boards: arm: Add Dragino NBSN95 NB-IoT node

add board support for Dragino NBSN95 NB-IoT sensor
node. Initial support only includes UART (with followup
patches on BC95 and other peripherals)

Signed-off-by: Parthiban Nallathambi <parthiban@linumiz.com>

boards/arm/dragino_nbsn95/Kconfig.board

@@ -0,0 +1,8 @@
+# Dragino NBSN95 NB-IoT Sensor Node board configuration
+
+# Copyright (c) 2021 Next Big Thing AG
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_DRAGINO_NBSN95
+	bool "Dragino NBSN95 Sensor Node"
+	depends on SOC_STM32L072XX

boards/arm/dragino_nbsn95/Kconfig.defconfig

@@ -0,0 +1,11 @@
+# Dragino NBSN95 NB-IoT Sensor Node board configuration
+
+# Copyright (c) 2021 Next Big Thing AG
+# SPDX-License-Identifier: Apache-2.0
+
+if BOARD_DRAGINO_NBSN95
+
+config BOARD
+	default "dragino_nbsn95"
+
+endif # BOARD_DRAGINO_NBSN95

boards/arm/dragino_nbsn95/board.cmake

@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: Apache-2.0
+
+board_runner_args(jlink "--device=STM32L072CZ" "--speed=4000")
+
+include(${ZEPHYR_BASE}/boards/common/openocd.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/jlink.board.cmake)

boards/arm/dragino_nbsn95/doc/index.rst

@@ -0,0 +1,195 @@
+.. _dragino_nbsn95_board:
+
+Dragino NBSN95 NB-IoT Sensor Node
+#################################
+
+Overview
+********
+
+The Dragino NBSN95 NB-IoT Sensor Node for IoT allows users to develop
+applications with NB-IoT connectivity via the Quectel BC95-G.
+Dragino NBSN95 enables a wide diversity of applications by exploiting
+low-power communication, ARM |reg| Cortex |reg|-M0 core-based
+STM32L0 Series features.
+
+This kit provides:
+
+- STM32L072CZ MCU
+- Quectel BC95-G NB-IoT
+- Expansion connectors:
+        - PMOD
+- Li/SOCI2 Unchargable Battery
+- GPIOs exposed via screw terminals on the carrier board
+- Housing
+
+.. image:: img/dragino_nbsn95.png
+     :width: 531px
+     :align: center
+     :height: 354px
+     :alt: Dragino NBSN95
+
+More information about the board can be found at the `Dragino NBSN95 website`_.
+
+Hardware
+********
+
+The STM32L072CZ SoC provides the following hardware IPs:
+
+- Ultra-low-power (down to 0.29 µA Standby mode and 93 uA/MHz run mode)
+- Core: ARM |reg| 32-bit Cortex |reg|-M0+ CPU, frequency up to 32 MHz
+- Clock Sources:
+
+        - 1 to 32 MHz crystal oscillator
+        - 32 kHz crystal oscillator for RTC (LSE)
+        - Internal 16 MHz factory-trimmed RC ( |plusminus| 1%)
+        - Internal low-power 37 kHz RC ( |plusminus| 5%)
+        - Internal multispeed low-power 65 kHz to 4.2 MHz RC
+- RTC with HW calendar, alarms and calibration
+- Up to 24 capacitive sensing channels: support touchkey, linear and rotary touch sensors
+- 11x timers:
+
+        - 2x 16-bit with up to 4 channels
+        - 2x 16-bit with up to 2 channels
+        - 1x 16-bit ultra-low-power timer
+        - 1x SysTick
+        - 1x RTC
+        - 2x 16-bit basic for DAC
+        - 2x watchdogs (independent/window)
+- Up to 84 fast I/Os, most 5 V-tolerant.
+- Memories
+
+        - Up to 192 KB Flash, 2 banks read-while-write, proprietary code readout protection
+        - Up to 20 KB of SRAM
+        - External memory interface for static memories supporting SRAM, PSRAM, NOR and NAND memories
+- Rich analog peripherals (independent supply)
+
+        - 1x 12-bit ADC 1.14 MSPS
+        - 2x 12-bit DAC
+        - 2x ultra-low-power comparators
+- 11x communication interfaces
+
+        - USB OTG 2.0 full-speed, LPM and BCD
+        - 3x I2C FM+(1 Mbit/s), SMBus/PMBus
+        - 4x USARTs (ISO 7816, LIN, IrDA, modem)
+        - 6x SPIs (4x SPIs with the Quad SPI)
+- 7-channel DMA controller
+- True random number generator
+- CRC calculation unit, 96-bit unique ID
+- Development support: serial wire debug (SWD), JTAG, Embedded Trace Macrocell |trade|
+
+
+More information about STM32L072CZ can be found here:
+
+        - `STM32L072CZ on www.st.com`_
+        - `STM32L0x2 reference manual`_
+
+Supported Features
+==================
+
+The Zephyr Dragino NBSN95 Board board configuration supports the following hardware features:
+
++-----------+------------+-------------------------------------+
+| Interface | Controller | Driver/Component                    |
++===========+============+=====================================+
+| UART      | on-chip    | serial port-polling;                |
+|           |            | serial port-interrupt               |
++-----------+------------+-------------------------------------+
+| PINMUX    | on-chip    | pinmux                              |
++-----------+------------+-------------------------------------+
+| GPIO      | on-chip    | gpio                                |
++-----------+------------+-------------------------------------+
+
+Other hardware features are not yet supported on this Zephyr port.
+
+The default configuration can be found in the defconfig file:
+
+	``boards/arm/dragino_nbsn95/dragino_nbsn95_defconfig``
+
+
+Connections and IOs
+===================
+
+Dragino NBSN95 Board has GPIO controllers. These controllers are responsible for pin muxing,
+input/output, pull-up, etc.
+
+Available pins:
+---------------
+
+For detailed information about available pins please refer to `Dragino NBSN95 website`_.
+
+Default Zephyr Peripheral Mapping:
+----------------------------------
+
+- UART_1_TX : PB6
+- UART_1_RX : PB7
+- UART_2_TX : PA2
+- UART_2_RX : PA3
+
+System Clock
+------------
+
+Dragino NBSN95 System Clock is at 32MHz,
+
+Serial Port
+-----------
+
+Dragino NBSN95 board has 2 U(S)ARTs. The Zephyr console output is assigned to UART1.
+Default settings are 115200 8N1.
+
+Programming and Debugging
+*************************
+
+Applications for the ``dragino_nbsn95`` board configuration can be built and
+flashed in the usual way (see :ref:`build_an_application` and
+:ref:`application_run` for more details).
+
+Flashing
+========
+
+Dragino NBSN95  board requires an external debugger.
+
+Flashing an application to Dragino NBSN95
+-----------------------------------------
+
+Here is an example for the :ref:`hello_world` application.
+
+Connect the Dragino NBSN95 to a STLinkV2 to your host computer using the USB port, then
+run a serial host program to connect with your board. For example:
+
+.. code-block:: console
+
+   $ minicom -D /dev/ttyACM0
+
+Then build and flash the application:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/hello_world
+   :board: dragino_nbsn95
+   :goals: build flash
+
+You should see the following message on the console:
+
+.. code-block:: console
+
+   $ Hello World! dragino_nbsn95
+
+Debugging
+=========
+
+You can debug an application in the usual way.  Here is an example for the
+:ref:`hello_world` application.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/hello_world
+   :board: dragino_nbsn95
+   :maybe-skip-config:
+   :goals: debug
+
+.. _Dragino NBSN95 website:
+   https://www.dragino.com/products/nb-iot/item/163-nbsn95.html
+
+.. _STM32L072CZ on www.st.com:
+   http://www.st.com/en/microcontrollers/stm32l072cz.html
+
+.. _STM32L0x2 reference manual:
+   http://www.st.com/resource/en/reference_manual/DM00108281.pdf

boards/arm/dragino_nbsn95/dragino_nbsn95.dts

@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2021 Next Big Thing AG
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+#include <st/l0/stm32l072Xz.dtsi>
+#include <st/l0/stm32l072c(b-z)tx-pinctrl.dtsi>
+
+/ {
+	model = "Dragino NBSN95 NB-IoT Sensor Node";
+	compatible = "vendor,dragino";
+
+	chosen {
+		zephyr,console = &usart2;
+		zephyr,shell-uart = &usart2;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+		green_led: led {
+			gpios = <&gpioa 8 GPIO_ACTIVE_HIGH>;
+			label = "User LD1";
+		};
+	};
+
+	aliases {
+		led0 = &green_led;
+	};
+};
+
+&clk_hsi {
+	status = "okay";
+};
+
+&pll {
+	div = <2>;
+	mul = <4>;
+	clocks = <&clk_hsi>;
+	status = "okay";
+};
+
+&rcc {
+	clocks = <&pll>;
+	clock-frequency = <DT_FREQ_M(32)>;
+	ahb-prescaler = <1>;
+	apb1-prescaler = <1>;
+	apb2-prescaler = <1>;
+};
+
+&usart1 {
+	pinctrl-0 = <&usart1_tx_pb6 &usart1_rx_pb7>;
+	current-speed = <115200>;
+	status = "okay";
+};
+
+&usart2 {
+	pinctrl-0 = <&usart2_tx_pa2 &usart2_rx_pa3>;
+	current-speed = <115200>;
+	status = "okay";
+};

boards/arm/dragino_nbsn95/dragino_nbsn95.yaml

@@ -0,0 +1,13 @@
+identifier: dragino_nbsn95
+name: Dragino NBSN95 NB-IoT Sensor Node
+type: mcu
+arch: arm
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools
+ram: 20
+flash: 192
+testing:
+  ignore_tags:
+    - net

boards/arm/dragino_nbsn95/dragino_nbsn95_defconfig

@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: Apache-2.0
+
+# Zephyr Kernel Configuration
+CONFIG_SOC_SERIES_STM32L0X=y
+
+# Platform Configuration
+CONFIG_SOC_STM32L072XX=y
+CONFIG_BOARD_DRAGINO_NBSN95=y
+
+# Serial Drivers
+CONFIG_SERIAL=y
+CONFIG_UART_INTERRUPT_DRIVEN=y
+# enable console
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y
+
+# Pinmux Driver
+CONFIG_PINMUX=y
+
+# GPIO Controller
+CONFIG_GPIO=y
+
+# Enable Clocks
+CONFIG_CLOCK_CONTROL=y

boards/arm/dragino_nbsn95/support/openocd.cfg

@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: Apache-2.0
+#
+# Copyright (c) 2021 Next Big Thing AG
+
+source [find interface/stlink.cfg]
+
+transport select hla_swd
+
+set WORKAREASIZE 0x2000
+
+source [find target/stm32l0_dual_bank.cfg]
+
+# There is only system reset line and JTAG/SWD command can be issued when SRST
+reset_config srst_only
+
+$_TARGETNAME configure -event gdb-attach {
+        echo "Debugger attaching: halting execution"
+        reset halt
+        gdb_breakpoint_override hard
+}
+
+$_TARGETNAME configure -event gdb-detach {
+        echo "Debugger detaching: resuming execution"
+        resume
+}