Commit 78418f30 authored by Lyude Paul's avatar Lyude Paul Committed by Greg Kroah-Hartman
Browse files

rust/kernel: Add faux device bindings 



This introduces a module for working with faux devices in rust, along with
adding sample code to show how the API is used. Unlike other types of
devices, we don't provide any hooks for device probe/removal - since these
are optional for the faux API and are unnecessary in rust.

Signed-off-by: default avatarLyude Paul <lyude@redhat.com>
Cc: Maíra Canal <mairacanal@riseup.net>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Acked-by: default avatarDanilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/2025021026-exert-accent-b4c6@gregkh


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 35fa2d88

MAINTAINERS

+2 −0
Original line number Diff line number Diff line
@@ -7116,8 +7116,10 @@ F: rust/kernel/device.rs 
F:	rust/kernel/device_id.rs

F:	rust/kernel/devres.rs

F:	rust/kernel/driver.rs

F:	rust/kernel/faux.rs

F:	rust/kernel/platform.rs

F:	samples/rust/rust_driver_platform.rs

F:	samples/rust/rust_driver_faux.rs









DRIVERS FOR OMAP ADAPTIVE VOLTAGE SCALING (AVS)









M:	Nishanth Menon <nm@ti.com>
































rust/bindings/bindings_helper.h



+1
−0






























Original line number
Diff line number
Diff line







@@ -11,6 +11,7 @@







#include <linux/blk_types.h>









#include <linux/blkdev.h>









#include <linux/cred.h>









#include <linux/device/faux.h>









#include <linux/errname.h>









#include <linux/ethtool.h>









#include <linux/file.h>
































rust/kernel/faux.rs
0 → 100644



+67
−0






























Original line number
Diff line number
Diff line









// SPDX-License-Identifier: GPL-2.0-only



















//! Abstractions for the faux bus.









//!









//! This module provides bindings for working with faux devices in kernel modules.









//!









//! C header: [`include/linux/device/faux.h`]



















use crate::{bindings, device, error::code::*, prelude::*};









use core::ptr::{addr_of_mut, null, null_mut, NonNull};



















/// The registration of a faux device.









///









/// This type represents the registration of a [`struct faux_device`]. When an instance of this type









/// is dropped, its respective faux device will be unregistered from the system.









///









/// # Invariants









///









/// `self.0` always holds a valid pointer to an initialized and registered [`struct faux_device`].









///









/// [`struct faux_device`]: srctree/include/linux/device/faux.h









#[repr(transparent)]









pub struct Registration(NonNull<bindings::faux_device>);



















impl Registration {









    /// Create and register a new faux device with the given name.









    pub fn new(name: &CStr) -> Result<Self> {









        // SAFETY:









        // - `name` is copied by this function into its own storage









        // - `faux_ops` is safe to leave NULL according to the C API









        let dev = unsafe { bindings::faux_device_create(name.as_char_ptr(), null_mut(), null()) };



















        // The above function will return either a valid device, or NULL on failure









        // INVARIANT: The device will remain registered until faux_device_destroy() is called, which









        // happens in our Drop implementation.









        Ok(Self(NonNull::new(dev).ok_or(ENODEV)?))









    }



















    fn as_raw(&self) -> *mut bindings::faux_device {









        self.0.as_ptr()









    }









}



















impl AsRef<device::Device> for Registration {









    fn as_ref(&self) -> &device::Device {









        // SAFETY: The underlying `device` in `faux_device` is guaranteed by the C API to be









        // a valid initialized `device`.









        unsafe { device::Device::as_ref(addr_of_mut!((*self.as_raw()).dev)) }









    }









}



















impl Drop for Registration {









    fn drop(&mut self) {









        // SAFETY: `self.0` is a valid registered faux_device via our type invariants.









        unsafe { bindings::faux_device_destroy(self.as_raw()) }









    }









}



















// SAFETY: The faux device API is thread-safe as guaranteed by the device core, as long as









// faux_device_destroy() is guaranteed to only be called once - which is guaranteed by our type not









// having Copy/Clone.









unsafe impl Send for Registration {}



















// SAFETY: The faux device API is thread-safe as guaranteed by the device core, as long as









// faux_device_destroy() is guaranteed to only be called once - which is guaranteed by our type not









// having Copy/Clone.









unsafe impl Sync for Registration {}
























rust/kernel/lib.rs



+1
−0






























Original line number
Diff line number
Diff line







@@ -46,6 +46,7 @@







pub mod devres;









pub mod driver;









pub mod error;









pub mod faux;









#[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)]









pub mod firmware;









pub mod fs;
































samples/rust/Kconfig



+10
−0






























Original line number
Diff line number
Diff line







@@ -61,6 +61,16 @@ config SAMPLE_RUST_DRIVER_PLATFORM

















	  If unsure, say N.



















config SAMPLE_RUST_DRIVER_FAUX









	tristate "Faux Driver"









	help









	  This option builds the Rust Faux driver sample.



















	  To compile this as a module, choose M here:









	  the module will be called rust_driver_faux.



















	  If unsure, say N.



















config SAMPLE_RUST_HOSTPROGS









	bool "Host programs"









	help