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//! Timer driver.
use core::cell::{Cell, RefCell};
use critical_section::CriticalSection;
use embassy_sync::blocking_mutex::Mutex;
use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
use embassy_time_driver::Driver;
use embassy_time_queue_utils::Queue;
#[cfg(feature = "rp2040")]
use pac::TIMER;
#[cfg(feature = "_rp235x")]
use pac::TIMER0 as TIMER;
use crate::interrupt::InterruptExt;
use crate::{interrupt, pac};
struct AlarmState {
timestamp: Cell<u64>,
}
unsafe impl Send for AlarmState {}
struct TimerDriver {
alarms: Mutex<CriticalSectionRawMutex, AlarmState>,
queue: Mutex<CriticalSectionRawMutex, RefCell<Queue>>,
}
embassy_time_driver::time_driver_impl!(static DRIVER: TimerDriver = TimerDriver{
alarms: Mutex::const_new(CriticalSectionRawMutex::new(), AlarmState {
timestamp: Cell::new(0),
}),
queue: Mutex::new(RefCell::new(Queue::new()))
});
impl Driver for TimerDriver {
fn now(&self) -> u64 {
loop {
let hi = TIMER.timerawh().read();
let lo = TIMER.timerawl().read();
let hi2 = TIMER.timerawh().read();
if hi == hi2 {
return (hi as u64) << 32 | (lo as u64);
}
}
}
fn schedule_wake(&self, at: u64, waker: &core::task::Waker) {
critical_section::with(|cs| {
let mut queue = self.queue.borrow(cs).borrow_mut();
if queue.schedule_wake(at, waker) {
let mut next = queue.next_expiration(self.now());
while !self.set_alarm(cs, next) {
next = queue.next_expiration(self.now());
}
}
})
}
}
impl TimerDriver {
fn set_alarm(&self, cs: CriticalSection, timestamp: u64) -> bool {
let n = 0;
let alarm = &self.alarms.borrow(cs);
alarm.timestamp.set(timestamp);
// Arm it.
// Note that we're not checking the high bits at all. This means the irq may fire early
// if the alarm is more than 72 minutes (2^32 us) in the future. This is OK, since on irq fire
// it is checked if the alarm time has passed.
TIMER.alarm(n).write_value(timestamp as u32);
let now = self.now();
if timestamp <= now {
// If alarm timestamp has passed the alarm will not fire.
// Disarm the alarm and return `false` to indicate that.
TIMER.armed().write(|w| w.set_armed(1 << n));
alarm.timestamp.set(u64::MAX);
false
} else {
true
}
}
fn check_alarm(&self) {
let n = 0;
critical_section::with(|cs| {
// clear the irq
TIMER.intr().write(|w| w.set_alarm(n, true));
let alarm = &self.alarms.borrow(cs);
let timestamp = alarm.timestamp.get();
if timestamp <= self.now() {
self.trigger_alarm(cs)
} else {
// Not elapsed, arm it again.
// This can happen if it was set more than 2^32 us in the future.
TIMER.alarm(n).write_value(timestamp as u32);
}
});
}
fn trigger_alarm(&self, cs: CriticalSection) {
let mut next = self.queue.borrow(cs).borrow_mut().next_expiration(self.now());
while !self.set_alarm(cs, next) {
next = self.queue.borrow(cs).borrow_mut().next_expiration(self.now());
}
}
}
/// safety: must be called exactly once at bootup
pub unsafe fn init() {
// init alarms
critical_section::with(|cs| {
let alarm = DRIVER.alarms.borrow(cs);
alarm.timestamp.set(u64::MAX);
});
// enable irq
TIMER.inte().write(|w| {
w.set_alarm(0, true);
});
#[cfg(feature = "rp2040")]
{
interrupt::TIMER_IRQ_0.enable();
}
#[cfg(feature = "_rp235x")]
{
interrupt::TIMER0_IRQ_0.enable();
}
}
#[cfg(all(feature = "rt", feature = "rp2040"))]
#[interrupt]
fn TIMER_IRQ_0() {
DRIVER.check_alarm()
}
#[cfg(all(feature = "rt", feature = "_rp235x"))]
#[interrupt]
fn TIMER0_IRQ_0() {
DRIVER.check_alarm()
}
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