pcu_if: original pcu sock interface from osmo-bts

The pcu interface required to support bsc co-located
pcu uses pcu_sock.c and its related header files as
a starting point.

See also:
osmo-bts.git: ced9a5d0e2c7e3371760f1c07df7b41cfe7ab71d

Change-Id: I46b0a65f1633c40053d43b57b786b042f20f12bd

3 files changed, 1101 insertions, 0 deletions

diff --git a/openbsc/include/openbsc/pcu_if.h b/openbsc/include/openbsc/pcu_if.h
new file mode 100644
index 000000000..a020c050b
--- /dev/null
+++ b/openbsc/include/openbsc/pcu_if.h
@@ -0,0 +1,25 @@
+#ifndef _PCU_IF_H
+#define _PCU_IF_H
+
+#define PCU_SOCK_DEFAULT	"/tmp/pcu_bts"
+
+extern int pcu_direct;
+
+int pcu_tx_info_ind(void);
+int pcu_tx_rts_req(struct gsm_bts_trx_ts *ts, uint8_t is_ptcch, uint32_t fn,
+	uint16_t arfcn, uint8_t block_nr);
+int pcu_tx_data_ind(struct gsm_bts_trx_ts *ts, uint8_t is_ptcch, uint32_t fn,
+	uint16_t arfcn, uint8_t block_nr, uint8_t *data, uint8_t len,
+		    int8_t rssi, uint16_t ber10k, int16_t bto, int16_t lqual);
+int pcu_tx_rach_ind(struct gsm_bts *bts, int16_t qta, uint16_t ra, uint32_t fn,
+	uint8_t is_11bit, enum ph_burst_type burst_type);
+int pcu_tx_time_ind(uint32_t fn);
+int pcu_tx_pag_req(const uint8_t *identity_lv, uint8_t chan_needed);
+int pcu_tx_pch_data_cnf(uint32_t fn, uint8_t *data, uint8_t len);
+
+int pcu_sock_init(const char *path);
+void pcu_sock_exit(void);
+
+bool pcu_connected(void);
+
+#endif /* _PCU_IF_H */
diff --git a/openbsc/include/openbsc/pcuif_proto.h b/openbsc/include/openbsc/pcuif_proto.h
new file mode 100644
index 000000000..5527238cb
--- /dev/null
+++ b/openbsc/include/openbsc/pcuif_proto.h
@@ -0,0 +1,158 @@
+#ifndef _PCUIF_PROTO_H
+#define _PCUIF_PROTO_H
+
+#define PCU_IF_VERSION		0x07
+
+/* msg_type */
+#define PCU_IF_MSG_DATA_REQ	0x00	/* send data to given channel */
+#define PCU_IF_MSG_DATA_CNF	0x01	/* confirm (e.g. transmission on PCH) */
+#define PCU_IF_MSG_DATA_IND	0x02	/* receive data from given channel */	
+#define PCU_IF_MSG_RTS_REQ	0x10	/* ready to send request */
+#define PCU_IF_MSG_RACH_IND	0x22	/* receive RACH */
+#define PCU_IF_MSG_INFO_IND	0x32	/* retrieve BTS info */
+#define PCU_IF_MSG_ACT_REQ	0x40	/* activate/deactivate PDCH */
+#define PCU_IF_MSG_TIME_IND	0x52	/* GSM time indication */
+#define PCU_IF_MSG_PAG_REQ	0x60	/* paging request */
+
+/* sapi */
+#define PCU_IF_SAPI_RACH	0x01	/* channel request on CCCH */
+#define PCU_IF_SAPI_AGCH	0x02	/* assignment on AGCH */
+#define PCU_IF_SAPI_PCH		0x03	/* paging/assignment on PCH */
+#define PCU_IF_SAPI_BCCH	0x04	/* SI on BCCH */
+#define PCU_IF_SAPI_PDTCH	0x05	/* packet data/control/ccch block */
+#define PCU_IF_SAPI_PRACH	0x06	/* packet random access channel */
+#define PCU_IF_SAPI_PTCCH	0x07	/* packet TA control channel */
+
+/* flags */
+#define PCU_IF_FLAG_ACTIVE	(1 << 0)/* BTS is active */
+#define PCU_IF_FLAG_SYSMO	(1 << 1)/* access PDCH of sysmoBTS directly */
+#define PCU_IF_FLAG_CS1		(1 << 16)
+#define PCU_IF_FLAG_CS2		(1 << 17)
+#define PCU_IF_FLAG_CS3		(1 << 18)
+#define PCU_IF_FLAG_CS4		(1 << 19)
+#define PCU_IF_FLAG_MCS1	(1 << 20)
+#define PCU_IF_FLAG_MCS2	(1 << 21)
+#define PCU_IF_FLAG_MCS3	(1 << 22)
+#define PCU_IF_FLAG_MCS4	(1 << 23)
+#define PCU_IF_FLAG_MCS5	(1 << 24)
+#define PCU_IF_FLAG_MCS6	(1 << 25)
+#define PCU_IF_FLAG_MCS7	(1 << 26)
+#define PCU_IF_FLAG_MCS8	(1 << 27)
+#define PCU_IF_FLAG_MCS9	(1 << 28)
+
+struct gsm_pcu_if_data {
+	uint8_t		sapi;
+	uint8_t		len;
+	uint8_t		data[162];
+	uint32_t	fn;
+	uint16_t	arfcn;
+	uint8_t		trx_nr;
+	uint8_t		ts_nr;
+	uint8_t		block_nr;
+	int8_t		rssi;
+	uint16_t	ber10k;		/*!< \brief BER in units of 0.01% */
+	int16_t		ta_offs_qbits;	/* !< \brief Burst TA Offset in quarter bits */
+	int16_t		lqual_cb;	/* !< \brief Link quality in centiBel */
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_rts_req {
+	uint8_t		sapi;
+	uint8_t		spare[3];
+	uint32_t	fn;
+	uint16_t	arfcn;
+	uint8_t		trx_nr;
+	uint8_t		ts_nr;
+	uint8_t		block_nr;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_rach_ind {
+	uint8_t		sapi;
+	uint16_t	ra;
+	int16_t		qta;
+	uint32_t	fn;
+	uint16_t	arfcn;
+	uint8_t		is_11bit;
+	uint8_t 	burst_type;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_info_trx {
+	uint16_t	arfcn;
+	uint8_t		pdch_mask;		/* PDCH channels per TS */
+	uint8_t		spare;
+	uint8_t		tsc[8];			/* TSC per channel */
+	uint32_t	hlayer1;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_info_ind {
+	uint32_t	version;
+	uint32_t	flags;
+	struct gsm_pcu_if_info_trx trx[8];	/* TRX infos per BTS */
+	uint8_t		bsic;
+	/* RAI */
+	uint16_t	mcc, mnc, lac, rac;
+	/* NSE */
+	uint16_t	nsei;
+	uint8_t		nse_timer[7];
+	uint8_t		cell_timer[11];
+	/* cell  */
+	uint16_t	cell_id;
+	uint16_t	repeat_time;
+	uint8_t		repeat_count;
+	uint16_t	bvci;
+	uint8_t		t3142;
+	uint8_t		t3169;
+	uint8_t		t3191;
+	uint8_t		t3193_10ms;
+	uint8_t		t3195;
+	uint8_t		n3101;
+	uint8_t		n3103;
+	uint8_t		n3105;
+	uint8_t		cv_countdown;
+	uint16_t	dl_tbf_ext;
+	uint16_t	ul_tbf_ext;
+	uint8_t		initial_cs;
+	uint8_t		initial_mcs;
+	/* NSVC */
+	uint16_t	nsvci[2];
+	uint16_t	local_port[2];
+	uint16_t	remote_port[2];
+	uint32_t	remote_ip[2];
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_act_req {
+	uint8_t		activate;
+	uint8_t		trx_nr;
+	uint8_t		ts_nr;
+	uint8_t		spare;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_time_ind {
+	uint32_t	fn;
+} __attribute__ ((packed));
+
+struct gsm_pcu_if_pag_req {
+	uint8_t		sapi;
+	uint8_t		chan_needed;
+	uint8_t		identity_lv[9];
+} __attribute__ ((packed));
+
+struct gsm_pcu_if {
+	/* context based information */
+	uint8_t		msg_type;	/* message type */
+	uint8_t		bts_nr;		/* bts number */
+	uint8_t		spare[2];
+
+	union {
+		struct gsm_pcu_if_data		data_req;
+		struct gsm_pcu_if_data		data_cnf;
+		struct gsm_pcu_if_data		data_ind;
+		struct gsm_pcu_if_rts_req	rts_req;
+		struct gsm_pcu_if_rach_ind	rach_ind;
+		struct gsm_pcu_if_info_ind	info_ind;
+		struct gsm_pcu_if_act_req	act_req;
+		struct gsm_pcu_if_time_ind	time_ind;
+		struct gsm_pcu_if_pag_req	pag_req;
+	} u;
+} __attribute__ ((packed));
+
+#endif /* _PCUIF_PROTO_H */
diff --git a/openbsc/src/libbsc/pcu_sock.c b/openbsc/src/libbsc/pcu_sock.c
new file mode 100644
index 000000000..62f18a783
--- /dev/null
+++ b/openbsc/src/libbsc/pcu_sock.c
@@ -0,0 +1,918 @@
+/* pcu_sock.c: Connect from PCU via unix domain socket */
+
+/* (C) 2008-2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2009-2012 by Andreas Eversberg <jolly@eversberg.eu>
+ * (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 General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/select.h>
+#include <osmocom/core/socket.h>
+#include <osmo-bts/logging.h>
+#include <osmo-bts/gsm_data.h>
+#include <osmo-bts/pcu_if.h>
+#include <osmo-bts/pcuif_proto.h>
+#include <osmo-bts/bts.h>
+#include <osmo-bts/rsl.h>
+#include <osmo-bts/signal.h>
+#include <osmo-bts/l1sap.h>
+
+uint32_t trx_get_hlayer1(struct gsm_bts_trx *trx);
+
+extern struct gsm_network bts_gsmnet;
+int pcu_direct = 0;
+static int avail_lai = 0, avail_nse = 0, avail_cell = 0, avail_nsvc[2] = {0, 0};
+
+static const char *sapi_string[] = {
+	[PCU_IF_SAPI_RACH] =	"RACH",
+	[PCU_IF_SAPI_AGCH] =	"AGCH",
+	[PCU_IF_SAPI_PCH] =	"PCH",
+	[PCU_IF_SAPI_BCCH] =	"BCCH",
+	[PCU_IF_SAPI_PDTCH] =	"PDTCH",
+	[PCU_IF_SAPI_PRACH] =	"PRACH",
+	[PCU_IF_SAPI_PTCCH] = 	"PTCCH",
+};
+
+static int pcu_sock_send(struct gsm_network *net, struct msgb *msg);
+
+
+static struct gsm_bts_trx *trx_by_nr(struct gsm_bts *bts, uint8_t trx_nr)
+{
+	struct gsm_bts_trx *trx;
+
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		if (trx->nr == trx_nr)
+			return trx;
+	}
+
+	return NULL;
+}
+
+
+/*
+ * PCU messages
+ */
+
+struct msgb *pcu_msgb_alloc(uint8_t msg_type, uint8_t bts_nr)
+{
+	struct msgb *msg;
+	struct gsm_pcu_if *pcu_prim;
+
+	msg = msgb_alloc(sizeof(struct gsm_pcu_if), "pcu_sock_tx");
+	if (!msg)
+		return NULL;
+	msgb_put(msg, sizeof(struct gsm_pcu_if));
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	pcu_prim->msg_type = msg_type; 
+	pcu_prim->bts_nr = bts_nr; 
+
+	return msg;
+}
+
+static bool ts_should_be_pdch(struct gsm_bts_trx_ts *ts) {
+	if (ts->pchan == GSM_PCHAN_PDCH)
+		return true;
+	if (ts->pchan == GSM_PCHAN_TCH_F_PDCH) {
+		/* When we're busy deactivating the PDCH, we first set
+		 * DEACT_PENDING, tell the PCU about it and wait for a
+		 * response. So DEACT_PENDING means "no PDCH" to the PCU.
+		 * Similarly, when we're activating PDCH, we set the
+		 * ACT_PENDING and wait for an activation response from the
+		 * PCU, so ACT_PENDING means "is PDCH". */
+		if (ts->flags & TS_F_PDCH_ACTIVE)
+			return !(ts->flags & TS_F_PDCH_DEACT_PENDING);
+		else
+			return (ts->flags & TS_F_PDCH_ACT_PENDING);
+	}
+	if (ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH) {
+		/*
+		 * When we're busy de-/activating the PDCH, we first set
+		 * ts->dyn.pchan_want, tell the PCU about it and wait for a
+		 * response. So only care about dyn.pchan_want here.
+		 */
+		return ts->dyn.pchan_want == GSM_PCHAN_PDCH;
+	}
+	return false;
+}
+
+int pcu_tx_info_ind(void)
+{
+	struct gsm_network *net = &bts_gsmnet;
+	struct msgb *msg;
+	struct gsm_pcu_if *pcu_prim;
+	struct gsm_pcu_if_info_ind *info_ind;
+	struct gsm_bts *bts;
+	struct gprs_rlc_cfg *rlcc;
+	struct gsm_bts_gprs_nsvc *nsvc;
+	struct gsm_bts_trx *trx;
+	struct gsm_bts_trx_ts *ts;
+	int i, j;
+
+	LOGP(DPCU, LOGL_INFO, "Sending info\n");
+
+	/* FIXME: allow multiple BTS */
+	bts = llist_entry(net->bts_list.next, struct gsm_bts, list);
+	rlcc = &bts->gprs.cell.rlc_cfg;
+
+	msg = pcu_msgb_alloc(PCU_IF_MSG_INFO_IND, bts->nr);
+	if (!msg)
+		return -ENOMEM;
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	info_ind = &pcu_prim->u.info_ind;
+	info_ind->version = PCU_IF_VERSION;
+
+	if (avail_lai && avail_nse && avail_cell && avail_nsvc[0]) {
+		info_ind->flags |= PCU_IF_FLAG_ACTIVE;
+		LOGP(DPCU, LOGL_INFO, "BTS is up\n");
+	} else
+		LOGP(DPCU, LOGL_INFO, "BTS is down\n");
+
+	if (pcu_direct)
+		info_ind->flags |= PCU_IF_FLAG_SYSMO;
+
+	/* RAI */
+	info_ind->mcc = net->mcc;
+	info_ind->mnc = net->mnc;
+	info_ind->lac = bts->location_area_code;
+	info_ind->rac = bts->gprs.rac;
+
+	/* NSE */
+	info_ind->nsei = bts->gprs.nse.nsei;
+	memcpy(info_ind->nse_timer, bts->gprs.nse.timer, 7);
+	memcpy(info_ind->cell_timer, bts->gprs.cell.timer, 11);
+
+	/* cell attributes */
+	info_ind->cell_id = bts->cell_identity;
+	info_ind->repeat_time = rlcc->paging.repeat_time;
+	info_ind->repeat_count = rlcc->paging.repeat_count;
+	info_ind->bvci = bts->gprs.cell.bvci;
+	info_ind->t3142 = rlcc->parameter[RLC_T3142];
+	info_ind->t3169 = rlcc->parameter[RLC_T3169];
+	info_ind->t3191 = rlcc->parameter[RLC_T3191];
+	info_ind->t3193_10ms = rlcc->parameter[RLC_T3193];
+	info_ind->t3195 = rlcc->parameter[RLC_T3195];
+	info_ind->n3101 = rlcc->parameter[RLC_N3101];
+	info_ind->n3103 = rlcc->parameter[RLC_N3103];
+	info_ind->n3105 = rlcc->parameter[RLC_N3105];
+	info_ind->cv_countdown = rlcc->parameter[CV_COUNTDOWN];
+	if (rlcc->cs_mask & (1 << GPRS_CS1))
+		info_ind->flags |= PCU_IF_FLAG_CS1;
+	if (rlcc->cs_mask & (1 << GPRS_CS2))
+		info_ind->flags |= PCU_IF_FLAG_CS2;
+	if (rlcc->cs_mask & (1 << GPRS_CS3))
+		info_ind->flags |= PCU_IF_FLAG_CS3;
+	if (rlcc->cs_mask & (1 << GPRS_CS4))
+		info_ind->flags |= PCU_IF_FLAG_CS4;
+	if (rlcc->cs_mask & (1 << GPRS_MCS1))
+		info_ind->flags |= PCU_IF_FLAG_MCS1;
+	if (rlcc->cs_mask & (1 << GPRS_MCS2))
+		info_ind->flags |= PCU_IF_FLAG_MCS2;
+	if (rlcc->cs_mask & (1 << GPRS_MCS3))
+		info_ind->flags |= PCU_IF_FLAG_MCS3;
+	if (rlcc->cs_mask & (1 << GPRS_MCS4))
+		info_ind->flags |= PCU_IF_FLAG_MCS4;
+	if (rlcc->cs_mask & (1 << GPRS_MCS5))
+		info_ind->flags |= PCU_IF_FLAG_MCS5;
+	if (rlcc->cs_mask & (1 << GPRS_MCS6))
+		info_ind->flags |= PCU_IF_FLAG_MCS6;
+	if (rlcc->cs_mask & (1 << GPRS_MCS7))
+		info_ind->flags |= PCU_IF_FLAG_MCS7;
+	if (rlcc->cs_mask & (1 << GPRS_MCS8))
+		info_ind->flags |= PCU_IF_FLAG_MCS8;
+	if (rlcc->cs_mask & (1 << GPRS_MCS9))
+		info_ind->flags |= PCU_IF_FLAG_MCS9;
+#warning	"isn't dl_tbf_ext wrong?: * 10 and no ntohs"
+	info_ind->dl_tbf_ext = rlcc->parameter[T_DL_TBF_EXT];
+#warning	"isn't ul_tbf_ext wrong?: * 10 and no ntohs"
+	info_ind->ul_tbf_ext = rlcc->parameter[T_UL_TBF_EXT];
+	info_ind->initial_cs = rlcc->initial_cs;
+	info_ind->initial_mcs = rlcc->initial_mcs;
+
+	/* NSVC */
+	for (i = 0; i < 2; i++) {
+		nsvc = &bts->gprs.nsvc[i];
+		info_ind->nsvci[i] = nsvc->nsvci;
+		info_ind->local_port[i] = nsvc->local_port;
+		info_ind->remote_port[i] = nsvc->remote_port;
+		info_ind->remote_ip[i] = nsvc->remote_ip;
+	}
+
+	for (i = 0; i < 8; i++) {
+		trx = trx_by_nr(bts, i);
+		if (!trx)
+			break;
+		info_ind->trx[i].pdch_mask = 0;
+		info_ind->trx[i].arfcn = trx->arfcn;
+		info_ind->trx[i].hlayer1 = trx_get_hlayer1(trx);
+		for (j = 0; j < 8; j++) {
+			ts = &trx->ts[j];
+			if (ts->mo.nm_state.operational == NM_OPSTATE_ENABLED
+			    && ts_should_be_pdch(ts)) {
+				info_ind->trx[i].pdch_mask |= (1 << j);
+				info_ind->trx[i].tsc[j] =
+					(ts->tsc >= 0) ? ts->tsc : bts->bsic & 7;
+				LOGP(DPCU, LOGL_INFO, "trx=%d ts=%d: "
+					"available (tsc=%d arfcn=%d)\n",
+					trx->nr, ts->nr,
+					info_ind->trx[i].tsc[j],
+					info_ind->trx[i].arfcn);
+			}
+		}
+	}
+
+	return pcu_sock_send(net, msg);
+}
+
+static int pcu_if_signal_cb(unsigned int subsys, unsigned int signal,
+	void *hdlr_data, void *signal_data)
+{
+	struct gsm_network *net = &bts_gsmnet;
+	struct gsm_bts_gprs_nsvc *nsvc;
+	struct gsm_bts *bts;
+	struct gsm48_system_information_type_3 *si3;
+	int id;
+
+	if (subsys != SS_GLOBAL)
+		return -EINVAL;
+
+	switch(signal) {
+	case S_NEW_SYSINFO:
+		bts = signal_data;
+		if (!(bts->si_valid & (1 << SYSINFO_TYPE_3)))
+			break;
+		si3 = (struct gsm48_system_information_type_3 *)
+						bts->si_buf[SYSINFO_TYPE_3];
+		net->mcc = ((si3->lai.digits[0] & 0x0f) << 8)
+			| (si3->lai.digits[0] & 0xf0)
+			| (si3->lai.digits[1] & 0x0f);
+		net->mnc = ((si3->lai.digits[2] & 0x0f) << 8)
+			| (si3->lai.digits[2] & 0xf0)
+			| ((si3->lai.digits[1] & 0xf0) >> 4);
+		if ((net->mnc & 0x00f) == 0x00f)
+			net->mnc >>= 4;
+		bts->location_area_code = ntohs(si3->lai.lac);
+		bts->cell_identity = si3->cell_identity;
+		avail_lai = 1;
+		break;
+	case S_NEW_NSE_ATTR:
+		bts = signal_data;
+		avail_nse = 1;
+		break;
+	case S_NEW_CELL_ATTR:
+		bts = signal_data;
+		avail_cell = 1;
+		break;
+	case S_NEW_NSVC_ATTR:
+		nsvc = signal_data;
+		id = nsvc->id;
+		if (id < 0 || id > 1)
+			return -EINVAL;
+		avail_nsvc[id] = 1;
+		break;
+	case S_NEW_OP_STATE:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* If all infos have been received, of if one info is updated after
+	 * all infos have been received, transmit info update. */
+	if (avail_lai && avail_nse && avail_cell && avail_nsvc[0])
+		pcu_tx_info_ind();
+	return 0;
+}
+
+
+int pcu_tx_rts_req(struct gsm_bts_trx_ts *ts, uint8_t is_ptcch, uint32_t fn,
+	uint16_t arfcn, uint8_t block_nr)
+{
+	struct msgb *msg;
+	struct gsm_pcu_if *pcu_prim;
+	struct gsm_pcu_if_rts_req *rts_req;
+	struct gsm_bts *bts = ts->trx->bts;
+
+	LOGP(DPCU, LOGL_DEBUG, "Sending rts request: is_ptcch=%d arfcn=%d "
+		"block=%d\n", is_ptcch, arfcn, block_nr);
+
+	msg = pcu_msgb_alloc(PCU_IF_MSG_RTS_REQ, bts->nr);
+	if (!msg)
+		return -ENOMEM;
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	rts_req = &pcu_prim->u.rts_req;
+
+	rts_req->sapi = (is_ptcch) ? PCU_IF_SAPI_PTCCH : PCU_IF_SAPI_PDTCH;
+	rts_req->fn = fn;
+	rts_req->arfcn = arfcn;
+	rts_req->trx_nr = ts->trx->nr;
+	rts_req->ts_nr = ts->nr;
+	rts_req->block_nr = block_nr;
+
+	return pcu_sock_send(&bts_gsmnet, msg);
+}
+
+int pcu_tx_data_ind(struct gsm_bts_trx_ts *ts, uint8_t is_ptcch, uint32_t fn,
+	uint16_t arfcn, uint8_t block_nr, uint8_t *data, uint8_t len,
+	int8_t rssi, uint16_t ber10k, int16_t bto, int16_t lqual)
+{
+	struct msgb *msg;
+	struct gsm_pcu_if *pcu_prim;
+	struct gsm_pcu_if_data *data_ind;
+	struct gsm_bts *bts = ts->trx->bts;
+
+	LOGP(DPCU, LOGL_DEBUG, "Sending data indication: is_ptcch=%d arfcn=%d "
+		"block=%d data=%s\n", is_ptcch, arfcn, block_nr,
+		osmo_hexdump(data, len));
+
+	msg = pcu_msgb_alloc(PCU_IF_MSG_DATA_IND, bts->nr);
+	if (!msg)
+		return -ENOMEM;
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	data_ind = &pcu_prim->u.data_ind;
+
+	data_ind->sapi = (is_ptcch) ? PCU_IF_SAPI_PTCCH : PCU_IF_SAPI_PDTCH;
+	data_ind->rssi = rssi;
+	data_ind->fn = fn;
+	data_ind->arfcn = arfcn;
+	data_ind->trx_nr = ts->trx->nr;
+	data_ind->ts_nr = ts->nr;
+	data_ind->block_nr = block_nr;
+	data_ind->rssi = rssi;
+	data_ind->ber10k = ber10k;
+	data_ind->ta_offs_qbits = bto;
+	data_ind->lqual_cb = lqual;
+	memcpy(data_ind->data, data, len);
+	data_ind->len = len;
+
+	return pcu_sock_send(&bts_gsmnet, msg);
+}
+
+int pcu_tx_rach_ind(struct gsm_bts *bts, int16_t qta, uint16_t ra, uint32_t fn,
+	uint8_t is_11bit, enum ph_burst_type burst_type)
+{
+	struct msgb *msg;
+	struct gsm_pcu_if *pcu_prim;
+	struct gsm_pcu_if_rach_ind *rach_ind;
+
+	LOGP(DPCU, LOGL_INFO, "Sending RACH indication: qta=%d, ra=%d, "
+		"fn=%d\n", qta, ra, fn);
+
+	msg = pcu_msgb_alloc(PCU_IF_MSG_RACH_IND, bts->nr);
+	if (!msg)
+		return -ENOMEM;
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	rach_ind = &pcu_prim->u.rach_ind;
+
+	rach_ind->sapi = PCU_IF_SAPI_RACH;
+	rach_ind->ra = ra;
+	rach_ind->qta = qta;
+	rach_ind->fn = fn;
+	rach_ind->is_11bit = is_11bit;
+	rach_ind->burst_type = burst_type;
+
+	return pcu_sock_send(&bts_gsmnet, msg);
+}
+
+int pcu_tx_time_ind(uint32_t fn)
+{
+	struct msgb *msg;
+	struct gsm_pcu_if *pcu_prim;
+	struct gsm_pcu_if_time_ind *time_ind;
+	uint8_t fn13 = fn % 13;
+
+	/* omit frame numbers not starting at a MAC block */
+	if (fn13 != 0 && fn13 != 4 && fn13 != 8)
+		return 0;
+
+	msg = pcu_msgb_alloc(PCU_IF_MSG_TIME_IND, 0);
+	if (!msg)
+		return -ENOMEM;
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	time_ind = &pcu_prim->u.time_ind;
+
+	time_ind->fn = fn;
+
+	return pcu_sock_send(&bts_gsmnet, msg);
+}
+
+int pcu_tx_pag_req(const uint8_t *identity_lv, uint8_t chan_needed)
+{
+	struct pcu_sock_state *state = bts_gsmnet.pcu_state;
+	struct msgb *msg;
+	struct gsm_pcu_if *pcu_prim;
+	struct gsm_pcu_if_pag_req *pag_req;
+
+	/* check if identity does not fit: length > sizeof(lv) - 1 */
+	if (identity_lv[0] >= sizeof(pag_req->identity_lv)) {
+		LOGP(DPCU, LOGL_ERROR, "Paging identity too large (%d)\n",
+			identity_lv[0]);
+		return -EINVAL;
+	}
+
+	/* socket not created */
+	if (!state) {
+		LOGP(DPCU, LOGL_DEBUG, "PCU socket not created, ignoring "
+			"paging message\n");
+		return 0;
+	}
+
+	msg = pcu_msgb_alloc(PCU_IF_MSG_PAG_REQ, 0);
+	if (!msg)
+		return -ENOMEM;
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	pag_req = &pcu_prim->u.pag_req;
+
+	pag_req->chan_needed = chan_needed;
+	memcpy(pag_req->identity_lv, identity_lv, identity_lv[0] + 1);
+
+	return pcu_sock_send(&bts_gsmnet, msg);
+}
+
+int pcu_tx_pch_data_cnf(uint32_t fn, uint8_t *data, uint8_t len)
+{
+	struct gsm_network *net = &bts_gsmnet;
+	struct gsm_bts *bts;
+	struct msgb *msg;
+	struct gsm_pcu_if *pcu_prim;
+	struct gsm_pcu_if_data *data_cnf;
+
+	/* FIXME: allow multiple BTS */
+	bts = llist_entry(net->bts_list.next, struct gsm_bts, list);
+
+	LOGP(DPCU, LOGL_INFO, "Sending PCH confirm\n");
+
+	msg = pcu_msgb_alloc(PCU_IF_MSG_DATA_CNF, bts->nr);
+	if (!msg)
+		return -ENOMEM;
+	pcu_prim = (struct gsm_pcu_if *) msg->data;
+	data_cnf = &pcu_prim->u.data_cnf;
+
+	data_cnf->sapi = PCU_IF_SAPI_PCH;
+	data_cnf->fn = fn;
+	memcpy(data_cnf->data, data, len);
+	data_cnf->len = len;
+
+	return pcu_sock_send(&bts_gsmnet, msg);
+}
+
+static int pcu_rx_data_req(struct gsm_bts *bts, uint8_t msg_type,
+	struct gsm_pcu_if_data *data_req)
+{
+	uint8_t is_ptcch;
+	struct gsm_bts_trx *trx;
+	struct gsm_bts_trx_ts *ts;
+	struct msgb *msg;
+	int rc = 0;
+
+	LOGP(DPCU, LOGL_DEBUG, "Data request received: sapi=%s arfcn=%d "
+		"block=%d data=%s\n", sapi_string[data_req->sapi],
+		data_req->arfcn, data_req->block_nr,
+		osmo_hexdump(data_req->data, data_req->len));
+
+	switch (data_req->sapi) {
+	case PCU_IF_SAPI_BCCH:
+		if (data_req->len == 23) {
+			bts->si_valid |= (1 << SYSINFO_TYPE_13);
+			memcpy(bts->si_buf[SYSINFO_TYPE_13], data_req->data,
+				data_req->len);
+		} else {
+			bts->si_valid &= ~(1 << SYSINFO_TYPE_13);
+		}
+		osmo_signal_dispatch(SS_GLOBAL, S_NEW_SYSINFO, bts);
+		break;
+	case PCU_IF_SAPI_PCH:
+		if (msg_type == PCU_IF_MSG_PAG_REQ) {
+			/* FIXME: Add function to schedule paging request.
+			 * This might not be required, if PCU_IF_MSG_DATA_REQ
+			 * is used instead. */
+		} else {
+			struct gsm_bts_role_bts *btsb = bts->role;
+
+			paging_add_imm_ass(btsb->paging_state, data_req->data,
+				data_req->len);
+		}
+		break;
+	case PCU_IF_SAPI_AGCH:
+		msg = msgb_alloc(data_req->len, "pcu_agch");
+		if (!msg) {
+			rc = -ENOMEM;
+			break;
+		}
+		msg->l3h = msgb_put(msg, data_req->len);
+		memcpy(msg->l3h, data_req->data, data_req->len);
+		if (bts_agch_enqueue(bts, msg) < 0) {
+			msgb_free(msg);
+			rc = -EIO;
+		}
+		break;
+	case PCU_IF_SAPI_PDTCH:
+	case PCU_IF_SAPI_PTCCH:
+		trx = trx_by_nr(bts, data_req->trx_nr);
+		if (!trx) {
+			LOGP(DPCU, LOGL_ERROR, "Received PCU data request with "
+				"not existing TRX %d\n", data_req->trx_nr);
+			rc = -EINVAL;
+			break;
+		}
+		ts = &trx->ts[data_req->ts_nr];
+		is_ptcch = (data_req->sapi == PCU_IF_SAPI_PTCCH);
+		rc = l1sap_pdch_req(ts, is_ptcch, data_req->fn, data_req->arfcn,
+			data_req->block_nr, data_req->data, data_req->len);
+		break;
+	default:
+		LOGP(DPCU, LOGL_ERROR, "Received PCU data request with "
+			"unsupported sapi %d\n", data_req->sapi);
+		rc = -EINVAL;
+	}
+
+	return rc;
+}
+
+static int pcu_rx_act_req(struct gsm_bts *bts,
+	struct gsm_pcu_if_act_req *act_req)
+{
+	struct gsm_bts_trx *trx;
+	struct gsm_lchan *lchan;
+
+	LOGP(DPCU, LOGL_INFO, "%s request received: TRX=%d TX=%d\n", 
+		(act_req->activate) ? "Activate" : "Deactivate",
+		act_req->trx_nr, act_req->ts_nr);
+
+	trx = trx_by_nr(bts, act_req->trx_nr);
+	if (!trx || act_req->ts_nr >= 8)
+		return -EINVAL;
+
+	lchan = trx->ts[act_req->ts_nr].lchan;
+	lchan->rel_act_kind = LCHAN_REL_ACT_PCU;
+	if (lchan->type != GSM_LCHAN_PDTCH) {
+		LOGP(DPCU, LOGL_ERROR,
+		     "%s request, but lchan is not of type PDTCH (is %s)\n",
+		     (act_req->activate) ? "Activate" : "Deactivate",
+		     gsm_lchant_name(lchan->type));
+		return -EINVAL;
+	}
+	if (act_req->activate)
+		l1sap_chan_act(trx, gsm_lchan2chan_nr(lchan), NULL);
+	else
+		l1sap_chan_rel(trx, gsm_lchan2chan_nr(lchan));
+
+	return 0;
+}
+
+static int pcu_rx(struct gsm_network *net, uint8_t msg_type,
+	struct gsm_pcu_if *pcu_prim)
+{
+	int rc = 0;
+	struct gsm_bts *bts;
+
+	/* FIXME: allow multiple BTS */
+	bts = llist_entry(net->bts_list.next, struct gsm_bts, list);
+
+	switch (msg_type) {
+	case PCU_IF_MSG_DATA_REQ:
+	case PCU_IF_MSG_PAG_REQ:
+		rc = pcu_rx_data_req(bts, msg_type, &pcu_prim->u.data_req);
+		break;
+	case PCU_IF_MSG_ACT_REQ:
+		rc = pcu_rx_act_req(bts, &pcu_prim->u.act_req);
+		break;
+	default:
+		LOGP(DPCU, LOGL_ERROR, "Received unknwon PCU msg type %d\n",
+			msg_type);
+		rc = -EINVAL;
+	}
+
+	return rc;
+}
+
+/*
+ * PCU socket interface
+ */
+
+struct pcu_sock_state {
+	struct gsm_network *net;
+	struct osmo_fd listen_bfd;	/* fd for listen socket */
+	struct osmo_fd conn_bfd;	/* fd for connection to lcr */
+	struct llist_head upqueue;	/* queue for sending messages */
+};
+
+static int pcu_sock_send(struct gsm_network *net, struct msgb *msg)
+{
+	struct pcu_sock_state *state = net->pcu_state;
+	struct osmo_fd *conn_bfd;
+	struct gsm_pcu_if *pcu_prim = (struct gsm_pcu_if *) msg->data;
+
+	if (!state) {
+		if (pcu_prim->msg_type != PCU_IF_MSG_TIME_IND)
+			LOGP(DPCU, LOGL_INFO, "PCU socket not created, "
+				"dropping message\n");
+		msgb_free(msg);
+		return -EINVAL;
+	}
+	conn_bfd = &state->conn_bfd;
+	if (conn_bfd->fd <= 0) {
+		if (pcu_prim->msg_type != PCU_IF_MSG_TIME_IND)
+			LOGP(DPCU, LOGL_NOTICE, "PCU socket not connected, "
+				"dropping message\n");
+		msgb_free(msg);
+		return -EIO;
+	}
+	msgb_enqueue(&state->upqueue, msg);
+	conn_bfd->when |= BSC_FD_WRITE;
+
+	return 0;
+}
+
+static void pcu_sock_close(struct pcu_sock_state *state)
+{
+	struct osmo_fd *bfd = &state->conn_bfd;
+	struct gsm_bts *bts;
+	struct gsm_bts_trx *trx;
+	struct gsm_bts_trx_ts *ts;
+	int i, j;
+
+	/* FIXME: allow multiple BTS */
+	bts = llist_entry(state->net->bts_list.next, struct gsm_bts, list);
+
+	LOGP(DPCU, LOGL_NOTICE, "PCU socket has LOST connection\n");
+
+	close(bfd->fd);
+	bfd->fd = -1;
+	osmo_fd_unregister(bfd);
+
+	/* re-enable the generation of ACCEPT for new connections */
+	state->listen_bfd.when |= BSC_FD_READ;
+
+#if 0
+	/* remove si13, ... */
+	bts->si_valid &= ~(1 << SYSINFO_TYPE_13);
+	osmo_signal_dispatch(SS_GLOBAL, S_NEW_SYSINFO, bts);
+#endif
+
+	/* release PDCH */
+	for (i = 0; i < 8; i++) {
+		trx = trx_by_nr(bts, i);
+		if (!trx)
+			break;
+		for (j = 0; j < 8; j++) {
+			ts = &trx->ts[j];
+			if (ts->mo.nm_state.operational == NM_OPSTATE_ENABLED
+			 && ts->pchan == GSM_PCHAN_PDCH) {
+				ts->lchan->rel_act_kind = LCHAN_REL_ACT_PCU;
+				l1sap_chan_rel(trx,
+					gsm_lchan2chan_nr(ts->lchan));
+			}
+		}
+	}
+
+	/* flush the queue */
+	while (!llist_empty(&state->upqueue)) {
+		struct msgb *msg = msgb_dequeue(&state->upqueue);
+		msgb_free(msg);
+	}
+}
+
+static int pcu_sock_read(struct osmo_fd *bfd)
+{
+	struct pcu_sock_state *state = (struct pcu_sock_state *)bfd->data;
+	struct gsm_pcu_if *pcu_prim;
+	struct msgb *msg;
+	int rc;
+
+	msg = msgb_alloc(sizeof(*pcu_prim), "pcu_sock_rx");
+	if (!msg)
+		return -ENOMEM;
+
+	pcu_prim = (struct gsm_pcu_if *) msg->tail;
+
+	rc = recv(bfd->fd, msg->tail, msgb_tailroom(msg), 0);
+	if (rc == 0)
+		goto close;
+
+	if (rc < 0) {
+		if (errno == EAGAIN)
+			return 0;
+		goto close;
+	}
+
+	rc = pcu_rx(state->net, pcu_prim->msg_type, pcu_prim);
+
+	/* as we always synchronously process the message in pcu_rx() and
+	 * its callbacks, we can free the message here. */
+	msgb_free(msg);
+
+	return rc;
+
+close:
+	msgb_free(msg);
+	pcu_sock_close(state);
+	return -1;
+}
+
+static int pcu_sock_write(struct osmo_fd *bfd)
+{
+	struct pcu_sock_state *state = bfd->data;
+	int rc;
+
+	while (!llist_empty(&state->upqueue)) {
+		struct msgb *msg, *msg2;
+		struct gsm_pcu_if *pcu_prim;
+
+		/* peek at the beginning of the queue */
+		msg = llist_entry(state->upqueue.next, struct msgb, list);
+		pcu_prim = (struct gsm_pcu_if *)msg->data;
+
+		bfd->when &= ~BSC_FD_WRITE;
+
+		/* bug hunter 8-): maybe someone forgot msgb_put(...) ? */
+		if (!msgb_length(msg)) {
+			LOGP(DPCU, LOGL_ERROR, "message type (%d) with ZERO "
+				"bytes!\n", pcu_prim->msg_type);
+			goto dontsend;
+		}
+
+		/* try to send it over the socket */
+		rc = write(bfd->fd, msgb_data(msg), msgb_length(msg));
+		if (rc == 0)
+			goto close;
+		if (rc < 0) {
+			if (errno == EAGAIN) {
+				bfd->when |= BSC_FD_WRITE;
+				break;
+			}
+			goto close;
+		}
+
+dontsend:
+		/* _after_ we send it, we can deueue */
+		msg2 = msgb_dequeue(&state->upqueue);
+		assert(msg == msg2);
+		msgb_free(msg);
+	}
+	return 0;
+
+close:
+	pcu_sock_close(state);
+
+	return -1;
+}
+
+static int pcu_sock_cb(struct osmo_fd *bfd, unsigned int flags)
+{
+	int rc = 0;
+
+	if (flags & BSC_FD_READ)
+		rc = pcu_sock_read(bfd);
+	if (rc < 0)
+		return rc;
+
+	if (flags & BSC_FD_WRITE)
+		rc = pcu_sock_write(bfd);
+
+	return rc;
+}
+
+/* accept connection comming from PCU */
+static int pcu_sock_accept(struct osmo_fd *bfd, unsigned int flags)
+{
+	struct pcu_sock_state *state = (struct pcu_sock_state *)bfd->data;
+	struct osmo_fd *conn_bfd = &state->conn_bfd;
+	struct sockaddr_un un_addr;
+	socklen_t len;
+	int rc;
+
+	len = sizeof(un_addr);
+	rc = accept(bfd->fd, (struct sockaddr *) &un_addr, &len);
+	if (rc < 0) {
+		LOGP(DPCU, LOGL_ERROR, "Failed to accept a new connection\n");
+		return -1;
+	}
+
+	if (conn_bfd->fd >= 0) {
+		LOGP(DPCU, LOGL_NOTICE, "PCU connects but we already have "
+			"another active connection ?!?\n");
+		/* We already have one PCU connected, this is all we support */
+		state->listen_bfd.when &= ~BSC_FD_READ;
+		close(rc);
+		return 0;
+	}
+
+	conn_bfd->fd = rc;
+	conn_bfd->when = BSC_FD_READ;
+	conn_bfd->cb = pcu_sock_cb;
+	conn_bfd->data = state;
+
+	if (osmo_fd_register(conn_bfd) != 0) {
+		LOGP(DPCU, LOGL_ERROR, "Failed to register new connection "
+			"fd\n");
+		close(conn_bfd->fd);
+		conn_bfd->fd = -1;
+		return -1;
+	}
+
+	LOGP(DPCU, LOGL_NOTICE, "PCU socket connected to external PCU\n");
+
+	/* send current info */
+	pcu_tx_info_ind();
+
+	return 0;
+}
+
+int pcu_sock_init(const char *path)
+{
+	struct pcu_sock_state *state;
+	struct osmo_fd *bfd;
+	int rc;
+
+	state = talloc_zero(NULL, struct pcu_sock_state);
+	if (!state)
+		return -ENOMEM;
+
+	INIT_LLIST_HEAD(&state->upqueue);
+	state->net = &bts_gsmnet;
+	state->conn_bfd.fd = -1;
+
+	bfd = &state->listen_bfd;
+
+	bfd->fd = osmo_sock_unix_init(SOCK_SEQPACKET, 0, path,
+		OSMO_SOCK_F_BIND);
+	if (bfd->fd < 0) {
+		LOGP(DPCU, LOGL_ERROR, "Could not create unix socket: %s\n",
+			strerror(errno));
+		talloc_free(state);
+		return -1;
+	}
+
+	bfd->when = BSC_FD_READ;
+	bfd->cb = pcu_sock_accept;
+	bfd->data = state;
+
+	rc = osmo_fd_register(bfd);
+	if (rc < 0) {
+		LOGP(DPCU, LOGL_ERROR, "Could not register listen fd: %d\n",
+			rc);
+		close(bfd->fd);
+		talloc_free(state);
+		return rc;
+	}
+
+	osmo_signal_register_handler(SS_GLOBAL, pcu_if_signal_cb, NULL);
+
+	bts_gsmnet.pcu_state = state;
+
+	return 0;
+}
+
+void pcu_sock_exit(void)
+{
+	struct pcu_sock_state *state = bts_gsmnet.pcu_state;
+	struct osmo_fd *bfd, *conn_bfd;
+
+	if (!state)
+		return;
+
+	osmo_signal_unregister_handler(SS_GLOBAL, pcu_if_signal_cb, NULL);
+	conn_bfd = &state->conn_bfd;
+	if (conn_bfd->fd > 0)
+		pcu_sock_close(state);
+	bfd = &state->listen_bfd;
+	close(bfd->fd);
+	osmo_fd_unregister(bfd);
+	talloc_free(state);
+	bts_gsmnet.pcu_state = NULL;
+}
+
+bool pcu_connected(void) {
+	struct gsm_network *net = &bts_gsmnet;
+	struct pcu_sock_state *state = net->pcu_state;
+
+	if (!state)
+		return false;
+	if (state->conn_bfd.fd <= 0)
+		return false;
+	return true;
+}