[PATCH 05/24] rust: driver: make Adapter trait lifetime-parameterized

Danilo Krummrich
2026-04-27T22:12:39Z

Parameterize the Adapter trait with a lifetime, changing the id_info(),
of_id_info() and acpi_id_info() methods to take &'a Device<Bound> and
return &'a Self::IdInfo instead of &'static.

This is needed for the ForLt conversion of bus driver traits. Once
Driver becomes lifetime-parameterized, its IdInfo associated type may
depend on the lifetime parameter. With Adapter<'a>, the impl can set
IdInfo = <F::Of<'a> as Driver<'a>>::IdInfo and the lifetime flows
through naturally, avoiding the need for transmute.

For the current non-lifetime-parameterized Driver trait, this is a no-op
type relaxation; IdInfo is 'static and &'static coerces to &'a.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
rust/kernel/driver.rs | 16 ++++++++++------
rust/kernel/i2c.rs | 10 +++++-----
rust/kernel/platform.rs | 4 ++--
3 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/rust/kernel/driver.rs b/rust/kernel/driver.rs
index 29a67b12c872..91490040d77e 100644
--- a/rust/kernel/driver.rs
+++ b/rust/kernel/driver.rs
@@ -96,7 +96,11 @@

use crate::{
acpi,
- device,
+ device::{
+ self,
+ Bound,
+ Device, //
+ },
of,
prelude::*,
types::{
@@ -192,7 +196,7 @@ extern "C" fn post_unbind_callback(dev: *mut bindings::device) {
// a `struct device`.
//
// INVARIANT: `dev` is valid for the duration of the `post_unbind_callback()`.
- let dev = unsafe { &*dev.cast::<device::Device<device::CoreInternal>>() };
+ let dev = unsafe { &*dev.cast::<Device<device::CoreInternal>>() };

// `remove()` has been completed at this point; devres resources are still valid and will
// be released after the driver's bus device private data is dropped.
@@ -289,7 +293,7 @@ fn init(
/// of a device and a driver.
///
/// It provides bus independent functions for device / driver interactions.
-pub trait Adapter {
+pub trait Adapter<'a> {
/// The type holding driver private data about each device id supported by the driver.
type IdInfo: 'static;

@@ -299,7 +303,7 @@ pub trait Adapter {
/// Returns the driver's private data from the matching entry in the [`acpi::IdTable`], if any.
///
/// If this returns `None`, it means there is no match with an entry in the [`acpi::IdTable`].
- fn acpi_id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
+ fn acpi_id_info(dev: &'a Device<Bound>) -> Option<&'a Self::IdInfo> {
#[cfg(not(CONFIG_ACPI))]
{
let _ = dev;
@@ -333,7 +337,7 @@ fn acpi_id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
/// Returns the driver's private data from the matching entry in the [`of::IdTable`], if any.
///
/// If this returns `None`, it means there is no match with an entry in the [`of::IdTable`].
- fn of_id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
+ fn of_id_info(dev: &'a Device<Bound>) -> Option<&'a Self::IdInfo> {
#[cfg(not(CONFIG_OF))]
{
let _ = dev;
@@ -369,7 +373,7 @@ fn of_id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
///
/// If this returns `None`, it means that there is no match in any of the ID tables directly
/// associated with a [`device::Device`].
- fn id_info(dev: &device::Device) -> Option<&'static Self::IdInfo> {
+ fn id_info(dev: &'a Device<Bound>) -> Option<&'a Self::IdInfo> {
let id = Self::acpi_id_info(dev);
if id.is_some() {
return id;
diff --git a/rust/kernel/i2c.rs b/rust/kernel/i2c.rs
index cde3dd7a6cc7..08d310aa9d6b 100644
--- a/rust/kernel/i2c.rs
+++ b/rust/kernel/i2c.rs
@@ -162,8 +162,8 @@ extern "C" fn probe_callback(idev: *mut bindings::i2c_client) -> kernel::ffi::c_
// INVARIANT: `idev` is valid for the duration of `probe_callback()`.
let idev = unsafe { &*idev.cast::<I2cClient<device::CoreInternal>>() };

- let info =
- Self::i2c_id_info(idev).or_else(|| <Self as driver::Adapter>::id_info(idev.as_ref()));
+ let info = Self::i2c_id_info(idev)
+ .or_else(|| <Self as driver::Adapter<'_>>::id_info(idev.as_ref()));

from_result(|| {
let data = T::probe(idev, info);
@@ -198,14 +198,14 @@ extern "C" fn shutdown_callback(idev: *mut bindings::i2c_client) {
}

/// The [`i2c::IdTable`] of the corresponding driver.
- fn i2c_id_table() -> Option<IdTable<<Self as driver::Adapter>::IdInfo>> {
+ fn i2c_id_table() -> Option<IdTable<<Self as driver::Adapter<'static>>::IdInfo>> {
T::I2C_ID_TABLE
}

/// Returns the driver's private data from the matching entry in the [`i2c::IdTable`], if any.
///
/// If this returns `None`, it means there is no match with an entry in the [`i2c::IdTable`].
- fn i2c_id_info(dev: &I2cClient) -> Option<&'static <Self as driver::Adapter>::IdInfo> {
+ fn i2c_id_info(dev: &I2cClient) -> Option<&'static <Self as driver::Adapter<'static>>::IdInfo> {
let table = Self::i2c_id_table()?;

// SAFETY:
@@ -225,7 +225,7 @@ fn i2c_id_info(dev: &I2cClient) -> Option<&'static <Self as driver::Adapter>::Id
}
}

-impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
+impl<'a, T: Driver + 'static> driver::Adapter<'a> for Adapter<T> {
type IdInfo = T::IdInfo;

fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 7ff69e3eea90..1585b6a1ac45 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -101,7 +101,7 @@ extern "C" fn probe_callback(pdev: *mut bindings::platform_device) -> kernel::ff
//
// INVARIANT: `pdev` is valid for the duration of `probe_callback()`.
let pdev = unsafe { &*pdev.cast::<Device<device::CoreInternal>>() };
- let info = <Self as driver::Adapter>::id_info(pdev.as_ref());
+ let info = <Self as driver::Adapter<'_>>::id_info(pdev.as_ref());

from_result(|| {
let data = T::probe(pdev, info);
@@ -127,7 +127,7 @@ extern "C" fn remove_callback(pdev: *mut bindings::platform_device) {
}
}

-impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
+impl<'a, T: Driver + 'static> driver::Adapter<'a> for Adapter<T> {
type IdInfo = T::IdInfo;

fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
--
2.54.0