// SPDX-License-Identifier: GPL-2.0 //! Generic devices that are part of the kernel's driver model.//!//! C header: [`include/linux/device.h`](srctree/include/linux/device.h) use crate::{    bindings,    fmt,    prelude::*,    sync::aref::ARef,    types::{        ForeignOwnable,        Opaque, //    }, //};use core::{    marker::PhantomData,    ptr, //}; pub mod property; /// The core representation of a device in the kernel's driver model.////// This structure represents the Rust abstraction for a C `struct device`. A [`Device`] can either/// exist as temporary reference (see also [`Device::from_raw`]), which is only valid within a/// certain scope or as [`ARef<Device>`], owning a dedicated reference count.////// # Device Types////// A [`Device`] can represent either a bus device or a class device.////// ## Bus Devices////// A bus device is a [`Device`] that is associated with a physical or virtual bus. Examples of/// buses include PCI, USB, I2C, and SPI. Devices attached to a bus are registered with a specific/// bus type, which facilitates matching devices with appropriate drivers based on IDs or other/// identifying information. Bus devices are visible in sysfs under `/sys/bus/<bus-name>/devices/`.////// ## Class Devices////// A class device is a [`Device`] that is associated with a logical category of functionality/// rather than a physical bus. Examples of classes include block devices, network interfaces, sound/// cards, and input devices. Class devices are grouped under a common class and exposed to/// userspace via entries in `/sys/class/<class-name>/`.////// # Device Context////// [`Device`] references are generic over a [`DeviceContext`], which represents the type state of/// a [`Device`].////// As the name indicates, this type state represents the context of the scope the [`Device`]/// reference is valid in. For instance, the [`Bound`] context guarantees that the [`Device`] is/// bound to a driver for the entire duration of the existence of a [`Device<Bound>`] reference.////// Other [`DeviceContext`] types besides [`Bound`] are [`Normal`], [`Core`] and [`CoreInternal`].////// Unless selected otherwise [`Device`] defaults to the [`Normal`] [`DeviceContext`], which by/// itself has no additional requirements.////// It is always up to the caller of [`Device::from_raw`] to select the correct [`DeviceContext`]/// type for the corresponding scope the [`Device`] reference is created in.////// All [`DeviceContext`] types other than [`Normal`] are intended to be used with/// [bus devices](#bus-devices) only.////// # Implementing Bus Devices////// This section provides a guideline to implement bus specific devices, such as:#[cfg_attr(CONFIG_PCI, doc = "* [`pci::Device`](kernel::pci::Device)")]/// * [`platform::Device`]////// A bus specific device should be defined as follows.////// ```ignore/// #[repr(transparent)]/// pub struct Device<Ctx: device::DeviceContext = device::Normal>(///     Opaque<bindings::bus_device_type>,///     PhantomData<Ctx>,/// );/// ```////// Since devices are reference counted, [`AlwaysRefCounted`] should be implemented for `Device`/// (i.e. `Device<Normal>`). Note that [`AlwaysRefCounted`] must not be implemented for any other/// [`DeviceContext`], since all other device context types are only valid within a certain scope.////// In order to be able to implement the [`DeviceContext`] dereference hierarchy, bus device/// implementations should call the [`impl_device_context_deref`] macro as shown below.////// ```ignore/// // 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 });/// ```////// In order to convert from a any [`Device<Ctx>`] to [`ARef<Device>`], bus devices can implement/// the following macro call.////// ```ignore/// kernel::impl_device_context_into_aref!(Device);/// ```////// Bus devices should also implement the following [`AsRef`] implementation, such that users can/// easily derive a generic [`Device`] reference.////// ```ignore/// impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for Device<Ctx> {///     fn as_ref(&self) -> &device::Device<Ctx> {///         ...///     }/// }/// ```////// # Implementing Class Devices////// Class device implementations require less infrastructure and depend slightly more on the/// specific subsystem.////// An example implementation for a class device could look like this.////// ```ignore/// #[repr(C)]/// pub struct Device<T: class::Driver> {///     dev: Opaque<bindings::class_device_type>,///     data: T::Data,/// }/// ```////// This class device uses the sub-classing pattern to embed the driver's private data within the/// allocation of the class device. For this to be possible the class device is generic over the/// class specific `Driver` trait implementation.////// Just like any device, class devices are reference counted and should hence implement/// [`AlwaysRefCounted`] for `Device`.////// Class devices should also implement the following [`AsRef`] implementation, such that users can/// easily derive a generic [`Device`] reference.////// ```ignore/// impl<T: class::Driver> AsRef<device::Device> for Device<T> {///     fn as_ref(&self) -> &device::Device {///         ...///     }/// }/// ```////// An example for a class device implementation is#[cfg_attr(CONFIG_DRM = "y", doc = "[`drm::Device`](kernel::drm::Device).")]#[cfg_attr(not(CONFIG_DRM = "y"), doc = "`drm::Device`.")]////// # Invariants////// A `Device` instance represents a valid `struct device` created by the C portion of the kernel.////// Instances of this type are always reference-counted, that is, a call to `get_device` ensures/// that the allocation remains valid at least until the matching call to `put_device`.////// `bindings::device::release` is valid to be called from any thread, hence `ARef<Device>` can be/// dropped from any thread.////// [`AlwaysRefCounted`]: kernel::sync::aref::AlwaysRefCounted/// [`impl_device_context_deref`]: kernel::impl_device_context_deref/// [`platform::Device`]: kernel::platform::Device#[repr(transparent)]pub struct Device<Ctx: DeviceContext = Normal>(Opaque<bindings::device>, PhantomData<Ctx>); impl Device {    /// Creates a new reference-counted abstraction instance of an existing `struct device` pointer.    ///    /// # Safety    ///    /// Callers must ensure that `ptr` is valid, non-null, and has a non-zero reference count,    /// i.e. it must be ensured that the reference count of the C `struct device` `ptr` points to    /// can't drop to zero, for the duration of this function call.    ///    /// It must also be ensured that `bindings::device::release` can be called from any thread.    /// While not officially documented, this should be the case for any `struct device`.    pub unsafe fn get_device(ptr: *mut bindings::device) -> ARef<Self> {        // SAFETY: By the safety requirements ptr is valid        unsafe { Self::from_raw(ptr) }.into()    }     /// Convert a [`&Device`](Device) into a [`&Device<Bound>`](Device<Bound>).    ///    /// # Safety    ///    /// The caller is responsible to ensure that the returned [`&Device<Bound>`](Device<Bound>)    /// only lives as long as it can be guaranteed that the [`Device`] is actually bound.    pub unsafe fn as_bound(&self) -> &Device<Bound> {        let ptr = core::ptr::from_ref(self);         // CAST: By the safety requirements the caller is responsible to guarantee that the        // returned reference only lives as long as the device is actually bound.        let ptr = ptr.cast();         // SAFETY:        // - `ptr` comes from `from_ref(self)` above, hence it's guaranteed to be valid.        // - Any valid `Device` pointer is also a valid pointer for `Device<Bound>`.        unsafe { &*ptr }    }} impl<'a> Device<CoreInternal<'a>> {    /// Store a pointer to the bound driver's private data.    pub fn set_drvdata<T>(&self, data: impl PinInit<T, Error>) -> Result {        let data = KBox::pin_init(data, GFP_KERNEL)?;         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.        unsafe { bindings::dev_set_drvdata(self.as_raw(), data.into_foreign().cast()) };         Ok(())    }     /// Take ownership of the private data stored in this [`Device`].    ///    /// # Safety    ///    /// - The type `T` must match the type of the `ForeignOwnable` previously stored by    ///   [`Device::set_drvdata`].    pub(crate) unsafe fn drvdata_obtain<T>(&self) -> Option<Pin<KBox<T>>> {        // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.        let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) };         // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.        unsafe { bindings::dev_set_drvdata(self.as_raw(), core::ptr::null_mut()) };         if ptr.is_null() {            return None;        }         // SAFETY:        // - If `ptr` is not NULL, it comes from a previous call to `into_foreign()`.        // - `dev_get_drvdata()` guarantees to return the same pointer given to `dev_set_drvdata()`        //   in `into_foreign()`.        Some(unsafe { Pin::<KBox<T>>::from_foreign(ptr.cast()) })    }     /// Borrow the driver's private data bound to this [`Device`].    ///    /// # Safety    ///    /// - Must only be called after a preceding call to [`Device::set_drvdata`] and before the    ///   device is fully unbound.    /// - The type `T` must match the type of the `ForeignOwnable` previously stored by    ///   [`Device::set_drvdata`].    pub unsafe fn drvdata_borrow<T>(&self) -> Pin<&T> {        // SAFETY: `drvdata_unchecked()` has the exact same safety requirements as the ones        // required by this method.        unsafe { self.drvdata_unchecked() }    }} impl Device<Bound> {    /// Borrow the driver's private data bound to this [`Device`].    ///    /// # Safety    ///    /// - Must only be called after a preceding call to [`Device::set_drvdata`] and before    ///   the device is fully unbound.    /// - The type `T` must match the type of the `ForeignOwnable` previously stored by    ///   [`Device::set_drvdata`].    unsafe fn drvdata_unchecked<T>(&self) -> Pin<&T> {        // SAFETY: By the type invariants, `self.as_raw()` is a valid pointer to a `struct device`.        let ptr = unsafe { bindings::dev_get_drvdata(self.as_raw()) };         // SAFETY:        // - By the safety requirements of this function, `ptr` comes from a previous call to        //   `into_foreign()`.        // - `dev_get_drvdata()` guarantees to return the same pointer given to `dev_set_drvdata()`        //   in `into_foreign()`.        unsafe { Pin::<KBox<T>>::borrow(ptr.cast()) }    }} impl<Ctx: DeviceContext> Device<Ctx> {    /// Obtain the raw `struct device *`.    pub(crate) fn as_raw(&self) -> *mut bindings::device {        self.0.get()    }     /// Returns a reference to the parent device, if any.    #[cfg_attr(not(CONFIG_AUXILIARY_BUS), expect(dead_code))]    pub(crate) fn parent(&self) -> Option<&Device> {        // SAFETY:        // - By the type invariant `self.as_raw()` is always valid.        // - The parent device is only ever set at device creation.        let parent = unsafe { (*self.as_raw()).parent };         if parent.is_null() {            None        } else {            // SAFETY:            // - Since `parent` is not NULL, it must be a valid pointer to a `struct device`.            // - `parent` is valid for the lifetime of `self`, since a `struct device` holds a            //   reference count of its parent.            Some(unsafe { Device::from_raw(parent) })        }    }     /// Convert a raw C `struct device` pointer to a `&'a Device`.    ///    /// # Safety    ///    /// Callers must ensure that `ptr` is valid, non-null, and has a non-zero reference count,    /// i.e. it must be ensured that the reference count of the C `struct device` `ptr` points to    /// can't drop to zero, for the duration of this function call and the entire duration when the    /// returned reference exists.    pub unsafe fn from_raw<'a>(ptr: *mut bindings::device) -> &'a Self {        // SAFETY: Guaranteed by the safety requirements of the function.        unsafe { &*ptr.cast() }    }     /// Prints an emergency-level message (level 0) prefixed with device information.    ///    /// More details are available from [`dev_emerg`].    ///    /// [`dev_emerg`]: crate::dev_emerg    pub fn pr_emerg(&self, args: fmt::Arguments<'_>) {        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.        unsafe { self.printk(bindings::KERN_EMERG, args) };    }     /// Prints an alert-level message (level 1) prefixed with device information.    ///    /// More details are available from [`dev_alert`].    ///    /// [`dev_alert`]: crate::dev_alert    pub fn pr_alert(&self, args: fmt::Arguments<'_>) {        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.        unsafe { self.printk(bindings::KERN_ALERT, args) };    }     /// Prints a critical-level message (level 2) prefixed with device information.    ///    /// More details are available from [`dev_crit`].    ///    /// [`dev_crit`]: crate::dev_crit    pub fn pr_crit(&self, args: fmt::Arguments<'_>) {        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.        unsafe { self.printk(bindings::KERN_CRIT, args) };    }     /// Prints an error-level message (level 3) prefixed with device information.    ///    /// More details are available from [`dev_err`].    ///    /// [`dev_err`]: crate::dev_err    pub fn pr_err(&self, args: fmt::Arguments<'_>) {        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.        unsafe { self.printk(bindings::KERN_ERR, args) };    }     /// Prints a warning-level message (level 4) prefixed with device information.    ///    /// More details are available from [`dev_warn`].    ///    /// [`dev_warn`]: crate::dev_warn    pub fn pr_warn(&self, args: fmt::Arguments<'_>) {        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.        unsafe { self.printk(bindings::KERN_WARNING, args) };    }     /// Prints a notice-level message (level 5) prefixed with device information.    ///    /// More details are available from [`dev_notice`].    ///    /// [`dev_notice`]: crate::dev_notice    pub fn pr_notice(&self, args: fmt::Arguments<'_>) {        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.        unsafe { self.printk(bindings::KERN_NOTICE, args) };    }     /// Prints an info-level message (level 6) prefixed with device information.    ///    /// More details are available from [`dev_info`].    ///    /// [`dev_info`]: crate::dev_info    pub fn pr_info(&self, args: fmt::Arguments<'_>) {        // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.        unsafe { self.printk(bindings::KERN_INFO, args) };    }     /// Prints a debug-level message (level 7) prefixed with device information.    ///    /// More details are available from [`dev_dbg`].    ///    /// [`dev_dbg`]: crate::dev_dbg    pub fn pr_dbg(&self, args: fmt::Arguments<'_>) {        if cfg!(debug_assertions) {            // SAFETY: `klevel` is null-terminated, uses one of the kernel constants.            unsafe { self.printk(bindings::KERN_DEBUG, args) };        }    }     /// Prints the provided message to the console.    ///    /// # Safety    ///    /// Callers must ensure that `klevel` is null-terminated; in particular, one of the    /// `KERN_*`constants, for example, `KERN_CRIT`, `KERN_ALERT`, etc.    #[cfg_attr(not(CONFIG_PRINTK), allow(unused_variables))]    unsafe fn printk(&self, klevel: &[u8], msg: fmt::Arguments<'_>) {        // SAFETY: `klevel` is null-terminated and one of the kernel constants. `self.as_raw`        // is valid because `self` is valid. The "%pA" format string expects a pointer to        // `fmt::Arguments`, which is what we're passing as the last argument.        #[cfg(CONFIG_PRINTK)]        unsafe {            bindings::_dev_printk(                klevel.as_ptr().cast::<crate::ffi::c_char>(),                self.as_raw(),                c"%pA".as_char_ptr(),                core::ptr::from_ref(&msg).cast::<crate::ffi::c_void>(),            )        };    }     /// Obtain the [`FwNode`](property::FwNode) corresponding to this [`Device`].    pub fn fwnode(&self) -> Option<&property::FwNode> {        // SAFETY: `self` is valid.        let fwnode_handle = unsafe { bindings::__dev_fwnode(self.as_raw()) };        if fwnode_handle.is_null() {            return None;        }        // SAFETY: `fwnode_handle` is valid. Its lifetime is tied to `&self`. We        // return a reference instead of an `ARef<FwNode>` because `dev_fwnode()`        // doesn't increment the refcount. It is safe to cast from a        // `struct fwnode_handle*` to a `*const FwNode` because `FwNode` is        // defined as a `#[repr(transparent)]` wrapper around `fwnode_handle`.        Some(unsafe { &*fwnode_handle.cast() })    }     /// Returns the name of the device.    ///    /// This is the kobject name of the device, or its initial name if the kobject is not yet    /// available.    #[inline]    pub fn name(&self) -> &CStr {        // SAFETY: By its type invariant `self.as_raw()` is a valid pointer to a `struct device`.        // The returned string is valid for the lifetime of the device.        unsafe { CStr::from_char_ptr(bindings::dev_name(self.as_raw())) }    }} // 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_raw()) };    }     unsafe fn dec_ref(obj: ptr::NonNull<Self>) {        // SAFETY: The safety requirements guarantee that the refcount is non-zero.        unsafe { bindings::put_device(obj.cast().as_ptr()) }    }} // SAFETY: As by the type invariant `Device` can be sent to any thread.unsafe impl Send for Device {} // SAFETY: `Device` can be shared among threads because all immutable methods are protected by the// synchronization in `struct device`.unsafe impl Sync for Device {} // SAFETY: Same as `Device<Normal>` -- the underlying `struct device` is the same; `Bound` is a// zero-sized type-state marker that does not affect thread safety.unsafe impl Sync for Device<Bound> {} /// Marker trait for the context or scope of a bus specific device.////// [`DeviceContext`] is a marker trait for types representing the context of a bus specific/// [`Device`].////// The specific device context types are: [`CoreInternal`], [`Core`], [`Bound`] and [`Normal`].////// [`DeviceContext`] types are hierarchical, which means that there is a strict hierarchy that/// defines which [`DeviceContext`] type can be derived from another. For instance, any/// [`Device<Core>`] can dereference to a [`Device<Bound>`].////// The following enumeration illustrates the dereference hierarchy of [`DeviceContext`] types.////// - [`CoreInternal`] => [`Core`] => [`Bound`] => [`Normal`]////// Bus devices can automatically implement the dereference hierarchy by using/// [`impl_device_context_deref`].////// Note that the guarantee for a [`Device`] reference to have a certain [`DeviceContext`] comes/// from the specific scope the [`Device`] reference is valid in.////// [`impl_device_context_deref`]: kernel::impl_device_context_derefpub trait DeviceContext: private::Sealed {} /// The [`Normal`] context is the default [`DeviceContext`] of any [`Device`].////// The normal context does not indicate any specific context. Any `Device<Ctx>` is also a valid

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