#!/usr/bin/env bash
# A fake /sys for the CPU guard, so heat can be simulated without heat. Point the
# program at it with [Thermal] sysfs_root = <root> (config.ini or hardware.ini)
# and change the temperature while it runs.
#
#   tools/thermal-sim/fake-temp.sh <root> init          # build the tree (4 cores, 3.6 GHz, 70 C)
#   tools/thermal-sim/fake-temp.sh <root> <C>           # set the CPU temperature
#   tools/thermal-sim/fake-temp.sh <root> <C> throttle  # ...and count one throttle event
#   tools/thermal-sim/fake-temp.sh <root> clock <MHz>   # set every core's clock
#   tools/thermal-sim/fake-temp.sh <root> ramp <C> <C> <step> <secs-per-step>
#                                                       # walk the temperature, throttling
#                                                       # at 90 C and above
#
# The tree has no proc/stat, so the program reads the real /proc/stat: how busy
# the CPU is stays real (raise it with heat-load.sh).
set -euo pipefail

usage() { sed -n '2,15p' "$0" >&2; exit 2; }
[[ $# -ge 2 ]] || usage
root=$1; shift
cpu=$root/sys/devices/system/cpu
zone=$root/sys/class/thermal/thermal_zone0

init() {
    rm -f "$root/proc/stat"   # an older tree's frozen copy would hide the real one
    mkdir -p "$zone"
    echo x86_pkg_temp > "$zone/type"
    echo 70000 > "$zone/temp"
    for c in 0 1 2 3; do
        mkdir -p "$cpu/cpu$c/cpufreq" "$cpu/cpu$c/thermal_throttle"
        echo 2800000 > "$cpu/cpu$c/cpufreq/scaling_cur_freq"
        echo 3600000 > "$cpu/cpu$c/cpufreq/cpuinfo_max_freq"
        echo 3600000 > "$cpu/cpu$c/cpufreq/scaling_max_freq"
        echo 0 > "$cpu/cpu$c/thermal_throttle/package_throttle_count"
        echo 0 > "$cpu/cpu$c/thermal_throttle/core_throttle_count"
    done
    echo "fake tree ready at $root: 70 C, 2.8 of 3.6 GHz"
}

set_temp() {   # <C> [throttle]
    echo $(( $1 * 1000 )) > "$zone/temp"
    if [[ ${2:-} == throttle ]]; then
        f=$cpu/cpu0/thermal_throttle/package_throttle_count
        echo $(( $(cat "$f") + 1 )) > "$f"
    fi
}

[[ $1 == init ]] && { init; exit 0; }
[[ -d $zone ]] || { echo "$0: no tree at $root - run '$0 $root init' first" >&2; exit 1; }

case $1 in
    clock)
        [[ $# -eq 2 ]] || usage
        for c in "$cpu"/cpu[0-9]*; do echo $(( $2 * 1000 )) > "$c/cpufreq/scaling_cur_freq"; done
        echo "clock $2 MHz" ;;
    ramp)
        [[ $# -eq 5 ]] || usage
        from=$2 to=$3 step=$4 secs=$5
        (( from > to )) && step=$(( -step ))
        t=$from
        while :; do
            echo "$(date +%T) $t C"
            # Hold the step; at 90 C and up the CPU throttles, one counted
            # event every 2 s.
            for (( i = 0; i < secs; i += 2 )); do
                if (( t >= 90 )); then set_temp "$t" throttle; else set_temp "$t"; fi
                sleep 2
            done
            (( t == to )) && break
            t=$(( t + step ))
            (( (step > 0 && t > to) || (step < 0 && t < to) )) && t=$to
        done ;;
    *)
        [[ $1 =~ ^[0-9]+$ ]] || usage
        set_temp "$1" "${2:-}"
        echo "CPU $1 C${2:+, one throttle event}" ;;
esac