add avr support

embassy-executor-macros/src/lib.rs

@@ -62,6 +62,13 @@ pub fn task(args: TokenStream, item: TokenStream) -> TokenStream {
     task::run(&args.meta, f).unwrap_or_else(|x| x).into()
 }
 
+#[proc_macro_attribute]
+pub fn main_avr(args: TokenStream, item: TokenStream) -> TokenStream {
+    let args = syn::parse_macro_input!(args as Args);
+    let f = syn::parse_macro_input!(item as syn::ItemFn);
+    main::run(&args.meta, f, main::avr()).unwrap_or_else(|x| x).into()
+}
+
 /// Creates a new `executor` instance and declares an application entry point for Cortex-M spawning the corresponding function body as an async task.
 ///
 /// The following restrictions apply:

embassy-executor-macros/src/macros/main.rs

@@ -12,6 +12,20 @@ struct Args {
     entry: Option<String>,
 }
 
+pub fn avr() -> TokenStream {
+    quote! {
+        #[avr_device::entry]
+        fn main() -> ! {
+            let mut executor = ::embassy_executor::Executor::new();
+            let executor = unsafe { __make_static(&mut executor) };
+
+            executor.run(|spawner| {
+                spawner.must_spawn(__embassy_main(spawner));
+            })
+        }
+    }
+}
+
 pub fn riscv(args: &[NestedMeta]) -> TokenStream {
     let maybe_entry = match Args::from_list(args) {
         Ok(args) => args.entry,

embassy-executor/Cargo.toml

@@ -55,6 +55,7 @@ critical-section = { version = "1.1", features = ["std"] }
 
 # Architecture
 _arch = [] # some arch was picked
+arch-avr = ["_arch", "dep:portable-atomic"]
 arch-std = ["_arch", "critical-section/std"]
 arch-cortex-m = ["_arch", "dep:cortex-m"]
 arch-riscv32 = ["_arch", "dep:portable-atomic"]

embassy-executor/src/arch/avr.rs

@@ -0,0 +1,60 @@
+#[cfg(feature = "executor-interrupt")]
+compile_error!("`executor-interrupt` is not supported with `arch-avr`.");
+
+#[cfg(feature = "executor-thread")]
+pub use thread::*;
+#[cfg(feature = "executor-thread")]
+mod thread {
+    use core::marker::PhantomData;
+
+    pub use embassy_executor_macros::main_avr as main;
+
+    use crate::{raw, Spawner};
+
+    #[export_name = "__pender"]
+    fn __pender(_context: *mut ()) {}
+
+    /// avr Executor
+    pub struct Executor {
+        inner: raw::Executor,
+        not_send: PhantomData<*mut ()>,
+    }
+
+    impl Executor {
+        /// Create a new Executor.
+        pub fn new() -> Self {
+            Self {
+                inner: raw::Executor::new(core::ptr::null_mut()),
+                not_send: PhantomData,
+            }
+        }
+
+        /// Run the executor.
+        ///
+        /// The `init` closure is called with a [`Spawner`] that spawns tasks on
+        /// this executor. Use it to spawn the initial task(s). After `init` returns,
+        /// the executor starts running the tasks.
+        ///
+        /// To spawn more tasks later, you may keep copies of the [`Spawner`] (it is `Copy`),
+        /// for example by passing it as an argument to the initial tasks.
+        ///
+        /// This function requires `&'static mut self`. This means you have to store the
+        /// Executor instance in a place where it'll live forever and grants you mutable
+        /// access. There's a few ways to do this:
+        ///
+        /// - a [StaticCell](https://docs.rs/static_cell/latest/static_cell/) (safe)
+        /// - a `static mut` (unsafe)
+        /// - a local variable in a function you know never returns (like `fn main() -> !`), upgrading its lifetime with `transmute`. (unsafe)
+        ///
+        /// This function never returns.
+        pub fn run(&'static mut self, init: impl FnOnce(Spawner)) -> ! {
+            init(self.inner.spawner());
+
+            loop {
+                unsafe {
+                    self.inner.poll();
+                }
+            }
+        }
+    }
+}

embassy-executor/src/lib.rs

@@ -20,9 +20,10 @@ macro_rules! check_at_most_one {
         check_at_most_one!(@amo [$($f)*] [$($f)*] []);
     };
 }
-check_at_most_one!("arch-cortex-m", "arch-riscv32", "arch-std", "arch-wasm",);
+check_at_most_one!("arch-avr", "arch-cortex-m", "arch-riscv32", "arch-std", "arch-wasm",);
 
 #[cfg(feature = "_arch")]
+#[cfg_attr(feature = "arch-avr", path = "arch/avr.rs")]
 #[cfg_attr(feature = "arch-cortex-m", path = "arch/cortex_m.rs")]
 #[cfg_attr(feature = "arch-riscv32", path = "arch/riscv32.rs")]
 #[cfg_attr(feature = "arch-std", path = "arch/std.rs")]