From 880dec12a25890e8f5626f04c58d38003f1a5585 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Sat, 21 Jun 2025 21:43:28 +0200 Subject: [PATCH] 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: Benno Lossin Link: https://lore.kernel.org/r/20250621195118.124245-3-dakr@kernel.org [ Improve safety comment as proposed by Benno. - Danilo ] Signed-off-by: Danilo Krummrich --- rust/helpers/device.c | 10 +++++++++ rust/kernel/device.rs | 49 ++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 58 insertions(+), 1 deletion(-) diff --git a/rust/helpers/device.c b/rust/helpers/device.c index 502fef7e9ae8..9a4316bafedf 100644 --- a/rust/helpers/device.c +++ b/rust/helpers/device.c @@ -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); +} diff --git a/rust/kernel/device.rs b/rust/kernel/device.rs index 6b8acee4a378..d527ceef829e 100644 --- a/rust/kernel/device.rs +++ b/rust/kernel/device.rs @@ -6,7 +6,7 @@ use crate::{ bindings, - types::{ARef, Opaque}, + types::{ARef, ForeignOwnable, Opaque}, }; use core::{fmt, marker::PhantomData, ptr}; @@ -62,6 +62,53 @@ impl Device { } } +impl Device { + /// 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(&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(&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 Device { /// Obtain the raw `struct device *`. pub(crate) fn as_raw(&self) -> *mut bindings::device { -- 2.47.2