diff options
Diffstat (limited to 'rust/kernel/driver.rs')
| -rw-r--r-- | rust/kernel/driver.rs | 98 |
1 files changed, 78 insertions, 20 deletions
diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs index 9beae2e3d57e..bee3ae21a27b 100644 --- a/rust/kernel/driver.rs +++ b/rust/kernel/driver.rs @@ -33,7 +33,14 @@ //! } //! ``` //! -//! For specific examples see [`auxiliary::Driver`], [`pci::Driver`] and [`platform::Driver`]. +//! For specific examples see: +//! +//! * [`platform::Driver`](kernel::platform::Driver) +#" +)] +#")] //! //! The `probe()` callback should return a `impl PinInit<Self, Error>`, i.e. the driver's private //! data. The bus abstraction should store the pointer in the corresponding bus device. The generic @@ -79,7 +86,6 @@ //! //! For this purpose the generic infrastructure in [`device_id`] should be used. //! -//! [`auxiliary::Driver`]: kernel::auxiliary::Driver //! [`Core`]: device::Core //! [`Device`]: device::Device //! [`Device<Core>`]: device::Device<device::Core> @@ -87,31 +93,49 @@ //! [`DeviceContext`]: device::DeviceContext //! [`device_id`]: kernel::device_id //! [`module_driver`]: kernel::module_driver -//! [`pci::Driver`]: kernel::pci::Driver -//! [`platform::Driver`]: kernel::platform::Driver use crate::error::{Error, Result}; use crate::{acpi, device, of, str::CStr, try_pin_init, types::Opaque, ThisModule}; use core::pin::Pin; use pin_init::{pin_data, pinned_drop, PinInit}; +/// Trait describing the layout of a specific device driver. +/// +/// This trait describes the layout of a specific driver structure, such as `struct pci_driver` or +/// `struct platform_driver`. +/// +/// # Safety +/// +/// Implementors must guarantee that: +/// - `DriverType` is `repr(C)`, +/// - `DriverData` is the type of the driver's device private data. +/// - `DriverType` embeds a valid `struct device_driver` at byte offset `DEVICE_DRIVER_OFFSET`. +pub unsafe trait DriverLayout { + /// The specific driver type embedding a `struct device_driver`. + type DriverType: Default; + + /// The type of the driver's device private data. + type DriverData; + + /// Byte offset of the embedded `struct device_driver` within `DriverType`. + /// + /// This must correspond exactly to the location of the embedded `struct device_driver` field. + const DEVICE_DRIVER_OFFSET: usize; +} + /// The [`RegistrationOps`] trait serves as generic interface for subsystems (e.g., PCI, Platform, /// Amba, etc.) to provide the corresponding subsystem specific implementation to register / -/// unregister a driver of the particular type (`RegType`). +/// unregister a driver of the particular type (`DriverType`). /// -/// For instance, the PCI subsystem would set `RegType` to `bindings::pci_driver` and call +/// For instance, the PCI subsystem would set `DriverType` to `bindings::pci_driver` and call /// `bindings::__pci_register_driver` from `RegistrationOps::register` and /// `bindings::pci_unregister_driver` from `RegistrationOps::unregister`. /// /// # Safety /// -/// A call to [`RegistrationOps::unregister`] for a given instance of `RegType` is only valid if a -/// preceding call to [`RegistrationOps::register`] has been successful. -pub unsafe trait RegistrationOps { - /// The type that holds information about the registration. This is typically a struct defined - /// by the C portion of the kernel. - type RegType: Default; - +/// A call to [`RegistrationOps::unregister`] for a given instance of `DriverType` is only valid if +/// a preceding call to [`RegistrationOps::register`] has been successful. +pub unsafe trait RegistrationOps: DriverLayout { /// Registers a driver. /// /// # Safety @@ -119,7 +143,7 @@ pub unsafe trait RegistrationOps { /// On success, `reg` must remain pinned and valid until the matching call to /// [`RegistrationOps::unregister`]. unsafe fn register( - reg: &Opaque<Self::RegType>, + reg: &Opaque<Self::DriverType>, name: &'static CStr, module: &'static ThisModule, ) -> Result; @@ -130,7 +154,7 @@ pub unsafe trait RegistrationOps { /// /// Must only be called after a preceding successful call to [`RegistrationOps::register`] for /// the same `reg`. - unsafe fn unregister(reg: &Opaque<Self::RegType>); + unsafe fn unregister(reg: &Opaque<Self::DriverType>); } /// A [`Registration`] is a generic type that represents the registration of some driver type (e.g. @@ -142,7 +166,7 @@ pub unsafe trait RegistrationOps { #[pin_data(PinnedDrop)] pub struct Registration<T: RegistrationOps> { #[pin] - reg: Opaque<T::RegType>, + reg: Opaque<T::DriverType>, } // SAFETY: `Registration` has no fields or methods accessible via `&Registration`, so it is safe to @@ -153,17 +177,51 @@ unsafe impl<T: RegistrationOps> Sync for Registration<T> {} // any thread, so `Registration` is `Send`. unsafe impl<T: RegistrationOps> Send for Registration<T> {} -impl<T: RegistrationOps> Registration<T> { +impl<T: RegistrationOps + 'static> Registration<T> { + extern "C" fn post_unbind_callback(dev: *mut bindings::device) { + // SAFETY: The driver core only ever calls the post unbind callback with a valid pointer to + // a `struct device`. + // + // INVARIANT: `dev` is valid for the duration of the `post_unbind_callback()`. + let dev = unsafe { &*dev.cast::<device::Device<device::CoreInternal>>() }; + + // `remove()` and all devres callbacks have been completed at this point, hence drop the + // driver's device private data. + // + // SAFETY: By the safety requirements of the `Driver` trait, `T::DriverData` is the + // driver's device private data type. + drop(unsafe { dev.drvdata_obtain::<T::DriverData>() }); + } + + /// Attach generic `struct device_driver` callbacks. + fn callbacks_attach(drv: &Opaque<T::DriverType>) { + let ptr = drv.get().cast::<u8>(); + + // SAFETY: + // - `drv.get()` yields a valid pointer to `Self::DriverType`. + // - Adding `DEVICE_DRIVER_OFFSET` yields the address of the embedded `struct device_driver` + // as guaranteed by the safety requirements of the `Driver` trait. + let base = unsafe { ptr.add(T::DEVICE_DRIVER_OFFSET) }; + + // CAST: `base` points to the offset of the embedded `struct device_driver`. + let base = base.cast::<bindings::device_driver>(); + + // SAFETY: It is safe to set the fields of `struct device_driver` on initialization. + unsafe { (*base).p_cb.post_unbind_rust = Some(Self::post_unbind_callback) }; + } + /// Creates a new instance of the registration object. pub fn new(name: &'static CStr, module: &'static ThisModule) -> impl PinInit<Self, Error> { try_pin_init!(Self { - reg <- Opaque::try_ffi_init(|ptr: *mut T::RegType| { + reg <- Opaque::try_ffi_init(|ptr: *mut T::DriverType| { // SAFETY: `try_ffi_init` guarantees that `ptr` is valid for write. - unsafe { ptr.write(T::RegType::default()) }; + unsafe { ptr.write(T::DriverType::default()) }; // SAFETY: `try_ffi_init` guarantees that `ptr` is valid for write, and it has // just been initialised above, so it's also valid for read. - let drv = unsafe { &*(ptr as *const Opaque<T::RegType>) }; + let drv = unsafe { &*(ptr as *const Opaque<T::DriverType>) }; + + Self::callbacks_attach(drv); // SAFETY: `drv` is guaranteed to be pinned until `T::unregister`. unsafe { T::register(drv, name, module) } |