Create blinky application

Blinky is a rust port of the samples/blinky application from the main
zephyr repo.  It performs the same function, but using the DT and GPIO
abstractions provided in the zephyr::sys module.

Signed-off-by: David Brown <[email protected]>

Author: d3zd3z

samples/blinky/CMakeLists.txt

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+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(blinky)
+
+rust_cargo_application()

samples/blinky/Cargo.toml

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+# Copyright (c) 2024 Linaro LTD
+# SPDX-License-Identifier: Apache-2.0
+
+[package]
+# This must be rustapp for now.
+name = "rustapp"
+version = "0.1.0"
+edition = "2021"
+description = "A sample hello world application in Rust"
+license = "Apache-2.0 or MIT"
+
+[lib]
+crate-type = ["staticlib"]
+
+[dependencies]
+zephyr = "3.7.0"
+log = "0.4.22"

samples/blinky/README.rst

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+.. zephyr:code-sample:: blinky
+   :name: Blinky
+   :relevant-api: gpio_interface
+
+   Blink an LED forever using the GPIO API.
+
+Overview
+********
+
+The Blinky sample blinks an LED forever using the :ref:`GPIO API <gpio_api>`.
+
+The source code shows how to:
+
+#. Get a pin specification from the :ref:`devicetree <dt-guide>` as a
+   :c:struct:`gpio_dt_spec`
+#. Configure the GPIO pin as an output
+#. Toggle the pin forever
+
+See :zephyr:code-sample:`pwm-blinky` for a similar sample that uses the PWM API instead.
+
+.. _blinky-sample-requirements:
+
+Requirements
+************
+
+Your board must:
+
+#. Have an LED connected via a GPIO pin (these are called "User LEDs" on many of
+   Zephyr's :ref:`boards`).
+#. Have the LED configured using the ``led0`` devicetree alias.
+
+Building and Running
+********************
+
+Build and flash Blinky as follows, changing ``reel_board`` for your board:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/basic/blinky
+   :board: reel_board
+   :goals: build flash
+   :compact:
+
+After flashing, the LED starts to blink and messages with the current LED state
+are printed on the console. If a runtime error occurs, the sample exits without
+printing to the console.
+
+Build errors
+************
+
+You will see a build error at the source code line defining the ``struct
+gpio_dt_spec led`` variable if you try to build Blinky for an unsupported
+board.
+
+On GCC-based toolchains, the error looks like this:
+
+.. code-block:: none
+
+   error: '__device_dts_ord_DT_N_ALIAS_led_P_gpios_IDX_0_PH_ORD' undeclared here (not in a function)
+
+Adding board support
+********************
+
+To add support for your board, add something like this to your devicetree:
+
+.. code-block:: DTS
+
+   / {
+   	aliases {
+   		led0 = &myled0;
+   	};
+
+   	leds {
+   		compatible = "gpio-leds";
+   		myled0: led_0 {
+   			gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
+                };
+   	};
+   };
+
+The above sets your board's ``led0`` alias to use pin 13 on GPIO controller
+``gpio0``. The pin flags :c:macro:`GPIO_ACTIVE_HIGH` mean the LED is on when
+the pin is set to its high state, and off when the pin is in its low state.
+
+Tips:
+
+- See :dtcompatible:`gpio-leds` for more information on defining GPIO-based LEDs
+  in devicetree.
+
+- If you're not sure what to do, check the devicetrees for supported boards which
+  use the same SoC as your target. See :ref:`get-devicetree-outputs` for details.
+
+- See :zephyr_file:`include/zephyr/dt-bindings/gpio/gpio.h` for the flags you can use
+  in devicetree.
+
+- If the LED is built in to your board hardware, the alias should be defined in
+  your :ref:`BOARD.dts file <devicetree-in-out-files>`. Otherwise, you can
+  define one in a :ref:`devicetree overlay <set-devicetree-overlays>`.

samples/blinky/prj.conf

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+CONFIG_GPIO=y
+
+CONFIG_RUST=y
+CONFIG_RUST_ALLOC=y
+
+CONFIG_DEBUG=y
+CONFIG_MAIN_STACK_SIZE=8192
+
+# Verify that userspace builds work.
+# CONFIG_USERSPACE=y

samples/blinky/sample.yaml

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+sample:
+  name: Blinky Sample
+tests:
+  sample.basic.blinky:
+    tags:
+      - LED
+      - gpio
+    filter: dt_enabled_alias_with_parent_compat("led0", "gpio-leds")
+    depends_on: gpio
+    harness: led
+    integration_platforms:
+      - frdm_k64f

samples/blinky/src/lib.rs

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+// Copyright (c) 2024 Linaro LTD
+// SPDX-License-Identifier: Apache-2.0
+
+#![no_std]
+
+use log::warn;
+
+use core::ffi::c_void;
+
+use zephyr::raw::GPIO_OUTPUT_ACTIVE;
+use zephyr::time::{ Duration, sleep };
+
+#[no_mangle]
+extern "C" fn rust_main() {
+    zephyr::set_logger();
+
+    warn!("Starting blinky");
+    // println!("Blinky!");
+    // Invoke "blink" as a user thread.
+    // blink();
+    if false {
+        unsafe {
+            zephyr::raw::k_thread_user_mode_enter
+                (Some(blink),
+                core::ptr::null_mut(),
+                core::ptr::null_mut(),
+                core::ptr::null_mut());
+        }
+    } else {
+        unsafe {
+            blink(core::ptr::null_mut(),
+                  core::ptr::null_mut(),
+                  core::ptr::null_mut());
+        }
+    }
+}
+
+// fn blink() {
+unsafe extern "C" fn blink(_p1: *mut c_void, _p2: *mut c_void, _p3: *mut c_void) {
+    warn!("Inside of blinky");
+
+    let mut led0 = zephyr::devicetree::aliases::led0::get_instance();
+
+    if !led0.is_ready() {
+        warn!("LED is not ready");
+        loop {
+        }
+        // return;
+    }
+
+    led0.configure(GPIO_OUTPUT_ACTIVE);
+    let duration = Duration::millis_at_least(500);
+    loop {
+        led0.toggle_pin();
+        sleep(duration);
+    }
+}

samples/blinky/src/main.c

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+/*
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+#include <zephyr/kernel.h>
+#include <zephyr/drivers/gpio.h>
+
+/* 1000 msec = 1 sec */
+#define SLEEP_TIME_MS   1000
+
+/* The devicetree node identifier for the "led0" alias. */
+#define LED0_NODE DT_ALIAS(led0)
+
+/*
+ * A build error on this line means your board is unsupported.
+ * See the sample documentation for information on how to fix this.
+ */
+static const struct gpio_dt_spec led = GPIO_DT_SPEC_GET(LED0_NODE, gpios);
+
+int main(void)
+{
+	int ret;
+	bool led_state = true;
+
+	if (!gpio_is_ready_dt(&led)) {
+		return 0;
+	}
+
+	ret = gpio_pin_configure_dt(&led, GPIO_OUTPUT_ACTIVE);
+	if (ret < 0) {
+		return 0;
+	}
+
+	while (1) {
+		ret = gpio_pin_toggle_dt(&led);
+		if (ret < 0) {
+			return 0;
+		}
+
+		led_state = !led_state;
+		printf("LED state: %s\n", led_state ? "ON" : "OFF");
+		k_msleep(SLEEP_TIME_MS);
+	}
+	return 0;
+}