zen-fan.sh

#!/bin/bash

# Copyright (c) 2023 Maxim Egorushkin. MIT License. See the full licence in file LICENSE.

set -eu

if((${TIMESTAMP:-1})); then
    function log { printf '%(%F %T)T %s\n' -1 "$1"; }
else
    function log { echo "$1"; }
fi

host_cfg=$PWD/zen-fan.d/host.$HOSTNAME.cfg

declare -i verbose
function v1off ((verbose<1))
function v2off ((verbose<2))
function v3off ((verbose<3))
function set_verbose {
    verbose=$(($1 < 0 ? 0 : $1 > 3 ? 3 : $1))
    v3off && set +x || set -x
}
set_verbose ${V:-1}

function raise {
    log "Error: $1" >&2
    exit 1
}

function apply {
    local a
    local -n args=$2
    for a in "${args[@]}"; do
        $1 $a
    done
}

function find_hwmon {
    local hwmon_name=$1
    local -n path=$1
    for hwmon in hwmon*; do
        read <$hwmon/name
        if [[ "$hwmon_name" == "$REPLY" ]]; then
            path=$hwmon
            log "$hwmon_name is $PWD/$path."
            return
        fi
    done
    raise "$hwmon_name not found in $PWD."
}

function read_temp_sensor {
    local -n temp=temp_$1
    local -n file=sensor_file_${1}
    read temp <${file}_input
    temp=$((temp / 1000))
}

function map_temp_to_rpm {
    local -n temp=temp_$1
    local -i temp_min=$2
    local -i temp_max=$3
    local -i rpm_min=$5
    local -i rpm_max=$6
    local -i rpm_step=$7
    local -i temp_pct=$(( ((temp < temp_min ? temp_min : (temp > temp_max ? temp_max : temp)) - temp_min) * 100 / (temp_max - temp_min) ))
    declare -gi rpm_fan_$4=$(( rpm_min + ((rpm_max - rpm_min) * temp_pct / 100) / rpm_step * rpm_step ))
}

function set_fan_rpm {
    local fan=$1
    echo $new_rpm >${fan}_target
}

function update_fan_group_rpm {
    local -n new_rpm=rpm_fan_$1
    local -n old_rpm=prev_rpm_fan_$1
    if((old_rpm != new_rpm)); then
        old_rpm=$new_rpm
        apply set_fan_rpm fans_$1
    fi
}

fan_groups=()
function create_fan_group {
    fan_groups+=($1)
    local name=$1 hwmon_name=$2
    declare -gi rpm_fan_$1 prev_rpm_fan_$1=0
    declare -g action_fan_$1
    local -n fans=fans_$1 path=$2
    shift 2
    fans=(${@/#/$path/})
    log "Fans $name $hwmon_name ${fans[*]}."
}

temp_sensors=()
function create_temp_sensor {
    temp_sensors+=($1)
    local name=$1 hwmon_name=$2
    local -n file=sensor_file_$1 path=$2
    declare -g temp_$1
    file=$path/$3
    log "$name temperature sensor is $hwmon_name $file."
}

sensors_to_fan_groups=()
function set_temp_to_rpm {
    sensors_to_fan_groups+=("$*")
}

function format_temp_sensor {
    local -n temp=temp_$1
    line+="$1 $temp°C, "
}

function format_fan {
    local fan=$1
    local cur_rpm
    read cur_rpm <${fan}_input
    line+="$fan ${cur_rpm}rpm, "
}

function format_fan_group {
    apply format_fan fans_$1
}

readonly action_names=('-' '' '+')
function format_fan_group_target {
    local -n new_rpm=rpm_fan_$1
    local -n old_rpm=prev_rpm_fan_$1
    local -i a=$(( (new_rpm > old_rpm) - (new_rpm < old_rpm) + 1 ))
    line+="$1 fans target ${new_rpm}rpm${action_names[$a]}, "
}

function log_status {
    local line=""
    apply format_temp_sensor temp_sensors
    apply format_fan_group fan_groups
    log "${line:0:-2}."
}

function log_target_rpm {
    local line=""
    apply format_temp_sensor temp_sensors
    apply format_fan_group_target fan_groups
    log "${line:0:-2}."
}

function update_fan_speeds {
    apply read_temp_sensor temp_sensors
    v2off || log_status
    apply map_temp_to_rpm sensors_to_fan_groups
    v1off || log_target_rpm
    apply update_fan_group_rpm fan_groups
}

sleep_sec=${SLEEP:-7}
function set_sleep_sec {
    sleep_sec=$1
}

function on_sigusr {
    set_verbose $((verbose + $1))
    log "$2 verbose=$verbose."
}

# Temperature sensors and fan controls files get re-opened on each read or write because bash cannot rewind open file descriptors.
# Keep hwmon directory open and resolved to speed up re-opening the files using relative paths.
cd /sys/class/hwmon

log "Config is $host_cfg."
source $host_cfg

# Environment overrides config.
set_verbose ${V:-$verbose}
set_sleep_sec ${SLEEP:-$sleep_sec}

function create_sleep2 {
    coproc sleep2_pipe { read; }
    function sleep2 { read -t$1 -u${sleep2_pipe[0]} || (($?>128)); }
}

trap "" SIGUSR1 SIGUSR2 SIGHUP

# cd ~/src/zen-fan/; TEST=1 sudo -E ./zen-fan.sh
if((${TEST:-0})); then
    function test_signals {
        set +e -x
        create_sleep2
        local pid=$1
        for((i=4;i--;)); do
            sleep2 2
            kill -USR1 $pid
        done
        for((i=4;i--;)); do
            sleep2 2
            kill -USR2 $pid
        done
        sleep2 2
        kill -USR1 $pid
        kill -HUP $pid
    }

    SLEEP=0.5
    N=40
    test_signals $$ &
fi

# Always log on start.
function update_and_log {
    local -i verbose=2
    update_fan_speeds
}
update_and_log

declare -i N=${N:--1}
if((N)); then
    create_sleep2
    trap 'on_sigusr +1 SIGUSR1' SIGUSR1
    trap 'on_sigusr -1 SIGUSR2' SIGUSR2
    trap 'log_status' SIGHUP

    readonly sleep_sec=${SLEEP:-7}
    trap 'log "Fan control loop terminated."' EXIT
    log "Fan control loop started. Adjust fans every $sleep_sec seconds for $N iterations."
    while((N -= N > 0)); do
        sleep2 $sleep_sec
        update_fan_speeds
    done
    :
fi