board: samc21: add support for SAMC21N Xplained Pro Board

Add basic support board with SAMC21N soc including SPI, UART, I2C,
ADC, Flash, Leds.

Signed-off-by: Kamil Serwus <kserwus@gmail.com>

boards/arm/atsamc21n_xpro/Kconfig.board

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+# SAM C21N Xplained Pro Board configuration
+
+# Copyright (c) 2022 Kamil Serwus
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_ATSAMC21N_XPRO
+	bool "SAM C21N Xplained Pro"
+	depends on SOC_PART_NUMBER_SAMC21N18A

boards/arm/atsamc21n_xpro/Kconfig.defconfig

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+# SAM C21N Xplained Pro board configuration
+
+# Copyright (c) 2022 Kamil Serwus
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD
+	default "atsamc21n_xpro"
+	depends on BOARD_ATSAMC21N_XPRO

boards/arm/atsamc21n_xpro/atsamc21n_xpro-pinctrl.dtsi

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+/*
+ * Copyright (c) 2022 Kamil Serwus
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <dt-bindings/pinctrl/samc21n-pinctrl.h>
+
+&pinctrl {
+
+	pwm_default: pwm_default {
+		group1 {
+			pinmux = <PC5F_TCC2_WO1>;
+		};
+	};
+
+	adc0_default: adc0_default {
+		group1 {
+			pinmux = <PB9B_ADC0_AIN3>;
+		};
+	};
+
+	adc1_default: adc1_default {
+		group1 {
+			pinmux = <PA8B_ADC1_AIN10>;
+		};
+	};
+
+	sercom0_uart_default: sercom0_uart_default {
+		group1 {
+			pinmux = <PB25C_SERCOM0_PAD1>,
+				 <PB24C_SERCOM0_PAD0>;
+		};
+	};
+
+	sercom1_i2c_default: sercom1_i2c_default {
+		group1 {
+			pinmux = <PA16C_SERCOM1_PAD0>,
+				 <PA17C_SERCOM1_PAD1>;
+		};
+	};
+
+	sercom2_uart_default: sercom1_uart_default {
+		group1 {
+			pinmux = <PA13C_SERCOM2_PAD1>,
+				 <PA12C_SERCOM2_PAD0>;
+		};
+	};
+
+	sercom4_uart_default: sercom4_uart_default {
+		group1 {
+			pinmux = <PB11D_SERCOM4_PAD3>,
+				 <PB10D_SERCOM4_PAD2>;
+		};
+	};
+
+	sercom5_spi_default: sercom5_spi_default {
+		group1 {
+			pinmux = <PB0D_SERCOM5_PAD2>,
+				 <PB2D_SERCOM5_PAD0>,
+				 <PB1D_SERCOM5_PAD3>;
+		};
+	};
+
+};

boards/arm/atsamc21n_xpro/atsamc21n_xpro.dts

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+/*
+ * Copyright (c) 2022 Kamil Serwus
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+
+#include <atmel/samc21x18.dtsi>
+#include "atsamc21n_xpro-pinctrl.dtsi"
+
+/ {
+	model = "SAM C21N Xplained Pro";
+	compatible = "atsamc21n,xpro", "atmel,samc21n18a", "atmel,samc21";
+
+	chosen {
+		zephyr,console = &sercom4;
+		zephyr,shell-uart = &sercom4;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+	};
+
+	/* These aliases are provided for compatibility with samples */
+	aliases {
+		led0 = &led0;
+		pwm-led0 = &pwm_led0;
+		sw0 = &user_button;
+		i2c-0 = &sercom1;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+		led0: led_0 {
+			gpios = <&portc 05 GPIO_ACTIVE_LOW>;
+			label = "Yellow LED";
+		};
+	};
+
+	pwmleds {
+		compatible = "pwm-leds";
+		pwm_led0: pwm_led_0 {
+			pwms = <&tcc2 1 PWM_MSEC(20)>;
+		};
+	};
+
+	buttons {
+		compatible = "gpio-keys";
+		user_button: button_0 {
+			gpios = <&portb 19 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
+			label = "User Button";
+		};
+	};
+
+};
+
+&cpu0 {
+	clock-frequency = <48000000>;
+};
+
+&adc0 {
+	status = "okay";
+	pinctrl-0 = <&adc0_default>;
+	pinctrl-names = "default";
+};
+
+&adc1 {
+	pinctrl-0 = <&adc1_default>;
+	pinctrl-names = "default";
+};
+
+&tcc2 {
+	status = "okay";
+	compatible = "atmel,sam0-tcc-pwm";
+	prescaler = <256>;
+	#pwm-cells = <2>;
+
+	pinctrl-0 = <&pwm_default>;
+	pinctrl-names = "default";
+};
+
+&sercom0 {
+	status = "okay";
+	compatible = "atmel,sam0-uart";
+	current-speed = <9600>;
+	rxpo = <1>;
+	txpo = <0>;
+
+	pinctrl-0 = <&sercom0_uart_default>;
+	pinctrl-names = "default";
+};
+
+&sercom1 {
+	status = "okay";
+	compatible = "atmel,sam0-i2c";
+	clock-frequency = <I2C_BITRATE_FAST>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	pinctrl-0 = <&sercom1_i2c_default>;
+	pinctrl-names = "default";
+};
+
+&sercom2 {
+	status = "okay";
+	compatible = "atmel,sam0-uart";
+	current-speed = <115200>;
+	rxpo = <1>;
+	txpo = <0>;
+
+	pinctrl-0 = <&sercom2_uart_default>;
+	pinctrl-names = "default";
+};
+
+&sercom4 {
+	status = "okay";
+	compatible = "atmel,sam0-uart";
+	current-speed = <115200>;
+	rxpo = <3>;
+	txpo = <1>;
+
+	pinctrl-0 = <&sercom4_uart_default>;
+	pinctrl-names = "default";
+};
+
+&sercom5 {
+	status = "okay";
+	compatible = "atmel,sam0-spi";
+	dipo = <0>;
+	dopo = <2>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	pinctrl-0 = <&sercom5_spi_default>;
+	pinctrl-names = "default";
+};
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		/*
+		 * The final 16 KiB is reserved for the application.
+		 * Storage partition will be used by FCB/LittleFS/NVS
+		 * if enabled.
+		 */
+		storage_partition: partition@3c000 {
+			label = "storage";
+			reg = <0x0003c000 0x00004000>;
+		};
+	};
+};

boards/arm/atsamc21n_xpro/atsamc21n_xpro.yaml

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+# Copyright (c) 2022 Kamil Serwus
+# SPDX-License-Identifier: Apache-2.0
+identifier: atsamc21n_xpro
+name: SAM C21N Xplained Pro
+type: mcu
+arch: arm
+ram: 32
+flash: 256
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools
+supported:
+  - adc
+  - gpio
+  - i2c
+  - pwm
+  - spi

boards/arm/atsamc21n_xpro/atsamc21n_xpro_defconfig

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+# Copyright (c) 2022 Kamil Serwus
+# SPDX-License-Identifier: Apache-2.0
+CONFIG_SOC_SERIES_SAMC21=y
+CONFIG_SOC_PART_NUMBER_SAMC21N18A=y
+CONFIG_BOARD_ATSAMC21N_XPRO=y
+CONFIG_BUILD_OUTPUT_HEX=y
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y
+CONFIG_SERIAL=y
+CONFIG_UART_INTERRUPT_DRIVEN=y
+CONFIG_GPIO=y

boards/arm/atsamc21n_xpro/board.cmake

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+# Copyright (c) 2022 Kamil Serwus
+# SPDX-License-Identifier: Apache-2.0
+
+include(${ZEPHYR_BASE}/boards/common/openocd.board.cmake)

boards/arm/atsamc21n_xpro/doc/index.rst

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+.. _atsamc21n_xpro:
+
+SAM C21N Xplained Pro Evaluation Kit
+####################################
+
+Overview
+********
+
+The SAM C21N Xplained Pro evaluation kit is ideal for evaluation and
+prototyping with the SAM C21N Cortex®-M0+ processor-based
+microcontrollers. The kit includes Atmel’s Embedded Debugger (EDBG),
+which provides a full debug interface without the need for additional
+hardware.
+
+.. image:: img/atsamc21n_xpro.jpg
+     :align: center
+     :alt: ATSAMC21N-XPRO
+
+Hardware
+********
+
+- ATSAMC21N18A ARM Cortex-M0+ processor at 48 MHz
+- 32.768 kHz crystal oscillator
+- 256 KiB flash memory, 32 KiB of RAM, 8KB RRW flash
+- One yellow user LED
+- One mechanical user push button
+- One reset button
+- One QTouch® button
+- On-board USB based EDBG unit with serial console
+- Two CAN transceivers
+
+Supported Features
+==================
+
+The atsamc21n_xpro board configuration supports the following hardware
+features:
+
+.. list-table::
+    :header-rows: 1
+
+    * - Interface
+      - Controller
+      - Driver / Component
+    * - NVIC
+      - on-chip
+      - nested vector interrupt controller
+    * - Flash
+      - on-chip
+      - Can be used with LittleFS to store files
+    * - SYSTICK
+      - on-chip
+      - systick
+    * - WDT
+      - on-chip
+      - Watchdog
+    * - ADC
+      - on-chip
+      - Analog to Digital Converter
+    * - GPIO
+      - on-chip
+      - I/O ports
+    * - PWM
+      - on-chip
+      - Pulse Width Modulation
+    * - USART
+      - on-chip
+      - Serial ports
+    * - I2C
+      - on-chip
+      - I2C ports
+    * - SPI
+      - on-chip
+      - Serial Peripheral Interface ports
+
+Other hardware features are not currently supported by Zephyr.
+
+The default configuration can be found in the Kconfig
+``boards/arm/atsamc21n_xpro/atsamc21n_xpro_defconfig``.
+
+Pin Mapping
+===========
+
+The SAM C21N Xplained Pro evaluation kit has 4 GPIO controllers. These
+controllers are responsible for pin muxing, input/output, pull-up, etc.
+
+For mode details please refer to `SAM C21 Family Datasheet`_ and the `SAM C21N
+Xplained Pro Schematic`_.
+
+Default Zephyr Peripheral Mapping:
+----------------------------------
+- ADC0             : PB09
+- ADC1             : PA08
+- SERCOM0 USART TX : PB24
+- SERCOM0 USART RX : PB25
+- SERCOM1 I2C SDA  : PA16
+- SERCOM1 I2C SCL  : PA17
+- SERCOM2 USART TX : PA12
+- SERCOM2 USART RX : PA13
+- SERCOM4 USART TX : PB10
+- SERCOM4 USART RX : PB11
+- SERCOM5 SPI MISO : PB00
+- SERCOM5 SPI MOSI : PB02
+- SERCOM5 SPI SCK  : PB01
+- GPIO/PWM LED0    : PC05
+
+System Clock
+============
+
+The SAMC21 MCU is configured to use the 32.768 kHz internal oscillator
+with the on-chip internal oscillator generating the 48 MHz system clock.
+
+Serial Port
+===========
+
+The SAMC21 MCU has eight SERCOM based USARTs with three configured as USARTs in
+this BSP. SERCOM4 is the default Zephyr console.
+
+- SERCOM0 9600 8n1
+- SERCOM2 115200 8n1
+- SERCOM4 115200 8n1 connected to the onboard Atmel Embedded Debugger (EDBG)
+
+PWM
+===
+
+The SAMC21 MCU has 3 TCC based PWM units with up to 4 outputs each and a period
+of 24 bits or 16 bits.  If :code:`CONFIG_PWM_SAM0_TCC` is enabled then LED0 is
+driven by TCC2 instead of by GPIO.
+
+Programming and Debugging
+*************************
+
+The SAM C21N Xplained Pro comes with a Atmel Embedded Debugger (EDBG). This
+provides a debug interface to the SAMC21 chip and is supported by
+OpenOCD.
+
+Flashing
+========
+
+#. Build the Zephyr kernel and the ``hello_world`` sample application:
+
+   .. zephyr-app-commands::
+      :zephyr-app: samples/hello_world
+      :board: atsamc21n_xpro
+      :goals: build
+      :compact:
+
+#. Connect the SAM C21N Xplained Pro to your host computer using the USB debug
+   port.
+
+#. Run your favorite terminal program to listen for output. Under Linux the
+   terminal should be :code:`/dev/ttyACM0`. For example:
+
+   .. code-block:: console
+
+      $ minicom -D /dev/ttyACM0 -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: atsamc21n_xpro
+      :goals: flash
+      :compact:
+
+   You should see "Hello World! atsamc21n_xpro" in your terminal.
+
+References
+**********
+
+.. target-notes::
+
+.. _Microchip website:
+    https://www.microchip.com/en-us/development-tool/ATSAMC21N-XPRO
+
+.. _SAM C21 Family Datasheet:
+    https://ww1.microchip.com/downloads/aemDocuments/documents/MCU32/ProductDocuments/DataSheets/SAM-C20-C21-Family-Data-Sheet-DS60001479J.pdf
+
+.. _SAM C21N Xplained Pro Schematic:
+    https://ww1.microchip.com/downloads/en/DeviceDoc/ATSAMC21N_Xplained_Pro_Design_Files.zip

boards/arm/atsamc21n_xpro/pre_dt_board.cmake

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+# Copyright (c) 2021 Linaro Limited
+# SPDX-License-Identifier: Apache-2.0
+
+# Suppress "unique_unit_address_if_enabled" to handle the following overlaps:
+# - /soc/pinmux@41004400 & /soc/gpio@41004400
+# - /soc/pinmux@41004480 & /soc/gpio@41004480
+list(APPEND EXTRA_DTC_FLAGS "-Wno-unique_unit_address_if_enabled")

boards/arm/atsamc21n_xpro/support/openocd.cfg

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+# Copyright (c) 2018 Bryan O'Donoghue
+# Copyright (c) 2022 Kamil Serwus
+# SPDX-License-Identifier: Apache-2.0
+source [find interface/cmsis-dap.cfg]
+transport select swd
+
+# chip name
+set CHIPNAME at91samc21n18a
+set ENDIAN little
+set CPUTAPID 0x0bc11477
+
+source [find target/at91samdXX.cfg]
+
+reset_config trst_and_srst separate
+
+$_TARGETNAME configure -event gdb-attach {
+	echo "Debugger attaching: halting execution"
+	reset halt
+	gdb_breakpoint_override hard
+}
+
+$_TARGETNAME configure -event gdb-detach {
+	echo "Debugger detaching: resuming execution"
+	resume
+}

samples/drivers/adc/boards/atsamc21n_xpro.overlay

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+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Copyright (c) 2021 Argentum Systems Ltd.
+ */
+
+#include <zephyr/dt-bindings/adc/adc.h>
+
+/ {
+	zephyr,user {
+		/* EXT-1, pin 3 ADC(+) */
+		io-channels = <&adc0 3>;
+	};
+};
+
+&adc0 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	channel@3 {
+		reg = <3>;
+		zephyr,gain = "ADC_GAIN_1";
+		zephyr,reference = "ADC_REF_INTERNAL";
+		zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
+		zephyr,resolution = <12>;
+		zephyr,input-positive = <3>;
+	};
+};