* [PATCH v4 1/2] rust: core abstractions for HID drivers
2025-09-17 22:53 [PATCH v4 0/2] Initial work for Rust abstraction for HID device driver development Rahul Rameshbabu
@ 2025-09-17 22:53 ` Rahul Rameshbabu
2025-09-17 22:54 ` [PATCH v4 2/2] rust: hid: Glorious PC Gaming Race Model O and O- mice reference driver Rahul Rameshbabu
1 sibling, 0 replies; 3+ messages in thread
From: Rahul Rameshbabu @ 2025-09-17 22:53 UTC (permalink / raw)
To: linux-input, linux-kernel, rust-for-linux
Cc: a.hindborg, alex.gaynor, aliceryhl, benjamin.tissoires,
benno.lossin, bjorn3_gh, boqun.feng, dakr, db48x, gary, jikos,
ojeda, peter.hutterer, tmgross, Rahul Rameshbabu
These abstractions enable the development of HID drivers in Rust by binding
with the HID core C API. They provide Rust types that map to the
equivalents in C. In this initial draft, only hid_device and hid_device_id
are provided direct Rust type equivalents. hid_driver is specially wrapped
with a custom Driver type. The module_hid_driver! macro provides analogous
functionality to its C equivalent. Only the .report_fixup callback is
binded to Rust so far.
Future work for these abstractions would include more bindings for common
HID-related types, such as hid_field, hid_report_enum, and hid_report as
well as more bus callbacks. Providing Rust equivalents to useful core HID
functions will also be necessary for HID driver development in Rust.
Signed-off-by: Rahul Rameshbabu <sergeantsagara@protonmail.com>
---
Notes:
Changelog:
v3->v4:
* Removed specifying tree in MAINTAINERS file since that is up for
debate
* Minor rebase cleanup
* Moved driver logic under drivers/hid/rust
v2->v3:
* Implemented AlwaysRefCounted trait using embedded struct device's
reference counts instead of the separate reference counter in struct
hid_device
* Used &raw mut as appropriate
* Binded include/linux/device.h for get_device and put_device
* Cleaned up various comment related formatting
* Minified dev_err! format string
* Updated Group enum to be repr(u16)
* Implemented From<u16> trait for Group
* Added TODO comment when const_trait_impl stabilizes
* Made group getter functions return a Group variant instead of a raw
number
* Made sure example code builds
v1->v2:
* Binded drivers/hid/hid-ids.h for use in Rust drivers
* Remove pre-emptive referencing of a C HID driver instance before
it is fully initialized in the driver registration path
* Moved static getters to generic Device trait implementation, so
they can be used by all device::DeviceContext
* Use core macros for supporting DeviceContext transitions
* Implemented the AlwaysRefCounted and AsRef traits
* Make use for dev_err! as appropriate
RFC->v1:
* Use Danilo's core infrastructure
* Account for HID device groups
* Remove probe and remove callbacks
* Implement report_fixup support
* Properly comment code including SAFETY comments
MAINTAINERS | 8 +
drivers/hid/Kconfig | 2 +
drivers/hid/rust/Kconfig | 12 +
rust/bindings/bindings_helper.h | 3 +
rust/kernel/hid.rs | 497 ++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 2 +
6 files changed, 524 insertions(+)
create mode 100644 drivers/hid/rust/Kconfig
create mode 100644 rust/kernel/hid.rs
diff --git a/MAINTAINERS b/MAINTAINERS
index cd7ff55b5d32..dc597bfe1a54 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10850,6 +10850,14 @@ F: include/uapi/linux/hid*
F: samples/hid/
F: tools/testing/selftests/hid/
+HID CORE LAYER [RUST]
+M: Rahul Rameshbabu <sergeantsagara@protonmail.com>
+R: Benjamin Tissoires <bentiss@kernel.org>
+L: linux-input@vger.kernel.org
+S: Maintained
+F: drivers/hid/rust/*.rs
+F: rust/kernel/hid.rs
+
HID LOGITECH DRIVERS
R: Filipe Laíns <lains@riseup.net>
L: linux-input@vger.kernel.org
diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 79997553d8f9..073771d95966 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -1420,6 +1420,8 @@ endmenu
source "drivers/hid/bpf/Kconfig"
+source "drivers/hid/rust/Kconfig"
+
source "drivers/hid/i2c-hid/Kconfig"
source "drivers/hid/intel-ish-hid/Kconfig"
diff --git a/drivers/hid/rust/Kconfig b/drivers/hid/rust/Kconfig
new file mode 100644
index 000000000000..d3247651829e
--- /dev/null
+++ b/drivers/hid/rust/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menu "Rust HID support"
+
+config RUST_HID_ABSTRACTIONS
+ bool "Rust HID abstractions support"
+ depends on RUST
+ depends on HID=y
+ help
+ Adds support needed for HID drivers written in Rust. It provides a
+ wrapper around the C hid core.
+
+endmenu # Rust HID support
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index 4ad9add117ea..773468788d98 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -46,6 +46,7 @@
#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/cred.h>
+#include <linux/device.h>
#include <linux/device/faux.h>
#include <linux/dma-mapping.h>
#include <linux/errname.h>
@@ -53,6 +54,8 @@
#include <linux/file.h>
#include <linux/firmware.h>
#include <linux/fs.h>
+#include <linux/hid.h>
+#include "../../drivers/hid/hid-ids.h"
#include <linux/ioport.h>
#include <linux/jiffies.h>
#include <linux/jump_label.h>
diff --git a/rust/kernel/hid.rs b/rust/kernel/hid.rs
new file mode 100644
index 000000000000..588483bf7204
--- /dev/null
+++ b/rust/kernel/hid.rs
@@ -0,0 +1,497 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2025 Rahul Rameshbabu <sergeantsagara@protonmail.com>
+
+//! Abstractions for the HID interface.
+//!
+//! C header: [`include/linux/hid.h`](srctree/include/linux/hid.h)
+
+use crate::{device, device_id::RawDeviceId, driver, error::*, prelude::*, types::Opaque};
+use core::{
+ marker::PhantomData,
+ ptr::{addr_of_mut, NonNull},
+};
+
+/// Indicates the item is static read-only.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_CONSTANT: u8 = bindings::HID_MAIN_ITEM_CONSTANT as u8;
+
+/// Indicates the item represents data from a physical control.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_VARIABLE: u8 = bindings::HID_MAIN_ITEM_VARIABLE as u8;
+
+/// Indicates the item should be treated as a relative change from the previous
+/// report.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_RELATIVE: u8 = bindings::HID_MAIN_ITEM_RELATIVE as u8;
+
+/// Indicates the item should wrap around when reaching the extreme high or
+/// extreme low values.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_WRAP: u8 = bindings::HID_MAIN_ITEM_WRAP as u8;
+
+/// Indicates the item should wrap around when reaching the extreme high or
+/// extreme low values.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_NONLINEAR: u8 = bindings::HID_MAIN_ITEM_NONLINEAR as u8;
+
+/// Indicates whether the control has a preferred state it will physically
+/// return to without user intervention.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_NO_PREFERRED: u8 = bindings::HID_MAIN_ITEM_NO_PREFERRED as u8;
+
+/// Indicates whether the control has a physical state where it will not send
+/// any reports.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_NULL_STATE: u8 = bindings::HID_MAIN_ITEM_NULL_STATE as u8;
+
+/// Indicates whether the control requires host system logic to change state.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_VOLATILE: u8 = bindings::HID_MAIN_ITEM_VOLATILE as u8;
+
+/// Indicates whether the item is fixed size or a variable buffer of bytes.
+///
+/// Refer to [Device Class Definition for HID 1.11]
+/// Section 6.2.2.5 Input, Output, and Feature Items.
+///
+/// [Device Class Definition for HID 1.11]: https://www.usb.org/sites/default/files/hid1_11.pdf
+pub const MAIN_ITEM_BUFFERED_BYTE: u8 = bindings::HID_MAIN_ITEM_BUFFERED_BYTE as u8;
+
+/// HID device groups are intended to help categories HID devices based on a set
+/// of common quirks and logic that they will require to function correctly.
+#[repr(u16)]
+pub enum Group {
+ /// Used to match a device against any group when probing.
+ Any = bindings::HID_GROUP_ANY as u16,
+
+ /// Indicates a generic device that should need no custom logic from the
+ /// core HID stack.
+ Generic = bindings::HID_GROUP_GENERIC as u16,
+
+ /// Maps multitouch devices to hid-multitouch instead of hid-generic.
+ Multitouch = bindings::HID_GROUP_MULTITOUCH as u16,
+
+ /// Used for autodetecing and mapping of HID sensor hubs to
+ /// hid-sensor-hub.
+ SensorHub = bindings::HID_GROUP_SENSOR_HUB as u16,
+
+ /// Used for autodetecing and mapping Win 8 multitouch devices to set the
+ /// needed quirks.
+ MultitouchWin8 = bindings::HID_GROUP_MULTITOUCH_WIN_8 as u16,
+
+ // Vendor-specific device groups.
+ /// Used to distinguish Synpatics touchscreens from other products. The
+ /// touchscreens will be handled by hid-multitouch instead, while everything
+ /// else will be managed by hid-rmi.
+ RMI = bindings::HID_GROUP_RMI as u16,
+
+ /// Used for hid-core handling to automatically identify Wacom devices and
+ /// have them probed by hid-wacom.
+ Wacom = bindings::HID_GROUP_WACOM as u16,
+
+ /// Used by logitech-djreceiver and logitech-djdevice to autodetect if
+ /// devices paied to the DJ receivers are DJ devices and handle them with
+ /// the device driver.
+ LogitechDJDevice = bindings::HID_GROUP_LOGITECH_DJ_DEVICE as u16,
+
+ /// Since the Valve Steam Controller only has vendor-specific usages,
+ /// prevent hid-generic from parsing its reports since there would be
+ /// nothing hid-generic could do for the device.
+ Steam = bindings::HID_GROUP_STEAM as u16,
+
+ /// Used to differentiate 27 Mhz frequency Logitech DJ devices from other
+ /// Logitech DJ devices.
+ Logitech27MHzDevice = bindings::HID_GROUP_LOGITECH_27MHZ_DEVICE as u16,
+
+ /// Used for autodetecting and mapping Vivaldi devices to hid-vivaldi.
+ Vivaldi = bindings::HID_GROUP_VIVALDI as u16,
+}
+
+// TODO: use `const_trait_impl` once stabilized:
+//
+// ```
+// impl const From<Group> for u16 {
+// /// [`Group`] variants are represented by [`u16`] values.
+// fn from(value: Group) -> Self {
+// value as Self
+// }
+// }
+// ```
+impl Group {
+ /// Internal function used to convert [`Group`] variants into [`u16`].
+ const fn into(self) -> u16 {
+ self as u16
+ }
+}
+
+impl From<u16> for Group {
+ /// [`u16`] values can be safely converted to [`Group`] variants.
+ fn from(value: u16) -> Self {
+ match value.into() {
+ bindings::HID_GROUP_GENERIC => Group::Generic,
+ bindings::HID_GROUP_MULTITOUCH => Group::Multitouch,
+ bindings::HID_GROUP_SENSOR_HUB => Group::SensorHub,
+ bindings::HID_GROUP_MULTITOUCH_WIN_8 => Group::MultitouchWin8,
+ bindings::HID_GROUP_RMI => Group::RMI,
+ bindings::HID_GROUP_WACOM => Group::Wacom,
+ bindings::HID_GROUP_LOGITECH_DJ_DEVICE => Group::LogitechDJDevice,
+ bindings::HID_GROUP_STEAM => Group::Steam,
+ bindings::HID_GROUP_LOGITECH_27MHZ_DEVICE => Group::Logitech27MHzDevice,
+ bindings::HID_GROUP_VIVALDI => Group::Vivaldi,
+ _ => Group::Any,
+ }
+ }
+}
+
+/// The HID device representation.
+///
+/// This structure represents the Rust abstraction for a C `struct hid_device`.
+/// The implementation abstracts the usage of an already existing C `struct
+/// hid_device` within Rust code that we get passed from the C side.
+///
+/// # Invariants
+///
+/// A [`Device`] instance represents a valid `struct hid_device` created by the
+/// C portion of the kernel.
+#[repr(transparent)]
+pub struct Device<Ctx: device::DeviceContext = device::Normal>(
+ Opaque<bindings::hid_device>,
+ PhantomData<Ctx>,
+);
+
+impl<Ctx: device::DeviceContext> Device<Ctx> {
+ fn as_raw(&self) -> *mut bindings::hid_device {
+ self.0.get()
+ }
+
+ /// Returns the HID transport bus ID.
+ pub fn bus(&self) -> u16 {
+ // SAFETY: `self.as_raw` is a valid pointer to a `struct hid_device`
+ unsafe { *self.as_raw() }.bus
+ }
+
+ /// Returns the HID report group.
+ pub fn group(&self) -> Group {
+ // SAFETY: `self.as_raw` is a valid pointer to a `struct hid_device`
+ unsafe { *self.as_raw() }.group.into()
+ }
+
+ /// Returns the HID vendor ID.
+ pub fn vendor(&self) -> u32 {
+ // SAFETY: `self.as_raw` is a valid pointer to a `struct hid_device`
+ unsafe { *self.as_raw() }.vendor
+ }
+
+ /// Returns the HID product ID.
+ pub fn product(&self) -> u32 {
+ // SAFETY: `self.as_raw` is a valid pointer to a `struct hid_device`
+ unsafe { *self.as_raw() }.product
+ }
+}
+
+// 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 crate::types::AlwaysRefCounted for Device {
+ fn inc_ref(&self) {
+ // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero.
+ unsafe { bindings::get_device(&raw mut (*self.as_raw()).dev) };
+ }
+
+ unsafe fn dec_ref(obj: NonNull<Self>) {
+ // SAFETY: The safety requirements guarantee that the refcount is non-zero.
+ unsafe { bindings::put_device(&raw mut (*obj.cast::<bindings::hid_device>().as_ptr()).dev) }
+ }
+}
+
+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 hid_device`.
+ let dev = unsafe { addr_of_mut!((*self.as_raw()).dev) };
+
+ // SAFETY: `dev` points to a valid `struct device`.
+ unsafe { device::Device::from_raw(dev) }
+ }
+}
+
+/// Abstraction for the HID device ID structure `struct hid_device_id`.
+#[repr(transparent)]
+#[derive(Clone, Copy)]
+pub struct DeviceId(bindings::hid_device_id);
+
+impl DeviceId {
+ /// Equivalent to C's `HID_USB_DEVICE` macro.
+ ///
+ /// Create a new `hid::DeviceId` from a group, vendor ID, and device ID
+ /// number.
+ pub const fn new_usb(group: Group, vendor: u32, product: u32) -> Self {
+ Self(bindings::hid_device_id {
+ bus: 0x3, // BUS_USB
+ group: group.into(),
+ vendor,
+ product,
+ driver_data: 0,
+ })
+ }
+
+ /// Returns the HID transport bus ID.
+ pub fn bus(&self) -> u16 {
+ self.0.bus
+ }
+
+ /// Returns the HID report group.
+ pub fn group(&self) -> Group {
+ self.0.group.into()
+ }
+
+ /// Returns the HID vendor ID.
+ pub fn vendor(&self) -> u32 {
+ self.0.vendor
+ }
+
+ /// Returns the HID product ID.
+ pub fn product(&self) -> u32 {
+ self.0.product
+ }
+}
+
+// SAFETY:
+// * `DeviceId` is a `#[repr(transparent)` wrapper of `hid_device_id` and does not add
+// additional invariants, so it's safe to transmute to `RawType`.
+// * `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field.
+unsafe impl RawDeviceId for DeviceId {
+ type RawType = bindings::hid_device_id;
+}
+
+/// [`IdTable`] type for HID.
+pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;
+
+/// Create a HID [`IdTable`] with its alias for modpost.
+#[macro_export]
+macro_rules! hid_device_table {
+ ($table_name:ident, $module_table_name:ident, $id_info_type: ty, $table_data: expr) => {
+ const $table_name: $crate::device_id::IdArray<
+ $crate::hid::DeviceId,
+ $id_info_type,
+ { $table_data.len() },
+ > = $crate::device_id::IdArray::new($table_data);
+
+ $crate::module_device_table!("hid", $module_table_name, $table_name);
+ };
+}
+
+/// The HID driver trait.
+///
+/// # Examples
+///
+/// ```
+/// use kernel::{bindings, device, hid};
+///
+/// struct MyDriver;
+///
+/// kernel::hid_device_table!(
+/// HID_TABLE,
+/// MODULE_HID_TABLE,
+/// <MyDriver as hid::Driver>::IdInfo,
+/// [(
+/// hid::DeviceId::new_usb(
+/// hid::Group::Steam,
+/// bindings::USB_VENDOR_ID_VALVE,
+/// bindings::USB_DEVICE_ID_STEAM_DECK,
+/// ),
+/// (),
+/// )]
+/// );
+///
+/// #[vtable]
+/// impl hid::Driver for MyDriver {
+/// type IdInfo = ();
+/// const ID_TABLE: hid::IdTable<Self::IdInfo> = &HID_TABLE;
+///
+/// /// This function is optional to implement.
+/// fn report_fixup<'a, 'b: 'a>(_hdev: &hid::Device<device::Core>, rdesc: &'b mut [u8]) -> &'a [u8] {
+/// // Perform some report descriptor fixup.
+/// rdesc
+/// }
+/// }
+/// ```
+/// Drivers must implement this trait in order to get a HID driver registered.
+/// Please refer to the `Adapter` documentation for an example.
+#[vtable]
+pub trait Driver: Send {
+ /// The type holding information about each device id supported by the driver.
+ // TODO: Use `associated_type_defaults` once stabilized:
+ //
+ // ```
+ // type IdInfo: 'static = ();
+ // ```
+ type IdInfo: 'static;
+
+ /// The table of device ids supported by the driver.
+ const ID_TABLE: IdTable<Self::IdInfo>;
+
+ /// Called before report descriptor parsing. Can be used to mutate the
+ /// report descriptor before the core HID logic processes the descriptor.
+ /// Useful for problematic report descriptors that prevent HID devices from
+ /// functioning correctly.
+ ///
+ /// Optional to implement.
+ fn report_fixup<'a, 'b: 'a>(_hdev: &Device<device::Core>, _rdesc: &'b mut [u8]) -> &'a [u8] {
+ build_error!(VTABLE_DEFAULT_ERROR)
+ }
+}
+
+/// An adapter for the registration of HID drivers.
+pub struct Adapter<T: Driver>(T);
+
+// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
+// a preceding call to `register` has been successful.
+unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
+ type RegType = bindings::hid_driver;
+
+ unsafe fn register(
+ hdrv: &Opaque<Self::RegType>,
+ name: &'static CStr,
+ module: &'static ThisModule,
+ ) -> Result {
+ // SAFETY: It's safe to set the fields of `struct hid_driver` on initialization.
+ unsafe {
+ (*hdrv.get()).name = name.as_char_ptr();
+ (*hdrv.get()).id_table = T::ID_TABLE.as_ptr();
+ (*hdrv.get()).report_fixup = if T::HAS_REPORT_FIXUP {
+ Some(Self::report_fixup_callback)
+ } else {
+ None
+ };
+ }
+
+ // SAFETY: `hdrv` is guaranteed to be a valid `RegType`
+ to_result(unsafe {
+ bindings::__hid_register_driver(hdrv.get(), module.0, name.as_char_ptr())
+ })
+ }
+
+ unsafe fn unregister(hdrv: &Opaque<Self::RegType>) {
+ // SAFETY: `hdrv` is guaranteed to be a valid `RegType`
+ unsafe { bindings::hid_unregister_driver(hdrv.get()) }
+ }
+}
+
+impl<T: Driver + 'static> Adapter<T> {
+ extern "C" fn report_fixup_callback(
+ hdev: *mut bindings::hid_device,
+ buf: *mut u8,
+ size: *mut kernel::ffi::c_uint,
+ ) -> *const u8 {
+ // SAFETY: The HID subsystem only ever calls the report_fixup callback
+ // with a valid pointer to a `struct hid_device`.
+ //
+ // INVARIANT: `hdev` is valid for the duration of
+ // `report_fixup_callback()`.
+ let hdev = unsafe { &*hdev.cast::<Device<device::Core>>() };
+
+ // SAFETY: The HID subsystem only ever calls the report_fixup callback
+ // with a valid pointer to a `kernel::ffi::c_uint`.
+ //
+ // INVARIANT: `size` is valid for the duration of
+ // `report_fixup_callback()`.
+ let buf_len: usize = match unsafe { *size }.try_into() {
+ Ok(len) => len,
+ Err(e) => {
+ dev_err!(
+ hdev.as_ref(),
+ "Cannot fix report description due to {}!\n",
+ e
+ );
+
+ return buf;
+ }
+ };
+
+ // Build a mutable Rust slice from `buf` and `size`.
+ //
+ // SAFETY: The HID subsystem only ever calls the `report_fixup callback`
+ // with a valid pointer to a `u8` buffer.
+ //
+ // INVARIANT: `buf` is valid for the duration of
+ // `report_fixup_callback()`.
+ let rdesc_slice = unsafe { core::slice::from_raw_parts_mut(buf, buf_len) };
+ let rdesc_slice = T::report_fixup(hdev, rdesc_slice);
+
+ match rdesc_slice.len().try_into() {
+ // SAFETY: The HID subsystem only ever calls the report_fixup
+ // callback with a valid pointer to a `kernel::ffi::c_uint`.
+ //
+ // INVARIANT: `size` is valid for the duration of
+ // `report_fixup_callback()`.
+ Ok(len) => unsafe { *size = len },
+ Err(e) => {
+ dev_err!(
+ hdev.as_ref(),
+ "Fixed report description will not be used due to {}!\n",
+ e
+ );
+
+ return buf;
+ }
+ }
+
+ rdesc_slice.as_ptr()
+ }
+}
+
+/// Declares a kernel module that exposes a single HID driver.
+///
+/// # Examples
+///
+/// ```ignore
+/// kernel::module_hid_driver! {
+/// type: MyDriver,
+/// name: "Module name",
+/// authors: ["Author name"],
+/// description: "Description",
+/// license: "GPL",
+/// }
+/// ```
+#[macro_export]
+macro_rules! module_hid_driver {
+ ($($f:tt)*) => {
+ $crate::module_driver!(<T>, $crate::hid::Adapter<T>, { $($f)* });
+ };
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 733f4d4e9bae..1e50912e81f6 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -89,6 +89,8 @@
pub mod firmware;
pub mod fmt;
pub mod fs;
+#[cfg(CONFIG_RUST_HID_ABSTRACTIONS)]
+pub mod hid;
pub mod init;
pub mod io;
pub mod ioctl;
--
2.51.0
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH v4 2/2] rust: hid: Glorious PC Gaming Race Model O and O- mice reference driver
2025-09-17 22:53 [PATCH v4 0/2] Initial work for Rust abstraction for HID device driver development Rahul Rameshbabu
2025-09-17 22:53 ` [PATCH v4 1/2] rust: core abstractions for HID drivers Rahul Rameshbabu
@ 2025-09-17 22:54 ` Rahul Rameshbabu
1 sibling, 0 replies; 3+ messages in thread
From: Rahul Rameshbabu @ 2025-09-17 22:54 UTC (permalink / raw)
To: linux-input, linux-kernel, rust-for-linux
Cc: a.hindborg, alex.gaynor, aliceryhl, benjamin.tissoires,
benno.lossin, bjorn3_gh, boqun.feng, dakr, db48x, gary, jikos,
ojeda, peter.hutterer, tmgross, Rahul Rameshbabu
Demonstrate how to perform a report fixup from a Rust HID driver. The mice
specify the const flag incorrectly in the consumer input report descriptor,
which leads to inputs being ignored. Correctly patch the report descriptor
for the Model O and O- mice.
Portions of the HID report post-fixup:
device 0:0
...
0x81, 0x06, // Input (Data,Var,Rel) 84
...
0x81, 0x06, // Input (Data,Var,Rel) 112
...
0x81, 0x06, // Input (Data,Var,Rel) 140
Signed-off-by: Rahul Rameshbabu <sergeantsagara@protonmail.com>
---
Notes:
Changelog:
v3->v4:
* Removed specifying tree in MAINTAINERS file since that is up for
debate
* Minor rebase cleanup
* Moved driver logic under drivers/hid/rust
* Use hex instead of decimal for the report descriptor comparisons
v2->v3:
* Fixed docstring formatting
* Updated MAINTAINERS file based on v1 and v2 discussion
v1->v2:
* Use vendor id and device id from drivers/hid/hid-ids.h bindings
* Make use for dev_err! as appropriate
MAINTAINERS | 6 +++
drivers/hid/hid-glorious.c | 2 +
drivers/hid/hid_glorious_rust.rs | 60 +++++++++++++++++++++++++++
drivers/hid/rust/Kconfig | 16 +++++++
drivers/hid/rust/Makefile | 6 +++
drivers/hid/rust/hid_glorious_rust.rs | 60 +++++++++++++++++++++++++++
6 files changed, 150 insertions(+)
create mode 100644 drivers/hid/hid_glorious_rust.rs
create mode 100644 drivers/hid/rust/Makefile
create mode 100644 drivers/hid/rust/hid_glorious_rust.rs
diff --git a/MAINTAINERS b/MAINTAINERS
index dc597bfe1a54..ad2f071efbaa 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10362,6 +10362,12 @@ L: platform-driver-x86@vger.kernel.org
S: Maintained
F: drivers/platform/x86/gigabyte-wmi.c
+GLORIOUS RUST DRIVER [RUST]
+M: Rahul Rameshbabu <sergeantsagara@protonmail.com>
+L: linux-input@vger.kernel.org
+S: Maintained
+F: drivers/hid/rust/hid_glorious_rust.rs
+
GNSS SUBSYSTEM
M: Johan Hovold <johan@kernel.org>
S: Maintained
diff --git a/drivers/hid/hid-glorious.c b/drivers/hid/hid-glorious.c
index 5bbd81248053..d7362852c20f 100644
--- a/drivers/hid/hid-glorious.c
+++ b/drivers/hid/hid-glorious.c
@@ -76,8 +76,10 @@ static int glorious_probe(struct hid_device *hdev,
}
static const struct hid_device_id glorious_devices[] = {
+#if !IS_ENABLED(CONFIG_HID_GLORIOUS_RUST)
{ HID_USB_DEVICE(USB_VENDOR_ID_SINOWEALTH,
USB_DEVICE_ID_GLORIOUS_MODEL_O) },
+#endif
{ HID_USB_DEVICE(USB_VENDOR_ID_SINOWEALTH,
USB_DEVICE_ID_GLORIOUS_MODEL_D) },
{ HID_USB_DEVICE(USB_VENDOR_ID_LAVIEW,
diff --git a/drivers/hid/hid_glorious_rust.rs b/drivers/hid/hid_glorious_rust.rs
new file mode 100644
index 000000000000..8cffc1c605dd
--- /dev/null
+++ b/drivers/hid/hid_glorious_rust.rs
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2025 Rahul Rameshbabu <sergeantsagara@protonmail.com>
+
+//! Rust reference HID driver for Glorious Model O and O- mice.
+
+use kernel::{self, bindings, device, hid, prelude::*};
+
+struct GloriousRust;
+
+kernel::hid_device_table!(
+ HID_TABLE,
+ MODULE_HID_TABLE,
+ <GloriousRust as hid::Driver>::IdInfo,
+ [(
+ hid::DeviceId::new_usb(
+ hid::Group::Generic,
+ bindings::USB_VENDOR_ID_SINOWEALTH,
+ bindings::USB_DEVICE_ID_GLORIOUS_MODEL_O,
+ ),
+ (),
+ )]
+);
+
+#[vtable]
+impl hid::Driver for GloriousRust {
+ type IdInfo = ();
+ const ID_TABLE: hid::IdTable<Self::IdInfo> = &HID_TABLE;
+
+ /// Fix the Glorious Model O and O- consumer input report descriptor to use
+ /// the variable and relative flag, while clearing the const flag.
+ ///
+ /// Without this fixup, inputs from the mice will be ignored.
+ fn report_fixup<'a, 'b: 'a>(hdev: &hid::Device<device::Core>, rdesc: &'b mut [u8]) -> &'a [u8] {
+ if rdesc.len() == 213
+ && (rdesc[84] == 129 && rdesc[85] == 3)
+ && (rdesc[112] == 129 && rdesc[113] == 3)
+ && (rdesc[140] == 129 && rdesc[141] == 3)
+ {
+ dev_info!(
+ hdev.as_ref(),
+ "patching Glorious Model O consumer control report descriptor\n"
+ );
+
+ rdesc[85] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+ rdesc[113] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+ rdesc[141] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+ }
+
+ rdesc
+ }
+}
+
+kernel::module_hid_driver! {
+ type: GloriousRust,
+ name: "GloriousRust",
+ authors: ["Rahul Rameshbabu <sergeantsagara@protonmail.com>"],
+ description: "Rust reference HID driver for Glorious Model O and O- mice",
+ license: "GPL",
+}
diff --git a/drivers/hid/rust/Kconfig b/drivers/hid/rust/Kconfig
index d3247651829e..d7a1bf26bed0 100644
--- a/drivers/hid/rust/Kconfig
+++ b/drivers/hid/rust/Kconfig
@@ -9,4 +9,20 @@ config RUST_HID_ABSTRACTIONS
Adds support needed for HID drivers written in Rust. It provides a
wrapper around the C hid core.
+if RUST_HID_ABSTRACTIONS
+
+menu "Special HID drivers"
+
+config HID_GLORIOUS_RUST
+ tristate "Glorious O and O- mice Rust reference driver"
+ depends on USB_HID
+ depends on RUST_HID_ABSTRACTIONS
+ help
+ Support for Glorious PC Gaming Race O and O- mice
+ in Rust.
+
+endmenu # Special HID drivers
+
+endif # RUST_HID_ABSTRACTIONS
+
endmenu # Rust HID support
diff --git a/drivers/hid/rust/Makefile b/drivers/hid/rust/Makefile
new file mode 100644
index 000000000000..6676030a2f87
--- /dev/null
+++ b/drivers/hid/rust/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for Rust HID support
+#
+
+obj-$(CONFIG_HID_GLORIOUS_RUST) += hid_glorious_rust.o
diff --git a/drivers/hid/rust/hid_glorious_rust.rs b/drivers/hid/rust/hid_glorious_rust.rs
new file mode 100644
index 000000000000..dfc3f2323b60
--- /dev/null
+++ b/drivers/hid/rust/hid_glorious_rust.rs
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2025 Rahul Rameshbabu <sergeantsagara@protonmail.com>
+
+//! Rust reference HID driver for Glorious Model O and O- mice.
+
+use kernel::{self, bindings, device, hid, prelude::*};
+
+struct GloriousRust;
+
+kernel::hid_device_table!(
+ HID_TABLE,
+ MODULE_HID_TABLE,
+ <GloriousRust as hid::Driver>::IdInfo,
+ [(
+ hid::DeviceId::new_usb(
+ hid::Group::Generic,
+ bindings::USB_VENDOR_ID_SINOWEALTH,
+ bindings::USB_DEVICE_ID_GLORIOUS_MODEL_O,
+ ),
+ (),
+ )]
+);
+
+#[vtable]
+impl hid::Driver for GloriousRust {
+ type IdInfo = ();
+ const ID_TABLE: hid::IdTable<Self::IdInfo> = &HID_TABLE;
+
+ /// Fix the Glorious Model O and O- consumer input report descriptor to use
+ /// the variable and relative flag, while clearing the const flag.
+ ///
+ /// Without this fixup, inputs from the mice will be ignored.
+ fn report_fixup<'a, 'b: 'a>(hdev: &hid::Device<device::Core>, rdesc: &'b mut [u8]) -> &'a [u8] {
+ if rdesc.len() == 213
+ && (rdesc[84] == 0x81 && rdesc[85] == 0x3)
+ && (rdesc[112] == 0x81 && rdesc[113] == 0x3)
+ && (rdesc[140] == 0x81 && rdesc[141] == 0x3)
+ {
+ dev_info!(
+ hdev.as_ref(),
+ "patching Glorious Model O consumer control report descriptor\n"
+ );
+
+ rdesc[85] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+ rdesc[113] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+ rdesc[141] = hid::MAIN_ITEM_VARIABLE | hid::MAIN_ITEM_RELATIVE;
+ }
+
+ rdesc
+ }
+}
+
+kernel::module_hid_driver! {
+ type: GloriousRust,
+ name: "GloriousRust",
+ authors: ["Rahul Rameshbabu <sergeantsagara@protonmail.com>"],
+ description: "Rust reference HID driver for Glorious Model O and O- mice",
+ license: "GPL",
+}
--
2.51.0
^ permalink raw reply related [flat|nested] 3+ messages in thread