Commit e4addc7c authored by Markus Probst's avatar Markus Probst Committed by Danilo Krummrich
Browse files

rust: Add trait to convert a device reference to a bus device reference 



Implement the `AsBusDevice` trait for converting a `Device` reference to a
bus device reference for all bus devices.

The `AsBusDevice` trait allows abstractions to provide the bus device in
class device callbacks. It must not be used by drivers and is intended for
bus and class device abstractions only.

Signed-off-by: default avatarMarkus Probst <markus.probst@posteo.de>
Link: https://patch.msgid.link/20251027200547.1038967-2-markus.probst@posteo.de


[ * Remove unused import.
  * Change visibility of AsBusDevice to public.
  * Fix build for USB.
  * Add impl for I2cClient.
  - Danilo ]
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent 13ae55e2

rust/kernel/auxiliary.rs

+7 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
};

use core::{

    marker::PhantomData,

    mem::offset_of,

    ptr::{addr_of_mut, NonNull},

};
@@ -245,6 +246,12 @@ extern "C" fn release(dev: *mut bindings::device) { 
    }

}



// 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 });

rust/kernel/device.rs

+33 −0
Original line number Diff line number Diff line
@@ -594,6 +594,39 @@ impl DeviceContext for Core {} 
impl DeviceContext for CoreInternal {}

impl DeviceContext for Normal {}



/// Convert device references to bus device references.

///

/// Bus devices can implement this trait to allow abstractions to provide the bus device in

/// class device callbacks.

///

/// This must not be used by drivers and is intended for bus and class device abstractions only.

///

/// # Safety

///

/// `AsBusDevice::OFFSET` must be the offset of the embedded base `struct device` field within a

/// bus device structure.

pub unsafe trait AsBusDevice<Ctx: DeviceContext>: AsRef<Device<Ctx>> {

    /// The relative offset to the device field.

    ///

    /// Use `offset_of!(bindings, field)` macro to avoid breakage.

    const OFFSET: usize;



    /// Convert a reference to [`Device`] into `Self`.

    ///

    /// # Safety

    ///

    /// `dev` must be contained in `Self`.

    unsafe fn from_device(dev: &Device<Ctx>) -> &Self

    where

        Self: Sized,

    {

        let raw = dev.as_raw();

        // SAFETY: `raw - Self::OFFSET` is guaranteed by the safety requirements

        // to be a valid pointer to `Self`.

        unsafe { &*raw.byte_sub(Self::OFFSET).cast::<Self>() }

    }

}



/// # Safety

///

/// The type given as `$device` must be a transparent wrapper of a type that doesn't depend on the

rust/kernel/i2c.rs

+7 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 


use core::{

    marker::PhantomData,

    mem::offset_of,

    ptr::{

        from_ref,

        NonNull, //
@@ -476,6 +477,12 @@ fn as_raw(&self) -> *mut bindings::i2c_client { 
    }

}



// SAFETY: `I2cClient` is a transparent wrapper of `struct i2c_client`.

// The offset is guaranteed to point to a valid device field inside `I2cClient`.

unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for I2cClient<Ctx> {

    const OFFSET: usize = offset_of!(bindings::i2c_client, dev);

}



// SAFETY: `I2cClient` is a transparent wrapper of a type that doesn't depend on

// `I2cClient`'s generic argument.

kernel::impl_device_context_deref!(unsafe { I2cClient });

rust/kernel/pci.rs

+7 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
};

use core::{

    marker::PhantomData,

    mem::offset_of,

    ptr::{

        addr_of_mut,

        NonNull, //
@@ -443,6 +444,12 @@ pub fn set_master(&self) { 
    }

}



// SAFETY: `pci::Device` is a transparent wrapper of `struct pci_dev`.

// The offset is guaranteed to point to a valid device field inside `pci::Device`.

unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for Device<Ctx> {

    const OFFSET: usize = offset_of!(bindings::pci_dev, 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 });

rust/kernel/platform.rs

+7 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 


use core::{

    marker::PhantomData,

    mem::offset_of,

    ptr::{addr_of_mut, NonNull},

};
@@ -287,6 +288,12 @@ pub fn io_request_by_name(&self, name: &CStr) -> Option<IoRequest<'_>> { 
    }

}



// SAFETY: `platform::Device` is a transparent wrapper of `struct platform_device`.

// The offset is guaranteed to point to a valid device field inside `platform::Device`.

unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for Device<Ctx> {

    const OFFSET: usize = offset_of!(bindings::platform_device, dev);

}



macro_rules! define_irq_accessor_by_index {

    (

        $(#[$meta:meta])* $fn_name:ident,