trxcon/l1ctl.c

/*
 * OsmocomBB <-> SDR connection bridge
 * GSM L1 control interface handlers
 *
 * (C) 2014 by Sylvain Munaut <tnt@246tNt.com>
 * (C) 2016-2017 by Vadim Yanitskiy <axilirator@gmail.com>
 *
 * 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 <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <assert.h>

#include <arpa/inet.h>

#include <osmocom/core/msgb.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/select.h>
#include <osmocom/gsm/gsm_utils.h>
#include <osmocom/gsm/protocol/gsm_08_58.h>

#include "logging.h"
#include "l1ctl_link.h"
#include "l1ctl_proto.h"

#include "trx_if.h"
#include "sched_trx.h"

static const char *arfcn2band_name(uint16_t arfcn)
{
	enum gsm_band band;

	if (gsm_arfcn2band_rc(arfcn, &band) < 0)
		return "(invalid)";

	return gsm_band_name(band);
}

static struct msgb *l1ctl_alloc_msg(uint8_t msg_type)
{
	struct l1ctl_hdr *l1h;
	struct msgb *msg;

	/**
	 * Each L1CTL message gets its own length pushed in front
	 * before sending. This is why we need this small headroom.
	 */
	msg = msgb_alloc_headroom(L1CTL_LENGTH + L1CTL_MSG_LEN_FIELD,
		L1CTL_MSG_LEN_FIELD, "l1ctl_tx_msg");
	if (!msg) {
		LOGP(DL1C, LOGL_ERROR, "Failed to allocate memory\n");
		return NULL;
	}

	msg->l1h = msgb_put(msg, sizeof(*l1h));
	l1h = (struct l1ctl_hdr *) msg->l1h;
	l1h->msg_type = msg_type;

	return msg;
}

int l1ctl_tx_pm_conf(struct l1ctl_link *l1l, uint16_t band_arfcn,
	int dbm, int last)
{
	struct l1ctl_pm_conf *pmc;
	struct msgb *msg;

	msg = l1ctl_alloc_msg(L1CTL_PM_CONF);
	if (!msg)
		return -ENOMEM;

	LOGP(DL1C, LOGL_DEBUG, "Send PM Conf (%s %d = %d dBm)\n",
		arfcn2band_name(band_arfcn),
		band_arfcn &~ ARFCN_FLAG_MASK, dbm);

	pmc = (struct l1ctl_pm_conf *) msgb_put(msg, sizeof(*pmc));
	pmc->band_arfcn = htons(band_arfcn);
	pmc->pm[0] = dbm2rxlev(dbm);
	pmc->pm[1] = 0;

	if (last) {
		struct l1ctl_hdr *l1h = (struct l1ctl_hdr *) msg->l1h;
		l1h->flags |= L1CTL_F_DONE;
	}

	return l1ctl_link_send(l1l, msg);
}

int l1ctl_tx_reset_ind(struct l1ctl_link *l1l, uint8_t type)
{
	struct msgb *msg;
	struct l1ctl_reset *res;

	msg = l1ctl_alloc_msg(L1CTL_RESET_IND);
	if (!msg)
		return -ENOMEM;

	LOGP(DL1C, LOGL_DEBUG, "Send Reset Ind (%u)\n", type);

	res = (struct l1ctl_reset *) msgb_put(msg, sizeof(*res));
	res->type = type;

	return l1ctl_link_send(l1l, msg);
}

int l1ctl_tx_reset_conf(struct l1ctl_link *l1l, uint8_t type)
{
	struct msgb *msg;
	struct l1ctl_reset *res;

	msg = l1ctl_alloc_msg(L1CTL_RESET_CONF);
	if (!msg)
		return -ENOMEM;

	LOGP(DL1C, LOGL_DEBUG, "Send Reset Conf (%u)\n", type);
	res = (struct l1ctl_reset *) msgb_put(msg, sizeof(*res));
	res->type = type;

	return l1ctl_link_send(l1l, msg);
}

static struct l1ctl_info_dl *put_dl_info_hdr(struct msgb *msg, struct l1ctl_info_dl *dl_info)
{
	size_t len = sizeof(struct l1ctl_info_dl);
	struct l1ctl_info_dl *dl = (struct l1ctl_info_dl *) msgb_put(msg, len);

	if (dl_info) /* Copy DL info provided by handler */
		memcpy(dl, dl_info, len);
	else /* Init DL info header */
		memset(dl, 0x00, len);

	return dl;
}

/* Fill in FBSB payload: BSIC and sync result */
static struct l1ctl_fbsb_conf *fbsb_conf_make(struct msgb *msg, uint8_t result, uint8_t bsic)
{
	struct l1ctl_fbsb_conf *conf = (struct l1ctl_fbsb_conf *) msgb_put(msg, sizeof(*conf));

	LOGP(DL1C, LOGL_DEBUG, "Send FBSB Conf (result=%u, bsic=%u)\n", result, bsic);

	conf->result = result;
	conf->bsic = bsic;

	return conf;
}

int l1ctl_tx_fbsb_conf(struct l1ctl_link *l1l, uint8_t result,
	struct l1ctl_info_dl *dl_info, uint8_t bsic)
{
	struct l1ctl_fbsb_conf *conf;
	struct msgb *msg;

	msg = l1ctl_alloc_msg(L1CTL_FBSB_CONF);
	if (msg == NULL)
		return -ENOMEM;

	put_dl_info_hdr(msg, dl_info);
	talloc_free(dl_info);

	conf = fbsb_conf_make(msg, result, bsic);

	/* FIXME: set proper value */
	conf->initial_freq_err = 0;

	/* Ask SCH handler not to send L1CTL_FBSB_CONF anymore */
	l1l->fbsb_conf_sent = true;

	/* Abort FBSB expire timer */
	if (osmo_timer_pending(&l1l->fbsb_timer))
		osmo_timer_del(&l1l->fbsb_timer);

	return l1ctl_link_send(l1l, msg);
}

int l1ctl_tx_ccch_mode_conf(struct l1ctl_link *l1l, uint8_t mode)
{
	struct l1ctl_ccch_mode_conf *conf;
	struct msgb *msg;

	msg = l1ctl_alloc_msg(L1CTL_CCCH_MODE_CONF);
	if (msg == NULL)
		return -ENOMEM;

	conf = (struct l1ctl_ccch_mode_conf *) msgb_put(msg, sizeof(*conf));
	conf->ccch_mode = mode;

	return l1ctl_link_send(l1l, msg);
}

/**
 * Handles both L1CTL_DATA_IND and L1CTL_TRAFFIC_IND.
 */
int l1ctl_tx_dt_ind(struct l1ctl_link *l1l, struct l1ctl_info_dl *data,
	uint8_t *l2, size_t l2_len, bool traffic)
{
	struct msgb *msg;
	uint8_t *msg_l2;

	msg = l1ctl_alloc_msg(traffic ?
		L1CTL_TRAFFIC_IND : L1CTL_DATA_IND);
	if (msg == NULL)
		return -ENOMEM;

	put_dl_info_hdr(msg, data);

	/* Copy the L2 payload if preset */
	if (l2 && l2_len > 0) {
		msg_l2 = (uint8_t *) msgb_put(msg, l2_len);
		memcpy(msg_l2, l2, l2_len);
	}

	/* Put message to upper layers */
	return l1ctl_link_send(l1l, msg);
}

int l1ctl_tx_rach_conf(struct l1ctl_link *l1l,
	uint16_t band_arfcn, uint32_t fn)
{
	struct l1ctl_info_dl *dl;
	struct msgb *msg;

	msg = l1ctl_alloc_msg(L1CTL_RACH_CONF);
	if (msg == NULL)
		return -ENOMEM;

	dl = put_dl_info_hdr(msg, NULL);
	memset(dl, 0x00, sizeof(*dl));

	dl->band_arfcn = htons(band_arfcn);
	dl->frame_nr = htonl(fn);

	return l1ctl_link_send(l1l, msg);
}


/**
 * Handles both L1CTL_DATA_CONF and L1CTL_TRAFFIC_CONF.
 */
int l1ctl_tx_dt_conf(struct l1ctl_link *l1l,
	struct l1ctl_info_dl *data, bool traffic)
{
	struct msgb *msg;

	msg = l1ctl_alloc_msg(traffic ?
		L1CTL_TRAFFIC_CONF : L1CTL_DATA_CONF);
	if (msg == NULL)
		return -ENOMEM;

	/* Copy DL frame header from source message */
	put_dl_info_hdr(msg, data);

	return l1ctl_link_send(l1l, msg);
}

static enum gsm_phys_chan_config l1ctl_ccch_mode2pchan_config(enum ccch_mode mode)
{
	switch (mode) {
	/* TODO: distinguish extended BCCH */
	case CCCH_MODE_NON_COMBINED:
	case CCCH_MODE_NONE:
		return GSM_PCHAN_CCCH;

	case CCCH_MODE_COMBINED:
		return GSM_PCHAN_CCCH_SDCCH4;
	case CCCH_MODE_COMBINED_CBCH:
		return GSM_PCHAN_CCCH_SDCCH4_CBCH;

	default:
		LOGP(DL1C, LOGL_NOTICE, "Undandled CCCH mode (%u), "
			"assuming non-combined configuration\n", mode);
		return GSM_PCHAN_CCCH;
	}
}

/* FBSB expire timer */
static void fbsb_timer_cb(void *data)
{
	struct l1ctl_link *l1l = (struct l1ctl_link *) data;
	struct l1ctl_info_dl *dl;
	struct msgb *msg;

	msg = l1ctl_alloc_msg(L1CTL_FBSB_CONF);
	if (msg == NULL)
		return;

	LOGP(DL1C, LOGL_NOTICE, "FBSB timer fired for ARFCN %u\n", l1l->trx->band_arfcn &~ ARFCN_FLAG_MASK);

	dl = put_dl_info_hdr(msg, NULL);

	/* Fill in current ARFCN */
	dl->band_arfcn = htons(l1l->trx->band_arfcn);

	fbsb_conf_make(msg, 255, 0);

	/* Ask SCH handler not to send L1CTL_FBSB_CONF anymore */
	l1l->fbsb_conf_sent = true;

	l1ctl_link_send(l1l, msg);
}

static int l1ctl_rx_fbsb_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	enum gsm_phys_chan_config ch_config;
	struct l1ctl_fbsb_req *fbsb;
	uint16_t band_arfcn;
	uint16_t timeout;
	int rc = 0;

	fbsb = (struct l1ctl_fbsb_req *) msg->l1h;
	if (msgb_l1len(msg) < sizeof(*fbsb)) {
		LOGP(DL1C, LOGL_ERROR, "MSG too short FBSB Req: %u\n",
			msgb_l1len(msg));
		rc = -EINVAL;
		goto exit;
	}

	ch_config = l1ctl_ccch_mode2pchan_config(fbsb->ccch_mode);
	band_arfcn = ntohs(fbsb->band_arfcn);
	timeout = ntohs(fbsb->timeout);

	LOGP(DL1C, LOGL_NOTICE, "Received FBSB request (%s %d)\n",
		arfcn2band_name(band_arfcn),
		band_arfcn &~ ARFCN_FLAG_MASK);

	/* Reset scheduler and clock counter */
	sched_trx_reset(l1l->trx, true);

	/* Configure a single timeslot */
	sched_trx_configure_ts(l1l->trx, 0, ch_config);

	/* Ask SCH handler to send L1CTL_FBSB_CONF */
	l1l->fbsb_conf_sent = false;

	/* Only if current ARFCN differs */
	if (l1l->trx->band_arfcn != band_arfcn) {
		/* Update current ARFCN */
		l1l->trx->band_arfcn = band_arfcn;

		/* Tune transceiver to required ARFCN */
		trx_if_cmd_rxtune(l1l->trx, band_arfcn);
		trx_if_cmd_txtune(l1l->trx, band_arfcn);
	}

	/* Transceiver might have been powered on before, e.g.
	 * in case of sending L1CTL_FBSB_REQ due to signal loss. */
	if (!l1l->trx->powered_up)
		trx_if_cmd_poweron(l1l->trx);

	trx_if_cmd_sync(l1l->trx);

	/* Start FBSB expire timer */
	l1l->fbsb_timer.data = l1l;
	l1l->fbsb_timer.cb = fbsb_timer_cb;
	LOGP(DL1C, LOGL_INFO, "Starting FBSB timer %u ms\n", timeout * GSM_TDMA_FN_DURATION_uS / 1000);
	osmo_timer_schedule(&l1l->fbsb_timer, 2, timeout * GSM_TDMA_FN_DURATION_uS);

exit:
	msgb_free(msg);
	return rc;
}

static int l1ctl_rx_pm_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	uint16_t band_arfcn_start, band_arfcn_stop;
	struct l1ctl_pm_req *pmr;
	int rc = 0;

	pmr = (struct l1ctl_pm_req *) msg->l1h;
	if (msgb_l1len(msg) < sizeof(*pmr)) {
		LOGP(DL1C, LOGL_ERROR, "MSG too short PM Req: %u\n",
			msgb_l1len(msg));
		rc = -EINVAL;
		goto exit;
	}

	band_arfcn_start = ntohs(pmr->range.band_arfcn_from);
	band_arfcn_stop  = ntohs(pmr->range.band_arfcn_to);

	LOGP(DL1C, LOGL_NOTICE, "Received power measurement "
		"request (%s: %d -> %d)\n",
		arfcn2band_name(band_arfcn_start),
		band_arfcn_start &~ ARFCN_FLAG_MASK,
		band_arfcn_stop &~ ARFCN_FLAG_MASK);

	/* Send measurement request to transceiver */
	rc = trx_if_cmd_measure(l1l->trx, band_arfcn_start, band_arfcn_stop);

exit:
	msgb_free(msg);
	return rc;
}

static int l1ctl_rx_reset_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	struct l1ctl_reset *res;
	int rc = 0;

	res = (struct l1ctl_reset *) msg->l1h;
	if (msgb_l1len(msg) < sizeof(*res)) {
		LOGP(DL1C, LOGL_ERROR, "MSG too short Reset Req: %u\n",
			msgb_l1len(msg));
		rc = -EINVAL;
		goto exit;
	}

	LOGP(DL1C, LOGL_NOTICE, "Received reset request (%u)\n",
		res->type);

	switch (res->type) {
	case L1CTL_RES_T_FULL:
		/* TODO: implement trx_if_reset() */
		trx_if_cmd_poweroff(l1l->trx);
		trx_if_cmd_echo(l1l->trx);

		/* Fall through */
	case L1CTL_RES_T_SCHED:
		sched_trx_reset(l1l->trx, true);
		break;
	default:
		LOGP(DL1C, LOGL_ERROR, "Unknown L1CTL_RESET_REQ type\n");
		goto exit;
	}

	/* Confirm */
	rc = l1ctl_tx_reset_conf(l1l, res->type);

exit:
	msgb_free(msg);
	return rc;
}

static int l1ctl_rx_echo_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	struct l1ctl_hdr *l1h;

	LOGP(DL1C, LOGL_NOTICE, "Recv Echo Req\n");
	LOGP(DL1C, LOGL_NOTICE, "Send Echo Conf\n");

	/* Nothing to do, just send it back */
	l1h = (struct l1ctl_hdr *) msg->l1h;
	l1h->msg_type = L1CTL_ECHO_CONF;
	msg->data = msg->l1h;

	return l1ctl_link_send(l1l, msg);
}

static int l1ctl_rx_ccch_mode_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	enum gsm_phys_chan_config ch_config;
	struct l1ctl_ccch_mode_req *req;
	struct trx_ts *ts;
	int rc = 0;

	req = (struct l1ctl_ccch_mode_req *) msg->l1h;
	if (msgb_l1len(msg) < sizeof(*req)) {
		LOGP(DL1C, LOGL_ERROR, "MSG too short Reset Req: %u\n",
			msgb_l1len(msg));
		rc = -EINVAL;
		goto exit;
	}

	LOGP(DL1C, LOGL_NOTICE, "Received CCCH mode request (%u)\n",
		req->ccch_mode); /* TODO: add value-string for ccch_mode */

	/* Make sure that TS0 is allocated and configured */
	ts = l1l->trx->ts_list[0];
	if (ts == NULL || ts->mf_layout == NULL) {
		LOGP(DL1C, LOGL_ERROR, "TS0 is not configured");
		rc = -EINVAL;
		goto exit;
	}

	/* Choose corresponding channel combination */
	ch_config = l1ctl_ccch_mode2pchan_config(req->ccch_mode);

	/* Do nothing if the current mode matches required */
	if (ts->mf_layout->chan_config != ch_config)
		rc = sched_trx_configure_ts(l1l->trx, 0, ch_config);

	/* Confirm reconfiguration */
	if (!rc)
		rc = l1ctl_tx_ccch_mode_conf(l1l, req->ccch_mode);

exit:
	msgb_free(msg);
	return rc;
}

static int l1ctl_rx_rach_req(struct l1ctl_link *l1l, struct msgb *msg, bool ext)
{
	struct l1ctl_ext_rach_req *ext_req;
	struct l1ctl_rach_req *req;
	struct l1ctl_info_ul *ul;
	struct trx_ts_prim *prim;
	size_t len;
	int rc;

	ul = (struct l1ctl_info_ul *) msg->l1h;

	/* Is it extended (11-bit) RACH or not? */
	if (ext) {
		ext_req = (struct l1ctl_ext_rach_req *) ul->payload;
		ext_req->offset = ntohs(ext_req->offset);
		ext_req->ra11 = ntohs(ext_req->ra11);
		len = sizeof(*ext_req);

		LOGP(DL1C, LOGL_NOTICE, "Received extended (11-bit) RACH request "
			"(offset=%u, synch_seq=%u, ra11=0x%02hx)\n",
			ext_req->offset, ext_req->synch_seq, ext_req->ra11);
	} else {
		req = (struct l1ctl_rach_req *) ul->payload;
		req->offset = ntohs(req->offset);
		len = sizeof(*req);

		LOGP(DL1C, LOGL_NOTICE, "Received regular (8-bit) RACH request "
			"(offset=%u, ra=0x%02x)\n", req->offset, req->ra);
	}

	/* The controlling L1CTL side always does include the UL info header,
	 * but may leave it empty. We assume RACH is on TS0 in this case. */
	if (ul->chan_nr == 0x00) {
		LOGP(DL1C, LOGL_NOTICE, "The UL info header is empty, "
					"assuming RACH is on TS0\n");
		ul->chan_nr = RSL_CHAN_RACH;
	}

	/* Init a new primitive */
	rc = sched_prim_init(l1l->trx, &prim, len, ul->chan_nr, ul->link_id);
	if (rc)
		goto exit;

	/**
	 * Push this primitive to the transmit queue.
	 * Indicated timeslot needs to be configured.
	 */
	rc = sched_prim_push(l1l->trx, prim, ul->chan_nr);
	if (rc) {
		talloc_free(prim);
		goto exit;
	}

	/* Fill in the payload */
	memcpy(prim->payload, ul->payload, len);

exit:
	msgb_free(msg);
	return rc;
}

static int l1ctl_proc_est_req_h0(struct trx_instance *trx, struct l1ctl_h0 *h)
{
	uint16_t band_arfcn;
	int rc = 0;

	band_arfcn = ntohs(h->band_arfcn);

	LOGP(DL1C, LOGL_NOTICE, "L1CTL_DM_EST_REQ indicates a single "
		"ARFCN=%u channel\n", band_arfcn &~ ARFCN_FLAG_MASK);

	/* Do we need to retune? */
	if (trx->band_arfcn == band_arfcn)
		return 0;

	/* Tune transceiver to required ARFCN */
	rc |= trx_if_cmd_rxtune(trx, band_arfcn);
	rc |= trx_if_cmd_txtune(trx, band_arfcn);
	if (rc)
		return rc;

	/* Update current ARFCN */
	trx->band_arfcn = band_arfcn;

	return 0;
}

static int l1ctl_proc_est_req_h1(struct trx_instance *trx, struct l1ctl_h1 *h)
{
	uint16_t ma[64];
	int i, rc;

	LOGP(DL1C, LOGL_NOTICE, "L1CTL_DM_EST_REQ indicates a Frequency "
		"Hopping (hsn=%u, maio=%u, chans=%u) channel\n",
		h->hsn, h->maio, h->n);

	/* No channels?!? */
	if (!h->n) {
		LOGP(DL1C, LOGL_ERROR, "No channels in mobile allocation?!?\n");
		return -EINVAL;
	} else if (h->n > ARRAY_SIZE(ma)) {
		LOGP(DL1C, LOGL_ERROR, "More than 64 channels in mobile allocation?!?\n");
		return -EINVAL;
	}

	/* Convert from network to host byte order */
	for (i = 0; i < h->n; i++)
		ma[i] = ntohs(h->ma[i]);

	/* Forward hopping parameters to TRX */
	rc = trx_if_cmd_setfh(trx, h->hsn, h->maio, ma, h->n);
	if (rc)
		return rc;

	/**
	 * TODO: update the state of trx_instance somehow
	 * in order to indicate that it is in hopping mode...
	 */
	return 0;
}

static int l1ctl_rx_dm_est_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	enum gsm_phys_chan_config config;
	struct l1ctl_dm_est_req *est_req;
	struct l1ctl_info_ul *ul;
	struct trx_ts *ts;
	uint8_t chan_nr, tn;
	int rc;

	ul = (struct l1ctl_info_ul *) msg->l1h;
	est_req = (struct l1ctl_dm_est_req *) ul->payload;

	chan_nr = ul->chan_nr;
	tn = chan_nr & 0x07;

	LOGP(DL1C, LOGL_NOTICE, "Received L1CTL_DM_EST_REQ "
		"(tn=%u, chan_nr=0x%02x, tsc=%u, tch_mode=0x%02x)\n",
		tn, chan_nr, est_req->tsc, est_req->tch_mode);

	/* Determine channel config */
	config = sched_trx_chan_nr2pchan_config(chan_nr);
	if (config == GSM_PCHAN_NONE) {
		LOGP(DL1C, LOGL_ERROR, "Couldn't determine channel config\n");
		rc = -EINVAL;
		goto exit;
	}

	/* Frequency hopping? */
	if (est_req->h)
		rc = l1ctl_proc_est_req_h1(l1l->trx, &est_req->h1);
	else /* Single ARFCN */
		rc = l1ctl_proc_est_req_h0(l1l->trx, &est_req->h0);
	if (rc)
		goto exit;

	/* Update TSC (Training Sequence Code) */
	l1l->trx->tsc = est_req->tsc;

	/* Configure requested TS */
	rc = sched_trx_configure_ts(l1l->trx, tn, config);
	ts = l1l->trx->ts_list[tn];
	if (rc) {
		rc = -EINVAL;
		goto exit;
	}

	/* Deactivate all lchans */
	sched_trx_deactivate_all_lchans(ts);

	/* Activate only requested lchans */
	rc = sched_trx_set_lchans(ts, chan_nr, 1, est_req->tch_mode);
	if (rc) {
		LOGP(DL1C, LOGL_ERROR, "Couldn't activate requested lchans\n");
		rc = -EINVAL;
		goto exit;
	}

exit:
	msgb_free(msg);
	return rc;
}

static int l1ctl_rx_dm_rel_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	LOGP(DL1C, LOGL_NOTICE, "Received L1CTL_DM_REL_REQ, "
		"switching back to CCCH\n");

	/* Reset scheduler */
	sched_trx_reset(l1l->trx, false);

	msgb_free(msg);
	return 0;
}

/**
 * Handles both L1CTL_DATA_REQ and L1CTL_TRAFFIC_REQ.
 */
static int l1ctl_rx_dt_req(struct l1ctl_link *l1l,
	struct msgb *msg, bool traffic)
{
	struct l1ctl_info_ul *ul;
	struct trx_ts_prim *prim;
	uint8_t chan_nr, link_id;
	size_t payload_len;
	int rc;

	/* Extract UL frame header */
	ul = (struct l1ctl_info_ul *) msg->l1h;

	/* Calculate the payload len */
	msg->l2h = ul->payload;
	payload_len = msgb_l2len(msg);

	/* Obtain channel description */
	chan_nr = ul->chan_nr;
	link_id = ul->link_id & 0x40;

	LOGP(DL1D, LOGL_DEBUG, "Recv %s Req (chan_nr=0x%02x, "
		"link_id=0x%02x, len=%zu)\n", traffic ? "TRAFFIC" : "DATA",
		chan_nr, link_id, payload_len);

	/* Init a new primitive */
	rc = sched_prim_init(l1l->trx, &prim, payload_len,
		chan_nr, link_id);
	if (rc)
		goto exit;

	/* Push this primitive to transmit queue */
	rc = sched_prim_push(l1l->trx, prim, chan_nr);
	if (rc) {
		talloc_free(prim);
		goto exit;
	}

	/* Fill in the payload */
	memcpy(prim->payload, ul->payload, payload_len);

exit:
	msgb_free(msg);
	return rc;
}

static int l1ctl_rx_param_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	struct l1ctl_par_req *par_req;
	struct l1ctl_info_ul *ul;

	ul = (struct l1ctl_info_ul *) msg->l1h;
	par_req = (struct l1ctl_par_req *) ul->payload;

	LOGP(DL1C, LOGL_NOTICE, "Received L1CTL_PARAM_REQ "
		"(ta=%d, tx_power=%u)\n", par_req->ta, par_req->tx_power);

	/* Instruct TRX to use new TA value */
	if (l1l->trx->ta != par_req->ta) {
		trx_if_cmd_setta(l1l->trx, par_req->ta);
		l1l->trx->ta = par_req->ta;
	}

	l1l->trx->tx_power = par_req->tx_power;

	msgb_free(msg);
	return 0;
}

static int l1ctl_rx_tch_mode_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	struct l1ctl_tch_mode_req *req;
	struct trx_lchan_state *lchan;
	struct trx_ts *ts;
	int i;

	req = (struct l1ctl_tch_mode_req *) msg->l1h;

	LOGP(DL1C, LOGL_NOTICE, "Received L1CTL_TCH_MODE_REQ "
		"(tch_mode=%u, audio_mode=%u)\n", req->tch_mode, req->audio_mode);

	/* Iterate over timeslot list */
	for (i = 0; i < TRX_TS_COUNT; i++) {
		/* Timeslot is not allocated */
		ts = l1l->trx->ts_list[i];
		if (ts == NULL)
			continue;

		/* Timeslot is not configured */
		if (ts->mf_layout == NULL)
			continue;

		/* Iterate over all allocated lchans */
		llist_for_each_entry(lchan, &ts->lchans, list) {
			/* Omit inactive channels */
			if (!lchan->active)
				continue;

			/* Set TCH mode */
			lchan->tch_mode = req->tch_mode;
		}
	}

	/* TODO: do we need to care about audio_mode? */

	/* Re-use the original message as confirmation */
	struct l1ctl_hdr *l1h = (struct l1ctl_hdr *) msg->data;
	l1h->msg_type = L1CTL_TCH_MODE_CONF;

	return l1ctl_link_send(l1l, msg);
}

static int l1ctl_rx_crypto_req(struct l1ctl_link *l1l, struct msgb *msg)
{
	struct l1ctl_crypto_req *req;
	struct l1ctl_info_ul *ul;
	struct trx_ts *ts;
	uint8_t tn;
	int rc = 0;

	ul = (struct l1ctl_info_ul *) msg->l1h;
	req = (struct l1ctl_crypto_req *) ul->payload;

	LOGP(DL1C, LOGL_NOTICE, "L1CTL_CRYPTO_REQ (algo=A5/%u, key_len=%u)\n",
		req->algo, req->key_len);

	/* Determine TS index */
	tn = ul->chan_nr & 0x7;

	/* Make sure that required TS is allocated and configured */
	ts = l1l->trx->ts_list[tn];
	if (ts == NULL || ts->mf_layout == NULL) {
		LOGP(DL1C, LOGL_ERROR, "TS %u is not configured\n", tn);
		rc = -EINVAL;
		goto exit;
	}

	/* Poke scheduler */
	rc = sched_trx_start_ciphering(ts, req->algo, req->key, req->key_len);
	if (rc) {
		LOGP(DL1C, LOGL_ERROR, "Couldn't configure ciphering\n");
		rc = -EINVAL;
		goto exit;
	}

exit:
	msgb_free(msg);
	return rc;
}

int l1ctl_rx_cb(struct l1ctl_link *l1l, struct msgb *msg)
{
	struct l1ctl_hdr *l1h;

	l1h = (struct l1ctl_hdr *) msg->l1h;
	msg->l1h = l1h->data;

	switch (l1h->msg_type) {
	case L1CTL_FBSB_REQ:
		return l1ctl_rx_fbsb_req(l1l, msg);
	case L1CTL_PM_REQ:
		return l1ctl_rx_pm_req(l1l, msg);
	case L1CTL_RESET_REQ:
		return l1ctl_rx_reset_req(l1l, msg);
	case L1CTL_ECHO_REQ:
		return l1ctl_rx_echo_req(l1l, msg);
	case L1CTL_CCCH_MODE_REQ:
		return l1ctl_rx_ccch_mode_req(l1l, msg);
	case L1CTL_RACH_REQ:
		return l1ctl_rx_rach_req(l1l, msg, false);
	case L1CTL_EXT_RACH_REQ:
		return l1ctl_rx_rach_req(l1l, msg, true);
	case L1CTL_DM_EST_REQ:
		return l1ctl_rx_dm_est_req(l1l, msg);
	case L1CTL_DM_REL_REQ:
		return l1ctl_rx_dm_rel_req(l1l, msg);
	case L1CTL_DATA_REQ:
		return l1ctl_rx_dt_req(l1l, msg, false);
	case L1CTL_TRAFFIC_REQ:
		return l1ctl_rx_dt_req(l1l, msg, true);
	case L1CTL_PARAM_REQ:
		return l1ctl_rx_param_req(l1l, msg);
	case L1CTL_TCH_MODE_REQ:
		return l1ctl_rx_tch_mode_req(l1l, msg);
	case L1CTL_CRYPTO_REQ:
		return l1ctl_rx_crypto_req(l1l, msg);

	/* Not (yet) handled messages */
	case L1CTL_NEIGH_PM_REQ:
	case L1CTL_DATA_TBF_REQ:
	case L1CTL_TBF_CFG_REQ:
	case L1CTL_DM_FREQ_REQ:
	case L1CTL_SIM_REQ:
		LOGP(DL1C, LOGL_NOTICE, "Ignoring unsupported message "
			"(type=%u)\n", l1h->msg_type);
		msgb_free(msg);
		return -ENOTSUP;
	default:
		LOGP(DL1C, LOGL_ERROR, "Unknown MSG type %u: %s\n", l1h->msg_type,
			osmo_hexdump(msgb_data(msg), msgb_length(msg)));
		msgb_free(msg);
		return -EINVAL;
	}
}

void l1ctl_shutdown_cb(struct l1ctl_link *l1l)
{
	/* Abort FBSB expire timer */
	if (osmo_timer_pending(&l1l->fbsb_timer))
		osmo_timer_del(&l1l->fbsb_timer);
}