--- /dev/null
-use crate::{init::PinInit, prelude::*, time::Ktime, types::Opaque};
+ // SPDX-License-Identifier: GPL-2.0
+
+ //! Intrusive high resolution timers.
+ //!
+ //! Allows running timer callbacks without doing allocations at the time of
+ //! starting the timer. For now, only one timer per type is allowed.
+ //!
+ //! # Vocabulary
+ //!
+ //! States:
+ //!
+ //! - Stopped: initialized but not started, or cancelled, or not restarted.
+ //! - Started: initialized and started or restarted.
+ //! - Running: executing the callback.
+ //!
+ //! Operations:
+ //!
+ //! * Start
+ //! * Cancel
+ //! * Restart
+ //!
+ //! Events:
+ //!
+ //! * Expire
+ //!
+ //! ## State Diagram
+ //!
+ //! ```text
+ //! Return NoRestart
+ //! +---------------------------------------------------------------------+
+ //! | |
+ //! | |
+ //! | |
+ //! | Return Restart |
+ //! | +------------------------+ |
+ //! | | | |
+ //! | | | |
+ //! v v | |
+ //! +-----------------+ Start +------------------+ +--------+-----+--+
+ //! | +---------------->| | | |
+ //! Init | | | | Expire | |
+ //! --------->| Stopped | | Started +---------->| Running |
+ //! | | Cancel | | | |
+ //! | |<----------------+ | | |
+ //! +-----------------+ +---------------+--+ +-----------------+
+ //! ^ |
+ //! | |
+ //! +---------+
+ //! Restart
+ //! ```
+ //!
+ //!
+ //! A timer is initialized in the **stopped** state. A stopped timer can be
+ //! **started** by the `start` operation, with an **expiry** time. After the
+ //! `start` operation, the timer is in the **started** state. When the timer
+ //! **expires**, the timer enters the **running** state and the handler is
+ //! executed. After the handler has returned, the timer may enter the
+ //! **started* or **stopped** state, depending on the return value of the
+ //! handler. A timer in the **started** or **running** state may be **canceled**
+ //! by the `cancel` operation. A timer that is cancelled enters the **stopped**
+ //! state.
+ //!
+ //! A `cancel` or `restart` operation on a timer in the **running** state takes
+ //! effect after the handler has returned and the timer has transitioned
+ //! out of the **running** state.
+ //!
+ //! A `restart` operation on a timer in the **stopped** state is equivalent to a
+ //! `start` operation.
+
+ use super::ClockId;
++use crate::{prelude::*, time::Ktime, types::Opaque};
+ use core::marker::PhantomData;
++use pin_init::PinInit;
+
+ /// A timer backed by a C `struct hrtimer`.
+ ///
+ /// # Invariants
+ ///
+ /// * `self.timer` is initialized by `bindings::hrtimer_setup`.
+ #[pin_data]
+ #[repr(C)]
+ pub struct HrTimer<T> {
+ #[pin]
+ timer: Opaque<bindings::hrtimer>,
+ mode: HrTimerMode,
+ _t: PhantomData<T>,
+ }
+
+ // SAFETY: Ownership of an `HrTimer` can be moved to other threads and
+ // used/dropped from there.
+ unsafe impl<T> Send for HrTimer<T> {}
+
+ // SAFETY: Timer operations are locked on the C side, so it is safe to operate
+ // on a timer from multiple threads.
+ unsafe impl<T> Sync for HrTimer<T> {}
+
+ impl<T> HrTimer<T> {
+ /// Return an initializer for a new timer instance.
+ pub fn new(mode: HrTimerMode, clock: ClockId) -> impl PinInit<Self>
+ where
+ T: HrTimerCallback,
+ {
+ pin_init!(Self {
+ // INVARIANT: We initialize `timer` with `hrtimer_setup` below.
+ timer <- Opaque::ffi_init(move |place: *mut bindings::hrtimer| {
+ // SAFETY: By design of `pin_init!`, `place` is a pointer to a
+ // live allocation. hrtimer_setup will initialize `place` and
+ // does not require `place` to be initialized prior to the call.
+ unsafe {
+ bindings::hrtimer_setup(
+ place,
+ Some(T::Pointer::run),
+ clock.into_c(),
+ mode.into_c(),
+ );
+ }
+ }),
+ mode: mode,
+ _t: PhantomData,
+ })
+ }
+
+ /// Get a pointer to the contained `bindings::hrtimer`.
+ ///
+ /// This function is useful to get access to the value without creating
+ /// intermediate references.
+ ///
+ /// # Safety
+ ///
+ /// `this` must point to a live allocation of at least the size of `Self`.
+ unsafe fn raw_get(this: *const Self) -> *mut bindings::hrtimer {
+ // SAFETY: The field projection to `timer` does not go out of bounds,
+ // because the caller of this function promises that `this` points to an
+ // allocation of at least the size of `Self`.
+ unsafe { Opaque::raw_get(core::ptr::addr_of!((*this).timer)) }
+ }
+
+ /// Cancel an initialized and potentially running timer.
+ ///
+ /// If the timer handler is running, this function will block until the
+ /// handler returns.
+ ///
+ /// Note that the timer might be started by a concurrent start operation. If
+ /// so, the timer might not be in the **stopped** state when this function
+ /// returns.
+ ///
+ /// Users of the `HrTimer` API would not usually call this method directly.
+ /// Instead they would use the safe [`HrTimerHandle::cancel`] on the handle
+ /// returned when the timer was started.
+ ///
+ /// This function is useful to get access to the value without creating
+ /// intermediate references.
+ ///
+ /// # Safety
+ ///
+ /// `this` must point to a valid `Self`.
+ pub(crate) unsafe fn raw_cancel(this: *const Self) -> bool {
+ // SAFETY: `this` points to an allocation of at least `HrTimer` size.
+ let c_timer_ptr = unsafe { HrTimer::raw_get(this) };
+
+ // If the handler is running, this will wait for the handler to return
+ // before returning.
+ // SAFETY: `c_timer_ptr` is initialized and valid. Synchronization is
+ // handled on the C side.
+ unsafe { bindings::hrtimer_cancel(c_timer_ptr) != 0 }
+ }
+ }
+
+ /// Implemented by pointer types that point to structs that contain a [`HrTimer`].
+ ///
+ /// `Self` must be [`Sync`] because it is passed to timer callbacks in another
+ /// thread of execution (hard or soft interrupt context).
+ ///
+ /// Starting a timer returns a [`HrTimerHandle`] that can be used to manipulate
+ /// the timer. Note that it is OK to call the start function repeatedly, and
+ /// that more than one [`HrTimerHandle`] associated with a [`HrTimerPointer`] may
+ /// exist. A timer can be manipulated through any of the handles, and a handle
+ /// may represent a cancelled timer.
+ pub trait HrTimerPointer: Sync + Sized {
+ /// A handle representing a started or restarted timer.
+ ///
+ /// If the timer is running or if the timer callback is executing when the
+ /// handle is dropped, the drop method of [`HrTimerHandle`] should not return
+ /// until the timer is stopped and the callback has completed.
+ ///
+ /// Note: When implementing this trait, consider that it is not unsafe to
+ /// leak the handle.
+ type TimerHandle: HrTimerHandle;
+
+ /// Start the timer with expiry after `expires` time units. If the timer was
+ /// already running, it is restarted with the new expiry time.
+ fn start(self, expires: Ktime) -> Self::TimerHandle;
+ }
+
+ /// Unsafe version of [`HrTimerPointer`] for situations where leaking the
+ /// [`HrTimerHandle`] returned by `start` would be unsound. This is the case for
+ /// stack allocated timers.
+ ///
+ /// Typical implementers are pinned references such as [`Pin<&T>`].
+ ///
+ /// # Safety
+ ///
+ /// Implementers of this trait must ensure that instances of types implementing
+ /// [`UnsafeHrTimerPointer`] outlives any associated [`HrTimerPointer::TimerHandle`]
+ /// instances.
+ pub unsafe trait UnsafeHrTimerPointer: Sync + Sized {
+ /// A handle representing a running timer.
+ ///
+ /// # Safety
+ ///
+ /// If the timer is running, or if the timer callback is executing when the
+ /// handle is dropped, the drop method of [`Self::TimerHandle`] must not return
+ /// until the timer is stopped and the callback has completed.
+ type TimerHandle: HrTimerHandle;
+
+ /// Start the timer after `expires` time units. If the timer was already
+ /// running, it is restarted at the new expiry time.
+ ///
+ /// # Safety
+ ///
+ /// Caller promises keep the timer structure alive until the timer is dead.
+ /// Caller can ensure this by not leaking the returned [`Self::TimerHandle`].
+ unsafe fn start(self, expires: Ktime) -> Self::TimerHandle;
+ }
+
+ /// A trait for stack allocated timers.
+ ///
+ /// # Safety
+ ///
+ /// Implementers must ensure that `start_scoped` does not return until the
+ /// timer is dead and the timer handler is not running.
+ pub unsafe trait ScopedHrTimerPointer {
+ /// Start the timer to run after `expires` time units and immediately
+ /// after call `f`. When `f` returns, the timer is cancelled.
+ fn start_scoped<T, F>(self, expires: Ktime, f: F) -> T
+ where
+ F: FnOnce() -> T;
+ }
+
+ // SAFETY: By the safety requirement of [`UnsafeHrTimerPointer`], dropping the
+ // handle returned by [`UnsafeHrTimerPointer::start`] ensures that the timer is
+ // killed.
+ unsafe impl<T> ScopedHrTimerPointer for T
+ where
+ T: UnsafeHrTimerPointer,
+ {
+ fn start_scoped<U, F>(self, expires: Ktime, f: F) -> U
+ where
+ F: FnOnce() -> U,
+ {
+ // SAFETY: We drop the timer handle below before returning.
+ let handle = unsafe { UnsafeHrTimerPointer::start(self, expires) };
+ let t = f();
+ drop(handle);
+ t
+ }
+ }
+
+ /// Implemented by [`HrTimerPointer`] implementers to give the C timer callback a
+ /// function to call.
+ // This is split from `HrTimerPointer` to make it easier to specify trait bounds.
+ pub trait RawHrTimerCallback {
+ /// Type of the parameter passed to [`HrTimerCallback::run`]. It may be
+ /// [`Self`], or a pointer type derived from [`Self`].
+ type CallbackTarget<'a>;
+
+ /// Callback to be called from C when timer fires.
+ ///
+ /// # Safety
+ ///
+ /// Only to be called by C code in the `hrtimer` subsystem. `this` must point
+ /// to the `bindings::hrtimer` structure that was used to start the timer.
+ unsafe extern "C" fn run(this: *mut bindings::hrtimer) -> bindings::hrtimer_restart;
+ }
+
+ /// Implemented by structs that can be the target of a timer callback.
+ pub trait HrTimerCallback {
+ /// The type whose [`RawHrTimerCallback::run`] method will be invoked when
+ /// the timer expires.
+ type Pointer<'a>: RawHrTimerCallback;
+
+ /// Called by the timer logic when the timer fires.
+ fn run(this: <Self::Pointer<'_> as RawHrTimerCallback>::CallbackTarget<'_>) -> HrTimerRestart
+ where
+ Self: Sized;
+ }
+
+ /// A handle representing a potentially running timer.
+ ///
+ /// More than one handle representing the same timer might exist.
+ ///
+ /// # Safety
+ ///
+ /// When dropped, the timer represented by this handle must be cancelled, if it
+ /// is running. If the timer handler is running when the handle is dropped, the
+ /// drop method must wait for the handler to return before returning.
+ ///
+ /// Note: One way to satisfy the safety requirement is to call `Self::cancel` in
+ /// the drop implementation for `Self.`
+ pub unsafe trait HrTimerHandle {
+ /// Cancel the timer. If the timer is in the running state, block till the
+ /// handler has returned.
+ ///
+ /// Note that the timer might be started by a concurrent start operation. If
+ /// so, the timer might not be in the **stopped** state when this function
+ /// returns.
+ fn cancel(&mut self) -> bool;
+ }
+
+ /// Implemented by structs that contain timer nodes.
+ ///
+ /// Clients of the timer API would usually safely implement this trait by using
+ /// the [`crate::impl_has_hr_timer`] macro.
+ ///
+ /// # Safety
+ ///
+ /// Implementers of this trait must ensure that the implementer has a
+ /// [`HrTimer`] field and that all trait methods are implemented according to
+ /// their documentation. All the methods of this trait must operate on the same
+ /// field.
+ pub unsafe trait HasHrTimer<T> {
+ /// Return a pointer to the [`HrTimer`] within `Self`.
+ ///
+ /// This function is useful to get access to the value without creating
+ /// intermediate references.
+ ///
+ /// # Safety
+ ///
+ /// `this` must be a valid pointer.
+ unsafe fn raw_get_timer(this: *const Self) -> *const HrTimer<T>;
+
+ /// Return a pointer to the struct that is containing the [`HrTimer`] pointed
+ /// to by `ptr`.
+ ///
+ /// This function is useful to get access to the value without creating
+ /// intermediate references.
+ ///
+ /// # Safety
+ ///
+ /// `ptr` must point to a [`HrTimer<T>`] field in a struct of type `Self`.
+ unsafe fn timer_container_of(ptr: *mut HrTimer<T>) -> *mut Self
+ where
+ Self: Sized;
+
+ /// Get pointer to the contained `bindings::hrtimer` struct.
+ ///
+ /// This function is useful to get access to the value without creating
+ /// intermediate references.
+ ///
+ /// # Safety
+ ///
+ /// `this` must be a valid pointer.
+ unsafe fn c_timer_ptr(this: *const Self) -> *const bindings::hrtimer {
+ // SAFETY: `this` is a valid pointer to a `Self`.
+ let timer_ptr = unsafe { Self::raw_get_timer(this) };
+
+ // SAFETY: timer_ptr points to an allocation of at least `HrTimer` size.
+ unsafe { HrTimer::raw_get(timer_ptr) }
+ }
+
+ /// Start the timer contained in the `Self` pointed to by `self_ptr`. If
+ /// it is already running it is removed and inserted.
+ ///
+ /// # Safety
+ ///
+ /// - `this` must point to a valid `Self`.
+ /// - Caller must ensure that the pointee of `this` lives until the timer
+ /// fires or is canceled.
+ unsafe fn start(this: *const Self, expires: Ktime) {
+ // SAFETY: By function safety requirement, `this` is a valid `Self`.
+ unsafe {
+ bindings::hrtimer_start_range_ns(
+ Self::c_timer_ptr(this).cast_mut(),
+ expires.to_ns(),
+ 0,
+ (*Self::raw_get_timer(this)).mode.into_c(),
+ );
+ }
+ }
+ }
+
+ /// Restart policy for timers.
+ #[derive(Copy, Clone, PartialEq, Eq, Debug)]
+ #[repr(u32)]
+ pub enum HrTimerRestart {
+ /// Timer should not be restarted.
+ #[allow(clippy::unnecessary_cast)]
+ NoRestart = bindings::hrtimer_restart_HRTIMER_NORESTART as u32,
+ /// Timer should be restarted.
+ #[allow(clippy::unnecessary_cast)]
+ Restart = bindings::hrtimer_restart_HRTIMER_RESTART as u32,
+ }
+
+ impl HrTimerRestart {
+ fn into_c(self) -> bindings::hrtimer_restart {
+ self as bindings::hrtimer_restart
+ }
+ }
+
+ /// Operational mode of [`HrTimer`].
+ // NOTE: Some of these have the same encoding on the C side, so we keep
+ // `repr(Rust)` and convert elsewhere.
+ #[derive(Clone, Copy, PartialEq, Eq, Debug)]
+ pub enum HrTimerMode {
+ /// Timer expires at the given expiration time.
+ Absolute,
+ /// Timer expires after the given expiration time interpreted as a duration from now.
+ Relative,
+ /// Timer does not move between CPU cores.
+ Pinned,
+ /// Timer handler is executed in soft irq context.
+ Soft,
+ /// Timer handler is executed in hard irq context.
+ Hard,
+ /// Timer expires at the given expiration time.
+ /// Timer does not move between CPU cores.
+ AbsolutePinned,
+ /// Timer expires after the given expiration time interpreted as a duration from now.
+ /// Timer does not move between CPU cores.
+ RelativePinned,
+ /// Timer expires at the given expiration time.
+ /// Timer handler is executed in soft irq context.
+ AbsoluteSoft,
+ /// Timer expires after the given expiration time interpreted as a duration from now.
+ /// Timer handler is executed in soft irq context.
+ RelativeSoft,
+ /// Timer expires at the given expiration time.
+ /// Timer does not move between CPU cores.
+ /// Timer handler is executed in soft irq context.
+ AbsolutePinnedSoft,
+ /// Timer expires after the given expiration time interpreted as a duration from now.
+ /// Timer does not move between CPU cores.
+ /// Timer handler is executed in soft irq context.
+ RelativePinnedSoft,
+ /// Timer expires at the given expiration time.
+ /// Timer handler is executed in hard irq context.
+ AbsoluteHard,
+ /// Timer expires after the given expiration time interpreted as a duration from now.
+ /// Timer handler is executed in hard irq context.
+ RelativeHard,
+ /// Timer expires at the given expiration time.
+ /// Timer does not move between CPU cores.
+ /// Timer handler is executed in hard irq context.
+ AbsolutePinnedHard,
+ /// Timer expires after the given expiration time interpreted as a duration from now.
+ /// Timer does not move between CPU cores.
+ /// Timer handler is executed in hard irq context.
+ RelativePinnedHard,
+ }
+
+ impl HrTimerMode {
+ fn into_c(self) -> bindings::hrtimer_mode {
+ use bindings::*;
+ match self {
+ HrTimerMode::Absolute => hrtimer_mode_HRTIMER_MODE_ABS,
+ HrTimerMode::Relative => hrtimer_mode_HRTIMER_MODE_REL,
+ HrTimerMode::Pinned => hrtimer_mode_HRTIMER_MODE_PINNED,
+ HrTimerMode::Soft => hrtimer_mode_HRTIMER_MODE_SOFT,
+ HrTimerMode::Hard => hrtimer_mode_HRTIMER_MODE_HARD,
+ HrTimerMode::AbsolutePinned => hrtimer_mode_HRTIMER_MODE_ABS_PINNED,
+ HrTimerMode::RelativePinned => hrtimer_mode_HRTIMER_MODE_REL_PINNED,
+ HrTimerMode::AbsoluteSoft => hrtimer_mode_HRTIMER_MODE_ABS_SOFT,
+ HrTimerMode::RelativeSoft => hrtimer_mode_HRTIMER_MODE_REL_SOFT,
+ HrTimerMode::AbsolutePinnedSoft => hrtimer_mode_HRTIMER_MODE_ABS_PINNED_SOFT,
+ HrTimerMode::RelativePinnedSoft => hrtimer_mode_HRTIMER_MODE_REL_PINNED_SOFT,
+ HrTimerMode::AbsoluteHard => hrtimer_mode_HRTIMER_MODE_ABS_HARD,
+ HrTimerMode::RelativeHard => hrtimer_mode_HRTIMER_MODE_REL_HARD,
+ HrTimerMode::AbsolutePinnedHard => hrtimer_mode_HRTIMER_MODE_ABS_PINNED_HARD,
+ HrTimerMode::RelativePinnedHard => hrtimer_mode_HRTIMER_MODE_REL_PINNED_HARD,
+ }
+ }
+ }
+
+ /// Use to implement the [`HasHrTimer<T>`] trait.
+ ///
+ /// See [`module`] documentation for an example.
+ ///
+ /// [`module`]: crate::time::hrtimer
+ #[macro_export]
+ macro_rules! impl_has_hr_timer {
+ (
+ impl$({$($generics:tt)*})?
+ HasHrTimer<$timer_type:ty>
+ for $self:ty
+ { self.$field:ident }
+ $($rest:tt)*
+ ) => {
+ // SAFETY: This implementation of `raw_get_timer` only compiles if the
+ // field has the right type.
+ unsafe impl$(<$($generics)*>)? $crate::time::hrtimer::HasHrTimer<$timer_type> for $self {
+
+ #[inline]
+ unsafe fn raw_get_timer(
+ this: *const Self,
+ ) -> *const $crate::time::hrtimer::HrTimer<$timer_type> {
+ // SAFETY: The caller promises that the pointer is not dangling.
+ unsafe { ::core::ptr::addr_of!((*this).$field) }
+ }
+
+ #[inline]
+ unsafe fn timer_container_of(
+ ptr: *mut $crate::time::hrtimer::HrTimer<$timer_type>,
+ ) -> *mut Self {
+ // SAFETY: As per the safety requirement of this function, `ptr`
+ // is pointing inside a `$timer_type`.
+ unsafe { ::kernel::container_of!(ptr, $timer_type, $field).cast_mut() }
+ }
+ }
+ }
+ }
+
+ mod arc;
+ pub use arc::ArcHrTimerHandle;
+ mod pin;
+ pub use pin::PinHrTimerHandle;
+ mod pin_mut;
+ pub use pin_mut::PinMutHrTimerHandle;
+ // `box` is a reserved keyword, so prefix with `t` for timer
+ mod tbox;
+ pub use tbox::BoxHrTimerHandle;
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