// SPDX-License-Identifier: GPL-2.0 //! 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, //    },    devres::Devres,    driver,    error::{        from_result,        to_result, //    },    prelude::*,    types::Opaque,    ThisModule, //};use core::{    marker::PhantomData,    mem::offset_of,    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` 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 + 'static> driver::DriverLayout for Adapter<T> {    type DriverType = bindings::auxiliary_driver;    type DriverData = T;    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 + 'static> 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 + 'static> 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>>`.        let data = unsafe { adev.as_ref().drvdata_borrow::<T>() };         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 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(dev: &Device<device::Core>, id_info: &Self::IdInfo) -> impl PinInit<Self, Error>;     /// 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 `Self::drop`.    fn unbind(dev: &Device<device::Core>, this: Pin<&Self>) {        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() }    }} 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 {} /// 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.////// # Invariants////// `self.0` always holds a valid pointer to an initialized and registered/// [`struct auxiliary_device`].pub struct Registration(NonNull<bindings::auxiliary_device>); impl Registration {    /// Create and register a new auxiliary device.    pub fn new<'a>(        parent: &'a device::Device<device::Bound>,        name: &'a CStr,        id: u32,        modname: &'a CStr,    ) -> impl PinInit<Devres<Self>, Error> + 'a {        pin_init::pin_init_scope(move || {            let boxed = KBox::new(Opaque::<bindings::auxiliary_device>::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;            }             // 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: `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(Devres::new(                parent,                // SAFETY: `adev` is guaranteed to be non-null, since the `KBox` was allocated                // successfully.                Self(unsafe { NonNull::new_unchecked(adev) }),            ))        })    }} impl Drop for Registration {    fn drop(&mut self) {        // SAFETY: By the type invariant of `Self`, `self.0.as_ptr()` is a valid registered        // `struct auxiliary_device`.        unsafe { bindings::auxiliary_device_delete(self.0.as_ptr()) };         // This drops the reference we acquired through `auxiliary_device_init()`.        //        // SAFETY: By the type invariant of `Self`, `self.0.as_ptr()` is a valid registered        // `struct auxiliary_device`.        unsafe { bindings::auxiliary_device_uninit(self.0.as_ptr()) };    }} // SAFETY: A `Registration` of a `struct auxiliary_device` can be released from any thread.unsafe impl Send for Registration {} // SAFETY: `Registration` does not expose any methods or fields that need synchronization.unsafe impl Sync for Registration {}