Deepcool

An unofficial Linux kernel module Provides early boot support and sysfs interface for monitoring and controlling device display modes for Deepcool Digital USB HID devices (CPU coolers, AIOs, cases). The module runs directly in kernel space, providing early boot support and standard Linux interfaces for controlling Deepcool Digital USB HID devices.

Motive

This project exists solely because I hoped to replace the userspace daemon with a kernel module that is always loaded. Simply put, I don't need it to be an userspace daemon, and I am under the impression that using the Linux kernel APIs directly will yield be better performance, or at least less overhead.

deepcool-digital-linux is an userspace daemon that does a little more than this project, and is a more suitable replacement if you are not looking to taint your kernel with out-of-tree modules. Not that a "tainted kernel" is inherently bad, though. There are different usecases. See below for a better comparison between Deepcool (this module) and deepcool-digital-linux, the userspace daemon.

Features

The primary feature of Deepcool is that it supports early boot, or in other words, its functionality fully available as soon as you reach the kernel. Rest of the functionality is almost identical with little caveats.

• Real-time Monitoring: CPU temperature, usage, power, frequency
• Display Modes: Auto-cycling, CPU temp, CPU usage, CPU power, and more
• Sysfs Interface: Standard Linux interface for configuration
• Automatic Device Detection: Supports most Deepcool Digital product series
• Multiple Device Series Support:
  • AK Series (AK400 DIGITAL, AK500 DIGITAL, AK620 DIGITAL)
  • AK400 PRO, AK620 PRO
  • LS Series
  • AG Series
  • LQ Series
  • LD Series
  • LP Series
  • CH Series (Gen1, Gen2, CH510)

[!INFO] For device support, please refer to the device support matrix below

If you believe there is anything missing that belongs in a kernel module, please feel free to let me know. I'd be happy to discuss.

Usage

To use Deepcool, you must load it in your kernel. The installation steps may differ based on your distro, but most distros should be supported out of the box.

Requirements

• Linux kernel 5.10 or later
• Kernel headers for your running kernel
• Build essentials (gcc, make)
• Root/sudo access for installation

Kernel Configuration

The following kernel options must be enabled:

CONFIG_HID=y or m
CONFIG_HIDRAW=y or m
CONFIG_USB_HID=y or m
CONFIG_THERMAL=y
CONFIG_CPU_FREQ=y
CONFIG_CPUFREQ_STATS=y
CONFIG_SYSFS=y

Most of those features are enabled on most kernels, but is best to check before you build. zcat can be used to check the configuration for your current kernel configuration:

$ zcat /proc/config.gz | grep CONFIG_HID
# => CONFIG_HIDRAW=y

For Intel RAPL power monitoring:

CONFIG_POWERCAP=y
CONFIG_INTEL_RAPL=y or m

Building

Once you confirm that you meet the requirements, you may build the kernel module. To build, navigate to the cloned directory and run make.

$ make
#=> The module will be built as `deepcool.ko`.

Installation

Manual Installation

The Makefile provides a task to install Deepcool for Linux distributions using the DKMS framework. NixOS should refer to the section below.

# Build the module
make

# Install to system
sudo make dkms-install

# Load the module
sudo modprobe deepcool

Automatic Loading on Boot

Create a module configuration file:

sudo tee /etc/modules-load.d/deepcool_digital.conf <<EOF
deepcool
EOF

Once loaded, the module automatically detects connected Deepcool Digital devices and creates sysfs entries under /sys/bus/hid/drivers/deepcool_digital/.

Finding Your Device

# List all detected devices
ls /sys/bus/hid/drivers/deepcool_digital/

The device path will typically be something like:

/sys/bus/hid/drivers/deepcool_digital/0003:3633:0007.XXXX/

Replace 0003:3633:0007.XXXX with your actual device path in the examples below.

Sysfs Attributes

This module uses sysfs to interact with the module. You may find configuration attributes below.

Configuration Attributes (Read/Write)

mode - Display mode

# View current mode
cat mode

# Set mode
echo "cpu_temp" > mode

# Available modes:
# - auto          (cycle between supported metrics)
# - cpu_temp      (CPU temperature)
# - cpu_usage     (CPU usage percentage)
# - cpu_power     (CPU power consumption)
# - cpu_freq      (CPU frequency)
# - cpu_fan       (CPU fan speed, if supported)
# - gpu_temp      (GPU temperature, if supported)
# - gpu_usage     (GPU usage, if supported)
# - gpu_power     (GPU power, if supported)

update_interval - Update interval in milliseconds (100-2000)

# View current interval
cat update_interval

# Set to 500ms
echo 500 > update_interval

fahrenheit - Temperature unit (0=Celsius, 1=Fahrenheit)

# Use Fahrenheit
echo 1 > fahrenheit

# Use Celsius
echo 0 > fahrenheit

alarm - Temperature alarm (0=off, 1=on)

# Enable alarm
echo 1 > alarm

# Disable alarm
echo 0 > alarm

Sensor Attributes (Read-Only)

cpu_temp - CPU temperature (°C or °F based on fahrenheit setting)

cat cpu_temp

cpu_usage - CPU usage percentage (0-100)

cat cpu_usage

cpu_power - CPU power consumption (Watts)

cat cpu_power

cpu_freq - CPU frequency (MHz)

cat cpu_freq

Examples

Set CPU temperature display with Fahrenheit

echo "cpu_temp" > /sys/bus/hid/drivers/deepcool_digital/0003:3633:0007.XXXX/mode
echo 1 > fahrenheit
echo 1 > alarm

Auto-cycle between metrics at 1-second intervals

echo "auto" > /sys/bus/hid/drivers/deepcool_digital/0003:3633:0007.XXXX/mode
echo 1000 > /sys/bus/hid/drivers/deepcool_digital/0003:3633:0007.XXXX/update_interval

Monitor CPU power consumption

echo "cpu_power" > /sys/bus/hid/drivers/deepcool_digital/0003:3633:0007.XXXX/mode

Create a simple monitoring script

#!/usr/bin/env bash
DEVICE="/sys/bus/hid/drivers/deepcool_digital/0003:3633:0007.XXXX"

while true; do
    echo "CPU Temp:  $(cat $DEVICE/cpu_temp)°C"
    echo "CPU Usage: $(cat $DEVICE/cpu_usage)%"
    echo "CPU Power: $(cat $DEVICE/cpu_power)W"
    echo "CPU Freq:  $(cat $DEVICE/cpu_freq)MHz"
    echo "---"
    sleep 1
done

Device Support Matrix

Device Series	Auto Mode	Alarm	Fahrenheit	Secondary Display	Rotation
AK Series	✓	✓	✓	✗	✗
AK400 PRO	✓	HW	✓	✗	✗
AK620 PRO	✓	HW	✓	✗	✗
LS Series	✓	✓	✓	✗	✗
AG Series	✓	✓	✗	✗	✗
LP Series	✓	✗	✓	✓	✓
LQ Series	✓	✓	✓	✗	✗
CH Series	✓	varies	varies	varies	✗

Legend:

Supported	Not Supported	Hardware-Controlled (Fixed thresholds)
✓	✗	HW

How It Works

Initialization

1. Module loads and registers HID driver
2. Kernel calls probe() when device is detected
3. Driver identifies device series and capabilities
4. Sysfs attributes are created
5. Work queue is scheduled for periodic updates

Runtime Operation

Timer fires (every update_interval ms)
    ↓
Work queue handler executes
    ↓
Read CPU sensors:
  * Temperature from thermal subsystem
  * Usage from kernel CPU statistics
  * Frequency from CPUFreq
  * Power from Intel RAPL
    ↓
Build device-specific packet
    ↓
Send HID output report over USB
    ↓
Display updates
    ↓
Reschedule work queue

User Interaction

User writes to sysfs attribute
    ↓
Kernel calls store() handler
    ↓
Validate input
    ↓
Update device configuration
    ↓
Next work cycle uses new configuration

Contributing

Contributions are always welcome! When submitting patches, please try to follow the several recommendations:

• Tabs and 8 character indentations are heretical. A cardinal sin. Please don't use those.
• Testing on your own hardware is recommended, but not a hard-requirement
• If there is device-specific behaviour (or non-behaviour), please document it!
• Include dmesg output for new devices

Refer to BUILD.md for additional notes on working with and building Deepcool.

License

GPL-2.0-only

Attributions

There are a few projects that I would like to give credit to. Namely I'd like to thank the deepcool-digital-linux project for the inspiration and the device data. This project would be incredibly annoying to do without the efforts of Nortank12. Please make sure to give them some love!

I'd like to extend my thanks to the zenpower project that provided insight into developing Linux kernel modules, and the DKMS installation tasks. Thank you :)

See Also

• deepcool-digital-linux: an userspace daemon providing similar functionality, with better GPU support.
• Linux HID documentation: Documentation/hid/ in kernel source
• Sysfs documentation: Documentation/filesystems/sysfs.txt