feat(ble): Add event `zmk_ble_advertising_status_changed`

Add event `zmk_ble_advertising_status_changed` to notify about
advertising status changes.
New advertising status will be send within the event data.

Closes: #2872

app/CMakeLists.txt

@@ -81,6 +81,7 @@ if ((NOT CONFIG_ZMK_SPLIT) OR CONFIG_ZMK_SPLIT_ROLE_CENTRAL)
 
   if (CONFIG_ZMK_BLE)
     target_sources(app PRIVATE src/events/ble_active_profile_changed.c)
+    target_sources(app PRIVATE src/events/ble_advertising_status_changed.c)
     target_sources(app PRIVATE src/behaviors/behavior_bt.c)
     target_sources(app PRIVATE src/ble.c)
     target_sources(app PRIVATE src/hog.c)

app/include/zmk/ble.h

@@ -19,6 +19,12 @@
 #define ZMK_BLE_PROFILE_COUNT CONFIG_BT_MAX_PAIRED
 #endif
 
+enum zmk_ble_advertising_type {
+    ZMK_ADV_NONE,
+    ZMK_ADV_DIR,
+    ZMK_ADV_CONN,
+};
+
 void zmk_ble_clear_bonds(void);
 int zmk_ble_prof_next(void);
 int zmk_ble_prof_prev(void);

app/include/zmk/events/ble_advertising_status_changed.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <zephyr/kernel.h>
+#include <zmk/event_manager.h>
+#include <zephyr/device.h>
+
+#include <zmk/ble.h>
+
+struct zmk_ble_advertising_status_changed {
+    enum zmk_ble_advertising_type advertising_status;
+};
+
+ZMK_EVENT_DECLARE(zmk_ble_advertising_status_changed);

app/src/ble.c

@@ -36,6 +36,7 @@ LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
 #include <zmk/split/bluetooth/uuid.h>
 #include <zmk/event_manager.h>
 #include <zmk/events/ble_active_profile_changed.h>
+#include <zmk/events/ble_advertising_status_changed.h>
 
 #if IS_ENABLED(CONFIG_ZMK_BLE_PASSKEY_ENTRY)
 #include <zmk/events/keycode_state_changed.h>
@@ -47,11 +48,7 @@ RING_BUF_DECLARE(passkey_entries, PASSKEY_DIGITS);
 
 #endif /* IS_ENABLED(CONFIG_ZMK_BLE_PASSKEY_ENTRY) */
 
-enum advertising_type {
-    ZMK_ADV_NONE,
-    ZMK_ADV_DIR,
-    ZMK_ADV_CONN,
-} advertising_status;
+enum zmk_ble_advertising_type advertising_status;
 
 #define CURR_ADV(adv) (adv << 4)
 
@@ -179,7 +176,8 @@ int update_advertising(void) {
     int err = 0;
     bt_addr_le_t *addr;
     struct bt_conn *conn;
-    enum advertising_type desired_adv = ZMK_ADV_NONE;
+    enum zmk_ble_advertising_type desired_adv = ZMK_ADV_NONE;
+    enum zmk_ble_advertising_type previous_adv = advertising_status;
 
     if (zmk_ble_active_profile_is_open()) {
         desired_adv = ZMK_ADV_CONN;
@@ -217,6 +215,11 @@ int update_advertising(void) {
         break;
     }
 
+    if (previous_adv != advertising_status) {
+        raise_zmk_ble_advertising_status_changed(
+            (struct zmk_ble_advertising_status_changed){.advertising_status = advertising_status});
+    }
+
     return 0;
 };
 

app/src/events/ble_advertising_status_changed.c

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2025 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <zephyr/kernel.h>
+#include <zmk/events/ble_advertising_status_changed.h>
+
+ZMK_EVENT_IMPL(zmk_ble_advertising_status_changed);