board: arm: add support for the nucleo_f303k8 board

This branch adds support for the nucleo_f303k8 board.
The configuration is based on the nucleo_l011k4,
the f302r8 and the ST reference manual.

I had successfully tested the following sample code:
blinky
blink_led (uses TIM2_CH1 on PA0)
button
hello_world

Signed-off-by: Sebastian Schwabe <sebastian.schwabe@mailbox.tu-dresden.de>

boards/arm/nucleo_f303k8/Kconfig.board

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+# NUCLEO-32 F303k8 board configuration
+
+# Copyright (c) 2020 Sebastian Schwabe <sebastian.schwabe@mailbox.tu-dresden.de>
+#                    	Fabian Paschke <fabian.paschke@eas.iis.fraunhofer.de>
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_NUCLEO_F303K8
+	bool "NUCLEO-32 F303K8 Development Board"
+	depends on SOC_STM32F303X8

boards/arm/nucleo_f303k8/Kconfig.defconfig

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+# NUCLEO-32 F303k8 board configuration
+
+# Copyright (c) 2020 Sebastian Schwabe <sebastian.schwabe@mailbox.tu-dresden.de>
+#                    	Fabian Paschke <fabian.paschke@eas.iis.fraunhofer.de>
+# SPDX-License-Identifier: Apache-2.0
+
+if BOARD_NUCLEO_F303K8
+
+config BOARD
+	default "nucleo_f303k8"
+
+endif # BOARD_NUCLEO_F303K8

boards/arm/nucleo_f303k8/board.cmake

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+# SPDX-License-Identifier: Apache-2.0
+
+board_runner_args(jlink "--device=STM32F303K8" "--speed=4000")
+
+include(${ZEPHYR_BASE}/boards/common/openocd.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/jlink.board.cmake)

boards/arm/nucleo_f303k8/doc/index.rst

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+.. _nucleo_f303k8_board:
+
+ST Nucleo F303K8
+################
+
+Overview
+********
+
+The Nucleo F303K8 board features an ARM Cortex-M4 based STM32F303K8
+mixed-signal MCU with FPU and DSP instructions capable of running at 72 MHz.
+Here are some highlights of the Nucleo F303K8 board:
+
+- STM32 microcontroller in LQFP32 package
+- one type of extension resources:
+
+- Arduino™ Nano V3 connectivity support
+
+- On-board ST-LINK/V2-1 debugger/programmer with SWD connector
+- Flexible board power supply:
+
+- 5 V from ST-LINK/V2-1 USB VBUS
+- External power sources: 3.3 V, 5V and 7 - 12 V
+
+- One user LED
+- One push-buttons: RESET
+
+.. image:: img/nucleo_f303k8.jpg
+   :width: 500px
+   :height: 367px
+   :align: center
+   :alt: Nucleo F303K8
+
+More information about the board can be found at the `Nucleo F303K8 website`_,
+and in the `STM32 Nucleo-32 board User Manual`_.
+
+Hardware
+********
+
+The Nucleo F303K8 provides the following hardware components:
+
+- STM32F303K8T6 in LQFP32 package
+- ARM |reg| 32-bit Cortex |reg| -M4 CPU with FPU
+- 72 MHz max CPU frequency
+- VDD from 2.0 V to 3.6 V
+- 64 MB Flash
+- 12 KB SRAM
+- RTC
+- Advanced-control Timer
+- General Purpose Timers (5)
+- Basic Timer (2)
+- Watchdog Timers (2)
+- PWM channels (12)
+- SPI/I2S (1)
+- I2C (1)
+- USART/UART (2)
+- CAN (1)
+- GPIO with external interrupt capability
+- DMA channels (7)
+- Capacitive sensing channels (18)
+- 12-bit ADC with 21 channels
+- 12-bit D/A converter
+- Analog comparator (3)
+- Op amp
+
+
+More information about the STM32F303K8 can be found here:
+
+- `STM32F303K8 on www.st.com`_
+- `STM32F303K8 reference manual`_
+- `STM32F303K8 datasheet`_
+
+Supported Features
+==================
+
+The Zephyr nucleo_f303k8 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               |
++-----------+------------+-------------------------------------+
+| PINMUX    | on-chip    | pinmux                              |
++-----------+------------+-------------------------------------+
+| GPIO      | on-chip    | gpio                                |
++-----------+------------+-------------------------------------+
+| PWM       | on-chip    | pwm                                 |
++-----------+------------+-------------------------------------+
+| I2C       | on-chip    | i2c                                 |
++-----------+------------+-------------------------------------+
+| SPI       | on-chip    | spi                                 |
++-----------+------------+-------------------------------------+
+| ADC       | on-chip    | ADC Controller                      |
++-----------+------------+-------------------------------------+
+
+Other hardware features are not yet supported on this Zephyr port.
+
+The default configuration can be found in the defconfig file:
+``boards/arm/nucleo_f303k8/nucleo_f303k8_defconfig``
+
+Connections and IOs
+===================
+
+The Nucleo F303K8 Board has 1 GPIO controller. This controllers is responsible
+for input/output, pull-up, etc.
+
+Board connectors:
+-----------------
+.. image:: img/nucleo_f303k8_pinout.png
+   :width: 800px
+   :align: center
+   :height: 619px
+   :alt: Nucleo F303K8 connectors
+
+Default Zephyr Peripheral Mapping:
+----------------------------------
+
+The Nucleo F303K8 board features an Arduino Zero V3 connector. Board is configured as follows:
+
+- UART_2 TX/RX : PA2/PA15 (ST-Link Virtual Port Com)
+- I2C1 SCL/SDA : PB7/PB6
+- SPI1 CS/SCK/MISO/MOSI : PA_4/PA_5/PB_4/PA_7
+- LD2       : PB3
+
+System Clock
+------------
+
+The Nucleo F303K8 System Clock can be driven by an internal or
+external oscillator, as well as by the main PLL clock. By default the
+System Clock is driven by the PLL clock at 72 MHz. The input to the
+PLL is an 8 MHz internal clock supply.
+
+Serial Port
+-----------
+
+The Nucleo F303K8 board has 2 UARTs. The Zephyr console output is assigned
+to UART2.  Default settings are 115200 8N1.
+
+
+Programming and Debugging
+*************************
+
+The Nucleo F303K8 board includes an ST-LINK/V2-1 embedded debug tool interface.
+This interface is supported by the openocd version included in Zephyr SDK.
+
+
+.. _Nucleo F303K8 website:
+   http://www.st.com/en/evaluation-tools/nucleo-F303K8.html
+
+.. _STM32 Nucleo-32 board User Manual:
+   https://www.st.com/resource/en/user_manual/dm00231744-stm32-nucleo32-boards-mb1180-stmicroelectronics.pdf
+
+.. _STM32F303K8 on www.st.com:
+   http://www.st.com/en/microcontrollers/stm32F303K8.html
+
+.. _STM32F303K8 reference manual:
+   https://www.st.com/resource/en/reference_manual/dm00043574-stm32f303xbcde-stm32f303x68-stm32f328x8-stm32f358xc-stm32f398xe-advanced-armbased-mcus-stmicroelectronics.pdf
+
+.. _STM32F303K8 datasheet:
+   https://www.st.com/resource/en/datasheet/stm32f303k8.pdf

boards/arm/nucleo_f303k8/nucleo_f303k8.dts

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+/*
+ * Copyright (c) 2020 Sebastian Schwabe <sebastian.schwabe@mailbox.tu-dresden.de>
+ *                    Fabian Paschke <fabian.paschke@eas.iis.fraunhofer.de>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+#include <st/f3/stm32f303X8.dtsi>
+#include <st/f3/stm32f303k(6-8)tx-pinctrl.dtsi>
+
+/ {
+	model = "STMicroelectronics STM32F303K8-NUCLEO board";
+	compatible = "st,stm32f303k8-nucleo";
+
+	chosen {
+		zephyr,console = &usart2;
+		zephyr,shell-uart = &usart2;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+		green_led_3: green_led_3 {
+			gpios = <&gpiob 3 GPIO_ACTIVE_HIGH>;
+			label = "LD3";
+		};
+	};
+	pwmleds {
+		compatible = "pwm-leds";
+		green_pwm_led: green_pwm_led {
+			pwms = <&pwm2 2 0 PWM_POLARITY_NORMAL>;
+		};
+	};
+
+	aliases {
+		led0 = &green_led_3;
+		pwm-led0 = &green_pwm_led;
+	};
+};
+
+&timers2 {
+	status = "okay";
+
+	pwm2: pwm {
+		status = "okay";
+		pinctrl-0 = <&tim2_ch2_pb3>;
+	};
+};
+
+&usart2 {
+	pinctrl-0 = <&usart2_tx_pa2 &usart2_rx_pa15>;
+	current-speed = <115200>;
+	status = "okay";
+};
+
+
+&i2c1 {
+	pinctrl-0 = <&i2c1_scl_pb6 &i2c1_sda_pb7>;
+	status = "okay";
+	clock-frequency = <I2C_BITRATE_FAST>;
+};
+
+&spi1 {
+	pinctrl-0 = <&spi1_nss_pa4 &spi1_sck_pa5
+		     &spi1_miso_pa6 &spi1_mosi_pa7>;
+	status = "okay";
+};
+
+&adc1 {
+	pinctrl-0 = <&adc1_in1_pa0>;
+	status = "okay";
+};
+
+&rtc {
+	status = "okay";
+};

boards/arm/nucleo_f303k8/nucleo_f303k8.yaml

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+identifier: nucleo_f303k8
+name: ST Nucleo F303k8
+type: mcu
+arch: arm
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools
+ram: 12
+flash: 64
+supported:
+  - i2c
+  - spi
+  - gpio
+  - pwm
+  - counter

boards/arm/nucleo_f303k8/nucleo_f303k8_defconfig

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+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_SOC_SERIES_STM32F3X=y
+CONFIG_SOC_STM32F303X8=y
+# 72 MHz system clock
+CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=72000000
+
+CONFIG_SERIAL=y
+
+# console
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y
+
+# enable pinmux
+CONFIG_PINMUX=y
+
+# enable GPIO
+CONFIG_GPIO=y
+
+# clock configuration
+CONFIG_CLOCK_CONTROL=y
+
+# Clock configuration for Cube Clock control driver
+CONFIG_CLOCK_STM32_SYSCLK_SRC_PLL=y
+# use HSI as PLL input
+CONFIG_CLOCK_STM32_PLL_SRC_HSI=y
+# however, the board does not have an external oscillator, so just use
+# the 8MHz clock signal coming from integrated STLink
+# produce 72MHz clock at PLL output
+CONFIG_CLOCK_STM32_PLL_PREDIV=1
+CONFIG_CLOCK_STM32_PLL_MULTIPLIER=9
+CONFIG_CLOCK_STM32_AHB_PRESCALER=1
+CONFIG_CLOCK_STM32_APB1_PRESCALER=2
+CONFIG_CLOCK_STM32_APB2_PRESCALER=1

boards/arm/nucleo_f303k8/support/openocd.cfg

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+source [find board/st_nucleo_f3.cfg]
+
+$_TARGETNAME configure -event gdb-attach {
+        echo "Debugger attaching: halting execution"
+        reset halt
+        gdb_breakpoint_override hard
+}
+
+$_TARGETNAME configure -event gdb-detach {
+        echo "Debugger detaching: resuming execution"
+        resume
+}