Script to control battery charge and fn lock for Matebook X Pro. Requires vim (xxd), hexdump, dd, ec_sys module and bash.

hc.sh

#!/usr/bin/env bash

help() {
    cat <<EOF
Options:
- cc-disable
  Disable charging control
- cc-home
  Charging control to Home mode (40%-70%)
- cc-work
  Charging control to Work mode (70%-90%)
- cc-travel
  Charging control to Travel mode (95%)
- fn-keys
  Set default FN (LED off) to F-keys
- fn-functions
  Set default FN (LED off) to Functions
- ec
  Try to load ec_sys module and enable write support for it
  It is required for any other option to work
EOF
}

load_ec_write() {
    if modprobe ec_sys write_support=1; then
	return
    fi
    if echo Y > /sys/module/ec_sys/parameters/write_support; then
	return
    fi
    echo "Failed to load ec_sys or enable write_support."
    exit 1
}

battery_charge_control_disable() {
    # Load byte-register for charge control:
    CHARGE_CONTROL_BYTE_REGISTER=$(dd if=/sys/kernel/debug/ec/ec0/io bs=1 count=1 skip=67 conv=notrunc 2>/dev/null | hexdump -e '"%02x"')
    if [[ ${#CHARGE_CONTROL_BYTE_REGISTER} -lt 1 || ${#CHARGE_CONTROL_BYTE_REGISTER} -gt 2 ]]; then
	echo "Something went wrong when reading the register that holds the charge control status."
	# echo "Content: $CHARGE_CONTROL_BYTE_REGISTER. Length: ${#CHARGE_CONTROL_BYTE_REGISTER}."
	exit 1
    fi
    # We need to zero the second Most Significant Bit
    CCBR_VALUE=$(( 0x$CHARGE_CONTROL_BYTE_REGISTER & 2#10111111 ))
    # Write the new value back to the register
    CCBR_VALUE_HEX=$(printf "%02x" $CCBR_VALUE)
    echo -n "0000 $CCBR_VALUE_HEX" \
	| xxd -r \
	| dd of=/sys/kernel/debug/ec/ec0/io bs=1 count=1 seek=67 conv=notrunc   
    # Write 0s to threshold registers
    printf '\x00\x00' \
	| dd of=/sys/kernel/debug/ec/ec0/io bs=2 count=1 seek=114 conv=notrunc
}

battery_charge_control_enable() {
    LOW_THRESH=$1
    HIGH_THRESH=$2
    if [[ $LOW_THRESH -lt 40 ||
	      $LOW_THRESH -gt 95 ||
	      $HIGH_THRESH -lt 40 ||
	      $HIGH_THRESH -gt 95 ||
	      $LOW_THRESH -gt $HIGH_THRESH ]]; then
	cat <<EOF
Wrong thresholds. You should set:
40 <= low threshold <= 95
40 <= high threshold <= 95
low threshold <= high threshold
EOF
	exit 1
    fi
    # Set limits:
    LOW_THRESH_HEX=$(printf "%02x" $LOW_THRESH)
    HIGH_THRESH_HEX=$(printf "%02x" $HIGH_THRESH)
    echo "0000 $LOW_THRESH_HEX $HIGH_THRESH_HEX" \
	| xxd -r \
	| dd of=/sys/kernel/debug/ec/ec0/io bs=2 count=1 seek=114 conv=notrunc
    
    # Load byte-register for charge control:
    CHARGE_CONTROL_BYTE_REGISTER=$(dd if=/sys/kernel/debug/ec/ec0/io bs=1 count=1 skip=67 conv=notrunc | hexdump -e '"%02x"')
    if [[ ${#CHARGE_CONTROL_BYTE_REGISTER} -lt 1 || ${#CHARGE_CONTROL_BYTE_REGISTER} -gt 2 ]]; then
	echo "Something went wrong when reading the register that holds the charge control status."
	exit 1
    fi
    # We need to raise the second Most Significant Bit
    CCBR_VALUE=$(( 0x$CHARGE_CONTROL_BYTE_REGISTER | 2#01000000 ))
    # Write the new value back to the register
    CCBR_VALUE_HEX=$(printf "%02x" $CCBR_VALUE)
    echo "0000 $CCBR_VALUE_HEX" \
	| xxd -r \
	| dd of=/sys/kernel/debug/ec/ec0/io bs=1 count=1 seek=67 conv=notrunc   
}    

fn_lock() {
    BW_OP=""
    case $1 in
	keys)
	    BW_OP=" | 2#00000001"
	    ;;
	functions)
	    BW_OP=" & 2#11111110"
	    ;;
	*)
	    echo "Wrong toggle."
	    exit 1
	    ;;
    esac
    
    # Load 2 byte-registers for FN lock:
    FN_LOCK_BYTE_REGISTER_1=$(dd if=/sys/kernel/debug/ec/ec0/io bs=1 count=1 skip=230 conv=notrunc | hexdump -e '"%02x"')
    FN_LOCK_BYTE_REGISTER_2=$(dd if=/sys/kernel/debug/ec/ec0/io bs=1 count=1 skip=231 conv=notrunc | hexdump -e '"%02x"')
    if [[ ${#FN_LOCK_BYTE_REGISTER_1} -lt 1 || ${#FN_LOCK_BYTE_REGISTER_1} -gt 2 ]]; then
        echo "Something went wrong when reading the register #1 that holds the FN Lock status."
        exit 1
    fi
    if [[ ${#FN_LOCK_BYTE_REGISTER_2} -lt 1 || ${#FN_LOCK_BYTE_REGISTER_2} -gt 2 ]]; then
        echo "Something went wrong when reading the register #2 that holds the FN Lock status."
        exit 1
    fi

    # New values:
    REGISTER_1_HEX=$(printf "%02x" $(( 0x$FN_LOCK_BYTE_REGISTER_1 $BW_OP )) )
    REGISTER_2_HEX=$(printf "%02x" $(( 0x$FN_LOCK_BYTE_REGISTER_2 $BW_OP )) )
    echo "0000 $REGISTER_1_HEX $REGISTER_2_HEX" \
 	| xxd -r \
	| dd of=/sys/kernel/debug/ec/ec0/io bs=2 count=1 seek=115 conv=notrunc
}

case $1 in
    cc-disable)
	battery_charge_control_disable
	;;
    cc-home)
	battery_charge_control_enable 40 70
	;;
    cc-work)
	battery_charge_control_enable 70 90
	;;
    cc-travel)
	battery_charge_control_enable 95 95
	;;
    fn-keys)
	fn_lock keys
	;;
    fn-functions)
	fn_lock functions
	;;
    ec)
	load_ec_write
	;;
    *)
	help
	;;
esac

How do you reverse-engineer the sys_ec data?