For low-level drivers, gestures can be delegated to userspace (e.g., libinput). Touchpad drivers must support suspend/resume and idle power reduction.
static int tp_probe(struct hid_device *hdev, const struct hid_device_id *id) hid compliant touchpad driver
input_mt_sync_frame(input); input_sync(input); return 0; The driver optionally performs basic gesture detection (two-finger scroll, pinch) before passing events up. For low-level drivers, gestures can be delegated to
// Send sleep command to touchpad over HID u8 sleep_cmd[] = 0x00, 0x02; // Vendor-specific sleep opcode hid_hw_raw_request(hdev, 0x02, sleep_cmd, 2, HID_FEATURE_REPORT, HID_REQ_SET_REPORT); return 0; // Send sleep command to touchpad over HID
Abstract —Touchpads have become ubiquitous input devices for portable computing systems. However, operating system compatibility, gesture recognition, and power efficiency remain challenges for custom touchpad hardware. This paper presents the design and implementation of a HID-compliant touchpad driver that bridges custom touchpad hardware with standard operating system input subsystems. We detail the USB HID descriptor structure, multi-touch protocol (MT Protocol B), interrupt handling, gesture interpretation, and power management. The driver is implemented for a Linux kernel module and validated against Windows 11 and macOS evdev compatibility layers. Experimental results show sub-10ms latency, support for up to 5 simultaneous touches, and average power consumption of 8.5mW.
Touchpad Sensor → Microcontroller (Firmware) → USB/I2C → HID Driver → Input Subsystem → User Apps A valid HID descriptor defines the format of input reports. Below is a minimal multi-touch touchpad descriptor (simplified for clarity):