[PATCH v2 09/10] rust: pci: add basic PCI device / driver abstractions

Danilo Krummrich
2024-06-18T23:41:22Z

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` and `pci::Driver::remove` 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::DriverOps` trait is implemented by
the `pci::Adapter`.

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

This patch is based on previous work from FUJITA Tomonori.

Co-developed-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Co-developed-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
---
rust/bindings/bindings_helper.h | 1 +
rust/helpers.c | 18 ++
rust/kernel/lib.rs | 2 +
rust/kernel/pci.rs | 325 ++++++++++++++++++++++++++++++++
4 files changed, 346 insertions(+)
create mode 100644 rust/kernel/pci.rs

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 18a3f05115cb..30ad2a0e22d7 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -12,6 +12,7 @@
#include <linux/firmware.h>
#include <linux/jiffies.h>
#include <linux/mdio.h>
+#include <linux/pci.h>
#include <linux/phy.h>
#include <linux/refcount.h>
#include <linux/sched.h>
diff --git a/rust/helpers.c b/rust/helpers.c
index 269f97698588..c7f90b457af5 100644
--- a/rust/helpers.c
+++ b/rust/helpers.c
@@ -28,6 +28,7 @@
#include <linux/errname.h>
#include <linux/io.h>
#include <linux/mutex.h>
+#include <linux/pci.h>
#include <linux/rcupdate.h>
#include <linux/refcount.h>
#include <linux/sched/signal.h>
@@ -293,6 +294,23 @@ int rust_helper_devm_add_action(struct device *dev, void (*action)(void *), void
}
EXPORT_SYMBOL_GPL(rust_helper_devm_add_action);

+void rust_helper_pci_set_drvdata(struct pci_dev *pdev, void *data)
+{
+ pci_set_drvdata(pdev, data);
+}
+EXPORT_SYMBOL_GPL(rust_helper_pci_set_drvdata);
+
+void *rust_helper_pci_get_drvdata(struct pci_dev *pdev)
+{
+ return pci_get_drvdata(pdev);
+}
+EXPORT_SYMBOL_GPL(rust_helper_pci_get_drvdata);
+
+u64 rust_helper_pci_resource_len(struct pci_dev *pdev, int barnr)
+{
+ return pci_resource_len(pdev, barnr);
+}
+
/*
* `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
* use it in contexts where Rust expects a `usize` like slice (array) indices.
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index ef9426e32c18..4a02946dbbd9 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -59,6 +59,8 @@
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..a8230474e9b8
--- /dev/null
+++ b/rust/kernel/pci.rs
@@ -0,0 +1,325 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Wrappers for the PCI subsystem
+//!
+//! C header: [`include/linux/pci.h`](srctree/include/linux/pci.h)
+
+use crate::{
+ bindings, container_of, device,
+ device_id::{IdTable, RawDeviceId},
+ driver,
+ error::{to_result, Result},
+ str::CStr,
+ types::{ARef, ForeignOwnable},
+ ThisModule,
+};
+use kernel::prelude::*; // for pinned_drop
+
+/// An adapter for the registration of PCI drivers.
+pub struct Adapter<T: Driver>(T);
+
+impl<T: Driver> driver::DriverOps for Adapter<T> {
+ type RegType = bindings::pci_driver;
+
+ fn register(
+ pdrv: &mut Self::RegType,
+ name: &'static CStr,
+ module: &'static ThisModule,
+ ) -> Result {
+ pdrv.name = name.as_char_ptr();
+ pdrv.probe = Some(Self::probe_callback);
+ pdrv.remove = Some(Self::remove_callback);
+ pdrv.id_table = T::ID_TABLE.as_ref();
+
+ // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
+ to_result(unsafe {
+ bindings::__pci_register_driver(pdrv as _, module.0, name.as_char_ptr())
+ })
+ }
+
+ fn unregister(pdrv: &mut Self::RegType) {
+ // SAFETY: `pdrv` is guaranteed to be a valid `RegType`.
+ unsafe { bindings::pci_unregister_driver(pdrv) }
+ }
+}
+
+impl<T: Driver> Adapter<T> {
+ extern "C" fn probe_callback(
+ pdev: *mut bindings::pci_dev,
+ id: *const bindings::pci_device_id,
+ ) -> core::ffi::c_int {
+ // SAFETY: Safe because the core kernel only ever calls the probe callback with a valid
+ // `pdev`.
+ let dev = unsafe { device::Device::from_raw(&mut (*pdev).dev) };
+ // SAFETY: Guaranteed by the rules described above.
+ let mut pdev = unsafe { Device::from_dev(dev) };
+
+ // SAFETY: `id` is a pointer within the static table, so it's always valid.
+ let offset = unsafe { (*id).driver_data };
+ let info = {
+ // SAFETY: The offset comes from a previous call to `offset_from` in `IdArray::new`,
+ // which guarantees that the resulting pointer is within the table.
+ let ptr = unsafe {
+ id.cast::<u8>()
+ .offset(offset as _)
+ .cast::<Option<T::IdInfo>>()
+ };
+ // SAFETY: Guaranteed by the preceding safety requirement.
+ unsafe { (*ptr).as_ref() }
+ };
+ match T::probe(&mut pdev, info) {
+ Ok(data) => {
+ // Let the `struct pci_dev` own a reference of the driver's private data.
+ // SAFETY: The core kernel only ever calls the probe callback with a valid `pdev`.
+ 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 core kernel only ever calls the probe callback with a valid `pdev`. `ptr`
+ // points to a valid reference of the driver's private data, as it was set by
+ // `Adapter::probe_callback`.
+ let data = unsafe {
+ let ptr = bindings::pci_get_drvdata(pdev);
+
+ T::Data::from_foreign(ptr)
+ };
+
+ T::remove(&data);
+ }
+}
+
+/// 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.
+#[derive(Clone, Copy)]
+pub struct DeviceId {
+ /// Vendor ID
+ pub vendor: u32,
+ /// Device ID
+ pub device: u32,
+ /// Subsystem vendor ID
+ pub subvendor: u32,
+ /// Subsystem device ID
+ pub subdevice: u32,
+ /// Device class and subclass
+ pub class: u32,
+ /// Limit which sub-fields of the class
+ pub class_mask: u32,
+}
+
+impl DeviceId {
+ const PCI_ANY_ID: u32 = !0;
+
+ /// PCI_DEVICE macro.
+ pub const fn new(vendor: u32, device: u32) -> Self {
+ Self {
+ vendor,
+ device,
+ subvendor: DeviceId::PCI_ANY_ID,
+ subdevice: DeviceId::PCI_ANY_ID,
+ class: 0,
+ class_mask: 0,
+ }
+ }
+
+ /// PCI_DEVICE_CLASS macro.
+ pub const fn with_class(class: u32, class_mask: u32) -> Self {
+ Self {
+ vendor: DeviceId::PCI_ANY_ID,
+ device: DeviceId::PCI_ANY_ID,
+ subvendor: DeviceId::PCI_ANY_ID,
+ subdevice: DeviceId::PCI_ANY_ID,
+ class,
+ class_mask,
+ }
+ }
+
+ /// PCI_DEVICE_ID macro.
+ pub const fn to_rawid(&self, offset: isize) -> bindings::pci_device_id {
+ bindings::pci_device_id {
+ vendor: self.vendor,
+ device: self.device,
+ subvendor: self.subvendor,
+ subdevice: self.subdevice,
+ class: self.class,
+ class_mask: self.class_mask,
+ driver_data: offset as _,
+ override_only: 0,
+ }
+ }
+}
+
+// SAFETY: `ZERO` is all zeroed-out and `to_rawid` stores `offset` in `pci_device_id::driver_data`.
+unsafe impl RawDeviceId for DeviceId {
+ type RawType = bindings::pci_device_id;
+
+ const ZERO: Self::RawType = bindings::pci_device_id {
+ vendor: 0,
+ device: 0,
+ subvendor: 0,
+ subdevice: 0,
+ class: 0,
+ class_mask: 0,
+ driver_data: 0,
+ override_only: 0,
+ };
+}
+
+/// Define a const pci device id table
+///
+/// # Examples
+///
+/// See [`Driver`]
+///
+#[macro_export]
+macro_rules! define_pci_id_table {
+ ($data_type:ty, $($t:tt)*) => {
+ type IdInfo = $data_type;
+ const ID_TABLE: $crate::device_id::IdTable<'static, $crate::pci::DeviceId, $data_type> = {
+ $crate::define_id_array!(ARRAY, $crate::pci::DeviceId, $data_type, $($t)* );
+ ARRAY.as_table()
+ };
+ };
+}
+pub use define_pci_id_table;
+
+/// The PCI driver trait.
+///
+/// # Example
+///
+///```
+/// # use kernel::{bindings, define_pci_id_table, pci, sync::Arc};
+///
+/// struct MyDriver;
+/// struct MyDeviceData;
+///
+/// impl pci::Driver for MyDriver {
+/// type Data = Arc<MyDeviceData>;
+///
+/// define_pci_id_table! {
+/// (),
+/// [ (pci::DeviceId::new(bindings::PCI_VENDOR_ID_REDHAT,
+/// bindings::PCI_ANY_ID as u32),
+/// None)
+/// ]
+/// }
+///
+/// fn probe(
+/// _pdev: &mut pci::Device,
+/// _id_info: Option<&Self::IdInfo>
+/// ) -> Result<Self::Data> {
+/// Err(ENODEV)
+/// }
+///
+/// fn remove(_data: &Self::Data) {
+/// }
+/// }
+///```
+/// 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 {
+ /// Data stored on device by driver.
+ ///
+ /// Corresponds to the data set or retrieved via the kernel's
+ /// `pci_{set,get}_drvdata()` functions.
+ ///
+ /// Require that `Data` implements `ForeignOwnable`. We guarantee to
+ /// never move the underlying wrapped data structure.
+ ///
+ /// TODO: Use associated_type_defaults once stabilized:
+ ///
+ /// `type Data: ForeignOwnable = ();`
+ type Data: ForeignOwnable;
+
+ /// 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<'static, DeviceId, 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: Option<&Self::IdInfo>) -> Result<Self::Data>;
+
+ /// PCI driver remove.
+ ///
+ /// Called when a platform device is removed.
+ /// Implementers should prepare the device for complete removal here.
+ fn remove(data: &Self::Data);
+}
+
+/// 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: Guaranteed by the type invaraints.
+ unsafe { container_of!(self.0.as_raw(), bindings::pci_dev, dev) as _ }
+ }
+
+ /// Enable the Device's memory.
+ pub fn enable_device_mem(&self) -> Result {
+ // SAFETY: Safe by the type invariants.
+ let ret = unsafe { bindings::pci_enable_device_mem(self.as_raw()) };
+ if ret != 0 {
+ Err(Error::from_errno(ret))
+ } else {
+ Ok(())
+ }
+ }
+
+ /// Set the Device's master.
+ pub fn set_master(&self) {
+ // SAFETY: Safe by the type invariants.
+ unsafe { bindings::pci_set_master(self.as_raw()) };
+ }
+}
+
+impl AsRef<device::Device> for Device {
+ fn as_ref(&self) -> &device::Device {
+ &self.0
+ }
+}
--
2.45.1