Commit 880dec12 authored by Danilo Krummrich's avatar Danilo Krummrich
Browse files

rust: device: add drvdata accessors 



Implement generic accessors for the private data of a driver bound to a
device.

Those accessors should be used by bus abstractions from their
corresponding core callbacks, such as probe(), remove(), etc.

Implementing them for device::CoreInternal guarantees that driver's can't
interfere with the logic implemented by the bus abstraction.

Acked-by: default avatarBenno Lossin <lossin@kernel.org>
Link: https://lore.kernel.org/r/20250621195118.124245-3-dakr@kernel.org


[ Improve safety comment as proposed by Benno. - Danilo ]
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent fa7486d3

rust/helpers/device.c

+10 −0
Original line number Diff line number Diff line
@@ -15,3 +15,13 @@ int rust_helper_devm_add_action_or_reset(struct device *dev, 
{

	return devm_add_action_or_reset(dev, action, data);

}



void *rust_helper_dev_get_drvdata(const struct device *dev)

{

	return dev_get_drvdata(dev);

}



void rust_helper_dev_set_drvdata(struct device *dev, void *data)

{

	dev_set_drvdata(dev, data);

}

rust/kernel/device.rs

+48 −1
Original line number Diff line number Diff line
@@ -6,7 +6,7 @@ 


use crate::{

    bindings,

    types::{ARef, Opaque},

    types::{ARef, ForeignOwnable, Opaque},

};

use core::{fmt, marker::PhantomData, ptr};
@@ -62,6 +62,53 @@ pub unsafe fn get_device(ptr: *mut bindings::device) -> ARef<Self> { 
    }

}



impl Device<CoreInternal> {

    /// Store a pointer to the bound driver's private data.

    pub fn set_drvdata(&self, data: impl ForeignOwnable) {

        // 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()) }

    }



    /// Take ownership of the private data stored in this [`Device`].

    ///

    /// # Safety

    ///

    /// - Must only be called once after a preceding call to [`Device::set_drvdata`].

    /// - The type `T` must match the type of the `ForeignOwnable` previously stored by

    ///   [`Device::set_drvdata`].

    pub unsafe fn drvdata_obtain<T: ForeignOwnable>(&self) -> 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 { 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

    ///   [`Device::drvdata_obtain`].

    /// - The type `T` must match the type of the `ForeignOwnable` previously stored by

    ///   [`Device::set_drvdata`].

    pub unsafe fn drvdata_borrow<T: ForeignOwnable>(&self) -> T::Borrowed<'_> {

        // 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 { T::borrow(ptr.cast()) }

    }

}



impl<Ctx: DeviceContext> Device<Ctx> {

    /// Obtain the raw `struct device *`.

    pub(crate) fn as_raw(&self) -> *mut bindings::device {