Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 1428 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
new file mode 100644
index 00000000000..b30001f3161
--- /dev/null
+++ b/drivers/cpufreq/cpufreq.c
@@ -0,0 +1,1428 @@
+/*
+ *  linux/drivers/cpufreq/cpufreq.c
+ *
+ *  Copyright (C) 2001 Russell King
+ *            (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
+ *
+ * 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/config.h>
+#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>
+
+#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_CORE, "cpufreq-core", msg)
+
+/**
+ * The "cpufreq driver" - the arch- or hardware-dependend 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 struct cpufreq_policy	*cpufreq_cpu_data[NR_CPUS];
+static DEFINE_SPINLOCK(cpufreq_driver_lock);
+
+
+/* we keep a copy of all ->add'ed CPU's struct sys_device here;
+ * as it is only accessed in ->add and ->remove, no lock or reference
+ * count is necessary.
+ */
+static struct sys_device	*cpu_sys_devices[NR_CPUS];
+
+
+/* internal prototypes */
+static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event);
+static void handle_update(void *data);
+static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci);
+
+/**
+ * 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 struct notifier_block    *cpufreq_policy_notifier_list;
+static struct notifier_block    *cpufreq_transition_notifier_list;
+static DECLARE_RWSEM		(cpufreq_notifier_rwsem);
+
+
+static LIST_HEAD(cpufreq_governor_list);
+static DECLARE_MUTEX		(cpufreq_governor_sem);
+
+struct cpufreq_policy * cpufreq_cpu_get(unsigned int cpu)
+{
+	struct cpufreq_policy *data;
+	unsigned long flags;
+
+	if (cpu >= NR_CPUS)
+		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 = 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);
+
+
+/*********************************************************************
+ *                     UNIFIED DEBUG HELPERS                         *
+ *********************************************************************/
+#ifdef CONFIG_CPU_FREQ_DEBUG
+
+/* what part(s) of the CPUfreq subsystem are debugged? */
+static unsigned int debug;
+
+/* is the debug output ratelimit'ed using printk_ratelimit? User can
+ * set or modify this value.
+ */
+static unsigned int debug_ratelimit = 1;
+
+/* is the printk_ratelimit'ing enabled? It's enabled after a successful
+ * loading of a cpufreq driver, temporarily disabled when a new policy
+ * is set, and disabled upon cpufreq driver removal
+ */
+static unsigned int disable_ratelimit = 1;
+static DEFINE_SPINLOCK(disable_ratelimit_lock);
+
+static inline void cpufreq_debug_enable_ratelimit(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&disable_ratelimit_lock, flags);
+	if (disable_ratelimit)
+		disable_ratelimit--;
+	spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
+}
+
+static inline void cpufreq_debug_disable_ratelimit(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&disable_ratelimit_lock, flags);
+	disable_ratelimit++;
+	spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
+}
+
+void cpufreq_debug_printk(unsigned int type, const char *prefix, const char *fmt, ...)
+{
+	char s[256];
+	va_list args;
+	unsigned int len;
+	unsigned long flags;
+	
+	WARN_ON(!prefix);
+	if (type & debug) {
+		spin_lock_irqsave(&disable_ratelimit_lock, flags);
+		if (!disable_ratelimit && debug_ratelimit && !printk_ratelimit()) {
+			spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
+			return;
+		}
+		spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
+
+		len = snprintf(s, 256, KERN_DEBUG "%s: ", prefix);
+
+		va_start(args, fmt);
+		len += vsnprintf(&s[len], (256 - len), fmt, args);
+		va_end(args);
+
+		printk(s);
+
+		WARN_ON(len < 5);
+	}
+}
+EXPORT_SYMBOL(cpufreq_debug_printk);
+
+
+module_param(debug, uint, 0644);
+MODULE_PARM_DESC(debug, "CPUfreq debugging: add 1 to debug core, 2 to debug drivers, and 4 to debug governors.");
+
+module_param(debug_ratelimit, uint, 0644);
+MODULE_PARM_DESC(debug_ratelimit, "CPUfreq debugging: set to 0 to disable ratelimiting.");
+
+#else /* !CONFIG_CPU_FREQ_DEBUG */
+
+static inline void cpufreq_debug_enable_ratelimit(void) { return; }
+static inline void cpufreq_debug_disable_ratelimit(void) { return; }
+
+#endif /* CONFIG_CPU_FREQ_DEBUG */
+
+
+/*********************************************************************
+ *            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 inline 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;
+		dprintk("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_PRECHANGE  && ci->old < ci->new) ||
+	    (val == CPUFREQ_POSTCHANGE && ci->old > ci->new) ||
+	    (val == CPUFREQ_RESUMECHANGE)) {
+		loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq, ci->new);
+		dprintk("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)
+{
+	BUG_ON(irqs_disabled());
+
+	freqs->flags = cpufreq_driver->flags;
+	dprintk("notification %u of frequency transition to %u kHz\n", state, freqs->new);
+
+	down_read(&cpufreq_notifier_rwsem);
+	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 ((likely(cpufreq_cpu_data[freqs->cpu])) &&
+			    (likely(cpufreq_cpu_data[freqs->cpu]->cpu == freqs->cpu)) &&
+			    (likely(cpufreq_cpu_data[freqs->cpu]->cur)) &&
+			    (unlikely(freqs->old != cpufreq_cpu_data[freqs->cpu]->cur)))
+			{
+				printk(KERN_WARNING "Warning: CPU frequency is %u, "
+				       "cpufreq assumed %u kHz.\n", freqs->old, cpufreq_cpu_data[freqs->cpu]->cur);
+				freqs->old = cpufreq_cpu_data[freqs->cpu]->cur;
+			}
+		}
+		notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_PRECHANGE, freqs);
+		adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
+		break;
+	case CPUFREQ_POSTCHANGE:
+		adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
+		notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_POSTCHANGE, freqs);
+		if ((likely(cpufreq_cpu_data[freqs->cpu])) && 
+		    (likely(cpufreq_cpu_data[freqs->cpu]->cpu == freqs->cpu)))
+			cpufreq_cpu_data[freqs->cpu]->cur = freqs->new;
+		break;
+	}
+	up_read(&cpufreq_notifier_rwsem);
+}
+EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
+
+
+
+/*********************************************************************
+ *                          SYSFS INTERFACE                          *
+ *********************************************************************/
+
+/**
+ * cpufreq_parse_governor - parse a governor string
+ */
+static int cpufreq_parse_governor (char *str_governor, unsigned int *policy,
+				struct cpufreq_governor **governor)
+{
+	if (!cpufreq_driver)
+		return -EINVAL;
+	if (cpufreq_driver->setpolicy) {
+		if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
+			*policy = CPUFREQ_POLICY_PERFORMANCE;
+			return 0;
+		} else if (!strnicmp(str_governor, "powersave", CPUFREQ_NAME_LEN)) {
+			*policy = CPUFREQ_POLICY_POWERSAVE;
+			return 0;
+		}
+		return -EINVAL;
+	} else {
+		struct cpufreq_governor *t;
+		down(&cpufreq_governor_sem);
+		if (!cpufreq_driver || !cpufreq_driver->target)
+			goto out;
+		list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
+			if (!strnicmp(str_governor,t->name,CPUFREQ_NAME_LEN)) {
+				*governor = t;
+				up(&cpufreq_governor_sem);
+				return 0;
+			}
+		}
+	out:
+		up(&cpufreq_governor_sem);
+	}
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_parse_governor);
+
+
+/* drivers/base/cpu.c */
+extern struct sysdev_class cpu_sysdev_class;
+
+
+/**
+ * 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(scaling_min_freq, min);
+show_one(scaling_max_freq, max);
+show_one(scaling_cur_freq, cur);
+
+/**
+ * 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(&new_policy);				\
+									\
+	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;
+
+	ret = cpufreq_set_policy(&new_policy);
+
+	return ret ? ret : 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;
+}
+/**
+ * show_affected_cpus - show the CPUs affected by each transition
+ */
+static ssize_t show_affected_cpus (struct cpufreq_policy * policy, char *buf)
+{
+	ssize_t i = 0;
+	unsigned int cpu;
+
+	for_each_cpu_mask(cpu, policy->cpus) {
+		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;
+}
+
+
+#define define_one_ro(_name) \
+static struct freq_attr _name = \
+__ATTR(_name, 0444, show_##_name, NULL)
+
+#define define_one_ro0400(_name) \
+static struct freq_attr _name = \
+__ATTR(_name, 0400, show_##_name, NULL)
+
+#define define_one_rw(_name) \
+static struct freq_attr _name = \
+__ATTR(_name, 0644, show_##_name, store_##_name)
+
+define_one_ro0400(cpuinfo_cur_freq);
+define_one_ro(cpuinfo_min_freq);
+define_one_ro(cpuinfo_max_freq);
+define_one_ro(scaling_available_governors);
+define_one_ro(scaling_driver);
+define_one_ro(scaling_cur_freq);
+define_one_ro(affected_cpus);
+define_one_rw(scaling_min_freq);
+define_one_rw(scaling_max_freq);
+define_one_rw(scaling_governor);
+
+static struct attribute * default_attrs[] = {
+	&cpuinfo_min_freq.attr,
+	&cpuinfo_max_freq.attr,
+	&scaling_min_freq.attr,
+	&scaling_max_freq.attr,
+	&affected_cpus.attr,
+	&scaling_governor.attr,
+	&scaling_driver.attr,
+	&scaling_available_governors.attr,
+	NULL
+};
+
+#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;
+	policy = cpufreq_cpu_get(policy->cpu);
+	if (!policy)
+		return -EINVAL;
+	ret = fattr->show ? fattr->show(policy,buf) : 0;
+	cpufreq_cpu_put(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;
+	policy = cpufreq_cpu_get(policy->cpu);
+	if (!policy)
+		return -EINVAL;
+	ret = fattr->store ? fattr->store(policy,buf,count) : 0;
+	cpufreq_cpu_put(policy);
+	return ret;
+}
+
+static void cpufreq_sysfs_release(struct kobject * kobj)
+{
+	struct cpufreq_policy * policy = to_policy(kobj);
+	dprintk("last reference is dropped\n");
+	complete(&policy->kobj_unregister);
+}
+
+static 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,
+};
+
+
+/**
+ * cpufreq_add_dev - add a CPU device
+ *
+ * Adds the cpufreq interface for a CPU device. 
+ */
+static int cpufreq_add_dev (struct sys_device * sys_dev)
+{
+	unsigned int cpu = sys_dev->id;
+	int ret = 0;
+	struct cpufreq_policy new_policy;
+	struct cpufreq_policy *policy;
+	struct freq_attr **drv_attr;
+	unsigned long flags;
+	unsigned int j;
+
+	cpufreq_debug_disable_ratelimit();
+	dprintk("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)) {
+		cpu_sys_devices[cpu] = sys_dev;
+		dprintk("CPU already managed, adding link\n");
+		sysfs_create_link(&sys_dev->kobj, &policy->kobj, "cpufreq");
+		cpufreq_debug_enable_ratelimit();
+		return 0;
+	}
+#endif
+
+	if (!try_module_get(cpufreq_driver->owner)) {
+		ret = -EINVAL;
+		goto module_out;
+	}
+
+	policy = kmalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
+	if (!policy) {
+		ret = -ENOMEM;
+		goto nomem_out;
+	}
+	memset(policy, 0, sizeof(struct cpufreq_policy));
+
+	policy->cpu = cpu;
+	policy->cpus = cpumask_of_cpu(cpu);
+
+	init_MUTEX_LOCKED(&policy->lock);
+	init_completion(&policy->kobj_unregister);
+	INIT_WORK(&policy->update, handle_update, (void *)(long)cpu);
+
+	/* 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) {
+		dprintk("initialization failed\n");
+		goto err_out;
+	}
+
+	memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
+
+	/* prepare interface data */
+	policy->kobj.parent = &sys_dev->kobj;
+	policy->kobj.ktype = &ktype_cpufreq;
+	strlcpy(policy->kobj.name, "cpufreq", KOBJ_NAME_LEN);
+
+	ret = kobject_register(&policy->kobj);
+	if (ret)
+		goto err_out;
+
+	/* set up files for this cpu device */
+	drv_attr = cpufreq_driver->attr;
+	while ((drv_attr) && (*drv_attr)) {
+		sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
+		drv_attr++;
+	}
+	if (cpufreq_driver->get)
+		sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
+	if (cpufreq_driver->target)
+		sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
+
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	for_each_cpu_mask(j, policy->cpus)
+		cpufreq_cpu_data[j] = policy;
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+	policy->governor = NULL; /* to assure that the starting sequence is
+				  * run in cpufreq_set_policy */
+	up(&policy->lock);
+	
+	/* set default policy */
+	
+	ret = cpufreq_set_policy(&new_policy);
+	if (ret) {
+		dprintk("setting policy failed\n");
+		goto err_out_unregister;
+	}
+
+	module_put(cpufreq_driver->owner);
+	cpu_sys_devices[cpu] = sys_dev;
+	dprintk("initialization complete\n");
+	cpufreq_debug_enable_ratelimit();
+	
+	return 0;
+
+
+err_out_unregister:
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	for_each_cpu_mask(j, policy->cpus)
+		cpufreq_cpu_data[j] = NULL;
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	kobject_unregister(&policy->kobj);
+	wait_for_completion(&policy->kobj_unregister);
+
+err_out:
+	kfree(policy);
+
+nomem_out:
+	module_put(cpufreq_driver->owner);
+ module_out:
+	cpufreq_debug_enable_ratelimit();
+	return ret;
+}
+
+
+/**
+ * cpufreq_remove_dev - remove a CPU device
+ *
+ * Removes the cpufreq interface for a CPU device.
+ */
+static int cpufreq_remove_dev (struct sys_device * sys_dev)
+{
+	unsigned int cpu = sys_dev->id;
+	unsigned long flags;
+	struct cpufreq_policy *data;
+#ifdef CONFIG_SMP
+	unsigned int j;
+#endif
+
+	cpufreq_debug_disable_ratelimit();
+	dprintk("unregistering CPU %u\n", cpu);
+
+	spin_lock_irqsave(&cpufreq_driver_lock, flags);
+	data = cpufreq_cpu_data[cpu];
+
+	if (!data) {
+		spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		cpu_sys_devices[cpu] = NULL;
+		cpufreq_debug_enable_ratelimit();
+		return -EINVAL;
+	}
+	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)) {
+		dprintk("removing link\n");
+		spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		sysfs_remove_link(&sys_dev->kobj, "cpufreq");
+		cpu_sys_devices[cpu] = NULL;
+		cpufreq_cpu_put(data);
+		cpufreq_debug_enable_ratelimit();
+		return 0;
+	}
+#endif
+
+	cpu_sys_devices[cpu] = NULL;
+
+	if (!kobject_get(&data->kobj)) {
+		spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		cpufreq_debug_enable_ratelimit();
+ 		return -EFAULT;
+	}
+
+#ifdef CONFIG_SMP
+	/* if we have other CPUs still registered, we need to unlink them,
+	 * or else wait_for_completion below will lock up. Clean the
+	 * cpufreq_cpu_data[] while holding the lock, and remove the sysfs
+	 * links afterwards.
+	 */
+	if (unlikely(cpus_weight(data->cpus) > 1)) {
+		for_each_cpu_mask(j, data->cpus) {
+			if (j == cpu)
+				continue;
+			cpufreq_cpu_data[j] = NULL;
+		}
+	}
+
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	if (unlikely(cpus_weight(data->cpus) > 1)) {
+		for_each_cpu_mask(j, data->cpus) {
+			if (j == cpu)
+				continue;
+			dprintk("removing link for cpu %u\n", j);
+			sysfs_remove_link(&cpu_sys_devices[j]->kobj, "cpufreq");
+			cpufreq_cpu_put(data);
+		}
+	}
+#else
+	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+#endif
+
+	down(&data->lock);
+	if (cpufreq_driver->target)
+		__cpufreq_governor(data, CPUFREQ_GOV_STOP);
+	cpufreq_driver->target = NULL;
+	up(&data->lock);
+
+	kobject_unregister(&data->kobj);
+
+	kobject_put(&data->kobj);
+
+	/* we need to make sure that the underlying kobj is actually
+	 * not referenced anymore by anybody before we proceed with 
+	 * unloading.
+	 */
+	dprintk("waiting for dropping of refcount\n");
+	wait_for_completion(&data->kobj_unregister);
+	dprintk("wait complete\n");
+
+	if (cpufreq_driver->exit)
+		cpufreq_driver->exit(data);
+
+	kfree(data);
+
+	cpufreq_debug_enable_ratelimit();
+
+	return 0;
+}
+
+
+static void handle_update(void *data)
+{
+	unsigned int cpu = (unsigned int)(long)data;
+	dprintk("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;
+
+	printk(KERN_WARNING "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_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)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	unsigned int ret = 0;
+
+	if (!policy)
+		return 0;
+
+	if (!cpufreq_driver->get)
+		goto out;
+
+	down(&policy->lock);
+
+	ret = cpufreq_driver->get(cpu);
+
+	if (ret && policy->cur && !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) 
+	{
+		/* verify no discrepancy between actual and saved value exists */
+		if (unlikely(ret != policy->cur)) {
+			cpufreq_out_of_sync(cpu, policy->cur, ret);
+			schedule_work(&policy->update);
+		}
+	}
+
+	up(&policy->lock);
+
+ out:
+	cpufreq_cpu_put(policy);
+
+	return (ret);
+}
+EXPORT_SYMBOL(cpufreq_get);
+
+
+/**
+ *	cpufreq_resume -  restore proper CPU frequency handling after resume
+ *
+ *	1.) resume CPUfreq hardware support (cpufreq_driver->resume())
+ *	2.) if ->target and !CPUFREQ_CONST_LOOPS: verify we're in sync
+ *	3.) schedule call cpufreq_update_policy() ASAP as interrupts are restored.
+ */
+static int cpufreq_resume(struct sys_device * sysdev)
+{
+	int cpu = sysdev->id;
+	unsigned int ret = 0;
+	struct cpufreq_policy *cpu_policy;
+
+	dprintk("resuming cpu %u\n", cpu);
+
+	if (!cpu_online(cpu))
+		return 0;
+
+	/* we may be lax here as interrupts are off. Nonetheless
+	 * we need to grab the correct cpu policy, as to check
+	 * whether we really run on this CPU.
+	 */
+
+	cpu_policy = cpufreq_cpu_get(cpu);
+	if (!cpu_policy)
+		return -EINVAL;
+
+	/* only handle each CPU group once */
+	if (unlikely(cpu_policy->cpu != cpu)) {
+		cpufreq_cpu_put(cpu_policy);
+		return 0;
+	}
+
+	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);
+			cpufreq_cpu_put(cpu_policy);
+			return ret;
+		}
+	}
+
+	if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
+		unsigned int cur_freq = 0;
+
+		if (cpufreq_driver->get)
+			cur_freq = cpufreq_driver->get(cpu_policy->cpu);
+
+		if (!cur_freq || !cpu_policy->cur) {
+			printk(KERN_ERR "cpufreq: resume failed to assert current frequency is what timing core thinks it is.\n");
+			goto out;
+		}
+
+		if (unlikely(cur_freq != cpu_policy->cur)) {
+			struct cpufreq_freqs freqs;
+
+			printk(KERN_WARNING "Warning: CPU frequency is %u, "
+			       "cpufreq assumed %u kHz.\n", cur_freq, cpu_policy->cur);
+
+			freqs.cpu = cpu;
+			freqs.old = cpu_policy->cur;
+			freqs.new = cur_freq;
+
+			notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_RESUMECHANGE, &freqs);
+			adjust_jiffies(CPUFREQ_RESUMECHANGE, &freqs);
+
+			cpu_policy->cur = cur_freq;
+		}
+	}
+
+out:
+	schedule_work(&cpu_policy->update);
+	cpufreq_cpu_put(cpu_policy);
+	return ret;
+}
+
+static struct sysdev_driver cpufreq_sysdev_driver = {
+	.add		= cpufreq_add_dev,
+	.remove		= cpufreq_remove_dev,
+	.resume		= cpufreq_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
+ *	notifier_chain_register.
+ */
+int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
+{
+	int ret;
+
+	down_write(&cpufreq_notifier_rwsem);
+	switch (list) {
+	case CPUFREQ_TRANSITION_NOTIFIER:
+		ret = notifier_chain_register(&cpufreq_transition_notifier_list, nb);
+		break;
+	case CPUFREQ_POLICY_NOTIFIER:
+		ret = notifier_chain_register(&cpufreq_policy_notifier_list, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	up_write(&cpufreq_notifier_rwsem);
+
+	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
+ *	notifier_chain_unregister.
+ */
+int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
+{
+	int ret;
+
+	down_write(&cpufreq_notifier_rwsem);
+	switch (list) {
+	case CPUFREQ_TRANSITION_NOTIFIER:
+		ret = notifier_chain_unregister(&cpufreq_transition_notifier_list, nb);
+		break;
+	case CPUFREQ_POLICY_NOTIFIER:
+		ret = notifier_chain_unregister(&cpufreq_policy_notifier_list, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+	up_write(&cpufreq_notifier_rwsem);
+
+	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;
+	lock_cpu_hotplug();
+	dprintk("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);
+	unlock_cpu_hotplug();
+	return retval;
+}
+EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
+
+
+int cpufreq_driver_target(struct cpufreq_policy *policy,
+			  unsigned int target_freq,
+			  unsigned int relation)
+{
+	unsigned int ret;
+
+	policy = cpufreq_cpu_get(policy->cpu);
+	if (!policy)
+		return -EINVAL;
+
+	down(&policy->lock);
+
+	ret = __cpufreq_driver_target(policy, target_freq, relation);
+
+	up(&policy->lock);
+
+	cpufreq_cpu_put(policy);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cpufreq_driver_target);
+
+
+static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event)
+{
+	int ret = -EINVAL;
+
+	if (!try_module_get(policy->governor->owner))
+		return -EINVAL;
+
+	dprintk("__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_governor(unsigned int cpu, unsigned int event)
+{
+	int ret = 0;
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+
+	if (!policy)
+		return -EINVAL;
+
+	down(&policy->lock);
+	ret = __cpufreq_governor(policy, event);
+	up(&policy->lock);
+
+	cpufreq_cpu_put(policy);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cpufreq_governor);
+
+
+int cpufreq_register_governor(struct cpufreq_governor *governor)
+{
+	struct cpufreq_governor *t;
+
+	if (!governor)
+		return -EINVAL;
+
+	down(&cpufreq_governor_sem);
+	
+	list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
+		if (!strnicmp(governor->name,t->name,CPUFREQ_NAME_LEN)) {
+			up(&cpufreq_governor_sem);
+			return -EBUSY;
+		}
+	}
+	list_add(&governor->governor_list, &cpufreq_governor_list);
+
+ 	up(&cpufreq_governor_sem);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cpufreq_register_governor);
+
+
+void cpufreq_unregister_governor(struct cpufreq_governor *governor)
+{
+	if (!governor)
+		return;
+
+	down(&cpufreq_governor_sem);
+	list_del(&governor->governor_list);
+	up(&cpufreq_governor_sem);
+	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;
+
+	down(&cpu_policy->lock);
+	memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
+	up(&cpu_policy->lock);
+
+	cpufreq_cpu_put(cpu_policy);
+
+	return 0;
+}
+EXPORT_SYMBOL(cpufreq_get_policy);
+
+
+static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_policy *policy)
+{
+	int ret = 0;
+
+	cpufreq_debug_disable_ratelimit();
+	dprintk("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));
+
+	/* verify the cpu speed can be set within this limit */
+	ret = cpufreq_driver->verify(policy);
+	if (ret)
+		goto error_out;
+
+	down_read(&cpufreq_notifier_rwsem);
+
+	/* adjust if necessary - all reasons */
+	notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_ADJUST,
+			    policy);
+
+	/* adjust if necessary - hardware incompatibility*/
+	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) {
+		up_read(&cpufreq_notifier_rwsem);
+		goto error_out;
+	}
+
+	/* notification of the new policy */
+	notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY,
+			    policy);
+
+	up_read(&cpufreq_notifier_rwsem);
+
+	data->min    = policy->min;
+	data->max    = policy->max;
+
+	dprintk("new min and max freqs are %u - %u kHz\n", data->min, data->max);
+
+	if (cpufreq_driver->setpolicy) {
+		data->policy = policy->policy;
+		dprintk("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;
+
+			dprintk("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 */
+				dprintk("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 */
+		}
+		dprintk("governor: change or update limits\n");
+		__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
+	}
+
+ error_out:
+	cpufreq_debug_enable_ratelimit();
+	return ret;
+}
+
+/**
+ *	cpufreq_set_policy - set a new CPUFreq policy
+ *	@policy: policy to be set.
+ *
+ *	Sets a new CPU frequency and voltage scaling policy.
+ */
+int cpufreq_set_policy(struct cpufreq_policy *policy)
+{
+	int ret = 0;
+	struct cpufreq_policy *data;
+
+	if (!policy)
+		return -EINVAL;
+
+	data = cpufreq_cpu_get(policy->cpu);
+	if (!data)
+		return -EINVAL;
+
+	/* lock this CPU */
+	down(&data->lock);
+
+	ret = __cpufreq_set_policy(data, policy);
+	data->user_policy.min = data->min;
+	data->user_policy.max = data->max;
+	data->user_policy.policy = data->policy;
+	data->user_policy.governor = data->governor;
+
+	up(&data->lock);
+	cpufreq_cpu_put(data);
+
+	return ret;
+}
+EXPORT_SYMBOL(cpufreq_set_policy);
+
+
+/**
+ *	cpufreq_update_policy - re-evaluate an existing cpufreq policy
+ *	@cpu: CPU which shall be re-evaluated
+ *
+ *	Usefull 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 = 0;
+
+	if (!data)
+		return -ENODEV;
+
+	down(&data->lock);
+
+	dprintk("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;
+
+	ret = __cpufreq_set_policy(data, &policy);
+
+	up(&data->lock);
+
+	cpufreq_cpu_put(data);
+	return ret;
+}
+EXPORT_SYMBOL(cpufreq_update_policy);
+
+
+/*********************************************************************
+ *               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 (!driver_data || !driver_data->verify || !driver_data->init ||
+	    ((!driver_data->setpolicy) && (!driver_data->target)))
+		return -EINVAL;
+
+	dprintk("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 = sysdev_driver_register(&cpu_sysdev_class,&cpufreq_sysdev_driver);
+
+	if ((!ret) && !(cpufreq_driver->flags & CPUFREQ_STICKY)) {
+		int i;
+		ret = -ENODEV;
+
+		/* check for at least one working CPU */
+		for (i=0; i<NR_CPUS; i++)
+			if (cpufreq_cpu_data[i])
+				ret = 0;
+
+		/* if all ->init() calls failed, unregister */
+		if (ret) {
+			dprintk("no CPU initialized for driver %s\n", driver_data->name);
+			sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
+
+			spin_lock_irqsave(&cpufreq_driver_lock, flags);
+			cpufreq_driver = NULL;
+			spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		}
+	}
+
+	if (!ret) {
+		dprintk("driver %s up and running\n", driver_data->name);
+		cpufreq_debug_enable_ratelimit();
+	}
+
+	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;
+
+	cpufreq_debug_disable_ratelimit();
+
+	if (!cpufreq_driver || (driver != cpufreq_driver)) {
+		cpufreq_debug_enable_ratelimit();
+		return -EINVAL;
+	}
+
+	dprintk("unregistering driver %s\n", driver->name);
+
+	sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
+
+	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);