boards: arm: add support for NUCLEO-L011K4 board

Support for the NUCLEO-L011K4 development board with STM32L011K4 SoC.

Although the SoC only contains 16K flash and 2K RAM, it has been tested
on a number of samples and has worked as expected.

Signed-off-by: Steven Daglish <s.c.daglish@gmail.com>

boards/arm/nucleo_l011k4/CMakeLists.txt

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+# SPDX-License-Identifier: Apache-2.0
+
+if(CONFIG_PINMUX)
+zephyr_library()
+zephyr_library_sources(pinmux.c)
+zephyr_library_include_directories(${ZEPHYR_BASE}/drivers)
+endif()

boards/arm/nucleo_l011k4/Kconfig.board

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+# STM32 Nucleo-32 development board with STM32L011K4 MCU configuration
+
+# Copyright (c) 2020 Steven Daglish <s.c.daglish@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_NUCLEO_L011K4
+	bool "NUCLEO-32 L011K4 Development Board"
+	depends on SOC_STM32L011XX

boards/arm/nucleo_l011k4/Kconfig.defconfig

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+# STM32 Nucleo-32 development board with STM32L011K4 MCU
+
+# Copyright (c) 2020 Steven Daglish <s.c.daglish@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+if BOARD_NUCLEO_L011K4
+
+config BOARD
+	default "nucleo_l011k4"
+
+config SPI_STM32_INTERRUPT
+	default y
+	depends on SPI
+
+endif # BOARD_NUCLEO_L011K4

boards/arm/nucleo_l011k4/board.cmake

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+# SPDX-License-Identifier: Apache-2.0
+
+board_runner_args(jlink "--device=STM32L011K4" "--speed=4000")
+
+include(${ZEPHYR_BASE}/boards/common/openocd.board.cmake)
+include(${ZEPHYR_BASE}/boards/common/jlink.board.cmake)

boards/arm/nucleo_l011k4/doc/index.rst

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+.. _nucleo_l011k4_board:
+
+ST Nucleo L011K4
+################
+
+Overview
+********
+The STM32 Nucleo-32 development board with STM32L011K4 MCU, supports Arduino Nano V3 connectivity.
+
+The STM32 Nucleo board provides an affordable, and flexible way for users to try out new concepts,
+and build prototypes with the STM32 microcontroller, choosing from the various
+combinations of performance, power consumption, and features.
+
+The Arduino* Nano V3 connectivity support allow easy functionality
+expansion of the STM32 Nucleo open development platform with a wide choice of
+specialized shields.
+
+The STM32 Nucleo board integrates the ST-LINK/V2-1 debugger and programmer.
+
+The STM32 Nucleo board comes with the STM32 comprehensive software HAL library together
+with various packaged software examples.
+
+.. image:: img/nucleo_l011k4.jpg
+   :width: 426px
+   :height: 319px
+   :align: center
+   :alt: Nucleo L011K4
+
+More information about the board can be found at the `Nucleo L011K4 website`_.
+
+Hardware
+********
+Nucleo L011K4 provides the following hardware components:
+
+- STM32 microcontroller in LQFP32 package
+- Extension resource:
+
+  - Arduino* Nano V3 connectivity
+
+- ARM* mbed*
+- On-board ST-LINK/V2-1 debugger/programmer with SWD connector:
+
+  - Selection-mode switch to use the kit as a standalone ST-LINK/V2-1
+
+- Flexible board power supply:
+
+  - USB VBUS or external source (3.3V, 5V, 7 - 12V)
+  - Power management access point
+
+- Three LEDs:
+
+  - USB communication (LD1), user LED (LD2), power LED (LD3)
+
+- One push-button: RESET
+- USB re-enumeration capability. Three different interfaces supported on USB:
+
+  - Virtual COM port
+  - Mass storage
+  - Debug port
+
+- Support of wide choice of Integrated Development Environments (IDEs) including:
+
+  - IAR
+  - ARM Keil
+  - GCC-based IDEs
+
+More information about STM32L011K4 can be found in the
+`STM32L0x1 reference manual`_
+
+
+Supported Features
+==================
+
+The Zephyr nucleo_l011k4 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                                |
++-----------+------------+-------------------------------------+
+| CLOCK     | on-chip    | reset and clock control             |
++-----------+------------+-------------------------------------+
+| I2C       | on-chip    | i2c controller                      |
++-----------+------------+-------------------------------------+
+| SPI       | on-chip    | spi controller                      |
++-----------+------------+-------------------------------------+
+| EEPROM    | on-chip    | eeprom                              |
++-----------+------------+-------------------------------------+
+
+Other hardware features are not yet supported in this Zephyr port.
+
+The default configuration can be found in the defconfig file:
+``boards/arm/nucleo_l011k4/nucleo_l011k4_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_2 TX/RX : PA2/PA15 (ST-Link Virtual Port Com)
+- I2C1 SCL/SDA : PA4/PA10 (Arduino I2C)
+- SPI1 SCK/MISO/MOSI : PA5/PA6/PA7 (Arduino SPI)
+- LD2       : PB3
+
+For mode details please refer to `STM32 Nucleo-32 board User Manual`_.
+
+Programming and Debugging
+*************************
+
+Applications for the ``nucleo_l011k4`` board configuration can be built and
+flashed in the usual way (see :ref:`build_an_application` and
+:ref:`application_run` for more details).
+
+Flashing
+========
+
+Nucleo L011K4 board includes an ST-LINK/V2-1 embedded debug tool interface.
+This interface is supported by the openocd version included in the Zephyr SDK.
+
+Flashing an application to Nucleo L011K4
+----------------------------------------
+
+Here is an example for the :ref:`blinky-sample` application.
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/basic/blinky
+   :board: nucleo_l011k4
+   :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: nucleo_l011k4
+   :maybe-skip-config:
+   :goals: debug
+
+References
+**********
+
+.. target-notes::
+
+.. _Nucleo L011K4 website:
+   http://www.st.com/en/evaluation-tools/nucleo-l011k4.html
+
+.. _STM32L0x1 reference manual:
+   https://www.st.com/resource/en/reference_manual/dm00108282-ultralowpower-stm32l0x1-advanced-armbased-32bit-mcus-stmicroelectronics.pdf
+
+.. _STM32 Nucleo-32 board User Manual:
+   https://www.st.com/resource/en/user_manual/dm00231744-stm32-nucleo32-boards-mb1180-stmicroelectronics.pdf

boards/arm/nucleo_l011k4/nucleo_l011k4.dts

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+/*
+ * Copyright (c) 2020 Steven Daglish <s.c.daglish@gmail.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+#include <st/l0/stm32l011X4.dtsi>
+#include <st/l0/stm32l011k(3-4)tx-pinctrl.dtsi>
+
+/ {
+	model = "STMicroelectronics STM32L011K4-NUCLEO board";
+	compatible = "st,stm32l011k4-nucleo";
+
+	chosen {
+		zephyr,console = &usart2;
+		zephyr,shell-uart = &usart2;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+		green_led_2: led_2 {
+			gpios = <&gpiob 3 GPIO_ACTIVE_HIGH>;
+			label = "User LD2";
+		};
+	};
+
+	gpio_keys {
+		compatible = "gpio-keys";
+		user_button: button {
+			label = "User";
+			gpios = <&gpioa 12 GPIO_ACTIVE_LOW>;
+		};
+	};
+
+	aliases {
+		led0 = &green_led_2;
+		eeprom-0 = &eeprom;
+	};
+};
+
+&usart2 {
+	pinctrl-0 = <&usart2_tx_pa2 &usart2_rx_pa15>;
+	current-speed = <115200>;
+	status = "okay";
+};
+
+&i2c1 {
+	pinctrl-0 = <&i2c1_scl_pa4 &i2c1_sda_pa10>;
+	status = "okay";
+	clock-frequency = <I2C_BITRATE_FAST>;
+};
+
+&spi1 {
+	status = "okay";
+};
+
+&eeprom {
+	status = "okay";
+};

boards/arm/nucleo_l011k4/nucleo_l011k4.yaml

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+identifier: nucleo_l011k4
+name: ST Nucleo L011K4
+type: mcu
+arch: arm
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools
+supported:
+  - gpio
+  - i2c
+  - spi
+  - eeprom
+ram: 2
+flash: 16

boards/arm/nucleo_l011k4/nucleo_l011k4_defconfig

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+# SPDX-License-Identifier: Apache-2.0
+
+# Zephyr Kernel Configuration
+CONFIG_SOC_SERIES_STM32L0X=y
+
+# Platform Configuration
+CONFIG_SOC_STM32L011XX=y
+
+# General Kernel Options
+CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=32000000
+
+# Kernel Options due to Low Memory (2k)
+CONFIG_MAIN_STACK_SIZE=320
+CONFIG_IDLE_STACK_SIZE=100
+CONFIG_ISR_STACK_SIZE=256
+
+# 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 32MHz clock at PLL output
+CONFIG_CLOCK_STM32_PLL_MULTIPLIER=4
+CONFIG_CLOCK_STM32_PLL_DIVISOR=2
+CONFIG_CLOCK_STM32_AHB_PRESCALER=1
+CONFIG_CLOCK_STM32_APB1_PRESCALER=1
+CONFIG_CLOCK_STM32_APB2_PRESCALER=1

boards/arm/nucleo_l011k4/pinmux.c

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+/*
+ * Copyright (c) 2020 Steven Daglish <s.c.daglish@gmail.com>
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <kernel.h>
+#include <device.h>
+#include <init.h>
+#include <drivers/pinmux.h>
+#include <sys/sys_io.h>
+
+#include <pinmux/stm32/pinmux_stm32.h>
+
+/* pin assignments for NUCLEO-L011K4 board */
+static const struct pin_config pinconf[] = {
+#if DT_NODE_HAS_STATUS(DT_NODELABEL(spi1), okay) && CONFIG_SPI
+	{STM32_PIN_PA5, STM32L0_PINMUX_FUNC_PA5_SPI1_SCK},
+	{STM32_PIN_PA6, STM32L0_PINMUX_FUNC_PA6_SPI1_MISO},
+	{STM32_PIN_PA7, STM32L0_PINMUX_FUNC_PA7_SPI1_MOSI},
+#endif
+};
+
+static int pinmux_stm32_init(const struct device *port)
+{
+	ARG_UNUSED(port);
+
+	stm32_setup_pins(pinconf, ARRAY_SIZE(pinconf));
+
+	return 0;
+}
+
+SYS_INIT(pinmux_stm32_init, PRE_KERNEL_1,
+	 CONFIG_PINMUX_STM32_DEVICE_INITIALIZATION_PRIORITY);

boards/arm/nucleo_l011k4/support/openocd.cfg

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+# This is an ST NUCLEO-L011K4 board with single STM32L011K4 chip.
+# http://www.st.com/en/evaluation-tools/nucleo-l011k4.html
+source [find interface/stlink.cfg]
+
+transport select hla_swd
+
+#set WORKAREASIZE 0x2000
+
+source [find target/stm32l0.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
+}