[PATCH v6 3/4] rust: add basic serial device bus abstractions

Markus Probst via B4 Relay
2026-04-27T18:05:51Z

Implement the basic serial device bus abstractions required to write a
serial device bus device driver with or without the need for initial device
data. This includes the following data structures:

The `serdev::Driver` trait represents the interface to the driver.

The `serdev::Device` abstraction represents a `struct serdev_device`.

In order to provide the Serdev specific parts to a generic
`driver::Registration` the `driver::RegistrationOps` trait is
implemented by `serdev::Adapter`.

Signed-off-by: Markus Probst <markus.probst@posteo.de>
---
drivers/tty/serdev/Kconfig | 7 +
rust/bindings/bindings_helper.h | 1 +
rust/helpers/helpers.c | 1 +
rust/helpers/serdev.c | 22 ++
rust/kernel/lib.rs | 2 +
rust/kernel/serdev.rs | 536 ++++++++++++++++++++++++++++++++++++++++
6 files changed, 569 insertions(+)

diff --git a/drivers/tty/serdev/Kconfig b/drivers/tty/serdev/Kconfig
index 46ae732bfc68..e6dfe949ad01 100644
--- a/drivers/tty/serdev/Kconfig
+++ b/drivers/tty/serdev/Kconfig
@@ -9,6 +9,13 @@ menuconfig SERIAL_DEV_BUS

Note that you typically also want to enable TTY port controller support.

+config RUST_SERIAL_DEV_BUS_ABSTRACTIONS
+ bool "Rust Serial device bus abstractions"
+ depends on RUST
+ select SERIAL_DEV_BUS
+ help
+ This enables the Rust abstraction for the serial device bus API.
+
if SERIAL_DEV_BUS

config SERIAL_DEV_CTRL_TTYPORT
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 446dbeaf0866..4e42635b8607 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -84,6 +84,7 @@
#include <linux/regulator/consumer.h>
#include <linux/sched.h>
#include <linux/security.h>
+#include <linux/serdev.h>
#include <linux/slab.h>
#include <linux/sys_soc.h>
#include <linux/task_work.h>
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index 625921e27dfb..de14ef55029f 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -85,6 +85,7 @@
#include "regulator.c"
#include "scatterlist.c"
#include "security.c"
+#include "serdev.c"
#include "signal.c"
#include "slab.c"
#include "spinlock.c"
diff --git a/rust/helpers/serdev.c b/rust/helpers/serdev.c
new file mode 100644
index 000000000000..c52b78ca3fc7
--- /dev/null
+++ b/rust/helpers/serdev.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/serdev.h>
+
+__rust_helper
+void rust_helper_serdev_device_driver_unregister(struct serdev_device_driver *sdrv)
+{
+ serdev_device_driver_unregister(sdrv);
+}
+
+__rust_helper
+void rust_helper_serdev_device_put(struct serdev_device *serdev)
+{
+ serdev_device_put(serdev);
+}
+
+__rust_helper
+void rust_helper_serdev_device_set_client_ops(struct serdev_device *serdev,
+ const struct serdev_device_ops *ops)
+{
+ serdev_device_set_client_ops(serdev, ops);
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index b72b2fbe046d..83bc2c312241 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -118,6 +118,8 @@
pub mod scatterlist;
pub mod security;
pub mod seq_file;
+#[cfg(CONFIG_RUST_SERIAL_DEV_BUS_ABSTRACTIONS)]
+pub mod serdev;
pub mod sizes;
#[cfg(CONFIG_SOC_BUS)]
pub mod soc;
diff --git a/rust/kernel/serdev.rs b/rust/kernel/serdev.rs
new file mode 100644
index 000000000000..d9dc0862bc88
--- /dev/null
+++ b/rust/kernel/serdev.rs
@@ -0,0 +1,536 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Abstractions for the serial device bus.
+//!
+//! C header: [`include/linux/serdev.h`](srctree/include/linux/serdev.h)
+
+use crate::{
+ acpi,
+ device,
+ devres,
+ driver,
+ error::{
+ from_result,
+ to_result,
+ VTABLE_DEFAULT_ERROR, //
+ },
+ of,
+ prelude::*,
+ sync::{
+ aref::AlwaysRefCounted,
+ Completion, //
+ },
+ time::{
+ msecs_to_jiffies,
+ Jiffies,
+ Msecs, //
+ },
+ types::Opaque, //
+};
+
+use core::{
+ cell::UnsafeCell,
+ marker::PhantomData,
+ mem::offset_of,
+ num::NonZero,
+ ptr::NonNull, //
+};
+
+/// Parity bit to use with a serial device.
+#[repr(u32)]
+pub enum Parity {
+ /// No parity bit.
+ None = bindings::serdev_parity_SERDEV_PARITY_NONE,
+ /// Even partiy.
+ Even = bindings::serdev_parity_SERDEV_PARITY_EVEN,
+ /// Odd parity.
+ Odd = bindings::serdev_parity_SERDEV_PARITY_ODD,
+}
+
+/// Timeout in Jiffies.
+pub enum Timeout {
+ /// Wait for a specific amount of [`Jiffies`].
+ Jiffies(NonZero<Jiffies>),
+ /// Wait for a specific amount of [`Msecs`].
+ Milliseconds(NonZero<Msecs>),
+ /// Wait as long as possible.
+ ///
+ /// This is equivalent to [`kernel::task::MAX_SCHEDULE_TIMEOUT`].
+ Max,
+}
+
+impl Timeout {
+ fn into_jiffies(self) -> isize {
+ match self {
+ Self::Jiffies(value) => value.get().try_into().unwrap_or_default(),
+ Self::Milliseconds(value) => {
+ msecs_to_jiffies(value.get()).try_into().unwrap_or_default()
+ }
+ Self::Max => 0,
+ }
+ }
+}
+
+/// An adapter for the registration of serial device bus device drivers.
+pub struct Adapter<T: Driver>(T);
+
+// SAFETY:
+// - `bindings::serdev_device_driver` is a C type declared as `repr(C)`.
+// - `Drvdata<T>` is the type of the driver's device private data.
+// - `struct serdev_device_driver` embeds a `struct device_driver`.
+// - `DEVICE_DRIVER_OFFSET` is the correct byte offset to the embedded `struct device_driver`.
+unsafe impl<T: Driver + 'static> driver::DriverLayout for Adapter<T> {
+ type DriverType = bindings::serdev_device_driver;
+ type DriverData = T;
+ const DEVICE_DRIVER_OFFSET: usize = core::mem::offset_of!(Self::DriverType, driver);
+}
+
+// SAFETY: A call to `unregister` for a given instance of `DriverType` is guaranteed to be valid if
+// a preceding call to `register` has been successful.
+unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+ unsafe fn register(
+ sdrv: &Opaque<Self::DriverType>,
+ name: &'static CStr,
+ module: &'static ThisModule,
+ ) -> Result {
+ let of_table = match T::OF_ID_TABLE {
+ Some(table) => table.as_ptr(),
+ None => core::ptr::null(),
+ };
+
+ let acpi_table = match T::ACPI_ID_TABLE {
+ Some(table) => table.as_ptr(),
+ None => core::ptr::null(),
+ };
+
+ // SAFETY: It's safe to set the fields of `struct serdev_device_driver` on initialization.
+ unsafe {
+ (*sdrv.get()).driver.name = name.as_char_ptr();
+ (*sdrv.get()).probe = Some(Self::probe_callback);
+ (*sdrv.get()).remove = Some(Self::remove_callback);
+ (*sdrv.get()).driver.of_match_table = of_table;
+ (*sdrv.get()).driver.acpi_match_table = acpi_table;
+ }
+
+ // SAFETY: `sdrv` is guaranteed to be a valid `DriverType`.
+ to_result(unsafe { bindings::__serdev_device_driver_register(sdrv.get(), module.0) })
+ }
+
+ unsafe fn unregister(sdrv: &Opaque<Self::DriverType>) {
+ // SAFETY: `sdrv` is guaranteed to be a valid `DriverType`.
+ unsafe { bindings::serdev_device_driver_unregister(sdrv.get()) };
+ }
+}
+
+#[pin_data]
+struct PrivateData {
+ #[pin]
+ probe_complete: Completion,
+ error: UnsafeCell<bool>,
+}
+
+impl<T: Driver + 'static> Adapter<T> {
+ const OPS: &'static bindings::serdev_device_ops = &bindings::serdev_device_ops {
+ receive_buf: if T::HAS_RECEIVE {
+ Some(Self::receive_buf_callback)
+ } else {
+ None
+ },
+ write_wakeup: Some(bindings::serdev_device_write_wakeup),
+ };
+
+ extern "C" fn probe_callback(sdev: *mut bindings::serdev_device) -> kernel::ffi::c_int {
+ // SAFETY: The serial device bus only ever calls the probe callback with a valid pointer to
+ // a `struct serdev_device`.
+ //
+ // INVARIANT: `sdev` is valid for the duration of `probe_callback()`.
+ let sdev = unsafe { &*sdev.cast::<Device<device::CoreInternal>>() };
+ let id_info = <Self as driver::Adapter>::id_info(sdev.as_ref());
+
+ from_result(|| {
+ let private_data = devres::register(
+ sdev.as_ref(),
+ try_pin_init!(PrivateData {
+ probe_complete <- Completion::new(),
+ error: false.into(),
+ }),
+ GFP_KERNEL,
+ )?;
+
+ // SAFETY: `sdev.as_raw()` is guaranteed to be a valid pointer to `serdev_device`.
+ unsafe {
+ (*sdev.as_raw()).rust_private_data =
+ (&raw const *private_data).cast::<c_void>().cast_mut()
+ };
+
+ // SAFETY: `sdev.as_raw()` is guaranteed to be a valid pointer to `serdev_device`.
+ unsafe { bindings::serdev_device_set_client_ops(sdev.as_raw(), Self::OPS) };
+
+ // SAFETY: The serial device bus only ever calls the probe callback with a valid pointer
+ // to a `serdev_device`.
+ to_result(unsafe {
+ bindings::devm_serdev_device_open(sdev.as_ref().as_raw(), sdev.as_raw())
+ })?;
+
+ let data = T::probe(sdev, id_info);
+ let result = sdev.as_ref().set_drvdata(data);
+
+ // SAFETY: We have exclusive access to `private_data.error`.
+ unsafe { *private_data.error.get() = result.is_err() };
+
+ private_data.probe_complete.complete_all();
+
+ result.map(|()| 0)
+ })
+ }
+
+ extern "C" fn remove_callback(sdev: *mut bindings::serdev_device) {
+ // SAFETY: The serial device bus only ever calls the remove callback with a valid pointer
+ // to a `struct serdev_device`.
+ //
+ // INVARIANT: `sdev` is valid for the duration of `remove_callback()`.
+ let sdev = unsafe { &*sdev.cast::<Device<device::CoreInternal>>() };
+
+ // SAFETY: `remove_callback` is only ever called after a successful call to
+ // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
+ // and stored a `Pin<KBox<T>>`.
+ let data = unsafe { sdev.as_ref().drvdata_borrow::<T>() };
+
+ T::unbind(sdev, data);
+ }
+
+ extern "C" fn receive_buf_callback(
+ sdev: *mut bindings::serdev_device,
+ buf: *const u8,
+ length: usize,
+ ) -> usize {
+ // SAFETY: The serial device bus only ever calls the receive buf callback with a valid
+ // pointer to a `struct serdev_device`.
+ //
+ // INVARIANT: `sdev` is valid for the duration of `receive_buf_callback()`.
+ let sdev = unsafe { &*sdev.cast::<Device<device::CoreInternal>>() };
+
+ // SAFETY:
+ // - The serial device bus only ever calls the receive buf callback with a valid pointer to
+ // a `struct serdev_device`.
+ // - `receive_buf_callback` is only ever called after a successful call to
+ // `probe_callback`, hence it's guaranteed that `sdev.private_data` is a pointer
+ // to a valid `PrivateData`.
+ let private_data = unsafe { &*(*sdev.as_raw()).rust_private_data.cast::<PrivateData>() };
+
+ private_data.probe_complete.wait_for_completion();
+
+ // SAFETY: No one has exclusive access to `private_data.error`.
+ if unsafe { *private_data.error.get() } {
+ return length;
+ }
+
+ // SAFETY: `receive_buf_callback` is only ever called after a successful call to
+ // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
+ // and stored a `Pin<KBox<T>>`.
+ let data = unsafe { sdev.as_ref().drvdata_borrow::<T>() };
+
+ // SAFETY: `buf` is guaranteed to be non-null and has the size of `length`.
+ let buf = unsafe { core::slice::from_raw_parts(buf, length) };
+
+ T::receive(sdev, data, buf)
+ }
+}
+
+impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
+ type IdInfo = T::IdInfo;
+
+ fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
+ T::OF_ID_TABLE
+ }
+
+ fn acpi_id_table() -> Option<acpi::IdTable<Self::IdInfo>> {
+ T::ACPI_ID_TABLE
+ }
+}
+
+/// Declares a kernel module that exposes a single serial device bus device driver.
+///
+/// # Examples
+///
+/// ```ignore
+/// kernel::module_serdev_device_driver! {
+/// type: MyDriver,
+/// name: "Module name",
+/// authors: ["Author name"],
+/// description: "Description",
+/// license: "GPL v2",
+/// }
+/// ```
+#[macro_export]
+macro_rules! module_serdev_device_driver {
+ ($($f:tt)*) => {
+ $crate::module_driver!(<T>, $crate::serdev::Adapter<T>, { $($f)* });
+ };
+}
+
+/// The serial device bus device driver trait.
+///
+/// Drivers must implement this trait in order to get a serial device bus device driver registered.
+///
+/// # Examples
+///
+///```
+/// # use kernel::{
+/// acpi,
+/// bindings,
+/// device::{
+/// Bound,
+/// Core, //
+/// },
+/// of,
+/// serdev, //
+/// };
+///
+/// struct MyDriver;
+///
+/// kernel::of_device_table!(
+/// OF_TABLE,
+/// MODULE_OF_TABLE,
+/// <MyDriver as serdev::Driver>::IdInfo,
+/// [
+/// (of::DeviceId::new(c"test,device"), ())
+/// ]
+/// );
+///
+/// kernel::acpi_device_table!(
+/// ACPI_TABLE,
+/// MODULE_ACPI_TABLE,
+/// <MyDriver as serdev::Driver>::IdInfo,
+/// [
+/// (acpi::DeviceId::new(c"LNUXBEEF"), ())
+/// ]
+/// );
+///
+/// #[vtable]
+/// impl serdev::Driver for MyDriver {
+/// type IdInfo = ();
+/// const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
+/// const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
+///
+/// fn probe(
+/// sdev: &serdev::Device<Core>,
+/// _id_info: Option<&Self::IdInfo>,
+/// ) -> impl PinInit<Self, Error> {
+/// sdev.set_baudrate(115200);
+/// sdev.write_all(b"Hello\n", serdev::Timeout::Max)?;
+/// Ok(MyDriver)
+/// }
+/// }
+///```
+#[vtable]
+pub trait Driver: Send {
+ /// The type holding driver private data about each device id supported by the driver.
+ // TODO: Use associated_type_defaults once stabilized:
+ //
+ // ```
+ // type IdInfo: 'static = ();
+ // ```
+ type IdInfo: 'static;
+
+ /// The table of OF device ids supported by the driver.
+ const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;
+
+ /// The table of ACPI device ids supported by the driver.
+ const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = None;
+
+ /// Serial device bus device driver probe.
+ ///
+ /// Called when a new serial device bus device is added or discovered.
+ /// Implementers should attempt to initialize the device here.
+ fn probe(
+ sdev: &Device<device::Core>,
+ id_info: Option<&Self::IdInfo>,
+ ) -> impl PinInit<Self, Error>;
+
+ /// Serial device bus device driver unbind.
+ ///
+ /// Called when a [`Device`] is unbound from its bound [`Driver`]. Implementing this callback
+ /// is optional.
+ ///
+ /// This callback serves as a place for drivers to perform teardown operations that require a
+ /// `&Device<Core>` or `&Device<Bound>` reference. For instance.
+ ///
+ /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
+ fn unbind(sdev: &Device<device::Core>, this: Pin<&Self>) {
+ let _ = (sdev, this);
+ }
+
+ /// Serial device bus device data receive callback.
+ ///
+ /// Called when data got received from device.
+ ///
+ /// Returns the number of bytes accepted.
+ fn receive(sdev: &Device<device::Bound>, this: Pin<&Self>, data: &[u8]) -> usize {
+ let _ = (sdev, this, data);
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+}
+
+/// The serial device bus device representation.
+///
+/// This structure represents the Rust abstraction for a C `struct serdev_device`. The
+/// implementation abstracts the usage of an already existing C `struct serdev_device` within Rust
+/// code that we get passed from the C side.
+///
+/// # Invariants
+///
+/// A [`Device`] instance represents a valid `struct serdev_device` created by the C portion of
+/// the kernel.
+#[repr(transparent)]
+pub struct Device<Ctx: device::DeviceContext = device::Normal>(
+ Opaque<bindings::serdev_device>,
+ PhantomData<Ctx>,
+);
+
+impl<Ctx: device::DeviceContext> Device<Ctx> {
+ fn as_raw(&self) -> *mut bindings::serdev_device {
+ self.0.get()
+ }
+}
+
+impl Device<device::Bound> {
+ /// Set the baudrate in bits per second.
+ ///
+ /// Common baudrates are 115200, 9600, 19200, 57600, 4800.
+ ///
+ /// Use [`Device::write_flush`] before calling this if you have written data prior to this call.
+ pub fn set_baudrate(&self, speed: u32) -> Result<(), u32> {
+ // SAFETY: `self.as_raw()` is guaranteed to be a pointer to a valid `serdev_device`.
+ let ret = unsafe { bindings::serdev_device_set_baudrate(self.as_raw(), speed) };
+ if ret == speed {
+ Ok(())
+ } else {
+ Err(ret)
+ }
+ }
+
+ /// Set if flow control should be enabled.
+ ///
+ /// Use [`Device::write_flush`] before calling this if you have written data prior to this call.
+ pub fn set_flow_control(&self, enable: bool) {
+ // SAFETY: `self.as_raw()` is guaranteed to be a pointer to a valid `serdev_device`.
+ unsafe { bindings::serdev_device_set_flow_control(self.as_raw(), enable) };
+ }
+
+ /// Set parity to use.
+ ///
+ /// Use [`Device::write_flush`] before calling this if you have written data prior to this call.
+ pub fn set_parity(&self, parity: Parity) -> Result {
+ // SAFETY: `self.as_raw()` is guaranteed to be a pointer to a valid `serdev_device`.
+ to_result(unsafe { bindings::serdev_device_set_parity(self.as_raw(), parity as u32) })
+ }
+
+ /// Write data to the serial device until the controller has accepted all the data or has
+ /// been interrupted by a timeout or signal.
+ ///
+ /// Note that any accepted data has only been buffered by the controller. Use
+ /// [`Device::wait_until_sent`] to make sure the controller write buffer has actually been
+ /// emptied.
+ ///
+ /// Returns the number of bytes written (less than `data.len()` if interrupted).
+ /// [`kernel::error::code::ETIMEDOUT`] or [`kernel::error::code::ERESTARTSYS`] if interrupted
+ /// before any bytes were written.
+ pub fn write_all(&self, data: &[u8], timeout: Timeout) -> Result<usize> {
+ // SAFETY:
+ // - `self.as_raw()` is guaranteed to be a pointer to a valid `serdev_device`.
+ // - `data.as_ptr()` is guaranteed to be a valid array pointer with the size of
+ // `data.len()`.
+ let ret = unsafe {
+ bindings::serdev_device_write(
+ self.as_raw(),
+ data.as_ptr(),
+ data.len(),
+ timeout.into_jiffies(),
+ )
+ };
+ // CAST: negative return values are guaranteed to be between `-MAX_ERRNO` and `-1`,
+ // which always fit into a `i32`.
+ to_result(ret as i32).map(|()| ret.unsigned_abs())
+ }
+
+ /// Write data to the serial device.
+ ///
+ /// If you want to write until the controller has accepted all the data, use
+ /// [`Device::write_all`].
+ ///
+ /// Note that any accepted data has only been buffered by the controller. Use
+ /// [ Device::wait_until_sent`] to make sure the controller write buffer has actually been
+ /// emptied.
+ ///
+ /// Returns the number of bytes written (less than `data.len()` if not enough room in the
+ /// write buffer).
+ pub fn write(&self, data: &[u8]) -> Result<u32> {
+ // SAFETY:
+ // - `self.as_raw()` is guaranteed to be a pointer to a valid `serdev_device`.
+ // - `data.as_ptr()` is guaranteed to be a valid array pointer with the size of
+ // `data.len()`.
+ let ret =
+ unsafe { bindings::serdev_device_write_buf(self.as_raw(), data.as_ptr(), data.len()) };
+
+ to_result(ret as i32).map(|()| ret.unsigned_abs())
+ }
+
+ /// Send data to the serial device immediately.
+ ///
+ /// Note that this doesn't guarantee that the data has been transmitted.
+ /// Use [`Device::wait_until_sent`] for this purpose.
+ pub fn write_flush(&self) {
+ // SAFETY: `self.as_raw()` is guaranteed to be a pointer to a valid `serdev_device`.
+ unsafe { bindings::serdev_device_write_flush(self.as_raw()) };
+ }
+
+ /// Wait for the data to be sent.
+ ///
+ /// After this function, the write buffer of the controller should be empty.
+ pub fn wait_until_sent(&self, timeout: Timeout) {
+ // SAFETY: `self.as_raw()` is guaranteed to be a pointer to a valid `serdev_device`.
+ unsafe { bindings::serdev_device_wait_until_sent(self.as_raw(), timeout.into_jiffies()) };
+ }
+}
+
+// SAFETY: `serdev::Device` is a transparent wrapper of `struct serdev_device`.
+// The offset is guaranteed to point to a valid device field inside `serdev::Device`.
+unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for Device<Ctx> {
+ const OFFSET: usize = offset_of!(bindings::serdev_device, dev);
+}
+
+// SAFETY: `Device` is a transparent wrapper of a type that doesn't depend on `Device`'s generic
+// argument.
+kernel::impl_device_context_deref!(unsafe { Device });
+kernel::impl_device_context_into_aref!(Device);
+
+// SAFETY: Instances of `Device` are always reference-counted.
+unsafe impl AlwaysRefCounted for Device {
+ fn inc_ref(&self) {
+ self.as_ref().inc_ref();
+ }
+
+ unsafe fn dec_ref(obj: NonNull<Self>) {
+ // SAFETY: The safety requirements guarantee that the refcount is non-zero.
+ unsafe { bindings::serdev_device_put(obj.cast().as_ptr()) }
+ }
+}
+
+impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for Device<Ctx> {
+ fn as_ref(&self) -> &device::Device<Ctx> {
+ // SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid
+ // `struct serdev_device`.
+ let dev = unsafe { &raw mut (*self.as_raw()).dev };
+
+ // SAFETY: `dev` points to a valid `struct device`.
+ unsafe { device::Device::from_raw(dev) }
+ }
+}
+
+// SAFETY: A `Device` is always reference-counted and can be released from any thread.
+unsafe impl Send for Device {}
+
+// SAFETY: `Device` can be shared among threads because all methods of `Device`
+// (i.e. `Device<Normal>) are thread safe.
+unsafe impl Sync for Device {}

--
2.53.0