init android origin source code

1 files changed, 1939 insertions, 0 deletions

diff --git a/ANDROID_3.4.5/drivers/cpufreq/cpufreq.c b/ANDROID_3.4.5/drivers/cpufreq/cpufreq.c
new file mode 100644
index 00000000..7f2f149a
--- /dev/null
+++ b/ANDROID_3.4.5/drivers/cpufreq/cpufreq.c
@@ -0,0 +1,1939 @@
+/*
+ *  linux/drivers/cpufreq/cpufreq.c
+ *
+ *  Copyright (C) 2001 Russell King
+ *            (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
+ *
+ *  Oct 2005 - Ashok Raj <ashok.raj@intel.com>
+ *	Added handling for CPU hotplug
+ *  Feb 2006 - Jacob Shin <jacob.shin@amd.com>
+ *	Fix handling for CPU hotplug -- affected CPUs
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/notifier.h>
+#include <linux/cpufreq.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/cpu.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/syscore_ops.h>
+
+#include <trace/events/power.h>
+
+/**
+ * The "cpufreq driver" - the arch- or hardware-dependent low
+ * level driver of CPUFreq support, and its spinlock. This lock
+ * also protects the cpufreq_cpu_data array.
+ */
+static struct cpufreq_driver *cpufreq_driver;
+static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
+#ifdef CONFIG_HOTPLUG_CPU
+/* This one keeps track of the previously set governor of a removed CPU */
+static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
+#endif
+static DEFINE_SPINLOCK(cpufreq_driver_lock);
+
+/*
+ * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
+ * all cpufreq/hotplug/workqueue/etc related lock issues.
+ *
+ * The rules for this semaphore:
+ * - Any routine that wants to read from the policy structure will
+ *   do a down_read on this semaphore.
+ * - Any routine that will write to the policy structure and/or may take away
+ *   the policy altogether (eg. CPU hotplug), will hold this lock in write
+ *   mode before doing so.
+ *
+ * Additional rules:
+ * - All holders of the lock should check to make sure that the CPU they
+ *   are concerned with are online after they get the lock.
+ * - Governor routines that can be called in cpufreq hotplug path should not
+ *   take this sem as top level hotplug notifier handler takes this.
+ * - Lock should not be held across
+ *     __cpufreq_governor(data, CPUFREQ_GOV_STOP);
+ */
+static DEFINE_PER_CPU(int, cpufreq_policy_cpu);
+static DEFINE_PER_CPU(struct rw_semaphore, cpu_policy_rwsem);
+
+#define lock_policy_rwsem(mode, cpu)					\
+static int lock_policy_rwsem_##mode					\
+(int cpu)								\
+{									\
+	int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);		\
+	BUG_ON(policy_cpu == -1);					\
+	down_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu));		\
+	if (unlikely(!cpu_online(cpu))) {				\
+		up_##mode(&per_cpu(cpu_policy_rwsem, policy_cpu));	\
+		return -1;						\
+	}								\
+									\
+	return 0;							\
+}
+
+lock_policy_rwsem(read, cpu);
+
+lock_policy_rwsem(write, cpu);
+
+static void unlock_policy_rwsem_read(int cpu)
+{
+	int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);
+	BUG_ON(policy_cpu == -1);
+	up_read(&per_cpu(cpu_policy_rwsem, policy_cpu));
+}
+
+static void unlock_policy_rwsem_write(int cpu)
+{
+	int policy_cpu = per_cpu(cpufreq_policy_cpu, cpu);
+	BUG_ON(policy_cpu == -1);
+	up_write(&per_cpu(cpu_policy_rwsem, policy_cpu));
+}
+
+
+/* internal prototypes */
+static int __cpufreq_governor(struct cpufreq_policy *policy,
+		unsigned int event);
+static unsigned int __cpufreq_get(unsigned int cpu);
+static void handle_update(struct work_struct *work);
+
+/**
+ * Two notifier lists: the "policy" list is involved in the
+ * validation process for a new CPU frequency policy; the
+ * "transition" list for kernel code that needs to handle
+ * changes to devices when the CPU clock speed changes.
+ * The mutex locks both lists.
+ */
+static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
+static struct srcu_notifier_head cpufreq_transition_notifier_list;
+
+static bool init_cpufreq_transition_notifier_list_called;
+static int __init init_cpufreq_transition_notifier_list(void)
+{
+	srcu_init_notifier_head(&cpufreq_transition_notifier_list);
+	init_cpufreq_transition_notifier_list_called = true;
+	return 0;
+}
+pure_initcall(init_cpufreq_transition_notifier_list);
+
+static int off __read_mostly;
+int cpufreq_disabled(void)
+{
+	return off;
+}
+void disable_cpufreq(void)
+{
+	off = 1;
+}
+static LIST_HEAD(cpufreq_governor_list);
+static DEFINE_MUTEX(cpufreq_governor_mutex);
+
+struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
+{
+	struct cpufreq_policy *data;
+	unsigned long flags;
+
+	if (cpu >= nr_cpu_ids)
+		goto err_out;
+
+	/* get the cpufreq driver */
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+
+	if (!cpufreq_driver)
+		goto err_out_unlock;
+
+	if (!try_module_get(cpufreq_driver->owner))
+		goto err_out_unlock;
+
+
+	/* get the CPU */
+	data = per_cpu(cpufreq_cpu_data, cpu);
+
+	if (!data)
+		goto err_out_put_module;
+
+	if (!kobject_get(&data->kobj))
+		goto err_out_put_module;
+
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+	return data;
+
+err_out_put_module:
+	module_put(cpufreq_driver->owner);
+err_out_unlock:
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+err_out:
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
+
+
+void cpufreq_cpu_put(struct cpufreq_policy *data)
+{
+	kobject_put(&data->kobj);
+	module_put(cpufreq_driver->owner);
+}
+EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
+
+
+/*********************************************************************
+ *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
+ *********************************************************************/
+
+/**
+ * adjust_jiffies - adjust the system "loops_per_jiffy"
+ *
+ * This function alters the system "loops_per_jiffy" for the clock
+ * speed change. Note that loops_per_jiffy cannot be updated on SMP
+ * systems as each CPU might be scaled differently. So, use the arch
+ * per-CPU loops_per_jiffy value wherever possible.
+ */
+#ifndef CONFIG_SMP
+static unsigned long l_p_j_ref;
+static unsigned int  l_p_j_ref_freq;
+
+static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
+{
+	if (ci->flags & CPUFREQ_CONST_LOOPS)
+		return;
+
+	if (!l_p_j_ref_freq) {
+		l_p_j_ref = loops_per_jiffy;
+		l_p_j_ref_freq = ci->old;
+		pr_debug("saving %lu as reference value for loops_per_jiffy; "
+			"freq is %u kHz\n", l_p_j_ref, l_p_j_ref_freq);
+	}
+	if ((val == CPUFREQ_POSTCHANGE  && ci->old != ci->new) ||
+	    (val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE)) {
+		loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq,
+								ci->new);
+		pr_debug("scaling loops_per_jiffy to %lu "
+			"for frequency %u kHz\n", loops_per_jiffy, ci->new);
+	}
+}
+#else
+static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
+{
+	return;
+}
+#endif
+
+
+/**
+ * cpufreq_notify_transition - call notifier chain and adjust_jiffies
+ * on frequency transition.
+ *
+ * This function calls the transition notifiers and the "adjust_jiffies"
+ * function. It is called twice on all CPU frequency changes that have
+ * external effects.
+ */
+void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
+{
+	struct cpufreq_policy *policy;
+
+	BUG_ON(irqs_disabled());
+
+	freqs->flags = cpufreq_driver->flags;
+	pr_debug("notification %u of frequency transition to %u kHz\n",
+		state, freqs->new);
+
+	policy = per_cpu(cpufreq_cpu_data, freqs->cpu);
+	switch (state) {
+
+	case CPUFREQ_PRECHANGE:
+		/* detect if the driver reported a value as "old frequency"
+		 * which is not equal to what the cpufreq core thinks is
+		 * "old frequency".
+		 */
+		if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
+			if ((policy) && (policy->cpu == freqs->cpu) &&
+			    (policy->cur) && (policy->cur != freqs->old)) {
+				pr_debug("Warning: CPU frequency is"
+					" %u, cpufreq assumed %u kHz.\n",
+					freqs->old, policy->cur);
+				freqs->old = policy->cur;
+			}
+		}
+		srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
+				CPUFREQ_PRECHANGE, freqs);
+		adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
+		break;
+
+	case CPUFREQ_POSTCHANGE:
+		adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
+		pr_debug("FREQ: %lu - CPU: %lu", (unsigned long)freqs->new,
+			(unsigned long)freqs->cpu);
+		trace_power_frequency(POWER_PSTATE, freqs->new, freqs->cpu);
+		trace_cpu_frequency(freqs->new, freqs->cpu);
+		srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
+				CPUFREQ_POSTCHANGE, freqs);
+		if (likely(policy) && likely(policy->cpu == freqs->cpu))
+			policy->cur = freqs->new;
+		break;
+	}
+}
+EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
+
+
+
+/*********************************************************************
+ *                          SYSFS INTERFACE                          *
+ *********************************************************************/
+
+static struct cpufreq_governor *__find_governor(const char *str_governor)
+{
+	struct cpufreq_governor *t;
+
+	list_for_each_entry(t, &cpufreq_governor_list, governor_list)
+		if (!strnicmp(str_governor, t->name, CPUFREQ_NAME_LEN))
+			return t;
+
+	return NULL;
+}
+
+/**
+ * cpufreq_parse_governor - parse a governor string
+ */
+static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
+				struct cpufreq_governor **governor)
+{
+	int err = -EINVAL;
+
+	if (!cpufreq_driver)
+		goto out;
+
+	if (cpufreq_driver->setpolicy) {
+		if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
+			*policy = CPUFREQ_POLICY_PERFORMANCE;
+			err = 0;
+		} else if (!strnicmp(str_governor, "powersave",
+						CPUFREQ_NAME_LEN)) {
+			*policy = CPUFREQ_POLICY_POWERSAVE;
+			err = 0;
+		}
+	} else if (cpufreq_driver->target) {
+		struct cpufreq_governor *t;
+
+		mutex_lock(&cpufreq_governor_mutex);
+
+		t = __find_governor(str_governor);
+
+		if (t == NULL) {
+			int ret;
+
+			mutex_unlock(&cpufreq_governor_mutex);
+			ret = request_module("cpufreq_%s", str_governor);
+			mutex_lock(&cpufreq_governor_mutex);
+
+			if (ret == 0)
+				t = __find_governor(str_governor);
+		}
+
+		if (t != NULL) {
+			*governor = t;
+			err = 0;
+		}
+
+		mutex_unlock(&cpufreq_governor_mutex);
+	}
+out:
+	return err;
+}
+
+
+/**
+ * cpufreq_per_cpu_attr_read() / show_##file_name() -
+ * print out cpufreq information
+ *
+ * Write out information from cpufreq_driver->policy[cpu]; object must be
+ * "unsigned int".
+ */
+
+#define show_one(file_name, object)			\
+static ssize_t show_##file_name				\
+(struct cpufreq_policy *policy, char *buf)		\
+{							\
+	return sprintf(buf, "%u\n", policy->object);	\
+}
+
+show_one(cpuinfo_min_freq, cpuinfo.min_freq);
+show_one(cpuinfo_max_freq, cpuinfo.max_freq);
+show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
+show_one(scaling_min_freq, min);
+show_one(scaling_max_freq, max);
+show_one(scaling_cur_freq, cur);
+
+static int __cpufreq_set_policy(struct cpufreq_policy *data,
+				struct cpufreq_policy *policy);
+
+/**
+ * cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
+ */
+#define store_one(file_name, object)			\
+static ssize_t store_##file_name					\
+(struct cpufreq_policy *policy, const char *buf, size_t count)		\
+{									\
+	unsigned int ret = -EINVAL;					\
+	struct cpufreq_policy new_policy;				\
+									\
+	ret = cpufreq_get_policy(&new_policy, policy->cpu);		\
+	if (ret)							\
+		return -EINVAL;						\
+									\
+	ret = sscanf(buf, "%u", &new_policy.object);			\
+	if (ret != 1)							\
+		return -EINVAL;						\
+									\
+	ret = __cpufreq_set_policy(policy, &new_policy);		\
+	policy->user_policy.object = policy->object;			\
+									\
+	return ret ? ret : count;					\
+}
+
+store_one(scaling_min_freq, min);
+store_one(scaling_max_freq, max);
+
+/**
+ * show_cpuinfo_cur_freq - current CPU frequency as detected by hardware
+ */
+static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
+					char *buf)
+{
+	unsigned int cur_freq = __cpufreq_get(policy->cpu);
+	if (!cur_freq)
+		return sprintf(buf, "<unknown>");
+	return sprintf(buf, "%u\n", cur_freq);
+}
+
+
+/**
+ * show_scaling_governor - show the current policy for the specified CPU
+ */
+static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf)
+{
+	if (policy->policy == CPUFREQ_POLICY_POWERSAVE)
+		return sprintf(buf, "powersave\n");
+	else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
+		return sprintf(buf, "performance\n");
+	else if (policy->governor)
+		return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n",
+				policy->governor->name);
+	return -EINVAL;
+}
+
+
+/**
+ * store_scaling_governor - store policy for the specified CPU
+ */
+static ssize_t store_scaling_governor(struct cpufreq_policy *policy,
+					const char *buf, size_t count)
+{
+	unsigned int ret = -EINVAL;
+	char	str_governor[16];
+	struct cpufreq_policy new_policy;
+
+	ret = cpufreq_get_policy(&new_policy, policy->cpu);
+	if (ret)
+		return ret;
+
+	ret = sscanf(buf, "%15s", str_governor);
+	if (ret != 1)
+		return -EINVAL;
+
+	if (cpufreq_parse_governor(str_governor, &new_policy.policy,
+						&new_policy.governor))
+		return -EINVAL;
+
+	/* Do not use cpufreq_set_policy here or the user_policy.max
+	   will be wrongly overridden */
+	ret = __cpufreq_set_policy(policy, &new_policy);
+
+	policy->user_policy.policy = policy->policy;
+	policy->user_policy.governor = policy->governor;
+
+	if (ret)
+		return ret;
+	else
+		return count;
+}
+
+/**
+ * show_scaling_driver - show the cpufreq driver currently loaded
+ */
+static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
+{
+	return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n", cpufreq_driver->name);
+}
+
+/**
+ * show_scaling_available_governors - show the available CPUfreq governors
+ */
+static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
+						char *buf)
+{
+	ssize_t i = 0;
+	struct cpufreq_governor *t;
+
+	if (!cpufreq_driver->target) {
+		i += sprintf(buf, "performance powersave");
+		goto out;
+	}
+
+	list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
+		if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
+		    - (CPUFREQ_NAME_LEN + 2)))
+			goto out;
+		i += scnprintf(&buf[i], CPUFREQ_NAME_LEN, "%s ", t->name);
+	}
+out:
+	i += sprintf(&buf[i], "\n");
+	return i;
+}
+
+static ssize_t show_cpus(const struct cpumask *mask, char *buf)
+{
+	ssize_t i = 0;
+	unsigned int cpu;
+
+	for_each_cpu(cpu, mask) {
+		if (i)
+			i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), " ");
+		i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u", cpu);
+		if (i >= (PAGE_SIZE - 5))
+			break;
+	}
+	i += sprintf(&buf[i], "\n");
+	return i;
+}
+
+/**
+ * show_related_cpus - show the CPUs affected by each transition even if
+ * hw coordination is in use
+ */
+static ssize_t show_related_cpus(struct cpufreq_policy *policy, char *buf)
+{
+	if (cpumask_empty(policy->related_cpus))
+		return show_cpus(policy->cpus, buf);
+	return show_cpus(policy->related_cpus, buf);
+}
+
+/**
+ * show_affected_cpus - show the CPUs affected by each transition
+ */
+static ssize_t show_affected_cpus(struct cpufreq_policy *policy, char *buf)
+{
+	return show_cpus(policy->cpus, buf);
+}
+
+static ssize_t store_scaling_setspeed(struct cpufreq_policy *policy,
+					const char *buf, size_t count)
+{
+	unsigned int freq = 0;
+	unsigned int ret;
+
+	if (!policy->governor || !policy->governor->store_setspeed)
+		return -EINVAL;
+
+	ret = sscanf(buf, "%u", &freq);
+	if (ret != 1)
+		return -EINVAL;
+
+	policy->governor->store_setspeed(policy, freq);
+
+	return count;
+}
+
+static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
+{
+	if (!policy->governor || !policy->governor->show_setspeed)
+		return sprintf(buf, "<unsupported>\n");
+
+	return policy->governor->show_setspeed(policy, buf);
+}
+
+/**
+ * show_scaling_driver - show the current cpufreq HW/BIOS limitation
+ */
+static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
+{
+	unsigned int limit;
+	int ret;
+	if (cpufreq_driver->bios_limit) {
+		ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
+		if (!ret)
+			return sprintf(buf, "%u\n", limit);
+	}
+	return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
+}
+
+cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);
+cpufreq_freq_attr_ro(cpuinfo_min_freq);
+cpufreq_freq_attr_ro(cpuinfo_max_freq);
+cpufreq_freq_attr_ro(cpuinfo_transition_latency);
+cpufreq_freq_attr_ro(scaling_available_governors);
+cpufreq_freq_attr_ro(scaling_driver);
+cpufreq_freq_attr_ro(scaling_cur_freq);
+cpufreq_freq_attr_ro(bios_limit);
+cpufreq_freq_attr_ro(related_cpus);
+cpufreq_freq_attr_ro(affected_cpus);
+cpufreq_freq_attr_rw(scaling_min_freq);
+cpufreq_freq_attr_rw(scaling_max_freq);
+cpufreq_freq_attr_rw(scaling_governor);
+cpufreq_freq_attr_rw(scaling_setspeed);
+
+static struct attribute *default_attrs[] = {
+	&cpuinfo_min_freq.attr,
+	&cpuinfo_max_freq.attr,
+	&cpuinfo_transition_latency.attr,
+	&scaling_min_freq.attr,
+	&scaling_max_freq.attr,
+	&affected_cpus.attr,
+	&related_cpus.attr,
+	&scaling_governor.attr,
+	&scaling_driver.attr,
+	&scaling_available_governors.attr,
+	&scaling_setspeed.attr,
+	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)
+
+static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+	struct cpufreq_policy *policy = to_policy(kobj);
+	struct freq_attr *fattr = to_attr(attr);
+	ssize_t ret = -EINVAL;
+	policy = cpufreq_cpu_get(policy->cpu);
+	if (!policy)
+		goto no_policy;
+
+	if (lock_policy_rwsem_read(policy->cpu) < 0)
+		goto fail;
+
+	if (fattr->show)
+		ret = fattr->show(policy, buf);
+	else
+		ret = -EIO;
+
+	unlock_policy_rwsem_read(policy->cpu);
+fail:
+	cpufreq_cpu_put(policy);
+no_policy:
+	return ret;
+}
+
+static ssize_t store(struct kobject *kobj, struct attribute *attr,
+		     const char *buf, size_t count)
+{
+	struct cpufreq_policy *policy = to_policy(kobj);
+	struct freq_attr *fattr = to_attr(attr);
+	ssize_t ret = -EINVAL;
+	policy = cpufreq_cpu_get(policy->cpu);
+	if (!policy)
+		goto no_policy;
+
+	if (lock_policy_rwsem_write(policy->cpu) < 0)
+		goto fail;
+
+	if (fattr->store)
+		ret = fattr->store(policy, buf, count);
+	else
+		ret = -EIO;
+
+	unlock_policy_rwsem_write(policy->cpu);
+fail:
+	cpufreq_cpu_put(policy);
+no_policy:
+	return ret;
+}
+
+static void cpufreq_sysfs_release(struct kobject *kobj)
+{
+	struct cpufreq_policy *policy = to_policy(kobj);
+	pr_debug("last reference is dropped\n");
+	complete(&policy->kobj_unregister);
+}
+
+static const struct sysfs_ops sysfs_ops = {
+	.show	= show,
+	.store	= store,
+};
+
+static struct kobj_type ktype_cpufreq = {
+	.sysfs_ops	= &sysfs_ops,
+	.default_attrs	= default_attrs,
+	.release	= cpufreq_sysfs_release,
+};
+
+/*
+ * Returns:
+ *   Negative: Failure
+ *   0:        Success
+ *   Positive: When we have a managed CPU and the sysfs got symlinked
+ */
+static int cpufreq_add_dev_policy(unsigned int cpu,
+				  struct cpufreq_policy *policy,
+				  struct device *dev)
+{
+	int ret = 0;
+#ifdef CONFIG_SMP
+	unsigned long flags;
+	unsigned int j;
+#ifdef CONFIG_HOTPLUG_CPU
+	struct cpufreq_governor *gov;
+
+	gov = __find_governor(per_cpu(cpufreq_cpu_governor, cpu));
+	if (gov) {
+		policy->governor = gov;
+		pr_debug("Restoring governor %s for cpu %d\n",
+		       policy->governor->name, cpu);
+	}
+#endif
+
+	for_each_cpu(j, policy->cpus) {
+		struct cpufreq_policy *managed_policy;
+
+		if (cpu == j)
+			continue;
+
+		/* Check for existing affected CPUs.
+		 * They may not be aware of it due to CPU Hotplug.
+		 * cpufreq_cpu_put is called when the device is removed
+		 * in __cpufreq_remove_dev()
+		 */
+		managed_policy = cpufreq_cpu_get(j);
+		if (unlikely(managed_policy)) {
+
+			/* Set proper policy_cpu */
+			unlock_policy_rwsem_write(cpu);
+			per_cpu(cpufreq_policy_cpu, cpu) = managed_policy->cpu;
+
+			if (lock_policy_rwsem_write(cpu) < 0) {
+				/* Should not go through policy unlock path */
+				if (cpufreq_driver->exit)
+					cpufreq_driver->exit(policy);
+				cpufreq_cpu_put(managed_policy);
+				return -EBUSY;
+			}
+
+			spin_lock_irqsave(&cpufreq_driver_lock, flags);
+			cpumask_copy(managed_policy->cpus, policy->cpus);
+			per_cpu(cpufreq_cpu_data, cpu) = managed_policy;
+			spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+			pr_debug("CPU already managed, adding link\n");
+			ret = sysfs_create_link(&dev->kobj,
+						&managed_policy->kobj,
+						"cpufreq");
+			if (ret)
+				cpufreq_cpu_put(managed_policy);
+			/*
+			 * Success. We only needed to be added to the mask.
+			 * Call driver->exit() because only the cpu parent of
+			 * the kobj needed to call init().
+			 */
+			if (cpufreq_driver->exit)
+				cpufreq_driver->exit(policy);
+
+			if (!ret)
+				return 1;
+			else
+				return ret;
+		}
+	}
+#endif
+	return ret;
+}
+
+
+/* symlink affected CPUs */
+static int cpufreq_add_dev_symlink(unsigned int cpu,
+				   struct cpufreq_policy *policy)
+{
+	unsigned int j;
+	int ret = 0;
+
+	for_each_cpu(j, policy->cpus) {
+		struct cpufreq_policy *managed_policy;
+		struct device *cpu_dev;
+
+		if (j == cpu)
+			continue;
+		if (!cpu_online(j))
+			continue;
+
+		pr_debug("CPU %u already managed, adding link\n", j);
+		managed_policy = cpufreq_cpu_get(cpu);
+		cpu_dev = get_cpu_device(j);
+		ret = sysfs_create_link(&cpu_dev->kobj, &policy->kobj,
+					"cpufreq");
+		if (ret) {
+			cpufreq_cpu_put(managed_policy);
+			return ret;
+		}
+	}
+	return ret;
+}
+
+static int cpufreq_add_dev_interface(unsigned int cpu,
+				     struct cpufreq_policy *policy,
+				     struct device *dev)
+{
+	struct cpufreq_policy new_policy;
+	struct freq_attr **drv_attr;
+	unsigned long flags;
+	int ret = 0;
+	unsigned int j;
+
+	/* prepare interface data */
+	ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
+				   &dev->kobj, "cpufreq");
+	if (ret)
+		return ret;
+
+	/* set up files for this cpu device */
+	drv_attr = cpufreq_driver->attr;
+	while ((drv_attr) && (*drv_attr)) {
+		ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
+		if (ret)
+			goto err_out_kobj_put;
+		drv_attr++;
+	}
+	if (cpufreq_driver->get) {
+		ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
+		if (ret)
+			goto err_out_kobj_put;
+	}
+	if (cpufreq_driver->target) {
+		ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
+		if (ret)
+			goto err_out_kobj_put;
+	}
+	if (cpufreq_driver->bios_limit) {
+		ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
+		if (ret)
+			goto err_out_kobj_put;
+	}
+
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	for_each_cpu(j, policy->cpus) {
+		if (!cpu_online(j))
+			continue;
+		per_cpu(cpufreq_cpu_data, j) = policy;
+		per_cpu(cpufreq_policy_cpu, j) = policy->cpu;
+	}
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	ret = cpufreq_add_dev_symlink(cpu, policy);
+	if (ret)
+		goto err_out_kobj_put;
+
+	memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
+	/* assure that the starting sequence is run in __cpufreq_set_policy */
+	policy->governor = NULL;
+
+	/* set default policy */
+	ret = __cpufreq_set_policy(policy, &new_policy);
+	policy->user_policy.policy = policy->policy;
+	policy->user_policy.governor = policy->governor;
+
+	if (ret) {
+		pr_debug("setting policy failed\n");
+		if (cpufreq_driver->exit)
+			cpufreq_driver->exit(policy);
+	}
+	return ret;
+
+err_out_kobj_put:
+	kobject_put(&policy->kobj);
+	wait_for_completion(&policy->kobj_unregister);
+	return ret;
+}
+
+
+/**
+ * cpufreq_add_dev - add a CPU device
+ *
+ * Adds the cpufreq interface for a CPU device.
+ *
+ * The Oracle says: try running cpufreq registration/unregistration concurrently
+ * with with cpu hotplugging and all hell will break loose. Tried to clean this
+ * mess up, but more thorough testing is needed. - Mathieu
+ */
+static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
+{
+	unsigned int cpu = dev->id;
+	int ret = 0, found = 0;
+	struct cpufreq_policy *policy;
+	unsigned long flags;
+	unsigned int j;
+#ifdef CONFIG_HOTPLUG_CPU
+	int sibling;
+#endif
+
+	if (cpu_is_offline(cpu))
+		return 0;
+
+	pr_debug("adding CPU %u\n", cpu);
+
+#ifdef CONFIG_SMP
+	/* check whether a different CPU already registered this
+	 * CPU because it is in the same boat. */
+	policy = cpufreq_cpu_get(cpu);
+	if (unlikely(policy)) {
+		cpufreq_cpu_put(policy);
+		return 0;
+	}
+#endif
+
+	if (!try_module_get(cpufreq_driver->owner)) {
+		ret = -EINVAL;
+		goto module_out;
+	}
+
+	ret = -ENOMEM;
+	policy = kzalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
+	if (!policy)
+		goto nomem_out;
+
+	if (!alloc_cpumask_var(&policy->cpus, GFP_KERNEL))
+		goto err_free_policy;
+
+	if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL))
+		goto err_free_cpumask;
+
+	policy->cpu = cpu;
+	cpumask_copy(policy->cpus, cpumask_of(cpu));
+
+	/* Initially set CPU itself as the policy_cpu */
+	per_cpu(cpufreq_policy_cpu, cpu) = cpu;
+	ret = (lock_policy_rwsem_write(cpu) < 0);
+	WARN_ON(ret);
+
+	init_completion(&policy->kobj_unregister);
+	INIT_WORK(&policy->update, handle_update);
+
+	/* Set governor before ->init, so that driver could check it */
+#ifdef CONFIG_HOTPLUG_CPU
+	for_each_online_cpu(sibling) {
+		struct cpufreq_policy *cp = per_cpu(cpufreq_cpu_data, sibling);
+		if (cp && cp->governor &&
+		    (cpumask_test_cpu(cpu, cp->related_cpus))) {
+			policy->governor = cp->governor;
+			found = 1;
+			break;
+		}
+	}
+#endif
+	if (!found)
+		policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+	/* call driver. From then on the cpufreq must be able
+	 * to accept all calls to ->verify and ->setpolicy for this CPU
+	 */
+	ret = cpufreq_driver->init(policy);
+	if (ret) {
+		pr_debug("initialization failed\n");
+		goto err_unlock_policy;
+	}
+	policy->user_policy.min = policy->min;
+	policy->user_policy.max = policy->max;
+
+	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+				     CPUFREQ_START, policy);
+
+	ret = cpufreq_add_dev_policy(cpu, policy, dev);
+	if (ret) {
+		if (ret > 0)
+			/* This is a managed cpu, symlink created,
+			   exit with 0 */
+			ret = 0;
+		goto err_unlock_policy;
+	}
+
+	ret = cpufreq_add_dev_interface(cpu, policy, dev);
+	if (ret)
+		goto err_out_unregister;
+
+	unlock_policy_rwsem_write(cpu);
+
+	kobject_uevent(&policy->kobj, KOBJ_ADD);
+	module_put(cpufreq_driver->owner);
+	pr_debug("initialization complete\n");
+
+	return 0;
+
+
+err_out_unregister:
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	for_each_cpu(j, policy->cpus)
+		per_cpu(cpufreq_cpu_data, j) = NULL;
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	kobject_put(&policy->kobj);
+	wait_for_completion(&policy->kobj_unregister);
+
+err_unlock_policy:
+	unlock_policy_rwsem_write(cpu);
+	free_cpumask_var(policy->related_cpus);
+err_free_cpumask:
+	free_cpumask_var(policy->cpus);
+err_free_policy:
+	kfree(policy);
+nomem_out:
+	module_put(cpufreq_driver->owner);
+module_out:
+	return ret;
+}
+
+
+/**
+ * __cpufreq_remove_dev - remove a CPU device
+ *
+ * Removes the cpufreq interface for a CPU device.
+ * Caller should already have policy_rwsem in write mode for this CPU.
+ * This routine frees the rwsem before returning.
+ */
+static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
+{
+	unsigned int cpu = dev->id;
+	unsigned long flags;
+	struct cpufreq_policy *data;
+	struct kobject *kobj;
+	struct completion *cmp;
+#ifdef CONFIG_SMP
+	struct device *cpu_dev;
+	unsigned int j;
+#endif
+
+	pr_debug("unregistering CPU %u\n", cpu);
+
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	data = per_cpu(cpufreq_cpu_data, cpu);
+
+	if (!data) {
+		spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		unlock_policy_rwsem_write(cpu);
+		return -EINVAL;
+	}
+	per_cpu(cpufreq_cpu_data, cpu) = NULL;
+
+
+#ifdef CONFIG_SMP
+	/* if this isn't the CPU which is the parent of the kobj, we
+	 * only need to unlink, put and exit
+	 */
+	if (unlikely(cpu != data->cpu)) {
+		pr_debug("removing link\n");
+		cpumask_clear_cpu(cpu, data->cpus);
+		spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		kobj = &dev->kobj;
+		cpufreq_cpu_put(data);
+		unlock_policy_rwsem_write(cpu);
+		sysfs_remove_link(kobj, "cpufreq");
+		return 0;
+	}
+#endif
+
+#ifdef CONFIG_SMP
+
+#ifdef CONFIG_HOTPLUG_CPU
+	strncpy(per_cpu(cpufreq_cpu_governor, cpu), data->governor->name,
+			CPUFREQ_NAME_LEN);
+#endif
+
+	/* if we have other CPUs still registered, we need to unlink them,
+	 * or else wait_for_completion below will lock up. Clean the
+	 * per_cpu(cpufreq_cpu_data) while holding the lock, and remove
+	 * the sysfs links afterwards.
+	 */
+	if (unlikely(cpumask_weight(data->cpus) > 1)) {
+		for_each_cpu(j, data->cpus) {
+			if (j == cpu)
+				continue;
+			per_cpu(cpufreq_cpu_data, j) = NULL;
+		}
+	}
+
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	if (unlikely(cpumask_weight(data->cpus) > 1)) {
+		for_each_cpu(j, data->cpus) {
+			if (j == cpu)
+				continue;
+			pr_debug("removing link for cpu %u\n", j);
+#ifdef CONFIG_HOTPLUG_CPU
+			strncpy(per_cpu(cpufreq_cpu_governor, j),
+				data->governor->name, CPUFREQ_NAME_LEN);
+#endif
+			cpu_dev = get_cpu_device(j);
+			kobj = &cpu_dev->kobj;
+			unlock_policy_rwsem_write(cpu);
+			sysfs_remove_link(kobj, "cpufreq");
+			lock_policy_rwsem_write(cpu);
+			cpufreq_cpu_put(data);
+		}
+	}
+#else
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+#endif
+
+	if (cpufreq_driver->target)
+		__cpufreq_governor(data, CPUFREQ_GOV_STOP);
+
+	kobj = &data->kobj;
+	cmp = &data->kobj_unregister;
+	unlock_policy_rwsem_write(cpu);
+	kobject_put(kobj);
+
+	/* we need to make sure that the underlying kobj is actually
+	 * not referenced anymore by anybody before we proceed with
+	 * unloading.
+	 */
+	pr_debug("waiting for dropping of refcount\n");
+	wait_for_completion(cmp);
+	pr_debug("wait complete\n");
+
+	lock_policy_rwsem_write(cpu);
+	if (cpufreq_driver->exit)
+		cpufreq_driver->exit(data);
+	unlock_policy_rwsem_write(cpu);
+
+#ifdef CONFIG_HOTPLUG_CPU
+	/* when the CPU which is the parent of the kobj is hotplugged
+	 * offline, check for siblings, and create cpufreq sysfs interface
+	 * and symlinks
+	 */
+	if (unlikely(cpumask_weight(data->cpus) > 1)) {
+		/* first sibling now owns the new sysfs dir */
+		cpumask_clear_cpu(cpu, data->cpus);
+		cpufreq_add_dev(get_cpu_device(cpumask_first(data->cpus)), NULL);
+
+		/* finally remove our own symlink */
+		lock_policy_rwsem_write(cpu);
+		__cpufreq_remove_dev(dev, sif);
+	}
+#endif
+
+	free_cpumask_var(data->related_cpus);
+	free_cpumask_var(data->cpus);
+	kfree(data);
+
+	return 0;
+}
+
+
+static int cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
+{
+	unsigned int cpu = dev->id;
+	int retval;
+
+	if (cpu_is_offline(cpu))
+		return 0;
+
+	if (unlikely(lock_policy_rwsem_write(cpu)))
+		BUG();
+
+	retval = __cpufreq_remove_dev(dev, sif);
+	return retval;
+}
+
+
+static void handle_update(struct work_struct *work)
+{
+	struct cpufreq_policy *policy =
+		container_of(work, struct cpufreq_policy, update);
+	unsigned int cpu = policy->cpu;
+	pr_debug("handle_update for cpu %u called\n", cpu);
+	cpufreq_update_policy(cpu);
+}
+
+/**
+ *	cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're in deep trouble.
+ *	@cpu: cpu number
+ *	@old_freq: CPU frequency the kernel thinks the CPU runs at
+ *	@new_freq: CPU frequency the CPU actually runs at
+ *
+ *	We adjust to current frequency first, and need to clean up later.
+ *	So either call to cpufreq_update_policy() or schedule handle_update()).
+ */
+static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq,
+				unsigned int new_freq)
+{
+	struct cpufreq_freqs freqs;
+
+	pr_debug("Warning: CPU frequency out of sync: cpufreq and timing "
+	       "core thinks of %u, is %u kHz.\n", old_freq, new_freq);
+
+	freqs.cpu = cpu;
+	freqs.old = old_freq;
+	freqs.new = new_freq;
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+}
+
+
+/**
+ * cpufreq_quick_get - get the CPU frequency (in kHz) from policy->cur
+ * @cpu: CPU number
+ *
+ * This is the last known freq, without actually getting it from the driver.
+ * Return value will be same as what is shown in scaling_cur_freq in sysfs.
+ */
+unsigned int cpufreq_quick_get(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	unsigned int ret_freq = 0;
+
+	if (policy) {
+		ret_freq = policy->cur;
+		cpufreq_cpu_put(policy);
+	}
+
+	return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_quick_get);
+
+/**
+ * cpufreq_quick_get_max - get the max reported CPU frequency for this CPU
+ * @cpu: CPU number
+ *
+ * Just return the max possible frequency for a given CPU.
+ */
+unsigned int cpufreq_quick_get_max(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	unsigned int ret_freq = 0;
+
+	if (policy) {
+		ret_freq = policy->max;
+		cpufreq_cpu_put(policy);
+	}
+
+	return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_quick_get_max);
+
+
+static unsigned int __cpufreq_get(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
+	unsigned int ret_freq = 0;
+
+	if (!cpufreq_driver->get)
+		return ret_freq;
+
+	ret_freq = cpufreq_driver->get(cpu);
+
+	if (ret_freq && policy->cur &&
+		!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
+		/* verify no discrepancy between actual and
+					saved value exists */
+		if (unlikely(ret_freq != policy->cur)) {
+			cpufreq_out_of_sync(cpu, policy->cur, ret_freq);
+			schedule_work(&policy->update);
+		}
+	}
+
+	return ret_freq;
+}
+
+/**
+ * cpufreq_get - get the current CPU frequency (in kHz)
+ * @cpu: CPU number
+ *
+ * Get the CPU current (static) CPU frequency
+ */
+unsigned int cpufreq_get(unsigned int cpu)
+{
+	unsigned int ret_freq = 0;
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+
+	if (!policy)
+		goto out;
+
+	if (unlikely(lock_policy_rwsem_read(cpu)))
+		goto out_policy;
+
+	ret_freq = __cpufreq_get(cpu);
+
+	unlock_policy_rwsem_read(cpu);
+
+out_policy:
+	cpufreq_cpu_put(policy);
+out:
+	return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_get);
+
+static struct subsys_interface cpufreq_interface = {
+	.name		= "cpufreq",
+	.subsys		= &cpu_subsys,
+	.add_dev	= cpufreq_add_dev,
+	.remove_dev	= cpufreq_remove_dev,
+};
+
+
+/**
+ * cpufreq_bp_suspend - Prepare the boot CPU for system suspend.
+ *
+ * This function is only executed for the boot processor.  The other CPUs
+ * have been put offline by means of CPU hotplug.
+ */
+static int cpufreq_bp_suspend(void)
+{
+	int ret = 0;
+
+	int cpu = smp_processor_id();
+	struct cpufreq_policy *cpu_policy;
+
+	pr_debug("suspending cpu %u\n", cpu);
+
+	/* If there's no policy for the boot CPU, we have nothing to do. */
+	cpu_policy = cpufreq_cpu_get(cpu);
+	if (!cpu_policy)
+		return 0;
+
+	if (cpufreq_driver->suspend) {
+		ret = cpufreq_driver->suspend(cpu_policy);
+		if (ret)
+			printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
+					"step on CPU %u\n", cpu_policy->cpu);
+	}
+
+	cpufreq_cpu_put(cpu_policy);
+	return ret;
+}
+
+/**
+ * cpufreq_bp_resume - Restore proper frequency handling of the boot CPU.
+ *
+ *	1.) resume CPUfreq hardware support (cpufreq_driver->resume())
+ *	2.) schedule call cpufreq_update_policy() ASAP as interrupts are
+ *	    restored. It will verify that the current freq is in sync with
+ *	    what we believe it to be. This is a bit later than when it
+ *	    should be, but nonethteless it's better than calling
+ *	    cpufreq_driver->get() here which might re-enable interrupts...
+ *
+ * This function is only executed for the boot CPU.  The other CPUs have not
+ * been turned on yet.
+ */
+static void cpufreq_bp_resume(void)
+{
+	int ret = 0;
+
+	int cpu = smp_processor_id();
+	struct cpufreq_policy *cpu_policy;
+
+	pr_debug("resuming cpu %u\n", cpu);
+
+	/* If there's no policy for the boot CPU, we have nothing to do. */
+	cpu_policy = cpufreq_cpu_get(cpu);
+	if (!cpu_policy)
+		return;
+
+	if (cpufreq_driver->resume) {
+		ret = cpufreq_driver->resume(cpu_policy);
+		if (ret) {
+			printk(KERN_ERR "cpufreq: resume failed in ->resume "
+					"step on CPU %u\n", cpu_policy->cpu);
+			goto fail;
+		}
+	}
+
+	schedule_work(&cpu_policy->update);
+
+fail:
+	cpufreq_cpu_put(cpu_policy);
+}
+
+static struct syscore_ops cpufreq_syscore_ops = {
+	.suspend	= cpufreq_bp_suspend,
+	.resume		= cpufreq_bp_resume,
+};
+
+
+/*********************************************************************
+ *                     NOTIFIER LISTS INTERFACE                      *
+ *********************************************************************/
+
+/**
+ *	cpufreq_register_notifier - register a driver with cpufreq
+ *	@nb: notifier function to register
+ *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
+ *
+ *	Add a driver to one of two lists: either a list of drivers that
+ *      are notified about clock rate changes (once before and once after
+ *      the transition), or a list of drivers that are notified about
+ *      changes in cpufreq policy.
+ *
+ *	This function may sleep, and has the same return conditions as
+ *	blocking_notifier_chain_register.
+ */
+int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
+{
+	int ret;
+
+	WARN_ON(!init_cpufreq_transition_notifier_list_called);
+
+	switch (list) {
+	case CPUFREQ_TRANSITION_NOTIFIER:
+		ret = srcu_notifier_chain_register(
+				&cpufreq_transition_notifier_list, nb);
+		break;
+	case CPUFREQ_POLICY_NOTIFIER:
+		ret = blocking_notifier_chain_register(
+				&cpufreq_policy_notifier_list, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(cpufreq_register_notifier);
+
+
+/**
+ *	cpufreq_unregister_notifier - unregister a driver with cpufreq
+ *	@nb: notifier block to be unregistered
+ *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
+ *
+ *	Remove a driver from the CPU frequency notifier list.
+ *
+ *	This function may sleep, and has the same return conditions as
+ *	blocking_notifier_chain_unregister.
+ */
+int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
+{
+	int ret;
+
+	switch (list) {
+	case CPUFREQ_TRANSITION_NOTIFIER:
+		ret = srcu_notifier_chain_unregister(
+				&cpufreq_transition_notifier_list, nb);
+		break;
+	case CPUFREQ_POLICY_NOTIFIER:
+		ret = blocking_notifier_chain_unregister(
+				&cpufreq_policy_notifier_list, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(cpufreq_unregister_notifier);
+
+
+/*********************************************************************
+ *                              GOVERNORS                            *
+ *********************************************************************/
+
+
+int __cpufreq_driver_target(struct cpufreq_policy *policy,
+			    unsigned int target_freq,
+			    unsigned int relation)
+{
+	int retval = -EINVAL;
+
+	if (cpufreq_disabled())
+		return -ENODEV;
+
+	pr_debug("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
+		target_freq, relation);
+	if (cpu_online(policy->cpu) && cpufreq_driver->target)
+		retval = cpufreq_driver->target(policy, target_freq, relation);
+
+	return retval;
+}
+EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
+
+int cpufreq_driver_target(struct cpufreq_policy *policy,
+			  unsigned int target_freq,
+			  unsigned int relation)
+{
+	int ret = -EINVAL;
+
+	policy = cpufreq_cpu_get(policy->cpu);
+	if (!policy)
+		goto no_policy;
+
+	if (unlikely(lock_policy_rwsem_write(policy->cpu)))
+		goto fail;
+
+	ret = __cpufreq_driver_target(policy, target_freq, relation);
+
+	unlock_policy_rwsem_write(policy->cpu);
+
+fail:
+	cpufreq_cpu_put(policy);
+no_policy:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cpufreq_driver_target);
+
+int __cpufreq_driver_getavg(struct cpufreq_policy *policy, unsigned int cpu)
+{
+	int ret = 0;
+
+	policy = cpufreq_cpu_get(policy->cpu);
+	if (!policy)
+		return -EINVAL;
+
+	if (cpu_online(cpu) && cpufreq_driver->getavg)
+		ret = cpufreq_driver->getavg(policy, cpu);
+
+	cpufreq_cpu_put(policy);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__cpufreq_driver_getavg);
+
+/*
+ * when "event" is CPUFREQ_GOV_LIMITS
+ */
+
+static int __cpufreq_governor(struct cpufreq_policy *policy,
+					unsigned int event)
+{
+	int ret;
+
+	/* Only must be defined when default governor is known to have latency
+	   restrictions, like e.g. conservative or ondemand.
+	   That this is the case is already ensured in Kconfig
+	*/
+#ifdef CONFIG_CPU_FREQ_GOV_PERFORMANCE
+	struct cpufreq_governor *gov = &cpufreq_gov_performance;
+#else
+	struct cpufreq_governor *gov = NULL;
+#endif
+
+	if (policy->governor->max_transition_latency &&
+	    policy->cpuinfo.transition_latency >
+	    policy->governor->max_transition_latency) {
+		if (!gov)
+			return -EINVAL;
+		else {
+			printk(KERN_WARNING "%s governor failed, too long"
+			       " transition latency of HW, fallback"
+			       " to %s governor\n",
+			       policy->governor->name,
+			       gov->name);
+			policy->governor = gov;
+		}
+	}
+
+	if (!try_module_get(policy->governor->owner))
+		return -EINVAL;
+
+	pr_debug("__cpufreq_governor for CPU %u, event %u\n",
+						policy->cpu, event);
+	ret = policy->governor->governor(policy, event);
+
+	/* we keep one module reference alive for
+			each CPU governed by this CPU */
+	if ((event != CPUFREQ_GOV_START) || ret)
+		module_put(policy->governor->owner);
+	if ((event == CPUFREQ_GOV_STOP) && !ret)
+		module_put(policy->governor->owner);
+
+	return ret;
+}
+
+
+int cpufreq_register_governor(struct cpufreq_governor *governor)
+{
+	int err;
+
+	if (!governor)
+		return -EINVAL;
+
+	if (cpufreq_disabled())
+		return -ENODEV;
+
+	mutex_lock(&cpufreq_governor_mutex);
+
+	err = -EBUSY;
+	if (__find_governor(governor->name) == NULL) {
+		err = 0;
+		list_add(&governor->governor_list, &cpufreq_governor_list);
+	}
+
+	mutex_unlock(&cpufreq_governor_mutex);
+	return err;
+}
+EXPORT_SYMBOL_GPL(cpufreq_register_governor);
+
+
+void cpufreq_unregister_governor(struct cpufreq_governor *governor)
+{
+#ifdef CONFIG_HOTPLUG_CPU
+	int cpu;
+#endif
+
+	if (!governor)
+		return;
+
+	if (cpufreq_disabled())
+		return;
+
+#ifdef CONFIG_HOTPLUG_CPU
+	for_each_present_cpu(cpu) {
+		if (cpu_online(cpu))
+			continue;
+		if (!strcmp(per_cpu(cpufreq_cpu_governor, cpu), governor->name))
+			strcpy(per_cpu(cpufreq_cpu_governor, cpu), "\0");
+	}
+#endif
+
+	mutex_lock(&cpufreq_governor_mutex);
+	list_del(&governor->governor_list);
+	mutex_unlock(&cpufreq_governor_mutex);
+	return;
+}
+EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
+
+
+
+/*********************************************************************
+ *                          POLICY INTERFACE                         *
+ *********************************************************************/
+
+/**
+ * cpufreq_get_policy - get the current cpufreq_policy
+ * @policy: struct cpufreq_policy into which the current cpufreq_policy
+ *	is written
+ *
+ * Reads the current cpufreq policy.
+ */
+int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
+{
+	struct cpufreq_policy *cpu_policy;
+	if (!policy)
+		return -EINVAL;
+
+	cpu_policy = cpufreq_cpu_get(cpu);
+	if (!cpu_policy)
+		return -EINVAL;
+
+	memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
+
+	cpufreq_cpu_put(cpu_policy);
+	return 0;
+}
+EXPORT_SYMBOL(cpufreq_get_policy);
+
+
+/*
+ * data   : current policy.
+ * policy : policy to be set.
+ */
+static int __cpufreq_set_policy(struct cpufreq_policy *data,
+				struct cpufreq_policy *policy)
+{
+	int ret = 0;
+
+	pr_debug("setting new policy for CPU %u: %u - %u kHz\n", policy->cpu,
+		policy->min, policy->max);
+
+	memcpy(&policy->cpuinfo, &data->cpuinfo,
+				sizeof(struct cpufreq_cpuinfo));
+
+	if (policy->min > data->max || policy->max < data->min) {
+		ret = -EINVAL;
+		goto error_out;
+	}
+
+	/* verify the cpu speed can be set within this limit */
+	ret = cpufreq_driver->verify(policy);
+	if (ret)
+		goto error_out;
+
+	/* adjust if necessary - all reasons */
+	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+			CPUFREQ_ADJUST, policy);
+
+	/* adjust if necessary - hardware incompatibility*/
+	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+			CPUFREQ_INCOMPATIBLE, policy);
+
+	/* verify the cpu speed can be set within this limit,
+	   which might be different to the first one */
+	ret = cpufreq_driver->verify(policy);
+	if (ret)
+		goto error_out;
+
+	/* notification of the new policy */
+	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+			CPUFREQ_NOTIFY, policy);
+
+	data->min = policy->min;
+	data->max = policy->max;
+
+	pr_debug("new min and max freqs are %u - %u kHz\n",
+					data->min, data->max);
+
+	if (cpufreq_driver->setpolicy) {
+		data->policy = policy->policy;
+		pr_debug("setting range\n");
+		ret = cpufreq_driver->setpolicy(policy);
+	} else {
+		if (policy->governor != data->governor) {
+			/* save old, working values */
+			struct cpufreq_governor *old_gov = data->governor;
+
+			pr_debug("governor switch\n");
+
+			/* end old governor */
+			if (data->governor)
+				__cpufreq_governor(data, CPUFREQ_GOV_STOP);
+
+			/* start new governor */
+			data->governor = policy->governor;
+			if (__cpufreq_governor(data, CPUFREQ_GOV_START)) {
+				/* new governor failed, so re-start old one */
+				pr_debug("starting governor %s failed\n",
+							data->governor->name);
+				if (old_gov) {
+					data->governor = old_gov;
+					__cpufreq_governor(data,
+							   CPUFREQ_GOV_START);
+				}
+				ret = -EINVAL;
+				goto error_out;
+			}
+			/* might be a policy change, too, so fall through */
+		}
+		pr_debug("governor: change or update limits\n");
+		__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
+	}
+
+error_out:
+	return ret;
+}
+
+/**
+ *	cpufreq_update_policy - re-evaluate an existing cpufreq policy
+ *	@cpu: CPU which shall be re-evaluated
+ *
+ *	Useful for policy notifiers which have different necessities
+ *	at different times.
+ */
+int cpufreq_update_policy(unsigned int cpu)
+{
+	struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
+	struct cpufreq_policy policy;
+	int ret;
+
+	if (!data) {
+		ret = -ENODEV;
+		goto no_policy;
+	}
+
+	if (unlikely(lock_policy_rwsem_write(cpu))) {
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	pr_debug("updating policy for CPU %u\n", cpu);
+	memcpy(&policy, data, sizeof(struct cpufreq_policy));
+	policy.min = data->user_policy.min;
+	policy.max = data->user_policy.max;
+	policy.policy = data->user_policy.policy;
+	policy.governor = data->user_policy.governor;
+
+	/* BIOS might change freq behind our back
+	  -> ask driver for current freq and notify governors about a change */
+	if (cpufreq_driver->get) {
+		policy.cur = cpufreq_driver->get(cpu);
+		if (!data->cur) {
+			pr_debug("Driver did not initialize current freq");
+			data->cur = policy.cur;
+		} else {
+			if (data->cur != policy.cur)
+				cpufreq_out_of_sync(cpu, data->cur,
+								policy.cur);
+		}
+	}
+
+	ret = __cpufreq_set_policy(data, &policy);
+
+	unlock_policy_rwsem_write(cpu);
+
+fail:
+	cpufreq_cpu_put(data);
+no_policy:
+	return ret;
+}
+EXPORT_SYMBOL(cpufreq_update_policy);
+
+static int __cpuinit cpufreq_cpu_callback(struct notifier_block *nfb,
+					unsigned long action, void *hcpu)
+{
+	unsigned int cpu = (unsigned long)hcpu;
+	struct device *dev;
+
+	dev = get_cpu_device(cpu);
+	if (dev) {
+		switch (action) {
+		case CPU_ONLINE:
+		case CPU_ONLINE_FROZEN:
+			cpufreq_add_dev(dev, NULL);
+			break;
+		case CPU_DOWN_PREPARE:
+		case CPU_DOWN_PREPARE_FROZEN:
+			if (unlikely(lock_policy_rwsem_write(cpu)))
+				BUG();
+
+			__cpufreq_remove_dev(dev, NULL);
+			break;
+		case CPU_DOWN_FAILED:
+		case CPU_DOWN_FAILED_FROZEN:
+			cpufreq_add_dev(dev, NULL);
+			break;
+		}
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block __refdata cpufreq_cpu_notifier = {
+    .notifier_call = cpufreq_cpu_callback,
+};
+
+/*********************************************************************
+ *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
+ *********************************************************************/
+
+/**
+ * cpufreq_register_driver - register a CPU Frequency driver
+ * @driver_data: A struct cpufreq_driver containing the values#
+ * submitted by the CPU Frequency driver.
+ *
+ *   Registers a CPU Frequency driver to this core code. This code
+ * returns zero on success, -EBUSY when another driver got here first
+ * (and isn't unregistered in the meantime).
+ *
+ */
+int cpufreq_register_driver(struct cpufreq_driver *driver_data)
+{
+	unsigned long flags;
+	int ret;
+
+	if (cpufreq_disabled())
+		return -ENODEV;
+
+	if (!driver_data || !driver_data->verify || !driver_data->init ||
+	    ((!driver_data->setpolicy) && (!driver_data->target)))
+		return -EINVAL;
+
+	pr_debug("trying to register driver %s\n", driver_data->name);
+
+	if (driver_data->setpolicy)
+		driver_data->flags |= CPUFREQ_CONST_LOOPS;
+
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	if (cpufreq_driver) {
+		spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		return -EBUSY;
+	}
+	cpufreq_driver = driver_data;
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	ret = subsys_interface_register(&cpufreq_interface);
+	if (ret)
+		goto err_null_driver;
+
+	if (!(cpufreq_driver->flags & CPUFREQ_STICKY)) {
+		int i;
+		ret = -ENODEV;
+
+		/* check for at least one working CPU */
+		for (i = 0; i < nr_cpu_ids; i++)
+			if (cpu_possible(i) && per_cpu(cpufreq_cpu_data, i)) {
+				ret = 0;
+				break;
+			}
+
+		/* if all ->init() calls failed, unregister */
+		if (ret) {
+			pr_debug("no CPU initialized for driver %s\n",
+							driver_data->name);
+			goto err_if_unreg;
+		}
+	}
+
+	register_hotcpu_notifier(&cpufreq_cpu_notifier);
+	pr_debug("driver %s up and running\n", driver_data->name);
+
+	return 0;
+err_if_unreg:
+	subsys_interface_unregister(&cpufreq_interface);
+err_null_driver:
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	cpufreq_driver = NULL;
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cpufreq_register_driver);
+
+
+/**
+ * cpufreq_unregister_driver - unregister the current CPUFreq driver
+ *
+ *    Unregister the current CPUFreq driver. Only call this if you have
+ * the right to do so, i.e. if you have succeeded in initialising before!
+ * Returns zero if successful, and -EINVAL if the cpufreq_driver is
+ * currently not initialised.
+ */
+int cpufreq_unregister_driver(struct cpufreq_driver *driver)
+{
+	unsigned long flags;
+
+	if (!cpufreq_driver || (driver != cpufreq_driver))
+		return -EINVAL;
+
+	pr_debug("unregistering driver %s\n", driver->name);
+
+	subsys_interface_unregister(&cpufreq_interface);
+	unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
+
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	cpufreq_driver = NULL;
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
+
+static int __init cpufreq_core_init(void)
+{
+	int cpu;
+
+	if (cpufreq_disabled())
+		return -ENODEV;
+
+	for_each_possible_cpu(cpu) {
+		per_cpu(cpufreq_policy_cpu, cpu) = -1;
+		init_rwsem(&per_cpu(cpu_policy_rwsem, cpu));
+	}
+
+	cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj);
+	BUG_ON(!cpufreq_global_kobject);
+	register_syscore_ops(&cpufreq_syscore_ops);
+
+	return 0;
+}
+core_initcall(cpufreq_core_init);