getevent Tool Usage Guide

getevent is a command-line tool that monitors and displays real-time events from input devices such as touchscreens, keyboards, and mice. It provides detailed event data to help you debug input device drivers and applications.

I. Features

getevent provides the following core functions:

Mouse Event Monitoring: Tracks clicks, movements, and scroll wheel activity.
Multi-touch Capture: Captures data such as coordinates and timestamps for each touch point.
Keyboard Key Detection: Reports key codes and event types (e.g., press, release).
Automatic Device Discovery: Scans the /dev directory by default and monitors all detected input devices.
Specific Device Monitoring: Allows you to monitor one or more specific devices using command-line options.
Non-blocking I/O: Uses a non-blocking mode with a 500-millisecond timeout to avoid suspending the system while waiting for events.
Safe Resource Management: Ensures that resources are correctly released on exit (e.g., via Ctrl+C) to prevent memory or file descriptor leaks.

II. Build Configuration

To enable the getevent tool, you must set the following options in the openvela board-level configuration file:

# Enable the getevent tool
CONFIG_GRAPHICS_INPUT_GETEVENT=y

# (Optional) Enable detailed debug information for getevent
CONFIG_GRAPHICS_INPUT_GETEVENT_DETAIL_INFO=y

III. Usage Instructions

You can run getevent from the openvela command-line terminal (such as NSH).

Command Examples

Monitor all automatically detected devices:
```
getevent
```
Monitor a specific mouse device:
```
getevent -m /dev/mouse0
```
Monitor a specific touchscreen device:
```
getevent -t /dev/input0
```
Monitor a specific keyboard device:
```
getevent -k /dev/kbd0
```
Monitor multiple devices simultaneously:
```
getevent -m /dev/mouse0 -t /dev/input0
```

To stop monitoring, press Ctrl+C, and the program will terminate safely.

Parameter Descriptions

Parameter	Description
-m	Specifies the mouse device to monitor. Example: `/dev/mouse0`
-t	Specifies the touchscreen device to monitor. Example: `/dev/input0`
-k	Specifies the keyboard device to monitor. Example: `/dev/kbd0`

Output Example

When you run getevent, it first lists the devices being opened and then prints event data in real-time.

goldfish-armv7a-ap> getevent

[getevent]: opening /dev/input0
[getevent]: ioctl TSIOC_GETMAXPOINTS: 1
[getevent]: opening /dev/kbd0
[getevent]: opening /dev/mouse0

# Touchscreen event data
[getevent]: touch event: /dev/input0
[getevent]:    npoints : 1
[getevent]: Point      : 0
[getevent]:      flags : 11             # Touch event flags (e.g., press, move)
[getevent]:          x : 493
[getevent]:          y : 312
[getevent]:  timestamp : 31272800

# Keyboard event data
[getevent]: keyboard event: /dev/kbd0
[getevent]:          type : 0           # 0 represents KEY_DOWN (press), 1 represents KEY_UP (release)
[getevent]:          code : 57          # Key code, e.g., SPACE key

[getevent]: keyboard event: /dev/kbd0
[getevent]:          type : 1
[getevent]:          code : 57

# Mouse event data
[getevent]: mouse event: /dev/mouse0
[getevent]:    buttons : 00              # Bitmask of button states
[getevent]:          x : 14              # Relative displacement in the horizontal direction
[getevent]:          y : -16             # Relative displacement in the vertical direction

IV. Prerequisites

To successfully build and run getevent, your system must meet the following prerequisites:

Input Subsystem: You must enable the openvela input subsystem in your configuration. This subsystem provides the underlying drivers and event handling mechanisms required for getevent to process events. For details, see the Input Driver Development Guide.
System Log (Recommended): For easier debugging, we recommend enabling system log output in your kernel configuration. When CONFIG_GRAPHICS_INPUT_GETEVENT_DETAIL_INFO is enabled, getevent can print more detailed diagnostic messages.