i2c: implement embedded-hal-async with tests

Also adds "-Tdefmt.x" to .cargo/config.
This required for i2c async examples & on-target-tests.
Note this does not affect downstream dependents.

.cargo/config

@@ -29,6 +29,7 @@ target = "thumbv6m-none-eabi"
 rustflags = [
     "-C", "link-arg=--nmagic",
     "-C", "link-arg=-Tlink.x",
+    "-C", "link-arg=-Tdefmt.x",
     "-C", "inline-threshold=5",
     "-C", "no-vectorize-loops",
 ]

on-target-tests/Cargo.toml

@@ -32,13 +32,18 @@ harness = false
 name = "i2c_loopback"
 harness = false
 
+[[test]]
+name = "i2c_loopback_async"
+harness = false
+
 [dependencies]
 cortex-m = "0.7"
 cortex-m-rt = "0.7"
 embedded_hal_0_2 = { package = "embedded-hal", version = "0.2.5", features = [
   "unproven",
 ] }
 embedded-hal = "1.0.0"
+embedded-hal-async = "1.0.0"
 
 defmt = "0.3"
 defmt-rtt = "0.4"
@@ -59,4 +64,10 @@ heapless = { version = "0.8.0", features = [
   "portable-atomic-critical-section",
   "defmt-03",
 ] }
+# - `wfe`: we may want to signal between cores with sev
+# - `wfe` implies `cortex-m`
+nostd_async = { version = "0.6.1", features = ["wfe"] }
+futures = { version = "0.3.30", default-features = false, features = [
+  "async-await",
+] }
 itertools = { version = "0.12.0", default-features = false }

on-target-tests/tests/i2c_loopback_async.rs

@@ -0,0 +1,76 @@
+//! This test needs a connection between:
+//!
+//! | from GPIO (pico Pin) | to GPIO (pico Pin) |
+//! | -------------------- | ------------------ |
+//! |         0 (1)        |       2 (4)        |
+//! |         1 (2)        |       3 (5)        |
+
+#![no_std]
+#![no_main]
+#![cfg(test)]
+
+use defmt_rtt as _; // defmt transport
+use defmt_test as _;
+use panic_probe as _;
+use rp2040_hal as hal; // memory layout // panic handler
+
+use hal::{async_utils::AsyncPeripheral, pac::interrupt};
+
+/// The linker will place this boot block at the start of our program image. We
+/// need this to help the ROM bootloader get our code up and running.
+/// Note: This boot block is not necessary when using a rp-hal based BSP
+/// as the BSPs already perform this step.
+#[link_section = ".boot2"]
+#[used]
+pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_GENERIC_03H;
+
+/// External high-speed crystal on the Raspberry Pi Pico board is 12 MHz. Adjust
+/// if your board has a different frequency
+const XTAL_FREQ_HZ: u32 = 12_000_000u32;
+
+pub mod i2c_tests;
+
+#[interrupt]
+unsafe fn I2C0_IRQ() {
+    i2c_tests::Controller::on_interrupt();
+}
+
+#[interrupt]
+unsafe fn I2C1_IRQ() {
+    i2c_tests::Target::on_interrupt();
+}
+
+#[defmt_test::tests]
+mod tests {
+    use crate::i2c_tests::{
+        non_blocking::{self, run_test, State},
+        ADDR_10BIT, ADDR_7BIT,
+    };
+
+    #[init]
+    fn setup() -> State {
+        non_blocking::setup(super::XTAL_FREQ_HZ, ADDR_7BIT)
+    }
+
+    #[test]
+    fn embedded_hal(state: &mut State) {
+        run_test(non_blocking::embedded_hal(state, ADDR_7BIT, 2..=2));
+        run_test(non_blocking::embedded_hal(state, ADDR_10BIT, 2..=7));
+    }
+
+    #[test]
+    fn transations_iter(state: &mut State) {
+        run_test(non_blocking::transaction(state, ADDR_7BIT, 7..=9));
+        run_test(non_blocking::transaction(state, ADDR_10BIT, 7..=14));
+    }
+
+    // Sad paths:
+    // invalid tx buf on write
+    // invalid rx buf on read
+    //
+    // invalid (rx/tx) buf in transactions
+    //
+    // Peripheral Nack
+    //
+    // Arbritration conflict
+}

on-target-tests/tests/i2c_tests/mod.rs

@@ -11,6 +11,7 @@ use rp2040_hal::{
 };
 
 pub mod blocking;
+pub mod non_blocking;
 
 pub const ADDR_7BIT: u8 = 0x2c;
 pub const ADDR_10BIT: u16 = 0x12c;