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rust: pci: Allocate and manage PCI interrupt vectors

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Add support to PCI rust module to allocate, free and manage IRQ vectors.
Integrate with devres for managing the allocated resources.

Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
[ Add links in doc-comments; add missing invariant comment; re-format
  multiple safety requirements as list and fix missing backticks;
  refactor the example of alloc_irq_vectors() to compile. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Joel Fernandes
2025-10-08 15:07:26 -04:00
committed by Danilo Krummrich
parent 3a86608788
commit 340ccc9735
1 changed files with 201 additions and 13 deletions
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214
rust/kernel/pci.rs
View File

@@ -6,8 +6,9 @@
use crate::{
bindings, container_of, device,
device::Bound,
device_id::{RawDeviceId, RawDeviceIdIndex},
devres::Devres,
devres::{self, Devres},
driver,
error::{from_result, to_result, Result},
io::{Io, IoRaw},
@@ -19,7 +20,7 @@ use crate::{
};
use core::{
marker::PhantomData,
ops::Deref,
ops::{Deref, RangeInclusive},
ptr::{addr_of_mut, NonNull},
};
use kernel::prelude::*;
@@ -28,6 +29,58 @@ mod id;
pub use self::id::{Class, ClassMask, Vendor};
/// IRQ type flags for PCI interrupt allocation.
#[derive(Debug, Clone, Copy)]
pub enum IrqType {
/// INTx interrupts.
Intx,
/// Message Signaled Interrupts (MSI).
Msi,
/// Extended Message Signaled Interrupts (MSI-X).
MsiX,
}
impl IrqType {
/// Convert to the corresponding kernel flags.
const fn as_raw(self) -> u32 {
match self {
IrqType::Intx => bindings::PCI_IRQ_INTX,
IrqType::Msi => bindings::PCI_IRQ_MSI,
IrqType::MsiX => bindings::PCI_IRQ_MSIX,
}
}
}
/// Set of IRQ types that can be used for PCI interrupt allocation.
#[derive(Debug, Clone, Copy, Default)]
pub struct IrqTypes(u32);
impl IrqTypes {
/// Create a set containing all IRQ types (MSI-X, MSI, and Legacy).
pub const fn all() -> Self {
Self(bindings::PCI_IRQ_ALL_TYPES)
}
/// Build a set of IRQ types.
///
/// # Examples
///
/// ```ignore
/// // Create a set with only MSI and MSI-X (no legacy interrupts).
/// let msi_only = IrqTypes::default()
/// .with(IrqType::Msi)
/// .with(IrqType::MsiX);
/// ```
pub const fn with(self, irq_type: IrqType) -> Self {
Self(self.0 | irq_type.as_raw())
}
/// Get the raw flags value.
const fn as_raw(self) -> u32 {
self.0
}
}
/// An adapter for the registration of PCI drivers.
pub struct Adapter<T: Driver>(T);
@@ -516,6 +569,92 @@ impl Device {
}
}
/// Represents an allocated IRQ vector for a specific PCI device.
///
/// This type ties an IRQ vector to the device it was allocated for,
/// ensuring the vector is only used with the correct device.
#[derive(Clone, Copy)]
pub struct IrqVector<'a> {
dev: &'a Device<Bound>,
index: u32,
}
impl<'a> IrqVector<'a> {
/// Creates a new [`IrqVector`] for the given device and index.
///
/// # Safety
///
/// - `index` must be a valid IRQ vector index for `dev`.
/// - `dev` must point to a [`Device`] that has successfully allocated IRQ vectors.
unsafe fn new(dev: &'a Device<Bound>, index: u32) -> Self {
Self { dev, index }
}
/// Returns the raw vector index.
fn index(&self) -> u32 {
self.index
}
}
/// Represents an IRQ vector allocation for a PCI device.
///
/// This type ensures that IRQ vectors are properly allocated and freed by
/// tying the allocation to the lifetime of this registration object.
///
/// # Invariants
///
/// The [`Device`] has successfully allocated IRQ vectors.
struct IrqVectorRegistration {
dev: ARef<Device>,
}
impl IrqVectorRegistration {
/// Allocate and register IRQ vectors for the given PCI device.
///
/// Allocates IRQ vectors and registers them with devres for automatic cleanup.
/// Returns a range of valid IRQ vectors.
fn register<'a>(
dev: &'a Device<Bound>,
min_vecs: u32,
max_vecs: u32,
irq_types: IrqTypes,
) -> Result<RangeInclusive<IrqVector<'a>>> {
// SAFETY:
// - `dev.as_raw()` is guaranteed to be a valid pointer to a `struct pci_dev`
// by the type invariant of `Device`.
// - `pci_alloc_irq_vectors` internally validates all other parameters
// and returns error codes.
let ret = unsafe {
bindings::pci_alloc_irq_vectors(dev.as_raw(), min_vecs, max_vecs, irq_types.as_raw())
};
to_result(ret)?;
let count = ret as u32;
// SAFETY:
// - `pci_alloc_irq_vectors` returns the number of allocated vectors on success.
// - Vectors are 0-based, so valid indices are [0, count-1].
// - `pci_alloc_irq_vectors` guarantees `count >= min_vecs > 0`, so both `0` and
// `count - 1` are valid IRQ vector indices for `dev`.
let range = unsafe { IrqVector::new(dev, 0)..=IrqVector::new(dev, count - 1) };
// INVARIANT: The IRQ vector allocation for `dev` above was successful.
let irq_vecs = Self { dev: dev.into() };
devres::register(dev.as_ref(), irq_vecs, GFP_KERNEL)?;
Ok(range)
}
}
impl Drop for IrqVectorRegistration {
fn drop(&mut self) {
// SAFETY:
// - By the type invariant, `self.dev.as_raw()` is a valid pointer to a `struct pci_dev`.
// - `self.dev` has successfully allocated IRQ vectors.
unsafe { bindings::pci_free_irq_vectors(self.dev.as_raw()) };
}
}
impl Device<device::Bound> {
/// Mapps an entire PCI-BAR after performing a region-request on it. I/O operation bound checks
/// can be performed on compile time for offsets (plus the requested type size) < SIZE.
@@ -536,10 +675,15 @@ impl Device<device::Bound> {
self.iomap_region_sized::<0>(bar, name)
}
/// Returns an [`IrqRequest`] for the IRQ vector at the given index, if any.
pub fn irq_vector(&self, index: u32) -> Result<IrqRequest<'_>> {
/// Returns an [`IrqRequest`] for the given IRQ vector.
pub fn irq_vector(&self, vector: IrqVector<'_>) -> Result<IrqRequest<'_>> {
// Verify that the vector belongs to this device.
if !core::ptr::eq(vector.dev.as_raw(), self.as_raw()) {
return Err(EINVAL);
}
// SAFETY: `self.as_raw` returns a valid pointer to a `struct pci_dev`.
let irq = unsafe { crate::bindings::pci_irq_vector(self.as_raw(), index) };
let irq = unsafe { crate::bindings::pci_irq_vector(self.as_raw(), vector.index()) };
if irq < 0 {
return Err(crate::error::Error::from_errno(irq));
}
@@ -547,35 +691,79 @@ impl Device<device::Bound> {
Ok(unsafe { IrqRequest::new(self.as_ref(), irq as u32) })
}
/// Returns a [`kernel::irq::Registration`] for the IRQ vector at the given
/// index.
/// Returns a [`kernel::irq::Registration`] for the given IRQ vector.
pub fn request_irq<'a, T: crate::irq::Handler + 'static>(
&'a self,
index: u32,
vector: IrqVector<'_>,
flags: irq::Flags,
name: &'static CStr,
handler: impl PinInit<T, Error> + 'a,
) -> Result<impl PinInit<irq::Registration<T>, Error> + 'a> {
let request = self.irq_vector(index)?;
let request = self.irq_vector(vector)?;
Ok(irq::Registration::<T>::new(request, flags, name, handler))
}
/// Returns a [`kernel::irq::ThreadedRegistration`] for the IRQ vector at
/// the given index.
/// Returns a [`kernel::irq::ThreadedRegistration`] for the given IRQ vector.
pub fn request_threaded_irq<'a, T: crate::irq::ThreadedHandler + 'static>(
&'a self,
index: u32,
vector: IrqVector<'_>,
flags: irq::Flags,
name: &'static CStr,
handler: impl PinInit<T, Error> + 'a,
) -> Result<impl PinInit<irq::ThreadedRegistration<T>, Error> + 'a> {
let request = self.irq_vector(index)?;
let request = self.irq_vector(vector)?;
Ok(irq::ThreadedRegistration::<T>::new(
request, flags, name, handler,
))
}
/// Allocate IRQ vectors for this PCI device with automatic cleanup.
///
/// Allocates between `min_vecs` and `max_vecs` interrupt vectors for the device.
/// The allocation will use MSI-X, MSI, or legacy interrupts based on the `irq_types`
/// parameter and hardware capabilities. When multiple types are specified, the kernel
/// will try them in order of preference: MSI-X first, then MSI, then legacy interrupts.
///
/// The allocated vectors are automatically freed when the device is unbound, using the
/// devres (device resource management) system.
///
/// # Arguments
///
/// * `min_vecs` - Minimum number of vectors required.
/// * `max_vecs` - Maximum number of vectors to allocate.
/// * `irq_types` - Types of interrupts that can be used.
///
/// # Returns
///
/// Returns a range of IRQ vectors that were successfully allocated, or an error if the
/// allocation fails or cannot meet the minimum requirement.
///
/// # Examples
///
/// ```
/// # use kernel::{ device::Bound, pci};
/// # fn no_run(dev: &pci::Device<Bound>) -> Result {
/// // Allocate using any available interrupt type in the order mentioned above.
/// let vectors = dev.alloc_irq_vectors(1, 32, pci::IrqTypes::all())?;
///
/// // Allocate MSI or MSI-X only (no legacy interrupts).
/// let msi_only = pci::IrqTypes::default()
/// .with(pci::IrqType::Msi)
/// .with(pci::IrqType::MsiX);
/// let vectors = dev.alloc_irq_vectors(4, 16, msi_only)?;
/// # Ok(())
/// # }
/// ```
pub fn alloc_irq_vectors(
&self,
min_vecs: u32,
max_vecs: u32,
irq_types: IrqTypes,
) -> Result<RangeInclusive<IrqVector<'_>>> {
IrqVectorRegistration::register(self, min_vecs, max_vecs, irq_types)
}
}
impl Device<device::Core> {