Fix a variety of issues with sysfs_topology_read_file:
* The return value of sysfs_topology_read_file function was not properly
  being checked for failure.
* The function was reading int valued sysfs variables and then returning
  their value. So, even if a function was trying to check the return value
  of this function, a caller would not be able to tell an failure code apart
  from reading a negative value. This also conflicted with the comment on the
  function which said that a return value of 0 indicated success.
* The function was parsing int valued sysfs values with strtoul instead of
  strtol.
* The function was non-static even though it was only used in the
  file it was declared in.
Signed-off-by: NPalmer Cox <p@lmercox.com>
Signed-off-by: NThomas Renninger <trenn@suse.de>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Before, checking for offlined CPUs was done dirty and
it was checked whether topology parsing returned -1 values.
But this is a valid case on a Xen (and possibly other) kernels.

Do proper online/offline checking, also take CONFIG_HOTPLUG_CPU
option into account (no /sys/devices/../cpuX/online file).
Signed-off-by: NThomas Renninger <trenn@suse.de>
Signed-off-by: NDominik Brodowski <linux@dominikbrodowski.net>

Signed-off-by: NDominik Brodowski <linux@dominikbrodowski.net>

CPU power consumption vs performance tuning is no longer
limited to CPU frequency switching anymore: deep sleep states,
traditional dynamic frequency scaling and hidden turbo/boost
frequencies are tied close together and depend on each other.
The first two exist on different architectures like PPC, Itanium and
ARM, the latter (so far) only on X86. On X86 the APU (CPU+GPU) will
only run most efficiently if CPU and GPU has proper power management
in place.

Users and Developers want to have *one* tool to get an overview what
their system supports and to monitor and debug CPU power management
in detail. The tool should compile and work on as many architectures
as possible.

Once this tool stabilizes a bit, it is intended to replace the
Intel-specific tools in tools/power/x86
Signed-off-by: NDominik Brodowski <linux@dominikbrodowski.net>