[CPUFREQ] Introduce global, not per core: /sys/devices/system/cpu/cpufreq

Currently everything in the cpufreq layer is per core based.
This does not reflect reality, for example ondemand on conservative
governors have global sysfs variables.

Introduce a global cpufreq directory and add the kobject to the governor
struct, so that governors can easily access it.
The directory is initialized in the cpufreq_core_init initcall and thus will
always be created if cpufreq is compiled in, even if no cpufreq driver is
active later.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>

drivers/cpufreq/cpufreq.c

@@ -686,6 +686,9 @@ static struct attribute *default_attrs[] = {
 	NULL
 };
 
+struct kobject *cpufreq_global_kobject;
+EXPORT_SYMBOL(cpufreq_global_kobject);
+
 #define to_policy(k) container_of(k, struct cpufreq_policy, kobj)
 #define to_attr(a) container_of(a, struct freq_attr, attr)
 
@@ -1935,7 +1938,11 @@ static int __init cpufreq_core_init(void)
 		per_cpu(policy_cpu, cpu) = -1;
 		init_rwsem(&per_cpu(cpu_policy_rwsem, cpu));
 	}
+
+	cpufreq_global_kobject = kobject_create_and_add("cpufreq",
+						&cpu_sysdev_class.kset.kobj);
+	BUG_ON(!cpufreq_global_kobject);
+
 	return 0;
 }
-
 core_initcall(cpufreq_core_init);

include/linux/cpufreq.h

@@ -65,6 +65,9 @@ static inline int cpufreq_unregister_notifier(struct notifier_block *nb,
 
 struct cpufreq_governor;
 
+/* /sys/devices/system/cpu/cpufreq: entry point for global variables */
+extern struct kobject *cpufreq_global_kobject;
+
 #define CPUFREQ_ETERNAL			(-1)
 struct cpufreq_cpuinfo {
 	unsigned int		max_freq;
@@ -274,6 +277,13 @@ struct freq_attr {
 	ssize_t (*store)(struct cpufreq_policy *, const char *, size_t count);
 };
 
+struct global_attr {
+	struct attribute attr;
+	ssize_t (*show)(struct kobject *kobj,
+			struct attribute *attr, char *buf);
+	ssize_t (*store)(struct kobject *a, struct attribute *b,
+			 const char *c, size_t count);
+};
 
 /*********************************************************************
  *                        CPUFREQ 2.6. INTERFACE                     *