cpufreq: stats: New sysfs attribute for clearing statistics

Allow CPUfreq statistics to be cleared by writing anything to
/sys/.../cpufreq/stats/reset.

Signed-off-by: Markus Mayer <mmayer@broadcom.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/Documentation/cpu-freq/cpufreq-stats.txt b/Documentation/cpu-freq/cpufreq-stats.txt
index 8d9773f..3c355f6 100644
--- a/Documentation/cpu-freq/cpufreq-stats.txt
+++ b/Documentation/cpu-freq/cpufreq-stats.txt
@@ -44,11 +44,17 @@
 total 0
 drwxr-xr-x  2 root root    0 May 14 16:06 .
 drwxr-xr-x  3 root root    0 May 14 15:58 ..
+--w-------  1 root root 4096 May 14 16:06 reset
 -r--r--r--  1 root root 4096 May 14 16:06 time_in_state
 -r--r--r--  1 root root 4096 May 14 16:06 total_trans
 -r--r--r--  1 root root 4096 May 14 16:06 trans_table
 --------------------------------------------------------------------------------
 
+-  reset
+Write-only attribute that can be used to reset the stat counters. This can be
+useful for evaluating system behaviour under different governors without the
+need for a reboot.
+
 -  time_in_state
 This gives the amount of time spent in each of the frequencies supported by
 this CPU. The cat output will have "<frequency> <time>" pair in each line, which