dissolve libbsc: move all to src/osmo-bsc, link .o files

Move all of libbsc/ into osmo-bsc/, and separate/move some implementations to
allow linking from utils/* and ipaccess/* without pulling in unccessary
dependencies.

Some utilities use gsm_network and gsm_bts structs, which already include data
structures for fairly advanced uses. Move initialization that only osmo-bsc
needs into new bsc_network_init() and bsc_bts_alloc_register() functions, so
that the leaner tools can use the old gsm_* versions without the need to link
everything (e.g. handover and lchan alloc code).

In some instances, there need to be stubs if to cut off linking "just before
the RSL level" and prevent dependencies from creeping in.
- abis_rsl_rcvmsg(): the only program currently interpreting RSL messages is
  osmo-bsc, the utils are merely concerned with OML, if at all.
- paging_flush_bts(): ip.access nanobts models call this when the RSL link is
  dropped. Only osmo-bsc actually needs to do anything there.
- on_gsm_ts_init(): the mechanism to trigger timeslot initialization is related
  to OML, while this action to take on init would pull in RSL dependencies.
utils/ and ipaccess/ each have a stubs.c file to implement these stubs. Tests
implement stubs inline where required.

From src/utils/, src/ipaccess/ and tests/*/, link in .o files from osmo-bsc/.
In order for this to work, the osmo-bsc subdir must be built before the other
source trees. (An alternative would be to include the .c files as sources, but
that would re-compile them in every source tree. Not a large burden really, but
unless linking .o files gives problems, let's have the quicker build.)

Minor obvious cleanups creep in with this patch, I will not bother to name them
individually now unless code review asks me to.

Rationale:

1) libbsc has been separate to use it for osmo-nitb and osmo-bsc in the old
openbsc.git. This is no longer required, and spreading over libbsc and osmo-bsc
is distracting.

2) Recently, ridiculous linking requirements have made adding new functions
cumbersome, because libbsc has started depending on osmo-bsc/*.c
implementations: on gscon FSM and bssap functions. For example, neither
bs11_config nor ipaccess-config nor bts_test need handover_cfg or BSSMAP
message composition. It makes no sense to link the entire osmo-bsc to it, nor
do we want to keep adding stubs to each linking realm.

Change-Id: I36a586726f5818121abe54d25654819fc451d3bf

1 files changed, 139 insertions, 0 deletions

diff --git a/src/osmo-bsc/bsc_rll.c b/src/osmo-bsc/bsc_rll.c
new file mode 100644
index 000000000..ebf9b8856
--- /dev/null
+++ b/src/osmo-bsc/bsc_rll.c
@@ -0,0 +1,139 @@
+/* GSM BSC Radio Link Layer API
+ * 3GPP TS 08.58 version 8.6.0 Release 1999 / ETSI TS 100 596 V8.6.0 */
+
+/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ *
+ * 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 <errno.h>
+
+#include <osmocom/bsc/debug.h>
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/bsc/bsc_rll.h>
+#include <osmocom/bsc/gsm_data.h>
+#include <osmocom/bsc/chan_alloc.h>
+#include <osmocom/bsc/abis_rsl.h>
+#include <osmocom/bsc/signal.h>
+
+struct bsc_rll_req {
+	struct llist_head list;
+	struct osmo_timer_list timer;
+
+	struct gsm_lchan *lchan;
+	uint8_t link_id;
+
+	void (*cb)(struct gsm_lchan *lchan, uint8_t link_id,
+		   void *data, enum bsc_rllr_ind);
+	void *data;
+};
+
+/* we only compare C1, C2 and SAPI */
+#define LINKID_MASK	0xC7
+
+static LLIST_HEAD(bsc_rll_reqs);
+
+static void complete_rllr(struct bsc_rll_req *rllr, enum bsc_rllr_ind type)
+{
+	llist_del(&rllr->list);
+	rllr->cb(rllr->lchan, rllr->link_id, rllr->data, type);
+	talloc_free(rllr);
+}
+
+static void timer_cb(void *_rllr)
+{
+	struct bsc_rll_req *rllr = _rllr;
+
+	complete_rllr(rllr, BSC_RLLR_IND_TIMEOUT);
+}
+
+/* establish a RLL connection with given SAPI / priority */
+int rll_establish(struct gsm_lchan *lchan, uint8_t sapi,
+		  void (*cb)(struct gsm_lchan *, uint8_t, void *,
+			     enum bsc_rllr_ind),
+		  void *data)
+{
+	struct bsc_rll_req *rllr = talloc_zero(tall_bsc_ctx, struct bsc_rll_req);
+	uint8_t link_id;
+	if (!rllr)
+		return -ENOMEM;
+
+	link_id = sapi;
+
+	/* If we are a TCH and not in signalling mode, we need to
+	 * indicate that the new RLL connection is to be made on the SACCH */
+	if ((lchan->type == GSM_LCHAN_TCH_F ||
+	     lchan->type == GSM_LCHAN_TCH_H) && sapi != 0)
+		link_id |= 0x40;
+
+	rllr->lchan = lchan;
+	rllr->link_id = link_id;
+	rllr->cb = cb;
+	rllr->data = data;
+
+	llist_add(&rllr->list, &bsc_rll_reqs);
+
+	osmo_timer_setup(&rllr->timer, timer_cb, rllr);
+	osmo_timer_schedule(&rllr->timer, 7, 0);
+
+	/* send the RSL RLL ESTablish REQuest */
+	return rsl_establish_request(rllr->lchan, rllr->link_id);
+}
+
+/* Called from RSL code in case we have received an indication regarding
+ * any RLL link */
+void rll_indication(struct gsm_lchan *lchan, uint8_t link_id, uint8_t type)
+{
+	struct bsc_rll_req *rllr, *rllr2;
+
+	llist_for_each_entry_safe(rllr, rllr2, &bsc_rll_reqs, list) {
+		if (rllr->lchan == lchan &&
+		    (rllr->link_id & LINKID_MASK) == (link_id & LINKID_MASK)) {
+			osmo_timer_del(&rllr->timer);
+			complete_rllr(rllr, type);
+			return;
+		}
+	}
+}
+
+static int rll_lchan_signal(unsigned int subsys, unsigned int signal,
+			    void *handler_data, void *signal_data)
+{
+	struct challoc_signal_data *challoc;
+	struct bsc_rll_req *rllr, *rllr2;
+
+	if (subsys != SS_CHALLOC || signal != S_CHALLOC_FREED)
+		return 0;
+
+	challoc = (struct challoc_signal_data *) signal_data;
+
+	llist_for_each_entry_safe(rllr, rllr2, &bsc_rll_reqs, list) {
+		if (rllr->lchan == challoc->lchan) {
+			osmo_timer_del(&rllr->timer);
+			complete_rllr(rllr, BSC_RLLR_IND_ERR_IND);
+		}
+	}
+
+	return 0;
+}
+
+static __attribute__((constructor)) void on_dso_load_rll(void)
+{
+	osmo_signal_register_handler(SS_CHALLOC, rll_lchan_signal, NULL);
+}