cpupower: Add is_valid_path API

Add is_valid_path API to check whether the sysfs file is present or not.

Suggested-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Wyes Karny <wyes.karny@amd.com>
Tested-by: Perry Yuan <Perry.Yuan@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/power/cpupower: Read energy_perf_bias from sysfs

... instead of poking at the MSR. For that, move the accessor functions
to misc.c and add a sysfs-writing function too.

There should be no functional changes resulting from this.

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Cc: Thomas Renninger <trenn@suse.com>
Link: https://lkml.kernel.org/r/20201029190259.3476-2-bp@alien8.de

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 166

Based on 1 normalized pattern(s):

licensed under the terms of the gnu gpl license version 2

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 62 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.929121379@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/power/cpupower: fix compilation with STATIC=true

Rename duplicate sysfs_read_file into cpupower_read_sysfs and fix linking.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Thomas Renninger <trenn@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

cpupower: Add cpuidle parts into library

This more or less is a renaming and moving of functions and should not
introduce any functional change.

cpupower was built from cpufrequtils (which had a C library providing easy
access to cpu frequency platform info). In the meantime it got enhanced
by quite some neat cpuidle userspace tools.

Now the cpu idle functions have been separated and added to the cpupower.so
library.
So beside an already existing public header file:
cpufreq.h
cpupower now also exports these cpu idle functions in:
cpuidle.h

Here again pasted for better review of the interfaces:

======================================
int cpuidle_is_state_disabled(unsigned int cpu,
unsigned int idlestate);
int cpuidle_state_disable(unsigned int cpu, unsigned int idlestate,
unsigned int disable);
unsigned long cpuidle_state_latency(unsigned int cpu,
unsigned int idlestate);
unsigned long cpuidle_state_usage(unsigned int cpu,
unsigned int idlestate);
unsigned long long cpuidle_state_time(unsigned int cpu,
unsigned int idlestate);
char *cpuidle_state_name(unsigned int cpu,
unsigned int idlestate);
char *cpuidle_state_desc(unsigned int cpu,
unsigned int idlestate);
unsigned int cpuidle_state_count(unsigned int cpu);

char *cpuidle_get_governor(void);
char *cpuidle_get_driver(void);

======================================

Signed-off-by: Thomas Renninger <trenn@suse.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>