cpupower: add a systemd service to run cpupower

One of the most typical use cases of the 'cpupower' utility works as
follows: run 'cpupower' at boot with the desired command-line options
and then forget about it.

Add a systemd service (disabled by default) that automates this use
case (for environments where the initialization system is 'systemd'),
by running 'cpupower' at boot with the settings read from a default
configuration file.

The systemd service, the associated support script and the
corresponding default configuration file are derived from what is
provided by the Arch Linux package (under "GPL-2.0-or-later" terms),
modernized and enhanced in various ways (the script has also been
checked with 'shellcheck').

Link: https://gitlab.archlinux.org/archlinux/packaging/packages/linux-tools/-/tree/dd2e2a311e05413d0d87a0346ffce8c7e98d6d2b

Signed-off-by: Francesco Poli (wintermute) <[e-mail]>
Reviewed-by: John B. Wyatt IV <[e-mail]>
Reviewed-by: John B. Wyatt IV <[e-mail]>
Tested-by: John B. Wyatt IV <[e-mail]>
Tested-by: John B. Wyatt IV <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/power/cpupower/Makefile

···
 # Makefile for cpupower
 #
 # Copyright (C) 2005,2006 Dominik Brodowski <[e-mail]>
+# Copyright (C) 2025      Francesco Poli <[e-mail]>
 #
 # Based largely on the Makefile for udev by:
 #
···
 sbindir ?=	/usr/sbin
 mandir ?=	/usr/man
 libdir ?=	/usr/lib
+libexecdir ?=	/usr/libexec
 includedir ?=	/usr/include
 localedir ?=	/usr/share/locale
 docdir ?=       /usr/share/doc/packages/cpupower
···
 INSTALL = /usr/bin/install -c
 INSTALL_PROGRAM = ${INSTALL}
 INSTALL_DATA  = ${INSTALL} -m 644
+SETPERM_DATA  = chmod 644
 #bash completion scripts get sourced and so they should be rw only.
 INSTALL_SCRIPT = ${INSTALL} -m 644
 
···
 	$(INSTALL_PROGRAM) $(OUTPUT)cpupower $(DESTDIR)${bindir}
 	$(INSTALL) -d $(DESTDIR)${bash_completion_dir}
 	$(INSTALL_SCRIPT) cpupower-completion.sh '$(DESTDIR)${bash_completion_dir}/cpupower'
+	$(INSTALL) -d $(DESTDIR)${confdir}default
+	$(INSTALL_DATA) cpupower.default '$(DESTDIR)${confdir}default/cpupower'
+	$(INSTALL) -d $(DESTDIR)${libexecdir}
+	$(INSTALL_PROGRAM) cpupower.sh '$(DESTDIR)${libexecdir}/cpupower'
+	$(INSTALL) -d $(DESTDIR)${libdir}/systemd/system
+	sed 's|___CDIR___|$(DESTDIR)${confdir}|; s|___LDIR___|$(DESTDIR)${libexecdir}|' cpupower.service.in > '$(DESTDIR)${libdir}/systemd/system/cpupower.service'
+	$(SETPERM_DATA) '$(DESTDIR)${libdir}/systemd/system/cpupower.service'
+	if test -d /run/systemd/system; then systemctl daemon-reload; fi
 
 install-man:
 	$(INSTALL_DATA) -D man/cpupower.1 $(DESTDIR)${mandir}/man1/cpupower.1
···
 	- rm -f $(DESTDIR)${includedir}/cpufreq.h
 	- rm -f $(DESTDIR)${includedir}/cpuidle.h
 	- rm -f $(DESTDIR)${bindir}/utils/cpupower
+	- rm -f $(DESTDIR)${confdir}default/cpupower
+	- rm -f $(DESTDIR)${libexecdir}/cpupower
+	- rm -f $(DESTDIR)${libdir}/systemd/system/cpupower.service
 	- rm -f $(DESTDIR)${mandir}/man1/cpupower.1
 	- rm -f $(DESTDIR)${mandir}/man1/cpupower-frequency-set.1
 	- rm -f $(DESTDIR)${mandir}/man1/cpupower-frequency-info.1
···
 	- for HLANG in $(LANGUAGES); do \
 		rm -f $(DESTDIR)${localedir}/$$HLANG/LC_MESSAGES/cpupower.mo; \
 	  done;
+	- if test -d /run/systemd/system; then systemctl daemon-reload; fi
 
 help:
 	@echo  'Building targets:'

tools/power/cpupower/README

···
 -----------------------------------------------------------------------
 | man pages              | /usr/man                                   |
 -----------------------------------------------------------------------
+| systemd service        | /usr/lib                                   |
+-----------------------------------------------------------------------
+| systemd support script | /usr/libexec                               |
+-----------------------------------------------------------------------
 
 To put it in other words it makes build results available system-wide,
 enabling any user to simply start using it without any additional steps
···
 | cpufreq-bench_plot.sh  | ${DESTDIR}/usr/bin                         |
 -----------------------------------------------------------------------
 | man pages              | ${DESTDIR}/usr/man                         |
+-----------------------------------------------------------------------
+| systemd service        | ${DESTDIR}/usr/lib                         |
+-----------------------------------------------------------------------
+| systemd support script | ${DESTDIR}/usr/libexec                     |
 -----------------------------------------------------------------------
 
 If you look at the table for the default 'make' output dirs you will
···
 The issue is that binary cannot find the 'libcpupower' library. So, we
 shall point to the lib dir:
 sudo LD_LIBRARY_PATH=lib64/ ./bin/cpupower
+
+systemd service
+---------------
+
+A systemd service is also provided to run the cpupower utility at boot with
+settings read from a configuration file. In order to enable this systemd
+service, edit '${DESTDIR}/etc/default/cpupower' (uncommenting at least one of
+the options, depending on your preferences) and then issue the following
+command:
+
+$ sudo systemctl enable --now cpupower.service
 
 
 THANKS

tools/power/cpupower/cpupower.default

···
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (C) 2012, Sébastien Luttringer
+# Copyright (C) 2024-2025, Francesco Poli <[e-mail]>
+
+# Default file for linux-cpupower
+
+# --- CPU clock frequency ---
+
+# Define CPU governor
+# Valid governors: ondemand, performance, powersave, conservative, userspace
+#GOVERNOR='ondemand'
+
+# Limit frequency range
+# Valid suffixes: Hz, kHz (default), MHz, GHz, THz
+#MIN_FREQ="2.25GHz"
+#MAX_FREQ="3GHz"
+
+# Specific frequency to be set.
+# Requires userspace governor to be available.
+# If this option is set, all the previous frequency options are ignored
+#FREQ=
+
+# --- CPU policy ---
+
+# Sets a register on supported Intel processore which allows software to convey
+# its policy for the relative importance of performance versus energy savings to
+# the processor. See man CPUPOWER-SET(1) for additional details
+#PERF_BIAS=

tools/power/cpupower/cpupower.service.in

···
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (C) 2012-2020, Sébastien Luttringer
+# Copyright (C) 2024, Francesco Poli <[e-mail]>
+
+[Unit]
+Description=Apply cpupower configuration
+ConditionVirtualization=!container
+
+[Service]
+Type=oneshot
+EnvironmentFile=-___CDIR___default/cpupower
+ExecStart=___LDIR___/cpupower
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target

tools/power/cpupower/cpupower.sh

···
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (C) 2012, Sébastien Luttringer
+# Copyright (C) 2024, Francesco Poli <[e-mail]>
+
+ESTATUS=0
+
+# apply CPU clock frequency options
+if test -n "$FREQ"
+then
+    cpupower frequency-set -f "$FREQ" > /dev/null || ESTATUS=1
+elif test -n "${GOVERNOR}${MIN_FREQ}${MAX_FREQ}"
+then
+    cpupower frequency-set \
+      ${GOVERNOR:+ -g "$GOVERNOR"} \
+      ${MIN_FREQ:+ -d "$MIN_FREQ"} ${MAX_FREQ:+ -u "$MAX_FREQ"} \
+      > /dev/null || ESTATUS=1
+fi
+
+# apply CPU policy options
+if test -n "$PERF_BIAS"
+then
+    cpupower set -b "$PERF_BIAS" > /dev/null || ESTATUS=1
+fi
+
+exit $ESTATUS