audio: Make the BSC handle the new mr_config request of the BSC API

Handle the mr_config request and set the AMR multirate config for
the given MSC. Initialize the mr_config with the AMR5.9 default we
have been using until now.

openbsc/include/openbsc/bsc_api.h

@@ -34,6 +34,13 @@ struct bsc_api {
 	void (*classmark_chg)(struct gsm_subscriber_connection *conn,
 			      const uint8_t *cm2, uint8_t cm2_len,
 			      const uint8_t *cm3, uint8_t cm3_len);
+
+	/**
+	 * Configure the multirate setting on this channel. If it is
+	 * not implemented AMR5.9 will be used.
+	 */
+	void (*mr_config)(struct gsm_subscriber_connection *conn,
+			  struct gsm48_multi_rate_conf *conf);
 };
 
 int bsc_api_init(struct gsm_network *network, struct bsc_api *api);

openbsc/include/openbsc/osmo_msc_data.h

@@ -26,6 +26,7 @@
 #include "bsc_msc.h"
 
 #include <osmocom/core/timer.h>
+#include <osmocom/gsm/protocol/gsm_04_08.h>
 
 #include <regex.h>
 
@@ -68,6 +69,7 @@ struct osmo_msc_data {
 	int rtp_base;
 
 	/* audio codecs */
+	struct gsm48_multi_rate_conf amr_conf;
 	struct gsm_audio_support **audio_support;
 	int audio_length;
 

openbsc/src/libbsc/bsc_api.c

@@ -155,6 +155,12 @@ static void assignment_t10_timeout(void *_conn)
 static void handle_mr_config(struct gsm_subscriber_connection *conn,
 			     struct gsm_lchan *lchan)
 {
+	struct bsc_api *api;
+	api = conn->bts->network->bsc_api;
+
+	if (api->mr_config)
+		return api->mr_config(conn, &lchan->mr_conf);
+
 	lchan->mr_conf.ver = 1;
 	lchan->mr_conf.icmi = 1;
 	lchan->mr_conf.m5_90 = 1;

openbsc/src/osmo-bsc/osmo_bsc_api.c

@@ -316,6 +316,34 @@ static void bsc_cm_update(struct gsm_subscriber_connection *conn,
 	queue_msg_or_return(resp);
 }
 
+static void bsc_mr_config(struct gsm_subscriber_connection *conn,
+			  struct gsm48_multi_rate_conf *conf)
+{
+	struct osmo_msc_data *msc;
+
+	if (!conn->sccp_con) {
+		LOGP(DMSC, LOGL_ERROR,
+		     "No msc data available on conn %p. Audio will be broken.\n",
+		     conn);
+		return;
+	}
+
+	msc = conn->sccp_con->msc;
+
+	conf->ver = 1;
+	conf->icmi = 1;
+
+	/* maybe gcc see's it is copy of _one_ byte */
+	conf->m4_75 = msc->amr_conf.m4_75;
+	conf->m5_15 = msc->amr_conf.m5_15;
+	conf->m5_90 = msc->amr_conf.m5_90;
+	conf->m6_70 = msc->amr_conf.m6_70;
+	conf->m7_40 = msc->amr_conf.m7_40;
+	conf->m7_95 = msc->amr_conf.m7_95;
+	conf->m10_2 = msc->amr_conf.m10_2;
+	conf->m12_2 = msc->amr_conf.m12_2;
+}
+
 static struct bsc_api bsc_handler = {
 	.sapi_n_reject = bsc_sapi_n_reject,
 	.cipher_mode_compl = bsc_cipher_mode_compl,
@@ -325,6 +353,7 @@ static struct bsc_api bsc_handler = {
 	.assign_fail = bsc_assign_fail,
 	.clear_request = bsc_clear_request,
 	.classmark_chg = bsc_cm_update,
+	.mr_config = bsc_mr_config,
 };
 
 struct bsc_api *osmo_bsc_api()

openbsc/src/osmo-bsc/osmo_bsc_msc.c

@@ -494,5 +494,8 @@ struct osmo_msc_data *osmo_msc_data_alloc(struct gsm_network *net, int nr)
 	msc_data->nr = nr;
 	msc_data->allow_emerg = 1;
 
+	/* Defaults for the audio setup */
+	msc_data->amr_conf.m5_90 = 1;
+
 	return msc_data;
 }