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Message-Id: <20241024-topic-panthor-rs-request_irq-v1-1-7cbc51c182ca@collabora.com>
Date: Thu, 24 Oct 2024 11:20:02 -0300
From: Daniel Almeida <daniel.almeida@...labora.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org,
Daniel Almeida <daniel.almeida@...labora.com>
Subject: [PATCH] rust: irq: add support for request_irq()
Both regular and threaded versions are supported.
Signed-off-by: Daniel Almeida <daniel.almeida@...labora.com>
---
rust/bindings/bindings_helper.h | 1 +
rust/helpers/helpers.c | 1 +
rust/helpers/irq.c | 9 +
rust/kernel/irq.rs | 6 +
rust/kernel/irq/request.rs | 450 ++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
6 files changed, 468 insertions(+)
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index ae82e9c941afa17c48737d2b2e49ac6d26f670b1..f1c35b334f5f7d2adcacb1def72182a09db2ac6c 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -13,6 +13,7 @@
#include <linux/errname.h>
#include <linux/ethtool.h>
#include <linux/firmware.h>
+#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/mdio.h>
#include <linux/phy.h>
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index 30f40149f3a969f9e8eb747aabdc17a8cb06936b..0bb48df454bd87def8271444ea58c781b792e34c 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -12,6 +12,7 @@
#include "build_assert.c"
#include "build_bug.c"
#include "err.c"
+#include "irq.c"
#include "kunit.c"
#include "mutex.c"
#include "page.c"
diff --git a/rust/helpers/irq.c b/rust/helpers/irq.c
new file mode 100644
index 0000000000000000000000000000000000000000..1faca428e2c047a656dec3171855c1508d67e60b
--- /dev/null
+++ b/rust/helpers/irq.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/interrupt.h>
+
+int rust_helper_request_irq(unsigned int irq, irq_handler_t handler,
+ unsigned long flags, const char *name, void *dev)
+{
+ return request_irq(irq, handler, flags, name, dev);
+}
diff --git a/rust/kernel/irq.rs b/rust/kernel/irq.rs
new file mode 100644
index 0000000000000000000000000000000000000000..3ab83c5bdb831e84f5e035d9ef56f8e373fa572d
--- /dev/null
+++ b/rust/kernel/irq.rs
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! IRQ abstractions
+
+/// IRQ allocation and handling
+pub mod request;
diff --git a/rust/kernel/irq/request.rs b/rust/kernel/irq/request.rs
new file mode 100644
index 0000000000000000000000000000000000000000..4b5c5b80c3f43d482132423c2c52cfa5696b7661
--- /dev/null
+++ b/rust/kernel/irq/request.rs
@@ -0,0 +1,450 @@
+// SPDX-License-Identifier: GPL-2.0
+// SPDX-FileCopyrightText: Copyright 2019 Collabora ltd.
+
+//! IRQ allocation and handling
+
+use crate::error::to_result;
+use crate::prelude::*;
+use crate::str::CStr;
+use crate::types::Opaque;
+
+/// Flags to be used when registering IRQ handlers.
+///
+/// They can be combined with the operators `|`, `&`, and `!`.
+///
+/// Values can be used from the [`flags`] module.
+#[derive(Clone, Copy)]
+pub struct Flags(u64);
+
+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)
+ }
+}
+
+/// The flags that can be used when registering an IRQ handler.
+pub mod flags {
+ use super::Flags;
+
+ use crate::bindings;
+
+ /// Use the interrupt line as already configured.
+ pub const TRIGGER_NONE: Flags = Flags(bindings::IRQF_TRIGGER_NONE as _);
+
+ /// The interrupt is triggered when the signal goes from low to high.
+ pub const TRIGGER_RISING: Flags = Flags(bindings::IRQF_TRIGGER_RISING as _);
+
+ /// The interrupt is triggered when the signal goes from high to low.
+ pub const TRIGGER_FALLING: Flags = Flags(bindings::IRQF_TRIGGER_FALLING as _);
+
+ /// The interrupt is triggered while the signal is held high.
+ pub const TRIGGER_HIGH: Flags = Flags(bindings::IRQF_TRIGGER_HIGH as _);
+
+ /// The interrupt is triggered while the signal is held low.
+ pub const TRIGGER_LOW: Flags = Flags(bindings::IRQF_TRIGGER_LOW as _);
+
+ /// Allow sharing the irq among several devices.
+ pub const SHARED: Flags = Flags(bindings::IRQF_SHARED as _);
+
+ /// Set by callers when they expect sharing mismatches to occur.
+ pub const PROBE_SHARED: Flags = Flags(bindings::IRQF_PROBE_SHARED as _);
+
+ /// Flag to mark this interrupt as timer interrupt.
+ pub const TIMER: Flags = Flags(bindings::IRQF_TIMER as _);
+
+ /// Interrupt is per cpu.
+ pub const PERCPU: Flags = Flags(bindings::IRQF_PERCPU as _);
+
+ /// Flag to exclude this interrupt from irq balancing.
+ pub const NOBALANCING: Flags = Flags(bindings::IRQF_NOBALANCING as _);
+
+ /// 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(bindings::IRQF_IRQPOLL as _);
+
+ /// Interrupt is not reenabled 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(bindings::IRQF_ONESHOT as _);
+
+ /// 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(bindings::IRQF_NO_SUSPEND as _);
+
+ /// Force enable it on resume even if [`NO_SUSPEND`] is set.
+ pub const FORCE_RESUME: Flags = Flags(bindings::IRQF_FORCE_RESUME as _);
+
+ /// Interrupt cannot be threaded.
+ pub const NO_THREAD: Flags = Flags(bindings::IRQF_NO_THREAD as _);
+
+ /// Resume IRQ early during syscore instead of at device resume time.
+ pub const EARLY_RESUME: Flags = Flags(bindings::IRQF_EARLY_RESUME as _);
+
+ /// If the IRQ is shared with a 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(bindings::IRQF_COND_SUSPEND as _);
+
+ /// 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(bindings::IRQF_NO_AUTOEN as _);
+
+ /// Exclude from runnaway detection for IPI and similar handlers, depends on
+ /// `PERCPU`.
+ pub const NO_DEBUG: Flags = Flags(bindings::IRQF_NO_DEBUG as _);
+}
+
+/// The value that can be returned from an IrqHandler;
+pub enum IrqReturn {
+ /// The interrupt was not from this device or was not handled.
+ None = bindings::irqreturn_IRQ_NONE as _,
+
+ /// The interrupt was handled by this device.
+ Handled = bindings::irqreturn_IRQ_HANDLED as _,
+}
+
+/// Callbacks for an IRQ handler.
+pub trait Handler: Sync {
+ /// The actual handler function. As usual, sleeps are not allowed in IRQ
+ /// context.
+ fn handle_irq(&self) -> IrqReturn;
+}
+
+/// A registration of an IRQ handler for a given IRQ line.
+///
+/// # Invariants
+///
+/// * We own an irq handler using `&self` as its private data.
+///
+/// # Examples
+///
+/// The following is an example of using `Registration`:
+///
+/// ```
+/// use kernel::prelude::*;
+/// use kernel::irq;
+/// use kernel::irq::Registration;
+/// use kernel::sync::Arc;
+/// use kernel::sync::lock::SpinLock;
+///
+/// // Declare a struct that will be passed in when the interrupt fires. The u32
+/// // merely serves as an example of some internal data.
+/// struct Data(u32);
+///
+/// // [`handle_irq`] returns &self. This example illustrates interior
+/// // mutability can be used when share the data between process context and IRQ
+/// // context.
+/// //
+/// // Ideally, this example would be using a version of SpinLock that is aware
+/// // of `spin_lock_irqsave` and `spin_lock_irqrestore`, but that is not yet
+/// // implemented.
+///
+/// type Handler = SpinLock<Data>;
+///
+/// impl kernel::irq::Handler for Handler {
+/// // This is executing in IRQ context in some CPU. Other CPUs can still
+/// // try to access to data.
+/// fn handle_irq(&self) -> irq::IrqReturn {
+/// // We now have exclusive access to the data by locking the SpinLock.
+/// let mut handler = self.lock();
+/// handler.0 += 1;
+///
+/// IrqReturn::Handled
+/// }
+/// }
+///
+/// // This is running in process context.
+/// fn register_irq(irq: u32, handler: Handler) -> Result<irq::Registration<Handler>> {
+/// let registration = Registration::register(irq, irq::flags::SHARED, "my-device", handler)?;
+///
+/// // You can have as many references to the registration as you want, so
+/// // multiple parts of the driver can access it.
+/// let registration = Arc::pin_init(registration)?;
+///
+/// // The handler may be called immediately after the function above
+/// // returns, possibly in a different CPU.
+///
+/// // The data can be accessed from the process context too.
+/// registration.handler().lock().0 = 42;
+///
+/// Ok(registration)
+/// }
+///
+/// # Ok::<(), Error>(())
+///```
+#[pin_data(PinnedDrop)]
+pub struct Registration<T: Handler> {
+ irq: u32,
+ #[pin]
+ handler: Opaque<T>,
+}
+
+impl<T: Handler> Registration<T> {
+ /// Registers the IRQ handler with the system for the given IRQ number. The
+ /// handler must be able to be called as soon as this function returns.
+ pub fn register(
+ irq: u32,
+ flags: Flags,
+ name: &'static CStr,
+ handler: T,
+ ) -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {
+ irq,
+ handler: Opaque::new(handler)
+ })
+ .pin_chain(move |slot| {
+ // SAFETY:
+ // - `handler` points to a valid function defined below.
+ // - only valid flags can be constructed using the `flags` module.
+ // - `devname` is a nul-terminated string with a 'static lifetime.
+ // - `ptr` is a cookie used to identify the handler. The same cookie is
+ // passed back when the system calls the handler.
+ to_result(unsafe {
+ bindings::request_irq(
+ irq,
+ Some(handle_irq_callback::<T>),
+ flags.0,
+ name.as_char_ptr(),
+ &*slot as *const _ as *mut core::ffi::c_void,
+ )
+ })?;
+
+ Ok(())
+ })
+ }
+
+ /// Returns a reference to the handler that was registered with the system.
+ pub fn handler(&self) -> &T {
+ // SAFETY: `handler` is initialized in `register`.
+ unsafe { &*self.handler.get() }
+ }
+}
+
+#[pinned_drop]
+impl<T: Handler> PinnedDrop for Registration<T> {
+ fn drop(self: Pin<&mut Self>) {
+ // SAFETY:
+ // - `self.irq` is the same as the one passed to `reques_irq`.
+ // - `&self` was passed to `request_irq` as the cookie. It is
+ // guaranteed to be unique by the type system, since each call to
+ // `register` will return a different instance of `Registration`.
+ //
+ // Notice that this will block until all handlers finish executing, so,
+ // at no point will &self be invalid while the handler is running.
+ unsafe { bindings::free_irq(self.irq, &*self as *const _ as *mut core::ffi::c_void) };
+ }
+}
+
+/// The value that can be returned from `ThreadedHandler::handle_irq`.
+pub enum ThreadedIrqReturn {
+ /// The interrupt was not from this device or was not handled.
+ None = bindings::irqreturn_IRQ_NONE as _,
+
+ /// The interrupt was handled by this device.
+ Handled = bindings::irqreturn_IRQ_HANDLED as _,
+
+ /// The handler wants the handler thread to wake up.
+ WakeThread = bindings::irqreturn_IRQ_WAKE_THREAD as _,
+}
+
+/// The value that can be returned from `ThreadedFnHandler::thread_fn`.
+pub enum ThreadedFnReturn {
+ /// The thread function did not make any progress.
+ None = bindings::irqreturn_IRQ_NONE as _,
+
+ /// The thread function ran successfully.
+ Handled = bindings::irqreturn_IRQ_HANDLED as _,
+}
+
+/// Callbacks for a threaded IRQ handler.
+pub trait ThreadedHandler: Sync {
+ /// The actual handler function. As usual, sleeps are not allowed in IRQ
+ /// context.
+ fn handle_irq(&self) -> ThreadedIrqReturn;
+
+ /// The threaded handler function. This function is called from the irq
+ /// handler thread, which is automatically created by the system.
+ fn thread_fn(&self) -> ThreadedFnReturn;
+}
+
+/// 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 `WakeThread`.
+///
+/// # Invariants
+///
+/// * We own an irq handler using `&self` as its private data.
+///
+/// # Examples
+///
+/// The following is an example of using `ThreadedRegistration`:
+///
+/// ```
+/// use kernel::prelude::*;
+/// use kernel::irq;
+/// use kernel::irq::Registration;
+/// use kernel::sync::Arc;
+/// use kernel::sync::lock::SpinLock;
+///
+/// // Declare a struct that will be passed in when the interrupt fires. The u32
+/// // merely serves as an example of some internal data.
+/// struct Data(u32);
+///
+/// // [`handle_irq`] returns &self. This example illustrates interior
+/// // mutability can be used when share the data between process context and IRQ
+/// // context.
+/// //
+/// // Ideally, this example would be using a version of SpinLock that is aware
+/// // of `spin_lock_irqsave` and `spin_lock_irqrestore`, but that is not yet
+/// // implemented.
+///
+/// type Handler = SpinLock<Data>;
+///
+/// impl kernel::irq::Handler for Handler {
+/// // This is executing in IRQ context in some CPU. Other CPUs can still
+/// // try to access to data.
+/// fn handle_irq(&self) -> irq::ThreadedIrqReturn {
+/// // We now have exclusive access to the data by locking the SpinLock.
+/// let mut handler = self.lock();
+/// handler.0 += 1;
+///
+/// // By returning `WakeThread`, we indicate to the system that the
+/// // thread function should be called. Otherwise, return
+/// // ThreadedIrqReturn::Handled.
+/// ThreadedIrqReturn::WakeThread
+/// }
+///
+/// // This will run (in a separate kthread) iff `handle_irq` returns
+/// // `WakeThread`.
+/// fn thread_fn(&self) -> irq::ThreadedFnReturn {
+/// // We now have exclusive access to the data by locking the SpinLock.
+/// let mut handler = self.lock();
+/// handler.0 += 1;
+/// }
+///
+/// // This is running in process context.
+/// fn register_irq(irq: u32, handler: Handler) -> Result<irq::Registration<Handler>> {
+/// let registration = ThreadedRegistration::register(irq, irq::flags::SHARED, "my-device", handler)?;
+///
+/// // You can have as many references to the registration as you want, so
+/// // multiple parts of the driver can access it.
+/// let registration = Arc::pin_init(registration)?;
+///
+/// // The handler may be called immediately after the function above
+/// // returns, possibly in a different CPU.
+///
+/// // The data can be accessed from the process context too.
+/// registration.handler().lock().0 = 42;
+///
+/// Ok(registration)
+/// }
+/// }
+///
+/// # Ok::<(), Error>(())
+///```
+#[pin_data(PinnedDrop)]
+pub struct ThreadedRegistration<T: ThreadedHandler> {
+ irq: u32,
+ #[pin]
+ handler: Opaque<T>,
+}
+
+impl<T: ThreadedHandler> ThreadedRegistration<T> {
+ /// Registers the IRQ handler with the system for the given IRQ number. The
+ /// handler must be able to be called as soon as this function returns.
+ pub fn register(
+ irq: u32,
+ flags: Flags,
+ name: &'static CStr,
+ handler: T,
+ ) -> impl PinInit<Self, Error> {
+ try_pin_init!(Self {
+ irq,
+ handler: Opaque::new(handler)
+ })
+ .pin_chain(move |slot| {
+ // SAFETY:
+ // - `handler` points to a valid function defined below.
+ // - only valid flags can be constructed using the `flags` module.
+ // - `devname` is a nul-terminated string with a 'static lifetime.
+ // - `ptr` is a cookie used to identify the handler. The same cookie is
+ // passed back when the system calls the handler.
+ to_result(unsafe {
+ bindings::request_threaded_irq(
+ irq,
+ Some(handle_threaded_irq_callback::<T>),
+ Some(thread_fn_callback::<T>),
+ flags.0,
+ name.as_char_ptr(),
+ &*slot as *const _ as *mut core::ffi::c_void,
+ )
+ })?;
+
+ Ok(())
+ })
+ }
+
+ /// Returns a reference to the handler that was registered with the system.
+ pub fn handler(&self) -> &T {
+ // SAFETY: `handler` is initialized in `register`.
+ unsafe { &*self.handler.get() }
+ }
+}
+
+#[pinned_drop]
+impl<T: ThreadedHandler> PinnedDrop for ThreadedRegistration<T> {
+ fn drop(self: Pin<&mut Self>) {
+ // SAFETY:
+ // - `self.irq` is the same as the one passed to `request_threaded_irq`.
+ // - `&self` was passed to `request_threaded_irq` as the cookie. It is
+ // guaranteed to be unique by the type system, since each call to
+ // `register` will return a different instance of
+ // `ThreadedRegistration`.
+ //
+ // Notice that this will block until all handlers finish executing, so,
+ // at no point will &self be invalid while the handler is running.
+ unsafe { bindings::free_irq(self.irq, &*self as *const _ as *mut core::ffi::c_void) };
+ }
+}
+
+unsafe extern "C" fn handle_irq_callback<T: Handler>(
+ _irq: i32,
+ ptr: *mut core::ffi::c_void,
+) -> core::ffi::c_uint {
+ let data = unsafe { &*(ptr as *const T) };
+ T::handle_irq(data) as _
+}
+
+unsafe extern "C" fn handle_threaded_irq_callback<T: ThreadedHandler>(
+ _irq: i32,
+ ptr: *mut core::ffi::c_void,
+) -> core::ffi::c_uint {
+ let data = unsafe { &*(ptr as *const T) };
+ T::handle_irq(data) as _
+}
+
+unsafe extern "C" fn thread_fn_callback<T: ThreadedHandler>(
+ _irq: i32,
+ ptr: *mut core::ffi::c_void,
+) -> core::ffi::c_uint {
+ let data = unsafe { &*(ptr as *const T) };
+ T::thread_fn(data) as _
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 22a3bfa5a9e96a1dd9cf76bd34a8d992458870b4..0390bc0b114f60876414c82b5b8862401338d241 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -36,6 +36,7 @@
pub mod firmware;
pub mod init;
pub mod ioctl;
+pub mod irq;
#[cfg(CONFIG_KUNIT)]
pub mod kunit;
pub mod list;
---
base-commit: 33c255312660653cf54f8019896b5dca28e3c580
change-id: 20241023-topic-panthor-rs-request_irq-62008ccc82eb
Best regards,
--
Daniel Almeida <daniel.almeida@...labora.com>
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