pcu_sock: use PCU_IF_SAPI_AGCH_2 instead PCU_IF_SAPI_AGCH

In PCUIF v.11 we use PCU_IF_SAPI_AGCH_2 exclusively. We use this SAPI
to transfer IMMEDIATE ASSIGNMENT messages for uplink and downlink. One
new feature of PCU_IF_SAPI_AGCH_2 is that the PCU may ask to send a
confirmation when the MAC block is sent.

CAUTION: This patch breaks compatibility to current master osmo-pcu (See
also "Depends")

Related: OS#5927
Depends: osmo-pcu.git I9effdcec1da91a6e2e7a7c41f95d3300ad1bb292
Change-Id: I709c27adaf09a6766cfde4d76d878626d30ebb3c

4 files changed, 41 insertions, 13 deletions

diff --git a/include/osmocom/bsc/pcu_if.h b/include/osmocom/bsc/pcu_if.h
index d2d3444f0..6a07f2e02 100644
--- a/include/osmocom/bsc/pcu_if.h
+++ b/include/osmocom/bsc/pcu_if.h
@@ -24,8 +24,8 @@ void pcu_info_update(struct gsm_bts *bts);
 int pcu_tx_rach_ind(struct gsm_bts *bts, int16_t qta, uint16_t ra, uint32_t fn,
 	uint8_t is_11bit, enum ph_burst_type burst_type);
 
-/* Confirm the sending of an immediate assignment to the pcu */
-int pcu_tx_pch_confirm(struct gsm_bts *bts, uint32_t msg_id);
+/* Confirm the sending of an AGCH or PCH MAC block to the pcu */
+int pcu_tx_data_cnf(struct gsm_bts *bts, uint32_t msg_id, uint8_t sapi);
 
 /* Open connection to PCU */
 int pcu_sock_init(struct gsm_network *net);
diff --git a/include/osmocom/bsc/pcuif_proto.h b/include/osmocom/bsc/pcuif_proto.h
index aa22447e8..cd2a29835 100644
--- a/include/osmocom/bsc/pcuif_proto.h
+++ b/include/osmocom/bsc/pcuif_proto.h
@@ -42,6 +42,7 @@
 #define PCU_IF_SAPI_PRACH	0x06	/* packet random access channel */
 #define PCU_IF_SAPI_PTCCH	0x07	/* packet TA control channel */
 #define PCU_IF_SAPI_PCH_2	0x08	/* assignment on PCH (confirmed using message id) */
+#define PCU_IF_SAPI_AGCH_2	0x09	/* assignment on AGCH (confirmed using message id) */
 
 /* flags */
 #define PCU_IF_FLAG_ACTIVE	(1 << 0)/* BTS is active */
@@ -276,6 +277,18 @@ struct gsm_pcu_if_pch {
 	bool confirm;
 } __attribute__((packed));
 
+/* Struct to send a (confirmed) IMMEDIATE ASSIGNMENT message via AGCH. The struct is sent as a data request
+ * (data_req) under SAPI PCU_IF_SAPI_AGCH_2. */
+struct gsm_pcu_if_agch {
+	/* message id as reference for confirmation */
+	uint32_t msg_id;
+	/* GSM mac-block (with immediate assignment message) */
+	uint8_t data[GSM_MACBLOCK_LEN];
+	/* Set to true in case the receiving end must send a confirmation
+	 * when the MAC block (data) has been sent. */
+	bool confirm;
+} __attribute__((packed));
+
 struct gsm_pcu_if {
 	/* context based information */
 	uint8_t		msg_type;	/* message type */
diff --git a/src/osmo-bsc/abis_rsl.c b/src/osmo-bsc/abis_rsl.c
index 76948c9bd..860e4a249 100644
--- a/src/osmo-bsc/abis_rsl.c
+++ b/src/osmo-bsc/abis_rsl.c
@@ -44,6 +44,7 @@
 #include <osmocom/gsm/rsl.h>
 #include <osmocom/core/talloc.h>
 #include <osmocom/bsc/pcu_if.h>
+#include <osmocom/bsc/pcuif_proto.h>
 #include <osmocom/bsc/gsm_08_08.h>
 #include <osmocom/netif/rtp.h>
 #include <osmocom/core/tdef.h>
@@ -2567,7 +2568,7 @@ static int rsl_rx_ericsson_imm_assign_sent(struct msgb *msg)
 	else {
 		msgb_pull(msg, 1); /* drop previous data to use msg_pull_u32 */
 		msg_id = msgb_pull_u32(msg);
-		pcu_tx_pch_confirm(sign_link->trx->bts, msg_id);
+		pcu_tx_data_cnf(sign_link->trx->bts, msg_id, PCU_IF_SAPI_PCH_2);
 	}
 	return 0;
 }
diff --git a/src/osmo-bsc/pcu_sock.c b/src/osmo-bsc/pcu_sock.c
index 696d5f3a3..dc2b8e9fe 100644
--- a/src/osmo-bsc/pcu_sock.c
+++ b/src/osmo-bsc/pcu_sock.c
@@ -57,6 +57,7 @@ static const char *sapi_string[] = {
 	[PCU_IF_SAPI_PRACH] =	"PRACH",
 	[PCU_IF_SAPI_PTCCH] =	"PTCCH",
 	[PCU_IF_SAPI_PCH_2] =	"PCH_2",
+	[PCU_IF_SAPI_AGCH_2] =	"AGCH_2",
 };
 
 bool pcu_connected(const struct gsm_network *net)
@@ -435,14 +436,14 @@ int pcu_tx_rach_ind(struct gsm_bts *bts, int16_t qta, uint16_t ra, uint32_t fn,
 	return pcu_sock_send(bts->network, msg);
 }
 
-/* Confirm the sending of an immediate assignment to the pcu */
-int pcu_tx_pch_confirm(struct gsm_bts *bts, uint32_t msg_id)
+int pcu_tx_data_cnf(struct gsm_bts *bts, uint32_t msg_id, uint8_t sapi)
 {
 	struct msgb *msg;
 	struct gsm_pcu_if *pcu_prim;
 	struct gsm_pcu_if_data_cnf *data_cnf;
 
-	LOG_BTS(bts, DPCU, LOGL_INFO, "Sending PCH confirm with message id\n");
+	LOGP(DPCU, LOGL_DEBUG, "Sending DATA.cnf: sapi=%s msg_id=%08x\n",
+	     sapi_string[sapi], msg_id);
 
 	msg = pcu_msgb_alloc(PCU_IF_MSG_DATA_CNF_2, bts->nr);
 	if (!msg)
@@ -450,7 +451,7 @@ int pcu_tx_pch_confirm(struct gsm_bts *bts, uint32_t msg_id)
 	pcu_prim = (struct gsm_pcu_if *) msg->data;
 	data_cnf = &pcu_prim->u.data_cnf2;
 
-	data_cnf->sapi = PCU_IF_SAPI_PCH_2;
+	data_cnf->sapi = sapi;
 	data_cnf->msg_id = msg_id;
 
 	return pcu_sock_send(bts->network, msg);
@@ -528,8 +529,9 @@ static int pcu_rx_data_req(struct gsm_bts *bts, uint8_t msg_type,
 {
 	uint8_t pag_grp;
 	int rc = 0;
-	struct gsm_pcu_if_pch *pch;
-	struct gsm48_imm_ass *gsm48_imm_ass;
+	const struct gsm_pcu_if_pch *pch;
+	const struct gsm_pcu_if_agch *agch;
+	const struct gsm48_imm_ass *gsm48_imm_ass;
 
 	LOG_BTS(bts, DPCU, LOGL_DEBUG, "Data request received: sapi=%s arfcn=%d "
 		"block=%d data=%s\n", sapi_string[data_req->sapi],
@@ -537,9 +539,21 @@ static int pcu_rx_data_req(struct gsm_bts *bts, uint8_t msg_type,
 		osmo_hexdump(data_req->data, data_req->len));
 
 	switch (data_req->sapi) {
-	case PCU_IF_SAPI_AGCH:
-		if (rsl_imm_assign_cmd(bts, data_req->len, data_req->data))
-			rc = -EIO;
+	case PCU_IF_SAPI_AGCH_2:
+		if (data_req->len < sizeof(struct gsm_pcu_if_agch)) {
+			LOG_BTS(bts, DPCU, LOGL_ERROR, "Received PCU data request with invalid/small length %d\n",
+				data_req->len);
+			break;
+		}
+
+		agch = (struct gsm_pcu_if_agch *)data_req->data;
+		if (rsl_imm_assign_cmd(bts, GSM_MACBLOCK_LEN, agch->data))
+			return -EIO;
+
+		/* Send the confirmation immediately. This is as accurate as we can get since from this point on the
+		 * BTS hardware is responsible to schedule the sending of the IMMEDIATE ASSIGNMENT */
+		if (agch->confirm)
+			return pcu_tx_data_cnf(bts, agch->msg_id, PCU_IF_SAPI_AGCH_2);
 		break;
 	case PCU_IF_SAPI_PCH_2:
 		if (data_req->len < sizeof(struct gsm_pcu_if_pch)) {
@@ -558,7 +572,7 @@ static int pcu_rx_data_req(struct gsm_bts *bts, uint8_t msg_type,
 		if (pcu_rx_rr_paging_pch(bts, pag_grp, pch))
 			return -EIO;
 		if (pch->confirm)
-			return pcu_tx_pch_confirm(bts, pch->msg_id);
+			return pcu_tx_data_cnf(bts, pch->msg_id, PCU_IF_SAPI_PCH_2);
 		break;
 	default:
 		LOG_BTS(bts, DPCU, LOGL_ERROR, "Received PCU data request with "