drivers: add lpuarte driver and sample

Add low power uarte driver and sample.
Based on NCS LPUARTE driver and sample,
nrfconnect/sdk-nrf/commit/d33871cc92bc50034a6d9b7bdcac94c0ff358390

Signed-off-by: Eivind Jølsgard <[email protected]>

Author: eivindj-nordic

CODEOWNERS

@@ -34,6 +34,7 @@
 # Drivers
 /drivers/clock_control/                   @nrfconnect/ncs-bm
 /drivers/console/                         @nrfconnect/ncs-bm
+/drivers/lpuarte/                         @nrfconnect/ncs-bm
 
 # Include
 /include/*.h                              @nrfconnect/ncs-bm

boards/nordic/bm_nrf54l15dk/include/board-config.h

@@ -81,6 +81,30 @@ extern "C" {
 #define BOARD_APP_UARTE_PIN_CTS NRF_PIN_PORT_TO_PIN_NUMBER(3, 0)
 #endif
 
+/* Application UART configuration */
+#ifndef BOARD_APP_LPUARTE_INST
+#define BOARD_APP_LPUARTE_INST 21
+#endif
+
+#ifndef BOARD_APP_LPUARTE_PIN_TX
+#define BOARD_APP_LPUARTE_PIN_TX NRF_PIN_PORT_TO_PIN_NUMBER(11, 1)
+#endif
+#ifndef BOARD_APP_LPUARTE_PIN_RX
+#define BOARD_APP_LPUARTE_PIN_RX NRF_PIN_PORT_TO_PIN_NUMBER(10, 1)
+#endif
+#ifndef BOARD_APP_LPUARTE_PIN_RTS
+#define BOARD_APP_LPUARTE_PIN_RTS NRF_PIN_PORT_TO_PIN_NUMBER(14, 1)
+#endif
+#ifndef BOARD_APP_LPUARTE_PIN_CTS
+#define BOARD_APP_LPUARTE_PIN_CTS NRF_PIN_PORT_TO_PIN_NUMBER(13, 1)
+#endif
+#ifndef BOARD_APP_LPUARTE_PIN_REQ
+#define BOARD_APP_LPUARTE_PIN_REQ NRF_PIN_PORT_TO_PIN_NUMBER(8, 1)
+#endif
+#ifndef BOARD_APP_LPUARTE_PIN_RDY
+#define BOARD_APP_LPUARTE_PIN_RDY NRF_PIN_PORT_TO_PIN_NUMBER(9, 1)
+#endif
+
 #ifdef __cplusplus
 }
 #endif

drivers/CMakeLists.txt

@@ -10,3 +10,4 @@ add_compile_options($<TARGET_PROPERTY:compiler,warning_shadow_variables>)
 add_subdirectory_ifdef(CONFIG_CONSOLE console)
 add_subdirectory_ifdef(CONFIG_CLOCK_CONTROL clock_control)
 add_subdirectory_ifdef(CONFIG_FLASH flash)
+add_subdirectory_ifdef(CONFIG_BM_SW_LPUARTE lpuarte)

drivers/Kconfig

@@ -8,6 +8,7 @@ menu "Device Drivers"
 # zephyr-keep-sorted-start
 rsource "console/Kconfig"
 rsource "flash/Kconfig"
+rsource "lpuarte/Kconfig"
 # zephyr-keep-sorted-stop
 
 endmenu

drivers/lpuarte/CMakeLists.txt

@@ -0,0 +1,8 @@
+#
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+zephyr_library()
+
+zephyr_library_sources(lpuarte.c)

drivers/lpuarte/Kconfig

@@ -0,0 +1,60 @@
+# UART configuration
+
+# Copyright (c) 2025, Nordic Semiconductor ASA
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+
+config BM_SW_LPUARTE
+	bool "Low Power UARTE using REQ/RDY lines"
+	help
+	  Low power UARTE implements UARTE API and extends standard UARTE
+	  communication with 2 pins protocol for receiver wake up and flow control.
+
+if BM_SW_LPUARTE
+
+# Set number of event handlers used by the lpuart driver
+config NRFX_GPIOTE_NUM_OF_EVT_HANDLERS
+	default 2
+
+config BM_SW_LPUARTE_INIT_PRIORITY
+	int "Initialization priority"
+	default 45
+	help
+	  Initialization priority within POST_KERNEL level. It should be set to
+	  a value that ensures that device is initialized later than gpio and
+	  uart devices used by this device. Default is set to be between
+	  default (KERNEL_INIT_PRIORITY_DEFAULT) and device
+	  (KERNEL_INIT_PRIORITY_DEVICE).
+
+config BM_SW_LPUARTE_MAX_PACKET_SIZE
+	int "Maximum RX packet size"
+	default 128
+	help
+	  If interrupt driven API is enabled then internal RX buffer of that
+	  size is created.
+
+config BM_SW_LPUARTE_DEFAULT_TX_TIMEOUT
+	int "TX Timeout in microseconds"
+	default 1000000
+	help
+	  Timeout is used in uart_poll_out and uart_fifo_fill (if interrupt
+	  driven API is enabled).
+
+config BM_SW_LPUARTE_INT_DRIVEN
+	bool "Enable interrupt driven API"
+	help
+	  If enabled, then asynchronous API cannot be used
+
+config BM_SW_LPUARTE_INT_DRV_TX_BUF_SIZE
+	int "Tx buffer size"
+	default 128
+	depends on BM_SW_LPUARTE_INT_DRIVEN
+	help
+	  Internal buffer of that size is created and used by uart_fifo_fill.
+	  For optimal performance it should be able to fit the longest possible
+	  packet.
+
+module = BM_SW_LPUARTE
+module-str = low power uart
+source "subsys/logging/Kconfig.template.log_config"
+
+endif