boards: Added support for the Raspberry Pi Pico board

Added support for Raspberry Pi's Pico board, using
the RP2040 SoC.

Signed-off-by: Yonatan Schachter <yonatan.schachter@gmail.com>

CODEOWNERS

@@ -130,6 +130,7 @@
 /boards/arm/quick_feather/                @kowalewskijan @kgugala
 /boards/arm/rak4631_nrf52840/             @gpaquet85
 /boards/arm/rak5010_nrf52840/             @gpaquet85
+/boards/arm/rpi_pico/                     @yonsch
 /boards/arm/ronoth_lodev/                 @NorthernDean
 /boards/arm/xmc45_relax_kit/              @parthitce
 /boards/arm/sam4e_xpro/                   @nandojve

boards/arm/rpi_pico/Kconfig.board

@@ -0,0 +1,6 @@
+# Copyright (c) 2021 Yonatan Schachter
+# SPDX-License-Identifier: Apache-2.0
+
+config BOARD_RPI_PICO
+	bool "Raspberry Pi Pico Board"
+	depends on SOC_RP2040

boards/arm/rpi_pico/Kconfig.defconfig

@@ -0,0 +1,12 @@
+# Copyright (c) 2021 Yonatan Schachter
+# SPDX-License-Identifier: Apache-2.0
+
+if BOARD_RPI_PICO
+
+config BOARD
+	default "rpi_pico"
+
+config RP2_FLASH_W25Q080
+	default y
+
+endif # BOARD_RPI_PICO

boards/arm/rpi_pico/doc/index.rst

@@ -0,0 +1,110 @@
+.. _rpi_pico:
+
+Raspberry Pi Pico
+#################
+
+Overview
+********
+
+The Raspberry Pi Pico is a small, low-cost, versatile board from
+Raspberry Pi. It is equipped with an RP2040 SoC, an on-board LED,
+a USB connector, and an SWD interface. The USB bootloader allows it
+to be flashed without any adapter, in a drag-and-drop manner.
+It is also possible to flash and debug the Pico with its SWD interface,
+using an external adapter.
+
+Hardware
+********
+- Dual core Arm Cortex-M0+ processor running up to 133MHz
+- 264KB on-chip SRAM
+- 2MB on-board QSPI flash with XIP capabilities
+- 26 GPIO pins
+- 3 Analog inputs
+- 2 UART peripherals
+- 2 SPI controllers
+- 2 I2C controllers
+- 16 PWM channels
+- USB 1.1 controller (host/device)
+- 8 Programmable I/O (PIO) for custom peripherals
+- On-board LED
+
+
+.. figure:: img/rpi_pico.png
+     :width: 150px
+     :align: center
+     :alt: Raspberry Pi Pico
+
+     Raspberry Pi Pico (Image courtesy of Raspberry Pi)
+
+Supported Features
+==================
+
+The rpi_pico board configuration supports the following
+hardware features:
+
+.. list-table::
+   :header-rows: 1
+
+   * - Peripheral
+     - Kconfig option
+     - Devicetree compatible
+   * - NVIC
+     - N/A
+     - :dtcompatible:`arm,v6m-nvic`
+   * - UART
+     - :kconfig:`CONFIG_SERIAL`
+     - :dtcompatible:`rpi,pico-uart`
+   * - GPIO
+     - :kconfig:`CONFIG_GPIO`
+     - :dtcompatible:`rpi,pico-gpio`
+
+Programming and Debugging
+*************************
+
+Flashing
+========
+
+Using an SWD adapter
+--------------------
+
+The Raspberry Pi Pico has an SWD interface that can be used to program
+and debug the on board RP2040. This interface can be utilized by openocd.
+However, to use it with the RP2040, a custom fork of openocd is needed.
+This fork can be found here: https://github.com/raspberrypi/openocd
+
+Depending on the interface used (such as JLink), you might need to
+checkout to a branch that supports this interface, before proceeding.
+Build and install openocd as described in the README.
+
+When openocd is installed, you can flash the board with the following
+command (assuming JLink is used):
+
+.. code-block:: console
+
+   $ openocd -f interface/jlink.cfg -c 'transport select swd' -f target/rp2040.cfg -c "adapter speed 2000" -c 'targets rp2040.core0' -c 'program path/to/zephyr.elf verify reset exit'
+
+Debugging
+=========
+
+The SWD interface can also be used to debug the board. To achieve this,
+install openocd as described for flashing the board. Also, install gdb-multiarch.
+Then run the following command:
+
+.. code-block:: console
+
+   $ openocd -f interface/jlink.cfg -c 'transport select swd' -f target/rp2040.cfg -c "adapter speed 2000" -c 'targets rp2040.core0'
+
+On another terminal, run:
+
+.. code-block:: console
+
+   $ gdb-multiarch
+
+Inside gdb, run:
+
+.. code-block:: console
+
+   (gdb) tar ext :3333
+   (gdb) file path/to/zephyr.elf
+
+You can then start debugging the board.

boards/arm/rpi_pico/rpi_pico-pinctrl.dtsi

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2021, Yonatan Schachter
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <dt-bindings/pinctrl/rpi-pico-rp2040-pinctrl.h>
+
+&pinctrl {
+	uart0_default: uart0_default {
+		group1 {
+			pinmux = <UART0_TX_P0>;
+		};
+		group2 {
+			pinmux = <UART0_RX_P1>;
+			input-enable;
+		};
+	};
+};

boards/arm/rpi_pico/rpi_pico.dts

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2021 Yonatan Schachter
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/dts-v1/;
+
+#include <rpi_pico/rp2040.dtsi>
+#include "rpi_pico-pinctrl.dtsi"
+
+/ {
+	chosen {
+		zephyr,sram = &sram0;
+		zephyr,flash = &flash0;
+		zephyr,console = &uart0;
+		zephyr,code-partition = &code_partition;
+	};
+
+	leds {
+		compatible = "gpio-leds";
+		led0: led_0 {
+			gpios = <&gpio0 25 GPIO_ACTIVE_LOW>;
+			label = "LED";
+		};
+	};
+
+	aliases {
+		led0 = &led0;
+	};
+};
+
+&flash0 {
+	reg = <0x10000000 DT_SIZE_M(2)>;
+
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		/* Reserved memory for the second stage bootloader */
+		second_stage_bootloader: partition@0 {
+			label = "second_stage_bootloader";
+			reg = <0x00000000 0x100>;
+			read-only;
+		};
+
+		/*
+		 * Usable flash. Starts at 0x100, after the bootloader. The partition
+		 * size is 2MB minus the 0x100 bytes taken by the bootloader.
+		 */
+		code_partition: partition@100 {
+			label = "code-partition";
+			reg = <0x100 (DT_SIZE_M(2) - 0x100)>;
+			read-only;
+		};
+	};
+};
+
+&uart0 {
+	current-speed = <115200>;
+	status = "okay";
+	pinctrl-0 = <&uart0_default>;
+	pinctrl-names = "default";
+};
+
+&gpio0 {
+	status = "okay";
+};

boards/arm/rpi_pico/rpi_pico.yaml

@@ -0,0 +1,13 @@
+identifier: rpi_pico
+name: RaspberryPi-Pico
+type: mcu
+arch: arm
+flash: 2048
+ram: 264
+toolchain:
+  - zephyr
+  - gnuarmemb
+  - xtools
+supported:
+  - uart
+  - gpio

boards/arm/rpi_pico/rpi_pico_defconfig

@@ -0,0 +1,8 @@
+CONFIG_SOC_SERIES_RP2XXX=y
+CONFIG_SOC_RP2040=y
+CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC=125000000
+CONFIG_SERIAL=y
+CONFIG_CONSOLE=y
+CONFIG_UART_CONSOLE=y
+CONFIG_GPIO=y
+CONFIG_USE_DT_CODE_PARTITION=y