dissolve libbsc: move all to src/osmo-bsc, link .o files

Move all of libbsc/ into osmo-bsc/, and separate/move some implementations to
allow linking from utils/* and ipaccess/* without pulling in unccessary
dependencies.

Some utilities use gsm_network and gsm_bts structs, which already include data
structures for fairly advanced uses. Move initialization that only osmo-bsc
needs into new bsc_network_init() and bsc_bts_alloc_register() functions, so
that the leaner tools can use the old gsm_* versions without the need to link
everything (e.g. handover and lchan alloc code).

In some instances, there need to be stubs if to cut off linking "just before
the RSL level" and prevent dependencies from creeping in.
- abis_rsl_rcvmsg(): the only program currently interpreting RSL messages is
  osmo-bsc, the utils are merely concerned with OML, if at all.
- paging_flush_bts(): ip.access nanobts models call this when the RSL link is
  dropped. Only osmo-bsc actually needs to do anything there.
- on_gsm_ts_init(): the mechanism to trigger timeslot initialization is related
  to OML, while this action to take on init would pull in RSL dependencies.
utils/ and ipaccess/ each have a stubs.c file to implement these stubs. Tests
implement stubs inline where required.

From src/utils/, src/ipaccess/ and tests/*/, link in .o files from osmo-bsc/.
In order for this to work, the osmo-bsc subdir must be built before the other
source trees. (An alternative would be to include the .c files as sources, but
that would re-compile them in every source tree. Not a large burden really, but
unless linking .o files gives problems, let's have the quicker build.)

Minor obvious cleanups creep in with this patch, I will not bother to name them
individually now unless code review asks me to.

Rationale:

1) libbsc has been separate to use it for osmo-nitb and osmo-bsc in the old
openbsc.git. This is no longer required, and spreading over libbsc and osmo-bsc
is distracting.

2) Recently, ridiculous linking requirements have made adding new functions
cumbersome, because libbsc has started depending on osmo-bsc/*.c
implementations: on gscon FSM and bssap functions. For example, neither
bs11_config nor ipaccess-config nor bts_test need handover_cfg or BSSMAP
message composition. It makes no sense to link the entire osmo-bsc to it, nor
do we want to keep adding stubs to each linking realm.

Change-Id: I36a586726f5818121abe54d25654819fc451d3bf

1 files changed, 591 insertions, 0 deletions

diff --git a/src/osmo-bsc/bts_ipaccess_nanobts.c b/src/osmo-bsc/bts_ipaccess_nanobts.c
new file mode 100644
index 000000000..843f264ae
--- /dev/null
+++ b/src/osmo-bsc/bts_ipaccess_nanobts.c
@@ -0,0 +1,591 @@
+/* ip.access nanoBTS specific code */
+
+/* (C) 2009-2018 by Harald Welte <laforge@gnumonks.org>
+ *
+ * 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 <arpa/inet.h>
+#include <time.h>
+
+#include <osmocom/gsm/tlv.h>
+
+#include <osmocom/bsc/gsm_data.h>
+#include <osmocom/bsc/signal.h>
+#include <osmocom/bsc/abis_nm.h>
+#include <osmocom/abis/e1_input.h>
+#include <osmocom/gsm/tlv.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/bsc/gsm_data.h>
+#include <osmocom/bsc/abis_nm.h>
+#include <osmocom/bsc/abis_rsl.h>
+#include <osmocom/bsc/debug.h>
+#include <osmocom/abis/subchan_demux.h>
+#include <osmocom/gsm/ipa.h>
+#include <osmocom/abis/ipaccess.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/bsc/ipaccess.h>
+#include <osmocom/bsc/bts_ipaccess_nanobts_omlattr.h>
+#include <osmocom/bsc/paging.h>
+
+static int bts_model_nanobts_start(struct gsm_network *net);
+static void bts_model_nanobts_e1line_bind_ops(struct e1inp_line *line);
+
+static char *get_oml_status(const struct gsm_bts *bts)
+{
+	if (bts->oml_link)
+		return all_trx_rsl_connected_unlocked(bts) ? "connected" : "degraded";
+
+	return "disconnected";
+}
+
+static bool oml_is_ts_ready(const struct gsm_bts_trx_ts *ts)
+{
+	return ts && ts->mo.nm_state.operational == NM_OPSTATE_ENABLED;
+}
+
+struct gsm_bts_model bts_model_nanobts = {
+	.type = GSM_BTS_TYPE_NANOBTS,
+	.name = "nanobts",
+	.start = bts_model_nanobts_start,
+	.oml_rcvmsg = &abis_nm_rcvmsg,
+	.oml_status = &get_oml_status,
+	.oml_is_ts_ready = oml_is_ts_ready,
+	.e1line_bind_ops = bts_model_nanobts_e1line_bind_ops, 
+	.nm_att_tlvdef = {
+		.def = {
+			/* ip.access specifics */
+			[NM_ATT_IPACC_DST_IP] =		{ TLV_TYPE_FIXED, 4 },
+			[NM_ATT_IPACC_DST_IP_PORT] =	{ TLV_TYPE_FIXED, 2 },
+			[NM_ATT_IPACC_STREAM_ID] =	{ TLV_TYPE_TV, },
+			[NM_ATT_IPACC_SEC_OML_CFG] =	{ TLV_TYPE_FIXED, 6 },
+			[NM_ATT_IPACC_IP_IF_CFG] =	{ TLV_TYPE_FIXED, 8 },
+			[NM_ATT_IPACC_IP_GW_CFG] =	{ TLV_TYPE_FIXED, 12 },
+			[NM_ATT_IPACC_IN_SERV_TIME] =	{ TLV_TYPE_FIXED, 4 },
+			[NM_ATT_IPACC_LOCATION] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_PAGING_CFG] =	{ TLV_TYPE_FIXED, 2 },
+			[NM_ATT_IPACC_UNIT_ID] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_UNIT_NAME] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_SNMP_CFG] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_PRIM_OML_CFG_LIST] = { TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_NV_FLAGS] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_FREQ_CTRL] =	{ TLV_TYPE_FIXED, 2 },
+			[NM_ATT_IPACC_PRIM_OML_FB_TOUT] = { TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_CUR_SW_CFG] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_TIMING_BUS] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_CGI] =		{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_RAC] =		{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_OBJ_VERSION] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_GPRS_PAGING_CFG]= { TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_NSEI] =		{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_BVCI] =		{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_NSVCI] =		{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_NS_CFG] =		{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_BSSGP_CFG] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_NS_LINK_CFG] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_RLC_CFG] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_ALM_THRESH_LIST]=	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_MONIT_VAL_LIST] = { TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_TIB_CONTROL] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_SUPP_FEATURES] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_CODING_SCHEMES] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_RLC_CFG_2] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_HEARTB_TOUT] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_UPTIME] =		{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_RLC_CFG_3] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_SSL_CFG] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_SEC_POSSIBLE] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_IML_SSL_STATE] =	{ TLV_TYPE_TL16V },
+			[NM_ATT_IPACC_REVOC_DATE] =	{ TLV_TYPE_TL16V },
+		},
+	},
+};
+
+
+/* Callback function to be called whenever we get a GSM 12.21 state change event */
+static int nm_statechg_event(int evt, struct nm_statechg_signal_data *nsd)
+{
+	uint8_t obj_class = nsd->obj_class;
+	void *obj = nsd->obj;
+	struct gsm_nm_state *new_state = nsd->new_state;
+
+	struct gsm_bts *bts;
+	struct gsm_bts_trx *trx;
+	struct gsm_bts_trx_ts *ts;
+	struct gsm_bts_gprs_nsvc *nsvc;
+
+	struct msgb *msgb;
+
+	if (!is_ipaccess_bts(nsd->bts))
+		return 0;
+
+	/* This event-driven BTS setup is currently only required on nanoBTS */
+
+	/* S_NM_STATECHG_ADM is called after we call chg_adm_state() and would create
+	 * endless loop */
+	if (evt != S_NM_STATECHG_OPER)
+		return 0;
+
+	switch (obj_class) {
+	case NM_OC_SITE_MANAGER:
+		bts = container_of(obj, struct gsm_bts, site_mgr);
+		if ((new_state->operational == NM_OPSTATE_ENABLED &&
+		     new_state->availability == NM_AVSTATE_OK) ||
+		    (new_state->operational == NM_OPSTATE_DISABLED &&
+		     new_state->availability == NM_AVSTATE_OFF_LINE))
+			abis_nm_opstart(bts, obj_class, 0xff, 0xff, 0xff);
+		break;
+	case NM_OC_BTS:
+		bts = obj;
+		if (new_state->availability == NM_AVSTATE_DEPENDENCY) {
+			msgb = nanobts_attr_bts_get(bts);
+			abis_nm_set_bts_attr(bts, msgb->data, msgb->len);
+			msgb_free(msgb);
+			abis_nm_chg_adm_state(bts, obj_class,
+					      bts->bts_nr, 0xff, 0xff,
+					      NM_STATE_UNLOCKED);
+			abis_nm_opstart(bts, obj_class,
+					bts->bts_nr, 0xff, 0xff);
+		}
+		break;
+	case NM_OC_CHANNEL:
+		ts = obj;
+		trx = ts->trx;
+		if (new_state->operational == NM_OPSTATE_DISABLED &&
+		    new_state->availability == NM_AVSTATE_DEPENDENCY) {
+			enum abis_nm_chan_comb ccomb =
+						abis_nm_chcomb4pchan(ts->pchan);
+			if (abis_nm_set_channel_attr(ts, ccomb) == -EINVAL) {
+				ipaccess_drop_oml(trx->bts);
+				return -1;
+			}
+			abis_nm_chg_adm_state(trx->bts, obj_class,
+					      trx->bts->bts_nr, trx->nr, ts->nr,
+					      NM_STATE_UNLOCKED);
+			abis_nm_opstart(trx->bts, obj_class,
+					trx->bts->bts_nr, trx->nr, ts->nr);
+		}
+		break;
+	case NM_OC_RADIO_CARRIER:
+		trx = obj;
+		if (new_state->operational == NM_OPSTATE_DISABLED &&
+		    new_state->availability == NM_AVSTATE_OK)
+			abis_nm_opstart(trx->bts, obj_class, trx->bts->bts_nr,
+					trx->nr, 0xff);
+		break;
+	case NM_OC_GPRS_NSE:
+		bts = container_of(obj, struct gsm_bts, gprs.nse);
+		if (bts->gprs.mode == BTS_GPRS_NONE)
+			break;
+		if (new_state->availability == NM_AVSTATE_DEPENDENCY) {
+			msgb = nanobts_attr_nse_get(bts);
+			abis_nm_ipaccess_set_attr(bts, obj_class, bts->bts_nr,
+						  0xff, 0xff, msgb->data,
+						  msgb->len);
+			msgb_free(msgb);
+			abis_nm_opstart(bts, obj_class, bts->bts_nr,
+					0xff, 0xff);
+		}
+		break;
+	case NM_OC_GPRS_CELL:
+		bts = container_of(obj, struct gsm_bts, gprs.cell);
+		if (bts->gprs.mode == BTS_GPRS_NONE)
+			break;
+		if (new_state->availability == NM_AVSTATE_DEPENDENCY) {
+			msgb = nanobts_attr_cell_get(bts);
+			abis_nm_ipaccess_set_attr(bts, obj_class, bts->bts_nr,
+						  0, 0xff, msgb->data,
+						  msgb->len);
+			msgb_free(msgb);
+			abis_nm_opstart(bts, obj_class, bts->bts_nr,
+					0, 0xff);
+			abis_nm_chg_adm_state(bts, obj_class, bts->bts_nr,
+					      0, 0xff, NM_STATE_UNLOCKED);
+			abis_nm_chg_adm_state(bts, NM_OC_GPRS_NSE, bts->bts_nr,
+					      0xff, 0xff, NM_STATE_UNLOCKED);
+		}
+		break;
+	case NM_OC_GPRS_NSVC:
+		nsvc = obj;
+		bts = nsvc->bts;
+		if (bts->gprs.mode == BTS_GPRS_NONE)
+			break;
+		/* We skip NSVC1 since we only use NSVC0 */
+		if (nsvc->id == 1)
+			break;
+		if ((new_state->availability == NM_AVSTATE_OFF_LINE) ||
+		    (new_state->availability == NM_AVSTATE_DEPENDENCY)) {
+			msgb = nanobts_attr_nscv_get(bts);
+			abis_nm_ipaccess_set_attr(bts, obj_class, bts->bts_nr,
+						  nsvc->id, 0xff,
+						  msgb->data, msgb->len);
+			msgb_free(msgb);
+			abis_nm_opstart(bts, obj_class, bts->bts_nr,
+					nsvc->id, 0xff);
+			abis_nm_chg_adm_state(bts, obj_class, bts->bts_nr,
+					      nsvc->id, 0xff,
+					      NM_STATE_UNLOCKED);
+		}
+	default:
+		break;
+	}
+	return 0;
+}
+
+/* Callback function to be called every time we receive a 12.21 SW activated report */
+static int sw_activ_rep(struct msgb *mb)
+{
+	struct abis_om_fom_hdr *foh = msgb_l3(mb);
+	struct e1inp_sign_link *sign_link = mb->dst;
+	struct gsm_bts *bts = sign_link->trx->bts;
+	struct gsm_bts_trx *trx = gsm_bts_trx_num(bts, foh->obj_inst.trx_nr);
+
+	if (!trx)
+		return -EINVAL;
+
+	if (!is_ipaccess_bts(trx->bts))
+		return 0;
+
+	switch (foh->obj_class) {
+	case NM_OC_BASEB_TRANSC:
+		abis_nm_chg_adm_state(trx->bts, foh->obj_class,
+				      trx->bts->bts_nr, trx->nr, 0xff,
+				      NM_STATE_UNLOCKED);
+		abis_nm_opstart(trx->bts, foh->obj_class,
+				trx->bts->bts_nr, trx->nr, 0xff);
+		/* TRX software is active, tell it to initiate RSL Link */
+		abis_nm_ipaccess_rsl_connect(trx, trx->bts->ip_access.rsl_ip,
+					     3003, trx->rsl_tei);
+		break;
+	case NM_OC_RADIO_CARRIER: {
+		/*
+		 * Locking the radio carrier will make it go
+		 * offline again and we would come here. The
+		 * framework should determine that there was
+		 * no change and avoid recursion.
+		 *
+		 * This code is here to make sure that on start
+		 * a TRX remains locked.
+		 */
+		int rc_state = trx->mo.nm_state.administrative;
+		/* Patch ARFCN into radio attribute */
+		struct msgb *msgb = nanobts_attr_radio_get(trx->bts, trx);
+		abis_nm_set_radio_attr(trx, msgb->data, msgb->len);
+		msgb_free(msgb);
+		abis_nm_chg_adm_state(trx->bts, foh->obj_class,
+				      trx->bts->bts_nr, trx->nr, 0xff,
+				      rc_state);
+		abis_nm_opstart(trx->bts, foh->obj_class, trx->bts->bts_nr,
+				trx->nr, 0xff);
+		break;
+		}
+	}
+	return 0;
+}
+
+static struct gsm_bts_trx_ts *gsm_bts_trx_ts(struct gsm_network *net,
+					     int bts_nr, int trx_nr, int ts_nr)
+{
+	struct gsm_bts *bts;
+	struct gsm_bts_trx *trx;
+	bts = gsm_bts_num(net, bts_nr);
+	if (!bts)
+		return NULL;
+	trx = gsm_bts_trx_by_nr(bts, trx_nr);
+	if (!trx)
+		return NULL;
+	if (ts_nr < 0 || ts_nr > ARRAY_SIZE(trx->ts))
+		return NULL;
+	return &trx->ts[ts_nr];
+}
+
+static void nm_rx_opstart_ack_chan(struct abis_om_fom_hdr *foh)
+{
+	struct gsm_bts_trx_ts *ts;
+	ts = gsm_bts_trx_ts(bsc_gsmnet, foh->obj_inst.bts_nr, foh->obj_inst.trx_nr, foh->obj_inst.ts_nr);
+	if (!ts) {
+		LOGP(DNM, LOGL_ERROR, "%s Channel OPSTART ACK for non-existent TS\n",
+		     abis_nm_dump_foh(foh));
+		return;
+	}
+
+	gsm_ts_check_init(ts);
+}
+
+static void nm_rx_opstart_ack(struct abis_om_fom_hdr *foh)
+{
+	switch (foh->obj_class) {
+	case NM_OC_CHANNEL:
+		nm_rx_opstart_ack_chan(foh);
+		break;
+	default:
+		break;
+	}
+}
+
+/* Callback function to be called every time we receive a signal from NM */
+static int bts_ipa_nm_sig_cb(unsigned int subsys, unsigned int signal,
+		     void *handler_data, void *signal_data)
+{
+	if (subsys != SS_NM)
+		return 0;
+
+	switch (signal) {
+	case S_NM_SW_ACTIV_REP:
+		return sw_activ_rep(signal_data);
+	case S_NM_STATECHG_OPER:
+	case S_NM_STATECHG_ADM:
+		return nm_statechg_event(signal, signal_data);
+	case S_NM_OPSTART_ACK:
+		nm_rx_opstart_ack(signal_data);
+		return 0;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static int bts_model_nanobts_start(struct gsm_network *net)
+{
+	osmo_signal_unregister_handler(SS_NM, bts_ipa_nm_sig_cb, NULL);
+	osmo_signal_register_handler(SS_NM, bts_ipa_nm_sig_cb, NULL);
+	return 0;
+}
+
+int bts_model_nanobts_init(void)
+{
+	bts_model_nanobts.features.data = &bts_model_nanobts._features_data[0];
+	bts_model_nanobts.features.data_len =
+				sizeof(bts_model_nanobts._features_data);
+
+	osmo_bts_set_feature(&bts_model_nanobts.features, BTS_FEAT_GPRS);
+	osmo_bts_set_feature(&bts_model_nanobts.features, BTS_FEAT_EGPRS);
+	osmo_bts_set_feature(&bts_model_nanobts.features, BTS_FEAT_MULTI_TSC);
+
+	return gsm_bts_model_register(&bts_model_nanobts);
+}
+
+#define OML_UP         0x0001
+#define RSL_UP         0x0002
+
+static struct gsm_bts *
+find_bts_by_unitid(struct gsm_network *net, uint16_t site_id, uint16_t bts_id)
+{
+	struct gsm_bts *bts;
+
+	llist_for_each_entry(bts, &net->bts_list, list) {
+		if (!is_ipaccess_bts(bts))
+			continue;
+
+		if (bts->ip_access.site_id == site_id &&
+		    bts->ip_access.bts_id == bts_id)
+			return bts;
+	}
+	return NULL;
+}
+
+/* These are exported because they are used by the VTY interface. */
+void ipaccess_drop_rsl(struct gsm_bts_trx *trx)
+{
+	if (!trx->rsl_link)
+		return;
+
+	LOGP(DLINP, LOGL_NOTICE, "(bts=%d,trx=%d) Dropping RSL link.\n", trx->bts->nr, trx->nr);
+	e1inp_sign_link_destroy(trx->rsl_link);
+	trx->rsl_link = NULL;
+
+	if (trx->bts->c0 == trx)
+		paging_flush_bts(trx->bts, NULL);
+}
+
+void ipaccess_drop_oml(struct gsm_bts *bts)
+{
+	struct gsm_bts *rdep_bts;
+	struct gsm_bts_trx *trx;
+
+	if (!bts->oml_link)
+		return;
+
+	LOGP(DLINP, LOGL_NOTICE, "(bts=%d) Dropping OML link.\n", bts->nr);
+	e1inp_sign_link_destroy(bts->oml_link);
+	bts->oml_link = NULL;
+	bts->uptime = 0;
+
+	/* we have issues reconnecting RSL, drop everything. */
+	llist_for_each_entry(trx, &bts->trx_list, list)
+		ipaccess_drop_rsl(trx);
+
+	gsm_bts_mark_all_ts_uninitialized(bts);
+
+	bts->ip_access.flags = 0;
+
+	/*
+	 * Go through the list and see if we are the depndency of a BTS
+	 * and then drop the BTS. This can lead to some recursion but it
+	 * should be fine in userspace.
+	 * The oml_link is serving as recursion anchor for us and
+	 * it is set to NULL some lines above.
+	 */
+	llist_for_each_entry(rdep_bts, &bts->network->bts_list, list) {
+		if (!bts_depend_is_depedency(rdep_bts, bts))
+			continue;
+		LOGP(DLINP, LOGL_NOTICE, "Dropping BTS(%u) due BTS(%u).\n",
+			rdep_bts->nr, bts->nr);
+		ipaccess_drop_oml(rdep_bts);
+	}
+}
+
+/* This function is called once the OML/RSL link becomes up. */
+static struct e1inp_sign_link *
+ipaccess_sign_link_up(void *unit_data, struct e1inp_line *line,
+		      enum e1inp_sign_type type)
+{
+	struct gsm_bts *bts;
+	struct ipaccess_unit *dev = unit_data;
+	struct e1inp_sign_link *sign_link = NULL;
+	struct timespec tp;
+	int rc;
+
+	bts = find_bts_by_unitid(bsc_gsmnet, dev->site_id, dev->bts_id);
+	if (!bts) {
+		LOGP(DLINP, LOGL_ERROR, "Unable to find BTS configuration for "
+			" %u/%u/%u, disconnecting\n", dev->site_id,
+			dev->bts_id, dev->trx_id);
+		rate_ctr_inc(&bsc_gsmnet->bsc_ctrs->ctr[BSC_CTR_UNKNOWN_UNIT_ID]);
+		return NULL;
+	}
+	DEBUGP(DLINP, "Identified BTS %u/%u/%u\n",
+			dev->site_id, dev->bts_id, dev->trx_id);
+
+	switch(type) {
+	case E1INP_SIGN_OML:
+		/* remove old OML signal link for this BTS. */
+		ipaccess_drop_oml(bts);
+
+		if (!bts_depend_check(bts)) {
+			LOGP(DLINP, LOGL_NOTICE,
+				"Dependency not full-filled for %u/%u/%u\n",
+				dev->site_id, dev->bts_id, dev->trx_id);
+			return NULL;
+		}
+
+		/* create new OML link. */
+		sign_link = bts->oml_link =
+			e1inp_sign_link_create(&line->ts[E1INP_SIGN_OML - 1],
+						E1INP_SIGN_OML, bts->c0,
+						bts->oml_tei, 0);
+		rc = clock_gettime(CLOCK_MONOTONIC, &tp);
+		bts->uptime = (rc < 0) ? 0 : tp.tv_sec; /* we don't need sub-second precision for uptime */
+		if (!(sign_link->trx->bts->ip_access.flags & OML_UP)) {
+			e1inp_event(sign_link->ts, S_L_INP_TEI_UP,
+					sign_link->tei, sign_link->sapi);
+			sign_link->trx->bts->ip_access.flags |= OML_UP;
+		}
+		break;
+	case E1INP_SIGN_RSL: {
+		struct e1inp_ts *ts;
+		struct gsm_bts_trx *trx = gsm_bts_trx_num(bts, dev->trx_id);
+
+		/* no OML link set yet? give up. */
+		if (!bts->oml_link || !trx)
+			return NULL;
+
+		/* remove old RSL link for this TRX. */
+		ipaccess_drop_rsl(trx);
+
+		/* set new RSL link for this TRX. */
+		line = bts->oml_link->ts->line;
+		ts = &line->ts[E1INP_SIGN_RSL + dev->trx_id - 1];
+		e1inp_ts_config_sign(ts, line);
+		sign_link = trx->rsl_link =
+				e1inp_sign_link_create(ts, E1INP_SIGN_RSL,
+						       trx, trx->rsl_tei, 0);
+		trx->rsl_link->ts->sign.delay = 0;
+		if (!(sign_link->trx->bts->ip_access.flags &
+					(RSL_UP << sign_link->trx->nr))) {
+			e1inp_event(sign_link->ts, S_L_INP_TEI_UP,
+					sign_link->tei, sign_link->sapi);
+			sign_link->trx->bts->ip_access.flags |=
+					(RSL_UP << sign_link->trx->nr);
+		}
+		break;
+	}
+	default:
+		break;
+	}
+	return sign_link;
+}
+
+static void ipaccess_sign_link_down(struct e1inp_line *line)
+{
+	/* No matter what link went down, we close both signal links. */
+	struct e1inp_ts *ts = &line->ts[E1INP_SIGN_OML-1];
+	struct gsm_bts *bts = NULL;
+	struct e1inp_sign_link *link;
+
+	llist_for_each_entry(link, &ts->sign.sign_links, list) {
+		/* Get bts pointer from the first element of the list. */
+		if (bts == NULL)
+			bts = link->trx->bts;
+		/* Cancel RSL connection timeout in case are still waiting for an RSL connection. */
+		if (link->trx->mo.nm_state.administrative == NM_STATE_UNLOCKED)
+			osmo_timer_del(&link->trx->rsl_connect_timeout);
+	}
+	if (bts != NULL)
+		ipaccess_drop_oml(bts);
+}
+
+/* This function is called if we receive one OML/RSL message. */
+static int ipaccess_sign_link(struct msgb *msg)
+{
+	int ret = 0;
+	struct e1inp_sign_link *link = msg->dst;
+
+	switch (link->type) {
+	case E1INP_SIGN_RSL:
+	        ret = abis_rsl_rcvmsg(msg);
+	        break;
+	case E1INP_SIGN_OML:
+	        ret = abis_nm_rcvmsg(msg);
+	        break;
+	default:
+		LOGP(DLINP, LOGL_ERROR, "Unknown signal link type %d\n",
+			link->type);
+		msgb_free(msg);
+		break;
+	}
+	return ret;
+}
+
+/* not static, ipaccess-config needs it. */
+struct e1inp_line_ops ipaccess_e1inp_line_ops = {
+	.cfg = {
+		.ipa = {
+			.addr = "0.0.0.0",
+			.role = E1INP_LINE_R_BSC,
+		},
+	},
+	.sign_link_up	= ipaccess_sign_link_up,
+	.sign_link_down	= ipaccess_sign_link_down,
+	.sign_link	= ipaccess_sign_link,
+};
+
+static void bts_model_nanobts_e1line_bind_ops(struct e1inp_line *line)
+{
+        e1inp_line_bind_ops(line, &ipaccess_e1inp_line_ops);
+}