diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
new file mode 100644
index 0000000..f3100b1
--- /dev/null
+++ b/drivers/devfreq/devfreq.c
@@ -0,0 +1,532 @@
+/*
+ * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
+ *	    for Non-CPU Devices.
+ *
+ * Copyright (C) 2011 Samsung Electronics
+ *	MyungJoo Ham <myungjoo.ham@samsung.com>
+ *
+ * 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/sched.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/opp.h>
+#include <linux/devfreq.h>
+#include <linux/workqueue.h>
+#include <linux/platform_device.h>
+#include <linux/list.h>
+#include <linux/printk.h>
+#include <linux/hrtimer.h>
+#include "governor.h"
+
+struct class *devfreq_class;
+
+/*
+ * devfreq_work periodically monitors every registered device.
+ * The minimum polling interval is one jiffy. The polling interval is
+ * determined by the minimum polling period among all polling devfreq
+ * devices. The resolution of polling interval is one jiffy.
+ */
+static bool polling;
+static struct workqueue_struct *devfreq_wq;
+static struct delayed_work devfreq_work;
+
+/* wait removing if this is to be removed */
+static struct devfreq *wait_remove_device;
+
+/* The list of all device-devfreq */
+static LIST_HEAD(devfreq_list);
+static DEFINE_MUTEX(devfreq_list_lock);
+
+/**
+ * find_device_devfreq() - find devfreq struct using device pointer
+ * @dev:	device pointer used to lookup device devfreq.
+ *
+ * Search the list of device devfreqs and return the matched device's
+ * devfreq info. devfreq_list_lock should be held by the caller.
+ */
+static struct devfreq *find_device_devfreq(struct device *dev)
+{
+	struct devfreq *tmp_devfreq;
+
+	if (unlikely(IS_ERR_OR_NULL(dev))) {
+		pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+	WARN(!mutex_is_locked(&devfreq_list_lock),
+	     "devfreq_list_lock must be locked.");
+
+	list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
+		if (tmp_devfreq->dev.parent == dev)
+			return tmp_devfreq;
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+
+/**
+ * update_devfreq() - Reevaluate the device and configure frequency.
+ * @devfreq:	the devfreq instance.
+ *
+ * Note: Lock devfreq->lock before calling update_devfreq
+ *	 This function is exported for governors.
+ */
+int update_devfreq(struct devfreq *devfreq)
+{
+	unsigned long freq;
+	int err = 0;
+
+	if (!mutex_is_locked(&devfreq->lock)) {
+		WARN(true, "devfreq->lock must be locked by the caller.\n");
+		return -EINVAL;
+	}
+
+	/* Reevaluate the proper frequency */
+	err = devfreq->governor->get_target_freq(devfreq, &freq);
+	if (err)
+		return err;
+
+	err = devfreq->profile->target(devfreq->dev.parent, &freq);
+	if (err)
+		return err;
+
+	devfreq->previous_freq = freq;
+	return err;
+}
+
+/**
+ * devfreq_notifier_call() - Notify that the device frequency requirements
+ *			   has been changed out of devfreq framework.
+ * @nb		the notifier_block (supposed to be devfreq->nb)
+ * @type	not used
+ * @devp	not used
+ *
+ * Called by a notifier that uses devfreq->nb.
+ */
+static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
+				 void *devp)
+{
+	struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
+	int ret;
+
+	mutex_lock(&devfreq->lock);
+	ret = update_devfreq(devfreq);
+	mutex_unlock(&devfreq->lock);
+
+	return ret;
+}
+
+/**
+ * _remove_devfreq() - Remove devfreq from the device.
+ * @devfreq:	the devfreq struct
+ * @skip:	skip calling device_unregister().
+ *
+ * Note that the caller should lock devfreq->lock before calling
+ * this. _remove_devfreq() will unlock it and free devfreq
+ * internally. devfreq_list_lock should be locked by the caller
+ * as well (not relased at return)
+ *
+ * Lock usage:
+ * devfreq->lock: locked before call.
+ *		  unlocked at return (and freed)
+ * devfreq_list_lock: locked before call.
+ *		      kept locked at return.
+ *		      if devfreq is centrally polled.
+ *
+ * Freed memory:
+ * devfreq
+ */
+static void _remove_devfreq(struct devfreq *devfreq, bool skip)
+{
+	if (!mutex_is_locked(&devfreq->lock)) {
+		WARN(true, "devfreq->lock must be locked by the caller.\n");
+		return;
+	}
+	if (!devfreq->governor->no_central_polling &&
+	    !mutex_is_locked(&devfreq_list_lock)) {
+		WARN(true, "devfreq_list_lock must be locked by the caller.\n");
+		return;
+	}
+
+	if (devfreq->being_removed)
+		return;
+
+	devfreq->being_removed = true;
+
+	if (devfreq->profile->exit)
+		devfreq->profile->exit(devfreq->dev.parent);
+
+	if (devfreq->governor->exit)
+		devfreq->governor->exit(devfreq);
+
+	if (!skip && get_device(&devfreq->dev)) {
+		device_unregister(&devfreq->dev);
+		put_device(&devfreq->dev);
+	}
+
+	if (!devfreq->governor->no_central_polling)
+		list_del(&devfreq->node);
+
+	mutex_unlock(&devfreq->lock);
+	mutex_destroy(&devfreq->lock);
+
+	kfree(devfreq);
+}
+
+/**
+ * devfreq_dev_release() - Callback for struct device to release the device.
+ * @dev:	the devfreq device
+ *
+ * This calls _remove_devfreq() if _remove_devfreq() is not called.
+ * Note that devfreq_dev_release() could be called by _remove_devfreq() as
+ * well as by others unregistering the device.
+ */
+static void devfreq_dev_release(struct device *dev)
+{
+	struct devfreq *devfreq = to_devfreq(dev);
+	bool central_polling = !devfreq->governor->no_central_polling;
+
+	/*
+	 * If devfreq_dev_release() was called by device_unregister() of
+	 * _remove_devfreq(), we cannot mutex_lock(&devfreq->lock) and
+	 * being_removed is already set. This also partially checks the case
+	 * where devfreq_dev_release() is called from a thread other than
+	 * the one called _remove_devfreq(); however, this case is
+	 * dealt completely with another following being_removed check.
+	 *
+	 * Because being_removed is never being
+	 * unset, we do not need to worry about race conditions on
+	 * being_removed.
+	 */
+	if (devfreq->being_removed)
+		return;
+
+	if (central_polling)
+		mutex_lock(&devfreq_list_lock);
+
+	mutex_lock(&devfreq->lock);
+
+	/*
+	 * Check being_removed flag again for the case where
+	 * devfreq_dev_release() was called in a thread other than the one
+	 * possibly called _remove_devfreq().
+	 */
+	if (devfreq->being_removed) {
+		mutex_unlock(&devfreq->lock);
+		goto out;
+	}
+
+	/* devfreq->lock is unlocked and removed in _removed_devfreq() */
+	_remove_devfreq(devfreq, true);
+
+out:
+	if (central_polling)
+		mutex_unlock(&devfreq_list_lock);
+}
+
+/**
+ * devfreq_monitor() - Periodically poll devfreq objects.
+ * @work: the work struct used to run devfreq_monitor periodically.
+ *
+ */
+static void devfreq_monitor(struct work_struct *work)
+{
+	static unsigned long last_polled_at;
+	struct devfreq *devfreq, *tmp;
+	int error;
+	unsigned long jiffies_passed;
+	unsigned long next_jiffies = ULONG_MAX, now = jiffies;
+	struct device *dev;
+
+	/* Initially last_polled_at = 0, polling every device at bootup */
+	jiffies_passed = now - last_polled_at;
+	last_polled_at = now;
+	if (jiffies_passed == 0)
+		jiffies_passed = 1;
+
+	mutex_lock(&devfreq_list_lock);
+	list_for_each_entry_safe(devfreq, tmp, &devfreq_list, node) {
+		mutex_lock(&devfreq->lock);
+		dev = devfreq->dev.parent;
+
+		/* Do not remove tmp for a while */
+		wait_remove_device = tmp;
+
+		if (devfreq->governor->no_central_polling ||
+		    devfreq->next_polling == 0) {
+			mutex_unlock(&devfreq->lock);
+			continue;
+		}
+		mutex_unlock(&devfreq_list_lock);
+
+		/*
+		 * Reduce more next_polling if devfreq_wq took an extra
+		 * delay. (i.e., CPU has been idled.)
+		 */
+		if (devfreq->next_polling <= jiffies_passed) {
+			error = update_devfreq(devfreq);
+
+			/* Remove a devfreq with an error. */
+			if (error && error != -EAGAIN) {
+
+				dev_err(dev, "Due to update_devfreq error(%d), devfreq(%s) is removed from the device\n",
+					error, devfreq->governor->name);
+
+				/*
+				 * Unlock devfreq before locking the list
+				 * in order to avoid deadlock with
+				 * find_device_devfreq or others
+				 */
+				mutex_unlock(&devfreq->lock);
+				mutex_lock(&devfreq_list_lock);
+				/* Check if devfreq is already removed */
+				if (IS_ERR(find_device_devfreq(dev)))
+					continue;
+				mutex_lock(&devfreq->lock);
+				/* This unlocks devfreq->lock and free it */
+				_remove_devfreq(devfreq, false);
+				continue;
+			}
+			devfreq->next_polling = devfreq->polling_jiffies;
+		} else {
+			devfreq->next_polling -= jiffies_passed;
+		}
+
+		if (devfreq->next_polling)
+			next_jiffies = (next_jiffies > devfreq->next_polling) ?
+					devfreq->next_polling : next_jiffies;
+
+		mutex_unlock(&devfreq->lock);
+		mutex_lock(&devfreq_list_lock);
+	}
+	wait_remove_device = NULL;
+	mutex_unlock(&devfreq_list_lock);
+
+	if (next_jiffies > 0 && next_jiffies < ULONG_MAX) {
+		polling = true;
+		queue_delayed_work(devfreq_wq, &devfreq_work, next_jiffies);
+	} else {
+		polling = false;
+	}
+}
+
+/**
+ * devfreq_add_device() - Add devfreq feature to the device
+ * @dev:	the device to add devfreq feature.
+ * @profile:	device-specific profile to run devfreq.
+ * @governor:	the policy to choose frequency.
+ * @data:	private data for the governor. The devfreq framework does not
+ *		touch this value.
+ */
+struct devfreq *devfreq_add_device(struct device *dev,
+				   struct devfreq_dev_profile *profile,
+				   const struct devfreq_governor *governor,
+				   void *data)
+{
+	struct devfreq *devfreq;
+	int err = 0;
+
+	if (!dev || !profile || !governor) {
+		dev_err(dev, "%s: Invalid parameters.\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+
+
+	if (!governor->no_central_polling) {
+		mutex_lock(&devfreq_list_lock);
+		devfreq = find_device_devfreq(dev);
+		mutex_unlock(&devfreq_list_lock);
+		if (!IS_ERR(devfreq)) {
+			dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
+			err = -EINVAL;
+			goto out;
+		}
+	}
+
+	devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
+	if (!devfreq) {
+		dev_err(dev, "%s: Unable to create devfreq for the device\n",
+			__func__);
+		err = -ENOMEM;
+		goto out;
+	}
+
+	mutex_init(&devfreq->lock);
+	mutex_lock(&devfreq->lock);
+	devfreq->dev.parent = dev;
+	devfreq->dev.class = devfreq_class;
+	devfreq->dev.release = devfreq_dev_release;
+	devfreq->profile = profile;
+	devfreq->governor = governor;
+	devfreq->previous_freq = profile->initial_freq;
+	devfreq->data = data;
+	devfreq->next_polling = devfreq->polling_jiffies
+			      = msecs_to_jiffies(devfreq->profile->polling_ms);
+	devfreq->nb.notifier_call = devfreq_notifier_call;
+
+	dev_set_name(&devfreq->dev, dev_name(dev));
+	err = device_register(&devfreq->dev);
+	if (err) {
+		put_device(&devfreq->dev);
+		goto err_dev;
+	}
+
+	if (governor->init)
+		err = governor->init(devfreq);
+	if (err)
+		goto err_init;
+
+	mutex_unlock(&devfreq->lock);
+
+	if (governor->no_central_polling)
+		goto out;
+
+	mutex_lock(&devfreq_list_lock);
+
+	list_add(&devfreq->node, &devfreq_list);
+
+	if (devfreq_wq && devfreq->next_polling && !polling) {
+		polling = true;
+		queue_delayed_work(devfreq_wq, &devfreq_work,
+				   devfreq->next_polling);
+	}
+	mutex_unlock(&devfreq_list_lock);
+	goto out;
+err_init:
+	device_unregister(&devfreq->dev);
+err_dev:
+	mutex_unlock(&devfreq->lock);
+	kfree(devfreq);
+out:
+	if (err)
+		return ERR_PTR(err);
+	else
+		return devfreq;
+}
+
+/**
+ * devfreq_remove_device() - Remove devfreq feature from a device.
+ * @devfreq	the devfreq instance to be removed
+ */
+int devfreq_remove_device(struct devfreq *devfreq)
+{
+	if (!devfreq)
+		return -EINVAL;
+
+	if (!devfreq->governor->no_central_polling) {
+		mutex_lock(&devfreq_list_lock);
+		while (wait_remove_device == devfreq) {
+			mutex_unlock(&devfreq_list_lock);
+			schedule();
+			mutex_lock(&devfreq_list_lock);
+		}
+	}
+
+	mutex_lock(&devfreq->lock);
+	_remove_devfreq(devfreq, false); /* it unlocks devfreq->lock */
+
+	if (!devfreq->governor->no_central_polling)
+		mutex_unlock(&devfreq_list_lock);
+
+	return 0;
+}
+
+/**
+ * devfreq_start_polling() - Initialize data structure for devfreq framework and
+ *			   start polling registered devfreq devices.
+ */
+static int __init devfreq_start_polling(void)
+{
+	mutex_lock(&devfreq_list_lock);
+	polling = false;
+	devfreq_wq = create_freezable_workqueue("devfreq_wq");
+	INIT_DELAYED_WORK_DEFERRABLE(&devfreq_work, devfreq_monitor);
+	mutex_unlock(&devfreq_list_lock);
+
+	devfreq_monitor(&devfreq_work.work);
+	return 0;
+}
+late_initcall(devfreq_start_polling);
+
+static int __init devfreq_init(void)
+{
+	devfreq_class = class_create(THIS_MODULE, "devfreq");
+	if (IS_ERR(devfreq_class)) {
+		pr_err("%s: couldn't create class\n", __FILE__);
+		return PTR_ERR(devfreq_class);
+	}
+	return 0;
+}
+subsys_initcall(devfreq_init);
+
+static void __exit devfreq_exit(void)
+{
+	class_destroy(devfreq_class);
+}
+module_exit(devfreq_exit);
+
+/*
+ * The followings are helper functions for devfreq user device drivers with
+ * OPP framework.
+ */
+
+/**
+ * devfreq_recommended_opp() - Helper function to get proper OPP for the
+ *			     freq value given to target callback.
+ * @dev		The devfreq user device. (parent of devfreq)
+ * @freq	The frequency given to target function
+ *
+ */
+struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq)
+{
+	struct opp *opp = opp_find_freq_ceil(dev, freq);
+
+	if (opp == ERR_PTR(-ENODEV))
+		opp = opp_find_freq_floor(dev, freq);
+	return opp;
+}
+
+/**
+ * devfreq_register_opp_notifier() - Helper function to get devfreq notified
+ *				   for any changes in the OPP availability
+ *				   changes
+ * @dev		The devfreq user device. (parent of devfreq)
+ * @devfreq	The devfreq object.
+ */
+int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
+{
+	struct srcu_notifier_head *nh = opp_get_notifier(dev);
+
+	if (IS_ERR(nh))
+		return PTR_ERR(nh);
+	return srcu_notifier_chain_register(nh, &devfreq->nb);
+}
+
+/**
+ * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
+ *				     notified for any changes in the OPP
+ *				     availability changes anymore.
+ * @dev		The devfreq user device. (parent of devfreq)
+ * @devfreq	The devfreq object.
+ *
+ * At exit() callback of devfreq_dev_profile, this must be included if
+ * devfreq_recommended_opp is used.
+ */
+int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
+{
+	struct srcu_notifier_head *nh = opp_get_notifier(dev);
+
+	if (IS_ERR(nh))
+		return PTR_ERR(nh);
+	return srcu_notifier_chain_unregister(nh, &devfreq->nb);
+}
+
+MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
+MODULE_DESCRIPTION("devfreq class support");
+MODULE_LICENSE("GPL");