app: transport: Rewrite state handling

Rewrite of the state machine, which affects pretty much all code
in the module.
A few new states have been added, and all state transitions
will now happen from within the state handlers to avoid
races and ensure run-to-completion for all events.

Signed-off-by: Jan Tore Guggedal <[email protected]>

app/prj.conf

@@ -115,6 +115,8 @@ CONFIG_FPU=y
 CONFIG_ZBUS=y
 CONFIG_ZBUS_MSG_SUBSCRIBER=y
 CONFIG_ZBUS_MSG_SUBSCRIBER_NET_BUF_POOL_SIZE=32
+
+# Zephyr State Machine Framework
 CONFIG_SMF=y
 CONFIG_SMF_ANCESTOR_SUPPORT=y
 CONFIG_SMF_INITIAL_TRANSITION=y

app/src/common/message_channel.h

@@ -38,8 +38,9 @@ enum network_status {
 };
 
 enum cloud_status {
-	CLOUD_CONNECTED = 0x1,
-	CLOUD_DISCONNECTED,
+	CLOUD_DISCONNECTED = 0x1,
+	CLOUD_CONNECTED_READY_TO_SEND,
+	CLOUD_CONNECTED_PAUSED,
 };
 
 enum trigger_type {

app/src/common/modules_common.h

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+#ifndef _MODULES_COMMON_H_
+#define _MODULES_COMMON_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** @brief Set the initial state for a module.
+ *
+ *  @note The macro requires that a state machine object named s_obj is defined and that a
+ *	  state array named states is defined.
+ *
+ *  @param _state State to set as initial.
+ *
+ *  @return see smf_set_initial().
+ */
+#define STATE_SET_INITIAL(_state)	smf_set_initial(SMF_CTX(&s_obj), &states[_state])
+
+/** @brief Set the state for a module.
+ *
+ *  @note The macro requires that a state machine object named s_obj is defined and that a
+ *	  state array named states is defined.
+ *
+ *  @param _state State to set.
+ *
+ *  @return see smf_set_state().
+ */
+#define STATE_SET(_state)		smf_set_state(SMF_CTX(&s_obj), &states[_state])
+
+/** @brief Set the state for a module and handle the event.
+ *
+ *  @note The macro requires that a state machine object named s_obj is defined and that a
+ *	  state array named states is defined.
+ *
+ *  @param _state State to set.
+ *
+ *  @return see smf_set_handled().
+ */
+#define STATE_EVENT_HANDLED(_state)	smf_set_handled(SMF_CTX(&s_obj))
+
+/** @brief Run the state machine for a module.
+ *
+ *  @note The macro requires that a state machine object named s_obj is defined.
+ *
+ *  @return see smf_run_state().
+ */
+#define STATE_RUN()			smf_run_state(SMF_CTX(&s_obj))
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _MODULES_COMMON_H_ */

app/src/modules/app/app.c

@@ -161,7 +161,7 @@ static void app_task(void)
 				return;
 			}
 
-			if (cloud_status == CLOUD_CONNECTED) {
+			if (cloud_status == CLOUD_CONNECTED_READY_TO_SEND) {
 				LOG_DBG("Cloud connected");
 				LOG_DBG("Getting latest device configuration from device shadow");
 

app/src/modules/fota/fota.c

@@ -47,7 +47,7 @@ void fota_callback(const struct zbus_channel *chan)
 	{
 		const enum cloud_status *status = zbus_chan_const_msg(chan);
 
-		if (*status == CLOUD_CONNECTED)
+		if (*status == CLOUD_CONNECTED_READY_TO_SEND)
 		{
 			LOG_DBG("Cloud connected, initializing FOTA");
 			err = nrf_cloud_fota_poll_init(&ctx);