cpufreq: Add debugfs directory for cpufreq

This patch create debugfs root directory and child directory according to
the number of CPUs for CPUFreq as below debugfs directory path:
- /sys/kernel/debug/cpufreq/cpuX

If many CPUs share only one cpufreq policy, other CPUs(except for first CPU)
create a symbolic link for debugfs directory of CPU0.
- link: /sys/kernel/debug/cpufreq/cpu[1-(N-1)] -> /sys/kernel/debug/cpufreq/cpu0

And then cpufreq may need to create debugfs specific file below of debugfs
directory of cpufreq. (e.g., /sys/kernel/debug/cpufreq/cpu0/load_table)

Changes since v6:
- Use 'policy->related_cpus' instead of 'policy->cpus' when getting the number
  of CPUs included in the same package
- Get correct index of cpu_debugfs[] array according to cpu number
- Refactoring cpufreq_move_debugfs_dir() / cpufreq_create_debugfs_symlink()
- Use for_each_cpu() to support multi cluster instead of for_each_present_cpu()

Changes since v5:
- Refactoring patch v4
- Create again symbolic link of debugfs directory when first CPU dev is removed
  (In this case, many CPUs share only one cpufreq policy)

Change-Id: Ibd84118e6dd3b1e3bc624e1871d39425c99b1673
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 940f1fed44f..d8f40a14684 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -123,6 +123,8 @@ struct cpufreq_policy {
 	struct kobject		kobj;
 	struct completion	kobj_unregister;
 	int			transition_ongoing; /* Tracks transition status */
+
+	struct dentry		**cpu_debugfs;
 };
 
 #define CPUFREQ_ADJUST			(0)