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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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//! Abstractions for the auxiliary bus.//!//! C header: [`include/linux/auxiliary_bus.h`](srctree/include/linux/auxiliary_bus.h)
use crate::{ bindings, container_of, device, device_id::{ RawDeviceId, RawDeviceIdIndex, // },
driver, error::{ from_result, to_result, // }, prelude::*, types::{ ForLt, ForeignOwnable, Opaque, // }, ThisModule, //};use core::{ any::TypeId, marker::PhantomData, mem::offset_of, pin::Pin, ptr::{ addr_of_mut, NonNull, // },};
/// An adapter for the registration of auxiliary drivers.pub struct Adapter<T: Driver>(T);
// SAFETY:// - `bindings::auxiliary_driver` is a C type declared as `repr(C)`.// - `T::Data` is the type of the driver's device private data.// - `struct auxiliary_driver` embeds a `struct device_driver`.// - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.unsafe impl<T: Driver> driver::DriverLayout for Adapter<T> { type DriverType = bindings::auxiliary_driver; type DriverData<'bound> = T::Data<'bound>; const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);}
// SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if// a preceding call to `register` has been successful.unsafe impl<T: Driver> driver::RegistrationOps for Adapter<T> { unsafe fn register( adrv: &Opaque<Self::DriverType>, name: &'static CStr, module: &'static ThisModule, ) -> Result { // SAFETY: It's safe to set the fields of `struct auxiliary_driver` on initialization. unsafe { (*adrv.get()).name = name.as_char_ptr(); (*adrv.get()).probe = Some(Self::probe_callback); (*adrv.get()).remove = Some(Self::remove_callback); (*adrv.get()).id_table = T::ID_TABLE.as_ptr(); }
// SAFETY: `adrv` is guaranteed to be a valid `DriverType`. to_result(unsafe { bindings::__auxiliary_driver_register(adrv.get(), module.0, name.as_char_ptr()) }) }
unsafe fn unregister(adrv: &Opaque<Self::DriverType>) { // SAFETY: `adrv` is guaranteed to be a valid `DriverType`. unsafe { bindings::auxiliary_driver_unregister(adrv.get()) } }}
impl<T: Driver> Adapter<T> { extern "C" fn probe_callback( adev: *mut bindings::auxiliary_device, id: *const bindings::auxiliary_device_id, ) -> c_int { // SAFETY: The auxiliary bus only ever calls the probe callback with a valid pointer to a // `struct auxiliary_device`. // // INVARIANT: `adev` is valid for the duration of `probe_callback()`. let adev = unsafe { &*adev.cast::<Device<device::CoreInternal<'_>>>() };
// SAFETY: `DeviceId` is a `#[repr(transparent)`] wrapper of `struct auxiliary_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());
from_result(|| { let data = T::probe(adev, info);
adev.as_ref().set_drvdata(data)?; Ok(0) }) }
extern "C" fn remove_callback(adev: *mut bindings::auxiliary_device) { // SAFETY: The auxiliary bus only ever calls the probe callback with a valid pointer to a // `struct auxiliary_device`. // // INVARIANT: `adev` is valid for the duration of `remove_callback()`. let adev = unsafe { &*adev.cast::<Device<device::CoreInternal<'_>>>() };
// SAFETY: `remove_callback` is only ever called after a successful call to // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called // and stored a `Pin<KBox<T::Data<'_>>>`. let data = unsafe { adev.as_ref().drvdata_borrow::<T::Data<'_>>() };
T::unbind(adev, data); }}
/// Declares a kernel module that exposes a single auxiliary driver.#[macro_export]macro_rules! module_auxiliary_driver { ($($f:tt)*) => { $crate::module_driver!(<T>, $crate::auxiliary::Adapter<T>, { $($f)* }); };}
/// Abstraction for `bindings::auxiliary_device_id`.#[repr(transparent)]#[derive(Clone, Copy)]pub struct DeviceId(bindings::auxiliary_device_id);
impl DeviceId { /// Create a new [`DeviceId`] from name. pub const fn new(modname: &'static CStr, name: &'static CStr) -> Self { let name = name.to_bytes_with_nul(); let modname = modname.to_bytes_with_nul();
let mut id: bindings::auxiliary_device_id = pin_init::zeroed(); let mut i = 0; while i < modname.len() { id.name[i] = modname[i]; i += 1; }
// Reuse the space of the NULL terminator. id.name[i - 1] = b'.';
let mut j = 0; while j < name.len() { id.name[i] = name[j]; i += 1; j += 1; }
Self(id) }}
// SAFETY: `DeviceId` is a `#[repr(transparent)]` wrapper of `auxiliary_device_id` and does not add// additional invariants, so it's safe to transmute to `RawType`.unsafe impl RawDeviceId for DeviceId { type RawType = bindings::auxiliary_device_id;}
// SAFETY: `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field.unsafe impl RawDeviceIdIndex for DeviceId { const DRIVER_DATA_OFFSET: usize = core::mem::offset_of!(bindings::auxiliary_device_id, driver_data);
fn index(&self) -> usize { self.0.driver_data }}
/// IdTable type for auxiliary drivers.pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;
/// Create a auxiliary `IdTable` with its alias for modpost.#[macro_export]macro_rules! auxiliary_device_table { ($table_name:ident, $module_table_name:ident, $id_info_type: ty, $table_data: expr) => { const $table_name: $crate::device_id::IdArray< $crate::auxiliary::DeviceId, $id_info_type, { $table_data.len() }, > = $crate::device_id::IdArray::new($table_data);
$crate::module_device_table!("auxiliary", $module_table_name, $table_name); };}
/// The auxiliary driver trait.////// Drivers must implement this trait in order to get an auxiliary driver registered.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 type of the driver's bus device private data. type Data<'bound>: Send + 'bound;
/// The table of device ids supported by the driver. const ID_TABLE: IdTable<Self::IdInfo>;
/// Auxiliary driver probe. /// /// Called when an auxiliary device is matches a corresponding driver. fn probe<'bound>( dev: &'bound Device<device::Core<'_>>, id_info: &'bound Self::IdInfo, ) -> impl PinInit<Self::Data<'bound>, Error> + 'bound;
/// Auxiliary driver unbind. /// /// Called when a [`Device`] is unbound from its bound [`Driver`]. Implementing this callback /// is optional. /// /// This callback serves as a place for drivers to perform teardown operations that require a /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O /// operations to gracefully tear down the device. /// /// Otherwise, release operations for driver resources should be performed in `Drop`. fn unbind<'bound>(dev: &'bound Device<device::Core<'_>>, this: Pin<&Self::Data<'bound>>) { let _ = (dev, this); }}
/// The auxiliary device representation.////// This structure represents the Rust abstraction for a C `struct auxiliary_device`. The/// implementation abstracts the usage of an already existing C `struct auxiliary_device` within/// Rust code that we get passed from the C side.////// # Invariants////// A [`Device`] instance represents a valid `struct auxiliary_device` created by the C portion of/// the kernel.#[repr(transparent)]pub struct Device<Ctx: device::DeviceContext = device::Normal>( Opaque<bindings::auxiliary_device>, PhantomData<Ctx>,);
impl<Ctx: device::DeviceContext> Device<Ctx> { fn as_raw(&self) -> *mut bindings::auxiliary_device { self.0.get() }
/// Returns the auxiliary device' id. pub fn id(&self) -> u32 { // SAFETY: By the type invariant `self.as_raw()` is a valid pointer to a // `struct auxiliary_device`. unsafe { (*self.as_raw()).id } }}
impl Device<device::Bound> { /// Returns a bound reference to the parent [`device::Device`]. pub fn parent(&self) -> &device::Device<device::Bound> { let parent = (**self).parent();
// SAFETY: A bound auxiliary device always has a bound parent device. unsafe { parent.as_bound() } }
/// Returns a pinned reference to the registration data set by the registering (parent) driver. /// /// `F` is the [`ForLt`](trait@ForLt) encoding of the data type. The returned /// reference has its lifetime shortened from `'static` to `&self`'s borrow lifetime via /// [`ForLt::cast_ref`]. /// /// Returns [`EINVAL`] if `F` does not match the type used by the parent driver when calling /// [`Registration::new()`]. /// /// Returns [`ENOENT`] if no registration data has been set, e.g. when the device was /// registered by a C driver. pub fn registration_data<F: ForLt + 'static>(&self) -> Result<Pin<&F::Of<'_>>> { // SAFETY: By the type invariant, `self.as_raw()` is a valid `struct auxiliary_device`. let ptr = unsafe { (*self.as_raw()).registration_data_rust }; if ptr.is_null() { dev_warn!( self.as_ref(), "No registration data set; parent is not a Rust driver.\n" ); return Err(ENOENT); }
// SAFETY: `ptr` is non-null and was set via `into_foreign()` in `Registration::new()`; // `RegistrationData` is `#[repr(C)]` with `type_id` at offset 0, so reading a `TypeId` // at the start of the allocation is valid regardless of `F`. let type_id = unsafe { ptr.cast::<TypeId>().read() }; if type_id != TypeId::of::<F>() { return Err(EINVAL); }
// SAFETY: The `TypeId` check above confirms that the stored type matches // `F::Of<'static>`; `ptr` remains valid until `Registration::drop()` calls // `from_foreign()`. let wrapper = unsafe { Pin::<KBox<RegistrationData<F::Of<'static>>>>::borrow(ptr) };
// SAFETY: `data` is a structurally pinned field of `RegistrationData`. let pinned: Pin<&F::Of<'_>> = unsafe { wrapper.map_unchecked(|w| &w.data) };
// SAFETY: The data was pinned when stored; `cast_ref` only shortens // the lifetime, so the pinning guarantee is preserved. Ok(unsafe { Pin::new_unchecked(F::cast_ref(pinned.get_ref())) }) }}
impl Device { /// Returns a reference to the parent [`device::Device`]. pub fn parent(&self) -> &device::Device { // SAFETY: A `struct auxiliary_device` always has a parent. unsafe { self.as_ref().parent().unwrap_unchecked() } }
extern "C" fn release(dev: *mut bindings::device) { // SAFETY: By the type invariant `self.0.as_raw` is a pointer to the `struct device` // embedded in `struct auxiliary_device`. let adev = unsafe { container_of!(dev, bindings::auxiliary_device, dev) };
// SAFETY: `adev` points to the memory that has been allocated in `Registration::new`, via // `KBox::new(Opaque::<bindings::auxiliary_device>::zeroed(), GFP_KERNEL)`. let _ = unsafe { KBox::<Opaque<bindings::auxiliary_device>>::from_raw(adev.cast()) }; }}
// SAFETY: `auxiliary::Device` is a transparent wrapper of `struct auxiliary_device`.// The offset is guaranteed to point to a valid device field inside `auxiliary::Device`.unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for Device<Ctx> { const OFFSET: usize = offset_of!(bindings::auxiliary_device, dev);}
// SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic// argument.kernel::impl_device_context_deref!(unsafe { Device });kernel::impl_device_context_into_aref!(Device);
// SAFETY: Instances of `Device` are always reference-counted.unsafe impl crate::sync::aref::AlwaysRefCounted for Device { fn inc_ref(&self) { // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero. unsafe { bindings::get_device(self.as_ref().as_raw()) }; }
unsafe fn dec_ref(obj: NonNull<Self>) { // CAST: `Self` a transparent wrapper of `bindings::auxiliary_device`. let adev: *mut bindings::auxiliary_device = obj.cast().as_ptr();
// SAFETY: By the type invariant of `Self`, `adev` is a pointer to a valid // `struct auxiliary_device`. let dev = unsafe { addr_of_mut!((*adev).dev) };
// SAFETY: The safety requirements guarantee that the refcount is non-zero. unsafe { bindings::put_device(dev) } }}
impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for Device<Ctx> { fn as_ref(&self) -> &device::Device<Ctx> { // SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid // `struct auxiliary_device`. let dev = unsafe { addr_of_mut!((*self.as_raw()).dev) };
// SAFETY: `dev` points to a valid `struct device`. unsafe { device::Device::from_raw(dev) } }}
// SAFETY: A `Device` is always reference-counted and can be released from any thread.unsafe impl Send for Device {}
// SAFETY: `Device` can be shared among threads because all methods of `Device`// (i.e. `Device<Normal>) are thread safe.unsafe impl Sync for Device {}
// SAFETY: Same as `Device<Normal>` -- the underlying `struct auxiliary_device` is the same;// `Bound` is a zero-sized type-state marker that does not affect thread safety.unsafe impl Sync for Device<device::Bound> {}
/// Wrapper that stores a [`TypeId`] alongside the registration data for runtime type checking.#[repr(C)]#[pin_data]struct RegistrationData<T> { type_id: TypeId, #[pin] data: T,}
/// The registration of an auxiliary device.////// This type represents the registration of a [`struct auxiliary_device`]. When its parent device/// is unbound, the corresponding auxiliary device will be unregistered from the system.////// The type parameter `F` is a [`ForLt`](trait@ForLt) encoding of the registration/// data type. For non-lifetime-parameterized types, use [`ForLt!(T)`](macro@ForLt)./// The data can be accessed by the auxiliary driver through [`Device::registration_data()`].////// # Invariants////// `self.adev` always holds a valid pointer to an initialized and registered/// [`struct auxiliary_device`] whose `registration_data_rust` field points to a/// valid `Pin<KBox<RegistrationData<F::Of<'static>>>>`.pub struct Registration<'a, F: ForLt + 'static> { adev: NonNull<bindings::auxiliary_device>, _phantom: PhantomData<F::Of<'a>>,}
impl<'a, F: ForLt> Registration<'a, F>where for<'b> F::Of<'b>: Send + Sync,{ /// Create and register a new auxiliary device with the given registration data. /// /// The `data` is owned by the registration and can be accessed through the auxiliary device /// via [`Device::registration_data()`]. /// /// # Safety /// /// The caller must not `mem::forget()` the returned [`Registration`] or otherwise prevent its /// [`Drop`] implementation from running, since the registration data may contain borrowed /// references that become invalid after `'a` ends. /// /// If the registration data is `'static`, use the safe [`Registration::new()`] instead. pub unsafe fn new_with_lt<E>( parent: &'a device::Device<device::Bound>, name: &CStr, id: u32, modname: &CStr, data: impl PinInit<F::Of<'a>, E>, ) -> Result<Self> where Error: From<E>, { let data = KBox::pin_init::<Error>( try_pin_init!(RegistrationData { type_id: TypeId::of::<F>(), data <- data, }), GFP_KERNEL, )?;
// SAFETY: `'a` is invariant (via `Registration`'s `PhantomData`). Lifetimes do not // affect layout, so RegistrationData<F::Of<'a>> and RegistrationData<F::Of<'static>> // have identical representation. let data: Pin<KBox<RegistrationData<F::Of<'static>>>> = unsafe { core::mem::transmute(data) };
let boxed: KBox<Opaque<bindings::auxiliary_device>> = KBox::zeroed(GFP_KERNEL)?; let adev = boxed.get();
// SAFETY: It's safe to set the fields of `struct auxiliary_device` on initialization. unsafe { (*adev).dev.parent = parent.as_raw(); (*adev).dev.release = Some(Device::release); (*adev).name = name.as_char_ptr(); (*adev).id = id; (*adev).registration_data_rust = data.into_foreign(); }
// SAFETY: `adev` is guaranteed to be a valid pointer to a `struct auxiliary_device`, // which has not been initialized yet. unsafe { bindings::auxiliary_device_init(adev) };
// Now that `adev` is initialized, leak the `Box`; the corresponding memory will be // freed by `Device::release` when the last reference to the `struct auxiliary_device` // is dropped. let _ = KBox::into_raw(boxed);
// SAFETY: // - `adev` is guaranteed to be a valid pointer to a `struct auxiliary_device`, which // has been initialized, // - `modname.as_char_ptr()` is a NULL terminated string. let ret = unsafe { bindings::__auxiliary_device_add(adev, modname.as_char_ptr()) }; if ret != 0 { // SAFETY: `registration_data` was set above via `into_foreign()`. drop(unsafe { Pin::<KBox<RegistrationData<F::Of<'static>>>>::from_foreign( (*adev).registration_data_rust, ) });
// SAFETY: `adev` is guaranteed to be a valid pointer to a // `struct auxiliary_device`, which has been initialized. unsafe { bindings::auxiliary_device_uninit(adev) };
return Err(Error::from_errno(ret)); }
// INVARIANT: The device will remain registered until `auxiliary_device_delete()` is // called, which happens in `Self::drop()`. Ok(Self { // SAFETY: `adev` is guaranteed to be non-null, since the `KBox` was allocated // successfully. adev: unsafe { NonNull::new_unchecked(adev) }, _phantom: PhantomData, }) }
/// Create and register a new auxiliary device with `'static` registration data. /// /// Safe variant of [`Registration::new_with_lt()`] for registration data that does not contain /// borrowed references. pub fn new<E>( parent: &'a device::Device<device::Bound>, name: &CStr, id: u32, modname: &CStr, data: impl PinInit<F::Of<'a>, E>, ) -> Result<Self> where F::Of<'a>: 'static, Error: From<E>, { // SAFETY: `F::Of<'a>: 'static` guarantees the data contains no borrowed references, // so forgetting the `Registration` cannot cause use-after-free. unsafe { Self::new_with_lt(parent, name, id, modname, data) } }}
impl<F: ForLt> Drop for Registration<'_, F> { fn drop(&mut self) { // SAFETY: By the type invariant of `Self`, `self.adev.as_ptr()` is a valid registered // `struct auxiliary_device`. unsafe { bindings::auxiliary_device_delete(self.adev.as_ptr()) };
// SAFETY: `registration_data` was set in `new()` via `into_foreign()`. drop(unsafe { Pin::<KBox<RegistrationData<F::Of<'static>>>>::from_foreign( (*self.adev.as_ptr()).registration_data_rust, ) });
// This drops the reference we acquired through `auxiliary_device_init()`. // // SAFETY: By the type invariant of `Self`, `self.adev.as_ptr()` is a valid registered // `struct auxiliary_device`. unsafe { bindings::auxiliary_device_uninit(self.adev.as_ptr()) }; }}
// SAFETY: A `Registration` of a `struct auxiliary_device` can be released from any thread.unsafe impl<F: ForLt> Send for Registration<'_, F> where for<'a> F::Of<'a>: Send {}
// SAFETY: `Registration` does not expose any methods or fields that need synchronization.unsafe impl<F: ForLt> Sync for Registration<'_, F> where for<'a> F::Of<'a>: Send {}