85 lines
2.6 KiB
Rust
85 lines
2.6 KiB
Rust
use core::marker::{PhantomData, PhantomPinned};
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use core::pin::Pin;
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use core::ptr;
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use embassy::interrupt::{Interrupt, InterruptExt};
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/// # Safety
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/// When types implementing this trait are used with `Peripheral` or `PeripheralMutex`,
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/// their lifetime must not end without first calling `Drop` on the `Peripheral` or `PeripheralMutex`.
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pub unsafe trait PeripheralStateUnchecked {
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type Interrupt: Interrupt;
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fn on_interrupt(&self);
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}
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// `Peripheral` is safe because `Pin` guarantees that the memory it references will not be invalidated or reused
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// without calling `Drop`. However, it provides no guarantees about references contained within the state still being valid,
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// so this `'static` bound is necessary.
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pub trait PeripheralState: 'static {
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type Interrupt: Interrupt;
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fn on_interrupt(&self);
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}
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pub struct Peripheral<S: PeripheralStateUnchecked> {
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state: S,
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irq_setup_done: bool,
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irq: S::Interrupt,
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_not_send: PhantomData<*mut ()>,
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_pinned: PhantomPinned,
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}
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impl<S: PeripheralStateUnchecked> Peripheral<S> {
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pub fn new(irq: S::Interrupt, state: S) -> Self {
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Self {
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irq,
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irq_setup_done: false,
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state,
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_not_send: PhantomData,
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_pinned: PhantomPinned,
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}
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}
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pub fn register_interrupt(self: Pin<&mut Self>) {
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let this = unsafe { self.get_unchecked_mut() };
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if this.irq_setup_done {
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return;
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}
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this.irq.disable();
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this.irq.set_handler(|p| {
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// We need to be in a critical section so that no one can preempt us
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// and drop the state after we check whether `p.is_null()`.
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critical_section::with(|_| {
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if p.is_null() {
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// The state was dropped, so we can't operate on it.
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return;
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}
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let state = unsafe { &*(p as *const S) };
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state.on_interrupt();
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});
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});
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this.irq
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.set_handler_context((&this.state) as *const _ as *mut ());
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this.irq.enable();
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this.irq_setup_done = true;
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}
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pub fn state(self: Pin<&mut Self>) -> &S {
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&self.into_ref().get_ref().state
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}
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}
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impl<S: PeripheralStateUnchecked> Drop for Peripheral<S> {
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fn drop(&mut self) {
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self.irq.disable();
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self.irq.remove_handler();
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// Set the context to null so that the interrupt will know we're dropped
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// if we pre-empted it before it entered a critical section.
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self.irq.set_handler_context(ptr::null_mut());
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}
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}
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