14 Commits

7 changed files with 610 additions and 395 deletions

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@@ -1,5 +1,6 @@
# Device Drivers
---------------------------------- Device Driver
=============
This repository contains Linux **kernel modules** (``.ko``) that implement low-level USB input drivers and expose device events through the Linux **input subsystem** (evdev). This repository contains Linux **kernel modules** (``.ko``) that implement low-level USB input drivers and expose device events through the Linux **input subsystem** (evdev).
@@ -9,7 +10,6 @@ A helper tool (``usb_driver_manager.py``) is included to make it easier to:
- unbind/bind a selected interface to a chosen driver during development - unbind/bind a selected interface to a chosen driver during development
## Drivers ## Drivers
----------
### Mouse driver (``mouse/``) ### Mouse driver (``mouse/``)
USB HID boot-protocol mouse driver. USB HID boot-protocol mouse driver.
@@ -37,7 +37,6 @@ make
After building, the module (``*.ko``) is typically placed under ``build/`` by the provided Makefiles. After building, the module (``*.ko``) is typically placed under ``build/`` by the provided Makefiles.
## USB Driver Manager ## USB Driver Manager
---------------------
**Usage examples:** **Usage examples:**
```bash ```bash
@@ -55,7 +54,7 @@ sudo python3 usb_driver_manager.py ./mouse/build ./g29_media_usb/build
4. Confirm; the tool unbinds the current driver, reloads the module if needed, and binds the chosen interface. 4. Confirm; the tool unbinds the current driver, reloads the module if needed, and binds the chosen interface.
## Testing ## Testing
----------
After binding the driver, use ``evtest`` to confirm key events: After binding the driver, use ``evtest`` to confirm key events:
```bash ```bash
sudo evtest sudo evtest

14
g29-wheel/Makefile Normal file
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@@ -0,0 +1,14 @@
.PHONY: all clean install uninstall
obj-m += g29_usb.o
PWD := $(CURDIR)
all:
$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
mkdir -p build
-mv -f -- *.ko *.mod.c *.o .*.o *.mod modules.order .*.cmd *.symvers build/
clean:
$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
rm -rf build

514
g29-wheel/g29_usb.c Normal file
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@@ -0,0 +1,514 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Logitech G29 -> Media Keys (USB interface driver)
*
* Proof-of-concept Linux kernel module for low-level programming course.
*
* This driver:
* - Binds to a Logitech G29 USB interface (VID/PID match)
* - Receives 12-byte input reports via an interrupt-IN URB
* - Parses the report into a normalized state (Stage A)
* - Translates selected signals into media key events (Stage B)
*
* Stage A is designed to remain stable across different mapping policies.
* Stage B is designed to be replaced/extended by swapping mapping tables
* or adding per-signal handler functions.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/input.h>
#include <linux/input.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/hid.h>
#include "g29_usb.h"
MODULE_AUTHOR("LLP group 16");
MODULE_DESCRIPTION("Logitech G29 USB driver");
MODULE_LICENSE("GPL");
enum g29_mode {
G29_MODE_MEDIA = 0,
G29_MODE_WASD = 1,
G29_MODE_MOUSE = 2,
};
static int mode = G29_MODE_MEDIA;
module_param(mode, int, 0644);
MODULE_PARM_DESC(mode, "Initial mode (0=MEDIA, 1=WASD, 2=MOUSE)");
/* Steering curve exponent (100 = linear, 200 = squared, 150 = ^1.5)
* Higher values reduce sensitivity at low steering angles.
*/
static int steer_curve = 100;
module_param(steer_curve, int, 0644);
MODULE_PARM_DESC(steer_curve, "Steering sensitivity curve (100=linear, 200=squared, default=200)");
static int steer_deadzone = 10;
module_param(steer_deadzone, int, 0644);
MODULE_PARM_DESC(steer_deadzone, "Steering deadzone radius from center (default=10)");
static int gas_curve = 100;
module_param(gas_curve, int, 0644);
MODULE_PARM_DESC(gas_curve, "Gas pedal sensitivity curve (100=linear, 200=squared, default=200)");
static int clutch_curve = 100;
module_param(clutch_curve, int, 0644);
MODULE_PARM_DESC(clutch_curve, "Clutch pedal sensitivity curve (100=linear, 200=squared, default=200)");
#define NORMALIZATION_PRECISION 1000
struct g29_keymap {
u32 mask;
unsigned short keycode;
};
static const struct g29_keymap media_mode_keymap[] = {
/* Red rotary = volume */
{G29_BTN_RED_CW, KEY_VOLUMEUP},
{G29_BTN_RED_CCW, KEY_VOLUMEDOWN},
/* Return = play/pause */
{G29_BTN_RETURN, KEY_PLAYPAUSE},
/* Plus/Minus = next/prev */
{G29_BTN_R1, KEY_NEXTSONG},
{G29_BTN_L1, KEY_PREVIOUSSONG},
};
static const struct g29_keymap mouse_mode_keymap[] = {
{G29_BTN_X, BTN_LEFT},
{G29_BTN_CIRCLE, BTN_RIGHT},
{G29_BTN_TRIANGLE, BTN_MIDDLE},
{G29_BTN_SQUARE, BTN_SIDE},
};
struct g29_dev {
char name[128];
char phys[64];
struct usb_device *udev;
struct input_dev *input;
struct urb *urb;
u8 *buf;
dma_addr_t buf_dma;
int maxp;
int interval;
int endpoint;
struct timer_list steer_timer;
struct timer_list mouse_timer;
u32 steer_phase_ms;
u32 phase_accumulator;
u32 gas_phase_accumulator;
u32 clutch_phase_accumulator;
enum g29_mode current_mode;
struct g29_state last;
};
static void g29_switch_mode(struct g29_dev *g29, enum g29_mode new_mode) {
if (g29->current_mode == new_mode)
return;
/* Stop timers when leaving modes */
if (g29->current_mode == G29_MODE_WASD) {
timer_delete_sync(&g29->steer_timer);
}
if (g29->current_mode == G29_MODE_MOUSE) {
timer_delete_sync(&g29->mouse_timer);
}
g29->current_mode = new_mode;
g29->phase_accumulator = 0;
g29->gas_phase_accumulator = 0;
g29->clutch_phase_accumulator = 0;
/* Start timers when entering modes */
if (new_mode == G29_MODE_WASD) {
mod_timer(&g29->steer_timer, jiffies + msecs_to_jiffies(1));
}
if (new_mode == G29_MODE_MOUSE) {
mod_timer(&g29->mouse_timer, jiffies + msecs_to_jiffies(10));
}
dev_info(&g29->udev->dev, "Switched to mode: %s\n",
new_mode == G29_MODE_MEDIA ? "MEDIA" :
new_mode == G29_MODE_WASD ? "WASD" : "MOUSE");
}
static void mouse_mode_timer_fn(struct timer_list *t) {
struct g29_dev *g29 = timer_container_of(g29, t, mouse_timer);
const int rot = le16_to_cpu(g29->last.rot_le);
int gas_pressure = G29_PEDAL_RELEASED - g29->last.gas;
int clutch_pressure = G29_PEDAL_RELEASED - g29->last.clt;
/* Calculate speed: positive for forward (gas), negative for backward (clutch) */
int speed = gas_pressure - clutch_pressure;
/* Apply deadzone to steering */
int effective_rot = rot;
if (abs(rot - WHEEL_CENTER) <= steer_deadzone) {
effective_rot = WHEEL_CENTER;
}
/* Calculate angle from wheel rotation
* Map wheel rotation to angle:
* - Center (32768) = 0° (straight forward)
* - Full left (0) = -180° (reverse)
* - Full right (65535) = +180° (reverse)
* We normalize to -1000 to +1000 representing -π to +π radians
*/
int angle_normalized = ((effective_rot - WHEEL_CENTER) * 1000) / WHEEL_CENTER;
/* Clamp angle to prevent overflow */
if (angle_normalized > 1000) angle_normalized = 1000;
if (angle_normalized < -1000) angle_normalized = -1000;
/* Calculate movement components using better trigonometric approximations:
* dx = sin(angle) * speed
* dy = cos(angle) * speed
*
* sin(x) ≈ x - x³/6 (Taylor series)
* cos(x) ≈ 1 - x²/2 + x⁴/24 (Taylor series)
*
* For angle_normalized in [-1000, 1000] representing [-π, +π]:
* This gives us full reverse when fully steered
*/
long angle_cubed = ((long) angle_normalized * angle_normalized * angle_normalized) / 1000000;
int sin_approx = (angle_normalized * 1000 - angle_cubed / 6) / 1000;
long angle_squared = ((long) angle_normalized * angle_normalized) / 1000;
long angle_fourth = (angle_squared * angle_squared) / 1000;
int cos_approx = 1000 - angle_squared / 2 + angle_fourth / 24;
int dx = (sin_approx * speed) / 1000;
int dy = -(cos_approx * speed) / 1000; /* Negative because forward is -Y */
/* Scale down the movement for reasonable mouse speed */
int scaled_dx = dx / 50;
int scaled_dy = dy / 50;
/* Report mouse movement if there's any */
if (scaled_dx != 0 || scaled_dy != 0) {
input_report_rel(g29->input, REL_X, scaled_dx);
input_report_rel(g29->input, REL_Y, scaled_dy);
input_sync(g29->input);
}
/* Reschedule timer if still in mouse mode */
if (g29->current_mode == G29_MODE_MOUSE)
mod_timer(&g29->mouse_timer, jiffies + msecs_to_jiffies(10));
}
static void wasd_mode_timer_fn(struct timer_list *t) {
struct g29_dev *g29 = timer_container_of(g29, t, steer_timer);
const int period = 50;
const int rot = le16_to_cpu(g29->last.rot_le);
const int gas = 0xFF - g29->last.gas;
const int brk = 0xFF - g29->last.brk;
const int gas_duty = gas * period / 0x40;
input_report_key(g29->input, KEY_W, g29->gas_phase_accumulator < gas_duty);
g29->gas_phase_accumulator++;
g29->gas_phase_accumulator %= period;
input_report_key(g29->input, KEY_S, brk >= 0x80);
if (rot >= 0x7ff8 && rot <= 0x8008){
input_report_key(g29->input, KEY_A, 0);
input_report_key(g29->input, KEY_D, 0);
} else {
const int mag = rot < 0x8000 ? 0x8000 - rot : rot - 0x8000;
const int duty = mag * period / 0x3000;
const int k1 = rot > 0x8000 ? KEY_D : KEY_A;
const int k2 = rot > 0x8000 ? KEY_A : KEY_D;
input_report_key(g29->input, k2, 0);
input_report_key(g29->input, k1, g29->phase_accumulator < duty);
}
g29->phase_accumulator++;
g29->phase_accumulator %= period;
input_sync(g29->input);
if (g29->current_mode == G29_MODE_WASD)
mod_timer(&g29->steer_timer, jiffies + msecs_to_jiffies(1));
}
static void process_media_mode(const struct g29_dev *g29, const struct g29_state *cur, const struct g29_state *prev) {
const u32 buttons = le32_to_cpu(cur->buttons_le);
for (int i = 0; i < ARRAY_SIZE(media_mode_keymap); i++) {
const struct g29_keymap *k = &media_mode_keymap[i];
input_report_key(g29->input, k->keycode, !!(buttons & k->mask));
}
input_sync(g29->input);
}
static void process_wasd_mode(const struct g29_dev *g29, const struct g29_state *cur, const struct g29_state *prev) {
// WASD mode is handled by the timer function (g29_steer_timer_fn)
const u32 buttons = le32_to_cpu(cur->buttons_le);
input_report_key(g29->input, KEY_C, !!(buttons & G29_BTN_L1));
input_report_key(g29->input, KEY_SPACE, !!(buttons & G29_BTN_R1));
input_sync(g29->input);
}
static void process_mouse_mode(const struct g29_dev *g29, const struct g29_state *cur, const struct g29_state *prev) {
const u32 buttons = le32_to_cpu(cur->buttons_le);
const u32 pressed = le32_to_cpu(cur->buttons_le & ~prev->buttons_le);
//const u32 released = le32_to_cpu(~cur->buttons_le & prev->buttons_le);
for (int i = 0; i < ARRAY_SIZE(mouse_mode_keymap); i++) {
const struct g29_keymap *k = &mouse_mode_keymap[i];
input_report_key(g29->input, k->keycode, !!(buttons & k->mask));
}
if (pressed & G29_BTN_RED_CW) {
input_report_rel(g29->input, REL_WHEEL, 1);
} else if (pressed & G29_BTN_RED_CCW) {
input_report_rel(g29->input, REL_WHEEL, -1);
} else {
input_report_rel(g29->input, REL_WHEEL, 0);
}
input_sync(g29->input);
}
static void g29_check_mode_switch(struct g29_dev *g29, const struct g29_state *cur, const struct g29_state *prev) {
const u32 pressed = le32_to_cpu(cur->buttons_le & ~prev->buttons_le);
if (pressed & G29_BTN_SHARE) {
g29_switch_mode(g29, G29_MODE_MEDIA);
} else if (pressed & G29_BTN_OPTION) {
g29_switch_mode(g29, G29_MODE_WASD);
} else if (pressed & G29_BTN_PS3) {
g29_switch_mode(g29, G29_MODE_MOUSE);
}
}
static void g29_process_report(struct g29_dev *g29, const u8 *data, const unsigned int len) {
if (len < 12) return;
const struct g29_state *cur = (void *) data;
g29_check_mode_switch(g29, cur, &g29->last);
switch (g29->current_mode) {
case G29_MODE_MEDIA: process_media_mode(g29, cur, &g29->last); break;
case G29_MODE_WASD: process_wasd_mode(g29, cur, &g29->last); break;
case G29_MODE_MOUSE: process_mouse_mode(g29, cur, &g29->last);break;
}
g29->last = *cur;
}
static void g29_urb_complete(struct urb *urb) {
struct g29_dev *g29 = urb->context;
int ret;
switch (urb->status) {
case 0:
break; /* success */
case -ECONNRESET:
case -ENOENT:
case -ESHUTDOWN:
return; /* cancelled/disconnected */
default:
goto resubmit; /* transient error */
}
g29_process_report(g29, g29->buf, urb->actual_length);
resubmit:
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret)
dev_err(&g29->udev->dev, "usb_submit_urb failed: %d\n", ret);
}
static int g29_input_open(struct input_dev *input) {
struct g29_dev *g29 = input_get_drvdata(input);
g29->urb->dev = g29->udev;
if (usb_submit_urb(g29->urb, GFP_KERNEL))
return -EIO;
g29_switch_mode(g29, mode);
return 0;
}
static void g29_input_close(struct input_dev *input) {
struct g29_dev *g29 = input_get_drvdata(input);
if (g29->current_mode == G29_MODE_WASD)
timer_delete_sync(&g29->steer_timer);
if (g29->current_mode == G29_MODE_MOUSE)
timer_delete_sync(&g29->mouse_timer);
usb_kill_urb(g29->urb);
}
static int g29_probe(struct usb_interface *intf, const struct usb_device_id *id) {
struct usb_device *udev = interface_to_usbdev(intf);
int ret;
/* Find an interrupt IN endpoint capable of carrying the 12-byte report. */
struct usb_endpoint_descriptor *ep = NULL;
const struct usb_host_interface *alts = intf->cur_altsetting;
for (int i = 0; i < alts->desc.bNumEndpoints; i++) {
struct usb_endpoint_descriptor *d = &alts->endpoint[i].desc;
if (!usb_endpoint_is_int_in(d))
continue;
if (usb_maxpacket(udev, usb_rcvintpipe(udev, d->bEndpointAddress)) >= 12) {
ep = d;
break;
}
}
if (!ep) return -ENODEV;
struct g29_dev *g29;
if ((g29 = kzalloc(sizeof(*g29), GFP_KERNEL)) == NULL) {
return -ENOMEM;
}
struct input_dev *input;
if ((input = input_allocate_device()) == NULL) {
ret = -ENOMEM;
goto err_free_g29;
}
g29->udev = udev;
g29->input = input;
g29->endpoint = usb_endpoint_num(ep);
g29->maxp = usb_endpoint_maxp(ep);
g29->interval = ep->bInterval;
memset(&g29->last, 0, sizeof(g29->last));
g29->current_mode = mode; /* Initialize to module parameter */
timer_setup(&g29->steer_timer, wasd_mode_timer_fn, 0);
timer_setup(&g29->mouse_timer, mouse_mode_timer_fn, 0);
if ((g29->buf = usb_alloc_coherent(udev, g29->maxp, GFP_KERNEL, &g29->buf_dma)) == NULL) {
ret = -ENOMEM;
goto err_free_input;
}
if ((g29->urb = usb_alloc_urb(0, GFP_KERNEL)) == NULL) {
ret = -ENOMEM;
goto err_free_buf;
}
if (udev->manufacturer)
strscpy(g29->name, udev->manufacturer, sizeof(g29->name));
if (udev->product) {
if (udev->manufacturer)
strlcat(g29->name, " ", sizeof(g29->name));
strlcat(g29->name, udev->product, sizeof(g29->name));
}
if (!strlen(g29->name))
snprintf(g29->name, sizeof(g29->name),
"Logitech G29 USB %04x:%04x",
le16_to_cpu(udev->descriptor.idVendor),
le16_to_cpu(udev->descriptor.idProduct));
usb_make_path(udev, g29->phys, sizeof(g29->phys));
strlcat(g29->phys, "/input0", sizeof(g29->phys));
input->name = g29->name;
input->phys = g29->phys;
usb_to_input_id(udev, &input->id);
input->dev.parent = &intf->dev;
__set_bit(EV_KEY, input->evbit);
__set_bit(EV_REL, input->evbit);
// Media mode keys
input_set_capability(input, EV_KEY, KEY_VOLUMEUP);
input_set_capability(input, EV_KEY, KEY_VOLUMEDOWN);
input_set_capability(input, EV_KEY, KEY_PLAYPAUSE);
input_set_capability(input, EV_KEY, KEY_NEXTSONG);
input_set_capability(input, EV_KEY, KEY_PREVIOUSSONG);
// WASD mode keys
input_set_capability(input, EV_KEY, KEY_W);
input_set_capability(input, EV_KEY, KEY_A);
input_set_capability(input, EV_KEY, KEY_S);
input_set_capability(input, EV_KEY, KEY_D);
input_set_capability(input, EV_KEY, KEY_C);
input_set_capability(input, EV_KEY, KEY_SPACE);
// Mouse mode capabilities
input_set_capability(input, EV_KEY, BTN_LEFT);
input_set_capability(input, EV_KEY, BTN_RIGHT);
input_set_capability(input, EV_KEY, BTN_MIDDLE);
input_set_capability(input, EV_REL, REL_X);
input_set_capability(input, EV_REL, REL_Y);
input_set_capability(input, EV_REL, REL_WHEEL);
input_set_drvdata(input, g29);
input->open = g29_input_open;
input->close = g29_input_close;
usb_fill_int_urb(g29->urb, udev, usb_rcvintpipe(udev, ep->bEndpointAddress),
g29->buf, g29->maxp,
g29_urb_complete, g29, ep->bInterval);
g29->urb->transfer_dma = g29->buf_dma;
g29->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
if ((ret = input_register_device(input)) != 0) {
goto err_free_urb;
}
usb_set_intfdata(intf, g29);
dev_info(&intf->dev,
"G29 media driver bound (ep=%02x interval=%u)\n",
ep->bEndpointAddress, ep->bInterval);
return 0;
err_free_urb:
usb_free_urb(g29->urb);
err_free_buf:
usb_free_coherent(udev, g29->maxp, g29->buf, g29->buf_dma);
err_free_input:
input_free_device(input);
err_free_g29:
kfree(g29);
return ret;
}
static void g29_disconnect(struct usb_interface *intf) {
struct g29_dev *g29 = usb_get_intfdata(intf);
usb_set_intfdata(intf, NULL);
if (!g29) return;
usb_kill_urb(g29->urb);
input_unregister_device(g29->input);
usb_free_urb(g29->urb);
usb_free_coherent(interface_to_usbdev(intf), g29->maxp, g29->buf, g29->buf_dma);
kfree(g29);
dev_info(&intf->dev, "G29 driver disconnected\n");
}
static const struct usb_device_id g29_id_table[] = {
{USB_DEVICE(USB_VENDOR_ID_LOGITECH, USB_DEVICE_ID_LOGITECH_G29)},
{USB_DEVICE(USB_VENDOR_ID_LOGITECH, USB_DEVICE_ID_LOGITECH_G29_ALT)},
{}
};
MODULE_DEVICE_TABLE(usb, g29_id_table);
static struct usb_driver g29_driver = {
.name = "g29_usb",
.id_table = g29_id_table,
.probe = g29_probe,
.disconnect = g29_disconnect,
};
module_usb_driver(g29_driver);

76
g29-wheel/g29_usb.h Normal file
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@@ -0,0 +1,76 @@
/*
* Logitech G29 USB/HID Protocol Definitions
*/
#ifndef G29_USB_H
#define G29_USB_H
#include <linux/types.h>
#define USB_VENDOR_ID_LOGITECH 0x046d
#define USB_DEVICE_ID_LOGITECH_G29 0xc24f
#define USB_DEVICE_ID_LOGITECH_G29_ALT 0xc260
#define G29_BTN_X 0x00000010u
#define G29_BTN_SQUARE 0x00000020u
#define G29_BTN_CIRCLE 0x00000040u
#define G29_BTN_TRIANGLE 0x00000080u
#define G29_BTN_R1 0x00000100u
#define G29_BTN_L1 0x00000200u
#define G29_BTN_R2 0x00000400u
#define G29_BTN_L2 0x00000800u
#define G29_BTN_SHARE 0x00001000u
#define G29_BTN_OPTION 0x00002000u
#define G29_BTN_R3 0x00004000u
#define G29_BTN_L3 0x00008000u
#define G29_BTN_GEAR_1 0x00010000u
#define G29_BTN_GEAR_2 0x00020000u
#define G29_BTN_GEAR_3 0x00040000u
#define G29_BTN_GEAR_4 0x00080000u
#define G29_BTN_GEAR_5 0x00100000u
#define G29_BTN_GEAR_6 0x00200000u
#define G29_BTN_GEAR_REV 0x00400000u
#define G29_BTN_PLUS 0x00800000u
#define G29_BTN_MINUS 0x01000000u
#define G29_BTN_RED_CW 0x02000000u
#define G29_BTN_RED_CCW 0x04000000u
#define G29_BTN_RETURN 0x08000000u
#define G29_BTN_PS3 0x10000000u
#define G29_DPAD_MASK 0x0000000Eu
#define G29_DPAD_UP 0x00000000u
#define G29_DPAD_RIGHT 0x00000002u
#define G29_DPAD_DOWN 0x00000004u
#define G29_DPAD_LEFT 0x00000006u
#define G29_DPAD_NONE 0x00000008u
#define G29_WHEEL_MIN_ROTATION 0x0000
#define G29_WHEEL_MAX_ROTATION 0xFFFF
#define G29_PEDAL_RELEASED 0xFF
#define G29_PEDAL_PRESSED 0x00
#define G29_PEDAL_THRESHOLD 0x80
#define G29_GEARSHIFT_X_LEFT 0x30 /* Gears 1-2 */
#define G29_GEARSHIFT_X_CENTER 0x80 /* Gears 3-4 */
#define G29_GEARSHIFT_X_RIGHT 0xB0 /* Gears 5-6-R */
#define G29_GEARSHIFT_Y_TOP 0xD0 /* Gears 1-3-5 */
#define G29_GEARSHIFT_Y_BOTTOM 0x40 /* Gears 2-4-6-R */
#define G29_GEARSHIFT_Z_NEUTRAL 0x9C /* Neutral position */
#define G29_GEARSHIFT_Z_PRESSED 0xDC /* Pressed down */
#define WHEEL_CENTER 0x8000
#define WHEEL_MAX_DIST 0x8000
struct g29_state {
u32 buttons_le; /* Button bitmask (little-endian) */
u16 rot_le; /* Wheel rotation (little-endian) */
u8 gas; /* Gas pedal (0xFF=up, 0x00=down) */
u8 brk; /* Brake pedal (0xFF=up, 0x00=down) */
u8 clt; /* Clutch pedal (0xFF=up, 0x00=down) */
u8 gr_x; /* Gearshift X-axis */
u8 gr_y; /* Gearshift Y-axis */
u8 gr_z; /* Gearshift Z-axis */
} __packed;
#endif

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@@ -1,28 +0,0 @@
obj-m += g29_media_usb.o
PWD := $(CURDIR)
.PHONY: all clean install uninstall
all:
$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
mkdir -p build
mv -f *.ko build/ 2>/dev/null || true
clean:
$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
rm -rf build
install:
$(MAKE) -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules_install
depmod -a
uninstall:
@modpath=$$(modinfo -n g29_media_usb 2>/dev/null); \
if [ -z "$$modpath" ]; then \
echo "Module g29_media_usb not found via modinfo (not installed?)"; \
exit 1; \
fi; \
echo "Removing $$modpath"; \
rm -f "$$modpath"; \
depmod -a

View File

@@ -1,361 +0,0 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Logitech G29 -> Media Keys (USB interface driver)
*
* Proof-of-concept Linux kernel module for low-level programming course.
*
* This driver:
* - Binds to a Logitech G29 USB interface (VID/PID match)
* - Receives 12-byte input reports via an interrupt-IN URB
* - Parses the report into a normalized state (Stage A)
* - Translates selected signals into media key events (Stage B)
*
* Stage A is designed to remain stable across different mapping policies.
* Stage B is designed to be replaced/extended by swapping mapping tables
* or adding per-signal handler functions.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/input.h>
#include <linux/input.h>
#include <asm/unaligned.h>
MODULE_AUTHOR("LLP group 32");
MODULE_DESCRIPTION("Logitech G29 -> Media keys (USB driver)");
MODULE_LICENSE("GPL");
#define USB_VENDOR_ID_LOGITECH 0x046d
#define USB_DEVICE_ID_LOGITECH_G29 0xc24f
#define USB_DEVICE_ID_LOGITECH_G29_ALT 0xc260
#define G29_REPORT_LEN 12
/*
* Button masks
*/
#define G29_BTN_PLUS 0x00800000u
#define G29_BTN_MINUS 0x01000000u
#define G29_BTN_RED_CW 0x02000000u
#define G29_BTN_RED_CCW 0x04000000u
#define G29_BTN_RETURN 0x08000000u
#define G29_BTN_R1 0x00000100u
#define G29_BTN_L1 0x00000200u
enum g29_mode {
G29_MODE_MEDIA = 0,
};
static int mode = G29_MODE_MEDIA;
module_param(mode, int, 0444);
MODULE_PARM_DESC(mode, "Mapping mode (0=MEDIA)");
struct g29_state {
u32 buttons;
u16 rot;
u8 gas;
u8 brk;
u8 clt;
u8 grx;
u8 gry;
u8 grz;
};
/*
* Mapping table entry
*/
struct g29_keymap_edge {
u32 mask;
unsigned short keycode;
};
static const struct g29_keymap_edge g29_media_edge_map[] = {
/* Red rotary = volume */
{ G29_BTN_RED_CW, KEY_VOLUMEUP },
{ G29_BTN_RED_CCW, KEY_VOLUMEDOWN },
/* Return = play/pause */
{ G29_BTN_RETURN, KEY_PLAYPAUSE },
/* Plus/Minus = next/prev */
{ G29_BTN_R1, KEY_NEXTSONG },
{ G29_BTN_L1, KEY_PREVIOUSSONG },
};
struct g29_dev {
char name[128];
char phys[64];
struct usb_device *udev;
struct input_dev *input;
struct urb *urb;
u8 *buf;
dma_addr_t buf_dma;
struct g29_state last;
};
/* Parsing */
static bool g29_parse_report(struct g29_state *out, const u8 *data, int len)
{
if (len < G29_REPORT_LEN)
return false;
/* bytes 0..3 buttons bitfield */
out->buttons = get_unaligned_le32(&data[0]);
/* bytes 4..5 rotation */
out->rot = get_unaligned_le16(&data[4]);
out->gas = data[6];
out->brk = data[7];
out->clt = data[8];
out->grx = data[9];
out->gry = data[10];
out->grz = data[11];
return true;
}
/* Mapping policy */
static void g29_pulse_key(struct input_dev *input, unsigned short keycode)
{
/* A pulse is a press+release within one report frame. */
input_report_key(input, keycode, 1);
input_report_key(input, keycode, 0);
}
static void g29_apply_media_mode(struct g29_dev *g29,
const struct g29_state *prev,
const struct g29_state *cur)
{
u32 pressed = cur->buttons & ~prev->buttons;
size_t i;
for (i = 0; i < ARRAY_SIZE(g29_media_edge_map); i++) {
const struct g29_keymap_edge *e = &g29_media_edge_map[i];
if (pressed & e->mask)
g29_pulse_key(g29->input, e->keycode);
}
input_sync(g29->input);
}
static void g29_process_report(struct g29_dev *g29, const u8 *data, int len)
{
struct g29_state cur;
if (!g29_parse_report(&cur, data, len))
return;
switch (mode) {
case G29_MODE_MEDIA:
default:
g29_apply_media_mode(g29, &g29->last, &cur);
break;
}
g29->last = cur;
}
/* URB plumbing */
static void g29_urb_complete(struct urb *urb)
{
struct g29_dev *g29 = urb->context;
int ret;
switch (urb->status) {
case 0:
break; /* success */
case -ECONNRESET:
case -ENOENT:
case -ESHUTDOWN:
return; /* cancelled/disconnected */
default:
goto resubmit; /* transient error */
}
g29_process_report(g29, g29->buf, urb->actual_length);
resubmit:
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret)
dev_err(&g29->udev->dev, "usb_submit_urb failed: %d\n", ret);
}
static int g29_input_open(struct input_dev *input)
{
struct g29_dev *g29 = input_get_drvdata(input);
g29->urb->dev = g29->udev;
if (usb_submit_urb(g29->urb, GFP_KERNEL))
return -EIO;
return 0;
}
static void g29_input_close(struct input_dev *input)
{
struct g29_dev *g29 = input_get_drvdata(input);
usb_kill_urb(g29->urb);
}
/* USB driver binding */
static int g29_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
struct usb_device *udev = interface_to_usbdev(intf);
struct usb_host_interface *alts = intf->cur_altsetting;
struct usb_endpoint_descriptor *ep = NULL;
struct g29_dev *g29;
struct input_dev *input;
int i, pipe, maxp, error;
/* Find an interrupt IN endpoint capable of carrying the 12-byte report. */
for (i = 0; i < alts->desc.bNumEndpoints; i++) {
struct usb_endpoint_descriptor *cand = &alts->endpoint[i].desc;
if (!usb_endpoint_is_int_in(cand))
continue;
pipe = usb_rcvintpipe(udev, cand->bEndpointAddress);
maxp = usb_maxpacket(udev, pipe);
if (maxp >= G29_REPORT_LEN) {
ep = cand;
break;
}
}
if (!ep)
return -ENODEV;
g29 = kzalloc(sizeof(*g29), GFP_KERNEL);
if (!g29)
return -ENOMEM;
input = input_allocate_device();
if (!input) {
error = -ENOMEM;
goto err_free_g29;
}
g29->udev = udev;
g29->input = input;
memset(&g29->last, 0, sizeof(g29->last));
/* Allocate a fixed-size report buffer (12 bytes). */
g29->buf = usb_alloc_coherent(udev, G29_REPORT_LEN, GFP_KERNEL, &g29->buf_dma);
if (!g29->buf) {
error = -ENOMEM;
goto err_free_input;
}
g29->urb = usb_alloc_urb(0, GFP_KERNEL);
if (!g29->urb) {
error = -ENOMEM;
goto err_free_buf;
}
/* Build a friendly input device name. */
if (udev->manufacturer)
strscpy(g29->name, udev->manufacturer, sizeof(g29->name));
if (udev->product) {
if (udev->manufacturer)
strlcat(g29->name, " ", sizeof(g29->name));
strlcat(g29->name, udev->product, sizeof(g29->name));
}
if (!strlen(g29->name))
snprintf(g29->name, sizeof(g29->name),
"Logitech G29 Media %04x:%04x",
le16_to_cpu(udev->descriptor.idVendor),
le16_to_cpu(udev->descriptor.idProduct));
usb_make_path(udev, g29->phys, sizeof(g29->phys));
strlcat(g29->phys, "/input0", sizeof(g29->phys));
input->name = g29->name;
input->phys = g29->phys;
usb_to_input_id(udev, &input->id);
input->dev.parent = &intf->dev;
__set_bit(EV_KEY, input->evbit);
/* Advertise only the keys we emit in media mode. */
input_set_capability(input, EV_KEY, KEY_VOLUMEUP);
input_set_capability(input, EV_KEY, KEY_VOLUMEDOWN);
input_set_capability(input, EV_KEY, KEY_PLAYPAUSE);
input_set_capability(input, EV_KEY, KEY_NEXTSONG);
input_set_capability(input, EV_KEY, KEY_PREVIOUSSONG);
input_set_drvdata(input, g29);
input->open = g29_input_open;
input->close = g29_input_close;
pipe = usb_rcvintpipe(udev, ep->bEndpointAddress);
usb_fill_int_urb(g29->urb, udev, pipe,
g29->buf, G29_REPORT_LEN,
g29_urb_complete, g29, ep->bInterval);
g29->urb->transfer_dma = g29->buf_dma;
g29->urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
error = input_register_device(input);
if (error)
goto err_free_urb;
usb_set_intfdata(intf, g29);
dev_info(&intf->dev,
"G29 media driver bound (ep=%02x interval=%u)\n",
ep->bEndpointAddress, ep->bInterval);
return 0;
err_free_urb:
usb_free_urb(g29->urb);
err_free_buf:
usb_free_coherent(udev, G29_REPORT_LEN, g29->buf, g29->buf_dma);
err_free_input:
input_free_device(input);
err_free_g29:
kfree(g29);
return error;
}
static void g29_disconnect(struct usb_interface *intf)
{
struct g29_dev *g29 = usb_get_intfdata(intf);
usb_set_intfdata(intf, NULL);
if (!g29)
return;
usb_kill_urb(g29->urb);
input_unregister_device(g29->input);
usb_free_urb(g29->urb);
usb_free_coherent(interface_to_usbdev(intf), G29_REPORT_LEN,
g29->buf, g29->buf_dma);
kfree(g29);
dev_info(&intf->dev, "G29 media driver disconnected\n");
}
static const struct usb_device_id g29_id_table[] = {
{ USB_DEVICE(USB_VENDOR_ID_LOGITECH, USB_DEVICE_ID_LOGITECH_G29) },
{ USB_DEVICE(USB_VENDOR_ID_LOGITECH, USB_DEVICE_ID_LOGITECH_G29_ALT) },
{ }
};
MODULE_DEVICE_TABLE(usb, g29_id_table);
static struct usb_driver g29_driver = {
.name = "g29_media_usb",
.probe = g29_probe,
.disconnect = g29_disconnect,
.id_table = g29_id_table,
};
module_usb_driver(g29_driver);

View File

@@ -45,7 +45,8 @@ Logitech G29 USB Protocol
- `0x02000000` - Red rotation clockwise - `0x02000000` - Red rotation clockwise
- `0x04000000` - Red rotation counterclockwise - `0x04000000` - Red rotation counterclockwise
- `0x08000000` - Return - `0x08000000` - Return
- `0xF0000000` - ? - `0x10000000` - PS3 Logo
- `0xE0000000` - ?
- `Rot`: Wheel rotation (little-endian). `0x0000` (leftmost) - `0xFFFF` (rightmost). - `Rot`: Wheel rotation (little-endian). `0x0000` (leftmost) - `0xFFFF` (rightmost).
- `Gas`: Gas pedal. `0xFF` (up, default) - `0x00` (down). - `Gas`: Gas pedal. `0xFF` (up, default) - `0x00` (down).
- `Brk`: Brake pedal. `0xFF` (up, default) - `0x00` (down). - `Brk`: Brake pedal. `0xFF` (up, default) - `0x00` (down).