[PATCH 3/3] input: joystick: stinger: port Gravis Stinger driver to safe Rust

[clicedvly768 <harepro29@gmail.com>]

Rewrite the legacy Gravis Stinger serial gamepad driver in safe Rust,
replacing drivers/input/joystick/stinger.c with stinger.rs.

The new implementation:
- Uses the newly introduced `kernel::input` and `kernel::serio`
  abstractions.
- Contains zero `unsafe` blocks in the driver code itself.
- Preserves full protocol compatibility with the Gravis Stinger hardware
  (9600 baud, 8N1, 4-byte packet format with 10 buttons and 2 axes).
- Adds `depends on RUST` to CONFIG_JOYSTICK_STINGER in Kconfig.

Signed-off-by: clicedvly768 <harepro29@gmail.com>
---
 drivers/input/joystick/Kconfig    |   1 +
 drivers/input/joystick/stinger.c  | 191 ------------------------------
 drivers/input/joystick/stinger.rs | 174 +++++++++++++++++++++++++++
 3 files changed, 175 insertions(+), 191 deletions(-)
 delete mode 100644 drivers/input/joystick/stinger.c
 create mode 100644 drivers/input/joystick/stinger.rs

diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
index 7755e5b454d2..e672a3bc6dcc 100644
--- a/drivers/input/joystick/Kconfig
+++ b/drivers/input/joystick/Kconfig
@@ -188,6 +188,7 @@ config JOYSTICK_SPACEBALL
 	  module will be called spaceball.
 
 config JOYSTICK_STINGER
+	depends on RUST
 	tristate "Gravis Stinger gamepad"
 	select SERIO
 	help
diff --git a/drivers/input/joystick/stinger.c b/drivers/input/joystick/stinger.c
deleted file mode 100644
index 011f9b137dca..000000000000
--- a/drivers/input/joystick/stinger.c
+++ /dev/null
@@ -1,191 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- *  Copyright (c) 2000-2001 Vojtech Pavlik
- *  Copyright (c) 2000 Mark Fletcher
- */
-
-/*
- * Gravis Stinger gamepad driver for Linux
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/input.h>
-#include <linux/serio.h>
-
-#define DRIVER_DESC	"Gravis Stinger gamepad driver"
-
-MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
-MODULE_DESCRIPTION(DRIVER_DESC);
-MODULE_LICENSE("GPL");
-
-/*
- * Constants.
- */
-
-#define STINGER_MAX_LENGTH 8
-
-/*
- * Per-Stinger data.
- */
-
-struct stinger {
-	struct input_dev *dev;
-	int idx;
-	unsigned char data[STINGER_MAX_LENGTH];
-	char phys[32];
-};
-
-/*
- * stinger_process_packet() decodes packets the driver receives from the
- * Stinger. It updates the data accordingly.
- */
-
-static void stinger_process_packet(struct stinger *stinger)
-{
-	struct input_dev *dev = stinger->dev;
-	unsigned char *data = stinger->data;
-
-	if (!stinger->idx) return;
-
-	input_report_key(dev, BTN_A,	  ((data[0] & 0x20) >> 5));
-	input_report_key(dev, BTN_B,	  ((data[0] & 0x10) >> 4));
-	input_report_key(dev, BTN_C,	  ((data[0] & 0x08) >> 3));
-	input_report_key(dev, BTN_X,	  ((data[0] & 0x04) >> 2));
-	input_report_key(dev, BTN_Y,	  ((data[3] & 0x20) >> 5));
-	input_report_key(dev, BTN_Z,	  ((data[3] & 0x10) >> 4));
-	input_report_key(dev, BTN_TL,     ((data[3] & 0x08) >> 3));
-	input_report_key(dev, BTN_TR,     ((data[3] & 0x04) >> 2));
-	input_report_key(dev, BTN_SELECT, ((data[3] & 0x02) >> 1));
-	input_report_key(dev, BTN_START,   (data[3] & 0x01));
-
-	input_report_abs(dev, ABS_X, (data[1] & 0x3F) - ((data[0] & 0x01) << 6));
-	input_report_abs(dev, ABS_Y, ((data[0] & 0x02) << 5) - (data[2] & 0x3F));
-
-	input_sync(dev);
-
-	return;
-}
-
-/*
- * stinger_interrupt() is called by the low level driver when characters
- * are ready for us. We then buffer them for further processing, or call the
- * packet processing routine.
- */
-
-static irqreturn_t stinger_interrupt(struct serio *serio,
-	unsigned char data, unsigned int flags)
-{
-	struct stinger *stinger = serio_get_drvdata(serio);
-
-	/* All Stinger packets are 4 bytes */
-
-	if (stinger->idx < STINGER_MAX_LENGTH)
-		stinger->data[stinger->idx++] = data;
-
-	if (stinger->idx == 4) {
-		stinger_process_packet(stinger);
-		stinger->idx = 0;
-	}
-
-	return IRQ_HANDLED;
-}
-
-/*
- * stinger_disconnect() is the opposite of stinger_connect()
- */
-
-static void stinger_disconnect(struct serio *serio)
-{
-	struct stinger *stinger = serio_get_drvdata(serio);
-
-	serio_close(serio);
-	serio_set_drvdata(serio, NULL);
-	input_unregister_device(stinger->dev);
-	kfree(stinger);
-}
-
-/*
- * stinger_connect() is the routine that is called when someone adds a
- * new serio device that supports Stinger protocol and registers it as
- * an input device.
- */
-
-static int stinger_connect(struct serio *serio, struct serio_driver *drv)
-{
-	struct stinger *stinger;
-	struct input_dev *input_dev;
-	int err = -ENOMEM;
-
-	stinger = kmalloc_obj(*stinger);
-	input_dev = input_allocate_device();
-	if (!stinger || !input_dev)
-		goto fail1;
-
-	stinger->dev = input_dev;
-	snprintf(stinger->phys, sizeof(stinger->phys), "%s/serio0", serio->phys);
-
-	input_dev->name = "Gravis Stinger";
-	input_dev->phys = stinger->phys;
-	input_dev->id.bustype = BUS_RS232;
-	input_dev->id.vendor = SERIO_STINGER;
-	input_dev->id.product = 0x0001;
-	input_dev->id.version = 0x0100;
-	input_dev->dev.parent = &serio->dev;
-
-	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
-	input_dev->keybit[BIT_WORD(BTN_A)] = BIT_MASK(BTN_A) | BIT_MASK(BTN_B) |
-		BIT_MASK(BTN_C) | BIT_MASK(BTN_X) | BIT_MASK(BTN_Y) |
-		BIT_MASK(BTN_Z) | BIT_MASK(BTN_TL) | BIT_MASK(BTN_TR) |
-		BIT_MASK(BTN_START) | BIT_MASK(BTN_SELECT);
-	input_set_abs_params(input_dev, ABS_X, -64, 64, 0, 4);
-	input_set_abs_params(input_dev, ABS_Y, -64, 64, 0, 4);
-
-	serio_set_drvdata(serio, stinger);
-
-	err = serio_open(serio, drv);
-	if (err)
-		goto fail2;
-
-	err = input_register_device(stinger->dev);
-	if (err)
-		goto fail3;
-
-	return 0;
-
- fail3:	serio_close(serio);
- fail2:	serio_set_drvdata(serio, NULL);
- fail1:	input_free_device(input_dev);
-	kfree(stinger);
-	return err;
-}
-
-/*
- * The serio driver structure.
- */
-
-static const struct serio_device_id stinger_serio_ids[] = {
-	{
-		.type	= SERIO_RS232,
-		.proto	= SERIO_STINGER,
-		.id	= SERIO_ANY,
-		.extra	= SERIO_ANY,
-	},
-	{ 0 }
-};
-
-MODULE_DEVICE_TABLE(serio, stinger_serio_ids);
-
-static struct serio_driver stinger_drv = {
-	.driver		= {
-		.name	= "stinger",
-	},
-	.description	= DRIVER_DESC,
-	.id_table	= stinger_serio_ids,
-	.interrupt	= stinger_interrupt,
-	.connect	= stinger_connect,
-	.disconnect	= stinger_disconnect,
-};
-
-module_serio_driver(stinger_drv);
diff --git a/drivers/input/joystick/stinger.rs b/drivers/input/joystick/stinger.rs
new file mode 100644
index 000000000000..daa199463631
--- /dev/null
+++ b/drivers/input/joystick/stinger.rs
@@ -0,0 +1,174 @@
+// 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,
+    input::{bus, event_type, AllocatedDevice, RegisteredDevice},
+    prelude::*,
+    serio,
+    types::ForeignOwnable,
+};
+
+const DRIVER_NAME: &CStr = c"stinger";
+const DRIVER_DESC: &CStr = c"Gravis Stinger gamepad";
+
+const STINGER_MAX_LENGTH: usize = 8;
+
+/// 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();
+    }
+}
+
+/// The safe serio driver implementation.
+struct StingerDriver;
+
+impl serio::Driver for StingerDriver {
+    type Data = KBox<Stinger>;
+
+    const ID_TABLE: &'static [serio::DeviceId] = &[
+        serio::DeviceId::new(
+            bindings::SERIO_RS232 as u8,
+            bindings::SERIO_ANY as u8,
+            bindings::SERIO_ANY as u8,
+            bindings::SERIO_STINGER as u8,
+        ),
+        serio::DeviceId::new(0, 0, 0, 0),
+    ];
+
+    fn connect(dev: &mut serio::Device) -> Result<Self::Data> {
+        let mut input_alloc = AllocatedDevice::new()?;
+
+        input_alloc.set_name(DRIVER_DESC);
+        input_alloc.set_phys(dev.phys().as_ptr());
+        input_alloc.set_id(bus::RS232, bindings::SERIO_STINGER as u16, 0x0001, 0x0100);
+
+        // 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 joystick with flat margin of 4
+        input_alloc.set_capability(event_type::ABS, bindings::ABS_X);
+        input_alloc.set_capability(event_type::ABS, bindings::ABS_Y);
+        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,
+    ) -> serio::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;
+        }
+
+        serio::IrqReturn::Handled
+    }
+
+    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)?;
+        pr_info!("Gravis Stinger safe Rust driver initialized\n");
+        Ok(Self { _reg: reg })
+    }
+}
-- 
2.56.0