cpufreq: Don't remove sysfs link for policy->cpu

"cpufreq" directory in policy->cpu is never created using
sysfs_create_link(), but using kobject_init_and_add(). And so we
shouldn't call sysfs_remove_link() for policy->cpu().  sysfs stuff
for policy->cpu is automatically removed when we call kobject_put()
for dying policy.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Dirk Brandewie <dirk.brandewie@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Change-Id: Ie2f5ed66b2beb4104d4b0c1c4541bbb67499657f
zwliew: modify to use sys_devices
cpufreq: Remove unused HOTPLUG_CPU code

Because the sibling cpu of any online cpu is identified very early in
cpufreq_add_dev(), below code is never executed. And so can be removed.

Change-Id: I3106c2c77d03f31a10551a8738b9665d10613d4c
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Create a macro for unlock_policy_rwsem{read,write}

On the lines of macro: lock_policy_rwsem, we can create another macro for
unlock_policy_rwsem. Lets do it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Fix locking issues

cpufreq core uses two locks:
- cpufreq_driver_lock: General lock for driver and cpufreq_cpu_data array.
- cpu_policy_rwsemfix locking: per CPU reader-writer semaphore designed to cure
  all cpufreq/hotplug/workqueue/etc related lock issues.

These locks were not used properly and are placed against their principle
(present before their definition) at various places. This patch is an attempt to
fix their use.

Change-Id: I33fa3ba31de9e4bae9216114be04164cc3621f2c
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Retrieve current frequency from scaling drivers with internal governors

Scaling drivers that implement the cpufreq_driver.setpolicy() versus
the cpufreq_driver.target() interface do not set policy->cur.

Normally policy->cur is set during the call to cpufreq_driver.target()
when the frequnecy request is made by the governor.

If the scaling driver implements cpufreq_driver.setpolicy() and
cpufreq_driver.get() interfaces use cpufreq_driver.get() to retrieve
the current frequency.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Only call cpufreq_out_of_sync() for driver that implement cpufreq_driver.target()

Scaling drivers that implement cpufreq_driver.setpolicy() have
internal governors that do not signal changes via
cpufreq_notify_transition() so the frequncy in the policy will almost
certainly be different than the current frequncy.  Only call
cpufreq_out_of_sync() when the underlying driver implements
cpufreq_driver.target()

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Do not track governor name for scaling drivers with internal governors.

Scaling drivers that implement internal governors do not have governor
structures assocaited with them.  Only track the name of the governor
associated with the CPU if the driver does not implement
cpufreq_driver.setpolicy()

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cpufreq: Convert the cpufreq_driver_lock to a rwlock

This eliminates the contention I am seeing in __cpufreq_cpu_get.
It also nicely stages the lock to be replaced by the rcu.

Change-Id: If7cb3d860d4c4117000ef98754f8a99d11d1f455
Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>