PM / devfreq: event: Add devfreq_event class

This patch adds a new class in devfreq, devfreq_event, which provides
raw data (e.g., memory bus utilization, GPU utilization) for devfreq
governors.

- devfreq_event device : Provides raw data for a governor of a devfreq device
- devfreq device       : Monitors device state and changes frequency/voltage
			of the device using the raw data from its
			devfreq_event device.

A devfreq device dertermines performance states (normally the frequency
and the voltage vlues) based on the results its designtated devfreq governor:
e.g., ondemand, performance, powersave.

In order to give such results required by a devfreq device, the devfreq
governor requires data that indicates the performance requirement given
to the devfreq device. The conventional (previous) implementatino of
devfreq subsystem requires a devfreq device driver to implement its own
mechanism to acquire performance requirement for its governor. However,
there had been issues with such requirements:

1. Although performance requirement of such devices is usually acquired
 from common devices (PMU/PPMU), we do not have any abstract structure to
 represent them properly.
2. Such performance requirement devices (PMU/PPMU) are actual hardware
 pieces that may be represented by Device Tree directly while devfreq device
 itself is a virtual entity that are not considered to be represented by
 Device Tree according to Device Tree folks.

In order to address such issues, a devferq_event device (represented by
this patch) provides a template for device drivers representing
performance monitoring unit, which gives the basic or raw data for
preformance requirement, which in turn, is required by devfreq governors.

The following description explains the feature of two kind of devfreq class:
- devfreq class (existing)
 : devfreq consumer device use raw data from devfreq_event device for
   determining proper current system state and change voltage/frequency
   dynamically using various governors.

- devfreq_event class (new)
 : Provide measured raw data to devfreq device for governor

Cc: MyungJoo Ham <myungjoo.ham@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
[Commit message rewritten & conflict resolved by MyungJoo]
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>

8 files changed, 1189 insertions, 0 deletions

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index 4aab799712bb..51dccb3620ea 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -97,4 +97,6 @@ config ARM_TEGRA_DEVFREQ
          It reads ACTMON counters of memory controllers and adjusts the
          operating frequencies and voltages with OPP support.
 
+source "drivers/devfreq/event/Kconfig"
+
 endif # PM_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 0ea991f3a483..9256c35bcce9 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -8,3 +8,6 @@ obj-$(CONFIG_DEVFREQ_GOV_USERSPACE)	+= governor_userspace.o
 obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ)	+= exynos/
 obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ)	+= exynos/
 obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
+
+# DEVFREQ Event Drivers
+obj-$(CONFIG_PM_DEVFREQ_EVENT)		+= event/
diff --git a/drivers/devfreq/devfreq-event.c b/drivers/devfreq/devfreq-event.c
new file mode 100644
index 000000000000..f304a0289eda
--- /dev/null
+++ b/drivers/devfreq/devfreq-event.c
@@ -0,0 +1,494 @@
+/*
+ * devfreq-event: a framework to provide raw data and events of devfreq devices
+ *
+ * Copyright (C) 2015 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.
+ *
+ * This driver is based on drivers/devfreq/devfreq.c.
+ */
+
+#include <linux/devfreq-event.h>
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/of.h>
+
+static struct class *devfreq_event_class;
+
+/* The list of all devfreq event list */
+static LIST_HEAD(devfreq_event_list);
+static DEFINE_MUTEX(devfreq_event_list_lock);
+
+#define to_devfreq_event(DEV) container_of(DEV, struct devfreq_event_dev, dev)
+
+/**
+ * devfreq_event_enable_edev() - Enable the devfreq-event dev and increase
+ *				 the enable_count of devfreq-event dev.
+ * @edev	: the devfreq-event device
+ *
+ * Note that this function increase the enable_count and enable the
+ * devfreq-event device. The devfreq-event device should be enabled before
+ * using it by devfreq device.
+ */
+int devfreq_event_enable_edev(struct devfreq_event_dev *edev)
+{
+	int ret = 0;
+
+	if (!edev || !edev->desc)
+		return -EINVAL;
+
+	mutex_lock(&edev->lock);
+	if (edev->desc->ops && edev->desc->ops->enable
+			&& edev->enable_count == 0) {
+		ret = edev->desc->ops->enable(edev);
+		if (ret < 0)
+			goto err;
+	}
+	edev->enable_count++;
+err:
+	mutex_unlock(&edev->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_enable_edev);
+
+/**
+ * devfreq_event_disable_edev() - Disable the devfreq-event dev and decrease
+ *				  the enable_count of the devfreq-event dev.
+ * @edev	: the devfreq-event device
+ *
+ * Note that this function decrease the enable_count and disable the
+ * devfreq-event device. After the devfreq-event device is disabled,
+ * devfreq device can't use the devfreq-event device for get/set/reset
+ * operations.
+ */
+int devfreq_event_disable_edev(struct devfreq_event_dev *edev)
+{
+	int ret = 0;
+
+	if (!edev || !edev->desc)
+		return -EINVAL;
+
+	mutex_lock(&edev->lock);
+	if (edev->enable_count <= 0) {
+		dev_warn(&edev->dev, "unbalanced enable_count\n");
+		ret = -EIO;
+		goto err;
+	}
+
+	if (edev->desc->ops && edev->desc->ops->disable
+			&& edev->enable_count == 1) {
+		ret = edev->desc->ops->disable(edev);
+		if (ret < 0)
+			goto err;
+	}
+	edev->enable_count--;
+err:
+	mutex_unlock(&edev->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_disable_edev);
+
+/**
+ * devfreq_event_is_enabled() - Check whether devfreq-event dev is enabled or
+ *				not.
+ * @edev	: the devfreq-event device
+ *
+ * Note that this function check whether devfreq-event dev is enabled or not.
+ * If return true, the devfreq-event dev is enabeld. If return false, the
+ * devfreq-event dev is disabled.
+ */
+bool devfreq_event_is_enabled(struct devfreq_event_dev *edev)
+{
+	bool enabled = false;
+
+	if (!edev || !edev->desc)
+		return enabled;
+
+	mutex_lock(&edev->lock);
+
+	if (edev->enable_count > 0)
+		enabled = true;
+
+	mutex_unlock(&edev->lock);
+
+	return enabled;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_is_enabled);
+
+/**
+ * devfreq_event_set_event() - Set event to devfreq-event dev to start.
+ * @edev	: the devfreq-event device
+ *
+ * Note that this function set the event to the devfreq-event device to start
+ * for getting the event data which could be various event type.
+ */
+int devfreq_event_set_event(struct devfreq_event_dev *edev)
+{
+	int ret;
+
+	if (!edev || !edev->desc)
+		return -EINVAL;
+
+	if (!edev->desc->ops || !edev->desc->ops->set_event)
+		return -EINVAL;
+
+	if (!devfreq_event_is_enabled(edev))
+		return -EPERM;
+
+	mutex_lock(&edev->lock);
+	ret = edev->desc->ops->set_event(edev);
+	mutex_unlock(&edev->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_set_event);
+
+/**
+ * devfreq_event_get_event() - Get {load|total}_count from devfreq-event dev.
+ * @edev	: the devfreq-event device
+ * @edata	: the calculated data of devfreq-event device
+ *
+ * Note that this function get the calculated event data from devfreq-event dev
+ * after stoping the progress of whole sequence of devfreq-event dev.
+ */
+int devfreq_event_get_event(struct devfreq_event_dev *edev,
+			    struct devfreq_event_data *edata)
+{
+	int ret;
+
+	if (!edev || !edev->desc)
+		return -EINVAL;
+
+	if (!edev->desc->ops || !edev->desc->ops->get_event)
+		return -EINVAL;
+
+	if (!devfreq_event_is_enabled(edev))
+		return -EINVAL;
+
+	edata->total_count = edata->load_count = 0;
+
+	mutex_lock(&edev->lock);
+	ret = edev->desc->ops->get_event(edev, edata);
+	if (ret < 0)
+		edata->total_count = edata->load_count = 0;
+	mutex_unlock(&edev->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_get_event);
+
+/**
+ * devfreq_event_reset_event() - Reset all opeations of devfreq-event dev.
+ * @edev	: the devfreq-event device
+ *
+ * Note that this function stop all operations of devfreq-event dev and reset
+ * the current event data to make the devfreq-event device into initial state.
+ */
+int devfreq_event_reset_event(struct devfreq_event_dev *edev)
+{
+	int ret = 0;
+
+	if (!edev || !edev->desc)
+		return -EINVAL;
+
+	if (!devfreq_event_is_enabled(edev))
+		return -EPERM;
+
+	mutex_lock(&edev->lock);
+	if (edev->desc->ops && edev->desc->ops->reset)
+		ret = edev->desc->ops->reset(edev);
+	mutex_unlock(&edev->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_reset_event);
+
+/**
+ * devfreq_event_get_edev_by_phandle() - Get the devfreq-event dev from
+ *					 devicetree.
+ * @dev		: the pointer to the given device
+ * @index	: the index into list of devfreq-event device
+ *
+ * Note that this function return the pointer of devfreq-event device.
+ */
+struct devfreq_event_dev *devfreq_event_get_edev_by_phandle(struct device *dev,
+						      int index)
+{
+	struct device_node *node;
+	struct devfreq_event_dev *edev;
+
+	if (!dev->of_node) {
+		dev_err(dev, "device does not have a device node entry\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	node = of_parse_phandle(dev->of_node, "devfreq-events", index);
+	if (!node) {
+		dev_err(dev, "failed to get phandle in %s node\n",
+			dev->of_node->full_name);
+		return ERR_PTR(-ENODEV);
+	}
+
+	mutex_lock(&devfreq_event_list_lock);
+	list_for_each_entry(edev, &devfreq_event_list, node) {
+		if (!strcmp(edev->desc->name, node->name))
+			goto out;
+	}
+	edev = NULL;
+out:
+	mutex_unlock(&devfreq_event_list_lock);
+
+	if (!edev) {
+		dev_err(dev, "unable to get devfreq-event device : %s\n",
+			node->name);
+		of_node_put(node);
+		return ERR_PTR(-ENODEV);
+	}
+
+	of_node_put(node);
+
+	return edev;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_get_edev_by_phandle);
+
+/**
+ * devfreq_event_get_edev_count() - Get the count of devfreq-event dev
+ * @dev		: the pointer to the given device
+ *
+ * Note that this function return the count of devfreq-event devices.
+ */
+int devfreq_event_get_edev_count(struct device *dev)
+{
+	int count;
+
+	if (!dev->of_node) {
+		dev_err(dev, "device does not have a device node entry\n");
+		return -EINVAL;
+	}
+
+	count = of_property_count_elems_of_size(dev->of_node, "devfreq-events",
+						sizeof(u32));
+	if (count < 0 ) {
+		dev_err(dev,
+			"failed to get the count of devfreq-event in %s node\n",
+			dev->of_node->full_name);
+		return count;
+	}
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_get_edev_count);
+
+static void devfreq_event_release_edev(struct device *dev)
+{
+	struct devfreq_event_dev *edev = to_devfreq_event(dev);
+
+	kfree(edev);
+}
+
+/**
+ * devfreq_event_add_edev() - Add new devfreq-event device.
+ * @dev		: the device owning the devfreq-event device being created
+ * @desc	: the devfreq-event device's decriptor which include essential
+ *		  data for devfreq-event device.
+ *
+ * Note that this function add new devfreq-event device to devfreq-event class
+ * list and register the device of the devfreq-event device.
+ */
+struct devfreq_event_dev *devfreq_event_add_edev(struct device *dev,
+						struct devfreq_event_desc *desc)
+{
+	struct devfreq_event_dev *edev;
+	static atomic_t event_no = ATOMIC_INIT(0);
+	int ret;
+
+	if (!dev || !desc)
+		return ERR_PTR(-EINVAL);
+
+	if (!desc->name || !desc->ops)
+		return ERR_PTR(-EINVAL);
+
+	if (!desc->ops->set_event || !desc->ops->get_event)
+		return ERR_PTR(-EINVAL);
+
+	edev = kzalloc(sizeof(struct devfreq_event_dev), GFP_KERNEL);
+	if (!edev)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&edev->lock);
+	edev->desc = desc;
+	edev->enable_count = 0;
+	edev->dev.parent = dev;
+	edev->dev.class = devfreq_event_class;
+	edev->dev.release = devfreq_event_release_edev;
+
+	dev_set_name(&edev->dev, "event.%d", atomic_inc_return(&event_no) - 1);
+	ret = device_register(&edev->dev);
+	if (ret < 0) {
+		put_device(&edev->dev);
+		return ERR_PTR(ret);
+	}
+	dev_set_drvdata(&edev->dev, edev);
+
+	INIT_LIST_HEAD(&edev->node);
+
+	mutex_lock(&devfreq_event_list_lock);
+	list_add(&edev->node, &devfreq_event_list);
+	mutex_unlock(&devfreq_event_list_lock);
+
+	return edev;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_add_edev);
+
+/**
+ * devfreq_event_remove_edev() - Remove the devfreq-event device registered.
+ * @dev		: the devfreq-event device
+ *
+ * Note that this function remove the registered devfreq-event device.
+ */
+int devfreq_event_remove_edev(struct devfreq_event_dev *edev)
+{
+	if (!edev)
+		return -EINVAL;
+
+	WARN_ON(edev->enable_count);
+
+	mutex_lock(&devfreq_event_list_lock);
+	list_del(&edev->node);
+	mutex_unlock(&devfreq_event_list_lock);
+
+	device_unregister(&edev->dev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(devfreq_event_remove_edev);
+
+static int devm_devfreq_event_match(struct device *dev, void *res, void *data)
+{
+	struct devfreq_event_dev **r = res;
+
+	if (WARN_ON(!r || !*r))
+		return 0;
+
+	return *r == data;
+}
+
+static void devm_devfreq_event_release(struct device *dev, void *res)
+{
+	devfreq_event_remove_edev(*(struct devfreq_event_dev **)res);
+}
+
+/**
+ * devm_devfreq_event_add_edev() - Resource-managed devfreq_event_add_edev()
+ * @dev		: the device owning the devfreq-event device being created
+ * @desc	: the devfreq-event device's decriptor which include essential
+ *		  data for devfreq-event device.
+ *
+ * Note that this function manages automatically the memory of devfreq-event
+ * device using device resource management and simplify the free operation
+ * for memory of devfreq-event device.
+ */
+struct devfreq_event_dev *devm_devfreq_event_add_edev(struct device *dev,
+						struct devfreq_event_desc *desc)
+{
+	struct devfreq_event_dev **ptr, *edev;
+
+	ptr = devres_alloc(devm_devfreq_event_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	edev = devfreq_event_add_edev(dev, desc);
+	if (IS_ERR(edev)) {
+		devres_free(ptr);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	*ptr = edev;
+	devres_add(dev, ptr);
+
+	return edev;
+}
+EXPORT_SYMBOL_GPL(devm_devfreq_event_add_edev);
+
+/**
+ * devm_devfreq_event_remove_edev()- Resource-managed devfreq_event_remove_edev()
+ * @dev		: the device owning the devfreq-event device being created
+ * @edev	: the devfreq-event device
+ *
+ * Note that this function manages automatically the memory of devfreq-event
+ * device using device resource management.
+ */
+void devm_devfreq_event_remove_edev(struct device *dev,
+				struct devfreq_event_dev *edev)
+{
+	WARN_ON(devres_release(dev, devm_devfreq_event_release,
+			       devm_devfreq_event_match, edev));
+}
+EXPORT_SYMBOL_GPL(devm_devfreq_event_remove_edev);
+
+/*
+ * Device attributes for devfreq-event class.
+ */
+static ssize_t name_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct devfreq_event_dev *edev = to_devfreq_event(dev);
+
+	if (!edev || !edev->desc)
+		return -EINVAL;
+
+	return sprintf(buf, "%s\n", edev->desc->name);
+}
+static DEVICE_ATTR_RO(name);
+
+static ssize_t enable_count_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct devfreq_event_dev *edev = to_devfreq_event(dev);
+
+	if (!edev || !edev->desc)
+		return -EINVAL;
+
+	return sprintf(buf, "%d\n", edev->enable_count);
+}
+static DEVICE_ATTR_RO(enable_count);
+
+static struct attribute *devfreq_event_attrs[] = {
+	&dev_attr_name.attr,
+	&dev_attr_enable_count.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(devfreq_event);
+
+static int __init devfreq_event_init(void)
+{
+	devfreq_event_class = class_create(THIS_MODULE, "devfreq-event");
+	if (IS_ERR(devfreq_event_class)) {
+		pr_err("%s: couldn't create class\n", __FILE__);
+		return PTR_ERR(devfreq_event_class);
+	}
+
+	devfreq_event_class->dev_groups = devfreq_event_groups;
+
+	return 0;
+}
+subsys_initcall(devfreq_event_init);
+
+static void __exit devfreq_event_exit(void)
+{
+	class_destroy(devfreq_event_class);
+}
+module_exit(devfreq_event_exit);
+
+MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
+MODULE_DESCRIPTION("DEVFREQ-Event class support");
+MODULE_LICENSE("GPL");
diff --git a/drivers/devfreq/event/Kconfig b/drivers/devfreq/event/Kconfig
new file mode 100644
index 000000000000..a11720affc31
--- /dev/null
+++ b/drivers/devfreq/event/Kconfig
@@ -0,0 +1,25 @@
+menuconfig PM_DEVFREQ_EVENT
+	bool "DEVFREQ-Event device Support"
+	help
+	  The devfreq-event device provide the raw data and events which
+	  indicate the current state of devfreq-event device. The provided
+	  data from devfreq-event device is used to monitor the state of
+	  device and determine the suitable size of resource to reduce the
+	  wasted resource.
+
+	  The devfreq-event device can support the various type of events
+	  (e.g., raw data, utilization, latency, bandwidth). The events
+	  may be used by devfreq governor and other subsystem.
+
+if PM_DEVFREQ_EVENT
+
+config DEVFREQ_EVENT_EXYNOS_PPMU
+	bool "EXYNOS PPMU (Platform Performance Monitoring Unit) DEVFREQ event Driver"
+	depends on ARCH_EXYNOS
+	select PM_OPP
+	help
+	  This add the devfreq-event driver for Exynos SoC. It provides PPMU
+	  (Platform Performance Monitoring Unit) counters to estimate the
+	  utilization of each module.
+
+endif # PM_DEVFREQ_EVENT
diff --git a/drivers/devfreq/event/Makefile b/drivers/devfreq/event/Makefile
new file mode 100644
index 000000000000..be146ead79cf
--- /dev/null
+++ b/drivers/devfreq/event/Makefile
@@ -0,0 +1,2 @@
+# Exynos DEVFREQ Event Drivers
+obj-$(CONFIG_DEVFREQ_EVENT_EXYNOS_PPMU) += exynos-ppmu.o
diff --git a/drivers/devfreq/event/exynos-ppmu.c b/drivers/devfreq/event/exynos-ppmu.c
new file mode 100644
index 000000000000..135be0aada9d
--- /dev/null
+++ b/drivers/devfreq/event/exynos-ppmu.c
@@ -0,0 +1,374 @@
+/*
+ * exynos_ppmu.c - EXYNOS PPMU (Platform Performance Monitoring Unit) support
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * 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.
+ *
+ * This driver is based on drivers/devfreq/exynos/exynos_ppmu.c
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/suspend.h>
+#include <linux/devfreq-event.h>
+
+#include "exynos-ppmu.h"
+
+struct exynos_ppmu_data {
+	void __iomem *base;
+	struct clk *clk;
+};
+
+struct exynos_ppmu {
+	struct devfreq_event_dev **edev;
+	struct devfreq_event_desc *desc;
+	unsigned int num_events;
+
+	struct device *dev;
+	struct mutex lock;
+
+	struct exynos_ppmu_data ppmu;
+};
+
+#define PPMU_EVENT(name)			\
+	{ "ppmu-event0-"#name, PPMU_PMNCNT0 },	\
+	{ "ppmu-event1-"#name, PPMU_PMNCNT1 },	\
+	{ "ppmu-event2-"#name, PPMU_PMNCNT2 },	\
+	{ "ppmu-event3-"#name, PPMU_PMNCNT3 }
+
+struct __exynos_ppmu_events {
+	char *name;
+	int id;
+} ppmu_events[] = {
+	/* For Exynos3250, Exynos4 and Exynos5260 */
+	PPMU_EVENT(g3d),
+	PPMU_EVENT(fsys),
+
+	/* For Exynos4 SoCs and Exynos3250 */
+	PPMU_EVENT(dmc0),
+	PPMU_EVENT(dmc1),
+	PPMU_EVENT(cpu),
+	PPMU_EVENT(rightbus),
+	PPMU_EVENT(leftbus),
+	PPMU_EVENT(lcd0),
+	PPMU_EVENT(camif),
+
+	/* Only for Exynos3250 and Exynos5260 */
+	PPMU_EVENT(mfc),
+
+	/* Only for Exynos4 SoCs */
+	PPMU_EVENT(mfc-left),
+	PPMU_EVENT(mfc-right),
+
+	/* Only for Exynos5260 SoCs */
+	PPMU_EVENT(drex0-s0),
+	PPMU_EVENT(drex0-s1),
+	PPMU_EVENT(drex1-s0),
+	PPMU_EVENT(drex1-s1),
+	PPMU_EVENT(eagle),
+	PPMU_EVENT(kfc),
+	PPMU_EVENT(isp),
+	PPMU_EVENT(fimc),
+	PPMU_EVENT(gscl),
+	PPMU_EVENT(mscl),
+	PPMU_EVENT(fimd0x),
+	PPMU_EVENT(fimd1x),
+	{ /* sentinel */ },
+};
+
+static int exynos_ppmu_find_ppmu_id(struct devfreq_event_dev *edev)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ppmu_events); i++)
+		if (!strcmp(edev->desc->name, ppmu_events[i].name))
+			return ppmu_events[i].id;
+
+	return -EINVAL;
+}
+
+static int exynos_ppmu_disable(struct devfreq_event_dev *edev)
+{
+	struct exynos_ppmu *info = devfreq_event_get_drvdata(edev);
+	u32 pmnc;
+
+	/* Disable all counters */
+	__raw_writel(PPMU_CCNT_MASK |
+		     PPMU_PMCNT0_MASK |
+		     PPMU_PMCNT1_MASK |
+		     PPMU_PMCNT2_MASK |
+		     PPMU_PMCNT3_MASK,
+		     info->ppmu.base + PPMU_CNTENC);
+
+	/* Disable PPMU */
+	pmnc = __raw_readl(info->ppmu.base + PPMU_PMNC);
+	pmnc &= ~PPMU_PMNC_ENABLE_MASK;
+	__raw_writel(pmnc, info->ppmu.base + PPMU_PMNC);
+
+	return 0;
+}
+
+static int exynos_ppmu_set_event(struct devfreq_event_dev *edev)
+{
+	struct exynos_ppmu *info = devfreq_event_get_drvdata(edev);
+	int id = exynos_ppmu_find_ppmu_id(edev);
+	u32 pmnc, cntens;
+
+	if (id < 0)
+		return id;
+
+	/* Enable specific counter */
+	cntens = __raw_readl(info->ppmu.base + PPMU_CNTENS);
+	cntens |= (PPMU_CCNT_MASK | (PPMU_ENABLE << id));
+	__raw_writel(cntens, info->ppmu.base + PPMU_CNTENS);
+
+	/* Set the event of Read/Write data count  */
+	__raw_writel(PPMU_RO_DATA_CNT | PPMU_WO_DATA_CNT,
+			info->ppmu.base + PPMU_BEVTxSEL(id));
+
+	/* Reset cycle counter/performance counter and enable PPMU */
+	pmnc = __raw_readl(info->ppmu.base + PPMU_PMNC);
+	pmnc &= ~(PPMU_PMNC_ENABLE_MASK
+			| PPMU_PMNC_COUNTER_RESET_MASK
+			| PPMU_PMNC_CC_RESET_MASK);
+	pmnc |= (PPMU_ENABLE << PPMU_PMNC_ENABLE_SHIFT);
+	pmnc |= (PPMU_ENABLE << PPMU_PMNC_COUNTER_RESET_SHIFT);
+	pmnc |= (PPMU_ENABLE << PPMU_PMNC_CC_RESET_SHIFT);
+	__raw_writel(pmnc, info->ppmu.base + PPMU_PMNC);
+
+	return 0;
+}
+
+static int exynos_ppmu_get_event(struct devfreq_event_dev *edev,
+				struct devfreq_event_data *edata)
+{
+	struct exynos_ppmu *info = devfreq_event_get_drvdata(edev);
+	int id = exynos_ppmu_find_ppmu_id(edev);
+	u32 pmnc, cntenc;
+
+	if (id < 0)
+		return -EINVAL;
+
+	/* Disable PPMU */
+	pmnc = __raw_readl(info->ppmu.base + PPMU_PMNC);
+	pmnc &= ~PPMU_PMNC_ENABLE_MASK;
+	__raw_writel(pmnc, info->ppmu.base + PPMU_PMNC);
+
+	/* Read cycle count */
+	edata->total_count = __raw_readl(info->ppmu.base + PPMU_CCNT);
+
+	/* Read performance count */
+	switch (id) {
+	case PPMU_PMNCNT0:
+	case PPMU_PMNCNT1:
+	case PPMU_PMNCNT2:
+		edata->load_count
+			= __raw_readl(info->ppmu.base + PPMU_PMNCT(id));
+		break;
+	case PPMU_PMNCNT3:
+		edata->load_count =
+			((__raw_readl(info->ppmu.base + PPMU_PMCNT3_HIGH) << 8)
+			| __raw_readl(info->ppmu.base + PPMU_PMCNT3_LOW));
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Disable specific counter */
+	cntenc = __raw_readl(info->ppmu.base + PPMU_CNTENC);
+	cntenc |= (PPMU_CCNT_MASK | (PPMU_ENABLE << id));
+	__raw_writel(cntenc, info->ppmu.base + PPMU_CNTENC);
+
+	dev_dbg(&edev->dev, "%s (event: %ld/%ld)\n", edev->desc->name,
+					edata->load_count, edata->total_count);
+
+	return 0;
+}
+
+static struct devfreq_event_ops exynos_ppmu_ops = {
+	.disable = exynos_ppmu_disable,
+	.set_event = exynos_ppmu_set_event,
+	.get_event = exynos_ppmu_get_event,
+};
+
+static int of_get_devfreq_events(struct device_node *np,
+				 struct exynos_ppmu *info)
+{
+	struct devfreq_event_desc *desc;
+	struct device *dev = info->dev;
+	struct device_node *events_np, *node;
+	int i, j, count;
+
+	events_np = of_get_child_by_name(np, "events");
+	if (!events_np) {
+		dev_err(dev,
+			"failed to get child node of devfreq-event devices\n");
+		return -EINVAL;
+	}
+
+	count = of_get_child_count(events_np);
+	desc = devm_kzalloc(dev, sizeof(*desc) * count, GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+	info->num_events = count;
+
+	j = 0;
+	for_each_child_of_node(events_np, node) {
+		for (i = 0; i < ARRAY_SIZE(ppmu_events); i++) {
+			if (!ppmu_events[i].name)
+				continue;
+
+			if (!of_node_cmp(node->name, ppmu_events[i].name))
+				break;
+		}
+
+		if (i == ARRAY_SIZE(ppmu_events)) {
+			dev_warn(dev,
+				"don't know how to configure events : %s\n",
+				node->name);
+			continue;
+		}
+
+		desc[j].ops = &exynos_ppmu_ops;
+		desc[j].driver_data = info;
+
+		of_property_read_string(node, "event-name", &desc[j].name);
+
+		j++;
+
+		of_node_put(node);
+	}
+	info->desc = desc;
+
+	of_node_put(events_np);
+
+	return 0;
+}
+
+static int exynos_ppmu_parse_dt(struct exynos_ppmu *info)
+{
+	struct device *dev = info->dev;
+	struct device_node *np = dev->of_node;
+	int ret = 0;
+
+	if (!np) {
+		dev_err(dev, "failed to find devicetree node\n");
+		return -EINVAL;
+	}
+
+	/* Maps the memory mapped IO to control PPMU register */
+	info->ppmu.base = of_iomap(np, 0);
+	if (IS_ERR_OR_NULL(info->ppmu.base)) {
+		dev_err(dev, "failed to map memory region\n");
+		return -ENOMEM;
+	}
+
+	info->ppmu.clk = devm_clk_get(dev, "ppmu");
+	if (IS_ERR(info->ppmu.clk)) {
+		info->ppmu.clk = NULL;
+		dev_warn(dev, "cannot get PPMU clock\n");
+	}
+
+	ret = of_get_devfreq_events(np, info);
+	if (ret < 0) {
+		dev_err(dev, "failed to parse exynos ppmu dt node\n");
+		goto err;
+	}
+
+	return 0;
+
+err:
+	iounmap(info->ppmu.base);
+
+	return ret;
+}
+
+static int exynos_ppmu_probe(struct platform_device *pdev)
+{
+	struct exynos_ppmu *info;
+	struct devfreq_event_dev **edev;
+	struct devfreq_event_desc *desc;
+	int i, ret = 0, size;
+
+	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	mutex_init(&info->lock);
+	info->dev = &pdev->dev;
+
+	/* Parse dt data to get resource */
+	ret = exynos_ppmu_parse_dt(info);
+	if (ret < 0) {
+		dev_err(&pdev->dev,
+			"failed to parse devicetree for resource\n");
+		return ret;
+	}
+	desc = info->desc;
+
+	size = sizeof(struct devfreq_event_dev *) * info->num_events;
+	info->edev = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
+	if (!info->edev) {
+		dev_err(&pdev->dev,
+			"failed to allocate memory devfreq-event devices\n");
+		return -ENOMEM;
+	}
+	edev = info->edev;
+	platform_set_drvdata(pdev, info);
+
+	for (i = 0; i < info->num_events; i++) {
+		edev[i] = devm_devfreq_event_add_edev(&pdev->dev, &desc[i]);
+		if (IS_ERR(edev)) {
+			ret = PTR_ERR(edev);
+			dev_err(&pdev->dev,
+				"failed to add devfreq-event device\n");
+			goto err;
+		}
+	}
+
+	clk_prepare_enable(info->ppmu.clk);
+
+	return 0;
+err:
+	iounmap(info->ppmu.base);
+
+	return ret;
+}
+
+static int exynos_ppmu_remove(struct platform_device *pdev)
+{
+	struct exynos_ppmu *info = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(info->ppmu.clk);
+	iounmap(info->ppmu.base);
+
+	return 0;
+}
+
+static struct of_device_id exynos_ppmu_id_match[] = {
+	{ .compatible = "samsung,exynos-ppmu", },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver exynos_ppmu_driver = {
+	.probe	= exynos_ppmu_probe,
+	.remove	= exynos_ppmu_remove,
+	.driver = {
+		.name	= "exynos-ppmu",
+		.of_match_table = exynos_ppmu_id_match,
+	},
+};
+module_platform_driver(exynos_ppmu_driver);
+
+MODULE_DESCRIPTION("Exynos PPMU(Platform Performance Monitoring Unit) driver");
+MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/devfreq/event/exynos-ppmu.h b/drivers/devfreq/event/exynos-ppmu.h
new file mode 100644
index 000000000000..4e831d48c138
--- /dev/null
+++ b/drivers/devfreq/event/exynos-ppmu.h
@@ -0,0 +1,93 @@
+/*
+ * exynos_ppmu.h - EXYNOS PPMU header file
+ *
+ * Copyright (c) 2015 Samsung Electronics Co., Ltd.
+ * 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 __EXYNOS_PPMU_H__
+#define __EXYNOS_PPMU_H__
+
+enum ppmu_state {
+	PPMU_DISABLE = 0,
+	PPMU_ENABLE,
+};
+
+enum ppmu_counter {
+	PPMU_PMNCNT0 = 0,
+	PPMU_PMNCNT1,
+	PPMU_PMNCNT2,
+	PPMU_PMNCNT3,
+
+	PPMU_PMNCNT_MAX,
+};
+
+enum ppmu_event_type {
+	PPMU_RO_BUSY_CYCLE_CNT	= 0x0,
+	PPMU_WO_BUSY_CYCLE_CNT	= 0x1,
+	PPMU_RW_BUSY_CYCLE_CNT	= 0x2,
+	PPMU_RO_REQUEST_CNT	= 0x3,
+	PPMU_WO_REQUEST_CNT	= 0x4,
+	PPMU_RO_DATA_CNT	= 0x5,
+	PPMU_WO_DATA_CNT	= 0x6,
+	PPMU_RO_LATENCY		= 0x12,
+	PPMU_WO_LATENCY		= 0x16,
+};
+
+enum ppmu_reg {
+	/* PPC control register */
+	PPMU_PMNC		= 0x00,
+	PPMU_CNTENS		= 0x10,
+	PPMU_CNTENC		= 0x20,
+	PPMU_INTENS		= 0x30,
+	PPMU_INTENC		= 0x40,
+	PPMU_FLAG		= 0x50,
+
+	/* Cycle Counter and Performance Event Counter Register */
+	PPMU_CCNT		= 0x100,
+	PPMU_PMCNT0		= 0x110,
+	PPMU_PMCNT1		= 0x120,
+	PPMU_PMCNT2		= 0x130,
+	PPMU_PMCNT3_HIGH	= 0x140,
+	PPMU_PMCNT3_LOW		= 0x150,
+
+	/* Bus Event Generator */
+	PPMU_BEVT0SEL		= 0x1000,
+	PPMU_BEVT1SEL		= 0x1100,
+	PPMU_BEVT2SEL		= 0x1200,
+	PPMU_BEVT3SEL		= 0x1300,
+	PPMU_COUNTER_RESET	= 0x1810,
+	PPMU_READ_OVERFLOW_CNT	= 0x1810,
+	PPMU_READ_UNDERFLOW_CNT	= 0x1814,
+	PPMU_WRITE_OVERFLOW_CNT	= 0x1850,
+	PPMU_WRITE_UNDERFLOW_CNT = 0x1854,
+	PPMU_READ_PENDING_CNT	= 0x1880,
+	PPMU_WRITE_PENDING_CNT	= 0x1884
+};
+
+/* PMNC register */
+#define PPMU_PMNC_CC_RESET_SHIFT	2
+#define PPMU_PMNC_COUNTER_RESET_SHIFT	1
+#define PPMU_PMNC_ENABLE_SHIFT		0
+#define PPMU_PMNC_START_MODE_MASK	BIT(16)
+#define PPMU_PMNC_CC_DIVIDER_MASK	BIT(3)
+#define PPMU_PMNC_CC_RESET_MASK		BIT(2)
+#define PPMU_PMNC_COUNTER_RESET_MASK	BIT(1)
+#define PPMU_PMNC_ENABLE_MASK		BIT(0)
+
+/* CNTENS/CNTENC/INTENS/INTENC/FLAG register */
+#define PPMU_CCNT_MASK			BIT(31)
+#define PPMU_PMCNT3_MASK		BIT(3)
+#define PPMU_PMCNT2_MASK		BIT(2)
+#define PPMU_PMCNT1_MASK		BIT(1)
+#define PPMU_PMCNT0_MASK		BIT(0)
+
+/* PPMU_PMNCTx/PPMU_BETxSEL registers */
+#define PPMU_PMNCT(x)			(PPMU_PMCNT0 + (0x10 * x))
+#define PPMU_BEVTxSEL(x)		(PPMU_BEVT0SEL + (0x100 * x))
+
+#endif /* __EXYNOS_PPMU_H__ */
diff --git a/include/linux/devfreq-event.h b/include/linux/devfreq-event.h
new file mode 100644
index 000000000000..602fbbfcfeed
--- /dev/null
+++ b/include/linux/devfreq-event.h
@@ -0,0 +1,196 @@
+/*
+ * 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;
+
+	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 void *devfreq_event_get_drvdata(struct devfreq_event_dev *edev)
+{
+	return ERR_PTR(-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__ */