The minibook_ec module gives Linux access to hardware in the MiniBook X that the stock kernel cannot reach. Once loaded, it provides:

• Touchpad and keyboard toggles -- enable or disable the touchpad and keyboard from the command line, useful for tablet mode scripts.
• Two thermal sensors -- a fast-reacting SoC temperature sensor and a charger temperature sensor, both visible as standard thermal zones. The patched thermald uses these to manage CPU power limits.
• Fan speed monitoring -- read current fan RPM and duty cycle. The fan is controlled by the EC firmware; this is read-only telemetry.
• Keyboard backlight control -- set brightness (0-255) and choose whether the backlight turns off automatically after inactivity. Desktop environments (GNOME, KDE) pick this up automatically.
• EC version -- read the embedded controller firmware version.
• BIOS unlock -- expose hidden BIOS menus on the next reboot into setup (one-shot, cleared after use).

Most of these integrate with standard Linux subsystems, so you rarely need to access them directly: thermal sensors show up in sensors (lm-sensors), the keyboard backlight works through your desktop environment's brightness controls and fan RPM appears in any hwmon monitoring tool. The sysfs paths documented below are there if you need them for scripts or debugging.

The module source lives in modules/minibook_ec/.

cd modules/minibook_ec
sudo make install
sudo make enable

This builds via DKMS against the running kernel, installs the module, and loads it on boot. To remove:

sudo make disable
sudo make uninstall

dmesg | grep minibook_ec

A successful load looks like:

minibook_ec minibook_ec: touchpad enabled, keyboard enabled, SoC registered, charger registered, fan registered, kbd_bl registered

Components that fail to initialize print a warning but do not prevent the rest of the module from loading.

# read current state
cat /sys/devices/platform/minibook_ec/touchpad_enabled
cat /sys/devices/platform/minibook_ec/keyboard_enabled

# disable touchpad (e.g., when using the device as a tablet)
echo 0 | sudo tee /sys/devices/platform/minibook_ec/touchpad_enabled

# re-enable
echo 1 | sudo tee /sys/devices/platform/minibook_ec/touchpad_enabled

keyboard_enabled works the same way. Setting it to 0 puts the device in slate mode (keyboard off), 1 restores laptop mode.

# set brightness (0 = off, 255 = max)
echo 128 | sudo tee /sys/class/leds/minibook::kbd_backlight/brightness

# keep backlight on permanently (disable auto-off timer)
echo 0 | sudo tee /sys/class/leds/minibook::kbd_backlight/auto_off_timer

# re-enable auto-off (backlight turns off after ~30s of inactivity)
echo 1 | sudo tee /sys/class/leds/minibook::kbd_backlight/auto_off_timer

# SoC temperature (millidegrees C, divide by 1000 for degrees)
cat /sys/class/thermal/thermal_zone*/temp   # find minibook_soc

# or more specifically:
grep -l minibook_soc /sys/class/thermal/thermal_zone*/type

cat /sys/class/hwmon/hwmon*/fan1_input   # RPM (find minibook_fan)
cat /sys/class/hwmon/hwmon*/pwm1         # duty cycle, 0-255

echo 1 | sudo tee /sys/devices/platform/minibook_ec/bios_unlock

Reboot into BIOS setup (press DEL during POST) to access hidden menus. The flag is cleared after one use.

cat /sys/devices/platform/minibook_ec/ec_version

Two thermal zones appear under /sys/class/thermal/:

Both report temperature in millidegrees C via the standard thermal_zone*/temp sysfs interface.

minibook_soc reads a single EC byte (register 0x70) that the firmware updates continuously. It is not one of the documented DPTF sensor registers (TSR1-5) -- it is an undocumented register that appears to track a thermistor physically adjacent to the SoC. It responds faster to load changes than the CPU die sensor (TCPU/coretemp), making it useful as an early warning for thermal management.

minibook_charger reads the IT5570E's built-in ADC. The raw 10-bit ADC value is converted to degrees C using a linear approximation calibrated against the NTC thermistor on this board. It only warms significantly when the charger is active under load.

Both zones require the I2EC interface to be available (charger) or the ACPI EC to be responsive (SoC). If either fails its probe-time sanity check, that zone is silently skipped.

The patched thermald uses these zones to install passive trip points. See thermald.md for details.

A read-only hwmon device (minibook_fan) appears under /sys/class/hwmon/:

The fan is controlled autonomously by the EC firmware -- there is no writable speed control from the OS. The EC uses its own internal thermal curve. These attributes are read-only telemetry.

RPM is calculated from the tachometer period: RPM = 1875000 / tach_count. A tach count of zero or 0xFFFF means the fan is stopped or unreadable, reported as 0 RPM.

A standard Linux LED device appears at /sys/class/leds/minibook::kbd_backlight/:

Setting brightness writes the PWM duty to the IT5570E hardware register and updates the EC firmware's setpoint so the two stay in sync.

auto_off_timer = 1 (default) lets the EC firmware turn off the backlight after ~30 seconds of keyboard inactivity. Keyboard activity re-arms the timer and restores the last brightness level.

auto_off_timer = 0 keeps the backlight on indefinitely regardless of keyboard activity. This matches the BIOS setting "Keyboard Backlight Mode = Always on."

Enable the poll_hw_changed module parameter to have GNOME/KDE/etc. track brightness changes triggered by the dedicated backlight toggle key or the auto-off timer:

echo 'options minibook_ec poll_hw_changed=1' \
  | sudo tee /etc/modprobe.d/minibook_ec.conf

This adds a brightness_hw_changed attribute under the LED node. UPower watches it via poll(2)/POLLPRI and re-broadcasts changes over D-Bus, which is what desktop environments listen to for "the keyboard backlight changed." Off by default because it requires a 250 ms in-kernel poll of the EC.

Four attributes appear under the platform device (/sys/devices/platform/minibook_ec/):

touchpad_enabled and keyboard_enabled take effect immediately. They are useful for tablet mode scripts that need to disable input when the screen is flipped.

bios_unlock is a one-shot flag. Writing 1 tells the EC to expose hidden BIOS menus on the next boot into setup. The flag is cleared by the BIOS after use.

All features except touchpad_enabled, keyboard_enabled, ec_version, bios_unlock and minibook_soc require the I2EC (Indirect EC) bus, which provides host access to the IT5570E's full 16-bit internal address space via PNPCFG Depth-2 I/O at port 0x4E/0x4F.

If another driver has claimed the 0x4E-0x4F I/O region, I2EC initialization fails and the charger thermal zone, fan hwmon and keyboard backlight are unavailable. The SoC thermal zone and sysfs attributes still work because they use the standard ACPI EC interface (ports 0x62/0x66).