EC read/write access through /sys/kernel/debug/ec

modulename: ec_sys.ko

Linux Kernel Configuration
└─> Power management and ACPI options
└─> ACPI (Advanced Configuration and Power Interface) Support
└─> EC read/write access through /sys/kernel/debug/ec

Say N to disable Embedded Controller /sys/kernel/debug interface

Be aware that using this interface can confuse your Embedded
Controller in a way that a normal reboot is not enough. You then
have to power off your system, and remove the laptop battery for
some seconds.
An Embedded Controller typically is available on laptops and reads
sensor values like battery state and temperature.
The kernel accesses the EC through ACPI parsed code provided by BIOS
tables. This option allows to access the EC directly without ACPI
code being involved.
Thus this option is a debug option that helps to write ACPI drivers
and can be used to identify ACPI code or EC firmware bugs.

source code: