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Fri, 06 Nov 2026 23:00:23 -0800 (PST) Received: from DESKTOP-KHFMJSR ([194.9.62.193]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4b7a0e1f298sm31506415e9.4.2026.11.06.23.00.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Nov 2026 23:00:22 -0800 (PST) From: Vecheslav Filatov To: ojeda@kernel.org, dmitry.torokhov@gmail.com Cc: rust-for-linux@vger.kernel.org, linux-input@vger.kernel.org, Vecheslav Filatov Subject: [PATCH v8 2/2] rust: serio: add serio bus abstractions and port Gravis Stinger driver Date: Sat, 7 Nov 2026 12:00:10 +0500 Message-ID: <20261107070010.500128-3-harepro29@gmail.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261107070010.500128-1-harepro29@gmail.com> References: <20261107070010.500128-1-harepro29@gmail.com> X-Mailing-List: linux-input@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 AsRef. - Port lifecycle & interrupt race protection: T::init initializes driver state and allocates input devices, storing drvdata BEFORE serio_open() opens the hardware port. T::start publishes child devices only after serio_open() succeeds, and T::attach safely binds them under serio_pause_rx with bounded borrow_mut lifetime. - IrqReturn mapping: directly returns bindings::irqreturn_IRQ_* constants without constructor calls or UB. - Driver trait: safe interface for serio drivers (init, start, attach, interrupt, disconnect). - Registration: safe RAII registration adapter that stores Opaque inside Pin> 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 with crate-name stinger for correct builtin modalias. - 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: Vecheslav Filatov --- drivers/input/joystick/Kconfig | 14 ++ drivers/input/joystick/Makefile | 4 + drivers/input/joystick/stinger_rust.rs | 191 ++++++++++++++ rust/bindings/bindings_helper.h | 1 + rust/helpers/helpers.c | 1 + rust/helpers/serio.c | 27 ++ rust/kernel/lib.rs | 2 + rust/kernel/serio.rs | 336 +++++++++++++++++++++++++ 8 files changed, 576 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..f5101ced0b6c 100644 --- a/drivers/input/joystick/Makefile +++ b/drivers/input/joystick/Makefile @@ -33,6 +33,10 @@ 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 +RUSTFLAGS_stinger_rust.o := --crate-name stinger +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..af78524fadcf --- /dev/null +++ b/drivers/input/joystick/stinger_rust.rs @@ -0,0 +1,191 @@ +// 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 , 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: Option, + 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) { + let Some(input) = self.input.as_ref() else { + return; + }; + + 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) + input.report_key(bindings::BTN_A, ((d0 & 0x20) >> 5) != 0); + input.report_key(bindings::BTN_B, ((d0 & 0x10) >> 4) != 0); + input.report_key(bindings::BTN_C, ((d0 & 0x08) >> 3) != 0); + input.report_key(bindings::BTN_X, ((d0 & 0x04) >> 2) != 0); + input.report_key(bindings::BTN_Y, ((d3 & 0x20) >> 5) != 0); + input.report_key(bindings::BTN_Z, ((d3 & 0x10) >> 4) != 0); + input.report_key(bindings::BTN_TL, ((d3 & 0x08) >> 3) != 0); + input.report_key(bindings::BTN_TR, ((d3 & 0x04) >> 2) != 0); + input.report_key(bindings::BTN_SELECT, ((d3 & 0x02) >> 1) != 0); + input.report_key(bindings::BTN_START, (d3 & 0x01) != 0); + + // Report 2-axis position: coordinates in range -64..64 + input.report_abs(bindings::ABS_X, (d1 & 0x3f) - ((d0 & 0x01) << 6)); + input.report_abs(bindings::ABS_Y, ((d0 & 0x02) << 5) - (d2 & 0x3f)); + + input.sync(); + } +} + +/// Serio driver implementation for Gravis Stinger gamepad. +struct StingerDriver; + +impl serio::Driver for StingerDriver { + type Data = KBox; + type Pending = AllocatedDevice; + type Published = RegisteredDevice; + + const ID_TABLE: serio::IdTable = &STINGER_IDS; + + fn init(dev: &serio::Device) -> Result<(Self::Data, Self::Pending)> { + 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_ref()); + 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 stinger = KBox::new( + Stinger { + input: None, + idx: 0, + data: [0; STINGER_MAX_LENGTH], + }, + GFP_KERNEL, + )?; + + Ok((stinger, input_alloc)) + } + + fn start(pending: Self::Pending) -> Result { + pending.register() + } + + fn attach( + stinger: &mut ::BorrowedMut<'_>, + published: Self::Published, + ) { + stinger.input = Some(published); + } + + fn interrupt( + stinger: &mut ::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, +} + +impl kernel::Module for StingerModule { + fn init(module: &'static ThisModule) -> Result { + let reg = + serio::Registration::::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 #include #include +#include #include #include #include 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..f88b6c2a900b --- /dev/null +++ b/rust/helpers/serio.c @@ -0,0 +1,27 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +#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); +} + +__rust_helper void rust_helper_serio_pause_rx(struct serio *serio) +{ + serio_pause_rx(serio); +} + +__rust_helper void rust_helper_serio_continue_rx(struct serio *serio) +{ + serio_continue_rx(serio); +} + +#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..4e16917ddd70 --- /dev/null +++ b/rust/kernel/serio.rs @@ -0,0 +1,336 @@ +// 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; + +#[allow(non_upper_case_globals)] +const irqreturn_IRQ_NONE: bindings::irqreturn_t = bindings::irqreturn::IRQ_NONE; +#[allow(non_upper_case_globals)] +const irqreturn_IRQ_HANDLED: bindings::irqreturn_t = bindings::irqreturn::IRQ_HANDLED; + +/// 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; + +/// 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( + Opaque, + PhantomData, +); + +impl Device { + /// Returns the raw pointer to the underlying `struct serio`. + #[inline] + pub(crate) 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 } + } +} + +// 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 device::AsBusDevice for Device { + const OFFSET: usize = core::mem::offset_of!(bindings::serio, dev); +} + +kernel::impl_device_context_deref!(unsafe { Device }); + +impl AsRef> for Device { + #[inline] + fn as_ref(&self) -> &device::Device { + // 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; + + /// Pending resources allocated during probe to be published after the port opens. + type Pending; + + /// Published device handle created after the port opens. + type Published; + + /// Device ID match table. + const ID_TABLE: IdTable; + + /// Initializes driver data before the port is opened. + fn init(dev: &Device) -> Result<(Self::Data, Self::Pending)>; + + /// Registers/publishes child devices in process context after `serio_open` succeeds. + fn start(pending: Self::Pending) -> Result; + + /// Attaches the published child device under `serio_pause_rx` to eliminate races. + fn attach( + data: &mut ::BorrowedMut<'_>, + published: Self::Published, + ); + + /// Called in interrupt context when a new byte arrives from the serio port. + fn interrupt( + data: &mut ::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 { + drv: Pin>>, + _p: PhantomData, +} + +impl Registration { + /// Registers a serio driver with the kernel. + pub fn new( + name: &'static CStr, + description: &'static CStr, + module: &'static ThisModule, + ) -> Result { + 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` is repr(transparent). + let dev = unsafe { &*(serio.cast::>()) }; + + // 1. Initialize driver data before port is opened. + let (data, pending) = match T::init(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 = ::from_foreign(raw_data); + T::disconnect(data); + } + return ret; + } + + // 4. Publish child devices in process context now that port is successfully opened. + let published = match T::start(pending) { + Ok(p) => p, + Err(e) => { + // SAFETY: Close port and clean up if device publication failed. + unsafe { + bindings::serio_close(serio); + bindings::serio_set_drvdata(serio, core::ptr::null_mut()); + let data = ::from_foreign(raw_data); + T::disconnect(data); + } + return e.to_errno(); + } + }; + + // 5. Attach published resources under `serio_pause_rx` to eliminate races with interrupts. + // SAFETY: `serio_pause_rx` holds `serio->lock`, preventing concurrent interrupt execution. + unsafe { + bindings::serio_pause_rx(serio); + { + let mut borrowed = ::borrow_mut(raw_data); + T::attach(&mut borrowed, published); + } + bindings::serio_continue_rx(serio); + } + + 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 irqreturn_IRQ_NONE; + } + + // SAFETY: `raw` was created via `into_foreign()` in `connect_callback`. + let mut borrowed = unsafe { ::borrow_mut(raw) }; + match T::interrupt(&mut borrowed, data, flags) { + IrqReturn::None => irqreturn_IRQ_NONE, + IrqReturn::Handled => irqreturn_IRQ_HANDLED, + } + } + + /// # 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 = ::from_foreign(raw); + T::disconnect(data); + } + } +} + +impl Drop for Registration { + #[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 Send for Registration {} +// SAFETY: `Registration` can be safely shared across threads. +unsafe impl Sync for Registration {} -- 2.56.0