boards: riscv: introduce gd32vf103c_starter board

add gd32vf103c_starter board.

Signed-off-by: YuLong Yao <feilongphone@gmail.com>

boards/riscv/gd32vf103c_starter/Kconfig.board

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+# Copyright (c) 2022 YuLong Yao <feilongphone@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_GD32VF103C_STARTER
+	bool "GigaDevice GD32VF103C-STARTER"
+	depends on SOC_GD32VF103

boards/riscv/gd32vf103c_starter/Kconfig.defconfig

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+# Copyright (c) 2022 YuLong Yao <feilongphone@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+if BOARD_GD32VF103C_STARTER
+
+config BOARD
+	default "gd32vf103c_starter"
+
+endif # BOARD_GD32VF103C_STARTER

boards/riscv/gd32vf103c_starter/board.cmake

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+# Copyright (c) 2022 YuLong Yao <feilongphone@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+board_runner_args(
+  jlink
+  "--device=GD32VF103CBT6" "--iface=jtag" "--tool-opt=-JTAGConf -1,-1"
+)
+
+include(${ZEPHYR_BASE}/boards/common/openocd.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/jlink.board.cmake)

boards/riscv/gd32vf103c_starter/doc/index.rst

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+.. _gd32vf103c_starter:
+
+GigaDevice GD32VF103C-STARTER
+#############################
+
+Overview
+********
+
+The GD32VF103C-STARTER board is a hardware platform that enables prototyping
+on GD32VF103CB RISC-V MCU.
+
+The GD32VF103CB features a single-core RISC-V 32-bit MCU which can run up
+to 108 MHz with flash accesses zero wait states, 128 KiB of Flash, 32 KiB of
+SRAM and 37 GPIOs.
+
+.. image:: img/gd32vf103c_starter.jpg
+     :align: center
+     :alt: gd32vf103c_starter
+
+Hardware
+********
+
+- GD32VF103CBT6 MCU
+- 1 x User LEDs
+- 1 x USART (USB port with CH340E)
+- USB FS connector
+- GD-Link on board programmer
+- J-Link/JTAG connector
+
+For more information about the GD32VF103 SoC and GD32VF103C-STARTER board:
+
+- `GigaDevice RISC-V Mainstream SoC Website`_
+- `GD32VF103 Datasheet`_
+- `GD32VF103 User Manual`_
+- `GD32VF103C-STARTER Documents`_
+
+Supported Features
+==================
+
+The board configuration supports the following hardware features:
+
+.. list-table::
+   :header-rows: 1
+
+   * - Peripheral
+     - Kconfig option
+     - Devicetree compatible
+   * - GPIO
+     - :kconfig:option:`CONFIG_GPIO`
+     - :dtcompatible:`gd,gd32-gpio`
+   * - Machine timer
+     - :kconfig:option:`CONFIG_RISCV_MACHINE_TIMER`
+     - :dtcompatible:`riscv,machine-timer`
+   * - Nuclei ECLIC Interrupt Controller
+     - :kconfig:option:`CONFIG_NUCLEI_ECLIC`
+     - :dtcompatible:`nuclei,eclic`
+   * - PWM
+     - :kconfig:option:`CONFIG_PWM`
+     - :dtcompatible:`gd,gd32-pwm`
+   * - USART
+     - :kconfig:option:`CONFIG_SERIAL`
+     - :dtcompatible:`gd,gd32-usart`
+
+Serial Port
+===========
+
+The GD32VF103C-STARTER board has one serial communications port.
+TX connected at PA9 and RX at PA10.
+
+Programming and Debugging
+*************************
+
+Before programming your board make sure to configure boot and serial jumpers
+as follows:
+
+- JP2/3: Select 2-3 for both (boot from user memory)
+- JP5/6: Select 1-2 positions (labeled as ``USART0``)
+
+Using GD-Link
+=============
+
+The GD32VF103C-STARTER includes an onboard programmer/debugger (GD-Link) which
+allows flash programming and debugging over USB. There is also a JTAG header
+(JP1) which can be used with tools like Segger J-Link.
+
+.. note::
+
+   The OpenOCD shipped with Zephyr SDK does not support GD32VF103. You will need
+   to build the `riscv-openocd fork <https://github.com/riscv/riscv-openocd>`_.
+   Note that compared with OpenOCD, J-Link offers a better programming and
+   debugging experience on this board.
+
+#. Build the Zephyr kernel and the :ref:`hello_world` sample application:
+
+   .. zephyr-app-commands::
+      :zephyr-app: samples/hello_world
+      :board: gd32vf103c_starter
+      :goals: build
+      :gen-args: -DOPENOCD=<path/to/riscv-openocd/bin/openocd> -DOPENOCD_DEFAULT_PATH=<path/to/riscv-openocd/share/openocd/scripts>
+      :compact:
+
+#. Run your favorite terminal program to listen for output. On Linux the
+   terminal should be something like ``/dev/ttyUSB0``. For example:
+
+   .. code-block:: console
+
+      minicom -D /dev/ttyUSB0 -o
+
+   The -o option tells minicom not to send the modem initialization
+   string. Connection should be configured as follows:
+
+      - Speed: 115200
+      - Data: 8 bits
+      - Parity: None
+      - Stop bits: 1
+
+#. To flash an image:
+
+   .. zephyr-app-commands::
+      :zephyr-app: samples/hello_world
+      :board: gd32vf103c_starter
+      :goals: flash
+      :compact:
+
+   You should see "Hello World! gd32vf103c_starter" in your terminal.
+
+#. To debug an image:
+
+   .. zephyr-app-commands::
+      :zephyr-app: samples/hello_world
+      :board: gd32vf103c_starter
+      :goals: debug
+      :compact:
+
+
+.. _GigaDevice RISC-V Mainstream SoC Website:
+   https://www.gigadevice.com/products/microcontrollers/gd32/risc-v/mainstream-line/
+
+.. _GD32VF103 Datasheet:
+   https://www.gigadevice.com/datasheet/gd32vf103xxxx-datasheet/
+
+.. _GD32VF103 User Manual:
+   http://www.gd32mcu.com/download/down/document_id/222/path_type/1
+
+.. _GD32VF103C-STARTER Documents:
+   https://github.com/riscv-mcu/GD32VF103_Demo_Suites/tree/master/GD32VF103C_START_Demo_Suites/Docs

boards/riscv/gd32vf103c_starter/gd32vf103c_starter-pinctrl.dtsi

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+/*
+ * Copyright (c) 2022 YuLong Yao <feilongphone@gmail.com>
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <dt-bindings/pinctrl/gd32vf103c(b-8)xx-pinctrl.h>
+
+&pinctrl {
+	usart0_default: usart0_default {
+		group1 {
+			pinmux = <USART0_RX_PA10_NORMP>, <USART0_TX_PA9_NORMP>;
+		};
+	};
+
+	pwm2_default: pwm2_default {
+		group1 {
+			pinmux = <TIMER2_CH1_PA7_OUT_NORMP>;
+		};
+	};
+};

boards/riscv/gd32vf103c_starter/gd32vf103c_starter.dts

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+/*
+ * Copyright (c) 2022 YuLong Yao <feilongphone@gmail.com>
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+
+#include <gigadevice/gd32vf103Xb.dtsi>
+#include "gd32vf103c_starter-pinctrl.dtsi"
+
+/ {
+	model = "GigaDevice GD32VF103C-STARTER";
+	compatible = "gd,gd32vf103c-starter";
+
+	chosen {
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+		zephyr,console = &usart0;
+		zephyr,shell-uart = &usart0;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+		led1: led1 {
+			gpios = <&gpioa 7 GPIO_ACTIVE_HIGH>;
+			label = "LED1";
+		};
+	};
+
+	gpio_keys {
+		compatible = "gpio-keys";
+		key_a: key_a {
+			label = "KEY_A";
+			gpios = <&gpioa 0 GPIO_ACTIVE_LOW>;
+		};
+	};
+
+	pwmleds {
+		compatible = "pwm-leds";
+
+		/* NOTE: pwm_led and led1 are share same pin (PA7). */
+		/* When CONFIG_PWM=y it can only be controlled using the PWM API. */
+		pwm_led: pwm_led {
+			pwms = <&pwm2 1 PWM_POLARITY_NORMAL>;
+		};
+	};
+
+	aliases {
+		led0 = &led1;
+		sw0 = &key_a;
+		pwm-led0 = &pwm_led;
+	};
+};
+
+&gpioa {
+	status = "okay";
+};
+
+&gpiob {
+	status = "okay";
+};
+
+&gpioc {
+	status = "okay";
+};
+
+&gpioe {
+	status = "okay";
+};
+
+&usart0 {
+	status = "okay";
+	current-speed = <115200>;
+	pinctrl-0 = <&usart0_default>;
+	pinctrl-names = "default";
+};
+
+&timer2 {
+	status = "okay";
+	prescaler = <128>;
+
+	pwm2: pwm {
+		status = "okay";
+		pinctrl-0 = <&pwm2_default>;
+		pinctrl-names = "default";
+	};
+};

boards/riscv/gd32vf103c_starter/gd32vf103c_starter.yaml

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+# Copyright (c) 2022 YuLong Yao <feilongphone@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+identifier: gd32vf103c_starter
+name: GigaDevice GD32VF103C-STARTER
+type: mcu
+arch: riscv32
+ram: 32
+flash: 128
+toolchain:
+  - zephyr
+supported:
+  - uart
+  - gpio
+  - pwm

boards/riscv/gd32vf103c_starter/gd32vf103c_starter_defconfig

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+# Copyright (c) 2022 YuLong Yao <feilongphone@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_SOC_SERIES_GD32VF103=y
+CONFIG_SOC_GD32VF103=y
+CONFIG_BOARD_GD32VF103C_STARTER=y
+
+CONFIG_GD32_HXTAL_8MHZ=y
+CONFIG_RISCV_MACHINE_TIMER=y

boards/riscv/gd32vf103c_starter/support/openocd.cfg

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+# Copyright (c) 2021, Teslabs Engineering S.L.
+# SPDX-License-Identifier: Apache-2.0
+
+# NOTE: This configuration file is intended to be used with the
+# https://github.com/riscv/riscv-openocd OpenOCD fork.
+
+source [find interface/cmsis-dap.cfg]
+source [find target/gd32vf103.cfg]