samples: subsys: lorawan: class_a: add clock sync option

Add an option to build the sample with application-layer clock sync
service running in the background.

This will also add a build-check for the clock sync service in CI.

Signed-off-by: Martin Jäger <martin@libre.solar>

samples/subsys/lorawan/class_a/README.rst

@@ -24,3 +24,19 @@ The following commands build and flash the sample.
    :board: nucleo_wl55jc
    :goals: build flash
    :compact:
+
+Extended Configuration
+**********************
+
+This sample can be configured to run the application-layer clock
+synchronization service in the background.
+
+The following commands build and flash the sample with clock synchronization
+enabled.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/subsys/lorawan/class_a
+   :board: nucleo_wl55jc
+   :goals: build flash
+   :gen-args: -DOVERLAY_CONFIG=overlay-clock-sync.conf
+   :compact:

samples/subsys/lorawan/class_a/overlay-clock-sync.conf

@@ -0,0 +1,3 @@
+CONFIG_LORAWAN_SERVICES=y
+CONFIG_LORAWAN_SERVICES_LOG_LEVEL_DBG=y
+CONFIG_LORAWAN_APP_CLOCK_SYNC=y

samples/subsys/lorawan/class_a/sample.yaml

@@ -44,3 +44,8 @@ tests:
     extra_configs:
       - CONFIG_LORAMAC_REGION_EU868=y
       - CONFIG_LORAMAC_REGION_US915=y
+  sample.lorawan.class_a.clock_sync:
+    extra_args: OVERLAY_CONFIG="overlay-clock-sync.conf"
+    filter: CONFIG_ENTROPY_HAS_DRIVER
+    integration_platforms:
+      - nucleo_wl55jc

samples/subsys/lorawan/class_a/src/main.c

@@ -98,6 +98,10 @@ void main(void)
 		return;
 	}
 
+#ifdef CONFIG_LORAWAN_APP_CLOCK_SYNC
+	lorawan_clock_sync_run();
+#endif
+
 	LOG_INF("Sending data...");
 	while (1) {
 		ret = lorawan_send(2, data, sizeof(data),