From 6fbbd6de24a8958745668343a8f13c6fa3c60668 Mon Sep 17 00:00:00 2001
From: Luis Ubieda <luisf@croxel.com>
Date: Wed, 6 Mar 2024 13:17:38 -0500
Subject: [PATCH] bluetooth: nus: Add Kconfig option to auto-start Bluetooth LE

Enables compatibility of NUS for codebases that are not
Bluetooth-centric (e.g: Non-bluetooth samples that use UART over
Bluetooth LE for Console, Logging, Shell, others).

Signed-off-by: Luis Ubieda <luisf@croxel.com>
---
 subsys/bluetooth/services/nus/CMakeLists.txt  |  4 +++
 subsys/bluetooth/services/nus/Kconfig.nus     |  7 ++++
 .../services/nus/bt_nus_auto_start_bt.c       | 36 +++++++++++++++++++
 3 files changed, 47 insertions(+)
 create mode 100644 subsys/bluetooth/services/nus/bt_nus_auto_start_bt.c

diff --git a/subsys/bluetooth/services/nus/CMakeLists.txt b/subsys/bluetooth/services/nus/CMakeLists.txt
index 31ecfa68b1..a15271cba3 100644
--- a/subsys/bluetooth/services/nus/CMakeLists.txt
+++ b/subsys/bluetooth/services/nus/CMakeLists.txt
@@ -8,3 +8,7 @@ zephyr_library_sources(
 	nus.c
 	nus_inst.c
 )
+
+zephyr_library_sources_ifdef(CONFIG_BT_NUS_AUTO_START_BLUETOOTH
+	bt_nus_auto_start_bt.c
+)
diff --git a/subsys/bluetooth/services/nus/Kconfig.nus b/subsys/bluetooth/services/nus/Kconfig.nus
index b74a359980..1841226d7c 100644
--- a/subsys/bluetooth/services/nus/Kconfig.nus
+++ b/subsys/bluetooth/services/nus/Kconfig.nus
@@ -16,4 +16,11 @@ config BT_NUS_DEFAULT_INSTANCE
 	  BT_NUS_INST_DEFINE(), it may not be beneficial having an internal
 	  instance as well.
 
+config BT_NUS_AUTO_START_BLUETOOTH
+	bool "Auto-enable Bluetooth stack and start LE advertisements"
+	help
+	  Auto-Enable the Bluetooth stack and start advertising with the NUS
+	  UUID. Useful to run applications that inherently do not deal with
+	  Bluetooth (e.g: Non-Bluetooth samples using UART over Bluetooth LE).
+
 endif # BT_NUS
diff --git a/subsys/bluetooth/services/nus/bt_nus_auto_start_bt.c b/subsys/bluetooth/services/nus/bt_nus_auto_start_bt.c
new file mode 100644
index 0000000000..be7b16998a
--- /dev/null
+++ b/subsys/bluetooth/services/nus/bt_nus_auto_start_bt.c
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2024 Croxel, Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/kernel.h>
+#include <zephyr/bluetooth/bluetooth.h>
+#include <zephyr/bluetooth/services/nus.h>
+
+#define DEVICE_NAME		CONFIG_BT_DEVICE_NAME
+#define DEVICE_NAME_LEN		(sizeof(DEVICE_NAME) - 1)
+
+static const struct bt_data ad[] = {
+	BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
+	BT_DATA(BT_DATA_NAME_COMPLETE, DEVICE_NAME, DEVICE_NAME_LEN),
+};
+
+static const struct bt_data sd[] = {
+	BT_DATA_BYTES(BT_DATA_UUID128_ALL, BT_UUID_NUS_SRV_VAL),
+};
+
+static int bt_nus_auto_start(void)
+{
+	int err;
+
+	err = bt_enable(NULL);
+	__ASSERT_NO_MSG(!err);
+
+	err = bt_le_adv_start(BT_LE_ADV_CONN, ad, ARRAY_SIZE(ad), sd, ARRAY_SIZE(sd));
+	__ASSERT_NO_MSG(!err);
+
+	return 0;
+}
+
+SYS_INIT(bt_nus_auto_start, APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY);