boards: arm: add support for STM32G071B Discovery board

Support the ST STM32G071B Discovery board with STM32G071RBTX SoC

Tested with:
    - `samples/basic/blinky`
    - `samples/basic/button`

Flashed samples via On-Board ST-LINK with:
    - west flash

Signed-off-by: Sam Hurst <sbh1187@gmail.com>

boards/arm/stm32g071b_disco/Kconfig.board

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+# STM32G071B Discovery board configuration
+
+# Copyright 2021 The Chromium OS Authors
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_STM32G071B_DISCO
+	bool "STM32G071B Discovery Board"
+	depends on SOC_STM32G071XX

boards/arm/stm32g071b_disco/Kconfig.defconfig

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+# STM32G071B Discovery board configuration
+
+# Copyright 2021 The Chromium OS Authors
+# SPDX-License-Identifier: Apache-2.0
+
+if BOARD_STM32G071B_DISCO
+
+config BOARD
+	default "stm32g071b_disco"
+
+endif # BOARD_STM32G071B_DISCO

boards/arm/stm32g071b_disco/board.cmake

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+# SPDX-License-Identifier: Apache-2.0
+
+board_runner_args(stm32cubeprogrammer "--port=swd" "--reset=hw")
+
+include(${ZEPHYR_BASE}/boards/common/stm32cubeprogrammer.board.cmake)
+

boards/arm/stm32g071b_disco/doc/index.rst

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+.. _stm32g071b_disco_board:
+
+ST STM32G071B Discovery
+#######################
+
+Overview
+********
+The STM32G071B-DISCO Discovery board is a demonstration and development platform
+for the STMicroelectronics Arm® Cortex® -M0+ core-based STM32G071RB USB Type-C™
+and Power Delivery microcontroller. The STM32G071B-DISCO Discovery board is
+presented with all necessary interfaces for easy connection and
+interoperability with other USB Type-C™ devices. The STM32G071B-DISCO Discovery
+board is intended for discovery and display of USB Type-C™ port characteristics
+such as data role, power role, VBUS and IBUS monitoring. It offers an advanced
+user mode when associated with the STM32CubeMonUCPD software GUI and can be used
+as a USB Type-C™ and Power Delivery analyzer.
+
+- STM32G071RBT6 microcontroller featuring 128 Kbytes of Flash memory and
+  32 Kbytes of RAM in LQFP64 package
+- Plastic case
+- 1” 128 x 64 pixels OLED LCD module with SPI interface
+- USB Type-C™ interface plug cable and receptacle connector accessible by door
+  with reed sensor detection
+- 3 bidirectional current and power monitors with I2C interface to measure VBUS,
+  CC1 and CC2 protected and isolated lines
+- On-board DC/DC converter to sustain power supply with VBUS varying from 3 V to
+  20 V (+/- 5 %)
+- 4 user status LEDs about USB Type-C™ configuration
+- 3 LEDs for power and ST-LINK communication
+- 4-way joystick with selection button
+- 1 reset push-button
+- Board external connectors:
+    - USB Type-C™ plug cable
+    - USB Type-C™ receptacle connector
+    - 8-pin user extension connector including ADC, SPI, USART and
+      I2C communication signals
+    - USB with Micro-AB (ST-LINK)
+- Board internal connectors:
+    - 2 x 8-pin GPIOs free pins from microcontroller
+	  (accessible internally when case is removed)
+    - USB Type-C™ test points for main signals
+- Flexible power-supply options: ST-LINK USB VBUS or USB Type-C™ VBUS
+- On-board ST-LINK/V2-1 debugger/programmer with USB enumeration capability:
+  mass storage, Virtual COM port and debug port
+
+.. image:: img/stm32g071b_disco.jpg
+   :width: 500px
+   :height: 450px
+   :align: center
+   :alt: STM32G071B-DISCO
+
+More information about the board can be found at the `STM32G071B-DISCO website`_.
+
+
+More information about STM32G071RB can be found here:
+- `G071RB on www.st.com`_
+- `STM32G071 reference manual`_
+
+
+Supported Features
+==================
+
+The Zephyr stm32g071b_disco board configuration supports the following hardware features:
+
++-----------+------------+-------------------------------------+
+| Interface | Controller | Driver/Component                    |
++===========+============+=====================================+
+| NVIC      | on-chip    | nested vector interrupt controller  |
++-----------+------------+-------------------------------------+
+| UART      | on-chip    | serial port-polling;                |
+|           |            | serial port-interrupt               |
++-----------+------------+-------------------------------------+
+| GPIO      | on-chip    | gpio                                |
++-----------+------------+-------------------------------------+
+| WATCHDOG  | on-chip    | independent watchdog                |
++-----------+------------+-------------------------------------+
+
+Other hardware features are not yet supported in this Zephyr port.
+
+The default configuration can be found in the defconfig file:
+``boards/arm/stm32g071b_disco/stm32g071b_disco_defconfig``
+
+Connections and IOs
+===================
+
+Each of the GPIO pins can be configured by software as output (push-pull or open-drain), as
+input (with or without pull-up or pull-down), or as peripheral alternate function. Most of the
+GPIO pins are shared with digital or analog alternate functions. All GPIOs are high current
+capable except for analog inputs.
+
+Default Zephyr Peripheral Mapping:
+----------------------------------
+
+- UART_3 TX/RX       : PC10/PC11 (ST-Link Virtual Port Com)
+- BUTTON (JOY_SEL)   : PC0
+- BUTTON (JOY_LEFT)  : PC1
+- BUTTON (JOY_DOWN)  : PC2
+- BUTTON (JOY_RIGHT) : PC3
+- BUTTON (JOY_UP)    : PC4
+- LED (TO_REC)       : PD9
+- LED (TO_PLUG)      : PD8
+- LED (SINK_SPY)     : PD5
+- LED (SOURCE)       : PC12
+
+For mode details please refer to `STM32G0 Discovery board User Manual`_.
+
+Programming and Debugging
+*************************
+
+Applications for the ``stm32g071b_disco`` board configuration can be built and
+flashed in the usual way (see :ref:`build_an_application` and
+:ref:`application_run` for more details).
+
+Flashing
+========
+
+The STM32G071B Discovery board includes an ST-LINK/V2-1 embedded debug tool interface.
+
+.. code-block:: console
+
+   $ west flash
+
+Flashing an application to the STM32G071B_DISCO
+-----------------------------------------------
+
+Here is an example for the :ref:`blinky-sample` application.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/basic/blinky
+   :board: stm32g071b_disco
+   :goals: build flash
+
+You will see the LED blinking every second.
+
+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: stm32g071b_disco
+   :maybe-skip-config:
+   :goals: debug
+
+References
+**********
+
+.. target-notes::
+
+.. _STM32G071B-DISCO website:
+   https://www.st.com/en/evaluation-tools/stm32g071b-disco.html
+
+.. _STM32G071 reference manual:
+   http://www.st.com/resource/en/reference_manual/dm00371828.pdf
+
+.. _STM32G0 Discovery board User Manual:
+   https://www.st.com/resource/en/user_manual/dm00496511.pdf
+
+.. _G071RB on www.st.com:
+   http://www.st.com/en/microcontrollers/stm32g071rb.html

boards/arm/stm32g071b_disco/stm32g071b_disco.dts

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+/*
+ * Copyright 2021 The Chromium OS Authors
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+#include <st/g0/stm32g071Xb.dtsi>
+#include <st/g0/stm32g071r(6-8-b)tx-pinctrl.dtsi>
+
+/ {
+	model = "STM32G071B DEMO board";
+	compatible = "st,stm32g071-demo";
+
+	chosen {
+		zephyr,console = &usart3;
+		zephyr,shell-uart = &usart3;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+		red_led_4: led4 {
+			gpios = <&gpiod 9 GPIO_ACTIVE_HIGH>;
+			label = "TO_REC";
+		};
+		red_led_5: led5 {
+			gpios = <&gpiod 8 GPIO_ACTIVE_HIGH>;
+			label = "TO_PLUG";
+		};
+		green_led_6: led6 {
+			gpios = <&gpiod 5 GPIO_ACTIVE_HIGH>;
+			label = "SINK_SPY";
+		};
+		green_led_7: led7 {
+			gpios = <&gpioc 12 GPIO_ACTIVE_HIGH>;
+			label = "SOURCE";
+		};
+	};
+
+	gpio_keys {
+		compatible = "gpio-keys";
+		joy_sel: button0 {
+			label = "JOY_SEL";
+			gpios = <&gpioc 0 (GPIO_ACTIVE_HIGH | GPIO_PULL_DOWN)>;
+		};
+		joy_left: button1 {
+			label = "JOY_LEFT";
+			gpios = <&gpioc 1 (GPIO_ACTIVE_HIGH | GPIO_PULL_DOWN)>;
+		};
+		joy_down: button2 {
+			label = "JOY_DOWN";
+			gpios = <&gpioc 2 (GPIO_ACTIVE_HIGH | GPIO_PULL_DOWN)>;
+		};
+		joy_right: button3 {
+			label = "JOY_RIGHT";
+			gpios = <&gpioc 3 (GPIO_ACTIVE_HIGH | GPIO_PULL_DOWN)>;
+		};
+		joy_up: button4 {
+			label = "JOY_UP";
+			gpios = <&gpioc 4 (GPIO_ACTIVE_HIGH | GPIO_PULL_DOWN)>;
+		};
+	};
+
+	aliases {
+		led0 = &red_led_4;
+		led1 = &red_led_5;
+		led2 = &green_led_6;
+		led3 = &green_led_7;
+		sw0 = &joy_sel;
+		sw1 = &joy_left;
+		sw2 = &joy_down;
+		sw3 = &joy_right;
+		sw4 = &joy_up;
+	};
+};
+
+&usart3 {
+	pinctrl-0 = <&usart3_tx_pc10 &usart3_rx_pc11>;
+	current-speed = <115200>;
+	status = "okay";
+};
+
+&iwdg {
+	status = "okay";
+};

boards/arm/stm32g071b_disco/stm32g071b_disco.yaml

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+identifier: stm32g071b_disco
+name: ST STM32G071B Discovery
+type: mcu
+arch: arm
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools
+ram: 36
+flash: 128
+supported:
+  - uart
+  - gpio
+  - watchdog

boards/arm/stm32g071b_disco/stm32g071b_disco_defconfig

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+# Copyright 2021 The Chromium OS Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_SOC_SERIES_STM32G0X=y
+CONFIG_SOC_STM32G071XX=y
+
+# 64MHz system clock
+CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=64000000
+
+# 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
+
+# Clock configuration
+CONFIG_CLOCK_CONTROL=y
+
+# SYSCLK selection
+CONFIG_CLOCK_STM32_SYSCLK_SRC_PLL=y
+
+# PLL configuration
+CONFIG_CLOCK_STM32_PLL_SRC_HSI=y
+
+# produce 64MHz clock at PLL output
+CONFIG_CLOCK_STM32_PLL_M_DIVISOR=1
+CONFIG_CLOCK_STM32_PLL_N_MULTIPLIER=8
+CONFIG_CLOCK_STM32_PLL_P_DIVISOR=2
+CONFIG_CLOCK_STM32_PLL_Q_DIVISOR=2
+CONFIG_CLOCK_STM32_PLL_R_DIVISOR=2
+CONFIG_CLOCK_STM32_AHB_PRESCALER=1
+CONFIG_CLOCK_STM32_APB1_PRESCALER=1