Add embedded_hal_async support for embassy-rp

This commit adds support for embedded-hal-async to the Embassy
Raspberry PI crate.

tests/rp/src/bin/gpio_async.rs

@@ -0,0 +1,148 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::{assert, *};
+use embassy::executor::Spawner;
+use embassy::time::{Duration, Instant, Timer};
+use embassy_rp::gpio::{Input, Level, Output, Pull};
+use embassy_rp::Peripherals;
+use futures::future::join;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy::main]
+async fn main(_spawner: Spawner, p: Peripherals) {
+    info!("embassy-rp gpio_async test");
+
+    // On the CI device the following pins are connected with each other.
+    let (mut output_pin, mut input_pin) = (p.PIN_0, p.PIN_1);
+
+    {
+        info!("test wait_for_high");
+        let mut output = Output::new(&mut output_pin, Level::Low);
+        let mut input = Input::new(&mut input_pin, Pull::None);
+
+        assert!(input.is_low(), "input was expected to be low");
+
+        let set_high_future = async {
+            // Allow time for wait_for_high_future to await wait_for_high().
+            Timer::after(Duration::from_millis(10)).await;
+            output.set_high();
+        };
+        let wait_for_high_future = async {
+            let start = Instant::now();
+            input.wait_for_high().await;
+            assert_duration(start);
+        };
+        join(set_high_future, wait_for_high_future).await;
+        info!("test wait_for_high: OK\n");
+    }
+
+    {
+        info!("test wait_for_low");
+        let mut output = Output::new(&mut output_pin, Level::High);
+        let mut input = Input::new(&mut input_pin, Pull::None);
+
+        assert!(input.is_high(), "input was expected to be high");
+
+        let set_low_future = async {
+            Timer::after(Duration::from_millis(10)).await;
+            output.set_low();
+        };
+        let wait_for_low_future = async {
+            let start = Instant::now();
+            input.wait_for_low().await;
+            assert_duration(start);
+        };
+        join(set_low_future, wait_for_low_future).await;
+        info!("test wait_for_low: OK\n");
+    }
+
+    {
+        info!("test wait_for_rising_edge");
+        let mut output = Output::new(&mut output_pin, Level::Low);
+        let mut input = Input::new(&mut input_pin, Pull::None);
+
+        assert!(input.is_low(), "input was expected to be low");
+
+        let set_high_future = async {
+            Timer::after(Duration::from_millis(10)).await;
+            output.set_high();
+        };
+        let wait_for_rising_edge_future = async {
+            let start = Instant::now();
+            input.wait_for_rising_edge().await;
+            assert_duration(start);
+        };
+        join(set_high_future, wait_for_rising_edge_future).await;
+        info!("test wait_for_rising_edge: OK\n");
+    }
+
+    {
+        info!("test wait_for_falling_edge");
+        let mut output = Output::new(&mut output_pin, Level::High);
+        let mut input = Input::new(&mut input_pin, Pull::None);
+
+        assert!(input.is_high(), "input was expected to be high");
+
+        let set_low_future = async {
+            Timer::after(Duration::from_millis(10)).await;
+            output.set_low();
+        };
+        let wait_for_falling_edge_future = async {
+            let start = Instant::now();
+            input.wait_for_falling_edge().await;
+            assert_duration(start);
+        };
+        join(set_low_future, wait_for_falling_edge_future).await;
+        info!("test wait_for_falling_edge: OK\n");
+    }
+
+    {
+        info!("test wait_for_any_edge (falling)");
+        let mut output = Output::new(&mut output_pin, Level::High);
+        let mut input = Input::new(&mut input_pin, Pull::None);
+
+        assert!(input.is_high(), "input was expected to be high");
+
+        let set_low_future = async {
+            Timer::after(Duration::from_millis(10)).await;
+            output.set_low();
+        };
+        let wait_for_any_edge_future = async {
+            let start = Instant::now();
+            input.wait_for_any_edge().await;
+            assert_duration(start);
+        };
+        join(set_low_future, wait_for_any_edge_future).await;
+        info!("test wait_for_any_edge (falling): OK\n");
+    }
+
+    {
+        info!("test wait_for_any_edge (rising)");
+        let mut output = Output::new(&mut output_pin, Level::Low);
+        let mut input = Input::new(&mut input_pin, Pull::None);
+
+        assert!(input.is_low(), "input was expected to be low");
+
+        let set_high_future = async {
+            Timer::after(Duration::from_millis(10)).await;
+            output.set_high();
+        };
+        let wait_for_any_edge_future = async {
+            let start = Instant::now();
+            input.wait_for_any_edge().await;
+            assert_duration(start);
+        };
+        join(set_high_future, wait_for_any_edge_future).await;
+        info!("test wait_for_any_edge (rising): OK\n");
+    }
+
+    info!("Test OK");
+    cortex_m::asm::bkpt();
+
+    fn assert_duration(start: Instant) {
+        let dur = Instant::now() - start;
+        assert!(dur >= Duration::from_millis(10) && dur < Duration::from_millis(11));
+    }
+}