large refactoring: use FSMs for lchans; add inter-BSC HO

Add FSMs:

- timeslot_fsm: handle dynamic timeslots and OML+RSL availability.
- lchan_fsm: handle an individual lchan activation, RTP stream and release,
  signal the appropriate calling FSMs on success, failure, release.
- mgw_endpoint_fsm: handle one entire endpoint with several CI.
- assignment_fsm: BSSMAP Assignment Request.
- handover_fsm: all of intra, inter-MO and inter-MT handover.

Above FSMs absorb large parts of the gscon FSM. The gscon FSM was surpassing
the maximum amount events (32), and it is more logical to treat assignment,
handover and MGW procedures in separate FSMs.

- Add logging macros for each FSM type:
  - LOG_TS()
  - LOG_LCHAN()
  - LOG_MGWEP(), LOG_CI()
  - LOG_ASSIGNMENT()
  - LOG_HO()
  These log with the osmo_fsm_inst where present.
  New style decision: logging without a final newline char is awkward,
  especially for gsmtap logging and when other logs interleave LOGPC() calls;
  we have various cases where the final \n goes missing, and also this invokes
  the log category checking N times instead of once.
  So I decided to make these macros *always* append a newline, but only if
  there is no final newline yet. I hope that the compiler optimizes the
  strlen() of the constant format strings away. Thus I can log with or without
  typing "\n" and always get an \n termination anyway.

General:

- replace osmo_timers, state enums and program-wide osmo_signal_dispatch()
  with dedicated FSM timeouts, states and events.

- introduce a common way to handle Tnnn timers: gsm_timers.h/.c: struct T_def.
  These can be used (with some macro magic) to define a state's timeout once,
  and not make mistakes for each osmo_fsm_inst_state_chg().

Details:

bsc_subscr_conn_fsm.c:

- move most states of this FSM to lchan_fsm, assignment_fsm, handover_fsm and
  mgw_endpoint_fsm.

- There is exactly one state for an ongoing Assignment, with all details
  handled in conn->assignment.fi. The state relies on the assignment_fsm's
  timeout.

- There is one state for an ongoing Handover; except for an incoming Handover
  from a remote BSS, the gscon remains in ST_INIT until the new lchan and conn
  are both established.

- move bssmap_add_lcls_status() to osmo_bsc_lcls.c

abis_rsl.c:

- move all dynamic timeslot logic away into timeslot_fsm. Only keep plain send/receive functions in
  abis_rsl.c

- reduce some rsl functions to merely send a message, rename to "_tx_".
  - rsl_ipacc_mdcx(): add '_tx_' in the name; move parts that change the lchan state out into the
    lchan_fsm, the lchan->abis_ip.* are now set there prior to invoking this function.

- move all timers and error/release handling away into various FSMs.

- tweak ipa_smod_s_for_lchan() and ipa_rtp_pt_for_lchan() to not require an
  lchan passed, but just mode,type that they require. Rename to
  ipacc_speech_mode*() and ipacc_payload_type().

- add rsl_forward_layer3_info, used for inter-BSC HO MO, to just send the RR
  message received during BSSMAP Handover Command.

- move various logging to LOG_LCHAN() in order to log with the lchan FSM instance.
  One drawback is that the lchan FSM is limited to one logging category, i.e. this moves some logging
  from DRR to DRSL. It might actually make sense to combine those categories.

- lose LOGP...LOGPC logging cascades: they are bad for gsmtap logging and for performance.

- handle_classmark_chg(): change logging, move cm2 len check out of the cm3 condition (I hope that's
  correct).

- gsm48_send_ho_cmd(): split off gsm48_make_ho_cmd() which doesn't send right away, so that during
  inter-bsc HO we can make an RR Handover Command to send via the MSC to the remote BSS.

assignment_fsm.c:

- the Chan Mode Modify in case of re-using the same lchan is not implemented
  yet, because this was also missing in the previous implementation (OS#3357).

osmo_bsc_api.c:

- simplify bsc_mr_config() and move to lchan_fsm.c, the only caller; rename to
  lchan_mr_config(). (bsc_mr_config() used to copy the values to mr_bts_lv
  twice, once by member assignment and then again with a memcpy.)

- During handover, we used to copy the MR config from the old lchan. Since we
  may handover between FR and HR, rather set the MR Config anew every time, so
  that FR rates are always available on FR lchans, and never on HR lchans.

Depends: I03ee7ce840ecfa0b6a33358e7385528aabd4873f (libosmocore),
         I1f2918418c38918c5ac70acaa51a47adfca12b5e (libosmocore)
Change-Id: I82e3f918295daa83274a4cf803f046979f284366

1 files changed, 332 insertions, 148 deletions

diff --git a/src/osmo-bsc/gsm_data.c b/src/osmo-bsc/gsm_data.c
index 99438bc3c..3cd3432ea 100644
--- a/src/osmo-bsc/gsm_data.c
+++ b/src/osmo-bsc/gsm_data.c
@@ -25,9 +25,10 @@
 #include <ctype.h>
 #include <stdbool.h>
 #include <netinet/in.h>
+#include <talloc.h>
 
 #include <osmocom/core/linuxlist.h>
-#include <osmocom/core/talloc.h>
+#include <osmocom/core/byteswap.h>
 #include <osmocom/gsm/gsm_utils.h>
 #include <osmocom/gsm/abis_nm.h>
 #include <osmocom/core/statistics.h>
@@ -40,6 +41,9 @@
 #include <osmocom/bsc/abis_nm.h>
 #include <osmocom/bsc/handover_cfg.h>
 #include <osmocom/bsc/gsm_timers.h>
+#include <osmocom/bsc/timeslot_fsm.h>
+#include <osmocom/bsc/lchan_fsm.h>
+#include <osmocom/bsc/mgw_endpoint_fsm.h>
 
 void *tall_bsc_ctx = NULL;
 
@@ -471,7 +475,7 @@ const struct value_string gsm_chreq_descs[] = {
 	{ 0,				NULL }
 };
 
-const struct value_string gsm_pchant_names[13] = {
+const struct value_string gsm_pchant_names[] = {
 	{ GSM_PCHAN_NONE,	"NONE" },
 	{ GSM_PCHAN_CCCH,	"CCCH" },
 	{ GSM_PCHAN_CCCH_SDCCH4,"CCCH+SDCCH4" },
@@ -487,6 +491,22 @@ const struct value_string gsm_pchant_names[13] = {
 	{ 0,			NULL }
 };
 
+const struct value_string gsm_pchan_ids[] = {
+	{ GSM_PCHAN_NONE,	"NONE" },
+	{ GSM_PCHAN_CCCH,	"CCCH" },
+	{ GSM_PCHAN_CCCH_SDCCH4,"CCCH_SDCCH4" },
+	{ GSM_PCHAN_TCH_F,	"TCH_F" },
+	{ GSM_PCHAN_TCH_H,	"TCH_H" },
+	{ GSM_PCHAN_SDCCH8_SACCH8C, "SDCCH8" },
+	{ GSM_PCHAN_PDCH,	"PDCH" },
+	{ GSM_PCHAN_TCH_F_PDCH,	"TCH_F_PDCH" },
+	{ GSM_PCHAN_UNKNOWN,	"UNKNOWN" },
+	{ GSM_PCHAN_CCCH_SDCCH4_CBCH, "CCCH_SDCCH4_CBCH" },
+	{ GSM_PCHAN_SDCCH8_SACCH8C_CBCH, "SDCCH8_CBCH" },
+	{ GSM_PCHAN_TCH_F_TCH_H_PDCH, "TCH_F_TCH_H_PDCH" },
+	{ 0,			NULL }
+};
+
 const struct value_string gsm_pchant_descs[13] = {
 	{ GSM_PCHAN_NONE,	"Physical Channel not configured" },
 	{ GSM_PCHAN_CCCH,	"FCCH + SCH + BCCH + CCCH (Comb. IV)" },
@@ -520,22 +540,6 @@ const char *gsm_lchant_name(enum gsm_chan_t c)
 	return get_value_string(gsm_chan_t_names, c);
 }
 
-static const struct value_string lchan_s_names[] = {
-	{ LCHAN_S_NONE,		"NONE" },
-	{ LCHAN_S_ACT_REQ,	"ACTIVATION REQUESTED" },
-	{ LCHAN_S_ACTIVE,	"ACTIVE" },
-	{ LCHAN_S_INACTIVE,	"INACTIVE" },
-	{ LCHAN_S_REL_REQ,	"RELEASE REQUESTED" },
-	{ LCHAN_S_REL_ERR,	"RELEASE DUE ERROR" },
-	{ LCHAN_S_BROKEN,	"BROKEN UNUSABLE" },
-	{ 0,			NULL }
-};
-
-const char *gsm_lchans_name(enum gsm_lchan_state s)
-{
-	return get_value_string(lchan_s_names, s);
-}
-
 static const struct value_string chreq_names[] = {
 	{ GSM_CHREQ_REASON_EMERG,	"EMERGENCY" },
 	{ GSM_CHREQ_REASON_PAG,		"PAGING" },
@@ -698,13 +702,14 @@ struct gsm_bts_trx *gsm_bts_trx_alloc(struct gsm_bts *bts)
 		struct gsm_bts_trx_ts *ts = &trx->ts[k];
 		int l;
 
+
 		ts->trx = trx;
 		ts->nr = k;
-		ts->pchan = GSM_PCHAN_NONE;
-		ts->dyn.pchan_is = GSM_PCHAN_NONE;
-		ts->dyn.pchan_want = GSM_PCHAN_NONE;
+		ts->pchan_from_config = ts->pchan_on_init = ts->pchan_is = GSM_PCHAN_NONE;
 		ts->tsc = -1;
 
+		ts_fsm_alloc(ts);
+
 		gsm_mo_init(&ts->mo, bts, NM_OC_CHANNEL,
 			    bts->nr, trx->nr, ts->nr);
 
@@ -819,7 +824,7 @@ struct gsm_bts *gsm_bts_alloc(struct gsm_network *net, uint8_t bts_num)
 		talloc_free(bts);
 		return NULL;
 	}
-	bts->c0->ts[0].pchan = GSM_PCHAN_CCCH_SDCCH4;
+	bts->c0->ts[0].pchan_from_config = GSM_PCHAN_CCCH_SDCCH4; /* TODO: really?? */
 
 	bts->rach_b_thresh = -1;
 	bts->rach_ldavg_slots = -1;
@@ -947,49 +952,30 @@ char *gsm_ts_name(const struct gsm_bts_trx_ts *ts)
 /*! Log timeslot number with full pchan information */
 char *gsm_ts_and_pchan_name(const struct gsm_bts_trx_ts *ts)
 {
-	switch (ts->pchan) {
-	case GSM_PCHAN_TCH_F_TCH_H_PDCH:
-		if (ts->dyn.pchan_is == ts->dyn.pchan_want)
-			snprintf(ts2str, sizeof(ts2str),
-				 "(bts=%d,trx=%d,ts=%d,pchan=%s as %s)",
-				 ts->trx->bts->nr, ts->trx->nr, ts->nr,
-				 gsm_pchan_name(ts->pchan),
-				 gsm_pchan_name(ts->dyn.pchan_is));
-		else
-			snprintf(ts2str, sizeof(ts2str),
-				 "(bts=%d,trx=%d,ts=%d,pchan=%s"
-				 " switching %s -> %s)",
-				 ts->trx->bts->nr, ts->trx->nr, ts->nr,
-				 gsm_pchan_name(ts->pchan),
-				 gsm_pchan_name(ts->dyn.pchan_is),
-				 gsm_pchan_name(ts->dyn.pchan_want));
-		break;
-	case GSM_PCHAN_TCH_F_PDCH:
-		if ((ts->flags & TS_F_PDCH_PENDING_MASK) == 0)
-			snprintf(ts2str, sizeof(ts2str),
-				 "(bts=%d,trx=%d,ts=%d,pchan=%s as %s)",
-				 ts->trx->bts->nr, ts->trx->nr, ts->nr,
-				 gsm_pchan_name(ts->pchan),
-				 (ts->flags & TS_F_PDCH_ACTIVE)? "PDCH"
-							       : "TCH/F");
-		else
-			snprintf(ts2str, sizeof(ts2str),
-				 "(bts=%d,trx=%d,ts=%d,pchan=%s"
-				 " switching %s -> %s)",
-				 ts->trx->bts->nr, ts->trx->nr, ts->nr,
-				 gsm_pchan_name(ts->pchan),
-				 (ts->flags & TS_F_PDCH_ACTIVE)? "PDCH"
-							       : "TCH/F",
-				 (ts->flags & TS_F_PDCH_ACT_PENDING)? "PDCH"
-								    : "TCH/F");
-		break;
-	default:
-		snprintf(ts2str, sizeof(ts2str), "(bts=%d,trx=%d,ts=%d,pchan=%s)",
+	if (!ts->fi)
+		snprintf(ts2str, sizeof(ts2str),
+			 "(bts=%d,trx=%d,ts=%d,pchan_from_config=%s, not allocated)",
 			 ts->trx->bts->nr, ts->trx->nr, ts->nr,
-			 gsm_pchan_name(ts->pchan));
-		break;
-	}
-
+			 gsm_pchan_name(ts->pchan_from_config));
+	else if (ts->fi->state == TS_ST_NOT_INITIALIZED)
+		snprintf(ts2str, sizeof(ts2str),
+			 "(bts=%d,trx=%d,ts=%d,pchan_from_config=%s,state=%s)",
+			 ts->trx->bts->nr, ts->trx->nr, ts->nr,
+			 gsm_pchan_name(ts->pchan_from_config),
+			 osmo_fsm_inst_state_name(ts->fi));
+	else if (ts->pchan_is == ts->pchan_on_init)
+		snprintf(ts2str, sizeof(ts2str),
+			 "(bts=%d,trx=%d,ts=%d,pchan=%s,state=%s)",
+			 ts->trx->bts->nr, ts->trx->nr, ts->nr,
+			 gsm_pchan_name(ts->pchan_is),
+			 osmo_fsm_inst_state_name(ts->fi));
+	else
+		snprintf(ts2str, sizeof(ts2str),
+			 "(bts=%d,trx=%d,ts=%d,pchan_on_init=%s,pchan=%s,state=%s)",
+			 ts->trx->bts->nr, ts->trx->nr, ts->nr,
+			 gsm_pchan_name(ts->pchan_on_init),
+			 gsm_pchan_name(ts->pchan_is),
+			 osmo_fsm_inst_state_name(ts->fi));
 	return ts2str;
 }
 
@@ -1207,20 +1193,9 @@ uint8_t gsm_pchan2chan_nr(enum gsm_phys_chan_config pchan,
 
 uint8_t gsm_lchan2chan_nr(const struct gsm_lchan *lchan)
 {
-	enum gsm_phys_chan_config pchan = lchan->ts->pchan;
-	if (pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH)
-		return gsm_lchan_as_pchan2chan_nr(lchan,
-						  lchan->ts->dyn.pchan_is);
-	return gsm_pchan2chan_nr(lchan->ts->pchan, lchan->ts->nr, lchan->nr);
-}
-
-uint8_t gsm_lchan_as_pchan2chan_nr(const struct gsm_lchan *lchan,
-				   enum gsm_phys_chan_config as_pchan)
-{
-	if (lchan->ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH
-	    && as_pchan == GSM_PCHAN_PDCH)
-		return RSL_CHAN_OSMO_PDCH | (lchan->ts->nr & ~RSL_CHAN_NR_MASK);
-	return gsm_pchan2chan_nr(as_pchan, lchan->ts->nr, lchan->nr);
+	/* Note: non-standard Osmocom style dyn TS PDCH mode chan_nr is only used within
+	 * rsl_tx_dyn_ts_pdch_act_deact(). */
+	return gsm_pchan2chan_nr(lchan->ts->pchan_is, lchan->ts->nr, lchan->nr);
 }
 
 /* return the gsm_lchan for the CBCH (if it exists at all) */
@@ -1229,12 +1204,12 @@ struct gsm_lchan *gsm_bts_get_cbch(struct gsm_bts *bts)
 	struct gsm_lchan *lchan = NULL;
 	struct gsm_bts_trx *trx = bts->c0;
 
-	if (trx->ts[0].pchan == GSM_PCHAN_CCCH_SDCCH4_CBCH)
+	if (trx->ts[0].pchan_is == GSM_PCHAN_CCCH_SDCCH4_CBCH)
 		lchan = &trx->ts[0].lchan[2];
 	else {
 		int i;
 		for (i = 0; i < 8; i++) {
-			if (trx->ts[i].pchan == GSM_PCHAN_SDCCH8_SACCH8C_CBCH) {
+			if (trx->ts[i].pchan_is == GSM_PCHAN_SDCCH8_SACCH8C_CBCH) {
 				lchan = &trx->ts[i].lchan[2];
 				break;
 			}
@@ -1252,48 +1227,31 @@ struct gsm_lchan *rsl_lchan_lookup(struct gsm_bts_trx *trx, uint8_t chan_nr,
 	uint8_t cbits = chan_nr >> 3;
 	uint8_t lch_idx;
 	struct gsm_bts_trx_ts *ts = &trx->ts[ts_nr];
-	bool ok = true;
+	bool ok;
 
 	if (rc)
 		*rc = -EINVAL;
 
 	if (cbits == 0x01) {
-		lch_idx = 0;	/* TCH/F */	
-		if (ts->pchan != GSM_PCHAN_TCH_F &&
-		    ts->pchan != GSM_PCHAN_PDCH &&
-		    ts->pchan != GSM_PCHAN_TCH_F_PDCH
-		    && !(ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH
-			 && (ts->dyn.pchan_is == GSM_PCHAN_TCH_F
-			     || ts->dyn.pchan_want == GSM_PCHAN_TCH_F)))
-			ok = false;
+		lch_idx = 0;	/* TCH/F */
+		ok = ts_is_capable_of_pchan(ts, GSM_PCHAN_TCH_F)
+			|| ts->pchan_on_init == GSM_PCHAN_PDCH; /* PDCH? really? */
 	} else if ((cbits & 0x1e) == 0x02) {
 		lch_idx = cbits & 0x1;	/* TCH/H */
-		if (ts->pchan != GSM_PCHAN_TCH_H
-		    && !(ts->pchan == GSM_PCHAN_TCH_F_TCH_H_PDCH
-			 && (ts->dyn.pchan_is == GSM_PCHAN_TCH_H
-			     || ts->dyn.pchan_want == GSM_PCHAN_TCH_H)))
-			ok = false;
+		ok = ts_is_capable_of_pchan(ts, GSM_PCHAN_TCH_H);
 	} else if ((cbits & 0x1c) == 0x04) {
 		lch_idx = cbits & 0x3;	/* SDCCH/4 */
-		if (ts->pchan != GSM_PCHAN_CCCH_SDCCH4 &&
-		    ts->pchan != GSM_PCHAN_CCCH_SDCCH4_CBCH)
-			ok = false;
+		ok = ts_is_capable_of_pchan(ts, GSM_PCHAN_CCCH_SDCCH4);
 	} else if ((cbits & 0x18) == 0x08) {
 		lch_idx = cbits & 0x7;	/* SDCCH/8 */
-		if (ts->pchan != GSM_PCHAN_SDCCH8_SACCH8C &&
-		    ts->pchan != GSM_PCHAN_SDCCH8_SACCH8C_CBCH)
-			ok = false;
+		ok = ts_is_capable_of_pchan(ts, GSM_PCHAN_SDCCH8_SACCH8C);
 	} else if (cbits == 0x10 || cbits == 0x11 || cbits == 0x12) {
-		lch_idx = 0;
-		if (ts->pchan != GSM_PCHAN_CCCH &&
-		    ts->pchan != GSM_PCHAN_CCCH_SDCCH4 &&
-		    ts->pchan != GSM_PCHAN_CCCH_SDCCH4_CBCH)
-			ok = false;
+		lch_idx = 0; /* CCCH? */
+		ok = ts_is_capable_of_pchan(ts, GSM_PCHAN_CCCH);
 		/* FIXME: we should not return first sdcch4 !!! */
 	} else if ((chan_nr & RSL_CHAN_NR_MASK) == RSL_CHAN_OSMO_PDCH) {
 		lch_idx = 0;
-		if (ts->pchan != GSM_PCHAN_TCH_F_TCH_H_PDCH)
-			ok = false;
+		ok = (ts->pchan_on_init == GSM_PCHAN_TCH_F_TCH_H_PDCH);
 	} else
 		return NULL;
 
@@ -1313,33 +1271,18 @@ static const uint8_t subslots_per_pchan[] = {
 	[GSM_PCHAN_SDCCH8_SACCH8C] = 8,
 	[GSM_PCHAN_CCCH_SDCCH4_CBCH] = 4,
 	[GSM_PCHAN_SDCCH8_SACCH8C_CBCH] = 8,
-	/*
-	 * GSM_PCHAN_TCH_F_PDCH and GSM_PCHAN_TCH_F_TCH_H_PDCH should not be
-	 * part of this, those TS are handled according to their dynamic state.
-	 */
+	/* Dyn TS: maximum allowed subslots */
+	[GSM_PCHAN_TCH_F_TCH_H_PDCH] = 2,
+	[GSM_PCHAN_TCH_F_PDCH] = 1,
 };
 
-/*! Return the actual pchan type, also heeding dynamic TS. */
-enum gsm_phys_chan_config ts_pchan(struct gsm_bts_trx_ts *ts)
-{
-	switch (ts->pchan) {
-	case GSM_PCHAN_TCH_F_TCH_H_PDCH:
-		return ts->dyn.pchan_is;
-	case GSM_PCHAN_TCH_F_PDCH:
-		if (ts->flags & TS_F_PDCH_ACTIVE)
-			return GSM_PCHAN_PDCH;
-		else
-			return GSM_PCHAN_TCH_F;
-	default:
-		return ts->pchan;
-	}
-}
-
 /*! According to ts->pchan and possibly ts->dyn_pchan, return the number of
  * logical channels available in the timeslot. */
-uint8_t ts_subslots(struct gsm_bts_trx_ts *ts)
+uint8_t pchan_subslots(enum gsm_phys_chan_config pchan)
 {
-	return subslots_per_pchan[ts_pchan(ts)];
+	if (pchan < 0 || pchan >= ARRAY_SIZE(subslots_per_pchan))
+		return 0;
+	return subslots_per_pchan[pchan];
 }
 
 static bool pchan_is_tch(enum gsm_phys_chan_config pchan)
@@ -1355,7 +1298,7 @@ static bool pchan_is_tch(enum gsm_phys_chan_config pchan)
 
 bool ts_is_tch(struct gsm_bts_trx_ts *ts)
 {
-	return pchan_is_tch(ts_pchan(ts));
+	return pchan_is_tch(ts->pchan_is);
 }
 
 bool trx_is_usable(const struct gsm_bts_trx *trx)
@@ -1370,34 +1313,20 @@ bool trx_is_usable(const struct gsm_bts_trx *trx)
 	return true;
 }
 
-void gsm_trx_mark_all_ts_uninitialized(struct gsm_bts_trx *trx)
+void gsm_trx_all_ts_dispatch(struct gsm_bts_trx *trx, uint32_t ts_ev, void *data)
 {
 	int i;
 	for (i = 0; i < ARRAY_SIZE(trx->ts); i++) {
 		struct gsm_bts_trx_ts *ts = &trx->ts[i];
-		ts->initialized = false;
+		osmo_fsm_inst_dispatch(ts->fi, ts_ev, data);
 	}
 }
 
-void gsm_bts_mark_all_ts_uninitialized(struct gsm_bts *bts)
+void gsm_bts_all_ts_dispatch(struct gsm_bts *bts, uint32_t ts_ev, void *data)
 {
 	struct gsm_bts_trx *trx;
 	llist_for_each_entry(trx, &bts->trx_list, list)
-		gsm_trx_mark_all_ts_uninitialized(trx);
-}
-
-/* Trigger initial timeslot actions iff both OML and RSL are setup. */
-void gsm_ts_check_init(struct gsm_bts_trx_ts *ts)
-{
-	struct gsm_bts *bts = ts->trx->bts;
-	if (bts->model->oml_is_ts_ready
-	    && !bts->model->oml_is_ts_ready(ts))
-		return;
-	if (!ts->trx->rsl_link)
-		return;
-	if (ts->initialized)
-		return;
-	ts->initialized = on_gsm_ts_init(ts);
+		gsm_trx_all_ts_dispatch(trx, ts_ev, data);
 }
 
 void gsm48_lchan2chan_desc(struct gsm48_chan_desc *cd,
@@ -1426,3 +1355,258 @@ bool nm_is_running(const struct gsm_nm_state *s) {
 		(s->availability == 0xff)
 	);
 }
+
+/* determine the logical channel type based on the physical channel type */
+int gsm_lchan_type_by_pchan(enum gsm_phys_chan_config pchan)
+{
+	switch (pchan) {
+	case GSM_PCHAN_TCH_F:
+		return GSM_LCHAN_TCH_F;
+	case GSM_PCHAN_TCH_H:
+		return GSM_LCHAN_TCH_H;
+	case GSM_PCHAN_SDCCH8_SACCH8C:
+	case GSM_PCHAN_SDCCH8_SACCH8C_CBCH:
+	case GSM_PCHAN_CCCH_SDCCH4:
+	case GSM_PCHAN_CCCH_SDCCH4_CBCH:
+		return GSM_LCHAN_SDCCH;
+	default:
+		return -1;
+	}
+}
+
+enum gsm_phys_chan_config gsm_pchan_by_lchan_type(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;
+	}
+}
+
+/* Can the timeslot in principle be used as this PCHAN kind? */
+bool ts_is_capable_of_pchan(struct gsm_bts_trx_ts *ts, enum gsm_phys_chan_config pchan)
+{
+	switch (ts->pchan_on_init) {
+	case GSM_PCHAN_TCH_F_PDCH:
+		switch (pchan) {
+		case GSM_PCHAN_TCH_F:
+		case GSM_PCHAN_PDCH:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_TCH_F_TCH_H_PDCH:
+		switch (pchan) {
+		case GSM_PCHAN_TCH_F:
+		case GSM_PCHAN_TCH_H:
+		case GSM_PCHAN_PDCH:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_CCCH_SDCCH4_CBCH:
+		switch (pchan) {
+		case GSM_PCHAN_CCCH_SDCCH4_CBCH:
+		case GSM_PCHAN_CCCH_SDCCH4:
+		case GSM_PCHAN_CCCH:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_CCCH_SDCCH4:
+		switch (pchan) {
+		case GSM_PCHAN_CCCH_SDCCH4:
+		case GSM_PCHAN_CCCH:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_SDCCH8_SACCH8C_CBCH:
+		switch (pchan) {
+		case GSM_PCHAN_SDCCH8_SACCH8C_CBCH:
+		case GSM_PCHAN_SDCCH8_SACCH8C:
+			return true;
+		default:
+			return false;
+		}
+
+	default:
+		return ts->pchan_on_init == pchan;
+	}
+}
+
+bool ts_is_capable_of_lchant(struct gsm_bts_trx_ts *ts, enum gsm_chan_t type)
+{
+	switch (ts->pchan_on_init) {
+
+	case GSM_PCHAN_TCH_F:
+		switch (type) {
+		case GSM_LCHAN_TCH_F:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_TCH_H:
+		switch (type) {
+		case GSM_LCHAN_TCH_H:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_TCH_F_PDCH:
+		switch (type) {
+		case GSM_LCHAN_TCH_F:
+		case GSM_LCHAN_PDTCH:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_TCH_F_TCH_H_PDCH:
+		switch (type) {
+		case GSM_LCHAN_TCH_F:
+		case GSM_LCHAN_TCH_H:
+		case GSM_LCHAN_PDTCH:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_PDCH:
+		switch (type) {
+		case GSM_LCHAN_PDTCH:
+			return true;
+		default:
+			return false;
+		}
+
+	case GSM_PCHAN_CCCH:
+		switch (type) {
+		case GSM_LCHAN_CCCH:
+			return true;
+		default:
+			return false;
+		}
+		break;
+
+	case GSM_PCHAN_CCCH_SDCCH4_CBCH:
+	case GSM_PCHAN_CCCH_SDCCH4:
+	case GSM_PCHAN_SDCCH8_SACCH8C:
+	case GSM_PCHAN_SDCCH8_SACCH8C_CBCH:
+		switch (type) {
+		case GSM_LCHAN_CCCH:
+		case GSM_LCHAN_SDCCH:
+			return true;
+		default:
+			return false;
+		}
+
+	default:
+		return false;
+	}
+}
+
+static int trx_count_free_ts(struct gsm_bts_trx *trx, enum gsm_phys_chan_config pchan)
+{
+	struct gsm_bts_trx_ts *ts;
+	struct gsm_lchan *lchan;
+	int j;
+	int count = 0;
+
+	if (!trx_is_usable(trx))
+		return 0;
+
+	for (j = 0; j < ARRAY_SIZE(trx->ts); j++) {
+		ts = &trx->ts[j];
+		if (!ts_is_usable(ts))
+			continue;
+
+		if (ts->pchan_is == GSM_PCHAN_PDCH) {
+			/* Dynamic timeslots in PDCH mode will become TCH if needed. */
+			switch (ts->pchan_on_init) {
+			case GSM_PCHAN_TCH_F_PDCH:
+				if (pchan == GSM_PCHAN_TCH_F)
+					count++;
+				continue;
+
+			case GSM_PCHAN_TCH_F_TCH_H_PDCH:
+				if (pchan == GSM_PCHAN_TCH_F)
+					count++;
+				else if (pchan == GSM_PCHAN_TCH_H)
+					count += 2;
+				continue;
+
+			default:
+				/* Not dynamic, not applicable. */
+				continue;
+			}
+		}
+
+		if (ts->pchan_is != pchan)
+			continue;
+
+		ts_for_each_lchan(lchan, ts) {
+			if (lchan_state_is(lchan, LCHAN_ST_UNUSED))
+				count++;
+		}
+	}
+
+	return count;
+}
+
+/* Count number of free TS of given pchan type */
+int bts_count_free_ts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan)
+{
+	struct gsm_bts_trx *trx;
+	int count = 0;
+
+	llist_for_each_entry(trx, &bts->trx_list, list)
+		count += trx_count_free_ts(trx, pchan);
+
+	return count;
+}
+
+bool ts_is_usable(const struct gsm_bts_trx_ts *ts)
+{
+	if (!trx_is_usable(ts->trx)) {
+		LOGP(DRLL, LOGL_DEBUG, "%s not usable\n", gsm_trx_name(ts->trx));
+		return false;
+	}
+
+	if (!ts->fi)
+		return false;
+
+	switch (ts->fi->state) {
+	case TS_ST_NOT_INITIALIZED:
+	case TS_ST_BORKEN:
+		return false;
+	default:
+		break;
+	}
+
+	return true;
+}
+
+const struct value_string lchan_activate_mode_names[] = {
+	OSMO_VALUE_STRING(FOR_NONE),
+	OSMO_VALUE_STRING(FOR_MS_CHANNEL_REQUEST),
+	OSMO_VALUE_STRING(FOR_ASSIGNMENT),
+	OSMO_VALUE_STRING(FOR_HANDOVER),
+	OSMO_VALUE_STRING(FOR_VTY),
+	{}
+};