[PATCH v6 09/16] rust: pci: add basic PCI device / driver abstractions

Danilo Krummrich
2024-12-12T16:35:58Z

Implement the basic PCI abstractions required to write a basic PCI
driver. This includes the following data structures:

The `pci::Driver` trait represents the interface to the driver and
provides `pci::Driver::probe` for the driver to implement.

The `pci::Device` abstraction represents a `struct pci_dev` and provides
abstractions for common functions, such as `pci::Device::set_master`.

In order to provide the PCI specific parts to a generic
`driver::Registration` the `driver::RegistrationOps` trait is implemented
by `pci::Adapter`.

`pci::DeviceId` implements PCI device IDs based on the generic
`device_id::RawDevceId` abstraction.

Co-developed-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
MAINTAINERS | 1 +
rust/bindings/bindings_helper.h | 1 +
rust/helpers/helpers.c | 1 +
rust/helpers/pci.c | 18 ++
rust/kernel/lib.rs | 2 +
rust/kernel/pci.rs | 298 ++++++++++++++++++++++++++++++++
6 files changed, 321 insertions(+)
create mode 100644 rust/helpers/pci.c
create mode 100644 rust/kernel/pci.rs

diff --git a/MAINTAINERS b/MAINTAINERS
index 096a7d9ee966..e143969265aa 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18102,6 +18102,7 @@ F: include/asm-generic/pci*
F: include/linux/of_pci.h
F: include/linux/pci*
F: include/uapi/linux/pci*
+F: rust/kernel/pci.rs

PCIE BANDWIDTH CONTROLLER
M: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 5c4dfe22f41a..6d7a68e2ecb7 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -20,6 +20,7 @@
#include <linux/jump_label.h>
#include <linux/mdio.h>
#include <linux/miscdevice.h>
+#include <linux/pci.h>
#include <linux/phy.h>
#include <linux/pid_namespace.h>
#include <linux/poll.h>
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index a3b52aa021de..3fda33cd42d4 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -20,6 +20,7 @@
#include "kunit.c"
#include "mutex.c"
#include "page.c"
+#include "pci.c"
#include "pid_namespace.c"
#include "rbtree.c"
#include "rcu.c"
diff --git a/rust/helpers/pci.c b/rust/helpers/pci.c
new file mode 100644
index 000000000000..8ba22f911459
--- /dev/null
+++ b/rust/helpers/pci.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pci.h>
+
+void rust_helper_pci_set_drvdata(struct pci_dev *pdev, void *data)
+{
+ pci_set_drvdata(pdev, data);
+}
+
+void *rust_helper_pci_get_drvdata(struct pci_dev *pdev)
+{
+ return pci_get_drvdata(pdev);
+}
+
+resource_size_t rust_helper_pci_resource_len(struct pci_dev *pdev, int bar)
+{
+ return pci_resource_len(pdev, bar);
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 2b61bf99d1ee..1dc7eda6b480 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -82,6 +82,8 @@
pub use bindings;
pub mod io;
pub use macros;
+#[cfg(all(CONFIG_PCI, CONFIG_PCI_MSI))]
+pub mod pci;
pub use uapi;

#[doc(hidden)]
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
new file mode 100644
index 000000000000..238eed06f388
--- /dev/null
+++ b/rust/kernel/pci.rs
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Abstractions for the PCI bus.
+//!
+//! C header: [`include/linux/pci.h`](srctree/include/linux/pci.h)
+
+use crate::{
+ bindings, container_of, device,
+ device_id::RawDeviceId,
+ driver,
+ error::{to_result, Result},
+ str::CStr,
+ types::{ARef, ForeignOwnable, Opaque},
+ ThisModule,
+};
+use core::{ops::Deref, ptr::addr_of_mut};
+use kernel::prelude::*;
+
+/// An adapter for the registration of PCI drivers.
+pub struct Adapter<T: Driver>(T);
+
+impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+ type RegType = bindings::pci_driver;
+
+ fn register(
+ pdrv: &Opaque<Self::RegType>,
+ name: &'static CStr,
+ module: &'static ThisModule,
+ ) -> Result {
+ // SAFETY: It's safe to set the fields of `struct pci_driver` on initialization.
+ unsafe {
+ (*pdrv.get()).name = name.as_char_ptr();
+ (*pdrv.get()).probe = Some(Self::probe_callback);
+ (*pdrv.get()).remove = Some(Self::remove_callback);
+ (*pdrv.get()).id_table = T::ID_TABLE.as_ptr();
+ }
+
+ // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
+ to_result(unsafe {
+ bindings::__pci_register_driver(pdrv.get(), module.0, name.as_char_ptr())
+ })
+ }
+
+ fn unregister(pdrv: &Opaque<Self::RegType>) {
+ // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
+ unsafe { bindings::pci_unregister_driver(pdrv.get()) }
+ }
+}
+
+impl<T: Driver + 'static> Adapter<T> {
+ extern "C" fn probe_callback(
+ pdev: *mut bindings::pci_dev,
+ id: *const bindings::pci_device_id,
+ ) -> core::ffi::c_int {
+ // SAFETY: The PCI bus only ever calls the probe callback with a valid pointer to a
+ // `struct pci_dev`.
+ let dev = unsafe { device::Device::get_device(addr_of_mut!((*pdev).dev)) };
+ // SAFETY: `dev` is guaranteed to be embedded in a valid `struct pci_dev` by the call
+ // above.
+ let mut pdev = unsafe { Device::from_dev(dev) };
+
+ // SAFETY: `DeviceId` is a `#[repr(transparent)` wrapper of `struct pci_device_id` and
+ // does not add additional invariants, so it's safe to transmute.
+ let id = unsafe { &*id.cast::<DeviceId>() };
+ let info = T::ID_TABLE.info(id.index());
+
+ match T::probe(&mut pdev, info) {
+ Ok(data) => {
+ // Let the `struct pci_dev` own a reference of the driver's private data.
+ // SAFETY: By the type invariant `pdev.as_raw` returns a valid pointer to a
+ // `struct pci_dev`.
+ unsafe { bindings::pci_set_drvdata(pdev.as_raw(), data.into_foreign() as _) };
+ }
+ Err(err) => return Error::to_errno(err),
+ }
+
+ 0
+ }
+
+ extern "C" fn remove_callback(pdev: *mut bindings::pci_dev) {
+ // SAFETY: The PCI bus only ever calls the remove callback with a valid pointer to a
+ // `struct pci_dev`.
+ let ptr = unsafe { bindings::pci_get_drvdata(pdev) };
+
+ // SAFETY: `remove_callback` is only ever called after a successful call to
+ // `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized
+ // `KBox<T>` pointer created through `KBox::into_foreign`.
+ let _ = unsafe { KBox::<T>::from_foreign(ptr) };
+ }
+}
+
+/// Declares a kernel module that exposes a single PCI driver.
+///
+/// # Example
+///
+///```ignore
+/// kernel::module_pci_driver! {
+/// type: MyDriver,
+/// name: "Module name",
+/// author: "Author name",
+/// description: "Description",
+/// license: "GPL v2",
+/// }
+///```
+#[macro_export]
+macro_rules! module_pci_driver {
+($($f:tt)*) => {
+ $crate::module_driver!(<T>, $crate::pci::Adapter<T>, { $($f)* });
+};
+}
+
+/// Abstraction for bindings::pci_device_id.
+#[repr(transparent)]
+#[derive(Clone, Copy)]
+pub struct DeviceId(bindings::pci_device_id);
+
+impl DeviceId {
+ const PCI_ANY_ID: u32 = !0;
+
+ /// PCI_DEVICE macro.
+ pub const fn new(vendor: u32, device: u32) -> Self {
+ Self(bindings::pci_device_id {
+ vendor,
+ device,
+ subvendor: DeviceId::PCI_ANY_ID,
+ subdevice: DeviceId::PCI_ANY_ID,
+ class: 0,
+ class_mask: 0,
+ driver_data: 0,
+ override_only: 0,
+ })
+ }
+
+ /// PCI_DEVICE_CLASS macro.
+ pub const fn with_class(class: u32, class_mask: u32) -> Self {
+ Self(bindings::pci_device_id {
+ vendor: DeviceId::PCI_ANY_ID,
+ device: DeviceId::PCI_ANY_ID,
+ subvendor: DeviceId::PCI_ANY_ID,
+ subdevice: DeviceId::PCI_ANY_ID,
+ class,
+ class_mask,
+ driver_data: 0,
+ override_only: 0,
+ })
+ }
+}
+
+// Allow drivers R/O access to the fields of `pci_device_id`; should we prefer accessor functions
+// to void exposing C structure fields?
+impl Deref for DeviceId {
+ type Target = bindings::pci_device_id;
+
+ fn deref(&self) -> &Self::Target {
+ &self.0
+ }
+}
+
+// SAFETY:
+// * `DeviceId` is a `#[repr(transparent)` wrapper of `pci_device_id` and does not add
+// additional invariants, so it's safe to transmute to `RawType`.
+// * `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field.
+unsafe impl RawDeviceId for DeviceId {
+ type RawType = bindings::pci_device_id;
+
+ const DRIVER_DATA_OFFSET: usize = core::mem::offset_of!(bindings::pci_device_id, driver_data);
+
+ fn index(&self) -> usize {
+ self.driver_data as _
+ }
+}
+
+/// IdTable type for PCI
+pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;
+
+/// Create a PCI `IdTable` with its alias for modpost.
+#[macro_export]
+macro_rules! pci_device_table {
+ ($table_name:ident, $module_table_name:ident, $id_info_type: ty, $table_data: expr) => {
+ const $table_name: $crate::device_id::IdArray<
+ $crate::pci::DeviceId,
+ $id_info_type,
+ { $table_data.len() },
+ > = $crate::device_id::IdArray::new($table_data);
+
+ $crate::module_device_table!("pci", $module_table_name, $table_name);
+ };
+}
+
+/// The PCI driver trait.
+///
+/// # Example
+///
+///```
+/// # use kernel::{bindings, pci};
+///
+/// struct MyDriver;
+///
+/// kernel::pci_device_table!(
+/// PCI_TABLE,
+/// MODULE_PCI_TABLE,
+/// <MyDriver as pci::Driver>::IdInfo,
+/// [
+/// (pci::DeviceId::new(bindings::PCI_VENDOR_ID_REDHAT, bindings::PCI_ANY_ID as u32), ())
+/// ]
+/// );
+///
+/// impl pci::Driver for MyDriver {
+/// type IdInfo = ();
+/// const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE;
+///
+/// fn probe(
+/// _pdev: &mut pci::Device,
+/// _id_info: &Self::IdInfo,
+/// ) -> Result<Pin<KBox<Self>>> {
+/// Err(ENODEV)
+/// }
+/// }
+///```
+/// Drivers must implement this trait in order to get a PCI driver registered. Please refer to the
+/// `Adapter` documentation for an example.
+pub trait Driver {
+ /// The type holding information about each device id supported by the driver.
+ ///
+ /// TODO: Use associated_type_defaults once stabilized:
+ ///
+ /// type IdInfo: 'static = ();
+ type IdInfo: 'static;
+
+ /// The table of device ids supported by the driver.
+ const ID_TABLE: IdTable<Self::IdInfo>;
+
+ /// PCI driver probe.
+ ///
+ /// Called when a new platform device is added or discovered.
+ /// Implementers should attempt to initialize the device here.
+ fn probe(dev: &mut Device, id_info: &Self::IdInfo) -> Result<Pin<KBox<Self>>>;
+}
+
+/// The PCI device representation.
+///
+/// A PCI device is based on an always reference counted `device:Device` instance. Cloning a PCI
+/// device, hence, also increments the base device' reference count.
+#[derive(Clone)]
+pub struct Device(ARef<device::Device>);
+
+impl Device {
+ /// Create a PCI Device instance from an existing `device::Device`.
+ ///
+ /// # Safety
+ ///
+ /// `dev` must be an `ARef<device::Device>` whose underlying `bindings::device` is a member of
+ /// a `bindings::pci_dev`.
+ pub unsafe fn from_dev(dev: ARef<device::Device>) -> Self {
+ Self(dev)
+ }
+
+ fn as_raw(&self) -> *mut bindings::pci_dev {
+ // SAFETY: By the type invariant `self.0.as_raw` is a pointer to the `struct device`
+ // embedded in `struct pci_dev`.
+ unsafe { container_of!(self.0.as_raw(), bindings::pci_dev, dev) as _ }
+ }
+
+ /// Returns the PCI vendor ID.
+ pub fn vendor_id(&self) -> u16 {
+ // SAFETY: `self.as_raw` is a valid pointer to a `struct pci_dev`.
+ unsafe { (*self.as_raw()).vendor }
+ }
+
+ /// Returns the PCI device ID.
+ pub fn device_id(&self) -> u16 {
+ // SAFETY: `self.as_raw` is a valid pointer to a `struct pci_dev`.
+ unsafe { (*self.as_raw()).device }
+ }
+
+ /// Enable memory resources for this device.
+ pub fn enable_device_mem(&self) -> Result {
+ // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`.
+ let ret = unsafe { bindings::pci_enable_device_mem(self.as_raw()) };
+ if ret != 0 {
+ Err(Error::from_errno(ret))
+ } else {
+ Ok(())
+ }
+ }
+
+ /// Enable bus-mastering for this device.
+ pub fn set_master(&self) {
+ // SAFETY: `self.as_raw` is guaranteed to be a pointer to a valid `struct pci_dev`.
+ unsafe { bindings::pci_set_master(self.as_raw()) };
+ }
+}
+
+impl AsRef<device::Device> for Device {
+ fn as_ref(&self) -> &device::Device {
+ &self.0
+ }
+}
--
2.47.1