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/* 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>
#include <osmocom/bsc/bts.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, bool allow_pchan_switch, bool log)
{
struct gsm_lchan *lchan;
struct gsm_bts_trx_ts *ts;
int j, start, stop, dir;
#define LOGPLCHANALLOC(fmt, args...) \
if (log) \
LOGP(DRLL, LOGL_DEBUG, "looking for lchan %s%s%s%s: " fmt, \
gsm_pchan_name(pchan), \
pchan == as_pchan ? "" : " as ", \
pchan == as_pchan ? "" : gsm_pchan_name(as_pchan), \
((pchan != as_pchan) && !allow_pchan_switch) ? " without pchan switch" : "", \
## 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) {
int lchans_as_pchan;
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, allow_pchan_switch)) {
LOGPLCHANALLOC("%s is not usable as %s%s\n", gsm_ts_and_pchan_name(ts),
gsm_pchan_name(as_pchan),
allow_pchan_switch ? "" : " without pchan switch");
continue;
}
/* TS is (going to be) in desired pchan mode. Go ahead and check for an available lchan. */
lchans_as_pchan = pchan_subslots(as_pchan);
ts_for_n_lchans(lchan, ts, lchans_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, bool log)
{
struct gsm_bts_trx *trx;
struct gsm_lchan *lc;
int allow_pchan_switch;
bool try_pchan_switch;
/* First find an lchan that needs no change in its timeslot pchan mode.
* In particular, this ensures that handover to a dynamic timeslot in TCH/H favors timeslots that are currently
* using only one of two TCH/H, so that we don't switch more dynamic timeslots to TCH/H than necessary.
* For non-dynamic timeslots, it is not necessary to do a second pass with allow_pchan_switch ==
* true, because they never switch anyway. */
try_pchan_switch = (pchan != dyn_as_pchan);
for (allow_pchan_switch = 0; allow_pchan_switch <= (try_pchan_switch ? 1 : 0); allow_pchan_switch++) {
if (bts->chan_alloc_reverse) {
llist_for_each_entry_reverse(trx, &bts->trx_list, list) {
lc = _lc_find_trx(trx, pchan, dyn_as_pchan, (bool)allow_pchan_switch, log);
if (lc)
return lc;
}
} else {
llist_for_each_entry(trx, &bts->trx_list, list) {
lc = _lc_find_trx(trx, pchan, dyn_as_pchan, (bool)allow_pchan_switch, log);
if (lc)
return lc;
}
}
}
return NULL;
}
static struct gsm_lchan *
_lc_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan, bool log)
{
return _lc_dyn_find_bts(bts, pchan, pchan, log);
}
enum gsm_chan_t chan_mode_to_chan_type(enum gsm48_chan_mode chan_mode, enum channel_rate chan_rate)
{
switch (gsm48_chan_mode_to_non_vamos(chan_mode)) {
case GSM48_CMODE_SIGN:
switch (chan_rate) {
case CH_RATE_SDCCH:
return GSM_LCHAN_SDCCH;
case CH_RATE_HALF:
return GSM_LCHAN_TCH_H;
case CH_RATE_FULL:
return GSM_LCHAN_TCH_F;
default:
return GSM_LCHAN_NONE;
}
case GSM48_CMODE_SPEECH_EFR:
/* EFR works over FR channels only */
if (chan_rate != CH_RATE_FULL)
return GSM_LCHAN_NONE;
/* fall through */
case GSM48_CMODE_SPEECH_V1:
case GSM48_CMODE_SPEECH_AMR:
switch (chan_rate) {
case CH_RATE_HALF:
return GSM_LCHAN_TCH_H;
case CH_RATE_FULL:
return GSM_LCHAN_TCH_F;
default:
return GSM_LCHAN_NONE;
}
default:
return GSM_LCHAN_NONE;
}
}
struct gsm_lchan *lchan_select_by_chan_mode(struct gsm_bts *bts,
enum gsm48_chan_mode chan_mode, enum channel_rate chan_rate)
{
enum gsm_chan_t type = chan_mode_to_chan_type(chan_mode, chan_rate);
if (type == GSM_LCHAN_NONE)
return NULL;
return lchan_select_by_type(bts, type);
}
struct gsm_lchan *lchan_avail_by_type(struct gsm_bts *bts, enum gsm_chan_t type, bool log)
{
struct gsm_lchan *lchan = NULL;
enum gsm_phys_chan_config first, first_cbch, second, second_cbch;
if (log)
LOG_BTS(bts, DRLL, LOGL_DEBUG, "lchan_avail_by_type(%s)\n", 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, log);
if (lchan == NULL)
lchan = _lc_find_bts(bts, first_cbch, log);
if (lchan == NULL)
lchan = _lc_find_bts(bts, second, log);
if (lchan == NULL)
lchan = _lc_find_bts(bts, second_cbch, log);
break;
case GSM_LCHAN_TCH_F:
lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_F, log);
/* If we don't have TCH/F available, try dynamic TCH/F_PDCH */
if (!lchan)
lchan = _lc_dyn_find_bts(bts, GSM_PCHAN_TCH_F_PDCH,
GSM_PCHAN_TCH_F, log);
/* 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, log);
break;
case GSM_LCHAN_TCH_H:
lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_H, log);
/* 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, log);
break;
default:
LOG_BTS(bts, DRLL, LOGL_ERROR, "Unknown gsm_chan_t %u\n", type);
}
return lchan;
}
/* 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;
lchan = lchan_avail_by_type(bts, type, true);
LOG_BTS(bts, DRLL, LOGL_DEBUG, "lchan_select_by_type(%s)\n", gsm_lchant_name(type));
if (lchan) {
lchan->type = type;
LOG_LCHAN(lchan, LOGL_INFO, "Selected\n");
} else
LOG_BTS(bts, DRLL, LOGL_NOTICE, "Failed to select %s channel\n",
gsm_lchant_name(type));
return lchan;
}
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