openbsc/src/libbsc/abis_rsl.c

/* GSM Radio Signalling Link messages on the A-bis interface
 * 3GPP TS 08.58 version 8.6.0 Release 1999 / ETSI TS 100 596 V8.6.0 */

/* (C) 2008-2010 by Harald Welte <laforge@gnumonks.org>
 * (C) 2012 by 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 <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <openbsc/gsm_data.h>
#include <openbsc/gsm_04_08.h>
#include <osmocom/gsm/gsm_utils.h>
#include <openbsc/abis_rsl.h>
#include <openbsc/chan_alloc.h>
#include <openbsc/bsc_rll.h>
#include <openbsc/debug.h>
#include <osmocom/gsm/tlv.h>
#include <osmocom/gsm/protocol/gsm_04_08.h>
#include <osmocom/gsm/protocol/gsm_08_58.h>
#include <openbsc/paging.h>
#include <openbsc/signal.h>
#include <openbsc/meas_rep.h>
#include <openbsc/rtp_proxy.h>
#include <osmocom/abis/e1_input.h>
#include <osmocom/gsm/rsl.h>
#include <osmocom/core/talloc.h>

#define RSL_ALLOC_SIZE		1024
#define RSL_ALLOC_HEADROOM	128

enum sacch_deact {
	SACCH_NONE,
	SACCH_DEACTIVATE,
};

static int rsl_send_imm_assignment(struct gsm_lchan *lchan);
static void error_timeout_cb(void *data);
static int dyn_ts_switchover_continue(struct gsm_bts_trx_ts *ts);
static int dyn_ts_switchover_failed(struct gsm_bts_trx_ts *ts, int rc);
static void dyn_ts_switchover_complete(struct gsm_lchan *lchan);

static void send_lchan_signal(int sig_no, struct gsm_lchan *lchan,
			      struct gsm_meas_rep *resp)
{
	struct lchan_signal_data sig;
	sig.lchan = lchan;
	sig.mr = resp;
	osmo_signal_dispatch(SS_LCHAN, sig_no, &sig);
}

static void do_lchan_free(struct gsm_lchan *lchan)
{
	/* We start the error timer to make the channel available again */
	if (lchan->state == LCHAN_S_REL_ERR) {
		lchan->error_timer.data = lchan;
		lchan->error_timer.cb = error_timeout_cb;
		osmo_timer_schedule(&lchan->error_timer,
				   lchan->ts->trx->bts->network->T3111 + 2, 0);
	} else {
		rsl_lchan_set_state(lchan, LCHAN_S_NONE);
	}
	lchan_free(lchan);
}

static void count_codecs(struct gsm_bts *bts, struct gsm_lchan *lchan)
{
	OSMO_ASSERT(bts);

	if (lchan->type == GSM_LCHAN_TCH_H) {
		switch (lchan->tch_mode) {
		case GSM48_CMODE_SPEECH_AMR:
			rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_CODEC_AMR_H]);
			break;
		case GSM48_CMODE_SPEECH_V1:
			rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_CODEC_V1_HR]);
			break;
		default:
			break;
		}
	} else if (lchan->type == GSM_LCHAN_TCH_F) {
		switch (lchan->tch_mode) {
		case GSM48_CMODE_SPEECH_AMR:
			rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_CODEC_AMR_F]);
			break;
		case GSM48_CMODE_SPEECH_V1:
			rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_CODEC_V1_FR]);
			break;
		case GSM48_CMODE_SPEECH_EFR:
			rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_CODEC_EFR]);
			break;
		default:
			break;
		}
	}
}

static uint8_t mdisc_by_msgtype(uint8_t msg_type)
{
	/* mask off the transparent bit ? */
	msg_type &= 0xfe;

	if ((msg_type & 0xf0) == 0x00)
		return ABIS_RSL_MDISC_RLL;
	if ((msg_type & 0xf0) == 0x10) {
		if (msg_type >= 0x19 && msg_type <= 0x22)
			return ABIS_RSL_MDISC_TRX;
		else
			return ABIS_RSL_MDISC_COM_CHAN;
	}
	if ((msg_type & 0xe0) == 0x20)
		return ABIS_RSL_MDISC_DED_CHAN;
	
	return ABIS_RSL_MDISC_LOC;
}

static inline void init_dchan_hdr(struct abis_rsl_dchan_hdr *dh,
				  uint8_t msg_type)
{
	dh->c.msg_discr = mdisc_by_msgtype(msg_type);
	dh->c.msg_type = msg_type;
	dh->ie_chan = RSL_IE_CHAN_NR;
}

/* call rsl_lchan_lookup and set the log context */
static struct gsm_lchan *lchan_lookup(struct gsm_bts_trx *trx, uint8_t chan_nr,
				      const char *log_name)
{
	int rc;
	struct gsm_lchan *lchan = rsl_lchan_lookup(trx, chan_nr, &rc);

	if (!lchan) {
		LOGP(DRSL, LOGL_ERROR, "%sunknown chan_nr=0x%02x\n",
		     log_name, chan_nr);
		return NULL;
	}

	if (rc < 0)
		LOGP(DRSL, LOGL_ERROR, "%s %smismatching chan_nr=0x%02x\n",
		     gsm_ts_and_pchan_name(lchan->ts), log_name, chan_nr);

	log_set_context(BSC_CTX_LCHAN, lchan);
	if (lchan->conn)
		log_set_context(BSC_CTX_SUBSCR, lchan->conn->subscr);

	return lchan;
}

/* As per TS 03.03 Section 2.2, the IMSI has 'not more than 15 digits' */
uint64_t str_to_imsi(const char *imsi_str)
{
	uint64_t ret;

	ret = strtoull(imsi_str, NULL, 10);

	return ret;
}

static struct msgb *rsl_msgb_alloc(void)
{
	return msgb_alloc_headroom(RSL_ALLOC_SIZE, RSL_ALLOC_HEADROOM,
				   "RSL");
}

#define MACBLOCK_SIZE	23
static void pad_macblock(uint8_t *out, const uint8_t *in, int len)
{
	memcpy(out, in, len);

	if (len < MACBLOCK_SIZE)
		memset(out+len, 0x2b, MACBLOCK_SIZE-len);
}

/* Chapter 9.3.7: Encryption Information */
static int build_encr_info(uint8_t *out, struct gsm_lchan *lchan)
{
	*out++ = lchan->encr.alg_id & 0xff;
	if (lchan->encr.key_len)
		memcpy(out, lchan->encr.key, lchan->encr.key_len);
	return lchan->encr.key_len + 1;
}

static void print_rsl_cause(int lvl, const uint8_t *cause_v, uint8_t cause_len)
{
	int i;

	LOGPC(DRSL, lvl, "CAUSE=0x%02x(%s) ",
		cause_v[0], rsl_err_name(cause_v[0]));
	for (i = 1; i < cause_len-1; i++)
		LOGPC(DRSL, lvl, "%02x ", cause_v[i]);
}

static void lchan_act_tmr_cb(void *data)
{
	struct gsm_lchan *lchan = data;

	rsl_lchan_mark_broken(lchan, "activation timeout");
	lchan_free(lchan);
}

static void lchan_deact_tmr_cb(void *data)
{
	struct gsm_lchan *lchan = data;

	rsl_lchan_mark_broken(lchan, "de-activation timeout");
	lchan_free(lchan);
}


/* Send a BCCH_INFO message as per Chapter 8.5.1 */
int rsl_bcch_info(struct gsm_bts_trx *trx, uint8_t type,
		  const uint8_t *data, int len)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg = rsl_msgb_alloc();

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof*dh);
	init_dchan_hdr(dh, RSL_MT_BCCH_INFO);
	dh->chan_nr = RSL_CHAN_BCCH;

	msgb_tv_put(msg, RSL_IE_SYSINFO_TYPE, type);
	msgb_tlv_put(msg, RSL_IE_FULL_BCCH_INFO, len, data);

	msg->dst = trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

int rsl_sacch_filling(struct gsm_bts_trx *trx, uint8_t type,
		      const uint8_t *data, int len)
{
	struct abis_rsl_common_hdr *ch;
	struct msgb *msg = rsl_msgb_alloc();

	ch = (struct abis_rsl_common_hdr *) msgb_put(msg, sizeof(*ch));
	ch->msg_discr = ABIS_RSL_MDISC_TRX;
	ch->msg_type = RSL_MT_SACCH_FILL;

	msgb_tv_put(msg, RSL_IE_SYSINFO_TYPE, type);
	msgb_tl16v_put(msg, RSL_IE_L3_INFO, len, data);

	msg->dst = trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

int rsl_sacch_info_modify(struct gsm_lchan *lchan, uint8_t type,
			  const uint8_t *data, int len)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg = rsl_msgb_alloc();
	uint8_t chan_nr = gsm_lchan2chan_nr(lchan);

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_SACCH_INFO_MODIFY);
	dh->chan_nr = chan_nr;

	msgb_tv_put(msg, RSL_IE_SYSINFO_TYPE, type);
	msgb_tl16v_put(msg, RSL_IE_L3_INFO, len, data);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

int rsl_chan_bs_power_ctrl(struct gsm_lchan *lchan, unsigned int fpc, int db)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg;
	uint8_t chan_nr = gsm_lchan2chan_nr(lchan);

	db = abs(db);
	if (db > 30)
		return -EINVAL;

	msg = rsl_msgb_alloc();

	lchan->bs_power = db/2;
	if (fpc)
		lchan->bs_power |= 0x10;
	
	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_BS_POWER_CONTROL);
	dh->chan_nr = chan_nr;

	msgb_tv_put(msg, RSL_IE_BS_POWER, lchan->bs_power);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

int rsl_chan_ms_power_ctrl(struct gsm_lchan *lchan, unsigned int fpc, int dbm)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg;
	uint8_t chan_nr = gsm_lchan2chan_nr(lchan);
	int ctl_lvl;

	ctl_lvl = ms_pwr_ctl_lvl(lchan->ts->trx->bts->band, dbm);
	if (ctl_lvl < 0)
		return ctl_lvl;

	msg = rsl_msgb_alloc();

	lchan->ms_power = ctl_lvl;

	if (fpc)
		lchan->ms_power |= 0x20;
	
	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_MS_POWER_CONTROL);
	dh->chan_nr = chan_nr;

	msgb_tv_put(msg, RSL_IE_MS_POWER, lchan->ms_power);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

static int channel_mode_from_lchan(struct rsl_ie_chan_mode *cm,
				   struct gsm_lchan *lchan)
{
	memset(cm, 0, sizeof(*cm));

	/* FIXME: what to do with data calls ? */
	cm->dtx_dtu = 0;
	if (lchan->ts->trx->bts->dtxu != GSM48_DTX_SHALL_NOT_BE_USED)
		cm->dtx_dtu |= RSL_CMOD_DTXu;
	if (lchan->ts->trx->bts->dtxd)
		cm->dtx_dtu |= RSL_CMOD_DTXd;

	/* set TCH Speech/Data */
	cm->spd_ind = lchan->rsl_cmode;

	if (lchan->rsl_cmode == RSL_CMOD_SPD_SIGN &&
	    lchan->tch_mode != GSM48_CMODE_SIGN)
		LOGP(DRSL, LOGL_ERROR, "unsupported: rsl_mode == signalling, "
			"but tch_mode != signalling\n");

	switch (lchan->type) {
	case GSM_LCHAN_SDCCH:
		cm->chan_rt = RSL_CMOD_CRT_SDCCH;
		break;
	case GSM_LCHAN_TCH_F:
		cm->chan_rt = RSL_CMOD_CRT_TCH_Bm;
		break;
	case GSM_LCHAN_TCH_H:
		cm->chan_rt = RSL_CMOD_CRT_TCH_Lm;
		break;
	case GSM_LCHAN_NONE:
	case GSM_LCHAN_UNKNOWN:
	default:
		LOGP(DRSL, LOGL_ERROR,
		     "unsupported activation lchan->type %u %s\n",
		     lchan->type, gsm_lchant_name(lchan->type));
		return -EINVAL;
	}

	switch (lchan->tch_mode) {
	case GSM48_CMODE_SIGN:
		cm->chan_rate = 0;
		break;
	case GSM48_CMODE_SPEECH_V1:
		cm->chan_rate = RSL_CMOD_SP_GSM1;
		break;
	case GSM48_CMODE_SPEECH_EFR:
		cm->chan_rate = RSL_CMOD_SP_GSM2;
		break;
	case GSM48_CMODE_SPEECH_AMR:
		cm->chan_rate = RSL_CMOD_SP_GSM3;
		break;
	case GSM48_CMODE_DATA_14k5:
	case GSM48_CMODE_DATA_12k0:
	case GSM48_CMODE_DATA_6k0:
		switch (lchan->csd_mode) {
		case LCHAN_CSD_M_NT:
			/* non-transparent CSD with RLP */
			switch (lchan->tch_mode) {
			case GSM48_CMODE_DATA_14k5:
				cm->chan_rate = RSL_CMOD_SP_NT_14k5;
				break;
			case GSM48_CMODE_DATA_12k0:
				cm->chan_rate = RSL_CMOD_SP_NT_12k0;
				break;
			case GSM48_CMODE_DATA_6k0:
				cm->chan_rate = RSL_CMOD_SP_NT_6k0;
				break;
			default:
				LOGP(DRSL, LOGL_ERROR,
				     "unsupported lchan->tch_mode %u\n",
				     lchan->tch_mode);
				return -EINVAL;
			}
			break;
			/* transparent data services below */
		case LCHAN_CSD_M_T_1200_75:
			cm->chan_rate = RSL_CMOD_CSD_T_1200_75;
			break;
		case LCHAN_CSD_M_T_600:
			cm->chan_rate = RSL_CMOD_CSD_T_600;
			break;
		case LCHAN_CSD_M_T_1200:
			cm->chan_rate = RSL_CMOD_CSD_T_1200;
			break;
		case LCHAN_CSD_M_T_2400:
			cm->chan_rate = RSL_CMOD_CSD_T_2400;
			break;
		case LCHAN_CSD_M_T_9600:
			cm->chan_rate = RSL_CMOD_CSD_T_9600;
			break;
		case LCHAN_CSD_M_T_14400:
			cm->chan_rate = RSL_CMOD_CSD_T_14400;
			break;
		case LCHAN_CSD_M_T_29000:
			cm->chan_rate = RSL_CMOD_CSD_T_29000;
			break;
		case LCHAN_CSD_M_T_32000:
			cm->chan_rate = RSL_CMOD_CSD_T_32000;
			break;
		default:
			LOGP(DRSL, LOGL_ERROR,
			     "unsupported lchan->csd_mode %u\n",
			     lchan->csd_mode);
			return -EINVAL;
		}
	default:
		LOGP(DRSL, LOGL_ERROR,
		     "unsupported lchan->tch_mode %u\n",
		     lchan->tch_mode);
		return -EINVAL;
	}

	return 0;
}

static void mr_config_for_bts(struct gsm_lchan *lchan, struct msgb *msg)
{
	if (lchan->tch_mode == GSM48_CMODE_SPEECH_AMR)
		msgb_tlv_put(msg, RSL_IE_MR_CONFIG, lchan->mr_bts_lv[0],
			     lchan->mr_bts_lv + 1);
}

static enum gsm_phys_chan_config pchan_for_lchant(enum gsm_chan_t type)
{
	switch (type) {
	case GSM_LCHAN_TCH_F:
		return GSM_PCHAN_TCH_F;
	case GSM_LCHAN_TCH_H:
		return GSM_PCHAN_TCH_H;
	case GSM_LCHAN_NONE:
	case GSM_LCHAN_PDTCH:
		/* TODO: so far lchan->type is NONE in PDCH mode. PDTCH is only
		 * used in osmo-bts. Maybe set PDTCH and drop the NONE case
		 * here. */
		return GSM_PCHAN_PDCH;
	default:
		return GSM_PCHAN_UNKNOWN;
	}
}

/*! Tx simplified channel activation message for non-standard PDCH type. */
static int rsl_chan_activate_lchan_as_pdch(struct gsm_lchan *lchan)
{
	struct msgb *msg;
	struct abis_rsl_dchan_hdr *dh;

	/* This might be called after release of the second lchan of a TCH/H,
	 * but PDCH activation must always happen on the first lchan. Make sure
	 * the calling code passes the correct lchan. */
	OSMO_ASSERT(lchan == lchan->ts->lchan);

	rsl_lchan_set_state(lchan, LCHAN_S_ACT_REQ);

	msg = rsl_msgb_alloc();
	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_CHAN_ACTIV);
	dh->chan_nr = gsm_lchan_as_pchan2chan_nr(lchan, GSM_PCHAN_PDCH);

	msgb_tv_put(msg, RSL_IE_ACT_TYPE, RSL_ACT_OSMO_PDCH);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/* Chapter 8.4.1 */
int rsl_chan_activate_lchan(struct gsm_lchan *lchan, uint8_t act_type,
			    uint8_t ho_ref)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg;
	int rc;
	uint8_t *len;
	uint8_t ta;

	struct rsl_ie_chan_mode cm;
	struct gsm48_chan_desc cd;

	/* If a TCH_F/PDCH TS is in PDCH mode, deactivate PDCH first. */
	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_PDCH
	    && (lchan->ts->flags & TS_F_PDCH_ACTIVE)) {
		/* store activation type and handover reference */
		lchan->dyn.act_type = act_type;
		lchan->dyn.ho_ref = ho_ref;
		return rsl_ipacc_pdch_activate(lchan->ts, 0);
	}

	/*
	 * If necessary, release PDCH on dynamic TS. Note that sending a
	 * release here is only necessary when in PDCH mode; for TCH types, an
	 * RSL RF Chan Release is initiated by the BTS when a voice call ends,
	 * so when we reach this, it will already be released. If a dyn TS is
	 * in PDCH mode, it is still active and we need to initiate a release
	 * from the BSC side here.
	 *
	 * If pchan_is != pchan_want, the PDCH has already been taken down and
	 * the switchover now needs to enable the TCH lchan.
	 *
	 * To switch a dyn TS between TCH/H and TCH/F, it is sufficient to send
	 * a chan activ with the new lchan type, because it will already be
	 * released.
	 */
	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH
	    && lchan->ts->dyn.pchan_is == GSM_PCHAN_PDCH
	    && lchan->ts->dyn.pchan_is == lchan->ts->dyn.pchan_want) {
		enum gsm_phys_chan_config pchan_want;
		pchan_want = pchan_for_lchant(lchan->type);
		if (lchan->ts->dyn.pchan_is != pchan_want) {
			/*
			 * Make sure to record on lchan[0] so that we'll find
			 * it after the PDCH release.
			 */
			struct gsm_lchan *lchan0 = lchan->ts->lchan;
			lchan0->dyn.act_type = act_type,
			lchan0->dyn.ho_ref = ho_ref;
			lchan0->dyn.rqd_ref = lchan->rqd_ref;
			lchan0->dyn.rqd_ta = lchan->rqd_ta;
			lchan->rqd_ref = NULL;
			lchan->rqd_ta = 0;
			DEBUGP(DRSL, "%s saved rqd_ref=%p ta=%u\n",
			       gsm_lchan_name(lchan0), lchan0->rqd_ref,
			       lchan0->rqd_ta);
			return dyn_ts_switchover_start(lchan->ts, pchan_want);
		}
	}

	DEBUGP(DRSL, "%s Tx RSL Channel Activate with act_type=%s\n",
	       gsm_ts_and_pchan_name(lchan->ts),
	       rsl_act_type_name(act_type));

	if (act_type == RSL_ACT_OSMO_PDCH) {
		if (lchan->ts->pchan != GSM_PCHAN_TCH_F_TCH_H_PDCH) {
			LOGP(DRSL, LOGL_ERROR,
			     "%s PDCH channel activation only allowed on %s\n",
			     gsm_ts_and_pchan_name(lchan->ts),
			     gsm_pchan_name(GSM_PCHAN_TCH_F_TCH_H_PDCH));
			return -EINVAL;
		}
		return rsl_chan_activate_lchan_as_pdch(lchan);
	}

	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH
	    && lchan->ts->dyn.pchan_want == GSM_PCHAN_PDCH) {
		LOGP(DRSL, LOGL_ERROR,
		     "%s Expected PDCH activation kind\n",
		     gsm_ts_and_pchan_name(lchan->ts));
		return -EINVAL;
	}

	rc = channel_mode_from_lchan(&cm, lchan);
	if (rc < 0) {
		LOGP(DRSL, LOGL_ERROR,
		     "%s Cannot find channel mode from lchan type\n",
		     gsm_ts_and_pchan_name(lchan->ts));
		return rc;
	}

	rsl_lchan_set_state(lchan, LCHAN_S_ACT_REQ);

	ta = lchan->rqd_ta;

	/* BS11 requires TA shifted by 2 bits */
	if (lchan->ts->trx->bts->type == GSM_BTS_TYPE_BS11)
		ta <<= 2;

	memset(&cd, 0, sizeof(cd));
	gsm48_lchan2chan_desc(&cd, lchan);

	msg = rsl_msgb_alloc();
	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_CHAN_ACTIV);

	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH)
		dh->chan_nr = gsm_lchan_as_pchan2chan_nr(
					lchan, lchan->ts->dyn.pchan_want);
	else
		dh->chan_nr = gsm_lchan2chan_nr(lchan);

	msgb_tv_put(msg, RSL_IE_ACT_TYPE, act_type);
	msgb_tlv_put(msg, RSL_IE_CHAN_MODE, sizeof(cm),
		     (uint8_t *) &cm);

	/*
	 * The Channel Identification is needed for Phase1 phones
	 * and it contains the GSM48 Channel Description and the
	 * Mobile Allocation. The GSM 08.58 asks for the Mobile
	 * Allocation to have a length of zero. We are using the
	 * msgb_l3len to calculate the length of both messages.
	 */
	msgb_v_put(msg, RSL_IE_CHAN_IDENT);
	len = msgb_put(msg, 1);
	msgb_tv_fixed_put(msg, GSM48_IE_CHANDESC_2, sizeof(cd), (const uint8_t *) &cd);

	if (lchan->ts->hopping.enabled)
		msgb_tlv_put(msg, GSM48_IE_MA_AFTER, lchan->ts->hopping.ma_len,
			     lchan->ts->hopping.ma_data);
	else
		msgb_tlv_put(msg, GSM48_IE_MA_AFTER, 0, NULL);

	/* update the calculated size */
	msg->l3h = len + 1;
	*len = msgb_l3len(msg);

	if (lchan->encr.alg_id > RSL_ENC_ALG_A5(0)) {
		uint8_t encr_info[MAX_A5_KEY_LEN+2];
		rc = build_encr_info(encr_info, lchan);
		if (rc > 0)
			msgb_tlv_put(msg, RSL_IE_ENCR_INFO, rc, encr_info);
	}

	switch (act_type) {
	case RSL_ACT_INTER_ASYNC:
	case RSL_ACT_INTER_SYNC:
		msgb_tv_put(msg, RSL_IE_HANDO_REF, ho_ref);
		break;
	default:
		break;
	}

	msgb_tv_put(msg, RSL_IE_BS_POWER, lchan->bs_power);
	msgb_tv_put(msg, RSL_IE_MS_POWER, lchan->ms_power);
	msgb_tv_put(msg, RSL_IE_TIMING_ADVANCE, ta);
	mr_config_for_bts(lchan, msg);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/* Chapter 8.4.9: Modify channel mode on BTS side */
int rsl_chan_mode_modify_req(struct gsm_lchan *lchan)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg;
	int rc;

	uint8_t chan_nr = gsm_lchan2chan_nr(lchan);
	struct rsl_ie_chan_mode cm;

	rc = channel_mode_from_lchan(&cm, lchan);
	if (rc < 0)
		return rc;

	msg = rsl_msgb_alloc();
	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_MODE_MODIFY_REQ);
	dh->chan_nr = chan_nr;

	msgb_tlv_put(msg, RSL_IE_CHAN_MODE, sizeof(cm),
		     (uint8_t *) &cm);

	if (lchan->encr.alg_id > RSL_ENC_ALG_A5(0)) {
		uint8_t encr_info[MAX_A5_KEY_LEN+2];
		rc = build_encr_info(encr_info, lchan);
		if (rc > 0)
			msgb_tlv_put(msg, RSL_IE_ENCR_INFO, rc, encr_info);
	}

	mr_config_for_bts(lchan, msg);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/* Chapter 8.4.6: Send the encryption command with given L3 info */
int rsl_encryption_cmd(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *dh;
	struct gsm_lchan *lchan = msg->lchan;
	uint8_t chan_nr = gsm_lchan2chan_nr(lchan);
	uint8_t encr_info[MAX_A5_KEY_LEN+2];
	uint8_t l3_len = msg->len;
	int rc;

	/* First push the L3 IE tag and length */
	msgb_tv16_push(msg, RSL_IE_L3_INFO, l3_len);

	/* then the link identifier (SAPI0, main sign link) */
	msgb_tv_push(msg, RSL_IE_LINK_IDENT, 0);

	/* then encryption information */
	rc = build_encr_info(encr_info, lchan);
	if (rc <= 0)
		return rc;
	msgb_tlv_push(msg, RSL_IE_ENCR_INFO, rc, encr_info);

	/* and finally the DCHAN header */
	dh = (struct abis_rsl_dchan_hdr *) msgb_push(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_ENCR_CMD);
	dh->chan_nr = chan_nr;

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/* Chapter 8.4.5 / 4.6: Deactivate the SACCH after 04.08 RR CHAN RELEASE */
int rsl_deact_sacch(struct gsm_lchan *lchan)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg = rsl_msgb_alloc();

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_DEACTIVATE_SACCH);
	dh->chan_nr = gsm_lchan2chan_nr(lchan);

	msg->lchan = lchan;
	msg->dst = lchan->ts->trx->rsl_link;

	DEBUGP(DRSL, "%s DEACTivate SACCH CMD\n", gsm_lchan_name(lchan));

	return abis_rsl_sendmsg(msg);
}

static bool dyn_ts_should_switch_to_pdch(struct gsm_bts_trx_ts *ts)
{
	int ss;

	if (ts->pchan != GSM_PCHAN_TCH_F_TCH_H_PDCH)
		return false;

	if (ts->trx->bts->gprs.mode == BTS_GPRS_NONE)
		return false;

	/* Already in PDCH mode? */
	if (ts->dyn.pchan_is == GSM_PCHAN_PDCH)
		return false;

	/* See if all lchans are released. */
	for (ss = 0; ss < ts_subslots(ts); ss++) {
		struct gsm_lchan *lc = &ts->lchan[ss];
		if (lc->state != LCHAN_S_NONE) {
			DEBUGP(DRSL, "%s lchan %u still in use"
			       " (type=%s,state=%s)\n",
			       gsm_ts_and_pchan_name(ts), lc->nr,
			       gsm_lchant_name(lc->type),
			       gsm_lchans_name(lc->state));
			/* An lchan is still used. */
			return false;
		}
	}

	/* All channels are released, go to PDCH mode. */
	DEBUGP(DRSL, "%s back to PDCH\n",
	       gsm_ts_and_pchan_name(ts));
	return true;
}

static void error_timeout_cb(void *data)
{
	struct gsm_lchan *lchan = data;
	if (lchan->state != LCHAN_S_REL_ERR) {
		LOGP(DRSL, LOGL_ERROR, "%s error timeout but not in error state: %d\n",
		     gsm_lchan_name(lchan), lchan->state);
		return;
	}

	/* go back to the none state */
	LOGP(DRSL, LOGL_INFO, "%s is back in operation.\n", gsm_lchan_name(lchan));
	rsl_lchan_set_state(lchan, LCHAN_S_NONE);

	/* Put PDCH channel back into PDCH mode, if GPRS is enabled */
	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_PDCH
	    && lchan->ts->trx->bts->gprs.mode != BTS_GPRS_NONE)
		rsl_ipacc_pdch_activate(lchan->ts, 1);

	if (dyn_ts_should_switch_to_pdch(lchan->ts))
		dyn_ts_switchover_start(lchan->ts, GSM_PCHAN_PDCH);
}

static int rsl_rx_rf_chan_rel_ack(struct gsm_lchan *lchan);

/* Chapter 8.4.14 / 4.7: Tell BTS to release the radio channel */
static int rsl_rf_chan_release(struct gsm_lchan *lchan, int error,
				enum sacch_deact deact_sacch)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg;
	int rc;

	/* Stop timers that should lead to a channel release */
	osmo_timer_del(&lchan->T3109);

	if (lchan->state == LCHAN_S_REL_ERR) {
		LOGP(DRSL, LOGL_NOTICE, "%s is in error state, not sending release.\n",
		     gsm_lchan_name(lchan));
		return -1;
	}

	msg = rsl_msgb_alloc();
	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_RF_CHAN_REL);
	dh->chan_nr = gsm_lchan2chan_nr(lchan);

	msg->lchan = lchan;
	msg->dst = lchan->ts->trx->rsl_link;

	if (error)
		DEBUGP(DRSL, "%s RF Channel Release due to error: %d\n",
		       gsm_lchan_name(lchan), error);
	else
		DEBUGP(DRSL, "%s RF Channel Release\n", gsm_lchan_name(lchan));

	if (error) {
		/*
		 * FIXME: GSM 04.08 gives us two options for the abnormal
		 * chanel release. This can be either like in the non-existent
		 * sub-lcuase 3.5.1 or for the main signalling link deactivate
		 * the SACCH, start timer T3109 and consider the channel as
		 * released.
		 *
		 * This code is doing the later for all raido links and not
		 * only the main link. Right now all SAPIs are released on the
		 * local end, the SACCH will be de-activated and right now the
		 * T3111 will be started. First T3109 should be started and then
		 * the T3111.
		 *
		 * TODO: Move this out of the function.
		 */

		/*
		 * sacch de-activate and "local end release"
		 */
		if (deact_sacch == SACCH_DEACTIVATE)
			rsl_deact_sacch(lchan);
		rsl_release_sapis_from(lchan, 0, RSL_REL_LOCAL_END);

		/*
		 * TODO: start T3109 now.
		 */
		rsl_lchan_set_state(lchan, LCHAN_S_REL_ERR);
	}

	/* Start another timer or assume the BTS sends a ACK/NACK? */
	lchan->act_timer.cb = lchan_deact_tmr_cb;
	lchan->act_timer.data = lchan;
	osmo_timer_schedule(&lchan->act_timer, 4, 0);

	rc =  abis_rsl_sendmsg(msg);

	/* BTS will respond by RF CHAN REL ACK */
	return rc;
}

/*
 * Special handling for channel releases in the error case.
 */
static int rsl_rf_chan_release_err(struct gsm_lchan *lchan)
{
	if (lchan->state != LCHAN_S_ACTIVE)
		return 0;
	return rsl_rf_chan_release(lchan, 1, SACCH_DEACTIVATE);
}

static int rsl_rx_rf_chan_rel_ack(struct gsm_lchan *lchan)
{
	struct gsm_bts_trx_ts *ts = lchan->ts;

	DEBUGP(DRSL, "%s RF CHANNEL RELEASE ACK\n", gsm_lchan_name(lchan));

	/* Stop all pending timers */
	osmo_timer_del(&lchan->act_timer);
	osmo_timer_del(&lchan->T3111);

	/*
	 * The BTS didn't respond within the timeout to our channel
	 * release request and we have marked the channel as broken.
	 * Now we do receive an ACK and let's be conservative. If it
	 * is a sysmoBTS we know that only one RF Channel Release ACK
	 * will be sent. So let's "repair" the channel.
	 */
	if (lchan->state == LCHAN_S_BROKEN) {
		int do_free = is_sysmobts_v2(ts->trx->bts);
		LOGP(DRSL, LOGL_NOTICE,
			"%s CHAN REL ACK for broken channel. %s.\n",
			gsm_lchan_name(lchan),
			do_free ? "Releasing it" : "Keeping it broken");
		if (do_free)
			do_lchan_free(lchan);
		if (dyn_ts_should_switch_to_pdch(lchan->ts))
			dyn_ts_switchover_start(lchan->ts, GSM_PCHAN_PDCH);
		return 0;
	}

	if (lchan->state != LCHAN_S_REL_REQ && lchan->state != LCHAN_S_REL_ERR)
		LOGP(DRSL, LOGL_NOTICE, "%s CHAN REL ACK but state %s\n",
			gsm_lchan_name(lchan),
			gsm_lchans_name(lchan->state));

	do_lchan_free(lchan);

	/*
	 * Check Osmocom RSL CHAN ACT style dynamic TCH/F_TCH/H_PDCH TS for pending
	 * transitions in these cases:
	 *
	 * a) after PDCH was released due to switchover request, activate TCH.
	 *    BSC initiated this switchover, so dyn.pchan_is != pchan_want and
	 *    lchan->type has been set to the desired GSM_LCHAN_*.
	 *
	 * b) Voice call ended and a TCH is released. If the TS is now unused,
	 *    switch to PDCH. Here still dyn.pchan_is == dyn.pchan_want because
	 *    we're only just notified and may decide to switch to PDCH now.
	 */
	if (ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH) {
		DEBUGP(DRSL, "%s Rx RSL Channel Release ack for lchan %u\n",
		       gsm_ts_and_pchan_name(ts), lchan->nr);

		/* (a) */
		if (ts->dyn.pchan_is != ts->dyn.pchan_want)
			return dyn_ts_switchover_continue(ts);
		
		/* (b) */
		if (dyn_ts_should_switch_to_pdch(ts))
			return dyn_ts_switchover_start(ts, GSM_PCHAN_PDCH);
	}

	/*
	 * Put a dynamic TCH/F_PDCH channel back to PDCH mode iff it was
	 * released successfully. If in error, the PDCH ACT will follow after
	 * T3111 in error_timeout_cb().
	 *
	 * Any state other than LCHAN_S_REL_ERR became LCHAN_S_NONE after above
	 * do_lchan_free(). Assert this, because that's what ensures a PDCH ACT
	 * on a TCH/F_PDCH TS in all cases.
	 *
	 * If GPRS is disabled, always skip the PDCH ACT.
	 */
	OSMO_ASSERT(lchan->state == LCHAN_S_NONE
		    || lchan->state == LCHAN_S_REL_ERR);
	if (ts->trx->bts->gprs.mode == BTS_GPRS_NONE)
		return 0;
	if (ts->pchan == GSM_PCHAN_TCH_F_PDCH
	    && lchan->state == LCHAN_S_NONE)
		return rsl_ipacc_pdch_activate(ts, 1);
	return 0;
}

int rsl_paging_cmd(struct gsm_bts *bts, uint8_t paging_group, uint8_t len,
		   uint8_t *ms_ident, uint8_t chan_needed)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *msg = rsl_msgb_alloc();

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_PAGING_CMD);
	dh->chan_nr = RSL_CHAN_PCH_AGCH;

	msgb_tv_put(msg, RSL_IE_PAGING_GROUP, paging_group);
	msgb_tlv_put(msg, RSL_IE_MS_IDENTITY, len-2, ms_ident+2);
	msgb_tv_put(msg, RSL_IE_CHAN_NEEDED, chan_needed);

	msg->dst = bts->c0->rsl_link;

	return abis_rsl_sendmsg(msg);
}

int imsi_str2bcd(uint8_t *bcd_out, const char *str_in)
{
	int i, len = strlen(str_in);

	for (i = 0; i < len; i++) {
		int num = str_in[i] - 0x30;
		if (num < 0 || num > 9)
			return -1;
		if (i % 2 == 0)
			bcd_out[i/2] = num;
		else
			bcd_out[i/2] |= (num << 4);
	}

	return 0;
}

/* Chapter 8.5.6 */
int rsl_imm_assign_cmd(struct gsm_bts *bts, uint8_t len, uint8_t *val)
{
	struct msgb *msg = rsl_msgb_alloc();
	struct abis_rsl_dchan_hdr *dh;
	uint8_t buf[MACBLOCK_SIZE];

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_IMMEDIATE_ASSIGN_CMD);
	dh->chan_nr = RSL_CHAN_PCH_AGCH;

	switch (bts->type) {
	case GSM_BTS_TYPE_BS11:
		msgb_tlv_put(msg, RSL_IE_IMM_ASS_INFO, len, val);
		break;
	default:
		/* If phase 2, construct a FULL_IMM_ASS_INFO */
		pad_macblock(buf, val, len);
		msgb_tlv_put(msg, RSL_IE_FULL_IMM_ASS_INFO, MACBLOCK_SIZE, buf);
		break;
	}

	msg->dst = bts->c0->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/* Send Siemens specific MS RF Power Capability Indication */
int rsl_siemens_mrpci(struct gsm_lchan *lchan, struct rsl_mrpci *mrpci)
{
	struct msgb *msg = rsl_msgb_alloc();
	struct abis_rsl_dchan_hdr *dh;

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_SIEMENS_MRPCI);
	dh->c.msg_discr = ABIS_RSL_MDISC_DED_CHAN;
	dh->chan_nr = gsm_lchan2chan_nr(lchan);
	msgb_tv_put(msg, RSL_IE_SIEMENS_MRPCI, *(uint8_t *)mrpci);

	DEBUGP(DRSL, "%s TX Siemens MRPCI 0x%02x\n",
		gsm_lchan_name(lchan), *(uint8_t *)mrpci);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}


/* Send "DATA REQUEST" message with given L3 Info payload */
/* Chapter 8.3.1 */
int rsl_data_request(struct msgb *msg, uint8_t link_id)
{
	if (msg->lchan == NULL) {
		LOGP(DRSL, LOGL_ERROR, "cannot send DATA REQUEST to unknown lchan\n");
		return -EINVAL;
	}

	rsl_rll_push_l3(msg, RSL_MT_DATA_REQ, gsm_lchan2chan_nr(msg->lchan),
			link_id, 1);

	msg->dst = msg->lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/* Send "ESTABLISH REQUEST" message with given L3 Info payload */
/* Chapter 8.3.1 */
int rsl_establish_request(struct gsm_lchan *lchan, uint8_t link_id)
{
	struct msgb *msg;

	msg = rsl_rll_simple(RSL_MT_EST_REQ, gsm_lchan2chan_nr(lchan),
			     link_id, 0);
	msg->dst = lchan->ts->trx->rsl_link;

	DEBUGP(DRLL, "%s RSL RLL ESTABLISH REQ (link_id=0x%02x)\n",
		gsm_lchan_name(lchan), link_id);

	return abis_rsl_sendmsg(msg);
}

static void rsl_handle_release(struct gsm_lchan *lchan);

/* Special work handler to handle missing RSL_MT_REL_CONF message from
 * Nokia InSite BTS */
static void lchan_rel_work_cb(void *data)
{
	struct gsm_lchan *lchan = data;
	int sapi;

	for (sapi = 0; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
		if (lchan->sapis[sapi] == LCHAN_SAPI_REL)
			lchan->sapis[sapi] = LCHAN_SAPI_UNUSED;
	}
	rsl_handle_release(lchan);
}

/* Chapter 8.3.7 Request the release of multiframe mode of RLL connection.
   This is what higher layers should call.  The BTS then responds with
   RELEASE CONFIRM, which we in turn use to trigger RSL CHANNEL RELEASE,
   which in turn is acknowledged by RSL CHANNEL RELEASE ACK, which calls
   lchan_free() */
int rsl_release_request(struct gsm_lchan *lchan, uint8_t link_id,
			enum rsl_rel_mode release_mode)
{

	struct msgb *msg;

	msg = rsl_rll_simple(RSL_MT_REL_REQ, gsm_lchan2chan_nr(lchan),
			     link_id, 0);
	/* 0 is normal release, 1 is local end */
	msgb_tv_put(msg, RSL_IE_RELEASE_MODE, release_mode);

	/* FIXME: start some timer in case we don't receive a REL ACK ? */

	msg->dst = lchan->ts->trx->rsl_link;

	DEBUGP(DRLL, "%s RSL RLL RELEASE REQ (link_id=0x%02x, reason=%u)\n",
		gsm_lchan_name(lchan), link_id, release_mode);

	abis_rsl_sendmsg(msg);

	/* Do not wait for Nokia BTS to send the confirm. */
	if (is_nokia_bts(lchan->ts->trx->bts)
	 && lchan->ts->trx->bts->nokia.no_loc_rel_cnf
	 && release_mode == RSL_REL_LOCAL_END) {
		DEBUGP(DRLL, "Scheduling release, becasuse Nokia InSite BTS does not send a RELease CONFirm.\n");
		lchan->sapis[link_id & 0x7] = LCHAN_SAPI_REL;
		lchan->rel_work.cb = lchan_rel_work_cb;
		lchan->rel_work.data = lchan;
		osmo_timer_schedule(&lchan->rel_work, 0, 0);
	}

	return 0;
}

int rsl_lchan_mark_broken(struct gsm_lchan *lchan, const char *reason)
{
	LOGP(DRSL, LOGL_ERROR, "%s %s lchan broken: %s\n",
	     gsm_lchan_name(lchan), gsm_lchant_name(lchan->type), reason);
	rsl_lchan_set_state(lchan, LCHAN_S_BROKEN);
	lchan->broken_reason = reason;
	return 0;
}

int rsl_lchan_set_state(struct gsm_lchan *lchan, int state)
{
	DEBUGP(DRSL, "%s state %s -> %s\n",
	       gsm_lchan_name(lchan), gsm_lchans_name(lchan->state),
	       gsm_lchans_name(state));
	lchan->state = state;
	return 0;
}

/* Chapter 8.4.2: Channel Activate Acknowledge */
static int rsl_rx_chan_act_ack(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *rslh = msgb_l2(msg);
	struct gsm_lchan *lchan = msg->lchan;
	struct gsm_bts_trx_ts *ts = lchan->ts;

	/* BTS has confirmed channel activation, we now need
	 * to assign the activated channel to the MS */
	if (rslh->ie_chan != RSL_IE_CHAN_NR)
		return -EINVAL;

	osmo_timer_del(&lchan->act_timer);

	if (lchan->state == LCHAN_S_BROKEN) {
		int do_release = is_sysmobts_v2(ts->trx->bts);
		LOGP(DRSL, LOGL_NOTICE, "%s CHAN ACT ACK for broken channel. %s\n",
			gsm_lchan_name(lchan),
			do_release ? "Releasing it" : "Keeping it broken");
		if (do_release) {
			talloc_free(lchan->rqd_ref);
			lchan->rqd_ref = NULL;
			lchan->rqd_ta = 0;
			rsl_lchan_set_state(msg->lchan, LCHAN_S_ACTIVE);
			if (ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH) {
				/*
				 * lchan_act_tmr_cb() already called
				 * lchan_free() and cleared the lchan->type, so
				 * calling dyn_ts_switchover_complete() here
				 * would not have the desired effect of
				 * mimicking an activated lchan that we can
				 * release. Instead hack the dyn ts state to
				 * make sure that rsl_rx_rf_chan_rel_ack() will
				 * switch back to PDCH, i.e. have pchan_is ==
				 * pchan_want, both != GSM_PCHAN_PDCH:
				 */
				ts->dyn.pchan_is = GSM_PCHAN_NONE;
				ts->dyn.pchan_want = GSM_PCHAN_NONE;
			}
			rsl_rf_chan_release(msg->lchan, 0, SACCH_NONE);
		}
		return 0;
	}

	if (lchan->state != LCHAN_S_ACT_REQ)
		LOGP(DRSL, LOGL_NOTICE, "%s CHAN ACT ACK, but state %s\n",
			gsm_lchan_name(lchan),
			gsm_lchans_name(lchan->state));
	rsl_lchan_set_state(lchan, LCHAN_S_ACTIVE);

	if (ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH)
		dyn_ts_switchover_complete(lchan);

	if (lchan->rqd_ref) {
		rsl_send_imm_assignment(lchan);
		talloc_free(lchan->rqd_ref);
		lchan->rqd_ref = NULL;
		lchan->rqd_ta = 0;
	}

	send_lchan_signal(S_LCHAN_ACTIVATE_ACK, lchan, NULL);

	return 0;
}

/* Chapter 8.4.3: Channel Activate NACK */
static int rsl_rx_chan_act_nack(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *dh = msgb_l2(msg);
	struct tlv_parsed tp;

	osmo_timer_del(&msg->lchan->act_timer);

	if (msg->lchan->state == LCHAN_S_BROKEN) {
		LOGP(DRSL, LOGL_ERROR,
			"%s CHANNEL ACTIVATE NACK for broken channel.\n",
			gsm_lchan_name(msg->lchan));
		return -1;
	}

	LOGP(DRSL, LOGL_ERROR, "%s CHANNEL ACTIVATE NACK ",
		gsm_lchan_name(msg->lchan));

	/* BTS has rejected channel activation ?!? */
	if (dh->ie_chan != RSL_IE_CHAN_NR)
		return -EINVAL;

	rsl_tlv_parse(&tp, dh->data, msgb_l2len(msg)-sizeof(*dh));
	if (TLVP_PRESENT(&tp, RSL_IE_CAUSE)) {
		const uint8_t *cause = TLVP_VAL(&tp, RSL_IE_CAUSE);
		print_rsl_cause(LOGL_ERROR, cause,
				TLVP_LEN(&tp, RSL_IE_CAUSE));
		msg->lchan->error_cause = *cause;
		if (*cause != RSL_ERR_RCH_ALR_ACTV_ALLOC) {
			rsl_lchan_mark_broken(msg->lchan, "NACK on activation");
		} else
			rsl_rf_chan_release(msg->lchan, 1, SACCH_DEACTIVATE);

	} else {
		rsl_lchan_mark_broken(msg->lchan, "NACK on activation no IE");
	}

	LOGPC(DRSL, LOGL_ERROR, "\n");

	send_lchan_signal(S_LCHAN_ACTIVATE_NACK, msg->lchan, NULL);
	return 0;
}

/* Chapter 8.4.4: Connection Failure Indication */
static int rsl_rx_conn_fail(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *dh = msgb_l2(msg);
	struct tlv_parsed tp;

	LOGP(DRSL, LOGL_NOTICE, "%s CONNECTION FAIL: RELEASING state %s ",
	     gsm_lchan_name(msg->lchan),
	     gsm_lchans_name(msg->lchan->state));

	rsl_tlv_parse(&tp, dh->data, msgb_l2len(msg)-sizeof(*dh));

	if (TLVP_PRESENT(&tp, RSL_IE_CAUSE))
		print_rsl_cause(LOGL_NOTICE, TLVP_VAL(&tp, RSL_IE_CAUSE),
				TLVP_LEN(&tp, RSL_IE_CAUSE));

	LOGPC(DRSL, LOGL_NOTICE, "\n");
	rate_ctr_inc(&msg->lchan->ts->trx->bts->network->bsc_ctrs->ctr[BSC_CTR_CHAN_RF_FAIL]);
	return rsl_rf_chan_release_err(msg->lchan);
}

static void print_meas_rep_uni(struct gsm_meas_rep_unidir *mru,
				const char *prefix)
{
	DEBUGPC(DMEAS, "RXL-FULL-%s=%3ddBm RXL-SUB-%s=%3ddBm ",
		prefix, rxlev2dbm(mru->full.rx_lev),
		prefix, rxlev2dbm(mru->sub.rx_lev));
	DEBUGPC(DMEAS, "RXQ-FULL-%s=%d RXQ-SUB-%s=%d ",
		prefix, mru->full.rx_qual, prefix, mru->sub.rx_qual);
}

static void print_meas_rep(struct gsm_lchan *lchan, struct gsm_meas_rep *mr)
{
	int i;
	char *name = "";

	if (lchan && lchan->conn)
		name = subscr_name(lchan->conn->subscr);

	DEBUGP(DMEAS, "[%s] MEASUREMENT RESULT NR=%d ", name, mr->nr);

	if (mr->flags & MEAS_REP_F_DL_DTX)
		DEBUGPC(DMEAS, "DTXd ");

	print_meas_rep_uni(&mr->ul, "ul");
	DEBUGPC(DMEAS, "BS_POWER=%d ", mr->bs_power);
	if (mr->flags & MEAS_REP_F_MS_TO)
		DEBUGPC(DMEAS, "MS_TO=%d ", mr->ms_timing_offset);

	if (mr->flags & MEAS_REP_F_MS_L1) {
		DEBUGPC(DMEAS, "L1_MS_PWR=%3ddBm ", mr->ms_l1.pwr);
		DEBUGPC(DMEAS, "L1_FPC=%u ",
			mr->flags & MEAS_REP_F_FPC ? 1 : 0);
		DEBUGPC(DMEAS, "L1_TA=%u ", mr->ms_l1.ta);
	}

	if (mr->flags & MEAS_REP_F_UL_DTX)
		DEBUGPC(DMEAS, "DTXu ");
	if (mr->flags & MEAS_REP_F_BA1)
		DEBUGPC(DMEAS, "BA1 ");
	if (!(mr->flags & MEAS_REP_F_DL_VALID))
		DEBUGPC(DMEAS, "NOT VALID ");
	else
		print_meas_rep_uni(&mr->dl, "dl");

	DEBUGPC(DMEAS, "NUM_NEIGH=%u\n", mr->num_cell);
	if (mr->num_cell == 7)
		return;
	for (i = 0; i < mr->num_cell; i++) {
		struct gsm_meas_rep_cell *mrc = &mr->cell[i];
		DEBUGP(DMEAS, "IDX=%u ARFCN=%u BSIC=%u => %d dBm\n",
			mrc->neigh_idx, mrc->arfcn, mrc->bsic, rxlev2dbm(mrc->rxlev));
	}
}

static int rsl_rx_meas_res(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *dh = msgb_l2(msg);
	struct tlv_parsed tp;
	struct gsm_meas_rep *mr = lchan_next_meas_rep(msg->lchan);
	uint8_t len;
	const uint8_t *val;
	int rc;

	/* check if this channel is actually active */
	/* FIXME: maybe this check should be way more generic/centralized */
	if (msg->lchan->state != LCHAN_S_ACTIVE) {
		LOGP(DRSL, LOGL_DEBUG, "%s: MEAS RES for inactive channel\n",
			gsm_lchan_name(msg->lchan));
		return 0;
	}

	memset(mr, 0, sizeof(*mr));
	mr->lchan = msg->lchan;

	rsl_tlv_parse(&tp, dh->data, msgb_l2len(msg)-sizeof(*dh));

	if (!TLVP_PRESENT(&tp, RSL_IE_MEAS_RES_NR) ||
	    !TLVP_PRESENT(&tp, RSL_IE_UPLINK_MEAS) ||
	    !TLVP_PRESENT(&tp, RSL_IE_BS_POWER))
		return -EIO;

	/* Mandatory Parts */
	mr->nr = *TLVP_VAL(&tp, RSL_IE_MEAS_RES_NR);

	len = TLVP_LEN(&tp, RSL_IE_UPLINK_MEAS);
	val = TLVP_VAL(&tp, RSL_IE_UPLINK_MEAS);
	if (len >= 3) {
		if (val[0] & 0x40)
			mr->flags |= MEAS_REP_F_DL_DTX;
		mr->ul.full.rx_lev = val[0] & 0x3f;
		mr->ul.sub.rx_lev = val[1] & 0x3f;
		mr->ul.full.rx_qual = val[2]>>3 & 0x7;
		mr->ul.sub.rx_qual = val[2] & 0x7;
	}

	mr->bs_power = *TLVP_VAL(&tp, RSL_IE_BS_POWER);

	/* Optional Parts */
	if (TLVP_PRESENT(&tp, RSL_IE_MS_TIMING_OFFSET))
		mr->ms_timing_offset =
			*TLVP_VAL(&tp, RSL_IE_MS_TIMING_OFFSET);

	if (TLVP_PRESENT(&tp, RSL_IE_L1_INFO)) {
		struct e1inp_sign_link *sign_link = msg->dst;

		val = TLVP_VAL(&tp, RSL_IE_L1_INFO);
		mr->flags |= MEAS_REP_F_MS_L1;
		mr->ms_l1.pwr = ms_pwr_dbm(sign_link->trx->bts->band, val[0] >> 3);
		if (val[0] & 0x04)
			mr->flags |= MEAS_REP_F_FPC;
		mr->ms_l1.ta = val[1];
		/* BS11 and Nokia reports TA shifted by 2 bits */
		if (msg->lchan->ts->trx->bts->type == GSM_BTS_TYPE_BS11
		 || msg->lchan->ts->trx->bts->type == GSM_BTS_TYPE_NOKIA_SITE)
			mr->ms_l1.ta >>= 2;
	}
	if (TLVP_PRESENT(&tp, RSL_IE_L3_INFO)) {
		msg->l3h = (uint8_t *) TLVP_VAL(&tp, RSL_IE_L3_INFO);
		rc = gsm48_parse_meas_rep(mr, msg);
		if (rc < 0)
			return rc;
	}

	print_meas_rep(msg->lchan, mr);

	send_lchan_signal(S_LCHAN_MEAS_REP, msg->lchan, mr);

	return 0;
}

/* Chapter 8.4.7 */
static int rsl_rx_hando_det(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *dh = msgb_l2(msg);
	struct tlv_parsed tp;

	DEBUGP(DRSL, "%s HANDOVER DETECT ", gsm_lchan_name(msg->lchan));

	rsl_tlv_parse(&tp, dh->data, msgb_l2len(msg)-sizeof(*dh));

	if (TLVP_PRESENT(&tp, RSL_IE_ACCESS_DELAY))
		DEBUGPC(DRSL, "access delay = %u\n",
			*TLVP_VAL(&tp, RSL_IE_ACCESS_DELAY));
	else
		DEBUGPC(DRSL, "\n");

	send_lchan_signal(S_LCHAN_HANDOVER_DETECT, msg->lchan, NULL);

	return 0;
}

static bool lchan_may_change_pdch(struct gsm_lchan *lchan, bool pdch_act)
{
	struct gsm_bts_trx_ts *ts;

	OSMO_ASSERT(lchan);

	ts = lchan->ts;
	OSMO_ASSERT(ts);
	OSMO_ASSERT(ts->trx);
	OSMO_ASSERT(ts->trx->bts);

	if (lchan->ts->pchan != GSM_PCHAN_TCH_F_PDCH) {
		LOGP(DRSL, LOGL_ERROR, "%s pchan=%s Rx PDCH %s ACK"
		     " for channel that is no TCH/F_PDCH\n",
		     gsm_lchan_name(lchan),
		     gsm_pchan_name(ts->pchan),
		     pdch_act? "ACT" : "DEACT");
		return false;
	}

	if (lchan->state != LCHAN_S_NONE) {
		LOGP(DRSL, LOGL_ERROR, "%s pchan=%s Rx PDCH %s ACK"
		     " in unexpected state: %s\n",
		     gsm_lchan_name(lchan),
		     gsm_pchan_name(ts->pchan),
		     pdch_act? "ACT" : "DEACT",
		     gsm_lchans_name(lchan->state));
		return false;
	}
	return true;
}

static int rsl_rx_pdch_act_ack(struct msgb *msg)
{
	if (!lchan_may_change_pdch(msg->lchan, true))
		return -EINVAL;

	msg->lchan->ts->flags |= TS_F_PDCH_ACTIVE;
	msg->lchan->ts->flags &= ~TS_F_PDCH_ACT_PENDING;

	return 0;
}

static int rsl_rx_pdch_deact_ack(struct msgb *msg)
{
	if (!lchan_may_change_pdch(msg->lchan, false))
		return -EINVAL;

	msg->lchan->ts->flags &= ~TS_F_PDCH_ACTIVE;
	msg->lchan->ts->flags &= ~TS_F_PDCH_DEACT_PENDING;

	rsl_chan_activate_lchan(msg->lchan, msg->lchan->dyn.act_type,
				msg->lchan->dyn.ho_ref);

	return 0;
}

static int abis_rsl_rx_dchan(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *rslh = msgb_l2(msg);
	int rc = 0;
	char *ts_name;
	struct e1inp_sign_link *sign_link = msg->dst;

	msg->lchan = lchan_lookup(sign_link->trx, rslh->chan_nr,
				  "Abis RSL rx DCHAN: ");
	if (!msg->lchan)
		return -1;
	ts_name = gsm_lchan_name(msg->lchan);

	switch (rslh->c.msg_type) {
	case RSL_MT_CHAN_ACTIV_ACK:
		DEBUGP(DRSL, "%s CHANNEL ACTIVATE ACK\n", ts_name);
		rc = rsl_rx_chan_act_ack(msg);
		count_codecs(sign_link->trx->bts, msg->lchan);
		break;
	case RSL_MT_CHAN_ACTIV_NACK:
		rc = rsl_rx_chan_act_nack(msg);
		break;
	case RSL_MT_CONN_FAIL:
		rc = rsl_rx_conn_fail(msg);
		break;
	case RSL_MT_MEAS_RES:
		rc = rsl_rx_meas_res(msg);
		break;
	case RSL_MT_HANDO_DET:
		rc = rsl_rx_hando_det(msg);
		break;
	case RSL_MT_RF_CHAN_REL_ACK:
		rc = rsl_rx_rf_chan_rel_ack(msg->lchan);
		break;
	case RSL_MT_MODE_MODIFY_ACK:
		count_codecs(sign_link->trx->bts, msg->lchan);
		DEBUGP(DRSL, "%s CHANNEL MODE MODIFY ACK\n", ts_name);
		break;
	case RSL_MT_MODE_MODIFY_NACK:
		LOGP(DRSL, LOGL_ERROR, "%s CHANNEL MODE MODIFY NACK\n", ts_name);
		break;
	case RSL_MT_IPAC_PDCH_ACT_ACK:
		DEBUGP(DRSL, "%s IPAC PDCH ACT ACK\n", ts_name);
		rc = rsl_rx_pdch_act_ack(msg);
		break;
	case RSL_MT_IPAC_PDCH_ACT_NACK:
		LOGP(DRSL, LOGL_ERROR, "%s IPAC PDCH ACT NACK\n", ts_name);
		break;
	case RSL_MT_IPAC_PDCH_DEACT_ACK:
		DEBUGP(DRSL, "%s IPAC PDCH DEACT ACK\n", ts_name);
		rc = rsl_rx_pdch_deact_ack(msg);
		break;
	case RSL_MT_IPAC_PDCH_DEACT_NACK:
		LOGP(DRSL, LOGL_ERROR, "%s IPAC PDCH DEACT NACK\n", ts_name);
		break;
	case RSL_MT_PHY_CONTEXT_CONF:
	case RSL_MT_PREPROC_MEAS_RES:
	case RSL_MT_TALKER_DET:
	case RSL_MT_LISTENER_DET:
	case RSL_MT_REMOTE_CODEC_CONF_REP:
	case RSL_MT_MR_CODEC_MOD_ACK:
	case RSL_MT_MR_CODEC_MOD_NACK:
	case RSL_MT_MR_CODEC_MOD_PER:
		LOGP(DRSL, LOGL_NOTICE, "%s Unimplemented Abis RSL DChan "
			"msg 0x%02x\n", ts_name, rslh->c.msg_type);
		break;
	default:
		LOGP(DRSL, LOGL_NOTICE, "%s unknown Abis RSL DChan msg 0x%02x\n",
			ts_name, rslh->c.msg_type);
		return -EINVAL;
	}

	return rc;
}

static int rsl_rx_error_rep(struct msgb *msg)
{
	struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
	struct tlv_parsed tp;
	struct e1inp_sign_link *sign_link = msg->dst;

	LOGP(DRSL, LOGL_ERROR, "%s ERROR REPORT ", gsm_trx_name(sign_link->trx));

	rsl_tlv_parse(&tp, rslh->data, msgb_l2len(msg)-sizeof(*rslh));

	if (TLVP_PRESENT(&tp, RSL_IE_CAUSE))
		print_rsl_cause(LOGL_ERROR, TLVP_VAL(&tp, RSL_IE_CAUSE),
				TLVP_LEN(&tp, RSL_IE_CAUSE));

	LOGPC(DRSL, LOGL_ERROR, "\n");

	return 0;
}

static int abis_rsl_rx_trx(struct msgb *msg)
{
	struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
	struct e1inp_sign_link *sign_link = msg->dst;
	int rc = 0;

	switch (rslh->msg_type) {
	case RSL_MT_ERROR_REPORT:
		rc = rsl_rx_error_rep(msg);
		break;
	case RSL_MT_RF_RES_IND:
		/* interference on idle channels of TRX */
		//DEBUGP(DRSL, "%s RF Resource Indication\n", gsm_trx_name(sign_link->trx));
		break;
	case RSL_MT_OVERLOAD:
		/* indicate CCCH / ACCH / processor overload */
		LOGP(DRSL, LOGL_ERROR, "%s CCCH/ACCH/CPU Overload\n",
		     gsm_trx_name(sign_link->trx));
		break;
	case 0x42: /* Nokia specific: SI End ACK */
		LOGP(DRSL, LOGL_INFO, "Nokia SI End ACK\n");
		break;
	case 0x43: /* Nokia specific: SI End NACK */
		LOGP(DRSL, LOGL_INFO, "Nokia SI End NACK\n");
		break;
	default:
		LOGP(DRSL, LOGL_NOTICE, "%s Unknown Abis RSL TRX message "
			"type 0x%02x\n", gsm_trx_name(sign_link->trx), rslh->msg_type);
		return -EINVAL;
	}
	return rc;
}

/* If T3101 expires, we never received a response to IMMEDIATE ASSIGN */
static void t3101_expired(void *data)
{
	struct gsm_lchan *lchan = data;

	rsl_rf_chan_release(lchan, 1, SACCH_DEACTIVATE);
}

/* If T3111 expires, we will send the RF Channel Request */
static void t3111_expired(void *data)
{
	struct gsm_lchan *lchan = data;

	rsl_rf_chan_release(lchan, 0, SACCH_NONE);
}

/* If T3109 expires the MS has not send a UA/UM do the error release */
static void t3109_expired(void *data)
{
	struct gsm_lchan *lchan = data;

	LOGP(DRSL, LOGL_ERROR,
		"%s SACCH deactivation timeout.\n", gsm_lchan_name(lchan));
	rsl_rf_chan_release(lchan, 1, SACCH_NONE);
}

/* Format an IMM ASS REJ according to 04.08 Chapter 9.1.20 */
static int rsl_send_imm_ass_rej(struct gsm_bts *bts,
				unsigned int num_req_refs,
				struct gsm48_req_ref *rqd_refs,
				uint8_t wait_ind)
{
	uint8_t buf[GSM_MACBLOCK_LEN];
	struct gsm48_imm_ass_rej *iar = (struct gsm48_imm_ass_rej *)buf;

	/* create IMMEDIATE ASSIGN REJECT 04.08 message */
	memset(iar, 0, sizeof(*iar));
	iar->proto_discr = GSM48_PDISC_RR;
	iar->msg_type = GSM48_MT_RR_IMM_ASS_REJ;
	iar->page_mode = GSM48_PM_SAME;

	memcpy(&iar->req_ref1, &rqd_refs[0], sizeof(iar->req_ref1));
	iar->wait_ind1 = wait_ind;

	if (num_req_refs >= 2)
		memcpy(&iar->req_ref2, &rqd_refs[1], sizeof(iar->req_ref2));
	else
		memcpy(&iar->req_ref2, &rqd_refs[0], sizeof(iar->req_ref2));
	iar->wait_ind2 = wait_ind;

	if (num_req_refs >= 3)
		memcpy(&iar->req_ref3, &rqd_refs[2], sizeof(iar->req_ref3));
	else
		memcpy(&iar->req_ref3, &rqd_refs[0], sizeof(iar->req_ref3));
	iar->wait_ind3 = wait_ind;

	if (num_req_refs >= 4)
		memcpy(&iar->req_ref4, &rqd_refs[3], sizeof(iar->req_ref4));
	else
		memcpy(&iar->req_ref4, &rqd_refs[0], sizeof(iar->req_ref4));
	iar->wait_ind4 = wait_ind;

	/* we need to subtract 1 byte from sizeof(*iar) since ia includes the l2_plen field */
	iar->l2_plen = GSM48_LEN2PLEN((sizeof(*iar)-1));

	return rsl_imm_assign_cmd(bts, sizeof(*iar), (uint8_t *) iar);
}

/* MS has requested a channel on the RACH */
static int rsl_rx_chan_rqd(struct msgb *msg)
{
	struct e1inp_sign_link *sign_link = msg->dst;
	struct gsm_bts *bts = sign_link->trx->bts;
	struct abis_rsl_dchan_hdr *rqd_hdr = msgb_l2(msg);
	struct gsm48_req_ref *rqd_ref;
	enum gsm_chan_t lctype;
	enum gsm_chreq_reason_t chreq_reason;
	struct gsm_lchan *lchan;
	uint8_t rqd_ta;
	int is_lu;

	uint16_t arfcn;
	uint8_t subch;

	/* parse request reference to be used in immediate assign */
	if (rqd_hdr->data[0] != RSL_IE_REQ_REFERENCE)
		return -EINVAL;

	rqd_ref = (struct gsm48_req_ref *) &rqd_hdr->data[1];

	/* parse access delay and use as TA */
	if (rqd_hdr->data[sizeof(struct gsm48_req_ref)+1] != RSL_IE_ACCESS_DELAY)
		return -EINVAL;
	rqd_ta = rqd_hdr->data[sizeof(struct gsm48_req_ref)+2];

	/* determine channel type (SDCCH/TCH_F/TCH_H) based on
	 * request reference RA */
	lctype = get_ctype_by_chreq(bts->network, rqd_ref->ra);
	chreq_reason = get_reason_by_chreq(rqd_ref->ra, bts->network->neci);

	rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_CHREQ_TOTAL]);

	/*
	 * We want LOCATION UPDATES to succeed and will assign a TCH
	 * if we have no SDCCH available.
	 */
	is_lu = !!(chreq_reason == GSM_CHREQ_REASON_LOCATION_UPD);

	/* check availability / allocate channel */
	lchan = lchan_alloc(bts, lctype, is_lu);
	if (!lchan) {
		LOGP(DRSL, LOGL_NOTICE, "BTS %d CHAN RQD: no resources for %s 0x%x\n",
		     msg->lchan->ts->trx->bts->nr, gsm_lchant_name(lctype), rqd_ref->ra);
		rate_ctr_inc(&bts->network->bsc_ctrs->ctr[BSC_CTR_CHREQ_NO_CHANNEL]);
		/* FIXME gather multiple CHAN RQD and reject up to 4 at the same time */
		if (bts->network->T3122)
			rsl_send_imm_ass_rej(bts, 1, rqd_ref, bts->network->T3122 & 0xff);
		return 0;
	}

	/*
	 * Expecting lchan state to be NONE, except for dyn TS in PDCH mode.
	 * Those are expected to be ACTIVE: the PDCH release will be sent from
	 * rsl_chan_activate_lchan() below.
	 */
	if (lchan->state != LCHAN_S_NONE
	    && !(lchan->ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH
		 && lchan->ts->dyn.pchan_is == GSM_PCHAN_PDCH
		 && lchan->state == LCHAN_S_ACTIVE))
		LOGP(DRSL, LOGL_NOTICE, "%s lchan_alloc() returned channel "
		     "in state %s\n", gsm_lchan_name(lchan),
		     gsm_lchans_name(lchan->state));

	/* save the RACH data as we need it after the CHAN ACT ACK */
	lchan->rqd_ref = talloc_zero(bts, struct gsm48_req_ref);
	if (!lchan->rqd_ref) {
		LOGP(DRSL, LOGL_ERROR, "Failed to allocate gsm48_req_ref.\n");
		lchan_free(lchan);
		return -ENOMEM;
	}

	memcpy(lchan->rqd_ref, rqd_ref, sizeof(*rqd_ref));
	lchan->rqd_ta = rqd_ta;

	arfcn = lchan->ts->trx->arfcn;
	subch = lchan->nr;
	
	lchan->encr.alg_id = RSL_ENC_ALG_A5(0);	/* no encryption */
	lchan->ms_power = ms_pwr_ctl_lvl(bts->band, bts->ms_max_power);
	lchan->bs_power = 0; /* 0dB reduction, output power = Pn */
	lchan->rsl_cmode = RSL_CMOD_SPD_SIGN;
	lchan->tch_mode = GSM48_CMODE_SIGN;

	/* Start another timer or assume the BTS sends a ACK/NACK? */
	lchan->act_timer.cb = lchan_act_tmr_cb;
	lchan->act_timer.data = lchan;
	osmo_timer_schedule(&lchan->act_timer, 4, 0);

	DEBUGP(DRSL, "%s Activating ARFCN(%u) SS(%u) lctype %s "
		"r=%s ra=0x%02x ta=%d\n", gsm_lchan_name(lchan), arfcn, subch,
		gsm_lchant_name(lchan->type), gsm_chreq_name(chreq_reason),
		rqd_ref->ra, rqd_ta);

	rsl_chan_activate_lchan(lchan, RSL_ACT_INTRA_IMM_ASS, 0);

	return 0;
}

static int rsl_send_imm_assignment(struct gsm_lchan *lchan)
{
	struct gsm_bts *bts = lchan->ts->trx->bts;
	uint8_t buf[GSM_MACBLOCK_LEN];
	struct gsm48_imm_ass *ia = (struct gsm48_imm_ass *) buf;

	/* create IMMEDIATE ASSIGN 04.08 messge */
	memset(ia, 0, sizeof(*ia));
	/* we set ia->l2_plen once we know the length of the MA below */
	ia->proto_discr = GSM48_PDISC_RR;
	ia->msg_type = GSM48_MT_RR_IMM_ASS;
	ia->page_mode = GSM48_PM_SAME;
	gsm48_lchan2chan_desc(&ia->chan_desc, lchan);

	/* use request reference extracted from CHAN_RQD */
	memcpy(&ia->req_ref, lchan->rqd_ref, sizeof(ia->req_ref));
	ia->timing_advance = lchan->rqd_ta;
	if (!lchan->ts->hopping.enabled) {
		ia->mob_alloc_len = 0;
	} else {
		ia->mob_alloc_len = lchan->ts->hopping.ma_len;
		memcpy(ia->mob_alloc, lchan->ts->hopping.ma_data, ia->mob_alloc_len);
	}
	/* we need to subtract 1 byte from sizeof(*ia) since ia includes the l2_plen field */
	ia->l2_plen = GSM48_LEN2PLEN((sizeof(*ia)-1) + ia->mob_alloc_len);

	/* Start timer T3101 to wait for GSM48_MT_RR_PAG_RESP */
	lchan->T3101.cb = t3101_expired;
	lchan->T3101.data = lchan;
	osmo_timer_schedule(&lchan->T3101, bts->network->T3101, 0);

	/* send IMMEDIATE ASSIGN CMD on RSL to BTS (to send on CCCH to MS) */
	return rsl_imm_assign_cmd(bts, sizeof(*ia)+ia->mob_alloc_len, (uint8_t *) ia);
}

/* current load on the CCCH */
static int rsl_rx_ccch_load(struct msgb *msg)
{
	struct e1inp_sign_link *sign_link = msg->dst;
	struct abis_rsl_dchan_hdr *rslh = msgb_l2(msg);
	struct ccch_signal_data sd;

	sd.bts = sign_link->trx->bts;
	sd.rach_slot_count = -1;
	sd.rach_busy_count = -1;
	sd.rach_access_count = -1;

	switch (rslh->data[0]) {
	case RSL_IE_PAGING_LOAD:
		sd.pg_buf_space = rslh->data[1] << 8 | rslh->data[2];
		if (is_ipaccess_bts(sign_link->trx->bts) && sd.pg_buf_space == 0xffff) {
			/* paging load below configured threshold, use 50 as default */
			sd.pg_buf_space = 50;
		}
		paging_update_buffer_space(sign_link->trx->bts, sd.pg_buf_space);
		osmo_signal_dispatch(SS_CCCH, S_CCCH_PAGING_LOAD, &sd);
		break;
	case RSL_IE_RACH_LOAD:
		if (msg->data_len >= 7) {
			sd.rach_slot_count = rslh->data[2] << 8 | rslh->data[3];
			sd.rach_busy_count = rslh->data[4] << 8 | rslh->data[5];
			sd.rach_access_count = rslh->data[6] << 8 | rslh->data[7];
			osmo_signal_dispatch(SS_CCCH, S_CCCH_RACH_LOAD, &sd);
		}
		break;
	default:
		break;
	}

	return 0;
}

static int abis_rsl_rx_cchan(struct msgb *msg)
{
	struct e1inp_sign_link *sign_link = msg->dst;
	struct abis_rsl_dchan_hdr *rslh = msgb_l2(msg);
	int rc = 0;

	msg->lchan = lchan_lookup(sign_link->trx, rslh->chan_nr,
				  "Abis RSL rx CCHAN: ");

	switch (rslh->c.msg_type) {
	case RSL_MT_CHAN_RQD:
		/* MS has requested a channel on the RACH */
		rc = rsl_rx_chan_rqd(msg);
		break;
	case RSL_MT_CCCH_LOAD_IND:
		/* current load on the CCCH */
		rc = rsl_rx_ccch_load(msg);
		break;
	case RSL_MT_DELETE_IND:
		/* CCCH overloaded, IMM_ASSIGN was dropped */
	case RSL_MT_CBCH_LOAD_IND:
		/* current load on the CBCH */
		LOGP(DRSL, LOGL_NOTICE, "Unimplemented Abis RSL TRX message "
			"type 0x%02x\n", rslh->c.msg_type);
		break;
	default:
		LOGP(DRSL, LOGL_NOTICE, "Unknown Abis RSL TRX message type "
			"0x%02x\n", rslh->c.msg_type);
		return -EINVAL;
	}

	return rc;
}

static int rsl_rx_rll_err_ind(struct msgb *msg)
{
	struct tlv_parsed tp;
	struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
	uint8_t rlm_cause;

	rsl_tlv_parse(&tp, rllh->data, msgb_l2len(msg) - sizeof(*rllh));
	if (!TLVP_PRESENT(&tp, RSL_IE_RLM_CAUSE)) {
		LOGP(DRLL, LOGL_ERROR,
			"%s ERROR INDICATION without mandantory cause.\n",
			gsm_lchan_name(msg->lchan));
		return -1;
	}

	rlm_cause = *TLVP_VAL(&tp, RSL_IE_RLM_CAUSE);
	LOGP(DRLL, LOGL_ERROR, "%s ERROR INDICATION cause=%s in state=%s\n",
		gsm_lchan_name(msg->lchan),
		rsl_rlm_cause_name(rlm_cause),
		gsm_lchans_name(msg->lchan->state));

	rll_indication(msg->lchan, rllh->link_id, BSC_RLLR_IND_ERR_IND);

	if (rlm_cause == RLL_CAUSE_T200_EXPIRED) {
		rate_ctr_inc(&msg->lchan->ts->trx->bts->network->bsc_ctrs->ctr[BSC_CTR_CHAN_RLL_ERR]);
		return rsl_rf_chan_release_err(msg->lchan);
	}

	return 0;
}

static void rsl_handle_release(struct gsm_lchan *lchan)
{
	int sapi;
	struct gsm_bts *bts;

	/*
	 * Maybe only one link/SAPI was releasd or the error handling
	 * was activated. Just return now and let the other code handle
	 * it.
	 */
	if (lchan->state != LCHAN_S_REL_REQ)
		return;

	for (sapi = 0; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
		if (lchan->sapis[sapi] == LCHAN_SAPI_UNUSED)
			continue;
		LOGP(DRSL, LOGL_DEBUG, "%s waiting for SAPI=%d to be released.\n",
		     gsm_lchan_name(lchan), sapi);
		return;
	}


	/* Stop T3109 and wait for T3111 before re-using the channel */
	osmo_timer_del(&lchan->T3109);
	lchan->T3111.cb = t3111_expired;
	lchan->T3111.data = lchan;
	bts = lchan->ts->trx->bts;
	osmo_timer_schedule(&lchan->T3111, bts->network->T3111, 0);
}

/*	ESTABLISH INDICATION, LOCATION AREA UPDATE REQUEST
	0x02, 0x06,
	0x01, 0x20,
	0x02, 0x00,
	0x0b, 0x00, 0x0f, 0x05, 0x08, ... */

static int abis_rsl_rx_rll(struct msgb *msg)
{
	struct e1inp_sign_link *sign_link = msg->dst;
	struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
	int rc = 0;
	char *ts_name;
	uint8_t sapi = rllh->link_id & 7;

	msg->lchan = lchan_lookup(sign_link->trx, rllh->chan_nr,
				  "Abis RSL rx RLL: ");
	ts_name = gsm_lchan_name(msg->lchan);
	DEBUGP(DRLL, "%s SAPI=%u ", ts_name, sapi);
	
	switch (rllh->c.msg_type) {
	case RSL_MT_DATA_IND:
		DEBUGPC(DRLL, "DATA INDICATION\n");
		if (msgb_l2len(msg) >
		    sizeof(struct abis_rsl_common_hdr) + sizeof(*rllh) &&
		    rllh->data[0] == RSL_IE_L3_INFO) {
			msg->l3h = &rllh->data[3];
			return gsm0408_rcvmsg(msg, rllh->link_id);
		}
		break;
	case RSL_MT_EST_IND:
		DEBUGPC(DRLL, "ESTABLISH INDICATION\n");
		/* lchan is established, stop T3101 */
		msg->lchan->sapis[rllh->link_id & 0x7] = LCHAN_SAPI_MS;
		osmo_timer_del(&msg->lchan->T3101);
		if (msgb_l2len(msg) >
		    sizeof(struct abis_rsl_common_hdr) + sizeof(*rllh) &&
		    rllh->data[0] == RSL_IE_L3_INFO) {
			msg->l3h = &rllh->data[3];
			return gsm0408_rcvmsg(msg, rllh->link_id);
		}
		break;
	case RSL_MT_EST_CONF:
		DEBUGPC(DRLL, "ESTABLISH CONFIRM\n");
		msg->lchan->sapis[rllh->link_id & 0x7] = LCHAN_SAPI_NET;
		rll_indication(msg->lchan, rllh->link_id,
				  BSC_RLLR_IND_EST_CONF);
		break;
	case RSL_MT_REL_IND:
		/* BTS informs us of having received  DISC from MS */
		DEBUGPC(DRLL, "RELEASE INDICATION\n");
		msg->lchan->sapis[rllh->link_id & 0x7] = LCHAN_SAPI_UNUSED;
		rll_indication(msg->lchan, rllh->link_id,
				  BSC_RLLR_IND_REL_IND);
		rsl_handle_release(msg->lchan);
		break;
	case RSL_MT_REL_CONF:
		/* BTS informs us of having received UA from MS,
		 * in response to DISC that we've sent earlier */
		DEBUGPC(DRLL, "RELEASE CONFIRMATION\n");
		msg->lchan->sapis[rllh->link_id & 0x7] = LCHAN_SAPI_UNUSED;
		rsl_handle_release(msg->lchan);
		break;
	case RSL_MT_ERROR_IND:
		DEBUGPC(DRLL, "ERROR INDICATION\n");
		rc = rsl_rx_rll_err_ind(msg);
		break;
	case RSL_MT_UNIT_DATA_IND:
		DEBUGPC(DRLL, "UNIT DATA INDICATION\n");
		LOGP(DRLL, LOGL_NOTICE, "unimplemented Abis RLL message "
			"type 0x%02x\n", rllh->c.msg_type);
		break;
	default:
		DEBUGPC(DRLL, "UNKNOWN\n");
		LOGP(DRLL, LOGL_NOTICE, "unknown Abis RLL message "
			"type 0x%02x\n", rllh->c.msg_type);
	}
	return rc;
}

static uint8_t ipa_smod_s_for_lchan(struct gsm_lchan *lchan)
{
	switch (lchan->tch_mode) {
	case GSM48_CMODE_SPEECH_V1:
		switch (lchan->type) {
		case GSM_LCHAN_TCH_F:
			return 0x00;
		case GSM_LCHAN_TCH_H:
			return 0x03;
		default:
			break;
		}
		break;
	case GSM48_CMODE_SPEECH_EFR:
		switch (lchan->type) {
		case GSM_LCHAN_TCH_F:
			return 0x01;
		/* there's no half-rate EFR */
		default:
			break;
		}
		break;
	case GSM48_CMODE_SPEECH_AMR:
		switch (lchan->type) {
		case GSM_LCHAN_TCH_F:
			return 0x02;
		case GSM_LCHAN_TCH_H:
			return 0x05;
		default:
			break;
		}
		break;
	default:
		break;
	}
	LOGP(DRSL, LOGL_ERROR, "Cannot determine ip.access speech mode for "
		"tch_mode == 0x%02x\n", lchan->tch_mode);
	return 0;
}

static uint8_t ipa_rtp_pt_for_lchan(struct gsm_lchan *lchan)
{
	switch (lchan->tch_mode) {
	case GSM48_CMODE_SPEECH_V1:
		switch (lchan->type) {
		case GSM_LCHAN_TCH_F:
			return RTP_PT_GSM_FULL;
		case GSM_LCHAN_TCH_H:
			return RTP_PT_GSM_HALF;
		default:
			break;
		}
		break;
	case GSM48_CMODE_SPEECH_EFR:
		switch (lchan->type) {
		case GSM_LCHAN_TCH_F:
			return RTP_PT_GSM_EFR;
		/* there's no half-rate EFR */
		default:
			break;
		}
		break;
	case GSM48_CMODE_SPEECH_AMR:
		switch (lchan->type) {
		case GSM_LCHAN_TCH_F:
		case GSM_LCHAN_TCH_H:
			return RTP_PT_AMR;
		default:
			break;
		}
		break;
	default:
		break;
	}
	LOGP(DRSL, LOGL_ERROR, "Cannot determine ip.access rtp payload type for "
		"tch_mode == 0x%02x\n & lchan_type == %d",
		lchan->tch_mode, lchan->type);
	return 0;
}

/* ip.access specific RSL extensions */
static void ipac_parse_rtp(struct gsm_lchan *lchan, struct tlv_parsed *tv)
{
	struct in_addr ip;
	uint16_t port, conn_id;

	if (TLVP_PRESENT(tv, RSL_IE_IPAC_LOCAL_IP)) {
		ip.s_addr = tlvp_val32_unal(tv, RSL_IE_IPAC_LOCAL_IP);
		DEBUGPC(DRSL, "LOCAL_IP=%s ", inet_ntoa(ip));
		lchan->abis_ip.bound_ip = ntohl(ip.s_addr);
	}

	if (TLVP_PRESENT(tv, RSL_IE_IPAC_LOCAL_PORT)) {
		port = tlvp_val16_unal(tv, RSL_IE_IPAC_LOCAL_PORT);
		port = ntohs(port);
		DEBUGPC(DRSL, "LOCAL_PORT=%u ", port);
		lchan->abis_ip.bound_port = port;
	}

	if (TLVP_PRESENT(tv, RSL_IE_IPAC_CONN_ID)) {
		conn_id = tlvp_val16_unal(tv, RSL_IE_IPAC_CONN_ID);
		conn_id = ntohs(conn_id);
		DEBUGPC(DRSL, "CON_ID=%u ", conn_id);
		lchan->abis_ip.conn_id = conn_id;
	}

	if (TLVP_PRESENT(tv, RSL_IE_IPAC_RTP_PAYLOAD2)) {
		lchan->abis_ip.rtp_payload2 =
				*TLVP_VAL(tv, RSL_IE_IPAC_RTP_PAYLOAD2);
		DEBUGPC(DRSL, "RTP_PAYLOAD2=0x%02x ",
			lchan->abis_ip.rtp_payload2);
	}

	if (TLVP_PRESENT(tv, RSL_IE_IPAC_SPEECH_MODE)) {
		lchan->abis_ip.speech_mode =
				*TLVP_VAL(tv, RSL_IE_IPAC_SPEECH_MODE);
		DEBUGPC(DRSL, "speech_mode=0x%02x ",
			lchan->abis_ip.speech_mode);
	}

	if (TLVP_PRESENT(tv, RSL_IE_IPAC_REMOTE_IP)) {
		ip.s_addr = tlvp_val32_unal(tv, RSL_IE_IPAC_REMOTE_IP);
		DEBUGPC(DRSL, "REMOTE_IP=%s ", inet_ntoa(ip));
		lchan->abis_ip.connect_ip = ntohl(ip.s_addr);
	}

	if (TLVP_PRESENT(tv, RSL_IE_IPAC_REMOTE_PORT)) {
		port = tlvp_val16_unal(tv, RSL_IE_IPAC_REMOTE_PORT);
		port = ntohs(port);
		DEBUGPC(DRSL, "REMOTE_PORT=%u ", port);
		lchan->abis_ip.connect_port = port;
	}
}

/*! \brief Issue IPA RSL CRCX to configure RTP on BTS side
 *  \param[in] lchan Logical Channel for which we issue CRCX
 */
int rsl_ipacc_crcx(struct gsm_lchan *lchan)
{
	struct msgb *msg = rsl_msgb_alloc();
	struct abis_rsl_dchan_hdr *dh;

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_IPAC_CRCX);
	dh->c.msg_discr = ABIS_RSL_MDISC_IPACCESS;
	dh->chan_nr = gsm_lchan2chan_nr(lchan);

	/* 0x1- == receive-only, 0x-1 == EFR codec */
	lchan->abis_ip.speech_mode = 0x10 | ipa_smod_s_for_lchan(lchan);
	lchan->abis_ip.rtp_payload = ipa_rtp_pt_for_lchan(lchan);
	msgb_tv_put(msg, RSL_IE_IPAC_SPEECH_MODE, lchan->abis_ip.speech_mode);
	msgb_tv_put(msg, RSL_IE_IPAC_RTP_PAYLOAD, lchan->abis_ip.rtp_payload);

	DEBUGP(DRSL, "%s IPAC_BIND speech_mode=0x%02x RTP_PAYLOAD=%d\n",
		gsm_lchan_name(lchan), lchan->abis_ip.speech_mode,
		lchan->abis_ip.rtp_payload);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/*! \brief Issue IPA RSL MDCX to configure MGW-side of RTP
 *  \param[in] lchan Logical Channel for which we issue MDCX
 *  \param[in] ip Remote (MGW) IP address for RTP
 *  \param[in] port Remote (MGW) UDP port number for RTP
 *  \param[in] rtp_payload2 Contents of RTP PAYLOAD 2 IE
 */
int rsl_ipacc_mdcx(struct gsm_lchan *lchan, uint32_t ip, uint16_t port,
		   uint8_t rtp_payload2)
{
	struct msgb *msg = rsl_msgb_alloc();
	struct abis_rsl_dchan_hdr *dh;
	uint32_t *att_ip;
	struct in_addr ia;

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_IPAC_MDCX);
	dh->c.msg_discr = ABIS_RSL_MDISC_IPACCESS;
	dh->chan_nr = gsm_lchan2chan_nr(lchan);

	/* we need to store these now as MDCX_ACK does not return them :( */
	lchan->abis_ip.rtp_payload2 = rtp_payload2;
	lchan->abis_ip.connect_port = port;
	lchan->abis_ip.connect_ip = ip;

	/* 0x0- == both directions, 0x-1 == EFR codec */
	lchan->abis_ip.speech_mode = 0x00 | ipa_smod_s_for_lchan(lchan);
	lchan->abis_ip.rtp_payload = ipa_rtp_pt_for_lchan(lchan);

	ia.s_addr = htonl(ip);
	DEBUGP(DRSL, "%s IPAC_MDCX IP=%s PORT=%d RTP_PAYLOAD=%d RTP_PAYLOAD2=%d "
		"CONN_ID=%d speech_mode=0x%02x\n", gsm_lchan_name(lchan),
		inet_ntoa(ia), port, lchan->abis_ip.rtp_payload, rtp_payload2,
		lchan->abis_ip.conn_id, lchan->abis_ip.speech_mode);

	msgb_tv16_put(msg, RSL_IE_IPAC_CONN_ID, lchan->abis_ip.conn_id);
	msgb_v_put(msg, RSL_IE_IPAC_REMOTE_IP);
	att_ip = (uint32_t *) msgb_put(msg, sizeof(ip));
	*att_ip = ia.s_addr;
	msgb_tv16_put(msg, RSL_IE_IPAC_REMOTE_PORT, port);
	msgb_tv_put(msg, RSL_IE_IPAC_SPEECH_MODE, lchan->abis_ip.speech_mode);
	msgb_tv_put(msg, RSL_IE_IPAC_RTP_PAYLOAD, lchan->abis_ip.rtp_payload);
	if (rtp_payload2)
		msgb_tv_put(msg, RSL_IE_IPAC_RTP_PAYLOAD2, rtp_payload2);

	msg->dst = lchan->ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/* tell BTS to connect RTP stream to our local RTP socket */
int rsl_ipacc_mdcx_to_rtpsock(struct gsm_lchan *lchan)
{
	struct rtp_socket *rs = lchan->abis_ip.rtp_socket;
	int rc;

	rc = rsl_ipacc_mdcx(lchan, ntohl(rs->rtp.sin_local.sin_addr.s_addr),
				ntohs(rs->rtp.sin_local.sin_port),
			/* FIXME: use RTP payload of bound socket, not BTS*/
				lchan->abis_ip.rtp_payload2);

	return rc;
}

int rsl_ipacc_pdch_activate(struct gsm_bts_trx_ts *ts, int act)
{
	struct msgb *msg = rsl_msgb_alloc();
	struct abis_rsl_dchan_hdr *dh;
	uint8_t msg_type;

	if (ts->flags & TS_F_PDCH_PENDING_MASK) {
		LOGP(DRSL, LOGL_ERROR,
		     "%s PDCH %s requested, but a PDCH%s%s is still pending\n",
		     gsm_ts_name(ts),
		     act ? "ACT" : "DEACT",
		     ts->flags & TS_F_PDCH_ACT_PENDING? " ACT" : "",
		     ts->flags & TS_F_PDCH_DEACT_PENDING? " DEACT" : "");
		return -EINVAL;
	}

	if (act){
		/* Callers should heed the GPRS mode. */
		OSMO_ASSERT(ts->trx->bts->gprs.mode != BTS_GPRS_NONE);
		msg_type = RSL_MT_IPAC_PDCH_ACT;
		ts->flags |= TS_F_PDCH_ACT_PENDING;
	} else {
		msg_type = RSL_MT_IPAC_PDCH_DEACT;
		ts->flags |= TS_F_PDCH_DEACT_PENDING;
	}
	/* TODO add timeout to cancel PDCH DE/ACT */

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh));
	init_dchan_hdr(dh, msg_type);
	dh->c.msg_discr = ABIS_RSL_MDISC_DED_CHAN;
	dh->chan_nr = gsm_pchan2chan_nr(GSM_PCHAN_PDCH, ts->nr, 0);

	DEBUGP(DRSL, "%s IPAC PDCH %sACT\n", gsm_ts_name(ts),
		act ? "" : "DE");

	msg->dst = ts->trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

static int abis_rsl_rx_ipacc_crcx_ack(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *dh = msgb_l2(msg);
	struct tlv_parsed tv;
	struct gsm_lchan *lchan = msg->lchan;

	/* the BTS has acknowledged a local bind, it now tells us the IP
	* address and port number to which it has bound the given logical
	* channel */

	rsl_tlv_parse(&tv, dh->data, msgb_l2len(msg)-sizeof(*dh));
	if (!TLVP_PRESENT(&tv, RSL_IE_IPAC_LOCAL_PORT) ||
	    !TLVP_PRESENT(&tv, RSL_IE_IPAC_LOCAL_IP) ||
	    !TLVP_PRESENT(&tv, RSL_IE_IPAC_CONN_ID)) {
		LOGP(DRSL, LOGL_NOTICE, "mandatory IE missing");
		return -EINVAL;
	}

	ipac_parse_rtp(lchan, &tv);

	osmo_signal_dispatch(SS_ABISIP, S_ABISIP_CRCX_ACK, msg->lchan);

	return 0;
}

static int abis_rsl_rx_ipacc_mdcx_ack(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *dh = msgb_l2(msg);
	struct tlv_parsed tv;
	struct gsm_lchan *lchan = msg->lchan;

	/* the BTS has acknowledged a remote connect request and
	 * it now tells us the IP address and port number to which it has
	 * connected the given logical channel */

	rsl_tlv_parse(&tv, dh->data, msgb_l2len(msg)-sizeof(*dh));
	ipac_parse_rtp(lchan, &tv);
	osmo_signal_dispatch(SS_ABISIP, S_ABISIP_MDCX_ACK, msg->lchan);

	return 0;
}

static int abis_rsl_rx_ipacc_dlcx_ind(struct msgb *msg)
{
	struct abis_rsl_dchan_hdr *dh = msgb_l2(msg);
	struct tlv_parsed tv;

	rsl_tlv_parse(&tv, dh->data, msgb_l2len(msg)-sizeof(*dh));

	if (TLVP_PRESENT(&tv, RSL_IE_CAUSE))
		print_rsl_cause(LOGL_DEBUG, TLVP_VAL(&tv, RSL_IE_CAUSE),
				TLVP_LEN(&tv, RSL_IE_CAUSE));

	osmo_signal_dispatch(SS_ABISIP, S_ABISIP_DLCX_IND, msg->lchan);

	return 0;
}

static int abis_rsl_rx_ipacc(struct msgb *msg)
{
	struct e1inp_sign_link *sign_link = msg->dst;
	struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
	char *ts_name;
	int rc = 0;

	msg->lchan = lchan_lookup(sign_link->trx, rllh->chan_nr,
				  "Abis RSL rx IPACC: ");
	ts_name = gsm_lchan_name(msg->lchan);
	
	switch (rllh->c.msg_type) {
	case RSL_MT_IPAC_CRCX_ACK:
		DEBUGP(DRSL, "%s IPAC_CRCX_ACK ", ts_name);
		rc = abis_rsl_rx_ipacc_crcx_ack(msg);
		break;
	case RSL_MT_IPAC_CRCX_NACK:
		/* somehow the BTS was unable to bind the lchan to its local
		 * port?!? */
		LOGP(DRSL, LOGL_ERROR, "%s IPAC_CRCX_NACK\n", ts_name);
		break;
	case RSL_MT_IPAC_MDCX_ACK:
		/* the BTS tells us that a connect operation was successful */
		DEBUGP(DRSL, "%s IPAC_MDCX_ACK ", ts_name);
		rc = abis_rsl_rx_ipacc_mdcx_ack(msg);
		break;
	case RSL_MT_IPAC_MDCX_NACK:
		/* somehow the BTS was unable to connect the lchan to a remote
		 * port */
		LOGP(DRSL, LOGL_ERROR, "%s IPAC_MDCX_NACK\n", ts_name);
		break;
	case RSL_MT_IPAC_DLCX_IND:
		DEBUGP(DRSL, "%s IPAC_DLCX_IND ", ts_name);
		rc = abis_rsl_rx_ipacc_dlcx_ind(msg);
		break;
	default:
		LOGP(DRSL, LOGL_NOTICE, "Unknown ip.access msg_type 0x%02x\n",
			rllh->c.msg_type);
		break;
	}
	DEBUGPC(DRSL, "\n");

	return rc;
}

int dyn_ts_switchover_start(struct gsm_bts_trx_ts *ts,
			    enum gsm_phys_chan_config to_pchan)
{
	int ss;
	int rc = -EIO;

	OSMO_ASSERT(ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH);
	DEBUGP(DRSL, "%s starting switchover to %s\n",
	       gsm_ts_and_pchan_name(ts), gsm_pchan_name(to_pchan));

	if (ts->dyn.pchan_is != ts->dyn.pchan_want) {
		LOGP(DRSL, LOGL_ERROR,
		     "%s: Attempt to switch dynamic channel to %s,"
		     " but is already in switchover.\n",
		     gsm_ts_and_pchan_name(ts),
		     gsm_pchan_name(to_pchan));
		return ts->dyn.pchan_want == to_pchan? 0 : -EAGAIN;
	}

	if (ts->dyn.pchan_is == to_pchan) {
		LOGP(DRSL, LOGL_INFO,
		     "%s %s Already is in %s mode, cannot switchover.\n",
		     gsm_ts_name(ts), gsm_pchan_name(ts->pchan),
		     gsm_pchan_name(to_pchan));
		return -EINVAL;
	}

	/* Paranoia: let's make sure all is indeed released. */
	for (ss = 0; ss < ts_subslots(ts); ss++) {
		struct gsm_lchan *lc = &ts->lchan[ss];
		if (lc->state != LCHAN_S_NONE) {
			LOGP(DRSL, LOGL_ERROR,
			     "%s Attempt to switch dynamic channel to %s,"
			     " but is not fully released.\n",
			     gsm_ts_and_pchan_name(ts),
			     gsm_pchan_name(to_pchan));
			return -EAGAIN;
		}
	}

	/* Record that we're busy switching. */
	ts->dyn.pchan_want = to_pchan;

	/*
	 * To switch from PDCH, we need to initiate the release from the BSC
	 * side. dyn_ts_switchover_continue() will be called from
	 * rsl_rx_rf_chan_rel_ack(). PDCH is always on lchan[0].
	 */
	if (ts->dyn.pchan_is == GSM_PCHAN_PDCH) {
		rsl_lchan_set_state(ts->lchan, LCHAN_S_REL_REQ);
		rc = rsl_rf_chan_release(ts->lchan, 0, SACCH_NONE);
		if (rc) {
			LOGP(DRSL, LOGL_ERROR,
			     "%s RSL RF Chan Release failed\n",
			     gsm_ts_and_pchan_name(ts));
			return dyn_ts_switchover_failed(ts, rc);
		}
		return 0;
	}

	/*
	 * To switch from TCH/F and TCH/H pchans, this has been called from
	 * rsl_rx_rf_chan_rel_ack(), i.e. release is complete. Go ahead and
	 * activate as new type. This will always be PDCH.
	 */
	return dyn_ts_switchover_continue(ts);
}

static int dyn_ts_switchover_continue(struct gsm_bts_trx_ts *ts)
{
	int rc;
	uint8_t act_type;
	uint8_t ho_ref;
	int ss;
	struct gsm_lchan *lchan;

	OSMO_ASSERT(ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH);
	DEBUGP(DRSL, "%s switchover: release complete,"
	       " activating new pchan type\n",
	       gsm_ts_and_pchan_name(ts));

	if (ts->dyn.pchan_is == ts->dyn.pchan_want) {
		LOGP(DRSL, LOGL_ERROR,
		     "%s Requested to switchover dynamic channel to the"
		     " same type it is already in.\n",
		     gsm_ts_and_pchan_name(ts));
		return 0;
	}

	for (ss = 0; ss < ts_subslots(ts); ss++) {
		lchan = &ts->lchan[ss];
		if (lchan->rqd_ref) {
			LOGP(DRSL, LOGL_ERROR,
			     "%s During dyn TS switchover, expecting no"
			     " Request Reference to be pending. Discarding!\n",
			     gsm_lchan_name(lchan));
			talloc_free(lchan->rqd_ref);
			lchan->rqd_ref = NULL;
		}
	}

	/*
	 * When switching pchan modes, all lchans are unused. So always
	 * activate whatever wants to be activated on the first lchan.  (We
	 * wouldn't remember to use lchan[1] across e.g. a PDCH deact anyway)
	 */
	lchan = ts->lchan;
	
	/*
	 * For TCH/x, the lchan->type has been set in lchan_alloc(), but it may
	 * have been lost during channel release due to dynamic switchover.
	 *
	 * For PDCH, the lchan->type will actually remain NONE.
	 * TODO: set GSM_LCHAN_PDTCH?
	 */
	switch (ts->dyn.pchan_want) {
	case GSM_PCHAN_TCH_F:
		lchan->type = GSM_LCHAN_TCH_F;
		break;
	case GSM_PCHAN_TCH_H:
		lchan->type = GSM_LCHAN_TCH_H;
		break;
	case GSM_PCHAN_PDCH:
		lchan->type = GSM_LCHAN_NONE;
		break;
	default:
		LOGP(DRSL, LOGL_ERROR,
		     "%s Invalid target pchan for dynamic TS\n",
		     gsm_ts_and_pchan_name(ts));
	}

	act_type = (ts->dyn.pchan_want == GSM_PCHAN_PDCH)
		? RSL_ACT_OSMO_PDCH
		: lchan->dyn.act_type;
	ho_ref = (ts->dyn.pchan_want == GSM_PCHAN_PDCH)
		? 0
		: lchan->dyn.ho_ref;

	/* Fetch the rqd_ref back from before switchover started. */
	lchan->rqd_ref = lchan->dyn.rqd_ref;
	lchan->rqd_ta = lchan->dyn.rqd_ta;
	lchan->dyn.rqd_ref = NULL;
	lchan->dyn.rqd_ta = 0;

	/* During switchover, we have received a release ack, which means that
	 * the act_timer has been stopped. Start the timer again so we mark
	 * this channel broken if the activation ack comes too late. */
	lchan->act_timer.cb = lchan_act_tmr_cb;
	lchan->act_timer.data = lchan;
	osmo_timer_schedule(&lchan->act_timer, 4, 0);

	rc = rsl_chan_activate_lchan(lchan, act_type, ho_ref);
	if (rc) {
		LOGP(DRSL, LOGL_ERROR,
		     "%s RSL Chan Activate failed\n",
		     gsm_ts_and_pchan_name(ts));
		return dyn_ts_switchover_failed(ts, rc);
	}
	return 0;
}

static int dyn_ts_switchover_failed(struct gsm_bts_trx_ts *ts, int rc)
{
	ts->dyn.pchan_want = ts->dyn.pchan_is;
	LOGP(DRSL, LOGL_ERROR, "%s Error %d during dynamic channel switchover."
	     " Going back to previous pchan.\n", gsm_ts_and_pchan_name(ts),
	     rc);
	return rc;
}

static void dyn_ts_switchover_complete(struct gsm_lchan *lchan)
{
	enum gsm_phys_chan_config pchan_act;
	enum gsm_phys_chan_config pchan_was;
	struct gsm_bts_trx_ts *ts = lchan->ts;

	OSMO_ASSERT(ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH);

	pchan_act = pchan_for_lchant(lchan->type);
	/*
	 * Paranoia: do the types match?
	 * In case of errors: we've received an act ack already, so what to do
	 * about it? Logging the error should suffice for now.
	 */
	if (pchan_act != ts->dyn.pchan_want)
		LOGP(DRSL, LOGL_ERROR,
		     "%s Requested transition does not match lchan type %s\n",
		     gsm_ts_and_pchan_name(ts),
		     gsm_lchant_name(lchan->type));

	pchan_was = ts->dyn.pchan_is;
	ts->dyn.pchan_is = ts->dyn.pchan_want = pchan_act;

	if (pchan_was != ts->dyn.pchan_is)
		LOGP(DRSL, LOGL_INFO, "%s switchover from %s complete.\n",
		     gsm_ts_and_pchan_name(ts), gsm_pchan_name(pchan_was));
}

/* Entry-point where L2 RSL from BTS enters */
int abis_rsl_rcvmsg(struct msgb *msg)
{
	struct abis_rsl_common_hdr *rslh;
	int rc = 0;

	if (!msg) {
		DEBUGP(DRSL, "Empty RSL msg?..\n");
		return -1;
	}

	if (msgb_l2len(msg) < sizeof(*rslh)) {
		DEBUGP(DRSL, "Truncated RSL message with l2len: %u\n", msgb_l2len(msg));
		msgb_free(msg);
		return -1;
	}

	rslh = msgb_l2(msg);

	switch (rslh->msg_discr & 0xfe) {
	case ABIS_RSL_MDISC_RLL:
		rc = abis_rsl_rx_rll(msg);
		break;
	case ABIS_RSL_MDISC_DED_CHAN:
		rc = abis_rsl_rx_dchan(msg);
		break;
	case ABIS_RSL_MDISC_COM_CHAN:
		rc = abis_rsl_rx_cchan(msg);
		break;
	case ABIS_RSL_MDISC_TRX:
		rc = abis_rsl_rx_trx(msg);
		break;
	case ABIS_RSL_MDISC_LOC:
		LOGP(DRSL, LOGL_NOTICE, "unimplemented RSL msg disc 0x%02x\n",
			rslh->msg_discr);
		break;
	case ABIS_RSL_MDISC_IPACCESS:
		rc = abis_rsl_rx_ipacc(msg);
		break;
	default:
		LOGP(DRSL, LOGL_NOTICE, "unknown RSL message discriminator "
			"0x%02x\n", rslh->msg_discr);
		rc = -EINVAL;
	}
	msgb_free(msg);
	return rc;
}

int rsl_sms_cb_command(struct gsm_bts *bts, uint8_t chan_number,
		       struct rsl_ie_cb_cmd_type cb_command,
		       const uint8_t *data, int len)
{
	struct abis_rsl_dchan_hdr *dh;
	struct msgb *cb_cmd;

	cb_cmd = rsl_msgb_alloc();
	if (!cb_cmd)
		return -1;

	dh = (struct abis_rsl_dchan_hdr *) msgb_put(cb_cmd, sizeof(*dh));
	init_dchan_hdr(dh, RSL_MT_SMS_BC_CMD);
	dh->c.msg_discr = ABIS_RSL_MDISC_COM_CHAN;
	dh->chan_nr = chan_number; /* TODO: check the chan config */

	msgb_tv_put(cb_cmd, RSL_IE_CB_CMD_TYPE, *(uint8_t*)&cb_command);
	msgb_tlv_put(cb_cmd, RSL_IE_SMSCB_MSG, len, data);

	cb_cmd->dst = bts->c0->rsl_link;

	return abis_rsl_sendmsg(cb_cmd);
}

int rsl_nokia_si_begin(struct gsm_bts_trx *trx)
{
	struct abis_rsl_common_hdr *ch;
	struct msgb *msg = rsl_msgb_alloc();

	ch = (struct abis_rsl_common_hdr *) msgb_put(msg, sizeof(*ch));
	ch->msg_discr = ABIS_RSL_MDISC_TRX;
	ch->msg_type = 0x40; /* Nokia SI Begin */

	msg->dst = trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

int rsl_nokia_si_end(struct gsm_bts_trx *trx)
{
	struct abis_rsl_common_hdr *ch;
	struct msgb *msg = rsl_msgb_alloc();

	ch = (struct abis_rsl_common_hdr *) msgb_put(msg, sizeof(*ch));
	ch->msg_discr = ABIS_RSL_MDISC_TRX;
	ch->msg_type = 0x41;  /* Nokia SI End */

	msgb_tv_put(msg, 0xFD, 0x00); /* Nokia Pagemode Info, No paging reorganisation required */

	msg->dst = trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

int rsl_bs_power_control(struct gsm_bts_trx *trx, uint8_t channel, uint8_t reduction)
{
	struct abis_rsl_common_hdr *ch;
	struct msgb *msg = rsl_msgb_alloc();

	ch = (struct abis_rsl_common_hdr *) msgb_put(msg, sizeof(*ch));
	ch->msg_discr = ABIS_RSL_MDISC_DED_CHAN;
	ch->msg_type = RSL_MT_BS_POWER_CONTROL;

	msgb_tv_put(msg, RSL_IE_CHAN_NR, channel);
	msgb_tv_put(msg, RSL_IE_BS_POWER, reduction); /* reduction in 2dB steps */

	msg->dst = trx->rsl_link;

	return abis_rsl_sendmsg(msg);
}

/**
 * Release all allocated SAPIs starting from @param start and
 * release them with the given release mode. Once the release
 * confirmation arrives it will be attempted to release the
 * the RF channel.
 */
int rsl_release_sapis_from(struct gsm_lchan *lchan, int start,
			enum rsl_rel_mode release_mode)
{
	int no_sapi = 1;
	int sapi;

	for (sapi = start; sapi < ARRAY_SIZE(lchan->sapis); ++sapi) {
		uint8_t link_id;
		if (lchan->sapis[sapi] == LCHAN_SAPI_UNUSED)
			continue;

		link_id = sapi;
		if (lchan->type == GSM_LCHAN_TCH_F || lchan->type == GSM_LCHAN_TCH_H)
			link_id |= 0x40;
		rsl_release_request(lchan, link_id, release_mode);
		no_sapi = 0;
	}

	return no_sapi;
}

int rsl_start_t3109(struct gsm_lchan *lchan)
{
	struct gsm_bts *bts = lchan->ts->trx->bts;

	/* Disabled, mostly legacy code */
	if (bts->network->T3109 == 0)
		return -1;

	lchan->T3109.cb = t3109_expired;
	lchan->T3109.data = lchan;
	osmo_timer_schedule(&lchan->T3109, bts->network->T3109, 0);
	return 0;
}

/**
 * \brief directly RF Channel Release the lchan
 *
 * When no SAPI was allocated, directly release the logical channel. This
 * should only be called from chan_alloc.c on channel release handling. In
 * case no SAPI was established the RF Channel can be directly released,
 */
int rsl_direct_rf_release(struct gsm_lchan *lchan)
{
	int i;
	for (i = 0; i < ARRAY_SIZE(lchan->sapis); ++i) {
		if (lchan->sapis[i] != LCHAN_SAPI_UNUSED) {
			LOGP(DRSL, LOGL_ERROR, "%s SAPI(%d) still allocated.\n",
				gsm_lchan_name(lchan), i);
			return -1;
		}
	}

	/* Now release it */
	return rsl_rf_chan_release(lchan, 0, SACCH_NONE);
}