*************************************************************************
Call hierarchy of __cpufreq_driver_target in drivers/cpufreq/cpufreq.c.
*************************************************************************
NOTE:
-----
* [C] : hotcpu callback path.

* the representation
A
|
|- B
   |
   |- C

means function C calls function B which calls function A.
*************************************************************************

__cpufreq_driver_target.
|
|- cpufreq_driver_target
|  |
|  |- cpufreq_cpu_callback[C]
|
|- dbs_check_cpu(conservative)
|  |
|  |- do_dbs_timer(conservative)
|
|- dbs_check_cpu(ondemand)
|  |
|  |- do_dbs_timer(ondemand) 
|
|- do_dbs_timer (ondemand)
|
|- cpufreq_set
|  |
|  |- store_speed(userspace)
|
|- __cpufreq_governor(GOV_LIMITS)
   |
   |- __cpufreq_set_policy
      |
      |- store_one
      |
      |- store_scaling_governor
      |
      |- cpufreq_set_policy
      |  |
      |  |- acpi_processor_write_performance
      |  |
      |  |- cpufreq_add_dev
      |     |
      |     |- cpufreq_cpu_callback [C]
      |
      |- cpufreq_update_policy
         |
         |- handle_update
	 |
	 |- cpufreq_stat_cpu_callback [C]