Minimal cross-platform fan speed control — CLI, TUI dashboard, and GUI for Linux & Windows. Lenovo Legion fan curve support via WMI.

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# Install Rust (if not already installed)
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

# Clone and build
git clone https://github.com/pjt222/fancontrol.git
cd fancontrol
cargo build --release

# Run (Linux — may need sudo for PWM write access)
sudo ./target/release/fancontrol list

# Run (Windows — needs Administrator for WMI access)
.\target\release\fancontrol.exe list

fancontrol list                    # Show all detected fans
fancontrol get fan0                # Get fan0 speed in RPM
fancontrol set fan0 128            # Set fan0 to 50% duty cycle
fancontrol monitor                 # Live fan monitor (Ctrl+C to stop)
fancontrol table                   # Display EC fan curve data
fancontrol tui                     # Interactive terminal dashboard
fancontrol gui                     # Graphical interface
fancontrol list --json             # Machine-readable JSON output

# Custom fan curve with config persistence (Lenovo)
fancontrol set-curve --fan-id 0 --sensor-id 3 \
  --steps "0,0,0,1,2,4,6,7,8,10" --save

• CLI with subcommands: list, get, set, monitor, table, set-curve, tui, gui
• JSON output (--json) for list, get, and table commands
• TUI dashboard (ratatui) with viridis color scheme, real-time fan/temp display, interactive curve editor, and keyboard-driven controls
• GUI (egui/eframe) with per-fan sliders, curve editor, SmartFanMode display, and real-time polling
• Config persistence — save custom curves to fancontrol.json with --save; auto-reapplied on startup
• Custom fan curves for Lenovo Legion via Fan_Set_Table with safety validation
• Linux: sysfs/hwmon backend — reads fan*_input, writes pwm*
• Windows: WMI backend — generic Win32_Fan (read-only) with Lenovo Legion vendor support
• Lenovo Legion: full speed toggle, SmartFanMode (Quiet/Balanced/Performance/Custom), EC fan curve display and editing

Generated with putior from // put annotations in source.

flowchart TD
    cli_def["CLI Definition - clap<br/>cli.rs"]
    fan_structs[("Fan/FanCurve Data Structs<br/>fan.rs")]
    gui_init["Launch GUI + Worker Thread<br/>gui.rs"]
    worker_loop["Worker Poll Loop 1.5s<br/>gui.rs"]
    worker_refresh["Re-apply held_pwm + Discover<br/>gui.rs"]
    ui_render["Render Fan Cards<br/>gui.rs"]
    ui_set_pwm["User Sets PWM<br/>gui.rs"]
    cli_parse["Parse CLI Arguments<br/>main.rs"]
    setup_logging["Setup File Logger<br/>main.rs"]
    create_ctrl["Create Platform Controller<br/>main.rs"]
    dispatch["Dispatch CLI Command<br/>main.rs"]
    lenovo_discover["Lenovo Discovery - PowerShell<br/>lenovo.rs"]
    lenovo_ps(["PowerShell WMI Subprocess<br/>lenovo.rs"])
    lenovo_parse["Parse TABLE/FAN/FULLSPEED<br/>lenovo.rs"]
    lenovo_set["Set Fan Speed - WMI<br/>lenovo.rs"]
    linux_discover["Scan sysfs/hwmon<br/>linux.rs"]
    linux_read["Read Fan Speed<br/>linux.rs"]
    linux_write["Write PWM Value<br/>linux.rs"]
    platform_select{"Platform Detection<br/>mod.rs"}
    win_wmi["Query Win32_Fan - WMI<br/>windows.rs"]

    %% Connections
    gui_init --> worker_loop
    ui_set_pwm --> worker_loop
    ui_set_pwm --> worker_refresh
    gui_init --> ui_render
    worker_loop --> ui_render
    cli_def --> create_ctrl
    cli_parse --> create_ctrl
    cli_def --> dispatch
    cli_parse --> dispatch
    create_ctrl --> dispatch
    platform_select --> dispatch
    lenovo_ps --> lenovo_parse

    %% Styling
    classDef decisionStyle fill:#fef3c7,stroke:#d97706,stroke-width:2px,color:#92400e
    class platform_select decisionStyle

Requires Rust.

cargo build --release

rustup target add x86_64-pc-windows-gnu
sudo apt-get install mingw-w64
cargo build --release --target x86_64-pc-windows-gnu

The binary will be at target/x86_64-pc-windows-gnu/release/fancontrol.exe.

fancontrol list              # Human-readable table
fancontrol list --json       # JSON output

fancontrol get <FAN_ID>
fancontrol get fan0 --json   # {"fan_id":"fan0","rpm":2100}

fancontrol set <FAN_ID> <PWM>   # PWM 0-255

fancontrol monitor [-i <SECONDS>]   # Default: 1s refresh

fancontrol table                 # All curves
fancontrol table --fan-id 0      # CPU fan only
fancontrol table --json          # JSON output

# 10 comma-separated speed step indices (0-10 scale)
fancontrol set-curve --fan-id 0 --sensor-id 3 --steps "0,0,0,1,2,4,6,7,8,10"

# Save to config for automatic re-application on startup
fancontrol set-curve --fan-id 0 --sensor-id 3 --steps "0,0,0,1,2,4,6,7,8,10" --save

Steps index into the hardware's FanSpeeds array from LENOVO_FAN_TABLE_DATA. Safety validation enforces non-decreasing values and minimum thresholds at high temperatures. Requires Custom SmartFanMode (auto-switched).

fancontrol tui

Viridis-themed terminal dashboard with real-time fan speeds, temperature readings, and an interactive curve editor.

Fan select mode: j/k select fan, Tab/Shift+Tab cycle sensor, Enter edit curve, f toggle full speed, a apply curve, s save to config, r reset to BIOS, q quit.

Curve edit mode: j/k select step, h/l adjust value +/-1, Enter/a apply and exit, s apply and save, Esc revert changes.

fancontrol gui

Use -v flags to increase log verbosity (written to fancontrol.log):

fancontrol -v list       # Info level
fancontrol -vv list      # Debug level
fancontrol -vvv list     # Trace level

Default log level is Warn.

Linux: Scans /sys/class/hwmon/ for fan inputs and PWM files. Requires write permissions on pwm* files (run as root or configure udev rules).

Windows (generic): Queries Win32_Fan WMI class. Most hardware does not expose fans through this class — results are often empty.

Windows (Lenovo Legion): Detected automatically via Win32_ComputerSystem.Manufacturer. Uses LENOVO_FAN_METHOD and LENOVO_FAN_TABLE_DATA in the root\WMI namespace via PowerShell subprocess. Requires administrator privileges.

• Linux backend requires root or appropriate permissions for PWM write access
• Windows generic Win32_Fan is read-only — vendor-specific WMI is needed for control
• Lenovo WMI Fan_Get_Table and Fan_Get_MaxSpeed return empty data on some firmware
• Fan_Set_Table call succeeds but behavioral effect is unverified at idle temperatures (needs load test above 58°C)
• Custom curves are volatile at the hardware level (lost on reboot, sleep/wake, or Fn+Q power mode change) — use --save or the TUI s key to persist curves for automatic re-application on startup

• LenovoLegionToolkit — community knowledge of Lenovo WMI fan control classes and methods
• FanControl by Rem0o — Windows fan monitoring and control
• lm-sensors — Linux hwmon sysfs conventions for fan speed and PWM control

MIT