boards: Add support for Adafruit Feather M0 with LoRa radio

Add support for the Feather M0 LoRa board, including support of its
Semtech Lora radio. Tested the radio using a pair of boards.

Signed-off-by: Miguel Dardenne <miguel.dardenne@gmail.com>

boards/arm/adafruit_feather_m0_lora/Kconfig.board

@@ -0,0 +1,8 @@
+# Adafruit Feather M0 LoRa board configuration
+
+# Copyright (c) 2022 Miguel Dardenne <miguel.dardenne@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_ADAFRUIT_FEATHER_M0_LORA
+	bool "Adafruit Feather M0 LoRa"
+	depends on SOC_PART_NUMBER_SAMD21G18A

boards/arm/adafruit_feather_m0_lora/Kconfig.defconfig

@@ -0,0 +1,8 @@
+# Adafruit Feather M0 LoRa board configuration
+
+# Copyright (c) 2022 Miguel Dardenne <miguel.dardenne@gmail.com>
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD
+	default "adafruit_feather_m0_lora"
+	depends on BOARD_ADAFRUIT_FEATHER_M0_LORA

boards/arm/adafruit_feather_m0_lora/adafruit_feather_m0_lora-pinctrl.dtsi

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2022, Gerson Fernando Budke <nandojve@gmail.com>
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <dt-bindings/pinctrl/samd21-da1gXabcd-pinctrl.h>
+
+&pinctrl {
+	sercom3_i2c_default: sercom3_i2c_default {
+		group1 {
+			pinmux = <PA22C_SERCOM3_PAD0>,
+				 <PA23C_SERCOM3_PAD1>;
+		};
+	};
+
+	sercom4_spi_default: sercom4_spi_default {
+		group1 {
+			pinmux = <PA12D_SERCOM4_PAD0>,
+				 <PB10D_SERCOM4_PAD2>,
+				 <PB11D_SERCOM4_PAD3>;
+		};
+	};
+
+	sercom0_uart_default: sercom0_uart_default {
+		group1 {
+			pinmux = <PA11C_SERCOM0_PAD3>,
+				 <PA10C_SERCOM0_PAD2>;
+		};
+	};
+
+	usb_dc_default: usb_dc_default {
+		group1 {
+			pinmux = <PA25G_USB_DP>,
+				 <PA24G_USB_DM>;
+		};
+	};
+};

boards/arm/adafruit_feather_m0_lora/adafruit_feather_m0_lora.dts

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+/*
+ * Copyright (c) 2018 Henrik Brix Andersen <henrik@brixandersen.dk>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+#include <atmel/samd21.dtsi>
+#include "adafruit_feather_m0_lora-pinctrl.dtsi"
+#include "feather_connector.dtsi"
+
+/ {
+	model = "Adafruit Feather M0 LoRa";
+	compatible = "adafruit,feather-m0-lora", "atmel,samd21g18a",
+			"atmel,samd21";
+
+	chosen {
+		zephyr,console = &sercom0;
+		zephyr,shell-uart = &sercom0;
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+		zephyr,code-partition = &code_partition;
+	};
+
+	/* These aliases are provided for compatibility with samples */
+	aliases {
+		led0 = &led0;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+		led0: led_0 {
+			gpios = <&porta 17 0>;
+			label = "LED";
+		};
+	};
+};
+
+&cpu0 {
+	clock-frequency = <48000000>;
+};
+
+&sercom0 {
+	status = "okay";
+	compatible = "atmel,sam0-uart";
+	current-speed = <115200>;
+	rxpo = <3>;
+	txpo = <1>;
+
+	pinctrl-0 = <&sercom0_uart_default>;
+	pinctrl-names = "default";
+};
+
+&sercom3 {
+	status = "okay";
+	compatible = "atmel,sam0-i2c";
+	clock-frequency = <I2C_BITRATE_FAST>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	pinctrl-0 = <&sercom3_i2c_default>;
+	pinctrl-names = "default";
+};
+
+&sercom4 {
+	status = "okay";
+	compatible = "atmel,sam0-spi";
+	#address-cells = <1>;
+	#size-cells = <0>;
+	dipo = <0>;
+	dopo = <1>;
+
+	pinctrl-0 = <&sercom4_spi_default>;
+	pinctrl-names = "default";
+
+	cs-gpios = <&porta 6 GPIO_ACTIVE_LOW>;
+	lora: radio@0 {
+		reg = <0>;
+		compatible = "semtech,sx1276";
+		reset-gpios = <&porta 8 GPIO_ACTIVE_LOW>;
+		dio-gpios = <&porta 9 (GPIO_PULL_DOWN | GPIO_ACTIVE_HIGH)>;
+		spi-max-frequency = <10000000>;
+		power-amplifier-output = "pa-boost";
+	};
+};
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		boot_partition: partition@0 {
+			label = "sam-ba";
+			reg = <0x00000000 DT_SIZE_K(8)>;
+			read-only;
+		};
+
+		code_partition: partition@2000 {
+			label = "code";
+			reg = <0x2000 DT_SIZE_K(232)>;
+			read-only;
+		};
+
+		/*
+		 * 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 DT_SIZE_K(16)>;
+		};
+	};
+};
+
+&usb0 {
+	status = "okay";
+
+	pinctrl-0 = <&usb_dc_default>;
+	pinctrl-names = "default";
+};

boards/arm/adafruit_feather_m0_lora/adafruit_feather_m0_lora.yaml

@@ -0,0 +1,10 @@
+identifier: adafruit_feather_m0_lora
+name: Adafruit Feather M0 LoRa
+type: mcu
+arch: arm
+ram: 32
+flash: 232
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools

boards/arm/adafruit_feather_m0_lora/adafruit_feather_m0_lora_defconfig

@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_SOC_SERIES_SAMD21=y
+CONFIG_SOC_PART_NUMBER_SAMD21G18A=y
+CONFIG_BOARD_ADAFRUIT_FEATHER_M0_LORA=y
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y
+CONFIG_SERIAL=y
+CONFIG_UART_INTERRUPT_DRIVEN=y
+CONFIG_SOC_ATMEL_SAMD_XOSC32K=y
+CONFIG_SOC_ATMEL_SAMD_XOSC32K_AS_MAIN=y
+CONFIG_USE_DT_CODE_PARTITION=y

boards/arm/adafruit_feather_m0_lora/board.cmake

@@ -0,0 +1,5 @@
+# Copyright (c) 2018 Henrik Brix Andersen <henrik@brixandersen.dk>
+#
+# SPDX-License-Identifier: Apache-2.0
+
+include(${ZEPHYR_BASE}/boards/common/bossac.board.cmake)

boards/arm/adafruit_feather_m0_lora/doc/index.rst

@@ -0,0 +1,176 @@
+.. _adafruit_feather_m0_lora:
+
+Adafruit Feather M0 LoRa
+########################
+
+Overview
+********
+
+The Adafruit Feather M0 Lora is a thin, light ARM development
+boards with an onboard battery connector and charger for 3.7 V lithium
+polymer batteries, charging status indicator and user LEDs, native USB
+connector, 20 I/O pins, and a LoRa radio module from Semtech.
+
+.. image:: img/adafruit_feather_m0_lora.jpg
+     :align: center
+     :alt: Adafruit Feather M0 LoRa
+
+Hardware
+********
+
+- ATSAMD21G18A ARM Cortex-M0+ processor at 48 MHz
+- 32.768 kHz crystal oscillator
+- 256 KiB flash memory and 32 KiB of RAM
+- Battery connector and charger for 3.7 V lithium polymer batteries
+- Charging indicator LED
+- User LED
+- Reset button
+- Native USB port
+- SX127x LoRa radio
+
+Supported Features
+==================
+
+The adafruit_feather_m0_lora board configuration supports the
+following hardware features:
+
++-----------+------------+------------------------------------------+
+| 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                                 |
++-----------+------------+------------------------------------------+
+| GPIO      | on-chip    | I/O ports                                |
++-----------+------------+------------------------------------------+
+| USART     | on-chip    | Serial port                              |
++-----------+------------+------------------------------------------+
+| I2C       | on-chip    | Inter-Integrated Circuit                 |
++-----------+------------+------------------------------------------+
+| SPI       | on-chip    | Serial Peripheral Interface port         |
++-----------+------------+------------------------------------------+
+| USB       | on-chip    | USB device                               |
++-----------+------------+------------------------------------------+
+| RADIO     | SPI        | LoRa radio                               |
++-----------+------------+------------------------------------------+
+
+Other hardware features are not currently supported by Zephyr.
+
+The default configuration can be found in the Kconfig file
+:zephyr_file:`boards/arm/adafruit_feather_m0_lora/adafruit_feather_m0_lora_defconfig`.
+
+Connections and IOs
+===================
+
+The `Adafruit Feather M0 with LoRa radio module Learn site`_ has detailed
+information about the board including `pinouts`_ and the `schematic`_.
+
+System Clock
+============
+
+The SAMD21 MCU is configured to use the 32.768 kHz external oscillator
+with the on-chip PLL generating the 48 MHz system clock.
+
+Serial Port
+===========
+
+The SAMD21 MCU has 6 SERCOM based USARTs.  On the Adafruit Feather M0
+with LoRa, SERCOM0 is the Zephyr console and is available on pins 0
+(RX) and 1 (TX).
+
+I2C Port
+========
+
+The SAMD21 MCU has 6 SERCOM based USARTs.  On the Adafruit Feather M0
+with LoRa, SERCOM3 is available on pin 20 (SDA) and pin 21 (SCL).
+
+SPI Port
+========
+
+The SAMD21 MCU has 6 SERCOM based SPIs.  On the Adafruit Feather M0
+with LoRa, SERCOM4 is available on pin 22 (MISO), pin 23 (MOSI), and
+pin 24 (SCK).
+
+USB Device Port
+===============
+
+The SAMD21 MCU has a USB device port that can be used to communicate
+with a host PC.  See the :ref:`usb-samples` sample applications for
+more, such as the :ref:`usb_cdc-acm` sample which sets up a virtual
+serial port that echos characters back to the host PC.
+
+LoRa Radio
+==========
+The Semtech SX127x radio chip on the Adafruit Feather M0 with LoRa
+is attached to the SPI port (SERCOM4). Depending on the hardware
+version, 433MHz or 900MHz is supported.
+
+Programming and Debugging
+*************************
+
+The Adafruit Feather M0 with LoRa ships with a BOSSA compatible
+SAM-BA bootloader.  The bootloader can be entered by quickly tapping
+the reset button twice.
+
+Flashing
+========
+
+#. Build the Zephyr kernel and the :ref:`hello_world` sample application:
+
+   .. zephyr-app-commands::
+      :zephyr-app: samples/hello_world
+      :board: adafruit_feather_m0_lora
+      :goals: build
+      :compact:
+
+#. Connect the Adafruit Feather M0 with LoRa to your host computer
+   using USB
+
+#. Connect a 3.3 V USB to serial adapter to the board and to the
+   host.  See the `Serial Port`_ section above for the board's pin
+   connections.
+
+#. 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
+
+#. Tap the reset button twice quickly to enter bootloader mode
+
+#. Flash the image:
+
+   .. zephyr-app-commands::
+      :zephyr-app: samples/hello_world
+      :board: adafruit_feather_m0_lora
+      :goals: flash
+      :compact:
+
+   You should see "Hello World! adafruit_feather_m0_lora" in your terminal.
+
+References
+**********
+
+.. target-notes::
+
+.. _Adafruit Feather M0 with LoRa radio module Learn site:
+    https://learn.adafruit.com/adafruit-feather-m0-radio-with-lora-radio-module.
+
+.. _pinouts:
+    https://learn.adafruit.com/adafruit-feather-m0-radio-with-lora-radio-module/pinouts
+
+.. _schematic:
+    https://learn.adafruit.com/adafruit-feather-m0-radio-with-lora-radio-module/downloads

boards/arm/adafruit_feather_m0_lora/feather_connector.dtsi

@@ -0,0 +1,8 @@
+/*
+ * Copyright (c) 2020 Richard Osterloh <richard.osterloh@gmail.com>
+ * Copyright (c) 2020 Jacek Ozimek <jacek.ozmk@gmail.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+feather_i2c: &sercom3 {};

boards/arm/adafruit_feather_m0_lora/pre_dt_board.cmake

@@ -0,0 +1,7 @@
+# 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")

tests/drivers/uart/uart_async_api/testcase.yaml

@@ -2,7 +2,7 @@ common:
   platform_exclude: seeeduino_xiao serpente arduino_nano_33_iot atsamr21_xpro
     adafruit_itsybitsy_m4_express atsame54_xpro atsamd21_xpro adafruit_trinket_m0
     arduino_nano_33_iot arduino_zero atsamd21_xpro adafruit_feather_m0_basic_proto
-    arduino_mkrzero atsaml21_xpro atsamr34_xpro
+    adafruit_feather_m0_lora arduino_mkrzero atsaml21_xpro atsamr34_xpro
 
 tests:
   drivers.uart.async_api: