117 lines
2.4 KiB
Markdown
117 lines
2.4 KiB
Markdown
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Device Driver
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============
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This folder contains a minimal **out-of-tree** Linux kernel module that acts as a USB **boot-protocol mouse** driver.
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It supports:
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- Left and right buttons
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- Scroll wheel
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- Relative cursor motion (X/Y)
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Important notes
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---------------
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- This is an **educational** example. Real USB mice are normally handled by the kernel HID stack (e.g. `usbhid` / `hid-generic`).
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- This driver binds to HID **Boot Mouse** interfaces (class=HID, subclass=BOOT, protocol=MOUSE). Many mice work, but not all.
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- To use it on a running system you typically must **unbind** the existing driver from that USB interface first.
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Files
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-----
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- `usb_bootmouse.c` – kernel module (USB driver + input device)
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- `Makefile` – builds against your running kernel headers
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Build
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-----
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Install kernel headers/build deps (examples):
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- Debian/Ubuntu: `sudo apt-get install build-essential linux-headers-$(uname -r)`
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- Fedora: `sudo dnf install @development-tools kernel-devel-$(uname -r)`
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Then build:
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```bash
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cd Device-Driver
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make
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```
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Load
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----
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```bash
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sudo insmod usb_bootmouse.ko
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dmesg | tail -n 50
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```
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If you want to restrict binding to a specific device:
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```bash
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sudo insmod usb_bootmouse.ko match_vendor=0x046d match_product=0xc077
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```
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(Replace IDs with your mouse vendor/product from `lsusb`.)
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Bind it to your mouse (unbind/bind)
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---------------------------------
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1) Find the USB interface path.
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You can use `dmesg` when plugging the mouse in, or inspect:
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```bash
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ls -l /sys/bus/usb/devices/
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```
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Typical interface names look like `1-2:1.0` (bus-port:config.interface).
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2) Unbind the existing HID driver (commonly `usbhid`) from that interface:
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```bash
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DEVIF="1-2:1.0" # <- change this
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echo -n "$DEVIF" | sudo tee /sys/bus/usb/drivers/usbhid/unbind
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```
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3) Bind this module to the interface:
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```bash
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echo -n "$DEVIF" | sudo tee /sys/bus/usb/drivers/usb_bootmouse/bind
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```
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At this point, the driver should create an input device (via `evdev`).
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Test
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----
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List input devices and find the new one:
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```bash
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cat /proc/bus/input/devices
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```
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Or use `evtest`:
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```bash
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sudo apt-get install evtest # or your distro equivalent
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sudo evtest
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```
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You should see events:
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- `BTN_LEFT`, `BTN_RIGHT`
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- `REL_X`, `REL_Y`
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- `REL_WHEEL`
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Unload
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------
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```bash
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sudo rmmod usb_bootmouse
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```
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If you want the original HID driver back, bind it again:
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```bash
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echo -n "$DEVIF" | sudo tee /sys/bus/usb/drivers/usbhid/bind
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```
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