lora: LoRa Basics Modem backend for SX12xx chips

As a first integration of the LoRa Basics Modem backend, implement the
LoRa API for the standard SX126x/SX127x chips.

Much of the logic from `lbm_common.c` is taken from the loramac-node
`sx12xx_common` implementation, but it should now be agnostic for all
LoRa RF transceivers.

Signed-off-by: Jordan Yates <jordan@embeint.com>

Author: JordanYates

drivers/lora/CMakeLists.txt

@@ -3,3 +3,4 @@
 zephyr_sources_ifdef(CONFIG_LORA_SHELL shell.c)
 
 add_subdirectory_ifdef(CONFIG_LORA_MODULE_BACKEND_LORAMAC_NODE loramac_node)
+add_subdirectory_ifdef(CONFIG_LORA_MODULE_BACKEND_LORA_BASICS_MODEM lora_basics_modem)

drivers/lora/Kconfig

@@ -22,6 +22,14 @@ config LORA_MODULE_BACKEND_LORAMAC_NODE
 	bool "loramac-node backend"
 	depends on ZEPHYR_LORAMAC_NODE_MODULE
 
+config LORA_MODULE_BACKEND_LORA_BASICS_MODEM
+	bool "LoRa Basic modem backend [EXPERIMENTAL]"
+	depends on ZEPHYR_LORA_BASICS_MODEM_MODULE
+	depends on DT_HAS_SEMTECH_SX1262_ENABLED || DT_HAS_SEMTECH_SX1261_ENABLED || DT_HAS_SEMTECH_SX1272_ENABLED || DT_HAS_SEMTECH_SX1276_ENABLED
+	select USE_LORA_BASICS_MODEM_DRIVERS
+	help
+	  Experimental support for implementing the LoRa API using the LoRa Basics Modem module.
+
 endchoice
 
 module = LORA
@@ -42,5 +50,6 @@ config LORA_INIT_PRIORITY
 
 rsource "Kconfig.sx12xx"
 rsource "Kconfig.rylrxxx"
+rsource "lora_basics_modem/Kconfig"
 
 endif # LORA

drivers/lora/lora_basics_modem/CMakeLists.txt

@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: Apache-2.0
+
+# LoRa drivers depend on the include directories exposed by the lora_basics_modem
+# library. Hence, if it exists then the source files are added to that otherwise
+# a library with same name is created.
+if(TARGET lora_basics_modem)
+  set(ZEPHYR_CURRENT_LIBRARY lora_basics_modem)
+else()
+  zephyr_library_named(lora_basics_modem)
+endif()
+
+zephyr_library_sources(lbm_common.c)
+zephyr_library_sources_ifdef(CONFIG_LORA_SX126X lbm_sx126x.c)
+zephyr_library_sources_ifdef(CONFIG_LORA_SX127X lbm_sx127x.c)
+zephyr_library_sources_ifdef(CONFIG_LORA_RYLRXXX ../rylrxxx.c)

drivers/lora/lora_basics_modem/Kconfig

@@ -0,0 +1,16 @@
+#
+# Copyright (c) 2025 Embeint Inc
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+if LORA_MODULE_BACKEND_LORA_BASICS_MODEM
+
+config LORA_BASICS_MODEM_ASYNC_RX_MAX_PAYLOAD
+	int "Maximum size payload that can be received by async RX"
+	default 256
+	help
+		A buffer of this size is allocated on the system workqueue stack when
+		running the async RX handler.
+
+endif