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diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
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+/*
+ * 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.
+ */
+
+#ifndef __LINUX_DEVFREQ_H__
+#define __LINUX_DEVFREQ_H__
+
+#include <linux/device.h>
+#include <linux/notifier.h>
+#include <linux/opp.h>
+
+#define DEVFREQ_NAME_LEN 16
+
+struct devfreq;
+
+/**
+ * struct devfreq_dev_status - Data given from devfreq user device to
+ * governors. Represents the performance
+ * statistics.
+ * @total_time The total time represented by this instance of
+ * devfreq_dev_status
+ * @busy_time The time that the device was working among the
+ * total_time.
+ * @current_frequency The operating frequency.
+ * @private_data An entry not specified by the devfreq framework.
+ * A device and a specific governor may have their
+ * own protocol with private_data. However, because
+ * this is governor-specific, a governor using this
+ * will be only compatible with devices aware of it.
+ */
+struct devfreq_dev_status {
+ /* both since the last measure */
+ unsigned long total_time;
+ unsigned long busy_time;
+ unsigned long current_frequency;
+ void *private_date;
+};
+
+/**
+ * struct devfreq_dev_profile - Devfreq's user device profile
+ * @initial_freq The operating frequency when devfreq_add_device() is
+ * called.
+ * @polling_ms The polling interval in ms. 0 disables polling.
+ * @target The device should set its operating frequency at
+ * freq or lowest-upper-than-freq value. If freq is
+ * higher than any operable frequency, set maximum.
+ * Before returning, target function should set
+ * freq at the current frequency.
+ * @get_dev_status The device should provide the current performance
+ * status to devfreq, which is used by governors.
+ * @exit An optional callback that is called when devfreq
+ * is removing the devfreq object due to error or
+ * from devfreq_remove_device() call. If the user
+ * has registered devfreq->nb at a notifier-head,
+ * this is the time to unregister it.
+ */
+struct devfreq_dev_profile {
+ unsigned long initial_freq;
+ unsigned int polling_ms;
+
+ int (*target)(struct device *dev, unsigned long *freq);
+ int (*get_dev_status)(struct device *dev,
+ struct devfreq_dev_status *stat);
+ void (*exit)(struct device *dev);
+};
+
+/**
+ * struct devfreq_governor - Devfreq policy governor
+ * @name Governor's name
+ * @get_target_freq Returns desired operating frequency for the device.
+ * Basically, get_target_freq will run
+ * devfreq_dev_profile.get_dev_status() to get the
+ * status of the device (load = busy_time / total_time).
+ * If no_central_polling is set, this callback is called
+ * only with update_devfreq() notified by OPP.
+ * @init Called when the devfreq is being attached to a device
+ * @exit Called when the devfreq is being removed from a
+ * device. Governor should stop any internal routines
+ * before return because related data may be
+ * freed after exit().
+ * @no_central_polling Do not use devfreq's central polling mechanism.
+ * When this is set, devfreq will not call
+ * get_target_freq with devfreq_monitor(). However,
+ * devfreq will call get_target_freq with
+ * devfreq_update() notified by OPP framework.
+ *
+ * Note that the callbacks are called with devfreq->lock locked by devfreq.
+ */
+struct devfreq_governor {
+ const char name[DEVFREQ_NAME_LEN];
+ int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
+ int (*init)(struct devfreq *this);
+ void (*exit)(struct devfreq *this);
+ const bool no_central_polling;
+};
+
+/**
+ * struct devfreq - Device devfreq structure
+ * @node list node - contains the devices with devfreq that have been
+ * registered.
+ * @lock a mutex to protect accessing devfreq.
+ * @dev device registered by devfreq class. dev.parent is the device
+ * using devfreq.
+ * @profile device-specific devfreq profile
+ * @governor method how to choose frequency based on the usage.
+ * @nb notifier block used to notify devfreq object that it should
+ * reevaluate operable frequencies. Devfreq users may use
+ * devfreq.nb to the corresponding register notifier call chain.
+ * @polling_jiffies interval in jiffies.
+ * @previous_freq previously configured frequency value.
+ * @next_polling the number of remaining jiffies to poll with
+ * "devfreq_monitor" executions to reevaluate
+ * frequency/voltage of the device. Set by
+ * profile's polling_ms interval.
+ * @data Private data of the governor. The devfreq framework does not
+ * touch this.
+ * @being_removed a flag to mark that this object is being removed in
+ * order to prevent trying to remove the object multiple times.
+ *
+ * This structure stores the devfreq information for a give device.
+ *
+ * Note that when a governor accesses entries in struct devfreq in its
+ * functions except for the context of callbacks defined in struct
+ * devfreq_governor, the governor should protect its access with the
+ * struct mutex lock in struct devfreq. A governor may use this mutex
+ * to protect its own private data in void *data as well.
+ */
+struct devfreq {
+ struct list_head node;
+
+ struct mutex lock;
+ struct device dev;
+ struct devfreq_dev_profile *profile;
+ const struct devfreq_governor *governor;
+ struct notifier_block nb;
+
+ unsigned long polling_jiffies;
+ unsigned long previous_freq;
+ unsigned int next_polling;
+
+ void *data; /* private data for governors */
+
+ bool being_removed;
+};
+
+#if defined(CONFIG_PM_DEVFREQ)
+extern struct devfreq *devfreq_add_device(struct device *dev,
+ struct devfreq_dev_profile *profile,
+ const struct devfreq_governor *governor,
+ void *data);
+extern int devfreq_remove_device(struct devfreq *devfreq);
+
+/* Helper functions for devfreq user device driver with OPP. */
+extern struct opp *devfreq_recommended_opp(struct device *dev,
+ unsigned long *freq);
+extern int devfreq_register_opp_notifier(struct device *dev,
+ struct devfreq *devfreq);
+extern int devfreq_unregister_opp_notifier(struct device *dev,
+ struct devfreq *devfreq);
+
+#ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
+extern const struct devfreq_governor devfreq_powersave;
+#endif
+#ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
+extern const struct devfreq_governor devfreq_performance;
+#endif
+#ifdef CONFIG_DEVFREQ_GOV_USERSPACE
+extern const struct devfreq_governor devfreq_userspace;
+#endif
+#ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
+extern const struct devfreq_governor devfreq_simple_ondemand;
+/**
+ * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
+ * and devfreq_add_device
+ * @ upthreshold If the load is over this value, the frequency jumps.
+ * Specify 0 to use the default. Valid value = 0 to 100.
+ * @ downdifferential If the load is under upthreshold - downdifferential,
+ * the governor may consider slowing the frequency down.
+ * Specify 0 to use the default. Valid value = 0 to 100.
+ * downdifferential < upthreshold must hold.
+ *
+ * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
+ * the governor uses the default values.
+ */
+struct devfreq_simple_ondemand_data {
+ unsigned int upthreshold;
+ unsigned int downdifferential;
+};
+#endif
+
+#else /* !CONFIG_PM_DEVFREQ */
+static struct devfreq *devfreq_add_device(struct device *dev,
+ struct devfreq_dev_profile *profile,
+ struct devfreq_governor *governor,
+ void *data);
+{
+ return NULL;
+}
+
+static int devfreq_remove_device(struct devfreq *devfreq);
+{
+ return 0;
+}
+
+static struct opp *devfreq_recommended_opp(struct device *dev,
+ unsigned long *freq)
+{
+ return -EINVAL;
+}
+
+static int devfreq_register_opp_notifier(struct device *dev,
+ struct devfreq *devfreq)
+{
+ return -EINVAL;
+}
+
+static int devfreq_unregister_opp_notifier(struct device *dev,
+ struct devfreq *devfreq)
+{
+ return -EINVAL;
+}
+
+#define devfreq_powersave NULL
+#define devfreq_performance NULL
+#define devfreq_userspace NULL
+#define devfreq_simple_ondemand NULL
+
+#endif /* CONFIG_PM_DEVFREQ */
+
+#endif /* __LINUX_DEVFREQ_H__ */