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-rw-r--r--src/osmo-bsc/lchan_select.c260
1 files changed, 260 insertions, 0 deletions
diff --git a/src/osmo-bsc/lchan_select.c b/src/osmo-bsc/lchan_select.c
new file mode 100644
index 000000000..742c7de82
--- /dev/null
+++ b/src/osmo-bsc/lchan_select.c
@@ -0,0 +1,260 @@
+/* Select a suitable lchan from a given cell.
+ *
+ * (C) 2008 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2008, 2009 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2018 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * 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 <osmocom/bsc/debug.h>
+
+#include <osmocom/bsc/gsm_data.h>
+#include <osmocom/bsc/timeslot_fsm.h>
+#include <osmocom/bsc/lchan_fsm.h>
+
+#include <osmocom/bsc/lchan_select.h>
+
+static struct gsm_lchan *
+_lc_find_trx(struct gsm_bts_trx *trx, enum gsm_phys_chan_config pchan,
+ enum gsm_phys_chan_config as_pchan)
+{
+ struct gsm_lchan *lchan;
+ struct gsm_bts_trx_ts *ts;
+ int j, start, stop, dir;
+
+#define LOGPLCHANALLOC(fmt, args...) \
+ LOGP(DRLL, LOGL_DEBUG, "looking for lchan %s%s%s: " fmt, \
+ gsm_pchan_name(pchan), \
+ pchan == as_pchan ? "" : " as ", \
+ pchan == as_pchan ? "" : gsm_pchan_name(as_pchan), ## args)
+
+ if (!trx_is_usable(trx)) {
+ LOGPLCHANALLOC("%s trx not usable\n", gsm_trx_name(trx));
+ return NULL;
+ }
+
+ if (trx->bts->chan_alloc_reverse) {
+ /* check TS 7..0 */
+ start = 7;
+ stop = -1;
+ dir = -1;
+ } else {
+ /* check TS 0..7 */
+ start = 0;
+ stop = 8;
+ dir = 1;
+ }
+
+ for (j = start; j != stop; j += dir) {
+ ts = &trx->ts[j];
+ if (!ts_is_usable(ts))
+ continue;
+ /* The caller first selects what kind of TS to search in, e.g. looking for exact
+ * GSM_PCHAN_TCH_F, or maybe among dynamic GSM_PCHAN_TCH_F_TCH_H_PDCH... */
+ if (ts->pchan_on_init != pchan) {
+ LOGPLCHANALLOC("%s is != %s\n", gsm_ts_and_pchan_name(ts),
+ gsm_pchan_name(pchan));
+ continue;
+ }
+ /* Next, is this timeslot in or can it be switched to the pchan we want to use it for? */
+ if (!ts_usable_as_pchan(ts, as_pchan)) {
+ LOGPLCHANALLOC("%s is not usable as %s\n", gsm_ts_and_pchan_name(ts),
+ gsm_pchan_name(as_pchan));
+ continue;
+ }
+
+ /* TS is (going to be) in desired pchan mode. Go ahead and check for an available lchan. */
+ ts_as_pchan_for_each_lchan(lchan, ts, as_pchan) {
+ if (lchan->fi->state == LCHAN_ST_UNUSED) {
+ LOGPLCHANALLOC("%s ss=%d is available%s\n",
+ gsm_ts_and_pchan_name(ts), lchan->nr,
+ ts->pchan_is != as_pchan ? " after dyn PCHAN change" : "");
+ return lchan;
+ }
+ LOGPLCHANALLOC("%s ss=%d in type=%s,state=%s not suitable\n",
+ gsm_ts_and_pchan_name(ts), lchan->nr,
+ gsm_lchant_name(lchan->type),
+ osmo_fsm_inst_state_name(lchan->fi));
+ }
+ }
+
+ return NULL;
+#undef LOGPLCHANALLOC
+}
+
+static struct gsm_lchan *
+_lc_dyn_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan,
+ enum gsm_phys_chan_config dyn_as_pchan)
+{
+ struct gsm_bts_trx *trx;
+ struct gsm_lchan *lc;
+
+ if (bts->chan_alloc_reverse) {
+ llist_for_each_entry_reverse(trx, &bts->trx_list, list) {
+ lc = _lc_find_trx(trx, pchan, dyn_as_pchan);
+ if (lc)
+ return lc;
+ }
+ } else {
+ llist_for_each_entry(trx, &bts->trx_list, list) {
+ lc = _lc_find_trx(trx, pchan, dyn_as_pchan);
+ if (lc)
+ return lc;
+ }
+ }
+
+ return NULL;
+}
+
+static struct gsm_lchan *
+_lc_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan)
+{
+ return _lc_dyn_find_bts(bts, pchan, pchan);
+}
+
+struct gsm_lchan *lchan_select_by_chan_mode(struct gsm_bts *bts,
+ enum gsm48_chan_mode chan_mode, bool full_rate)
+{
+ enum gsm_chan_t type;
+
+ switch (chan_mode) {
+ case GSM48_CMODE_SIGN:
+ type = GSM_LCHAN_SDCCH;
+ break;
+ case GSM48_CMODE_SPEECH_V1:
+ case GSM48_CMODE_SPEECH_EFR:
+ case GSM48_CMODE_SPEECH_AMR:
+ type = full_rate ? GSM_LCHAN_TCH_F : GSM_LCHAN_TCH_H;
+ break;
+ default:
+ return NULL;
+ }
+
+ return lchan_select_by_type(bts, type);
+}
+
+/* Return a matching lchan from a specific BTS that is currently available. The next logical step is
+ * lchan_activate() on it, which would possibly cause dynamic timeslot pchan switching, taken care of by
+ * the lchan and timeslot FSMs. */
+struct gsm_lchan *lchan_select_by_type(struct gsm_bts *bts, enum gsm_chan_t type)
+{
+ struct gsm_lchan *lchan = NULL;
+ enum gsm_phys_chan_config first, first_cbch, second, second_cbch;
+
+ LOGP(DRLL, LOGL_DEBUG, "(bts=%d) lchan_select_by_type(%s)\n", bts->nr, gsm_lchant_name(type));
+
+ switch (type) {
+ case GSM_LCHAN_SDCCH:
+ if (bts->chan_alloc_reverse) {
+ first = GSM_PCHAN_SDCCH8_SACCH8C;
+ first_cbch = GSM_PCHAN_SDCCH8_SACCH8C_CBCH;
+ second = GSM_PCHAN_CCCH_SDCCH4;
+ second_cbch = GSM_PCHAN_CCCH_SDCCH4_CBCH;
+ } else {
+ first = GSM_PCHAN_CCCH_SDCCH4;
+ first_cbch = GSM_PCHAN_CCCH_SDCCH4_CBCH;
+ second = GSM_PCHAN_SDCCH8_SACCH8C;
+ second_cbch = GSM_PCHAN_SDCCH8_SACCH8C_CBCH;
+ }
+
+ lchan = _lc_find_bts(bts, first);
+ if (lchan == NULL)
+ lchan = _lc_find_bts(bts, first_cbch);
+ if (lchan == NULL)
+ lchan = _lc_find_bts(bts, second);
+ if (lchan == NULL)
+ lchan = _lc_find_bts(bts, second_cbch);
+ break;
+ case GSM_LCHAN_TCH_F:
+ lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_F);
+ /* If we don't have TCH/F available, fall-back to TCH/H */
+ if (!lchan) {
+ lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_H);
+ if (lchan)
+ type = GSM_LCHAN_TCH_H;
+ }
+ /* If we don't have TCH/H either, try dynamic TCH/F_PDCH */
+ if (!lchan) {
+ lchan = _lc_dyn_find_bts(bts, GSM_PCHAN_TCH_F_PDCH,
+ GSM_PCHAN_TCH_F);
+ /* TCH/F_PDCH used as TCH/F -- here, type is already
+ * set to GSM_LCHAN_TCH_F, but for clarity's sake... */
+ if (lchan)
+ type = GSM_LCHAN_TCH_F;
+ }
+
+ /* Try fully dynamic TCH/F_TCH/H_PDCH as TCH/F... */
+ if (!lchan && bts->network->dyn_ts_allow_tch_f) {
+ lchan = _lc_dyn_find_bts(bts,
+ GSM_PCHAN_TCH_F_TCH_H_PDCH,
+ GSM_PCHAN_TCH_F);
+ if (lchan)
+ type = GSM_LCHAN_TCH_F;
+ }
+ /* ...and as TCH/H. */
+ if (!lchan) {
+ lchan = _lc_dyn_find_bts(bts,
+ GSM_PCHAN_TCH_F_TCH_H_PDCH,
+ GSM_PCHAN_TCH_H);
+ if (lchan)
+ type = GSM_LCHAN_TCH_H;
+ }
+ break;
+ case GSM_LCHAN_TCH_H:
+ lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_H);
+ /* If we don't have TCH/H available, fall-back to TCH/F */
+ if (!lchan) {
+ lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_F);
+ if (lchan)
+ type = GSM_LCHAN_TCH_F;
+ }
+ /* No dedicated TCH/x available -- try fully dynamic
+ * TCH/F_TCH/H_PDCH */
+ if (!lchan) {
+ lchan = _lc_dyn_find_bts(bts,
+ GSM_PCHAN_TCH_F_TCH_H_PDCH,
+ GSM_PCHAN_TCH_H);
+ if (lchan)
+ type = GSM_LCHAN_TCH_H;
+ }
+ /*
+ * No need to check TCH/F_TCH/H_PDCH channels for TCH/F:
+ * if no TCH/H was available, neither will be TCH/F.
+ */
+ /* If we don't have TCH/F either, try dynamic TCH/F_PDCH */
+ if (!lchan) {
+ lchan = _lc_dyn_find_bts(bts, GSM_PCHAN_TCH_F_PDCH,
+ GSM_PCHAN_TCH_F);
+ if (lchan)
+ type = GSM_LCHAN_TCH_F;
+ }
+ break;
+ default:
+ LOGP(DRLL, LOGL_ERROR, "Unknown gsm_chan_t %u\n", type);
+ }
+
+ if (lchan) {
+ lchan->type = type;
+ LOG_LCHAN(lchan, LOGL_INFO, "Selected\n");
+ } else
+ LOGP(DRLL, LOGL_ERROR, "(bts=%d) Failed to select %s channel\n",
+ bts->nr, gsm_lchant_name(type));
+
+ return lchan;
+}
+
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