drivers: modem: nrf91-slm socket offloaded driver

This commit adds a socket offloaded driver for the Nordic
nRF91x Serial LTE Modem.

Signed-off-by: Wilkins White <ww@novadynamics.com>

Author: wilkinsw

drivers/modem/CMakeLists.txt

@@ -35,5 +35,7 @@ if (CONFIG_MODEM_SIM7080)
 	zephyr_library_sources(simcom-sim7080.c)
 endif()
 
+add_subdirectory_ifdef(CONFIG_MODEM_NRF91_SLM nordic)
+
 zephyr_library_sources_ifdef(CONFIG_MODEM_CELLULAR modem_cellular.c)
 zephyr_library_sources_ifdef(CONFIG_MODEM_AT_SHELL modem_at_shell.c)

drivers/modem/Kconfig

@@ -195,5 +195,6 @@ source "drivers/modem/Kconfig.at_shell"
 
 source "drivers/modem/Kconfig.hl7800"
 source "drivers/modem/Kconfig.simcom-sim7080"
+source "drivers/modem/nordic/Kconfig"
 
 endif # MODEM

drivers/modem/nordic/CMakeLists.txt

@@ -0,0 +1,4 @@
+# Copyright 2025 Nova Dynamics LLC
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library_sources(nrf91_slm_dns.c nrf91_slm_socket.c nrf91_slm.c)

drivers/modem/nordic/Kconfig

@@ -0,0 +1,33 @@
+# Copyright 2025 Nova Dynamics LLC
+# SPDX-License-Identifier: Apache-2.0
+
+config MODEM_NRF91_SLM
+	bool "Nordic nRF91x SLM Driver"
+	select MODEM_SOCKET
+	select NET_OFFLOAD
+	select NET_SOCKETS_OFFLOAD
+	select MODEM_MODULES
+	select MODEM_CHAT
+	select MODEM_PIPE
+	select MODEM_BACKEND_UART
+	select RING_BUFFER
+	depends on DT_HAS_NORDIC_NRF91_SLM_ENABLED
+	imply GPIO
+	help
+	  Enables the offloaded driver for the Nordic nRF91 Serial LTE Modem.
+
+if MODEM_NRF91_SLM
+
+config MODEM_NRF91_SLM_PERIODIC_SCRIPT_MS
+	int "Periodic script interval in milliseconds"
+	default 2000
+
+config MODEM_NRF91_SLM_UART_BUFFER_SIZES
+	int "The UART receive and transmit buffer sizes in bytes."
+	default 512
+
+config MODEM_NRF91_SLM_CHAT_BUFFER_SIZES
+	int "The size of the buffers used for the chat scripts in bytes."
+	default 128
+
+endif