr */
					memcpy(p + 2, si, GSM_MACBLOCK_LEN - 2);
				} else
					memcpy(p + 2, fill_frame, GSM_MACBLOCK_LEN - 2);
			} else if (L1SAP_IS_CHAN_SDCCH4(chan_nr) || L1SAP_IS_CHAN_SDCCH8(chan_nr) ||
				   (lchan->rsl_cmode == RSL_CMOD_SPD_SIGN && !lchan->ts->trx->bts->dtxd)) {
				/*
				 * SDCCH or TCH in signalling mode without DTX.
				 *
				 * Send fill frame according to GSM 05.08, section 8.3: "On the SDCCH and on the
				 * half rate speech traffic channel in signalling only mode DTX is not allowed.
				 * In these cases and during signalling on the TCH when DTX is not used, the same
				 * L2 fill frame shall be transmitted in case there is nothing else to transmit."
				 */
				p = msgb_put(msg, GSM_MACBLOCK_LEN);
				memcpy(p, fill_frame, GSM_MACBLOCK_LEN);
			} /* else the message remains empty, so TCH frames are sent */
		} else {
			/* The +2 is empty space where the DSP inserts the L1 hdr */
			if (L1SAP_IS_LINK_SACCH(link_id))
				memcpy(p + 2, pp.oph.msg->data + 2, GSM_MACBLOCK_LEN - 2);
			else {
				p = msgb_put(msg, GSM_MACBLOCK_LEN);
				memcpy(p, pp.oph.msg->data, GSM_MACBLOCK_LEN);
				/* check if it is a RR CIPH MODE CMD. if yes, enable RX ciphering */
				check_for_ciph_cmd(pp.oph.msg, lchan, chan_nr);
				if (dtxd_facch)
					dtx_dispatch(lchan, E_FACCH);
			}
			msgb_free(pp.oph.msg);
		}
	} else if (L1SAP_IS_CHAN_AGCH_PCH(chan_nr)) {
		p = msgb_put(msg, GSM_MACBLOCK_LEN);
		is_ag_res = is_ccch_for_agch(trx, fn);
		rc = bts_ccch_copy_msg(trx->bts, p, &g_time, is_ag_res);
		if (rc <= 0)
			memcpy(p, fill_frame, GSM_MACBLOCK_LEN);
	}

	DEBUGPGT(DL1P, &g_time, "Tx PH-DATA.req chan_nr=%s link_id=0x%02x\n", rsl_chan_nr_str(chan_nr), link_id);

	l1sap_down(trx, l1sap);

	/* don't free, because we forwarded data */
	return 1;
}

static bool rtppayload_is_octet_aligned(const uint8_t *rtp_pl, uint8_t payload_len)
{
	/*
	 * Logic: If 1st bit padding is not zero, packet is either:
	 * - bandwidth-efficient AMR payload.
	 * - malformed packet.
	 * However, Bandwidth-efficient AMR 4,75 frame last in payload(F=0, FT=0)
	 * with 4th,5ht,6th AMR payload to 0 matches padding==0.
	 * Furthermore, both AMR 4,75 bw-efficient and octet alignment are 14 bytes long (AMR 4,75 encodes 95b):
	 * bw-efficient: 95b, + 4b hdr + 6b ToC = 105b, + padding = 112b = 14B.
	 * octet-aligned: 1B hdr + 1B ToC + 95b = 111b, + padding = 112b = 14B.
	 * We cannot use other fields to match since they are inside the AMR
	 * payload bits which are unknown.
	 * As a result, this function may return false positive (true) for some AMR
	 * 4,75 AMR frames, but given the length, CMR and FT read is the same as a
	 * consequence, the damage in here is harmless other than being unable to
	 * decode the audio at the other side.
	 */
	#define AMR_PADDING1(rtp_pl) (rtp_pl[0] & 0x0f)
	#define AMR_PADDING2(rtp_pl) (rtp_pl[1] & 0x03)

	if(payload_len < 2 || AMR_PADDING1(rtp_pl) || AMR_PADDING2(rtp_pl))
		return false;

	return true;
}

static bool rtppayload_is_valid(struct gsm_lchan *lchan, struct msgb *resp_msg)
{
	/* Avoid sending bw-efficient AMR to lower layers, most bts models
	 * don't support it. */
	if(lchan->tch_mode == GSM48_CMODE_SPEECH_AMR &&
		!rtppayload_is_octet_aligned(resp_msg->data, resp_msg->len)) {
		LOGPLCHAN(lchan, DL1P, LOGL_NOTICE,
			  "RTP->L1: Dropping unexpected AMR encoding (bw-efficient?) %s\n",
			  osmo_hexdump(resp_msg->data, resp_msg->len));
		return false;
	}
	return true;
}

/* TCH-RTS-IND prim recevied from bts model */
static int l1sap_tch_rts_ind(struct gsm_bts_trx *trx,
	struct osmo_phsap_prim *l1sap, struct ph_tch_param *rts_ind)
{
	struct msgb *resp_msg;
	struct osmo_phsap_prim *resp_l1sap, empty_l1sap;
	struct gsm_time g_time;
	struct gsm_lchan *lchan;
	uint8_t chan_nr, marker = 0;
	uint32_t fn;
	int rc;

	chan_nr = rts_ind->chan_nr;
	fn = rts_ind->fn;

	gsm_fn2gsmtime(&g_time, fn);

	DEBUGPGT(DL1P, &g_time, "Rx TCH-RTS.ind chan_nr=%s\n", rsl_chan_nr_str(chan_nr));

	lchan = get_active_lchan_by_chan_nr(trx, chan_nr);
	if (!lchan) {
		LOGPGT(DL1P, LOGL_ERROR, &g_time, "No lchan for PH-RTS.ind (chan_nr=%s)\n", rsl_chan_nr_str(chan_nr));
		return 0;
	}

	if (!lchan->loopback && lchan->abis_ip.rtp_socket) {
		osmo_rtp_socket_poll(lchan->abis_ip.rtp_socket);
		/* FIXME: we _assume_ that we never miss TDMA
		 * frames and that we always get to this point
		 * for every to-be-transmitted voice frame.  A
		 * better solution would be to compute
		 * rx_user_ts based on how many TDMA frames have
		 * elapsed since the last call */
		lchan->abis_ip.rtp_socket->rx_user_ts += GSM_RTP_DURATION;
	}
	/* get a msgb from the dl_tx_queue */
	resp_msg = msgb_dequeue(&lchan->dl_tch_queue);
	if (!resp_msg) {
		DEBUGPGT(DL1P, &g_time, "%s DL TCH Tx queue underrun\n", gsm_lchan_name(lchan));
		resp_l1sap = &empty_l1sap;
	} else if(!rtppayload_is_valid(lchan, resp_msg)) {
		msgb_free(resp_msg);
		resp_msg = NULL;
		resp_l1sap = &empty_l1sap;
	} else {
		/* Obtain RTP header Marker bit from control buffer */
		marker = rtpmsg_marker_bit(resp_msg);

		resp_msg->l2h = resp_msg->data;
		msgb_push(resp_msg, sizeof(*resp_l1sap));
		resp_msg->l1h = resp_msg->data;
		resp_l1sap = msgb_l1sap_prim(resp_msg);
	}

	/* check for pending REL_IND */
	if (lchan->pending_rel_ind_msg) {
		LOGPGT(DRSL, LOGL_INFO, &g_time, "%s Forward REL_IND to L3\n", gsm_lchan_name(lchan));
		/* Forward it to L3 */
		rc = abis_bts_rsl_sendmsg(lchan->pending_rel_ind_msg);
		lchan->pending_rel_ind_msg = NULL;
		if (rc < 0)
			return rc;
	}

	memset(resp_l1sap, 0, sizeof(*resp_l1sap));
	osmo_prim_init(&resp_l1sap->oph, SAP_GSM_PH, PRIM_TCH, PRIM_OP_REQUEST,
		resp_msg);
	resp_l1sap->u.tch.chan_nr = chan_nr;
	resp_l1sap->u.tch.fn = fn;
	resp_l1sap->u.tch.marker = marker;

	DEBUGPGT(DL1P, &g_time, "Tx TCH.req chan_nr=%s\n", rsl_chan_nr_str(chan_nr));

	l1sap_down(trx, resp_l1sap);

	return 0;
}

/* process radio link timeout counter S. Follows TS 05.08 Section 5.2
 * "MS Procedure" as the "BSS Procedure [...] shall be determined by the
 * network operator." */
static void radio_link_timeout(struct gsm_lchan *lchan, int bad_frame)
{
	struct gsm_bts *bts = lchan->ts->trx->bts;

	/* Bypass radio link timeout if set to -1 */
	if (bts->radio_link_timeout < 0)
		return;

	/* if link loss criterion already reached */
	if (lchan->s == 0) {
		DEBUGP(DMEAS, "%s radio link counter S already 0.\n",
			gsm_lchan_name(lchan));
		return;
	}

	if (bad_frame) {
		/* count down radio link counter S */
		lchan->s--;
		DEBUGP(DMEAS, "%s counting down radio link counter S=%d\n",
			gsm_lchan_name(lchan), lchan->s);
		if (lchan->s == 0)
			rsl_tx_conn_fail(lchan, RSL_ERR_RADIO_LINK_FAIL);
		return;
	}

	if (lchan->s < bts->radio_link_timeout) {
		/* count up radio link counter S */
		lchan->s += 2;
		if (lchan->s > bts->radio_link_timeout)
			lchan->s = bts->radio_link_timeout;
		DEBUGP(DMEAS, "%s counting up radio link counter S=%d\n",
			gsm_lchan_name(lchan), lchan->s);
	}
}

static inline int check_for_first_ciphrd(struct gsm_lchan *lchan,
					  uint8_t *data, int len)
{
	uint8_t n_r;

	/* if this is the first valid message after enabling Rx
	 * decryption, we have to enable Tx encryption */
	if (lchan->ciph_state != LCHAN_CIPH_RX_CONF)
		return 0;

	/* HACK: check if it's an I frame, in order to
	 * ignore some still buffered/queued UI frames received
	 * before decryption was enabled */
	if (data[0] != 0x01)
		return 0;

	if ((data[1] & 0x01) != 0)
		return 0;

	n_r = data[1] >> 5;
	if (lchan->ciph_ns != n_r)
		return 0;

	return 1;
}

/* public helper for the test */
int bts_check_for_first_ciphrd(struct gsm_lchan *lchan,
				uint8_t *data, int len)
{
	return check_for_first_ciphrd(lchan, data, len);
}

/* DATA received from bts model */
static int l1sap_ph_data_ind(struct gsm_bts_trx *trx,
	 struct osmo_phsap_prim *l1sap, struct ph_data_param *data_ind)
{
	struct msgb *msg = l1sap->oph.msg;
	struct gsm_time g_time;
	struct gsm_lchan *lchan;
	struct lapdm_entity *le;
	uint8_t *data = msg->l2h;
	int len = msgb_l2len(msg);
	uint8_t chan_nr, link_id;
	uint8_t tn;
	uint32_t fn;
	int8_t rssi;
	enum osmo_ph_pres_info_type pr_info = data_ind->pdch_presence_info;

	rssi = data_ind->rssi;
	chan_nr = data_ind->chan_nr;
	link_id = data_ind->link_id;
	fn = data_ind->fn;
	tn = L1SAP_CHAN2TS(chan_nr);

	gsm_fn2gsmtime(&g_time, fn);

	DEBUGPGT(DL1P, &g_time, "Rx PH-DATA.ind chan_nr=%s link_id=0x%02x len=%d\n",
		 rsl_chan_nr_str(chan_nr), link_id, len);

	if (ts_is_pdch(&trx->ts[tn])) {
		lchan = get_lchan_by_chan_nr(trx, chan_nr);
		if (!lchan)
			LOGPGT(DL1P, LOGL_ERROR, &g_time, "No lchan for chan_nr=%s\n", rsl_chan_nr_str(chan_nr));
		if (lchan && lchan->loopback && !L1SAP_IS_PTCCH(fn)) {
			/* we are in loopback mode (for BER testing)
			 * mode and need to enqeue the frame to be
			 * returned in downlink */
			queue_limit_to(gsm_lchan_name(lchan), &lchan->dl_tch_queue, 1);
			msgb_enqueue(&lchan->dl_tch_queue, msg);

			/* Return 1 to signal that we're still using msg
			 * and it should not be freed */
			return 1;
		}

		/* don't send bad frames to PCU */
		if (len == 0)
			return -EINVAL;
		if (L1SAP_IS_PTCCH(fn)) {
			pcu_tx_data_ind(&trx->ts[tn], PCU_IF_SAPI_PTCCH, fn,
					0 /* ARFCN */, L1SAP_FN2PTCCHBLOCK(fn),
					data, len, rssi, data_ind->ber10k,
					data_ind->ta_offs_256bits/64,
					data_ind->lqual_cb);
		} else {
			/* drop incomplete UL block */
			if (pr_info != PRES_INFO_BOTH)
				return 0;
			/* PDTCH / PACCH frame handling */
			pcu_tx_data_ind(&trx->ts[tn], PCU_IF_SAPI_PDTCH, fn, 0 /* ARFCN */,
					L1SAP_FN2MACBLOCK(fn), data, len, rssi, data_ind->ber10k,
					data_ind->ta_offs_256bits/64, data_ind->lqual_cb);
		}
		return 0;
	}

	lchan = get_active_lchan_by_chan_nr(trx, chan_nr);
	if (!lchan) {
		LOGPGT(DL1P, LOGL_ERROR, &g_time, "No lchan for chan_nr=%s\n", rsl_chan_nr_str(chan_nr));
		return 0;
	}

	/* bad frame */
	if (len == 0) {
		if (L1SAP_IS_LINK_SACCH(link_id))
			radio_link_timeout(lchan, 1);
		return -EINVAL;
	}

	/* report first valid received frame to handover process */
	if (lchan->ho.active == HANDOVER_WAIT_FRAME)
		handover_frame(lchan);

	if (L1SAP_IS_LINK_SACCH(link_id)) {
		radio_link_timeout(lchan, 0);
		le = &lchan->lapdm_ch.lapdm_acch;
		/* save the SACCH L1 header in the lchan struct for RSL MEAS RES */
		if (len < 2) {
			LOGPGT(DL1P, LOGL_NOTICE, &g_time, "SACCH with size %u<2 !?!\n", len);
			return -EINVAL;
		}
		/* Some brilliant engineer decided that the ordering of
		 * fields on the Um interface is different from the
		 * order of fields in RLS. See TS 04.04 (Chapter 7.2)
		 * vs. TS 08.58 (Chapter 9.3.10). */
		lchan->meas.l1_info[0] = data[0] << 3;
		lchan->meas.l1_info[0] |= ((data[0] >> 5) & 1) << 2;
		lchan->meas.l1_info[1] = data[1];
		lchan->meas.flags |= LC_UL_M_F_L1_VALID;

		lchan_ms_pwr_ctrl(lchan, data[0] & 0x1f, data_ind->rssi);
	} else
		le = &lchan->lapdm_ch.lapdm_dcch;

	if (check_for_first_ciphrd(lchan, data, len))
		l1sap_tx_ciph_req(lchan->ts->trx, chan_nr, 1, 0);

	/* SDCCH, SACCH and FACCH all go to LAPDm */
	msgb_pull(msg, (msg->l2h - msg->data));
	msg->l1h = NULL;
	lapdm_phsap_up(&l1sap->oph, le);

	/* don't free, because we forwarded data */
	return 1;
}

/* TCH received from bts model */
static int l1sap_tch_ind(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap,
	struct ph_tch_param *tch_ind)
{
	struct gsm_bts *bts = trx->bts;
	struct msgb *msg = l1sap->oph.msg;
	struct gsm_time g_time;
	struct gsm_lchan *lchan;
	uint8_t  chan_nr;
	uint32_t fn;

	chan_nr = tch_ind->chan_nr;
	fn = tch_ind->fn;

	gsm_fn2gsmtime(&g_time, fn);

	LOGPGT(DL1P, LOGL_INFO, &g_time, "Rx TCH.ind chan_nr=%s\n", rsl_chan_nr_str(chan_nr));

	lchan = get_active_lchan_by_chan_nr(trx, chan_nr);
	if (!lchan) {
		LOGPGT(DL1P, LOGL_ERROR, &g_time, "No lchan for TCH.ind (chan_nr=%s)\n", rsl_chan_nr_str(chan_nr));
		return 0;
	}

	msgb_pull(msg, sizeof(*l1sap));

	/* Low level layers always call us when TCH content is expected, even if
	 * the content is not available due to decoding issues. Content not
	 * available is expected as empty payload. We also check if quality is
	 * good enough. */
	if (msg->len && tch_ind->lqual_cb / 10 >= bts->min_qual_norm) {
		/* hand msg to RTP code for transmission */
		if (lchan->abis_ip.rtp_socket)
			osmo_rtp_send_frame_ext(lchan->abis_ip.rtp_socket,
				msg->data, msg->len, fn_ms_adj(fn, lchan), lchan->rtp_tx_marker);
		/* if loopback is enabled, also queue received RTP data */
		if (lchan->loopback) {
			/* make sure the queue doesn't get too long */
			queue_limit_to(gsm_lchan_name(lchan), &lchan->dl_tch_queue, 1);
			/* add new frame to queue */
			msgb_enqueue(&lchan->dl_tch_queue, msg);
			/* Return 1 to signal that we're still using msg and it should not be freed */
			return 1;
		}
		/* Only clear the marker bit once we have sent a RTP packet with it */
		lchan->rtp_tx_marker = false;
	} else {
		DEBUGPGT(DRTP, &g_time, "Skipping RTP frame with lost payload (chan_nr=0x%02x)\n",
			 chan_nr);
		if (lchan->abis_ip.rtp_socket)
			osmo_rtp_skipped_frame(lchan->abis_ip.rtp_socket, fn_ms_adj(fn, lchan));
		lchan->rtp_tx_marker = true;
	}

	lchan->tch.last_fn = fn;
	return 0;
}

#define RACH_MIN_TOA256 -2 * 256

static bool rach_pass_filter(struct ph_rach_ind_param *rach_ind, struct gsm_bts *bts)
{
	int16_t toa256 = rach_ind->acc_delay_256bits;

	/* Check for RACH exceeding BER threshold (ghost RACH) */
	if (rach_ind->ber10k > bts->max_ber10k_rach) {
		LOGPFN(DL1C, LOGL_INFO, rach_ind->fn, "Ignoring RACH request: "
			"BER10k(%u) > BER10k_MAX(%u)\n",
			rach_ind->ber10k, bts->max_ber10k_rach);
		return false;
	}

	/**
	 * Make sure that ToA (Timing of Arrival) is acceptable.
	 * We allow early arrival up to 2 symbols, and delay
	 * according to maximal allowed Timing Advance value.
	 */
	if (toa256 < RACH_MIN_TOA256 || toa256 > bts->max_ta * 256) {
		LOGPFN(DL1C, LOGL_INFO, rach_ind->fn, "Ignoring RACH request: "
			"ToA(%d) exceeds the allowed range (%d..%d)\n",
			toa256, RACH_MIN_TOA256, bts->max_ta * 256);
		return false;
	}

	return true;
}

/* Special case where handover RACH is detected */
static int l1sap_handover_rach(struct gsm_bts_trx *trx,
	struct osmo_phsap_prim *l1sap, struct ph_rach_ind_param *rach_ind)
{
	/* Filter out noise / interference / ghosts */
	if (!rach_pass_filter(rach_ind, trx->bts)) {
		rate_ctr_inc2(trx->bts->ctrs, BTS_CTR_RACH_DROP);
		return 0;
	}

	handover_rach(get_lchan_by_chan_nr(trx, rach_ind->chan_nr),
		rach_ind->ra, rach_ind->acc_delay);

	/* must return 0, so in case of msg at l1sap, it will be freed */
	return 0;
}

/* RACH received from bts model */
static int l1sap_ph_rach_ind(struct gsm_bts_trx *trx,
	 struct osmo_phsap_prim *l1sap, struct ph_rach_ind_param *rach_ind)
{
	struct gsm_bts *bts = trx->bts;
	struct lapdm_channel *lc;

	DEBUGPFN(DL1P, rach_ind->fn, "Rx PH-RA.ind\n");

	/* check for handover access burst on dedicated channels */
	if (!L1SAP_IS_CHAN_RACH(rach_ind->chan_nr)) {
		rate_ctr_inc2(trx->bts->ctrs, BTS_CTR_RACH_HO);
		return l1sap_handover_rach(trx, l1sap, rach_ind);
	}

	rate_ctr_inc2(trx->bts->ctrs, BTS_CTR_RACH_RCVD);

	/* increment number of busy RACH slots, if required */
	if (rach_ind->rssi >= bts->load.rach.busy_thresh)
		bts->load.rach.busy++;

	/* Filter out noise / interference / ghosts */
	if (!rach_pass_filter(rach_ind, bts)) {
		rate_ctr_inc2(trx->bts->ctrs, BTS_CTR_RACH_DROP);
		return 0;
	}

	/* increment number of RACH slots with valid non-handover RACH burst */
	bts->load.rach.access++;

	lc = &trx->ts[0].lchan[CCCH_LCHAN].lapdm_ch;

	/* According to 3GPP TS 48.058 § 9.3.17 Access Delay is expressed same way as TA (number of symbols) */
	set_ms_to_data(get_lchan_by_chan_nr(trx, rach_ind->chan_nr),
		rach_ind->acc_delay, false);

	/* check for packet access */
	if ((trx == bts->c0 && L1SAP_IS_PACKET_RACH(rach_ind->ra)) ||
		(trx == bts->c0 && rach_ind->is_11bit)) {
		rate_ctr_inc2(trx->bts->ctrs, BTS_CTR_RACH_PS);

		LOGPFN(DL1P, LOGL_INFO, rach_ind->fn, "RACH for packet access (toa=%d, ra=%d)\n",
			rach_ind->acc_delay, rach_ind->ra);

		pcu_tx_rach_ind(bts, rach_ind->acc_delay << 2,
			rach_ind->ra, rach_ind->fn,
			rach_ind->is_11bit, rach_ind->burst_type);
		return 0;
	}

	LOGPFN(DL1P, LOGL_INFO, rach_ind->fn, "RACH for RR access (toa=%d, ra=%d)\n",
		rach_ind->acc_delay, rach_ind->ra);
	rate_ctr_inc2(trx->bts->ctrs, BTS_CTR_RACH_CS);
	lapdm_phsap_up(&l1sap->oph, &lc->lapdm_dcch);

	return 0;
}

/* Process any L1 prim received from bts model.
 *
 * This function takes ownership of the msgb.
 * If l1sap contains a msgb, it assumes that msgb->l2h was set by lower layer.
 */
int l1sap_up(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap)
{
	struct msgb *msg = l1sap->oph.msg;
	int rc = 0;

	switch (OSMO_PRIM_HDR(&l1sap->oph)) {
	case OSMO_PRIM(PRIM_MPH_INFO, PRIM_OP_INDICATION):
		rc = l1sap_mph_info_ind(trx, l1sap, &l1sap->u.info);
		break;
	case OSMO_PRIM(PRIM_MPH_INFO, PRIM_OP_CONFIRM):
		rc = l1sap_mph_info_cnf(trx, l1sap, &l1sap->u.info);
		break;
	case OSMO_PRIM(PRIM_PH_RTS, PRIM_OP_INDICATION):
		rc = l1sap_ph_rts_ind(trx, l1sap, &l1sap->u.data);
		break;
	case OSMO_PRIM(PRIM_TCH_RTS, PRIM_OP_INDICATION):
		rc = l1sap_tch_rts_ind(trx, l1sap, &l1sap->u.tch);
		break;
	case OSMO_PRIM(PRIM_PH_DATA, PRIM_OP_INDICATION):
		to_gsmtap(trx, l1sap);
		rc = l1sap_ph_data_ind(trx, l1sap, &l1sap->u.data);
		break;
	case OSMO_PRIM(PRIM_TCH, PRIM_OP_INDICATION):
		rc = l1sap_tch_ind(trx, l1sap, &l1sap->u.tch);
		break;
	case OSMO_PRIM(PRIM_PH_RACH, PRIM_OP_INDICATION):
		to_gsmtap(trx, l1sap);
		rc = l1sap_ph_rach_ind(trx, l1sap, &l1sap->u.rach_ind);
		break;
	default:
		LOGP(DL1P, LOGL_NOTICE, "unknown prim %d op %d\n",
			l1sap->oph.primitive, l1sap->oph.operation);
		oml_tx_failure_event_rep(&trx->mo, OSMO_EVT_MAJ_UKWN_MSG,
					 "unknown prim %d op %d",
					 l1sap->oph.primitive,
					 l1sap->oph.operation);
		break;
	}

	/* Special return value '1' means: do not free */
	if (rc != 1)
		msgb_free(msg);

	return rc;
}

/* any L1 prim sent to bts model */
static int l1sap_down(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap)
{
	if (OSMO_PRIM_HDR(&l1sap->oph) ==
				 OSMO_PRIM(PRIM_PH_DATA, PRIM_OP_REQUEST))
		to_gsmtap(trx, l1sap);

	return bts_model_l1sap_down(trx, l1sap);
}

/* pcu (socket interface) sends us a data request primitive */
int l1sap_pdch_req(struct gsm_bts_trx_ts *ts, int is_ptcch, uint32_t fn,
	uint16_t arfcn, uint8_t block_nr, const uint8_t *data, uint8_t len)
{
	struct msgb *msg;
	struct osmo_phsap_prim *l1sap;
	struct gsm_time g_time;

	gsm_fn2gsmtime(&g_time, fn);

	DEBUGP(DL1P, "TX packet data %s is_ptcch=%d trx=%d ts=%d "
		"block_nr=%d, arfcn=%d, len=%d\n", osmo_dump_gsmtime(&g_time),
		is_ptcch, ts->trx->nr, ts->nr, block_nr, arfcn, len);

	msg = l1sap_msgb_alloc(len);
	l1sap = msgb_l1sap_prim(msg);
	osmo_prim_init(&l1sap->oph, SAP_GSM_PH, PRIM_PH_DATA, PRIM_OP_REQUEST,
		msg);
	l1sap->u.data.chan_nr = RSL_CHAN_OSMO_PDCH | ts->nr;
	l1sap->u.data.link_id = 0x00;
	l1sap->u.data.fn = fn;
	msg->l2h = msgb_put(msg, len);
	memcpy(msg->l2h, data, len);

	return l1sap_down(ts->trx, l1sap);
}

/*! \brief call-back function for incoming RTP */
void l1sap_rtp_rx_cb(struct osmo_rtp_socket *rs, const uint8_t *rtp_pl,
                     unsigned int rtp_pl_len, uint16_t seq_number,
		     uint32_t timestamp, bool marker)
{
	struct gsm_lchan *lchan = rs->priv;
	struct msgb *msg;
	struct osmo_phsap_prim *l1sap;

	/* if we're in loopback mode, we don't accept frames from the
	 * RTP socket anymore */
	if (lchan->loopback)
		return;

	msg = l1sap_msgb_alloc(rtp_pl_len);
	if (!msg)
		return;
	memcpy(msgb_put(msg, rtp_pl_len), rtp_pl, rtp_pl_len);
	msgb_pull(msg, sizeof(*l1sap));

	/* Store RTP header Marker bit in control buffer */
	rtpmsg_marker_bit(msg) = marker;
	/* Store RTP header Sequence Number in control buffer */
	rtpmsg_seq(msg) = seq_number;
	/* Store RTP header Timestamp in control buffer */
	rtpmsg_ts(msg) = timestamp;

	/* make sure the queue doesn't get too long */
	queue_limit_to(gsm_lchan_name(lchan), &lchan->dl_tch_queue, 1);

	msgb_enqueue(&lchan->dl_tch_queue, msg);
}

static int l1sap_chan_act_dact_modify(struct gsm_bts_trx *trx, uint8_t chan_nr,
		enum osmo_mph_info_type type, uint8_t sacch_only)
{
	struct osmo_phsap_prim l1sap;

	memset(&l1sap, 0, sizeof(l1sap));
	osmo_prim_init(&l1sap.oph, SAP_GSM_PH, PRIM_MPH_INFO, PRIM_OP_REQUEST,
		NULL);
	l1sap.u.info.type = type;
	l1sap.u.info.u.act_req.chan_nr = chan_nr;
	l1sap.u.info.u.act_req.sacch_only = sacch_only;

	return l1sap_down(trx, &l1sap);
}

int l1sap_chan_act(struct gsm_bts_trx *trx, uint8_t chan_nr, struct tlv_parsed *tp)
{
	struct gsm_lchan *lchan = get_lchan_by_chan_nr(trx, chan_nr);
	struct gsm48_chan_desc *cd;
	int rc;

	LOGPLCHAN(lchan, DL1C, LOGL_INFO, "activating channel chan_nr=%s trx=%d\n",
		  rsl_chan_nr_str(chan_nr), trx->nr);

	/* osmo-pcu calls this without a valid 'tp' parameter, so we
	 * need to make sure ew don't crash here */
	if (tp && TLVP_PRESENT(tp, GSM48_IE_CHANDESC_2) &&
	    TLVP_LEN(tp, GSM48_IE_CHANDESC_2) >= sizeof(*cd)) {
		cd = (struct gsm48_chan_desc *)
		TLVP_VAL(tp, GSM48_IE_CHANDESC_2);

		/* our L1 only supports one global TSC for all channels
		 * one one TRX, so we need to make sure not to activate
		 * channels with a different TSC!! */
		if (cd->h0.tsc != (lchan->ts->trx->bts->bsic & 7)) {
			LOGPLCHAN(lchan, DL1C, LOGL_ERROR, "lchan TSC %u != BSIC-TSC %u\n",
				  cd->h0.tsc, lchan->ts->trx->bts->bsic & 7);
			return -RSL_ERR_SERV_OPT_UNIMPL;
		}
	}

	lchan->sacch_deact = 0;
	lchan->s = lchan->ts->trx->bts->radio_link_timeout;

	rc = l1sap_chan_act_dact_modify(trx, chan_nr, PRIM_INFO_ACTIVATE, 0);
	if (rc)
		return -RSL_ERR_EQUIPMENT_FAIL;

	/* Init DTX DL FSM if necessary */
	if (trx->bts->dtxd && lchan->type != GSM_LCHAN_SDCCH) {
		char name[32];
		snprintf(name, sizeof(name), "bts%u-trx%u-ts%u-ss%u", lchan->ts->trx->bts->nr,
			 lchan->ts->trx->nr, lchan->ts->nr, lchan->nr);
		lchan->tch.dtx.dl_amr_fsm = osmo_fsm_inst_alloc(&dtx_dl_amr_fsm,
								tall_bts_ctx,
								lchan,
								LOGL_DEBUG,
								name);
		if (!lchan->tch.dtx.dl_amr_fsm) {
			l1sap_chan_act_dact_modify(trx, chan_nr, PRIM_INFO_DEACTIVATE, 0);
			return -RSL_ERR_EQUIPMENT_FAIL;
		}
	}
	return 0;
}

int l1sap_chan_rel(struct gsm_bts_trx *trx, uint8_t chan_nr)
{
	struct gsm_lchan *lchan = get_lchan_by_chan_nr(trx, chan_nr);
	LOGPLCHAN(lchan, DL1C, LOGL_INFO, "deactivating channel chan_nr=%s trx=%d\n",
		  rsl_chan_nr_str(chan_nr), trx->nr);

	if (lchan->tch.dtx.dl_amr_fsm) {
		osmo_fsm_inst_free(lchan->tch.dtx.dl_amr_fsm);
		lchan->tch.dtx.dl_amr_fsm = NULL;
	}

	return l1sap_chan_act_dact_modify(trx, chan_nr, PRIM_INFO_DEACTIVATE,
		0);
}

int l1sap_chan_deact_sacch(struct gsm_bts_trx *trx, uint8_t chan_nr)
{
	struct gsm_lchan *lchan = get_lchan_by_chan_nr(trx, chan_nr);

	LOGPLCHAN(lchan, DL1C, LOGL_INFO, "deactivating sacch chan_nr=%s trx=%d\n",
		  rsl_chan_nr_str(chan_nr), trx->nr);

	lchan->sacch_deact = 1;

	return l1sap_chan_act_dact_modify(trx, chan_nr, PRIM_INFO_DEACTIVATE,
		1);
}

int l1sap_chan_modify(struct gsm_bts_trx *trx, uint8_t chan_nr)
{
	LOGP(DL1C, LOGL_INFO, "modifying channel chan_nr=%s trx=%d\n",
		rsl_chan_nr_str(chan_nr), trx->nr);

	return l1sap_chan_act_dact_modify(trx, chan_nr, PRIM_INFO_MODIFY, 0);
}