Commit a38dfd60 authored by Danilo Krummrich's avatar Danilo Krummrich
Browse files

rust: platform: impl TryFrom<&Device> for &platform::Device 



Implement TryFrom<&device::Device> for &Device.

This allows us to get a &platform::Device from a generic &Device in a safe
way; the conversion fails if the device' bus type does not match with
the platform bus type.

Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarBenno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20250321214826.140946-4-dakr@kernel.org


[ Support device context types, use dev_is_platform() helper. - Danilo ]
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent a095d0d1

rust/helpers/platform.c

+5 −0
Original line number Diff line number Diff line
@@ -11,3 +11,8 @@ void rust_helper_platform_set_drvdata(struct platform_device *pdev, void *data) 
{

	platform_set_drvdata(pdev, data);

}



bool rust_helper_dev_is_platform(const struct device *dev)

{

	return dev_is_platform(dev);

}

rust/kernel/platform.rs

+21 −1
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ 
//! C header: [`include/linux/platform_device.h`](srctree/include/linux/platform_device.h)



use crate::{

    bindings, device, driver,

    bindings, container_of, device, driver,

    error::{to_result, Result},

    of,

    prelude::*,
@@ -218,6 +218,26 @@ fn as_ref(&self) -> &device::Device<Ctx> { 
    }

}



impl<Ctx: device::DeviceContext> TryFrom<&device::Device<Ctx>> for &Device<Ctx> {

    type Error = kernel::error::Error;



    fn try_from(dev: &device::Device<Ctx>) -> Result<Self, Self::Error> {

        // SAFETY: By the type invariant of `Device`, `dev.as_raw()` is a valid pointer to a

        // `struct device`.

        if !unsafe { bindings::dev_is_platform(dev.as_raw()) } {

            return Err(EINVAL);

        }



        // SAFETY: We've just verified that the bus type of `dev` equals

        // `bindings::platform_bus_type`, hence `dev` must be embedded in a valid

        // `struct platform_device` as guaranteed by the corresponding C code.

        let pdev = unsafe { container_of!(dev.as_raw(), bindings::platform_device, dev) };



        // SAFETY: `pdev` is a valid pointer to a `struct platform_device`.

        Ok(unsafe { &*pdev.cast() })

    }

}



// SAFETY: A `Device` is always reference-counted and can be released from any thread.

unsafe impl Send for Device {}