v4.19.13 snapshot.
diff --git a/include/linux/devfreq-event.h b/include/linux/devfreq-event.h
new file mode 100644
index 0000000..4db00b0
--- /dev/null
+++ b/include/linux/devfreq-event.h
@@ -0,0 +1,191 @@
+/*
+ * devfreq-event: a framework to provide raw data and events of devfreq devices
+ *
+ * Copyright (C) 2014 Samsung Electronics
+ * Author: Chanwoo Choi <cw00.choi@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.
+ */
+
+#ifndef __LINUX_DEVFREQ_EVENT_H__
+#define __LINUX_DEVFREQ_EVENT_H__
+
+#include <linux/device.h>
+
+/**
+ * struct devfreq_event_dev - the devfreq-event device
+ *
+ * @node	: Contain the devfreq-event device that have been registered.
+ * @dev		: the device registered by devfreq-event class. dev.parent is
+ *		  the device using devfreq-event.
+ * @lock	: a mutex to protect accessing devfreq-event.
+ * @enable_count: the number of enable function have been called.
+ * @desc	: the description for devfreq-event device.
+ *
+ * This structure contains devfreq-event device information.
+ */
+struct devfreq_event_dev {
+	struct list_head node;
+
+	struct device dev;
+	struct mutex lock;
+	u32 enable_count;
+
+	const struct devfreq_event_desc *desc;
+};
+
+/**
+ * struct devfreq_event_data - the devfreq-event data
+ *
+ * @load_count	: load count of devfreq-event device for the given period.
+ * @total_count	: total count of devfreq-event device for the given period.
+ *		  each count may represent a clock cycle, a time unit
+ *		  (ns/us/...), or anything the device driver wants.
+ *		  Generally, utilization is load_count / total_count.
+ *
+ * This structure contains the data of devfreq-event device for polling period.
+ */
+struct devfreq_event_data {
+	unsigned long load_count;
+	unsigned long total_count;
+};
+
+/**
+ * struct devfreq_event_ops - the operations of devfreq-event device
+ *
+ * @enable	: Enable the devfreq-event device.
+ * @disable	: Disable the devfreq-event device.
+ * @reset	: Reset all setting of the devfreq-event device.
+ * @set_event	: Set the specific event type for the devfreq-event device.
+ * @get_event	: Get the result of the devfreq-event devie with specific
+ *		  event type.
+ *
+ * This structure contains devfreq-event device operations which can be
+ * implemented by devfreq-event device drivers.
+ */
+struct devfreq_event_ops {
+	/* Optional functions */
+	int (*enable)(struct devfreq_event_dev *edev);
+	int (*disable)(struct devfreq_event_dev *edev);
+	int (*reset)(struct devfreq_event_dev *edev);
+
+	/* Mandatory functions */
+	int (*set_event)(struct devfreq_event_dev *edev);
+	int (*get_event)(struct devfreq_event_dev *edev,
+			 struct devfreq_event_data *edata);
+};
+
+/**
+ * struct devfreq_event_desc - the descriptor of devfreq-event device
+ *
+ * @name	: the name of devfreq-event device.
+ * @driver_data	: the private data for devfreq-event driver.
+ * @ops		: the operation to control devfreq-event device.
+ *
+ * Each devfreq-event device is described with a this structure.
+ * This structure contains the various data for devfreq-event device.
+ */
+struct devfreq_event_desc {
+	const char *name;
+	void *driver_data;
+
+	const struct devfreq_event_ops *ops;
+};
+
+#if defined(CONFIG_PM_DEVFREQ_EVENT)
+extern int devfreq_event_enable_edev(struct devfreq_event_dev *edev);
+extern int devfreq_event_disable_edev(struct devfreq_event_dev *edev);
+extern bool devfreq_event_is_enabled(struct devfreq_event_dev *edev);
+extern int devfreq_event_set_event(struct devfreq_event_dev *edev);
+extern int devfreq_event_get_event(struct devfreq_event_dev *edev,
+				struct devfreq_event_data *edata);
+extern int devfreq_event_reset_event(struct devfreq_event_dev *edev);
+extern struct devfreq_event_dev *devfreq_event_get_edev_by_phandle(
+				struct device *dev, int index);
+extern int devfreq_event_get_edev_count(struct device *dev);
+extern struct devfreq_event_dev *devfreq_event_add_edev(struct device *dev,
+				struct devfreq_event_desc *desc);
+extern int devfreq_event_remove_edev(struct devfreq_event_dev *edev);
+extern struct devfreq_event_dev *devm_devfreq_event_add_edev(struct device *dev,
+				struct devfreq_event_desc *desc);
+extern void devm_devfreq_event_remove_edev(struct device *dev,
+				struct devfreq_event_dev *edev);
+static inline void *devfreq_event_get_drvdata(struct devfreq_event_dev *edev)
+{
+	return edev->desc->driver_data;
+}
+#else
+static inline int devfreq_event_enable_edev(struct devfreq_event_dev *edev)
+{
+	return -EINVAL;
+}
+
+static inline int devfreq_event_disable_edev(struct devfreq_event_dev *edev)
+{
+	return -EINVAL;
+}
+
+static inline bool devfreq_event_is_enabled(struct devfreq_event_dev *edev)
+{
+	return false;
+}
+
+static inline int devfreq_event_set_event(struct devfreq_event_dev *edev)
+{
+	return -EINVAL;
+}
+
+static inline int devfreq_event_get_event(struct devfreq_event_dev *edev,
+					struct devfreq_event_data *edata)
+{
+	return -EINVAL;
+}
+
+static inline int devfreq_event_reset_event(struct devfreq_event_dev *edev)
+{
+	return -EINVAL;
+}
+
+static inline struct devfreq_event_dev *devfreq_event_get_edev_by_phandle(
+					struct device *dev, int index)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline int devfreq_event_get_edev_count(struct device *dev)
+{
+	return -EINVAL;
+}
+
+static inline struct devfreq_event_dev *devfreq_event_add_edev(struct device *dev,
+					struct devfreq_event_desc *desc)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline int devfreq_event_remove_edev(struct devfreq_event_dev *edev)
+{
+	return -EINVAL;
+}
+
+static inline struct devfreq_event_dev *devm_devfreq_event_add_edev(
+					struct device *dev,
+					struct devfreq_event_desc *desc)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline void devm_devfreq_event_remove_edev(struct device *dev,
+					struct devfreq_event_dev *edev)
+{
+}
+
+static inline void *devfreq_event_get_drvdata(struct devfreq_event_dev *edev)
+{
+	return NULL;
+}
+#endif /* CONFIG_PM_DEVFREQ_EVENT */
+
+#endif /* __LINUX_DEVFREQ_EVENT_H__ */