Resguardo inicial

linux-7.2.3/rust/kernel/irq/flags.rs

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+// SPDX-License-Identifier: GPL-2.0
+// SPDX-FileCopyrightText: Copyright 2025 Collabora ltd.
+
+use crate::bindings;
+use crate::prelude::*;
+
+/// Flags to be used when registering IRQ handlers.
+///
+/// Flags can be used to request specific behaviors when registering an IRQ
+/// handler, and can be combined using the `|`, `&`, and `!` operators to
+/// further control the system's behavior.
+///
+/// A common use case is to register a shared interrupt, as sharing the line
+/// between devices is increasingly common in modern systems and is even
+/// required for some buses. This requires setting [`Flags::SHARED`] when
+/// requesting the interrupt. Other use cases include setting the trigger type
+/// through `Flags::TRIGGER_*`, which determines when the interrupt fires, or
+/// controlling whether the interrupt is masked after the handler runs by using
+/// [`Flags::ONESHOT`].
+///
+/// If an invalid combination of flags is provided, the system will refuse to
+/// register the handler, and lower layers will enforce certain flags when
+/// necessary. This means, for example, that all the
+/// [`crate::irq::Registration`] for a shared interrupt have to agree on
+/// [`Flags::SHARED`] and on the same trigger type, if set.
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct Flags(c_ulong);
+
+impl Flags {
+    /// Use the interrupt line as already configured.
+    pub const TRIGGER_NONE: Flags = Flags::new(bindings::IRQF_TRIGGER_NONE);
+
+    /// The interrupt is triggered when the signal goes from low to high.
+    pub const TRIGGER_RISING: Flags = Flags::new(bindings::IRQF_TRIGGER_RISING);
+
+    /// The interrupt is triggered when the signal goes from high to low.
+    pub const TRIGGER_FALLING: Flags = Flags::new(bindings::IRQF_TRIGGER_FALLING);
+
+    /// The interrupt is triggered while the signal is held high.
+    pub const TRIGGER_HIGH: Flags = Flags::new(bindings::IRQF_TRIGGER_HIGH);
+
+    /// The interrupt is triggered while the signal is held low.
+    pub const TRIGGER_LOW: Flags = Flags::new(bindings::IRQF_TRIGGER_LOW);
+
+    /// Allow sharing the IRQ among several devices.
+    pub const SHARED: Flags = Flags::new(bindings::IRQF_SHARED);
+
+    /// Set by callers when they expect sharing mismatches to occur.
+    pub const PROBE_SHARED: Flags = Flags::new(bindings::IRQF_PROBE_SHARED);
+
+    /// Flag to mark this interrupt as timer interrupt.
+    pub const TIMER: Flags = Flags::new(bindings::IRQF_TIMER);
+
+    /// Interrupt is per CPU.
+    pub const PERCPU: Flags = Flags::new(bindings::IRQF_PERCPU);
+
+    /// Flag to exclude this interrupt from irq balancing.
+    pub const NOBALANCING: Flags = Flags::new(bindings::IRQF_NOBALANCING);
+
+    /// Interrupt is used for polling (only the interrupt that is registered
+    /// first in a shared interrupt is considered for performance reasons).
+    pub const IRQPOLL: Flags = Flags::new(bindings::IRQF_IRQPOLL);
+
+    /// Interrupt is not re-enabled after the hardirq handler finished. Used by
+    /// threaded interrupts which need to keep the irq line disabled until the
+    /// threaded handler has been run.
+    pub const ONESHOT: Flags = Flags::new(bindings::IRQF_ONESHOT);
+
+    /// Do not disable this IRQ during suspend. Does not guarantee that this
+    /// interrupt will wake the system from a suspended state.
+    pub const NO_SUSPEND: Flags = Flags::new(bindings::IRQF_NO_SUSPEND);
+
+    /// Force enable it on resume even if [`Flags::NO_SUSPEND`] is set.
+    pub const FORCE_RESUME: Flags = Flags::new(bindings::IRQF_FORCE_RESUME);
+
+    /// Interrupt cannot be threaded.
+    pub const NO_THREAD: Flags = Flags::new(bindings::IRQF_NO_THREAD);
+
+    /// Resume IRQ early during syscore instead of at device resume time.
+    pub const EARLY_RESUME: Flags = Flags::new(bindings::IRQF_EARLY_RESUME);
+
+    /// If the IRQ is shared with a [`Flags::NO_SUSPEND`] user, execute this
+    /// interrupt handler after suspending interrupts. For system wakeup devices
+    /// users need to implement wakeup detection in their interrupt handlers.
+    pub const COND_SUSPEND: Flags = Flags::new(bindings::IRQF_COND_SUSPEND);
+
+    /// Don't enable IRQ or NMI automatically when users request it. Users will
+    /// enable it explicitly by `enable_irq` or `enable_nmi` later.
+    pub const NO_AUTOEN: Flags = Flags::new(bindings::IRQF_NO_AUTOEN);
+
+    /// Exclude from runnaway detection for IPI and similar handlers, depends on
+    /// `PERCPU`.
+    pub const NO_DEBUG: Flags = Flags::new(bindings::IRQF_NO_DEBUG);
+
+    pub(crate) fn into_inner(self) -> c_ulong {
+        self.0
+    }
+
+    // Always inline to optimize out error path of `build_assert`.
+    #[inline(always)]
+    const fn new(value: u32) -> Self {
+        build_assert!(value as u64 <= c_ulong::MAX as u64);
+        Self(value as c_ulong)
+    }
+}
+
+impl core::ops::BitOr for Flags {
+    type Output = Self;
+    fn bitor(self, rhs: Self) -> Self::Output {
+        Self(self.0 | rhs.0)
+    }
+}
+
+impl core::ops::BitAnd for Flags {
+    type Output = Self;
+    fn bitand(self, rhs: Self) -> Self::Output {
+        Self(self.0 & rhs.0)
+    }
+}
+
+impl core::ops::Not for Flags {
+    type Output = Self;
+    fn not(self) -> Self::Output {
+        Self(!self.0)
+    }
+}

linux-7.2.3/rust/kernel/irq/request.rs

@@ -0,0 +1,505 @@
+// SPDX-License-Identifier: GPL-2.0
+// SPDX-FileCopyrightText: Copyright 2025 Collabora ltd.
+
+//! This module provides types like [`Registration`] and
+//! [`ThreadedRegistration`], which allow users to register handlers for a given
+//! IRQ line.
+
+use core::marker::PhantomPinned;
+
+use crate::alloc::Allocator;
+use crate::device::{Bound, Device};
+use crate::devres::Devres;
+use crate::error::to_result;
+use crate::irq::flags::Flags;
+use crate::prelude::*;
+use crate::str::CStr;
+use crate::sync::Arc;
+
+/// The value that can be returned from a [`Handler`] or a [`ThreadedHandler`].
+#[repr(u32)]
+pub enum IrqReturn {
+    /// The interrupt was not from this device or was not handled.
+    None = bindings::irqreturn_IRQ_NONE,
+
+    /// The interrupt was handled by this device.
+    Handled = bindings::irqreturn_IRQ_HANDLED,
+}
+
+/// Callbacks for an IRQ handler.
+pub trait Handler: Sync + 'static {
+    /// The hard IRQ handler.
+    ///
+    /// This is executed in interrupt context, hence all corresponding
+    /// limitations do apply.
+    ///
+    /// All work that does not necessarily need to be executed from
+    /// interrupt context, should be deferred to a threaded handler.
+    /// See also [`ThreadedRegistration`].
+    fn handle(&self, device: &Device<Bound>) -> IrqReturn;
+}
+
+impl<T: ?Sized + Handler + Send> Handler for Arc<T> {
+    fn handle(&self, device: &Device<Bound>) -> IrqReturn {
+        T::handle(self, device)
+    }
+}
+
+impl<T: ?Sized + Handler, A: Allocator + 'static> Handler for Box<T, A> {
+    fn handle(&self, device: &Device<Bound>) -> IrqReturn {
+        T::handle(self, device)
+    }
+}
+
+/// # Invariants
+///
+/// - `self.irq` is the same as the one passed to `request_{threaded}_irq`.
+/// - `cookie` was passed to `request_{threaded}_irq` as the cookie. It is guaranteed to be unique
+///   by the type system, since each call to `new` will return a different instance of
+///   `Registration`.
+#[pin_data(PinnedDrop)]
+struct RegistrationInner {
+    irq: u32,
+    cookie: *mut c_void,
+}
+
+impl RegistrationInner {
+    fn synchronize(&self) {
+        // SAFETY: safe as per the invariants of `RegistrationInner`
+        unsafe { bindings::synchronize_irq(self.irq) };
+    }
+}
+
+#[pinned_drop]
+impl PinnedDrop for RegistrationInner {
+    fn drop(self: Pin<&mut Self>) {
+        // SAFETY:
+        //
+        // Safe as per the invariants of `RegistrationInner` and:
+        //
+        // - The containing struct is `!Unpin` and was initialized using
+        // pin-init, so it occupied the same memory location for the entirety of
+        // its lifetime.
+        //
+        // Notice that this will block until all handlers finish executing,
+        // i.e.: at no point will &self be invalid while the handler is running.
+        unsafe { bindings::free_irq(self.irq, self.cookie) };
+    }
+}
+
+// SAFETY: We only use `inner` on drop, which called at most once with no
+// concurrent access.
+unsafe impl Sync for RegistrationInner {}
+
+// SAFETY: It is safe to send `RegistrationInner` across threads.
+unsafe impl Send for RegistrationInner {}
+
+/// A request for an IRQ line for a given device.
+///
+/// # Invariants
+///
+/// - `ìrq` is the number of an interrupt source of `dev`.
+/// - `irq` has not been registered yet.
+pub struct IrqRequest<'a> {
+    dev: &'a Device<Bound>,
+    irq: u32,
+}
+
+impl<'a> IrqRequest<'a> {
+    /// Creates a new IRQ request for the given device and IRQ number.
+    ///
+    /// # Safety
+    ///
+    /// - `irq` should be a valid IRQ number for `dev`.
+    pub(crate) unsafe fn new(dev: &'a Device<Bound>, irq: u32) -> Self {
+        // INVARIANT: `irq` is a valid IRQ number for `dev`.
+        IrqRequest { dev, irq }
+    }
+
+    /// Returns the IRQ number of an [`IrqRequest`].
+    pub fn irq(&self) -> u32 {
+        self.irq
+    }
+}
+
+/// A registration of an IRQ handler for a given IRQ line.
+///
+/// # Examples
+///
+/// The following is an example of using `Registration`. It uses a
+/// [`Completion`] to coordinate between the IRQ
+/// handler and process context. [`Completion`] uses interior mutability, so the
+/// handler can signal with [`Completion::complete_all()`] and the process
+/// context can wait with [`Completion::wait_for_completion()`] even though
+/// there is no way to get a mutable reference to the any of the fields in
+/// `Data`.
+///
+/// [`Completion`]: kernel::sync::Completion
+/// [`Completion::complete_all()`]: kernel::sync::Completion::complete_all
+/// [`Completion::wait_for_completion()`]: kernel::sync::Completion::wait_for_completion
+///
+/// ```
+/// use kernel::device::{Bound, Device};
+/// use kernel::irq::{self, Flags, IrqRequest, IrqReturn, Registration};
+/// use kernel::prelude::*;
+/// use kernel::sync::{Arc, Completion};
+///
+/// // Data shared between process and IRQ context.
+/// #[pin_data]
+/// struct Data {
+///     #[pin]
+///     completion: Completion,
+/// }
+///
+/// impl irq::Handler for Data {
+///     // Executed in IRQ context.
+///     fn handle(&self, _dev: &Device<Bound>) -> IrqReturn {
+///         self.completion.complete_all();
+///         IrqReturn::Handled
+///     }
+/// }
+///
+/// // Registers an IRQ handler for the given IrqRequest.
+/// //
+/// // This runs in process context and assumes `request` was previously acquired from a device.
+/// fn register_irq(
+///     handler: impl PinInit<Data, Error>,
+///     request: IrqRequest<'_>,
+/// ) -> Result<Arc<Registration<Data>>> {
+///     let registration = Registration::new(request, Flags::SHARED, c"my_device", handler);
+///
+///     let registration = Arc::pin_init(registration, GFP_KERNEL)?;
+///
+///     registration.handler().completion.wait_for_completion();
+///
+///     Ok(registration)
+/// }
+/// # Ok::<(), Error>(())
+/// ```
+///
+/// # Invariants
+///
+/// * We own an irq handler whose cookie is a pointer to `Self`.
+#[pin_data]
+pub struct Registration<T: Handler> {
+    #[pin]
+    inner: Devres<RegistrationInner>,
+
+    #[pin]
+    handler: T,
+
+    /// Pinned because we need address stability so that we can pass a pointer
+    /// to the callback.
+    #[pin]
+    _pin: PhantomPinned,
+}
+
+impl<T: Handler> Registration<T> {
+    /// Registers the IRQ handler with the system for the given IRQ number.
+    pub fn new<'a>(
+        request: IrqRequest<'a>,
+        flags: Flags,
+        name: &'static CStr,
+        handler: impl PinInit<T, Error> + 'a,
+    ) -> impl PinInit<Self, Error> + 'a {
+        try_pin_init!(&this in Self {
+            handler <- handler,
+            inner <- Devres::new(
+                request.dev,
+                try_pin_init!(RegistrationInner {
+                    // INVARIANT: `this` is a valid pointer to the `Registration` instance
+                    cookie: this.as_ptr().cast::<c_void>(),
+                    irq: {
+                        // SAFETY:
+                        // - The callbacks are valid for use with request_irq.
+                        // - If this succeeds, the slot is guaranteed to be valid until the
+                        //   destructor of Self runs, which will deregister the callbacks
+                        //   before the memory location becomes invalid.
+                        // - When request_irq is called, everything that handle_irq_callback will
+                        //   touch has already been initialized, so it's safe for the callback to
+                        //   be called immediately.
+                        to_result(unsafe {
+                            bindings::request_irq(
+                                request.irq,
+                                Some(handle_irq_callback::<T>),
+                                flags.into_inner(),
+                                name.as_char_ptr(),
+                                this.as_ptr().cast::<c_void>(),
+                            )
+                        })?;
+                        request.irq
+                    }
+                })
+            ),
+            _pin: PhantomPinned,
+        })
+    }
+
+    /// Returns a reference to the handler that was registered with the system.
+    pub fn handler(&self) -> &T {
+        &self.handler
+    }
+
+    /// Wait for pending IRQ handlers on other CPUs.
+    ///
+    /// This will attempt to access the inner [`Devres`] container.
+    pub fn try_synchronize(&self) -> Result {
+        let inner = self.inner.try_access().ok_or(ENODEV)?;
+        inner.synchronize();
+        Ok(())
+    }
+
+    /// Wait for pending IRQ handlers on other CPUs.
+    pub fn synchronize(&self, dev: &Device<Bound>) -> Result {
+        let inner = self.inner.access(dev)?;
+        inner.synchronize();
+        Ok(())
+    }
+}
+
+/// # Safety
+///
+/// This function should be only used as the callback in `request_irq`.
+unsafe extern "C" fn handle_irq_callback<T: Handler>(_irq: i32, ptr: *mut c_void) -> c_uint {
+    // SAFETY: `ptr` is a pointer to `Registration<T>` set in `Registration::new`
+    let registration = unsafe { &*(ptr as *const Registration<T>) };
+    // SAFETY: The irq callback is removed before the device is unbound, so the fact that the irq
+    // callback is running implies that the device has not yet been unbound.
+    let device = unsafe { registration.inner.device().as_bound() };
+
+    T::handle(&registration.handler, device) as c_uint
+}
+
+/// The value that can be returned from [`ThreadedHandler::handle`].
+#[repr(u32)]
+pub enum ThreadedIrqReturn {
+    /// The interrupt was not from this device or was not handled.
+    None = bindings::irqreturn_IRQ_NONE,
+
+    /// The interrupt was handled by this device.
+    Handled = bindings::irqreturn_IRQ_HANDLED,
+
+    /// The handler wants the handler thread to wake up.
+    WakeThread = bindings::irqreturn_IRQ_WAKE_THREAD,
+}
+
+/// Callbacks for a threaded IRQ handler.
+pub trait ThreadedHandler: Sync + 'static {
+    /// The hard IRQ handler.
+    ///
+    /// This is executed in interrupt context, hence all corresponding
+    /// limitations do apply. All work that does not necessarily need to be
+    /// executed from interrupt context, should be deferred to the threaded
+    /// handler, i.e. [`ThreadedHandler::handle_threaded`].
+    ///
+    /// The default implementation returns [`ThreadedIrqReturn::WakeThread`].
+    #[expect(unused_variables)]
+    fn handle(&self, device: &Device<Bound>) -> ThreadedIrqReturn {
+        ThreadedIrqReturn::WakeThread
+    }
+
+    /// The threaded IRQ handler.
+    ///
+    /// This is executed in process context. The kernel creates a dedicated
+    /// `kthread` for this purpose.
+    fn handle_threaded(&self, device: &Device<Bound>) -> IrqReturn;
+}
+
+impl<T: ?Sized + ThreadedHandler + Send> ThreadedHandler for Arc<T> {
+    fn handle(&self, device: &Device<Bound>) -> ThreadedIrqReturn {
+        T::handle(self, device)
+    }
+
+    fn handle_threaded(&self, device: &Device<Bound>) -> IrqReturn {
+        T::handle_threaded(self, device)
+    }
+}
+
+impl<T: ?Sized + ThreadedHandler, A: Allocator + 'static> ThreadedHandler for Box<T, A> {
+    fn handle(&self, device: &Device<Bound>) -> ThreadedIrqReturn {
+        T::handle(self, device)
+    }
+
+    fn handle_threaded(&self, device: &Device<Bound>) -> IrqReturn {
+        T::handle_threaded(self, device)
+    }
+}
+
+/// A registration of a threaded IRQ handler for a given IRQ line.
+///
+/// Two callbacks are required: one to handle the IRQ, and one to handle any
+/// other work in a separate thread.
+///
+/// The thread handler is only called if the IRQ handler returns
+/// [`ThreadedIrqReturn::WakeThread`].
+///
+/// # Examples
+///
+/// The following is an example of using [`ThreadedRegistration`]. It uses a
+/// [`Mutex`](kernel::sync::Mutex) to provide interior mutability.
+///
+/// ```
+/// use kernel::device::{Bound, Device};
+/// use kernel::irq::{
+///   self, Flags, IrqRequest, IrqReturn, ThreadedHandler, ThreadedIrqReturn,
+///   ThreadedRegistration,
+/// };
+/// use kernel::prelude::*;
+/// use kernel::sync::{Arc, Mutex};
+///
+/// // Declare a struct that will be passed in when the interrupt fires. The u32
+/// // merely serves as an example of some internal data.
+/// //
+/// // [`irq::ThreadedHandler::handle`] takes `&self`. This example
+/// // illustrates how interior mutability can be used when sharing the data
+/// // between process context and IRQ context.
+/// #[pin_data]
+/// struct Data {
+///     #[pin]
+///     value: Mutex<u32>,
+/// }
+///
+/// impl ThreadedHandler for Data {
+///     // This will run (in a separate kthread) if and only if
+///     // [`ThreadedHandler::handle`] returns [`WakeThread`], which it does by
+///     // default.
+///     fn handle_threaded(&self, _dev: &Device<Bound>) -> IrqReturn {
+///         let mut data = self.value.lock();
+///         *data += 1;
+///         IrqReturn::Handled
+///     }
+/// }
+///
+/// // Registers a threaded IRQ handler for the given [`IrqRequest`].
+/// //
+/// // This is executing in process context and assumes that `request` was
+/// // previously acquired from a device.
+/// fn register_threaded_irq(
+///     handler: impl PinInit<Data, Error>,
+///     request: IrqRequest<'_>,
+/// ) -> Result<Arc<ThreadedRegistration<Data>>> {
+///     let registration =
+///         ThreadedRegistration::new(request, Flags::SHARED, c"my_device", handler);
+///
+///     let registration = Arc::pin_init(registration, GFP_KERNEL)?;
+///
+///     {
+///         // The data can be accessed from process context too.
+///         let mut data = registration.handler().value.lock();
+///         *data += 1;
+///     }
+///
+///     Ok(registration)
+/// }
+/// # Ok::<(), Error>(())
+/// ```
+///
+/// # Invariants
+///
+/// * We own an irq handler whose cookie is a pointer to `Self`.
+#[pin_data]
+pub struct ThreadedRegistration<T: ThreadedHandler> {
+    #[pin]
+    inner: Devres<RegistrationInner>,
+
+    #[pin]
+    handler: T,
+
+    /// Pinned because we need address stability so that we can pass a pointer
+    /// to the callback.
+    #[pin]
+    _pin: PhantomPinned,
+}
+
+impl<T: ThreadedHandler> ThreadedRegistration<T> {
+    /// Registers the IRQ handler with the system for the given IRQ number.
+    pub fn new<'a>(
+        request: IrqRequest<'a>,
+        flags: Flags,
+        name: &'static CStr,
+        handler: impl PinInit<T, Error> + 'a,
+    ) -> impl PinInit<Self, Error> + 'a {
+        try_pin_init!(&this in Self {
+            handler <- handler,
+            inner <- Devres::new(
+                request.dev,
+                try_pin_init!(RegistrationInner {
+                    // INVARIANT: `this` is a valid pointer to the `ThreadedRegistration` instance.
+                    cookie: this.as_ptr().cast::<c_void>(),
+                    irq: {
+                        // SAFETY:
+                        // - The callbacks are valid for use with request_threaded_irq.
+                        // - If this succeeds, the slot is guaranteed to be valid until the
+                        //   destructor of Self runs, which will deregister the callbacks
+                        //   before the memory location becomes invalid.
+                        // - When request_threaded_irq is called, everything that the two callbacks
+                        //   will touch has already been initialized, so it's safe for the
+                        //   callbacks to be called immediately.
+                        to_result(unsafe {
+                            bindings::request_threaded_irq(
+                                request.irq,
+                                Some(handle_threaded_irq_callback::<T>),
+                                Some(thread_fn_callback::<T>),
+                                flags.into_inner(),
+                                name.as_char_ptr(),
+                                this.as_ptr().cast::<c_void>(),
+                            )
+                        })?;
+                        request.irq
+                    }
+                })
+            ),
+            _pin: PhantomPinned,
+        })
+    }
+
+    /// Returns a reference to the handler that was registered with the system.
+    pub fn handler(&self) -> &T {
+        &self.handler
+    }
+
+    /// Wait for pending IRQ handlers on other CPUs.
+    ///
+    /// This will attempt to access the inner [`Devres`] container.
+    pub fn try_synchronize(&self) -> Result {
+        let inner = self.inner.try_access().ok_or(ENODEV)?;
+        inner.synchronize();
+        Ok(())
+    }
+
+    /// Wait for pending IRQ handlers on other CPUs.
+    pub fn synchronize(&self, dev: &Device<Bound>) -> Result {
+        let inner = self.inner.access(dev)?;
+        inner.synchronize();
+        Ok(())
+    }
+}
+
+/// # Safety
+///
+/// This function should be only used as the callback in `request_threaded_irq`.
+unsafe extern "C" fn handle_threaded_irq_callback<T: ThreadedHandler>(
+    _irq: i32,
+    ptr: *mut c_void,
+) -> c_uint {
+    // SAFETY: `ptr` is a pointer to `ThreadedRegistration<T>` set in `ThreadedRegistration::new`
+    let registration = unsafe { &*(ptr as *const ThreadedRegistration<T>) };
+    // SAFETY: The irq callback is removed before the device is unbound, so the fact that the irq
+    // callback is running implies that the device has not yet been unbound.
+    let device = unsafe { registration.inner.device().as_bound() };
+
+    T::handle(&registration.handler, device) as c_uint
+}
+
+/// # Safety
+///
+/// This function should be only used as the callback in `request_threaded_irq`.
+unsafe extern "C" fn thread_fn_callback<T: ThreadedHandler>(_irq: i32, ptr: *mut c_void) -> c_uint {
+    // SAFETY: `ptr` is a pointer to `ThreadedRegistration<T>` set in `ThreadedRegistration::new`
+    let registration = unsafe { &*(ptr as *const ThreadedRegistration<T>) };
+    // SAFETY: The irq callback is removed before the device is unbound, so the fact that the irq
+    // callback is running implies that the device has not yet been unbound.
+    let device = unsafe { registration.inner.device().as_bound() };
+
+    T::handle_threaded(&registration.handler, device) as c_uint
+}