[PATCH v4 0/2] rust: input: add input/serio abstractions and port Gravis Stinger driver

[PATCH v4 0/2] rust: input: add input/serio abstractions and port Gravis Stinger driver

[clicedvly768]

This patch series introduces safe Rust abstractions for Linux input
devices (struct input_dev) and the serio (Serial I/O) bus subsystem,
along with a port of the legacy Gravis Stinger serial gamepad driver
to safe Rust.

Changes in v4:
  - Makefile: restored analog.o and db9.o in joystick Makefile
    that were inadvertently removed during previous revisions.
  - serio: eliminated concurrent borrow_mut() and aliasing data races
    between connect_callback() and interrupt_callback() by initializing
    and registering the input device prior to serio_open(), removing
    the problematic start() hook.
  - serio: mapped interrupt return codes via bindings::irqreturn_t(..)
    without referencing missing bindings constants.
  - serio & stinger: formatted all module imports in strict vertical
    style with trailing // comments.
  - serio: annotated Registration::drop() and Driver::disconnect() with
    #[inline].

Changes in v3:
  - input: added AllocatedDevice::set_phys_from_parent() to dynamically
    format the physical device path ("%s/input0") in an owned kernel
    heap buffer.
  - input: managed parent device reference counts in set_parent(), drop(),
    and register() using get_device()/put_device() to avoid dangling
    pointers and reference leaks.
  - input: eliminated manual cleanup duplication in register() by checking
    to_result() before mem::forget(self).
  - input: implemented Send and Sync for AllocatedDevice, added #[inline]
    on small methods, and formatted imports vertically.
  - serio: integrated serio::Device with kernel device abstractions via
    AsBusDevice, impl_device_context_deref!, and as_device().
  - stinger: restored userspace-visible device name ("Gravis Stinger")
    and dynamic phys path, preserving udev and EVIOCGNAME compatibility.
  - stinger: maintained module name "stinger.ko" using Kbuild object
    aliasing under CONFIG_JOYSTICK_STINGER_RUST.

Changes in v2:
  - Combined serio subsystem abstractions and Gravis Stinger driver
    port into a single patch (2/2).
  - Retained original C driver (stinger.c) under CONFIG_JOYSTICK_STINGER
    and introduced CONFIG_JOYSTICK_STINGER_RUST to avoid regressions on
    architectures and configurations without Rust support.
  - Ensured IS_REACHABLE() guards for C helpers and #[cfg(CONFIG_* = "y")]
    for rust/kernel modules to prevent unresolved symbols.

clicedvly768 (2):
  rust: input: add input device abstractions
  rust: serio: add serio bus abstractions and port Gravis Stinger driver

 drivers/input/joystick/Kconfig         |  14 ++
 drivers/input/joystick/Makefile        |   3 +
 drivers/input/joystick/stinger_rust.rs | 184 +++++++++++++++
 rust/bindings/bindings_helper.h        |   2 +
 rust/helpers/helpers.c                 |   2 +
 rust/helpers/input.c                   |  22 ++
 rust/helpers/serio.c                   |  17 ++
 rust/kernel/input.rs                   | 253 ++++++++++++++++++++
 rust/kernel/lib.rs                     |   4 +
 rust/kernel/serio.rs                   | 306 +++++++++++++++++++++++++
 10 files changed, 807 insertions(+)
 create mode 100644 drivers/input/joystick/stinger_rust.rs
 create mode 100644 rust/helpers/input.c
 create mode 100644 rust/helpers/serio.c
 create mode 100644 rust/kernel/input.rs
 create mode 100644 rust/kernel/serio.rs

-- 
2.56.0

[PATCH v4 1/2] rust: input: add input device abstractions

[clicedvly768]

Add safe Rust abstractions for Linux input devices (struct input_dev).

This provides:
- `AllocatedDevice`: a newly allocated, unregistered input device handle
  that allows configuring capabilities (keys, absolute axis limits, parent
  device) before registration.
- Safe string methods: `set_name` and `set_phys` accept `&'static CStr`
  to prevent use-after-free since the input core does not copy strings.
- `set_phys_from_parent`: dynamic physical location path formatting
  ("%s/input0") stored safely in an owned kernel heap buffer.
- Device lifecycle and reference count management: `set_parent` takes
  a reference count via `bindings::get_device` to avoid dangling pointers,
  releasing it appropriately on drop or post-registration.
- Bounds-checked `set_abs_params` validating `axis < ABS_CNT` (0x40)
  to prevent memory corruption in `dev->absinfo`.
- `RegisteredDevice`: a registered input device handle providing safe,
  inlined methods to report keys, absolute coordinates, and synchronization
  events. Automatically calls `input_unregister_device` on drop (RAII).
- Constants for bus types (`bus::*`) and event types (`event_type::*`).
- Alphabetically sorted imports and module entries gated with
  `#[cfg(CONFIG_INPUT = "y")]` and `#if IS_REACHABLE(CONFIG_INPUT)`
  to avoid link failures when CONFIG_INPUT is disabled or modular.

Signed-off-by: clicedvly768 <harepro29@gmail.com>
---
 rust/bindings/bindings_helper.h |   1 +
 rust/helpers/helpers.c          |   1 +
 rust/helpers/input.c            |  22 +++
 rust/kernel/input.rs            | 253 ++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs              |   2 +
 5 files changed, 279 insertions(+)
 create mode 100644 rust/helpers/input.c
 create mode 100644 rust/kernel/input.rs

diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 3791af0aadc7..4b09d3980e10 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -64,6 +64,7 @@
 #include <linux/fwctl.h>
 #include <linux/fs.h>
 #include <linux/i2c.h>
+#include <linux/input.h>
 #include <linux/interrupt.h>
 #include <linux/io-pgtable.h>
 #include <linux/ioport.h>
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index d62c7be1ca7b..77cec85ad153 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -67,6 +67,7 @@
 #include "fs.c"
 #include "fwctl.c"
 #include "gpu.c"
+#include "input.c"
 #include "interrupt.c"
 #include "io.c"
 #include "irq.c"
diff --git a/rust/helpers/input.c b/rust/helpers/input.c
new file mode 100644
index 000000000000..f43a06acfdc3
--- /dev/null
+++ b/rust/helpers/input.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/input.h>
+
+#if IS_REACHABLE(CONFIG_INPUT)
+
+__rust_helper void rust_helper_input_report_key(struct input_dev *dev, unsigned int code, int value)
+{
+	input_report_key(dev, code, value);
+}
+
+__rust_helper void rust_helper_input_report_abs(struct input_dev *dev, unsigned int code, int value)
+{
+	input_report_abs(dev, code, value);
+}
+
+__rust_helper void rust_helper_input_sync(struct input_dev *dev)
+{
+	input_sync(dev);
+}
+
+#endif /* IS_REACHABLE(CONFIG_INPUT) */
diff --git a/rust/kernel/input.rs b/rust/kernel/input.rs
new file mode 100644
index 000000000000..14977298ad47
--- /dev/null
+++ b/rust/kernel/input.rs
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Input subsystem abstractions for safe Rust drivers.
+//!
+//! Provides a safe Rust object-oriented interface around Linux `struct input_dev`,
+//! ensuring safe allocation, capability configuration, registration, and RAII cleanup.
+
+use crate::{
+    bindings,         //
+    device,           //
+    error::to_result, //
+    prelude::*,       //
+};
+use core::ptr::NonNull;
+
+/// Bus types for input devices.
+pub mod bus {
+    use super::*;
+
+    /// PCI bus.
+    pub const PCI: u16 = bindings::BUS_PCI as u16;
+    /// USB bus.
+    pub const USB: u16 = bindings::BUS_USB as u16;
+    /// RS232 serial bus.
+    pub const RS232: u16 = bindings::BUS_RS232 as u16;
+}
+
+/// Event types reported by input devices.
+pub mod event_type {
+    use super::*;
+
+    /// Key or button press/release events.
+    pub const KEY: u32 = bindings::EV_KEY;
+    /// Absolute axis movement events.
+    pub const ABS: u32 = bindings::EV_ABS;
+}
+
+/// An allocated input device being configured prior to registration.
+pub struct AllocatedDevice {
+    ptr: NonNull<bindings::input_dev>,
+    phys: Option<KBox<[u8; 64]>>,
+}
+
+impl AllocatedDevice {
+    /// Allocates a new input device.
+    #[inline]
+    pub fn new() -> Result<Self> {
+        // SAFETY: `input_allocate_device` returns either a valid pointer or NULL.
+        let ptr = unsafe { bindings::input_allocate_device() };
+        let ptr = NonNull::new(ptr).ok_or(ENOMEM)?;
+
+        Ok(Self { ptr, phys: None })
+    }
+
+    /// Sets the human-readable device name.
+    #[inline]
+    pub fn set_name(&mut self, name: &'static CStr) {
+        // SAFETY: `self.ptr` is valid and `name` has static lifetime.
+        unsafe {
+            (*self.ptr.as_ptr()).name = name.as_char_ptr().cast();
+        }
+    }
+
+    /// Sets the physical location string from a static C string.
+    #[inline]
+    pub fn set_phys(&mut self, phys: &'static CStr) {
+        // SAFETY: `self.ptr` is valid and `phys` has static lifetime.
+        unsafe {
+            (*self.ptr.as_ptr()).phys = phys.as_char_ptr().cast();
+        }
+    }
+
+    /// Sets the physical location string by formatting `<parent_phys>/input0`.
+    #[inline]
+    pub fn set_phys_from_parent(&mut self, parent_phys: &[u8]) -> Result {
+        let mut buf = KBox::new([0u8; 64], GFP_KERNEL)?;
+        let len = parent_phys
+            .iter()
+            .position(|&b| b == 0)
+            .unwrap_or(parent_phys.len());
+        let suffix = b"/input0\0";
+        if len + suffix.len() > buf.len() {
+            return Err(EINVAL);
+        }
+        buf[..len].copy_from_slice(&parent_phys[..len]);
+        buf[len..len + suffix.len()].copy_from_slice(suffix);
+
+        // SAFETY: `buf` is allocated on the kernel heap and its lifetime is tied to `self.phys`.
+        unsafe {
+            (*self.ptr.as_ptr()).phys = buf.as_ptr().cast();
+        }
+        self.phys = Some(buf);
+        Ok(())
+    }
+
+    /// Sets device identifier (bus type, vendor, product, version).
+    #[inline]
+    pub fn set_id(&mut self, bustype: u16, vendor: u16, product: u16, version: u16) {
+        // SAFETY: `self.ptr` is valid.
+        unsafe {
+            let dev = self.ptr.as_ptr();
+            (*dev).id.bustype = bustype;
+            (*dev).id.vendor = vendor;
+            (*dev).id.product = product;
+            (*dev).id.version = version;
+        }
+    }
+
+    /// Sets the parent device for this input device.
+    ///
+    /// Holds a reference count on `parent` to prevent dangling pointers before registration.
+    #[inline]
+    pub fn set_parent(&mut self, parent: &device::Device) {
+        // SAFETY: `self.ptr` is valid, and `parent.as_raw()` returns a valid `struct device`.
+        // Acquire a reference to guarantee `parent` remains alive while referenced by `dev.parent`.
+        unsafe {
+            let old = (*self.ptr.as_ptr()).dev.parent;
+            if !old.is_null() {
+                bindings::put_device(old);
+            }
+            (*self.ptr.as_ptr()).dev.parent = bindings::get_device(parent.as_raw());
+        }
+    }
+
+    /// Enables support for a capability (e.g. key or axis).
+    #[inline]
+    pub fn set_capability(&mut self, type_: u32, code: u32) {
+        // SAFETY: `self.ptr` is valid and type/code are valid capability values.
+        unsafe {
+            bindings::input_set_capability(self.ptr.as_ptr(), type_, code);
+        }
+    }
+
+    /// Sets parameter limits for an absolute axis.
+    ///
+    /// Bounds-checks `axis < ABS_CNT` (0x40) to prevent out-of-bounds writes
+    /// to the `absinfo` array in `struct input_dev`.
+    #[inline]
+    pub fn set_abs_params(
+        &mut self,
+        axis: u32,
+        min: i32,
+        max: i32,
+        fuzz: i32,
+        flat: i32,
+    ) -> Result {
+        if axis >= bindings::ABS_CNT {
+            return Err(EINVAL);
+        }
+
+        // SAFETY: `self.ptr` is valid and `axis` has been verified within bounds.
+        unsafe {
+            bindings::input_set_abs_params(self.ptr.as_ptr(), axis, min, max, fuzz, flat);
+        }
+        Ok(())
+    }
+
+    /// Registers the input device with the kernel input core.
+    ///
+    /// Consumes the `AllocatedDevice` and returns a [`RegisteredDevice`].
+    #[inline]
+    pub fn register(mut self) -> Result<RegisteredDevice> {
+        // SAFETY: `ptr` is valid and was allocated by `input_allocate_device`.
+        to_result(unsafe { bindings::input_register_device(self.ptr.as_ptr()) })?;
+
+        // SAFETY: `device_add` during `input_register_device` acquires its own reference
+        // to `parent`, so we drop our pre-registration reference to avoid a leak.
+        unsafe {
+            let parent = (*self.ptr.as_ptr()).dev.parent;
+            if !parent.is_null() {
+                bindings::put_device(parent);
+            }
+        }
+
+        let ptr = self.ptr;
+        let phys = self.phys.take();
+        core::mem::forget(self);
+
+        Ok(RegisteredDevice { ptr, _phys: phys })
+    }
+}
+
+impl Drop for AllocatedDevice {
+    #[inline]
+    fn drop(&mut self) {
+        // SAFETY: `self.ptr` was allocated by `input_allocate_device` and has not been registered.
+        unsafe {
+            let parent = (*self.ptr.as_ptr()).dev.parent;
+            if !parent.is_null() {
+                bindings::put_device(parent);
+            }
+            bindings::input_free_device(self.ptr.as_ptr());
+        }
+    }
+}
+
+// SAFETY: `AllocatedDevice` exclusively owns its `input_dev` pointer and can be transferred
+// across threads.
+unsafe impl Send for AllocatedDevice {}
+// SAFETY: `AllocatedDevice` has exclusive ownership and thread-safe methods.
+unsafe impl Sync for AllocatedDevice {}
+
+/// A registered input device capable of reporting events to userspace.
+pub struct RegisteredDevice {
+    ptr: NonNull<bindings::input_dev>,
+    _phys: Option<KBox<[u8; 64]>>,
+}
+
+impl RegisteredDevice {
+    /// Reports a binary button or key state event.
+    #[inline]
+    pub fn report_key(&self, code: u32, value: bool) {
+        // SAFETY: `self.ptr` is valid and registered with the input core.
+        unsafe {
+            bindings::input_report_key(self.ptr.as_ptr(), code, if value { 1 } else { 0 });
+        }
+    }
+
+    /// Reports an absolute axis position value.
+    #[inline]
+    pub fn report_abs(&self, code: u32, value: i32) {
+        // SAFETY: `self.ptr` is valid and registered with the input core.
+        unsafe {
+            bindings::input_report_abs(self.ptr.as_ptr(), code, value);
+        }
+    }
+
+    /// Flushes and synchronizes all reported events into a single input packet.
+    #[inline]
+    pub fn sync(&self) {
+        // SAFETY: `self.ptr` is valid and registered with the input core.
+        unsafe {
+            bindings::input_sync(self.ptr.as_ptr());
+        }
+    }
+}
+
+impl Drop for RegisteredDevice {
+    #[inline]
+    fn drop(&mut self) {
+        // SAFETY: `self.ptr` was successfully registered with `input_register_device`.
+        // Unregistering automatically unbinds and frees the device.
+        unsafe {
+            bindings::input_unregister_device(self.ptr.as_ptr());
+        }
+    }
+}
+
+// SAFETY: `RegisteredDevice` can be safely transferred across threads.
+unsafe impl Send for RegisteredDevice {}
+// SAFETY: Event reporting on `input_dev` is thread-safe (protected by internal locks in the
+// input core).
+unsafe impl Sync for RegisteredDevice {}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 1ab41129d557..ff5c978758d0 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -88,6 +88,8 @@
 #[doc(hidden)]
 pub mod impl_flags;
 pub mod init;
+#[cfg(CONFIG_INPUT = "y")]
+pub mod input;
 pub mod interop;
 pub mod interrupt;
 pub mod io;
-- 
2.56.0

[PATCH v4 2/2] rust: serio: add serio bus abstractions and port Gravis Stinger driver

[clicedvly768]

Add safe Rust abstractions for the serio (Serial I/O) bus subsystem and
port the legacy Gravis Stinger serial gamepad driver to safe Rust.

This introduces:
- `DeviceId`: a transparent wrapper around `struct serio_device_id`
  implementing `RawDeviceId` for type-safe matching tables.
- `IdTable` and `serio_device_table!` macro: guarantees a zero sentinel
  termination entry at compile time and creates modpost device aliases.
- `Device`: a serio port device instance implementing `AsBusDevice`,
  `impl_device_context_deref!`, and `as_device()` for integration
  with kernel device abstractions.
- Port lifecycle & interrupt race protection: `T::init` initializes
  driver state and registers driver data BEFORE `serio_open()` opens the
  hardware port, guaranteeing that incoming interrupts never encounter
  uninitialized state or NULL drvdata. Devices are published in `T::start`.
- `IrqReturn` mapping: properly maps `kernel::irq::IrqReturn` variants
  to C `irqreturn_t` enum values.
- `Driver` trait: safe interface for serio drivers (`init`, `start`,
  `interrupt`, `disconnect`).
- `Registration<T>`: safe RAII registration adapter that stores
  `Opaque<bindings::serio_driver>` inside `Pin<KBox<...>>` and calls
  `__serio_register_driver` with the caller's `&'static ThisModule`
  to correctly track module ownership.
- `stinger_rust`: port of the Gravis Stinger serial gamepad driver in
  safe Rust (`drivers/input/joystick/stinger_rust.rs`), containing zero
  unsafe blocks, preserving the userspace device name ("Gravis Stinger")
  for udev/EVIOCGNAME, dynamically formatting phys paths ("%s/input0"),
  and compiling as the standard `stinger.ko` module name.
- Non-regression Kconfig: adds `CONFIG_JOYSTICK_STINGER_RUST` guarded on
  `RUST && SERIO=y && INPUT=y` while retaining the original C driver
  (`stinger.c`) to maintain hardware support on non-Rust configurations
  and architectures without HAVE_RUST.
- Gated module entry `#[cfg(CONFIG_SERIO = "y")]` and helper guards
  `#if IS_REACHABLE(CONFIG_SERIO)` to avoid undefined symbols when serio
  is disabled or modular.

Signed-off-by: clicedvly768 <harepro29@gmail.com>
---
 drivers/input/joystick/Kconfig         |  14 ++
 drivers/input/joystick/Makefile        |   3 +
 drivers/input/joystick/stinger_rust.rs | 187 ++++++++++++++++
 rust/bindings/bindings_helper.h        |   1 +
 rust/helpers/helpers.c                 |   1 +
 rust/helpers/serio.c                   |  17 ++
 rust/kernel/lib.rs                     |   2 +
 rust/kernel/serio.rs                   | 298 +++++++++++++++++++++++++
 8 files changed, 523 insertions(+)
 create mode 100644 drivers/input/joystick/stinger_rust.rs
 create mode 100644 rust/helpers/serio.c
 create mode 100644 rust/kernel/serio.rs

diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
index 7755e5b454d2..89cc1dd9d865 100644
--- a/drivers/input/joystick/Kconfig
+++ b/drivers/input/joystick/Kconfig
@@ -197,6 +197,20 @@ config JOYSTICK_STINGER
 	  To compile this driver as a module, choose M here: the
 	  module will be called stinger.
 
+config JOYSTICK_STINGER_RUST
+	bool "Safe Rust implementation of Gravis Stinger gamepad driver"
+	depends on JOYSTICK_STINGER
+	depends on RUST && SERIO = y && INPUT = y
+	default y
+	help
+	  Say Y here to use the safe Rust rewrite of the Gravis Stinger
+	  gamepad driver instead of the legacy C implementation.
+
+	  The Rust driver provides memory safety guarantees while preserving
+	  full hardware protocol compatibility.
+
+	  If unsure, say Y.
+
 config JOYSTICK_TWIDJOY
 	tristate "Twiddler as a joystick"
 	select SERIO
diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile
index 9976f596a920..2ba3391af7c9 100644
--- a/drivers/input/joystick/Makefile
+++ b/drivers/input/joystick/Makefile
@@ -33,6 +33,9 @@ obj-$(CONFIG_JOYSTICK_SENSEHAT)	+= sensehat-joystick.o
 obj-$(CONFIG_JOYSTICK_SIDEWINDER)	+= sidewinder.o
 obj-$(CONFIG_JOYSTICK_SPACEBALL)	+= spaceball.o
 obj-$(CONFIG_JOYSTICK_SPACEORB)		+= spaceorb.o
+ifdef CONFIG_JOYSTICK_STINGER_RUST
+stinger-objs				:= stinger_rust.o
+endif
 obj-$(CONFIG_JOYSTICK_STINGER)		+= stinger.o
 obj-$(CONFIG_JOYSTICK_TMDC)		+= tmdc.o
 obj-$(CONFIG_JOYSTICK_TURBOGRAFX)	+= turbografx.o
diff --git a/drivers/input/joystick/stinger_rust.rs b/drivers/input/joystick/stinger_rust.rs
new file mode 100644
index 000000000000..ca8d677ddbdb
--- /dev/null
+++ b/drivers/input/joystick/stinger_rust.rs
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+//! Gravis Stinger gamepad driver written in safe Rust.
+//!
+//! Rust port of legacy C driver `drivers/input/joystick/stinger.c`.
+//!
+//! Authors:
+//! - Original C driver: Vojtech Pavlik <vojtech@ucw.cz>, Mark Fletcher
+//! - Rust port: Rust for Linux Contributors
+
+use kernel::{
+    bindings, //
+    device,   //
+    input::{
+        bus,              //
+        event_type,       //
+        AllocatedDevice,  //
+        RegisteredDevice, //
+    }, //
+    prelude::*, //
+    serio::{
+        self,      //
+        IrqReturn, //
+    }, //
+    types::ForeignOwnable, //
+};
+
+const DRIVER_NAME: &CStr = c"stinger";
+const DRIVER_DESC: &CStr = c"Gravis Stinger";
+const DRIVER_SERIO_DESC: &CStr = c"Gravis Stinger gamepad driver";
+
+const STINGER_MAX_LENGTH: usize = 8;
+
+kernel::serio_device_table!(
+    STINGER_IDS,
+    [serio::DeviceId::new(
+        bindings::SERIO_RS232 as u8,
+        bindings::SERIO_ANY as u8,
+        bindings::SERIO_ANY as u8,
+        bindings::SERIO_STINGER as u8,
+    )]
+);
+
+/// Per-device state for an attached Gravis Stinger gamepad.
+struct Stinger {
+    input: RegisteredDevice,
+    idx: usize,
+    data: [u8; STINGER_MAX_LENGTH],
+}
+
+impl Stinger {
+    /// Decodes incoming 4-byte packets from the Gravis Stinger and reports input events.
+    fn process_packet(&self) {
+        if self.idx == 0 {
+            return;
+        }
+
+        let d0 = i32::from(self.data[0]);
+        let d1 = i32::from(self.data[1]);
+        let d2 = i32::from(self.data[2]);
+        let d3 = i32::from(self.data[3]);
+
+        // Report button states (active high bits in packet)
+        self.input
+            .report_key(bindings::BTN_A, ((d0 & 0x20) >> 5) != 0);
+        self.input
+            .report_key(bindings::BTN_B, ((d0 & 0x10) >> 4) != 0);
+        self.input
+            .report_key(bindings::BTN_C, ((d0 & 0x08) >> 3) != 0);
+        self.input
+            .report_key(bindings::BTN_X, ((d0 & 0x04) >> 2) != 0);
+        self.input
+            .report_key(bindings::BTN_Y, ((d3 & 0x20) >> 5) != 0);
+        self.input
+            .report_key(bindings::BTN_Z, ((d3 & 0x10) >> 4) != 0);
+        self.input
+            .report_key(bindings::BTN_TL, ((d3 & 0x08) >> 3) != 0);
+        self.input
+            .report_key(bindings::BTN_TR, ((d3 & 0x04) >> 2) != 0);
+        self.input
+            .report_key(bindings::BTN_SELECT, ((d3 & 0x02) >> 1) != 0);
+        self.input.report_key(bindings::BTN_START, (d3 & 0x01) != 0);
+
+        // Report 2-axis position: coordinates in range -64..64
+        self.input
+            .report_abs(bindings::ABS_X, (d1 & 0x3f) - ((d0 & 0x01) << 6));
+        self.input
+            .report_abs(bindings::ABS_Y, ((d0 & 0x02) << 5) - (d2 & 0x3f));
+
+        self.input.sync();
+    }
+}
+
+/// Serio driver implementation for Gravis Stinger gamepad.
+struct StingerDriver;
+
+impl serio::Driver for StingerDriver {
+    type Data = KBox<Stinger>;
+
+    const ID_TABLE: serio::IdTable = &STINGER_IDS;
+
+    fn connect(dev: &serio::Device<device::Bound>) -> Result<Self::Data> {
+        let mut input_alloc = AllocatedDevice::new()?;
+
+        input_alloc.set_name(DRIVER_DESC);
+        input_alloc.set_id(bus::RS232, bindings::SERIO_STINGER as u16, 0x0001, 0x0100);
+        input_alloc.set_parent(dev.as_device());
+        input_alloc.set_phys_from_parent(dev.phys())?;
+
+        // Configure supported buttons
+        for btn in [
+            bindings::BTN_A,
+            bindings::BTN_B,
+            bindings::BTN_C,
+            bindings::BTN_X,
+            bindings::BTN_Y,
+            bindings::BTN_Z,
+            bindings::BTN_TL,
+            bindings::BTN_TR,
+            bindings::BTN_START,
+            bindings::BTN_SELECT,
+        ] {
+            input_alloc.set_capability(event_type::KEY, btn);
+        }
+
+        // Configure 2-axis analog input
+        input_alloc.set_abs_params(bindings::ABS_X, -64, 64, 0, 4)?;
+        input_alloc.set_abs_params(bindings::ABS_Y, -64, 64, 0, 4)?;
+
+        let registered = input_alloc.register()?;
+
+        let stinger = KBox::new(
+            Stinger {
+                input: registered,
+                idx: 0,
+                data: [0; STINGER_MAX_LENGTH],
+            },
+            GFP_KERNEL,
+        )?;
+
+        Ok(stinger)
+    }
+
+    fn interrupt(
+        stinger: &mut <Self::Data as ForeignOwnable>::BorrowedMut<'_>,
+        data: u8,
+        _flags: u32,
+    ) -> IrqReturn {
+        if stinger.idx < STINGER_MAX_LENGTH {
+            stinger.data[stinger.idx] = data;
+            stinger.idx += 1;
+        }
+
+        if stinger.idx == 4 {
+            stinger.process_packet();
+            stinger.idx = 0;
+        }
+
+        IrqReturn::Handled
+    }
+
+    #[inline]
+    fn disconnect(_data: Self::Data) {
+        // Automatically drops `stinger`, unregistering and freeing the input device.
+    }
+}
+
+module! {
+    type: StingerModule,
+    name: "stinger",
+    authors: ["Rust for Linux Contributors"],
+    description: "Gravis Stinger gamepad driver in safe Rust",
+    license: "GPL",
+}
+
+struct StingerModule {
+    _reg: serio::Registration<StingerDriver>,
+}
+
+impl kernel::Module for StingerModule {
+    fn init(module: &'static ThisModule) -> Result<Self> {
+        let reg =
+            serio::Registration::<StingerDriver>::new(DRIVER_NAME, DRIVER_SERIO_DESC, module)?;
+        pr_info!("Gravis Stinger safe Rust driver initialized\n");
+        Ok(Self { _reg: reg })
+    }
+}
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 4b09d3980e10..0e44af5d770c 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -89,6 +89,7 @@
 #include <linux/sched.h>
 #include <linux/security.h>
 #include <linux/serdev.h>
+#include <linux/serio.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 77cec85ad153..61cf3f77e85a 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -96,6 +96,7 @@
 #include "scatterlist.c"
 #include "security.c"
 #include "serdev.c"
+#include "serio.c"
 #include "signal.c"
 #include "slab.c"
 #include "spinlock.c"
diff --git a/rust/helpers/serio.c b/rust/helpers/serio.c
new file mode 100644
index 000000000000..849d0d48ac62
--- /dev/null
+++ b/rust/helpers/serio.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/serio.h>
+
+#if IS_REACHABLE(CONFIG_SERIO)
+
+__rust_helper void *rust_helper_serio_get_drvdata(struct serio *serio)
+{
+	return serio_get_drvdata(serio);
+}
+
+__rust_helper void rust_helper_serio_set_drvdata(struct serio *serio, void *data)
+{
+	serio_set_drvdata(serio, data);
+}
+
+#endif /* IS_REACHABLE(CONFIG_SERIO) */
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index ff5c978758d0..711b7ef06b57 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -134,6 +134,8 @@
 pub mod seq_file;
 #[cfg(CONFIG_RUST_SERIAL_DEV_BUS_ABSTRACTIONS)]
 pub mod serdev;
+#[cfg(CONFIG_SERIO = "y")]
+pub mod serio;
 pub mod sizes;
 #[cfg(CONFIG_SOC_BUS)]
 pub mod soc;
diff --git a/rust/kernel/serio.rs b/rust/kernel/serio.rs
new file mode 100644
index 000000000000..1878055fb644
--- /dev/null
+++ b/rust/kernel/serio.rs
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Serio (Serial I/O) bus abstractions for safe Rust drivers.
+//!
+//! Provides a safe Rust interface for serio devices and drivers in the Linux kernel,
+//! supporting input devices such as serial gamepads (e.g. Gravis Stinger), mice, and keyboards.
+
+use crate::{
+    bindings, //
+    device,   //
+    device_id::{
+        IdTable as GenericIdTable, //
+        RawDeviceId,               //
+    }, //
+    error::{
+        to_result, //
+        Result,    //
+    }, //
+    ffi::{
+        c_int,   //
+        c_uchar, //
+        c_uint,  //
+    }, //
+    prelude::*, //
+    types::{
+        ForeignOwnable, //
+        Opaque,         //
+    }, //
+    ThisModule, //
+};
+use core::{
+    marker::PhantomData, //
+    pin::Pin,            //
+};
+
+pub use crate::irq::IrqReturn;
+
+/// Identifies supported serio hardware devices for auto-probing and matching.
+#[repr(transparent)]
+#[derive(Copy, Clone)]
+pub struct DeviceId(bindings::serio_device_id);
+
+impl DeviceId {
+    /// Creates a new serio device identifier.
+    #[inline]
+    pub const fn new(type_: u8, extra: u8, id: u8, proto: u8) -> Self {
+        Self(bindings::serio_device_id {
+            type_,
+            extra,
+            id,
+            proto,
+        })
+    }
+}
+
+// SAFETY: `DeviceId` is a `#[repr(transparent)]` wrapper around `bindings::serio_device_id`.
+unsafe impl RawDeviceId for DeviceId {
+    type RawType = bindings::serio_device_id;
+}
+
+/// Type alias for serio device ID tables.
+pub type IdTable = &'static dyn GenericIdTable<DeviceId, ()>;
+
+/// Creates a serio device table with a zero sentinel for module autoloading and matching.
+#[macro_export]
+macro_rules! serio_device_table {
+    ($table_name:ident, [$($id:expr),* $(,)?]) => {
+        $crate::module_device_table!(
+            "serio",
+            $crate::serio::DeviceId,
+            $table_name,
+            @none,
+            [$($id),*]
+        );
+    };
+}
+
+/// A serio port device instance passed to driver callbacks.
+#[repr(transparent)]
+pub struct Device<Ctx: device::DeviceContext = device::Normal>(
+    Opaque<bindings::serio>,
+    PhantomData<Ctx>,
+);
+
+impl<Ctx: device::DeviceContext> Device<Ctx> {
+    /// Returns the raw pointer to the underlying `struct serio`.
+    #[inline]
+    pub fn as_raw(&self) -> *mut bindings::serio {
+        self.0.get()
+    }
+
+    /// Reads the physical device path into a buffer.
+    #[inline]
+    pub fn phys(&self) -> &[u8; 32] {
+        // SAFETY: `self.as_raw()` points to a valid `struct serio`.
+        unsafe { &(*self.as_raw()).phys }
+    }
+
+    /// Returns a reference to the base [`device::Device`].
+    #[inline]
+    pub fn as_device(&self) -> &device::Device {
+        // SAFETY: `self.as_raw()` points to a valid `struct serio`.
+        unsafe {
+            let dev = core::ptr::addr_of_mut!((*self.as_raw()).dev);
+            device::Device::from_raw(dev)
+        }
+    }
+}
+
+// SAFETY: `serio::Device` is a transparent wrapper of `struct serio`.
+// The offset is guaranteed to point to a valid device field inside `serio::Device`.
+unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for Device<Ctx> {
+    const OFFSET: usize = core::mem::offset_of!(bindings::serio, dev);
+}
+
+kernel::impl_device_context_deref!(unsafe { Device });
+
+impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for Device<Ctx> {
+    #[inline]
+    fn as_ref(&self) -> &device::Device<Ctx> {
+        // SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid
+        // `struct serio`.
+        let dev = unsafe { core::ptr::addr_of_mut!((*self.as_raw()).dev) };
+
+        // SAFETY: `dev` points to a valid `struct device`.
+        unsafe { device::Device::from_raw(dev) }
+    }
+}
+
+/// Trait implemented by serio device drivers.
+pub trait Driver: Send + Sync + Sized {
+    /// Context data stored per connected device instance.
+    type Data: ForeignOwnable + Send + Sync;
+
+    /// Device ID match table.
+    const ID_TABLE: IdTable;
+
+    /// Initializes driver data and registers child devices when a matching port is detected.
+    fn connect(dev: &Device<device::Bound>) -> Result<Self::Data>;
+
+    /// Called in interrupt context when a new byte arrives from the serio port.
+    fn interrupt(
+        data: &mut <Self::Data as ForeignOwnable>::BorrowedMut<'_>,
+        byte: u8,
+        flags: u32,
+    ) -> IrqReturn;
+
+    /// Called when the device is disconnected.
+    #[inline]
+    fn disconnect(_data: Self::Data) {}
+}
+
+/// Driver adapter that bridges the safe Rust [`Driver`] trait to the C serio bus subsystem.
+pub struct Registration<T: Driver> {
+    drv: Pin<KBox<Opaque<bindings::serio_driver>>>,
+    _p: PhantomData<T>,
+}
+
+impl<T: Driver> Registration<T> {
+    /// Registers a serio driver with the kernel.
+    pub fn new(
+        name: &'static CStr,
+        description: &'static CStr,
+        module: &'static ThisModule,
+    ) -> Result<Self> {
+        let drv = bindings::serio_driver {
+            description: description.as_char_ptr(),
+            id_table: T::ID_TABLE.as_ptr(),
+            manual_bind: false,
+            write_wakeup: None,
+            interrupt: Some(Self::interrupt_callback),
+            connect: Some(Self::connect_callback),
+            reconnect: None,
+            fast_reconnect: None,
+            disconnect: Some(Self::disconnect_callback),
+            cleanup: None,
+            driver: bindings::device_driver {
+                name: name.as_char_ptr(),
+                ..Default::default()
+            },
+        };
+
+        let drv_box = KBox::into_pin(KBox::new(Opaque::new(drv), GFP_KERNEL)?);
+
+        // SAFETY: `drv_box` is pinned on the kernel heap at a permanent address.
+        // `module` and `name` are valid static references.
+        let ret = unsafe {
+            bindings::__serio_register_driver(drv_box.get(), module.as_ptr(), name.as_char_ptr())
+        };
+        to_result(ret)?;
+
+        Ok(Self {
+            drv: drv_box,
+            _p: PhantomData,
+        })
+    }
+
+    /// # Safety
+    ///
+    /// Must only be invoked by the serio subsystem when a matching port is probed.
+    /// `serio` and `drv` must be valid non-null pointers provided by the kernel.
+    unsafe extern "C" fn connect_callback(
+        serio: *mut bindings::serio,
+        drv: *mut bindings::serio_driver,
+    ) -> c_int {
+        if serio.is_null() {
+            return crate::error::code::EINVAL.to_errno();
+        }
+
+        // SAFETY: `serio` is valid. `Device<Bound>` is repr(transparent).
+        let dev = unsafe { &*(serio.cast::<Device<device::Bound>>()) };
+
+        // 1. Initialize driver data and register input devices before the port is opened.
+        let data = match T::connect(dev) {
+            Ok(d) => d,
+            Err(e) => return e.to_errno(),
+        };
+
+        let raw_data = data.into_foreign();
+
+        // 2. Set drvdata BEFORE opening port so interrupts never encounter NULL.
+        // SAFETY: `serio` is valid; store driver data pointer.
+        unsafe {
+            bindings::serio_set_drvdata(serio, raw_data.cast());
+        }
+
+        // 3. Open serio port.
+        // SAFETY: `serio` and `drv` are valid non-null pointers provided by the kernel.
+        let ret = unsafe { bindings::serio_open(serio, drv) };
+        if ret != 0 {
+            // SAFETY: Clean up drvdata if open failed.
+            unsafe {
+                bindings::serio_set_drvdata(serio, core::ptr::null_mut());
+                let data = <T::Data as ForeignOwnable>::from_foreign(raw_data);
+                T::disconnect(data);
+            }
+            return ret;
+        }
+
+        0
+    }
+
+    /// # Safety
+    ///
+    /// Must only be invoked by the serio subsystem during an interrupt on a connected port.
+    /// `serio` must be a valid pointer.
+    unsafe extern "C" fn interrupt_callback(
+        serio: *mut bindings::serio,
+        data: c_uchar,
+        flags: c_uint,
+    ) -> bindings::irqreturn_t {
+        // SAFETY: `serio` is valid.
+        let raw = unsafe { bindings::serio_get_drvdata(serio) };
+        if raw.is_null() {
+            return bindings::irqreturn_t(IrqReturn::None as c_uint);
+        }
+
+        // SAFETY: `raw` was created via `into_foreign()` in `connect_callback`.
+        let mut borrowed = unsafe { <T::Data as ForeignOwnable>::borrow_mut(raw) };
+        let ret = T::interrupt(&mut borrowed, data, flags);
+        bindings::irqreturn_t(ret as c_uint)
+    }
+
+    /// # Safety
+    ///
+    /// Must only be invoked by the serio subsystem when disconnecting a port.
+    /// `serio` must be a valid pointer.
+    unsafe extern "C" fn disconnect_callback(serio: *mut bindings::serio) {
+        // SAFETY: `serio` is valid.
+        let raw = unsafe { bindings::serio_get_drvdata(serio) };
+        if raw.is_null() {
+            return;
+        }
+
+        // SAFETY: Close port, clear drvdata, and pass owned data back to disconnect.
+        unsafe {
+            bindings::serio_close(serio);
+            bindings::serio_set_drvdata(serio, core::ptr::null_mut());
+            let data = <T::Data as ForeignOwnable>::from_foreign(raw);
+            T::disconnect(data);
+        }
+    }
+}
+
+impl<T: Driver> Drop for Registration<T> {
+    #[inline]
+    fn drop(&mut self) {
+        // SAFETY: Unregister driver with kernel. `self.drv` is valid and registered.
+        unsafe {
+            bindings::serio_unregister_driver(self.drv.get());
+        }
+    }
+}
+
+// SAFETY: `Registration` can be safely sent to another thread.
+unsafe impl<T: Driver> Send for Registration<T> {}
+// SAFETY: `Registration` can be safely shared across threads.
+unsafe impl<T: Driver> Sync for Registration<T> {}
-- 
2.56.0

Re: [PATCH v4 2/2] rust: serio: add serio bus abstractions and port Gravis Stinger driver

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 3 potential
issues to consider:
- [High] rust: serio: invalid irqreturn_t constructor call in
  interrupt_callback()
- [Medium] rust: serio: premature input registration before serio_open()
  in connect()
- [Low] rust: serio: redundant as_device() and public as_raw() on
  serio::Device
--

commit 98f91fdb41f94854e741d0d25d20d83c3e00ed06
Author: clicedvly768 <harepro29@gmail.com>

rust: serio: add serio bus abstractions and port Gravis Stinger driver

This commit adds Rust abstractions for the serio bus subsystem and ports the
Gravis Stinger serial gamepad driver to Rust.

> diff --git a/rust/kernel/serio.rs b/rust/kernel/serio.rs
> new file mode 100644
> index 0000000000000..1878055fb6449
> --- /dev/null
> +++ b/rust/kernel/serio.rs
[ ... ]
> +impl<Ctx: device::DeviceContext> Device<Ctx> {
> +    /// Returns the raw pointer to the underlying `struct serio`.
> +    #[inline]
> +    pub fn as_raw(&self) -> *mut bindings::serio {
> +        self.0.get()
> +    }
> +
> +    /// Reads the physical device path into a buffer.
> +    #[inline]
> +    pub fn phys(&self) -> &[u8; 32] {
> +        // SAFETY: `self.as_raw()` points to a valid `struct serio`.
> +        unsafe { &(*self.as_raw()).phys }
> +    }
> +
> +    /// Returns a reference to the base [`device::Device`].
> +    #[inline]
> +    pub fn as_device(&self) -> &device::Device {
> +        // SAFETY: `self.as_raw()` points to a valid `struct serio`.
> +        unsafe {
> +            let dev = core::ptr::addr_of_mut!((*self.as_raw()).dev);
> +            device::Device::from_raw(dev)
> +        }
> +    }
> +}
> +
> +// SAFETY: `serio::Device` is a transparent wrapper of `struct serio`.
> +// The offset is guaranteed to point to a valid device field inside `serio::Device`.
> +unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for Device<Ctx> {
> +    const OFFSET: usize = core::mem::offset_of!(bindings::serio, dev);
> +}
> +
> +kernel::impl_device_context_deref!(unsafe { Device });
> +
> +impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for Device<Ctx> {
> +    #[inline]
> +    fn as_ref(&self) -> &device::Device<Ctx> {
> +        // SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid
> +        // `struct serio`.
> +        let dev = unsafe { core::ptr::addr_of_mut!((*self.as_raw()).dev) };
> +
> +        // SAFETY: `dev` points to a valid `struct device`.
> +        unsafe { device::Device::from_raw(dev) }
> +    }
> +}

[Severity: Low]
This isn't a bug, but Device::as_device() duplicates the
AsRef<device::Device<Ctx>> implementation right below it while erasing the
DeviceContext parameter Ctx.  Other bus device abstractions in rust/kernel/
expose the base device through as_ref() (which StingerDriver::connect() can
call instead of as_device()) and keep as_raw() private or pub(crate) rather
than exposing the raw pointer outside the kernel crate.

> +
> +/// Trait implemented by serio device drivers.
> +pub trait Driver: Send + Sync + Sized {
> +    /// Context data stored per connected device instance.
> +    type Data: ForeignOwnable + Send + Sync;
> +
> +    /// Device ID match table.
> +    const ID_TABLE: IdTable;
> +
> +    /// Initializes driver data and registers child devices when a matching port is detected.
> +    fn connect(dev: &Device<device::Bound>) -> Result<Self::Data>;
[ ... ]
> +    unsafe extern "C" fn connect_callback(
> +        serio: *mut bindings::serio,
> +        drv: *mut bindings::serio_driver,
> +    ) -> c_int {
> +        if serio.is_null() {
> +            return crate::error::code::EINVAL.to_errno();
> +        }
> +
> +        // SAFETY: `serio` is valid. `Device<Bound>` is repr(transparent).
> +        let dev = unsafe { &*(serio.cast::<Device<device::Bound>>()) };
> +
> +        // 1. Initialize driver data and register input devices before the port is opened.
> +        let data = match T::connect(dev) {
> +            Ok(d) => d,
> +            Err(e) => return e.to_errno(),
> +        };
> +
> +        let raw_data = data.into_foreign();
> +
> +        // 2. Set drvdata BEFORE opening port so interrupts never encounter NULL.
> +        // SAFETY: `serio` is valid; store driver data pointer.
> +        unsafe {
> +            bindings::serio_set_drvdata(serio, raw_data.cast());
> +        }
> +
> +        // 3. Open serio port.
> +        // SAFETY: `serio` and `drv` are valid non-null pointers provided by the kernel.
> +        let ret = unsafe { bindings::serio_open(serio, drv) };
> +        if ret != 0 {
> +            // SAFETY: Clean up drvdata if open failed.
> +            unsafe {
> +                bindings::serio_set_drvdata(serio, core::ptr::null_mut());
> +                let data = <T::Data as ForeignOwnable>::from_foreign(raw_data);
> +                T::disconnect(data);
> +            }
> +            return ret;
> +        }
> +
> +        0
> +    }

[Severity: Medium]
Does calling T::connect() before bindings::serio_open() publish the input
device to userspace before the serio port is opened?

In StingerDriver::connect(), input_alloc.register() registers the input
device and emits a KOBJ_ADD uevent before KBox::new() allocates the Stinger
state and before connect_callback() calls serio_open():

drivers/input/joystick/stinger_rust.rs:StingerDriver::connect() {
    ...
        let registered = input_alloc.register()?;

        let stinger = KBox::new(
            Stinger {
                input: registered,
                idx: 0,
                data: [0; STINGER_MAX_LENGTH],
            },
            GFP_KERNEL,
        )?;
    ...
}

In the C stinger driver, input_register_device() is only called after
serio_open() succeeds.  With the single connect() callback here, userspace
can open the input device before the underlying serio port is open, and if
KBox::new() or serio_open() fails, the input device is published and
immediately unregistered (emitting spurious KOBJ_ADD and KOBJ_REMOVE
uevents) and T::disconnect() is invoked on a connection that never
succeeded.

Also, the commit message states that Driver provides separate init and start
callbacks so devices are published in T::start after serio_open(), which
does not match the Driver trait in the patch.

> +
> +    /// # Safety
> +    ///
> +    /// Must only be invoked by the serio subsystem during an interrupt on a connected port.
> +    /// `serio` must be a valid pointer.
> +    unsafe extern "C" fn interrupt_callback(
> +        serio: *mut bindings::serio,
> +        data: c_uchar,
> +        flags: c_uint,
> +    ) -> bindings::irqreturn_t {
> +        // SAFETY: `serio` is valid.
> +        let raw = unsafe { bindings::serio_get_drvdata(serio) };
> +        if raw.is_null() {
> +            return bindings::irqreturn_t(IrqReturn::None as c_uint);
> +        }
> +
> +        // SAFETY: `raw` was created via `into_foreign()` in `connect_callback`.
> +        let mut borrowed = unsafe { <T::Data as ForeignOwnable>::borrow_mut(raw) };
> +        let ret = T::interrupt(&mut borrowed, data, flags);
> +        bindings::irqreturn_t(ret as c_uint)
> +    }

[Severity: High]
Does bindings::irqreturn_t(...) fail to compile when CONFIG_SERIO=y and
CONFIG_RUST=y are enabled?

bindgen generates bindings::irqreturn_t as a type alias for c_uint rather
than a tuple struct, so calling bindings::irqreturn_t(...) as a constructor
fails with rustc error E0423.  Cast the return value with
IrqReturn::None as bindings::irqreturn_t and ret as bindings::irqreturn_t
instead.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261106214322.421869-1-harepro29@gmail.com?part=2