time: split queue driver too, don't reexport drivers.

17 files changed, 100 insertions, 128 deletions

diff --git a/embassy-executor/Cargo.toml b/embassy-executor/Cargo.toml
index c71452398..da3c9a4fc 100644
--- a/embassy-executor/Cargo.toml
+++ b/embassy-executor/Cargo.toml
@@ -33,7 +33,8 @@ log = { version = "0.4.14", optional = true }
 rtos-trace = { version = "0.1.2", optional = true }
 
 embassy-executor-macros = { version = "0.4.0", path = "../embassy-executor-macros" }
-embassy-time = { version = "0.2", path = "../embassy-time", optional = true}
+embassy-time-driver = { version = "0.1.0", path = "../embassy-time-driver", optional = true }
+embassy-time-queue-driver = { version = "0.1.0", path = "../embassy-time-queue-driver", optional = true }
 critical-section = "1.1"
 
 document-features = "0.2.7"
@@ -63,8 +64,8 @@ nightly = ["embassy-executor-macros/nightly"]
 # See: https://github.com/embassy-rs/embassy/pull/1263
 turbowakers = []
 
-## Use timers from `embassy-time`
-integrated-timers = ["dep:embassy-time"]
+## Use the executor-integrated `embassy-time` timer queue.
+integrated-timers = ["dep:embassy-time-driver", "dep:embassy-time-queue-driver"]
 
 #! ### Architecture
 _arch = [] # some arch was picked
@@ -177,4 +178,4 @@ task-arena-size-1048576 = []
 
 # END AUTOGENERATED CONFIG FEATURES
 
-#! </details>
\ No newline at end of file
+#! </details>
diff --git a/embassy-executor/src/raw/mod.rs b/embassy-executor/src/raw/mod.rs
index b16a1c7c3..3f00be4a8 100644
--- a/embassy-executor/src/raw/mod.rs
+++ b/embassy-executor/src/raw/mod.rs
@@ -30,9 +30,7 @@ use core::ptr::NonNull;
 use core::task::{Context, Poll};
 
 #[cfg(feature = "integrated-timers")]
-use embassy_time::driver::{self, AlarmHandle};
-#[cfg(feature = "integrated-timers")]
-use embassy_time::Instant;
+use embassy_time_driver::{self, AlarmHandle};
 #[cfg(feature = "rtos-trace")]
 use rtos_trace::trace;
 
@@ -50,7 +48,7 @@ pub(crate) struct TaskHeader {
     poll_fn: SyncUnsafeCell<Option<unsafe fn(TaskRef)>>,
 
     #[cfg(feature = "integrated-timers")]
-    pub(crate) expires_at: SyncUnsafeCell<Instant>,
+    pub(crate) expires_at: SyncUnsafeCell<u64>,
     #[cfg(feature = "integrated-timers")]
     pub(crate) timer_queue_item: timer_queue::TimerQueueItem,
 }
@@ -123,7 +121,7 @@ impl<F: Future + 'static> TaskStorage<F> {
                 poll_fn: SyncUnsafeCell::new(None),
 
                 #[cfg(feature = "integrated-timers")]
-                expires_at: SyncUnsafeCell::new(Instant::from_ticks(0)),
+                expires_at: SyncUnsafeCell::new(0),
                 #[cfg(feature = "integrated-timers")]
                 timer_queue_item: timer_queue::TimerQueueItem::new(),
             },
@@ -164,7 +162,7 @@ impl<F: Future + 'static> TaskStorage<F> {
                 this.raw.state.despawn();
 
                 #[cfg(feature = "integrated-timers")]
-                this.raw.expires_at.set(Instant::MAX);
+                this.raw.expires_at.set(u64::MAX);
             }
             Poll::Pending => {}
         }
@@ -328,7 +326,7 @@ pub(crate) struct SyncExecutor {
 impl SyncExecutor {
     pub(crate) fn new(pender: Pender) -> Self {
         #[cfg(feature = "integrated-timers")]
-        let alarm = unsafe { unwrap!(driver::allocate_alarm()) };
+        let alarm = unsafe { unwrap!(embassy_time_driver::allocate_alarm()) };
 
         Self {
             run_queue: RunQueue::new(),
@@ -377,18 +375,19 @@ impl SyncExecutor {
     /// Same as [`Executor::poll`], plus you must only call this on the thread this executor was created.
     pub(crate) unsafe fn poll(&'static self) {
         #[cfg(feature = "integrated-timers")]
-        driver::set_alarm_callback(self.alarm, Self::alarm_callback, self as *const _ as *mut ());
+        embassy_time_driver::set_alarm_callback(self.alarm, Self::alarm_callback, self as *const _ as *mut ());
 
         #[allow(clippy::never_loop)]
         loop {
             #[cfg(feature = "integrated-timers")]
-            self.timer_queue.dequeue_expired(Instant::now(), wake_task_no_pend);
+            self.timer_queue
+                .dequeue_expired(embassy_time_driver::now(), wake_task_no_pend);
 
             self.run_queue.dequeue_all(|p| {
                 let task = p.header();
 
                 #[cfg(feature = "integrated-timers")]
-                task.expires_at.set(Instant::MAX);
+                task.expires_at.set(u64::MAX);
 
                 if !task.state.run_dequeue() {
                     // If task is not running, ignore it. This can happen in the following scenario:
@@ -418,7 +417,7 @@ impl SyncExecutor {
                 // If this is already in the past, set_alarm might return false
                 // In that case do another poll loop iteration.
                 let next_expiration = self.timer_queue.next_expiration();
-                if driver::set_alarm(self.alarm, next_expiration.as_ticks()) {
+                if embassy_time_driver::set_alarm(self.alarm, next_expiration) {
                     break;
                 }
             }
@@ -568,8 +567,8 @@ pub fn wake_task_no_pend(task: TaskRef) {
 struct TimerQueue;
 
 #[cfg(feature = "integrated-timers")]
-impl embassy_time::queue::TimerQueue for TimerQueue {
-    fn schedule_wake(&'static self, at: Instant, waker: &core::task::Waker) {
+impl embassy_time_queue_driver::TimerQueue for TimerQueue {
+    fn schedule_wake(&'static self, at: u64, waker: &core::task::Waker) {
         let task = waker::task_from_waker(waker);
         let task = task.header();
         unsafe {
@@ -580,7 +579,7 @@ impl embassy_time::queue::TimerQueue for TimerQueue {
 }
 
 #[cfg(feature = "integrated-timers")]
-embassy_time::timer_queue_impl!(static TIMER_QUEUE: TimerQueue = TimerQueue);
+embassy_time_queue_driver::timer_queue_impl!(static TIMER_QUEUE: TimerQueue = TimerQueue);
 
 #[cfg(feature = "rtos-trace")]
 impl rtos_trace::RtosTraceOSCallbacks for Executor {
diff --git a/embassy-executor/src/raw/timer_queue.rs b/embassy-executor/src/raw/timer_queue.rs
index 59a3b43f5..94a5f340b 100644
--- a/embassy-executor/src/raw/timer_queue.rs
+++ b/embassy-executor/src/raw/timer_queue.rs
@@ -1,7 +1,5 @@
 use core::cmp::min;
 
-use embassy_time::Instant;
-
 use super::TaskRef;
 use crate::raw::util::SyncUnsafeCell;
 
@@ -30,7 +28,7 @@ impl TimerQueue {
 
     pub(crate) unsafe fn update(&self, p: TaskRef) {
         let task = p.header();
-        if task.expires_at.get() != Instant::MAX {
+        if task.expires_at.get() != u64::MAX {
             if task.state.timer_enqueue() {
                 task.timer_queue_item.next.set(self.head.get());
                 self.head.set(Some(p));
@@ -38,18 +36,18 @@ impl TimerQueue {
         }
     }
 
-    pub(crate) unsafe fn next_expiration(&self) -> Instant {
-        let mut res = Instant::MAX;
+    pub(crate) unsafe fn next_expiration(&self) -> u64 {
+        let mut res = u64::MAX;
         self.retain(|p| {
             let task = p.header();
             let expires = task.expires_at.get();
             res = min(res, expires);
-            expires != Instant::MAX
+            expires != u64::MAX
         });
         res
     }
 
-    pub(crate) unsafe fn dequeue_expired(&self, now: Instant, on_task: impl Fn(TaskRef)) {
+    pub(crate) unsafe fn dequeue_expired(&self, now: u64, on_task: impl Fn(TaskRef)) {
         self.retain(|p| {
             let task = p.header();
             if task.expires_at.get() <= now {
diff --git a/embassy-time-driver/CHANGELOG.md b/embassy-time-driver/CHANGELOG.md
deleted file mode 100644
index d8c0c7d08..000000000
--- a/embassy-time-driver/CHANGELOG.md
+++ /dev/null
@@ -1,51 +0,0 @@
-# Changelog
-
-All notable changes to this project will be documented in this file.
-
-The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
-and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
-
-## 0.2.0 - 2023-12-04
-
-- Added tick rates in multiples of 10 kHz
-- Remove nightly and unstable-traits features in preparation for 1.75.
-- Update heapless to 0.8.
-
-## 0.1.5 - 2023-10-16
-
-- Added `links` key to Cargo.toml, to prevent multiple copies of this crate in the same binary.
-  Needed because different copies might get different tick rates, causing
-  wrong delays if the time driver is using one copy and user code is using another.
-  This is especially common when mixing crates from crates.io and git.
-
-## 0.1.4 - 2023-10-12
-
-- Added more tick rates
-
-## 0.1.3 - 2023-08-28
-
-- Update `embedded-hal-async` to `1.0.0-rc.2`
-- Update `embedded-hal v1` to `1.0.0-rc.2`
-
-## 0.1.2 - 2023-07-05
-
-- Update `embedded-hal-async` to `0.2.0-alpha.2`.
-- Update `embedded-hal v1` to `1.0.0-alpha.11`. (Note: v0.2 support is kept unchanged).
-
-## 0.1.1 - 2023-04-13
-
-- Update `embedded-hal-async` to `0.2.0-alpha.1` (uses `async fn` in traits).
-- Update `embedded-hal v1` to `1.0.0-alpha.10`. (Note: v0.2 support is kept unchanged).
-- Remove dep on `embassy-sync`.
-- Fix reentrancy issues in the `std` time driver (#1177)
-- Add `Duration::from_hz()`.
-- impl `From` conversions to/from `core::time::Duration`.
-- Add `#[must_use]` to all futures.
-- Add inherent `async fn tick()` to `Ticker`, so you can use it directly without the `Stream` trait.
-- Add more tick rates.
-- impl `Default` for `Signal`
-- Remove unnecessary uses of `atomic-polyfill`
-
-## 0.1.0 - 2022-08-26
-
-- First release
diff --git a/embassy-time-queue-driver/Cargo.toml b/embassy-time-queue-driver/Cargo.toml
new file mode 100644
index 000000000..85ee1da1b
--- /dev/null
+++ b/embassy-time-queue-driver/Cargo.toml
@@ -0,0 +1,25 @@
+[package]
+name = "embassy-time-queue-driver"
+version = "0.1.0"
+edition = "2021"
+description = "Timer queue driver trait for embassy-time"
+repository = "https://github.com/embassy-rs/embassy"
+readme = "README.md"
+license = "MIT OR Apache-2.0"
+categories = [
+    "embedded",
+    "no-std",
+    "concurrency",
+    "asynchronous",
+]
+
+# Prevent multiple copies of this crate in the same binary.
+# Needed because different copies might get different tick rates, causing
+# wrong delays if the time driver is using one copy and user code is using another.
+# This is especially common when mixing crates from crates.io and git.
+links = "embassy-time-queue"
+
+[package.metadata.embassy_docs]
+src_base = "https://github.com/embassy-rs/embassy/blob/embassy-time-queue-driver-v$VERSION/embassy-time-queue-driver/src/"
+src_base_git = "https://github.com/embassy-rs/embassy/blob/$COMMIT/embassy-time-queue-driver/src/"
+target = "x86_64-unknown-linux-gnu"
diff --git a/embassy-time-queue-driver/README.md b/embassy-time-queue-driver/README.md
new file mode 100644
index 000000000..8852b0358
--- /dev/null
+++ b/embassy-time-queue-driver/README.md
@@ -0,0 +1,8 @@
+# embassy-time-queue-driver
+
+This crate contains the driver trait used by the [`embassy-time`](https://crates.io/crates/embassy-time) timer queue.
+
+You should rarely need to use this crate directly. Only use it when implementing your own timer queue.
+
+There is two timer queue implementations, one in `embassy-time` enabled by the `generic-queue` feature, and 
+another in `embassy-executor` enabled by the `integrated-timers` feature.
diff --git a/embassy-time-queue-driver/build.rs b/embassy-time-queue-driver/build.rs
new file mode 100644
index 000000000..f328e4d9d
--- /dev/null
+++ b/embassy-time-queue-driver/build.rs
@@ -0,0 +1 @@
+fn main() {}
diff --git a/embassy-time/src/queue.rs b/embassy-time-queue-driver/src/lib.rs
index d65197c54..50736e8c7 100644
--- a/embassy-time/src/queue.rs
+++ b/embassy-time-queue-driver/src/lib.rs
@@ -1,20 +1,14 @@
-//! Timer queue implementation
-//!
-//! This module defines the interface a timer queue needs to implement to power the `embassy_time` module.
-//!
-//! # Implementing a timer queue
+#![no_std]
+#![doc = include_str!("../README.md")]
+#![warn(missing_docs)]
+
+//! ## Implementing a timer queue
 //!
 //! - Define a struct `MyTimerQueue`
 //! - Implement [`TimerQueue`] for it
 //! - Register it as the global timer queue with [`timer_queue_impl`](crate::timer_queue_impl).
 //!
-//! # Linkage details
-//!
-//! Check the documentation of the [`driver`](crate::driver) module for more information.
-//!
-//! Similarly to driver, if there is none or multiple timer queues in the crate tree, linking will fail.
-//!
-//! # Example
+//! ## Example
 //!
 //! ```
 //! use core::task::Waker;
@@ -25,23 +19,29 @@
 //! struct MyTimerQueue{}; // not public!
 //!
 //! impl TimerQueue for MyTimerQueue {
-//!     fn schedule_wake(&'static self, at: Instant, waker: &Waker) {
+//!     fn schedule_wake(&'static self, at: u64, waker: &Waker) {
 //!         todo!()
 //!     }
 //! }
-//! ```
-//! ```ignore
-//! embassy_time::timer_queue_impl!(static QUEUE: MyTimerQueue = MyTimerQueue{});
+//!
+//! embassy_time_queue_driver::timer_queue_impl!(static QUEUE: MyTimerQueue = MyTimerQueue{});
 //! ```
 use core::task::Waker;
 
-use crate::Instant;
-
 /// Timer queue
 pub trait TimerQueue {
     /// Schedules a waker in the queue to be awoken at moment `at`.
     /// If this moment is in the past, the waker might be awoken immediately.
-    fn schedule_wake(&'static self, at: Instant, waker: &Waker);
+    fn schedule_wake(&'static self, at: u64, waker: &Waker);
+}
+
+extern "Rust" {
+    fn _embassy_time_schedule_wake(at: u64, waker: &Waker);
+}
+
+/// Schedule the given waker to be woken at `at`.
+pub fn schedule_wake(at: u64, waker: &Waker) {
+    unsafe { _embassy_time_schedule_wake(at, waker) }
 }
 
 /// Set the TimerQueue implementation.
@@ -53,8 +53,8 @@ macro_rules! timer_queue_impl {
         static $name: $t = $val;
 
         #[no_mangle]
-        fn _embassy_time_schedule_wake(at: $crate::Instant, waker: &core::task::Waker) {
-            <$t as $crate::queue::TimerQueue>::schedule_wake(&$name, at, waker);
+        fn _embassy_time_schedule_wake(at: u64, waker: &core::task::Waker) {
+            <$t as $crate::TimerQueue>::schedule_wake(&$name, at, waker);
         }
     };
 }
diff --git a/embassy-time/Cargo.toml b/embassy-time/Cargo.toml
index 729a2bd4f..f27de8ab4 100644
--- a/embassy-time/Cargo.toml
+++ b/embassy-time/Cargo.toml
@@ -398,6 +398,7 @@ tick-hz-5_242_880_000 = ["embassy-time-driver/tick-hz-5_242_880_000"]
 
 [dependencies]
 embassy-time-driver = { version = "0.1.0", path = "../embassy-time-driver" }
+embassy-time-queue-driver = { version = "0.1.0", path = "../embassy-time-queue-driver" }
 
 defmt = { version = "0.3", optional = true }
 log = { version = "0.4.14", optional = true }
diff --git a/embassy-time/src/driver_mock.rs b/embassy-time/src/driver_mock.rs
index 7abc2bd70..8587f9172 100644
--- a/embassy-time/src/driver_mock.rs
+++ b/embassy-time/src/driver_mock.rs
@@ -1,8 +1,8 @@
 use core::cell::RefCell;
 
 use critical_section::Mutex as CsMutex;
+use embassy_time_driver::{AlarmHandle, Driver};
 
-use crate::driver::{AlarmHandle, Driver};
 use crate::{Duration, Instant};
 
 /// A mock driver that can be manually advanced.
@@ -28,7 +28,7 @@ use crate::{Duration, Instant};
 /// ```
 pub struct MockDriver(CsMutex<RefCell<InnerMockDriver>>);
 
-crate::driver::time_driver_impl!(static DRIVER: MockDriver = MockDriver::new());
+embassy_time_driver::time_driver_impl!(static DRIVER: MockDriver = MockDriver::new());
 
 impl MockDriver {
     /// Creates a new mock driver.
diff --git a/embassy-time/src/driver_std.rs b/embassy-time/src/driver_std.rs
index 3b5524f9e..d182f8331 100644
--- a/embassy-time/src/driver_std.rs
+++ b/embassy-time/src/driver_std.rs
@@ -6,8 +6,7 @@ use std::time::{Duration as StdDuration, Instant as StdInstant};
 use std::{mem, ptr, thread};
 
 use critical_section::Mutex as CsMutex;
-
-use crate::driver::{AlarmHandle, Driver};
+use embassy_time_driver::{AlarmHandle, Driver};
 
 const ALARM_COUNT: usize = 4;
 
@@ -45,7 +44,7 @@ struct TimeDriver {
 }
 
 const ALARM_NEW: AlarmState = AlarmState::new();
-crate::driver::time_driver_impl!(static DRIVER: TimeDriver = TimeDriver {
+embassy_time_driver::time_driver_impl!(static DRIVER: TimeDriver = TimeDriver {
     alarm_count: AtomicU8::new(0),
 
     once: Once::new(),
diff --git a/embassy-time/src/driver_wasm.rs b/embassy-time/src/driver_wasm.rs
index d75856c26..ad884f060 100644
--- a/embassy-time/src/driver_wasm.rs
+++ b/embassy-time/src/driver_wasm.rs
@@ -4,11 +4,10 @@ use std::mem::MaybeUninit;
 use std::ptr;
 use std::sync::{Mutex, Once};
 
+use embassy_time_driver::{AlarmHandle, Driver};
 use wasm_bindgen::prelude::*;
 use wasm_timer::Instant as StdInstant;
 
-use crate::driver::{AlarmHandle, Driver};
-
 const ALARM_COUNT: usize = 4;
 
 struct AlarmState {
@@ -42,7 +41,7 @@ struct TimeDriver {
 }
 
 const ALARM_NEW: AlarmState = AlarmState::new();
-crate::driver::time_driver_impl!(static DRIVER: TimeDriver = TimeDriver {
+embassy_time_driver::time_driver_impl!(static DRIVER: TimeDriver = TimeDriver {
     alarm_count: AtomicU8::new(0),
     once: Once::new(),
     alarms: UninitCell::uninit(),
diff --git a/embassy-time/src/instant.rs b/embassy-time/src/instant.rs
index 5571cdd15..909f1b173 100644
--- a/embassy-time/src/instant.rs
+++ b/embassy-time/src/instant.rs
@@ -1,7 +1,7 @@
 use core::fmt;
 use core::ops::{Add, AddAssign, Sub, SubAssign};
 
-use super::{driver, Duration, GCD_1K, GCD_1M, TICK_HZ};
+use super::{Duration, GCD_1K, GCD_1M, TICK_HZ};
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -18,7 +18,9 @@ impl Instant {
 
     /// Returns an Instant representing the current time.
     pub fn now() -> Instant {
-        Instant { ticks: driver::now() }
+        Instant {
+            ticks: embassy_time_driver::now(),
+        }
     }
 
     /// Create an Instant from a tick count since system boot.
diff --git a/embassy-time/src/lib.rs b/embassy-time/src/lib.rs
index 3f8c09f1a..d27eb92f6 100644
--- a/embassy-time/src/lib.rs
+++ b/embassy-time/src/lib.rs
@@ -10,12 +10,9 @@
 // This mod MUST go first, so that the others see its macros.
 pub(crate) mod fmt;
 
-pub use embassy_time_driver as driver;
-
 mod delay;
 mod duration;
 mod instant;
-pub mod queue;
 mod timer;
 
 #[cfg(feature = "mock-driver")]
@@ -32,8 +29,8 @@ mod driver_wasm;
 mod queue_generic;
 
 pub use delay::{block_for, Delay};
-pub use driver::TICK_HZ;
 pub use duration::Duration;
+pub use embassy_time_driver::TICK_HZ;
 pub use instant::Instant;
 pub use timer::{with_timeout, Ticker, TimeoutError, Timer};
 
diff --git a/embassy-time/src/queue_generic.rs b/embassy-time/src/queue_generic.rs
index 829368ffc..cf7a986d5 100644
--- a/embassy-time/src/queue_generic.rs
+++ b/embassy-time/src/queue_generic.rs
@@ -3,10 +3,10 @@ use core::cmp::{min, Ordering};
 use core::task::Waker;
 
 use critical_section::Mutex;
+use embassy_time_driver::{allocate_alarm, set_alarm, set_alarm_callback, AlarmHandle};
+use embassy_time_queue_driver::TimerQueue;
 use heapless::Vec;
 
-use crate::driver::{allocate_alarm, set_alarm, set_alarm_callback, AlarmHandle};
-use crate::queue::TimerQueue;
 use crate::Instant;
 
 #[cfg(feature = "generic-queue-8")]
@@ -167,12 +167,12 @@ impl Queue {
 }
 
 impl TimerQueue for Queue {
-    fn schedule_wake(&'static self, at: Instant, waker: &Waker) {
-        Queue::schedule_wake(self, at, waker);
+    fn schedule_wake(&'static self, at: u64, waker: &Waker) {
+        Queue::schedule_wake(self, Instant::from_ticks(at), waker);
     }
 }
 
-crate::timer_queue_impl!(static QUEUE: Queue = Queue::new());
+embassy_time_queue_driver::timer_queue_impl!(static QUEUE: Queue = Queue::new());
 
 #[cfg(test)]
 #[cfg(feature = "mock-driver")]
diff --git a/embassy-time/src/timer.rs b/embassy-time/src/timer.rs
index 2705ba03f..565a65cb8 100644
--- a/embassy-time/src/timer.rs
+++ b/embassy-time/src/timer.rs
@@ -1,6 +1,6 @@
 use core::future::{poll_fn, Future};
 use core::pin::Pin;
-use core::task::{Context, Poll, Waker};
+use core::task::{Context, Poll};
 
 use futures_util::future::{select, Either};
 use futures_util::stream::FusedStream;
@@ -116,7 +116,7 @@ impl Future for Timer {
         if self.yielded_once && self.expires_at <= Instant::now() {
             Poll::Ready(())
         } else {
-            schedule_wake(self.expires_at, cx.waker());
+            embassy_time_queue_driver::schedule_wake(self.expires_at.as_ticks(), cx.waker());
             self.yielded_once = true;
             Poll::Pending
         }
@@ -185,7 +185,7 @@ impl Ticker {
                 self.expires_at += dur;
                 Poll::Ready(())
             } else {
-                schedule_wake(self.expires_at, cx.waker());
+                embassy_time_queue_driver::schedule_wake(self.expires_at.as_ticks(), cx.waker());
                 Poll::Pending
             }
         })
@@ -202,7 +202,7 @@ impl Stream for Ticker {
             self.expires_at += dur;
             Poll::Ready(Some(()))
         } else {
-            schedule_wake(self.expires_at, cx.waker());
+            embassy_time_queue_driver::schedule_wake(self.expires_at.as_ticks(), cx.waker());
             Poll::Pending
         }
     }
@@ -214,11 +214,3 @@ impl FusedStream for Ticker {
         false
     }
 }
-
-extern "Rust" {
-    fn _embassy_time_schedule_wake(at: Instant, waker: &Waker);
-}
-
-fn schedule_wake(at: Instant, waker: &Waker) {
-    unsafe { _embassy_time_schedule_wake(at, waker) }
-}
diff --git a/examples/std/src/bin/serial.rs b/examples/std/src/bin/serial.rs
index 435089aad..10c85511d 100644
--- a/examples/std/src/bin/serial.rs
+++ b/examples/std/src/bin/serial.rs
@@ -3,6 +3,7 @@ mod serial_port;
 
 use async_io::Async;
 use embassy_executor::Executor;
+use embassy_time as _;
 use embedded_io_async::Read;
 use log::*;
 use nix::sys::termios;