BSSMAP RESET: generalize a_reset FSM

Separate the a_reset FSM implementation from BSSMAP and MSC specifics, so that
it can be re-used on the Lb interface.

Move the FSM implementation to bssmap_reset.c and tweak, to match common practices we
have generally established in our osmo_fsm implementations.

Keep a_reset.h and a_reset.c and redirect to bssmap_reset.c.

A difficulty is setting a proper logging category: the FSM definition allows
only one fixed logging category for FSM state transitions and events. Ideally,
the BSSMAP reset fsm would log on DMSC, and the BSSMAP-LE reset fsm would log
on DLCS. Since that is not possible, introduce a separate DRESET logging
category. This in fact matches an item on my wishlist, because if a given MSC
is configured but currently not connected, the previous RESET FSM would
continuously "spam" log LOGL_NOTICE messages indicating that it is resending
RESET, and I often want to silence those messages without silencing the entire
DMSC category. This is now easily possible by setting DRESET logging to
LOGL_ERROR. There is additional "link up" / "link lost" logging on DMSC, so all
interesting info is still visible on DMSC.

Change-Id: Ib3c3a163186c40a93be0dea666230431172136df

1 files changed, 27 insertions, 0 deletions

diff --git a/include/osmocom/bsc/bssmap_reset.h b/include/osmocom/bsc/bssmap_reset.h
new file mode 100644
index 000000000..ba6425701
--- /dev/null
+++ b/include/osmocom/bsc/bssmap_reset.h
@@ -0,0 +1,27 @@
+/* Manage RESET and disconnection detection on BSSMAP and BSSMAP-LE */
+#pragma once
+
+enum bssmap_reset_fsm_event {
+	BSSMAP_RESET_EV_RX_RESET_ACK,
+	BSSMAP_RESET_EV_CONN_CFM_SUCCESS,
+	BSSMAP_RESET_EV_CONN_CFM_FAILURE,
+};
+
+struct bssmap_reset_cfg {
+	int conn_cfm_failure_threshold;
+	struct {
+		void (*tx_reset)(void *data);
+		void (*link_up)(void *data);
+		void (*link_lost)(void *data);
+	} ops;
+	void *data;
+};
+
+struct bssmap_reset {
+	struct osmo_fsm_inst *fi;
+	struct bssmap_reset_cfg cfg;
+	int conn_cfm_failures;
+};
+
+struct bssmap_reset *bssmap_reset_alloc(void *ctx, const char *label, const struct bssmap_reset_cfg *cfg);
+bool bssmap_reset_is_conn_ready(const struct bssmap_reset *bssmap_reset);