From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f44.google.com (mail-wr1-f44.google.com [209.85.221.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D666135950; Thu, 23 Jan 2025 16:00:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.44 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737648016; cv=none; b=N9mf08MBj4u8Vua5mmKvsU0a2qRfd8C4Gv3PF0Y2sPgPcOd5EWfSRqXcWomH/sV3OeW89IgvaP0JVuecFkOYu1rZqFWHQFNwZdCQ9Zytwxrpf/Cjj2/vrCIPoezXb/uZGMrwaHcNEcoek4ygFZRwawRhchLwYGRP8TCptsOSkXQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737648016; c=relaxed/simple; bh=ilVO+eLgnH1HXpNHlu5Js9orudEww4dv9hG2pvdrzic=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sz0t72ZH2aIIM67F8HruK6VKzgY5FM7h26H8kt055IwVn/cqrshp9aD5LFCrQdvGu1ZwtcS1eZqEjLCuWwg31kPGRYCGuhBDU8Wz8avvA0ZIYWYmvuEDfqD9sRRHLht58YUq+Cs3z24xBxrcAVxDFdyjlFlHAovi+RoOfMD78IE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=j5UlBqxb; arc=none smtp.client-ip=209.85.221.44 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="j5UlBqxb" Received: by mail-wr1-f44.google.com with SMTP id ffacd0b85a97d-385eed29d17so602796f8f.0; Thu, 23 Jan 2025 08:00:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1737648012; x=1738252812; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=gEIda5CW+IGUa1pNICbiRFIAl5pcyLiFFcWG9iJhQlI=; b=j5UlBqxbklok1RbXZYb2h/sK6Xe91rD9rBHFJxbZZc3jS+dUkf5fnGaqD7u2mz3HrJ mf59/YimbRsMsCXuUzosWMEj/LvwS3EHahnVhojcBiDRTIRqCrVPLl38YzVA+m4T3rgk O5eUnRW1gzb3ziVFuGrWTPGOxzpTrcqgIskVnn4gL+0Lnh0f+VGTnfHfiYwqgcC7pElN mWWVgqGEj9H4v8uAr3piJXViR91DURdpoq8WvuRG4ushgL2sv/aaUjAD8Z3/9cKNklMv 0vP8mlI7wwszo5Fu9NTdzX/f4fU9uI/OsgIa0TRvniE2yBhSz0WVDvPP4wiOd4MKLrDU G9+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1737648012; x=1738252812; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=gEIda5CW+IGUa1pNICbiRFIAl5pcyLiFFcWG9iJhQlI=; b=Z7IQ912VyYtl62SARaT5H7dDvyl1162PlUjJJugRLbS60cni92tXH95NH3BnTTrFKv MzbkRKRDaSgV5NEpoDRgf5oTQN6PuYhu+zRg+EQBljDX68x8S5EdND+881TLQXb/fZIj xm/6aT4BbUzhLhohXVsWQVfTuHb6gE9njZ4+z036CqebTGHZ3Zrg3WiCczNIE/r7GN45 N7AMD4d4wl2Ov6DMkWy4Wl8XI3UQNmZQROwCxhnhL2hEpp8lUyvLa6/YunhLH5Tmon8t iwLLKKu8JdpeM/2/Im9p51nT0J+V9Ry0308R/MiS/6z2P34eqqTVkr3f4arE1+v3RbEJ ymOw== X-Forwarded-Encrypted: i=1; AJvYcCWeW9QG9SPcapS6pXfQC9fglGw7jmnA2iMNqaYjv/hOTtLXGVE1AzY1sIriqHZND83XbnPl/OEf0Npo8ec=@vger.kernel.org X-Gm-Message-State: AOJu0Yy8RuZoMY7F1ghCkHPOwYKXAV2gzbR/w1ullWN2s/AbKwrZTcnL c6tdL7zuvxtaaCP6pMOE6F7/0T9AFwfhkj7B5BKcMsHxLLqQ2NN8 X-Gm-Gg: ASbGncvAnApe3rTr48pf/XRuhfWRWqq+oaBU2M05i4xwK1S0fmjl+2Ikt6G80CGbJ7x oAy/ZPVPvI3xqPd/EaCRNF1/RKfLC7gAgkzqnYhOsbP4jqIX0OPrZYnZRS0q8IQgJRnbVtB08Bx Tuj46urL3eydeKO0iZ8MRRkcNc2C479+x+DY6n1MZpKDCpLvnD4EX6Mcr23R2osM3JO+uABrWrz Dv9aDtEe7CHX9CBzzV+qXIjqY2nAfmgReN0E85xkpiuzTauP/mUalOBbiGQOHyA2G/fwupn9Td9 uY5p/Jqc6AVukLk/0g== X-Google-Smtp-Source: AGHT+IFjHYTCqn/dat5g6FFCcWZzt5DkbrysLnQ0tKN6aiwybbbZdY9tzTIl6LKcmhV7IoFnF3tc2A== X-Received: by 2002:a5d:64e9:0:b0:386:2ebe:7ae2 with SMTP id ffacd0b85a97d-38bf57b8aa7mr24239271f8f.45.1737648011652; Thu, 23 Jan 2025 08:00:11 -0800 (PST) Received: from ?IPV6:2001:871:22a:8634::1ad1? ([2001:871:22a:8634::1ad1]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38c2a189283sm63234f8f.59.2025.01.23.08.00.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Jan 2025 08:00:11 -0800 (PST) Message-ID: <8a2bac6e-1989-41d8-a5f6-3bb518a9f139@gmail.com> Date: Thu, 23 Jan 2025 17:00:09 +0100 Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] rust: irq: add support for request_irq() To: Daniel Almeida , ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@kernel.org, tmgross@umich.edu Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Alice Ryhl References: <20250122163932.46697-1-daniel.almeida@collabora.com> Content-Language: en-US From: Christian Schrefl In-Reply-To: <20250122163932.46697-1-daniel.almeida@collabora.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 22.01.25 5:39 PM, Daniel Almeida wrote: > Add support for registering IRQ handlers in Rust. > > IRQ handlers are extensively used in drivers when some peripheral wants to > obtain the CPU attention. Registering a handler will make the system invoke the > passed-in function whenever the chosen IRQ line is triggered. > > Both regular and threaded IRQ handlers are supported through a Handler (or > ThreadedHandler) trait that is meant to be implemented by a type that: > > a) provides a function to be run by the system when the IRQ fires and, > > b) holds the shared data (i.e.: `T`) between process and IRQ contexts. > > The requirement that T is Sync derives from the fact that handlers might run > concurrently with other processes executing the same driver, creating the > potential for data races. > > Ideally, some interior mutability must be in place if T is to be mutated. This > should usually be done through the in-flight SpinLockIrq type. > > Co-developed-by: Alice Ryhl > Signed-off-by: Alice Ryhl > Signed-off-by: Daniel Almeida It would be nice it you included a second patch that adds the ability to get the irq number from a platform device, it should be pretty simple. Of course this can also just be done separately. Otherwise this looks pretty good, a few small comments below. > --- > > Changes from v1: > > - Added Co-developed-by tag to account for the work that Alice did in order to > figure out how to do this without Opaque (Thanks!) > - Removed Opaque in favor of plain T > - Fixed the examples > - Made sure that the invariants sections are the last entry in the docs > - Switched to slot.cast() where applicable, > - Mentioned in the safety comments that we require that T: Sync, > - Removed ThreadedFnReturn in favor of IrqReturn, > - Improved the commit message > > Link to v1: https://lore.kernel.org/rust-for-linux/20241024-topic-panthor-rs-request_irq-v1-1-7cbc51c182ca@collabora.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 | 517 ++++++++++++++++++++++++++++++++ > rust/kernel/lib.rs | 1 + > 6 files changed, 535 insertions(+) > create mode 100644 rust/helpers/irq.c > create mode 100644 rust/kernel/irq.rs > create mode 100644 rust/kernel/irq/request.rs > > diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h > index 5c4dfe22f41a..0331c6273def 100644 > --- a/rust/bindings/bindings_helper.h > +++ b/rust/bindings/bindings_helper.h > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > #include > #include > #include > diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c > index dcf827a61b52..bfc499d7f4c1 100644 > --- a/rust/helpers/helpers.c > +++ b/rust/helpers/helpers.c > @@ -13,6 +13,7 @@ > #include "build_bug.c" > #include "cred.c" > #include "err.c" > +#include "irq.c" > #include "fs.c" > #include "jump_label.c" > #include "kunit.c" > diff --git a/rust/helpers/irq.c b/rust/helpers/irq.c > new file mode 100644 > index 000000000000..1faca428e2c0 > --- /dev/null > +++ b/rust/helpers/irq.c > @@ -0,0 +1,9 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include > + > +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 000000000000..3ab83c5bdb83 > --- /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 000000000000..61e7d4a8f555 > --- /dev/null > +++ b/rust/kernel/irq/request.rs > @@ -0,0 +1,517 @@ > +// SPDX-License-Identifier: GPL-2.0 > +// SPDX-FileCopyrightText: Copyright 2025 Collabora ltd. > + > +//! IRQ allocation and handling > + > +use core::marker::PhantomPinned; > +use core::ptr::addr_of_mut; > + > +use init::pin_init_from_closure; > + > +use crate::error::to_result; > +use crate::prelude::*; > +use crate::str::CStr; > + > +/// 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 { Maybe move flags into a separate file? You even have a directory for irq. > + 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 or a ThreadedIrqHandler. > +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. > +/// > +/// # Examples > +/// > +/// The following is an example of using `Registration`: > +/// > +/// ``` > +/// use kernel::prelude::*; > +/// use kernel::irq::request::flags; > +/// use kernel::irq::request::Registration; > +/// use kernel::irq::request::IrqReturn; > +/// use kernel::sync::Arc; > +/// use kernel::sync::SpinLock; > +/// use kernel::c_str; > +/// use kernel::alloc::flags::GFP_KERNEL; > +/// > +/// // 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(SpinLock); > +/// > +/// // [`handle_irq`] takes &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 = Data; > +/// > +/// impl kernel::irq::request::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) -> IrqReturn { > +/// // We now have exclusive access to the data by locking the SpinLock. > +/// let mut data = self.0.lock(); > +/// *data += 1; > +/// > +/// IrqReturn::Handled > +/// } > +/// } > +/// > +/// // This is running in process context. > +/// fn register_irq(irq: u32, handler: Handler) -> Result>> { > +/// let registration = Registration::register(irq, flags::SHARED, c_str!("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, GFP_KERNEL)?; > +/// > +/// // 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. > +/// let mut data = registration.handler().0.lock(); > +/// *data = 42; > +/// } > +/// > +/// Ok(registration) > +/// } > +/// > +/// # Ok::<(), Error>(()) > +///``` > +/// > +/// # Invariants > +/// > +/// * We own an irq handler using `&self` as its private data. > +/// > +#[pin_data(PinnedDrop)] > +pub struct Registration { > + irq: u32, > + #[pin] > + handler: T, > + #[pin] > + /// Pinned because we need address stability so that we can pass a pointer > + /// to the callback. > + _pin: PhantomPinned, > +} > + > +impl Registration { > + /// 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 { > + let closure = move |slot: *mut Self| { > + // SAFETY: The slot passed to pin initializer is valid for writing. > + unsafe { > + slot.write(Self { > + irq, > + handler, > + _pin: PhantomPinned, > + }) > + }; > + > + // 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. > + let res = to_result(unsafe { > + bindings::request_irq( > + irq, > + Some(handle_irq_callback::), > + flags.0, > + name.as_char_ptr(), > + &*slot as *const _ as *mut core::ffi::c_void, > + ) > + }); > + > + if res.is_err() { > + // SAFETY: We are returning an error, so we can destroy the slot. > + unsafe { core::ptr::drop_in_place(addr_of_mut!((*slot).handler)) }; > + } > + > + res > + }; > + > + // SAFETY: > + // - if this returns Ok, then every field of `slot` is fully > + // initialized. > + // - if this returns an error, then the slot does not need to remain > + // valid. > + unsafe { pin_init_from_closure(closure) } > + } > + > + /// Returns a reference to the handler that was registered with the system. > + pub fn handler(&self) -> &T { > + // SAFETY: `handler` is initialized in `register`, and we require that > + // T: Sync. > + &self.handler > + } > +} > + > +#[pinned_drop] > +impl PinnedDrop for Registration { > + 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, > + // i.e.: at no point will &self be invalid while the handler is running. > + unsafe { bindings::free_irq(self.irq, &*self as *const Self 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 _, > +} > + > +/// 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) -> IrqReturn; > +} > + > +/// 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`. > +/// > +/// # Examples > +/// > +/// The following is an example of using `ThreadedRegistration`: > +/// > +/// ``` > +/// use kernel::prelude::*; > +/// use kernel::irq::request::flags; > +/// use kernel::irq::request::ThreadedIrqReturn; > +/// use kernel::irq::request::ThreadedRegistration; > +/// use kernel::irq::request::IrqReturn; > +/// use kernel::sync::Arc; > +/// use kernel::sync::SpinLock; > +/// use kernel::alloc::flags::GFP_KERNEL; > +/// use kernel::c_str; > +/// > +/// // 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(SpinLock); > +/// > +/// // [`handle_irq`] takes &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 = Data; > +/// > +/// impl kernel::irq::request::ThreadedHandler for Handler { > +/// // This is executing in IRQ context in some CPU. Other CPUs can still > +/// // try to access to data. > +/// fn handle_irq(&self) -> ThreadedIrqReturn { > +/// // We now have exclusive access to the data by locking the SpinLock. > +/// let mut data = self.0.lock(); > +/// *data += 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 typo iff > +/// // `WakeThread`. > +/// fn thread_fn(&self) -> IrqReturn { > +/// // We now have exclusive access to the data by locking the SpinLock. > +/// let mut data = self.0.lock(); > +/// *data += 1; > +/// > +/// IrqReturn::Handled > +/// } > +/// } > +/// > +/// // This is running in process context. > +/// fn register_threaded_irq(irq: u32, handler: Handler) -> Result>> { > +/// let registration = ThreadedRegistration::register(irq, flags::SHARED, c_str!("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, GFP_KERNEL)?; You can use Arc::new instead, since you don't need pin_init. > +/// > +/// // 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. > +/// let mut data = registration.handler().0.lock(); > +/// *data = 42; > +/// } > +/// > +/// Ok(registration) > +/// } > +/// > +/// > +/// # Ok::<(), Error>(()) > +///``` > +/// > +/// # Invariants > +/// > +/// * We own an irq handler using `&self` as its private data. > +/// > +#[pin_data(PinnedDrop)] > +pub struct ThreadedRegistration { > + irq: u32, > + #[pin] > + handler: T, > + #[pin] > + /// Pinned because we need address stability so that we can pass a pointer > + /// to the callback. > + _pin: PhantomPinned, > +} > + > +impl ThreadedRegistration { > + /// 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 { > + let closure = move |slot: *mut Self| { > + // SAFETY: The slot passed to pin initializer is valid for writing. > + unsafe { > + slot.write(Self { > + irq, > + handler, > + _pin: PhantomPinned, > + }) > + }; > + > + // 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. > + let res = to_result(unsafe { > + bindings::request_threaded_irq( > + irq, > + Some(handle_threaded_irq_callback::), > + Some(thread_fn_callback::), > + flags.0, > + name.as_char_ptr(), > + slot.cast(), > + ) > + }); > + > + if res.is_err() { > + // SAFETY: We are returning an error, so we can destroy the slot. > + unsafe { core::ptr::drop_in_place(addr_of_mut!((*slot).handler)) }; > + } > + > + res > + }; > + > + // SAFETY: > + // - if this returns Ok(()), then every field of `slot` is fully > + // initialized. > + // - if this returns an error, then the slot does not need to remain > + // valid. > + unsafe { pin_init_from_closure(closure) } > + } > + > + /// Returns a reference to the handler that was registered with the system. > + pub fn handler(&self) -> &T { > + // SAFETY: `handler` is initialized in `register`, and we require that > + // T: Sync. > + &self.handler > + } > +} > + > +#[pinned_drop] > +impl PinnedDrop for ThreadedRegistration { > + 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 Self as *mut core::ffi::c_void) }; > + } > +} > + > +/// # Safety > +/// > +/// This function should be only used as the callback in `request_irq`. > +unsafe extern "C" fn handle_irq_callback( > + _irq: i32, > + ptr: *mut core::ffi::c_void, > +) -> core::ffi::c_uint { > + // SAFETY: `ptr` is a poinhandle_threaded_irq_callbackter to T set in `Registration::new` > + let data = unsafe { &*(ptr as *const T) }; > + T::handle_irq(data) as _ > + Can `handle_irq_callback` and `handle_threaded_irq_callback` be shared somehow? Otherwise maybe define them locally in the calling function, since nothing else should ever use them, so we might as well restrict their scope. > + > +/// # Safety > +/// > +/// This function should be only used as the callback in `request_threaded_irq`. > +unsafe extern "C" fn handle_threaded_irq_callback( > + _irq: i32, > + ptr: *mut core::ffi::c_void, > +) -> core::ffi::c_uint { > + // SAFETY: `ptr` is a pointer to T set in `ThreadedRegistration::new` > + let data = unsafe { &*(ptr as *const T) }; > + T::handle_irq(data) as _ > +} > + > +/// # Safety > +/// > +/// This function should be only used as the callback in `request_threaded_irq`. > +unsafe extern "C" fn thread_fn_callback( > + _irq: i32, > + ptr: *mut core::ffi::c_void, > +) -> core::ffi::c_uint { > + // SAFETY: `ptr` is a pointer to T set in `ThreadedRegistration::new` > + 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 e1065a7551a3..bba782e138c5 100644 > --- a/rust/kernel/lib.rs > +++ b/rust/kernel/lib.rs > @@ -41,6 +41,7 @@ > pub mod fs; > pub mod init; > pub mod ioctl; > +pub mod irq; > pub mod jump_label; > #[cfg(CONFIG_KUNIT)] > pub mod kunit;