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([2a02:810d:4b3f:ee94:642:1aff:fe31:a19f]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-360750f2303sm15502597f8f.87.2024.06.18.16.41.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 18 Jun 2024 16:41:18 -0700 (PDT) From: Danilo Krummrich To: gregkh@linuxfoundation.org, rafael@kernel.org, bhelgaas@google.com, ojeda@kernel.org, alex.gaynor@gmail.com, wedsonaf@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, a.hindborg@samsung.com, aliceryhl@google.com, airlied@gmail.com, fujita.tomonori@gmail.com, lina@asahilina.net, pstanner@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, robh@kernel.org, daniel.almeida@collabora.com Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Danilo Krummrich Subject: [PATCH v2 09/10] rust: pci: add basic PCI device / driver abstractions Date: Wed, 19 Jun 2024 01:39:55 +0200 Message-ID: <20240618234025.15036-10-dakr@redhat.com> X-Mailer: git-send-email 2.45.1 In-Reply-To: <20240618234025.15036-1-dakr@redhat.com> References: <20240618234025.15036-1-dakr@redhat.com> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 Signed-off-by: FUJITA Tomonori Co-developed-by: Philipp Stanner Signed-off-by: Philipp Stanner Signed-off-by: Danilo Krummrich --- 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 #include #include +#include #include #include #include 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 #include #include +#include #include #include #include @@ -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); + +impl driver::DriverOps for Adapter { + 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 Adapter { + 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::() + .offset(offset as _) + .cast::>() + }; + // 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!(, $crate::pci::Adapter, { $($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; +/// +/// 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 { +/// 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; + + /// 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); + +impl Device { + /// Create a PCI Device instance from an existing `device::Device`. + /// + /// # Safety + /// + /// `dev` must be an `ARef` whose underlying `bindings::device` is a member of + /// a `bindings::pci_dev`. + pub unsafe fn from_dev(dev: ARef) -> 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 for Device { + fn as_ref(&self) -> &device::Device { + &self.0 + } +}