lib: nrf_modem_lib: Add connection manager backend for NTN

lib/nrf_modem_lib/Kconfig.modemlib

@@ -272,6 +272,7 @@ config NRF_MODEM_LIB_FAULT_STRERROR
 	  The description can be retrieved with nrf_modem_lib_fault_strerror().
 
 rsource "lte_net_if/Kconfig"
+rsource "lte_net_if/Kconfig.ntn"
 rsource "shell/Kconfig"
 
 DT_IPC := $(dt_nodelabel_path,ipc)

lib/nrf_modem_lib/lte_net_if/CMakeLists.txt

@@ -6,3 +6,6 @@
 
 target_sources(app PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/lte_net_if.c)
 target_sources(app PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/lte_ip_addr_helper.c)
+
+# Add NTN source file when NTN is enabled
+target_sources_ifdef(CONFIG_NRF_MODEM_LIB_NET_IF_NTN app PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/lte_net_if_ntn.c)

lib/nrf_modem_lib/lte_net_if/Kconfig.ntn

@@ -0,0 +1,77 @@
+#
+# Copyright (c) 2023 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+menuconfig NRF_MODEM_LIB_NET_IF_NTN
+	bool "nRF91 LTE network interface for NTN (Non-Terrestrial Network)"
+	depends on NRF_MODEM_LIB
+	select CONN_MGR_CONNECTIVITY
+	help
+	  Enable nRF91 LTE network interface for NTN (Non-Terrestrial Network).
+	  This provides a separate network interface specifically for NTN connectivity,
+	  allowing applications to choose between terrestrial and non-terrestrial networks.
+
+	  This works alongside the regular LTE network interface and provides similar
+	  functionality but optimized for satellite communication.
+
+if NRF_MODEM_LIB_NET_IF_NTN
+
+config NRF_MODEM_LIB_NET_IF_NTN_AUTO_START
+	bool "Auto-start NTN interface"
+	help
+	  Automatically start the NTN network interface when the system starts.
+	  When enabled, the NTN interface will be brought up automatically during
+	  system initialization.
+
+config NRF_MODEM_LIB_NET_IF_NTN_CONNECT_TIMEOUT_SECONDS
+	int "NTN LTE connection timeout in seconds"
+	range 0 86400
+	default 120
+	help
+	  Time period (in seconds) that the connectivity layer will attempt to establish
+	  an NTN LTE connection for, before timing out. If set to 0, no timeout is applied.
+
+	  NTN connections may take longer to establish than terrestrial connections
+	  due to the nature of satellite communication, so a longer timeout is recommended.
+
+config NRF_MODEM_LIB_NET_IF_NTN_CONNECTION_PERSISTENCE
+	bool "NTN Connection persistence"
+	default y
+	help
+	  When enabled, the NTN connectivity layer will attempt to keep the NTN LTE connection
+	  active, even after a connection loss, by automatically re-establishing the connection.
+
+	  This is particularly useful for NTN connections where connectivity may be
+	  intermittent due to satellite coverage patterns.
+
+config NRF_MODEM_LIB_NET_IF_NTN_AUTO_CONNECT
+	bool "Auto-connect for NTN interface"
+	default y
+	help
+	  Automatically connect the NTN interface when it is brought up.
+	  If disabled, the application will need to manually trigger NTN connections.
+
+config NRF_MODEM_LIB_NET_IF_NTN_AUTO_DOWN
+	bool "Auto-down for NTN interface"
+	default y
+	help
+	  Automatically bring down the NTN interface when network connectivity is lost.
+	  If disabled, the interface will remain up even without network connectivity.
+
+config NRF_MODEM_LIB_NET_IF_NTN_DOWN_DEFAULT_LTE_DISCONNECT
+	bool "Disconnect NTN LTE on interface down"
+	default y
+	help
+	  When the NTN network interface is brought down, disconnect from NTN LTE instead
+	  of shutting down the modem completely. This allows for faster re-connection
+	  and preserves the ability to use other network interfaces.
+
+module = NRF_MODEM_LIB_NET_IF_NTN
+module-dep = LOG
+module-str = nRF91 NTN LTE network interface
+module-help = Enables logging for nRF91 NTN LTE network interface.
+source "subsys/logging/Kconfig.template.log_config"
+
+endif # NRF_MODEM_LIB_NET_IF_NTN

lib/nrf_modem_lib/lte_net_if/lte_net_if_ntn.c

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2023 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ *
+ */
+
+#include <zephyr/device.h>
+#include <zephyr/types.h>
+#include <zephyr/net/offloaded_netdev.h>
+#include <zephyr/net/conn_mgr_connectivity_impl.h>
+#include <zephyr/logging/log.h>
+#include <modem/nrf_modem_lib.h>
+#include <modem/lte_lc.h>
+#include <modem/pdn.h>
+
+#include "lte_ip_addr_helper.h"
+
+LOG_MODULE_REGISTER(nrf_modem_lib_netif_ntn, CONFIG_NRF_MODEM_LIB_NET_IF_NTN_LOG_LEVEL);
+
+/* Forward declarations */
+static int lte_net_if_disconnect_ntn(struct conn_mgr_conn_binding *const if_conn);
+
+static void lte_net_if_init_ntn(struct conn_mgr_conn_binding *if_conn)
+{
+	LOG_DBG("Initializing NTN modem network interface");
+
+        /* Init stuff goes here */
+}
+
+int lte_net_if_enable_ntn(void)
+{
+        LOG_DBG("Enabling NTN");
+
+	if (!nrf_modem_is_initialized()) {
+		return nrf_modem_lib_init();
+	}
+
+	return 0;
+}
+
+int lte_net_if_disable_ntn(void)
+{
+        LOG_DBG("Disabling NTN");
+
+	if (IS_ENABLED(CONFIG_NRF_MODEM_LIB_NET_IF_NTN_DOWN_DEFAULT_LTE_DISCONNECT)) {
+		return lte_net_if_disconnect_ntn(NULL);
+	} else {
+		return nrf_modem_lib_shutdown();
+	}
+
+        return 0;
+}
+
+static int lte_net_if_connect_ntn(struct conn_mgr_conn_binding *const if_conn)
+{
+	ARG_UNUSED(if_conn);
+
+        LOG_DBG("Connecting to NTN");
+
+        /* Connect stuff goes here */
+
+	return 0;
+}
+
+static int lte_net_if_disconnect_ntn(struct conn_mgr_conn_binding *const if_conn)
+{
+	ARG_UNUSED(if_conn);
+
+        LOG_DBG("Disconnecting from NTN");
+
+        /* Disconnect stuff goes here */
+
+	return 0;
+}
+
+/* Bind connectivity APIs for NTN.
+ * extern in nrf9x_sockets.c
+ */
+struct conn_mgr_conn_api lte_net_if_conn_mgr_api_ntn = {
+	.init = lte_net_if_init_ntn,
+	.connect = lte_net_if_connect_ntn,
+	.disconnect = lte_net_if_disconnect_ntn,
+};

lib/nrf_modem_lib/nrf9x_sockets.c

@@ -42,6 +42,7 @@
  * Required but not implemented.
  */
 #define NRF_MODEM_LIB_NET_IF_CTX_TYPE void *
+#define NRF_MODEM_LIB_NET_IF_NTN_CTX_TYPE void *
 
 #define OBJ_TO_SD(obj) (((struct nrf_sock_ctx *)obj)->nrf_fd)
 #define OBJ_TO_CTX(obj) ((struct nrf_sock_ctx *)obj)
@@ -1177,10 +1178,58 @@ NET_DEVICE_OFFLOAD_INIT(nrf9x_socket, "nrf9x_socket",
 			&nrf9x_iface_data, NULL,
 			0, &nrf9x_iface_offload_api, 1280);
 
+#if defined(CONFIG_NRF_MODEM_LIB_NET_IF_NTN)
+static struct nrf9x_iface_data_ntn {
+	struct net_if *iface;
+} nrf9x_iface_data_ntn;
+
+static void nrf9x_iface_api_init_ntn(struct net_if *iface)
+{
+	nrf9x_iface_data_ntn.iface = iface;
+
+	iface->if_dev->socket_offload = nrf9x_socket_create;
+
+	/* NTN shares the same DNS offload operations */
+	socket_offload_dns_register(&nrf9x_socket_dns_offload_ops);
+
+	if (!IS_ENABLED(CONFIG_NRF_MODEM_LIB_NET_IF_NTN_AUTO_START)) {
+		net_if_flag_set(iface, NET_IF_NO_AUTO_START);
+	}
+}
+
+static int nrf9x_iface_enable_ntn(const struct net_if *iface, bool enabled)
+{
+	/* Enables or disable the NTN device (in response to admin state change) */
+	extern int lte_net_if_enable_ntn(void);
+	extern int lte_net_if_disable_ntn(void);
+
+	return enabled ? lte_net_if_enable_ntn() :
+			 lte_net_if_disable_ntn();
+}
+
+static struct offloaded_if_api nrf9x_iface_offload_api_ntn = {
+	.iface_api.init = nrf9x_iface_api_init_ntn,
+	.enable = nrf9x_iface_enable_ntn,
+};
+
+/* NTN network device for Non-Terrestrial Network */
+NET_DEVICE_OFFLOAD_INIT(nrf9x_socket_ntn, "nrf9x_socket_ntn",
+			nrf9x_socket_offload_init,
+			NULL,
+			&nrf9x_iface_data_ntn, NULL,
+			0, &nrf9x_iface_offload_api_ntn, 1280);
+#endif /* CONFIG_NRF_MODEM_LIB_NET_IF_NTN */
+
 #if defined(CONFIG_NRF_MODEM_LIB_NET_IF)
 extern struct conn_mgr_conn_api lte_net_if_conn_mgr_api;
 CONN_MGR_CONN_DEFINE(NRF_MODEM_LIB_NET_IF, &lte_net_if_conn_mgr_api);
 CONN_MGR_BIND_CONN(nrf9x_socket, NRF_MODEM_LIB_NET_IF);
 #endif /* CONFIG_NRF_MODEM_LIB_NET_IF */
 
+#if defined(CONFIG_NRF_MODEM_LIB_NET_IF_NTN)
+extern struct conn_mgr_conn_api lte_net_if_conn_mgr_api_ntn;
+CONN_MGR_CONN_DEFINE(NRF_MODEM_LIB_NET_IF_NTN, &lte_net_if_conn_mgr_api_ntn);
+CONN_MGR_BIND_CONN(nrf9x_socket_ntn, NRF_MODEM_LIB_NET_IF_NTN);
+#endif /* CONFIG_NRF_MODEM_LIB_NET_IF_NTN */
+
 #endif /* CONFIG_NET_SOCKETS_OFFLOAD */

samples/net/ntn/CMakeLists.txt

@@ -0,0 +1,16 @@
+#
+# Copyright (c) 2023 Nordic Semiconductor
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+cmake_minimum_required(VERSION 3.20.0)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(ntn)
+
+# NORDIC SDK APP START
+target_sources(app PRIVATE src/main.c)
+# NORDIC SDK APP END
+
+zephyr_include_directories(src)

samples/net/ntn/Kconfig

@@ -0,0 +1,33 @@
+#
+# Copyright (c) 2023 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+menu "NTN sample settings"
+
+config NTN_SAMPLE_DATA_UPLOAD_SIZE_BYTES
+	int "Number of bytes transmitted to the server"
+	default 10
+
+config NTN_SAMPLE_DATA_UPLOAD_FREQUENCY_SECONDS
+	int "How often data is transmitted to the server"
+	default 900
+
+config NTN_SAMPLE_SERVER_ADDRESS_STATIC
+	string "UDP server IP address"
+	default "8.8.8.8"
+
+config NTN_SAMPLE_SERVER_PORT
+	int "UDP server port number"
+	default "2469"
+
+endmenu
+
+module = NTN_SAMPLE
+module-str = NTN sample
+source "$(ZEPHYR_BASE)/subsys/logging/Kconfig.template.log_config"
+
+menu "Zephyr Kernel"
+source "Kconfig.zephyr"
+endmenu

samples/net/ntn/boards/nrf9151dk_nrf9151_ns.conf

@@ -0,0 +1,40 @@
+#
+# Copyright (c) 2024 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+# Modem trace
+CONFIG_NRF_MODEM_LIB_TRACE=y
+CONFIG_NRF_MODEM_LIB_TRACE_BACKEND_UART=y
+CONFIG_SERIAL=y
+CONFIG_UART_ASYNC_API=y
+CONFIG_UART_1_ASYNC=y
+CONFIG_UART_1_INTERRUPT_DRIVEN=n
+
+# Disable Duplicate Address Detection (DAD)
+# due to not being properly implemented for offloaded interfaces.
+CONFIG_NET_IPV6_NBR_CACHE=n
+CONFIG_NET_IPV6_MLD=n
+
+# Offload  network operations to the modem.
+CONFIG_NET_SOCKETS_OFFLOAD=y
+
+# Zephyr NET Connection Manager and Connectivity layer.
+CONFIG_NET_CONNECTION_MANAGER_MONITOR_STACK_SIZE=1024
+CONFIG_NRF_MODEM_LIB_NET_IF=y
+CONFIG_NRF_MODEM_LIB_NET_IF_LOG_LEVEL_DBG=y
+CONFIG_NRF_MODEM_LIB_NET_IF_NTN=y
+CONFIG_NRF_MODEM_LIB_NET_IF_NTN_LOG_LEVEL_DBG=y
+
+## PSM
+CONFIG_LTE_PSM_REQ=y
+CONFIG_LTE_PSM_REQ_RPTAU="00100001"
+CONFIG_LTE_PSM_REQ_RAT="00000000"
+
+## eDRX
+CONFIG_LTE_EDRX_REQ=n
+CONFIG_LTE_EDRX_REQ_VALUE_LTE_M="1001"
+
+## RAI
+CONFIG_LTE_RAI_REQ=n

samples/net/ntn/boards/nrf9151dk_nrf9151_ns.overlay

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+/* Enable uart1 for tracing. */
+&uart1 {
+	status = "okay";
+	current-speed = < 1000000 >;
+	hw-flow-control;
+};
+
+/ {
+	chosen {
+		nordic,modem-trace-uart = &uart1;
+	};
+};

samples/net/ntn/prj.conf

@@ -0,0 +1,21 @@
+#
+# Copyright (c) 2023 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+# General configurations
+CONFIG_LOG=y
+
+# Network
+CONFIG_NETWORKING=y
+CONFIG_NET_NATIVE=y
+CONFIG_NET_IPV4=y
+CONFIG_NET_SOCKETS=y
+CONFIG_POSIX_API=y
+CONFIG_NET_CONNECTION_MANAGER=y
+
+# Heap and stacks
+CONFIG_HEAP_MEM_POOL_SIZE=1280
+CONFIG_MAIN_STACK_SIZE=4096
+CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048