[PATCH 8/8] samples: rust: auxiliary: illustrate driver interaction

Danilo Krummrich
2025-10-20T22:36:11Z

Illustrate how a parent driver of an auxiliary driver can take advantage
of the device context guarantees given by the auxiliary bus and
subsequently safely derive its device private data.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
---
samples/rust/rust_driver_auxiliary.rs | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/samples/rust/rust_driver_auxiliary.rs b/samples/rust/rust_driver_auxiliary.rs
index a5d67d4d9e83..5761ea314f44 100644
--- a/samples/rust/rust_driver_auxiliary.rs
+++ b/samples/rust/rust_driver_auxiliary.rs
@@ -5,10 +5,17 @@
//! To make this driver probe, QEMU must be run with `-device pci-testdev`.

use kernel::{
- auxiliary, c_str, device::Core, devres::Devres, driver, error::Error, pci, prelude::*,
+ auxiliary, c_str,
+ device::{Bound, Core},
+ devres::Devres,
+ driver,
+ error::Error,
+ pci,
+ prelude::*,
InPlaceModule,
};

+use core::any::TypeId;
use pin_init::PinInit;

const MODULE_NAME: &CStr = <LocalModule as kernel::ModuleMetadata>::NAME;
@@ -43,6 +50,7 @@ fn probe(adev: &auxiliary::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<S

#[pin_data]
struct ParentDriver {
+ private: TypeId,
#[pin]
_reg0: Devres<auxiliary::Registration>,
#[pin]
@@ -63,6 +71,7 @@ impl pci::Driver for ParentDriver {

fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, Error> {
try_pin_init!(Self {
+ private: TypeId::of::<Self>(),
_reg0 <- auxiliary::Registration::new(pdev.as_ref(), AUXILIARY_NAME, 0, MODULE_NAME),
_reg1 <- auxiliary::Registration::new(pdev.as_ref(), AUXILIARY_NAME, 1, MODULE_NAME),
})
@@ -70,9 +79,10 @@ fn probe(pdev: &pci::Device<Core>, _info: &Self::IdInfo) -> impl PinInit<Self, E
}

impl ParentDriver {
- fn connect(adev: &auxiliary::Device) -> Result {
+ fn connect(adev: &auxiliary::Device<Bound>) -> Result {
let dev = adev.parent();
- let pdev: &pci::Device = dev.try_into()?;
+ let pdev: &pci::Device<Bound> = dev.try_into()?;
+ let drvdata = dev.drvdata::<Self>()?;

dev_info!(
dev,
@@ -82,6 +92,12 @@ fn connect(adev: &auxiliary::Device) -> Result {
pdev.device_id()
);

+ dev_info!(
+ dev,
+ "We have access to the private data of {:?}.\n",
+ drvdata.private
+ );
+
Ok(())
}
}
--
2.51.0