host/trxcon: integrate osmo-fsm framework

This change introduces the following state machines:

  - trxcon_app_fsm - main application state machine.

    This state machine handles different events, raised
    from program modules (such as trx_if.c or l1ctl.c).

  - l1ctl_link_fsm - L1CTL server state machine.

  - trx_interface_fsm - TRX interface state machine.

The program modules (such as trx_if.c or l1ctl.c) should be as
much independent from each other as possible. In other words,
one module should not call methods from another, e.g. L1CTL
handlers are not able to send any command to transceiver directly.

Instead of that, they should use shared event set to notify the
main state machine about something. Depending on current state
and received event, main state machine 'decides' what to do. This
approach would allow to easily reuse the source code almost 'as is'
anywhere outside the project.

Change-Id: I7ee6fc891abe5f775f5b7ebbf093181a97950dea

1 files changed, 101 insertions, 22 deletions

diff --git a/src/host/trxcon/trx_if.c b/src/host/trxcon/trx_if.c
index 5b0b7b1c..8f93b0a6 100644
--- a/src/host/trxcon/trx_if.c
+++ b/src/host/trxcon/trx_if.c
@@ -35,13 +35,49 @@
 #include <osmocom/core/socket.h>
 #include <osmocom/core/talloc.h>
 #include <osmocom/core/bits.h>
+#include <osmocom/core/fsm.h>
 
 #include <osmocom/gsm/gsm_utils.h>
 
+#include "trxcon.h"
 #include "trx_if.h"
 #include "logging.h"
 
 extern void *tall_trx_ctx;
+extern struct osmo_fsm_inst *trxcon_fsm;
+
+static struct osmo_fsm_state trx_fsm_states[] = {
+	[TRX_STATE_OFFLINE] = {
+		.out_state_mask = (
+			GEN_MASK(TRX_STATE_IDLE) |
+			GEN_MASK(TRX_STATE_RSP_WAIT)),
+		.name = "OFFLINE",
+	},
+	[TRX_STATE_IDLE] = {
+		.out_state_mask = UINT32_MAX,
+		.name = "IDLE",
+	},
+	[TRX_STATE_ACTIVE] = {
+		.out_state_mask = (
+			GEN_MASK(TRX_STATE_IDLE) |
+			GEN_MASK(TRX_STATE_RSP_WAIT)),
+		.name = "ACTIVE",
+	},
+	[TRX_STATE_RSP_WAIT] = {
+		.out_state_mask = (
+			GEN_MASK(TRX_STATE_IDLE) |
+			GEN_MASK(TRX_STATE_ACTIVE) |
+			GEN_MASK(TRX_STATE_OFFLINE)),
+		.name = "RSP_WAIT",
+	},
+};
+
+static struct osmo_fsm trx_fsm = {
+	.name = "trx_interface_fsm",
+	.states = trx_fsm_states,
+	.num_states = ARRAY_SIZE(trx_fsm_states),
+	.log_subsys = DTRX,
+};
 
 static int trx_udp_open(void *priv, struct osmo_fd *ofd, const char *host,
 	uint16_t port_local, uint16_t port_remote,
@@ -178,6 +214,12 @@ static void trx_ctrl_send(struct trx_instance *trx)
 	LOGP(DTRX, LOGL_DEBUG, "Sending control '%s'\n", tcm->cmd);
 	send(trx->trx_ofd_ctrl.fd, tcm->cmd, strlen(tcm->cmd) + 1, 0);
 
+	/* Trigger state machine */
+	if (trx->fsm->state != TRX_STATE_RSP_WAIT) {
+		trx->prev_state = trx->fsm->state;
+		osmo_fsm_inst_state_chg(trx->fsm, TRX_STATE_RSP_WAIT, 0, 0);
+	}
+
 	/* Start expire timer */
 	trx->trx_ctrl_timer.data = trx;
 	trx->trx_ctrl_timer.cb = trx_ctrl_timer_cb;
@@ -186,10 +228,25 @@ static void trx_ctrl_send(struct trx_instance *trx)
 
 static void trx_ctrl_timer_cb(void *data)
 {
+	struct trx_instance *trx = (struct trx_instance *) data;
+	struct trx_ctrl_msg *tcm;
+
+	/* Queue may be cleaned at this moment */
+	if (llist_empty(&trx->trx_ctrl_list))
+		return;
+
 	LOGP(DTRX, LOGL_NOTICE, "No response from transceiver...\n");
 
+	tcm = llist_entry(trx->trx_ctrl_list.next, struct trx_ctrl_msg, list);
+	if (++tcm->retry_cnt > 3) {
+		LOGP(DTRX, LOGL_NOTICE, "Transceiver offline\n");
+		osmo_fsm_inst_state_chg(trx->fsm, TRX_STATE_OFFLINE, 0, 0);
+		osmo_fsm_inst_dispatch(trxcon_fsm, TRX_EVENT_OFFLINE, trx);
+		return;
+	}
+
 	/* Attempt to send a command again */
-	trx_ctrl_send((struct trx_instance *) data);
+	trx_ctrl_send(trx);
 }
 
 /* Add a new CTRL command to the trx_ctrl_list */
@@ -200,11 +257,7 @@ static int trx_ctrl_cmd(struct trx_instance *trx, int critical,
 	int len, pending = 0;
 	va_list ap;
 
-	/*if (!transceiver_available && !!strcmp(cmd, "POWEROFF")) {
-		LOGP(DTRX, LOGL_ERROR, "CTRL ignored: No clock from "
-			"transceiver, please fix!\n");
-		return -EIO;
-	}*/
+	/* TODO: make sure that transceiver online */
 
 	if (!llist_empty(&trx->trx_ctrl_list))
 		pending = 1;
@@ -419,6 +472,18 @@ static int trx_ctrl_read_cb(struct osmo_fd *ofd, unsigned int what)
 			goto rsp_error;
 	}
 
+	/* Trigger state machine */
+	if (!strncmp(tcm->cmd + 4, "POWERON", 7))
+		osmo_fsm_inst_state_chg(trx->fsm, TRX_STATE_ACTIVE, 0, 0);
+	else if (!strncmp(tcm->cmd + 4, "POWEROFF", 8))
+		osmo_fsm_inst_state_chg(trx->fsm, TRX_STATE_IDLE, 0, 0);
+	else if (!strncmp(tcm->cmd + 4, "ECHO", 4)) {
+		osmo_fsm_inst_state_chg(trx->fsm, TRX_STATE_IDLE, 0, 0);
+		osmo_fsm_inst_dispatch(trxcon_fsm,
+			TRX_EVENT_RESET_IND, trx);
+	} else
+		osmo_fsm_inst_state_chg(trx->fsm, trx->prev_state, 0, 0);
+
 	/* Remove command from list */
 	llist_del(&tcm->list);
 	talloc_free(tcm);
@@ -429,10 +494,8 @@ static int trx_ctrl_read_cb(struct osmo_fd *ofd, unsigned int what)
 	return 0;
 
 rsp_error:
-	/**
-	 * TODO: stop/freeze trxcon process
-	 * or notify higher layers about the problem with L1
-	 */
+	/* Notify higher layers about the problem */
+	osmo_fsm_inst_dispatch(trxcon_fsm, TRX_EVENT_RSP_ERROR, trx);
 	return -EIO;
 }
 
@@ -512,6 +575,18 @@ int trx_if_data(struct trx_instance *trx, uint8_t tn, uint32_t fn,
 {
 	uint8_t buf[256];
 
+	/**
+	 * We must be sure that we have clock,
+	 * and we have sent all control data
+	 *
+	 * TODO: should we wait in TRX_STATE_RSP_WAIT state?
+	 */
+	if (trx->fsm->state != TRX_STATE_ACTIVE) {
+		LOGP(DTRX, LOGL_DEBUG, "Ignoring TX data, "
+			"transceiver isn't ready\n");
+		return -EAGAIN;
+	}
+
 	LOGP(DTRX, LOGL_DEBUG, "TX burst tn=%u fn=%u pwr=%u\n", tn, fn, pwr);
 
 	buf[0] = tn;
@@ -524,17 +599,8 @@ int trx_if_data(struct trx_instance *trx, uint8_t tn, uint32_t fn,
 	/* Copy ubits {0,1} */
 	memcpy(buf + 6, bits, 148);
 
-	/**
-	 * TODO: is transceiver available???
-	 *
-	 * We must be sure that we have clock,
-	 * and we have sent all control data
-	 *
-	 * if (transceiver_available && llist_empty(&l1h->trx_ctrl_list))
-	 *   send(l1h->trx_ofd_data.fd, buf, 154, 0);
-	 * else
-	 *   LOGP(DTRX, LOGL_DEBUG, "Ignoring TX data, transceiver offline.\n");
-	 */
+	/* Send data to transceiver */
+	send(trx->trx_ofd_data.fd, buf, 154, 0);
 
 	return 0;
 }
@@ -546,6 +612,7 @@ int trx_if_data(struct trx_instance *trx, uint8_t tn, uint32_t fn,
 int trx_if_open(struct trx_instance **trx, const char *host, uint16_t port)
 {
 	struct trx_instance *trx_new;
+	char *inst_name;
 	int rc;
 
 	LOGP(DTRX, LOGL_NOTICE, "Init transceiver interface\n");
@@ -576,6 +643,13 @@ int trx_if_open(struct trx_instance **trx, const char *host, uint16_t port)
 	if (rc < 0)
 		goto error;
 
+	/* Allocate a new dedicated state machine */
+	osmo_fsm_register(&trx_fsm);
+	inst_name = talloc_asprintf(trx_new, "%s:%u", host, port);
+	trx_new->fsm = osmo_fsm_inst_alloc(&trx_fsm, trx_new,
+		NULL, LOGL_DEBUG, inst_name);
+	talloc_free(inst_name);
+
 	*trx = trx_new;
 
 	return 0;
@@ -587,10 +661,14 @@ error:
 }
 
 /* Flush pending control messages */
-static void trx_if_flush_ctrl(struct trx_instance *trx)
+void trx_if_flush_ctrl(struct trx_instance *trx)
 {
 	struct trx_ctrl_msg *tcm;
 
+	/* Reset state machine */
+	osmo_fsm_inst_state_chg(trx->fsm, TRX_STATE_IDLE, 0, 0);
+
+	/* Clear command queue */
 	while (!llist_empty(&trx->trx_ctrl_list)) {
 		tcm = llist_entry(trx->trx_ctrl_list.next,
 			struct trx_ctrl_msg, list);
@@ -616,5 +694,6 @@ void trx_if_close(struct trx_instance *trx)
 	trx_udp_close(&trx->trx_ofd_data);
 
 	/* Free memory */
+	osmo_fsm_inst_free(trx->fsm);
 	talloc_free(trx);
 }