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 <[email protected]>
 *
 * 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 {
    /* both since the last measure */
    unsigned long total_time;
    unsigned long busy_time;
    unsigned long current_frequency;
    void *private_data;
};

/*
 * The resulting frequency should be at most this. (this bound is the
 * least upper bound; thus, the resulting freq should be lower or same)
 * If the flag is not set, the resulting frequency should be at most the
 * bound (greatest lower bound)
 */
#define DEVFREQ_FLAG_LEAST_UPPER_BOUND      0x1

struct devfreq_dev_profile {
    unsigned long initial_freq;
    unsigned int polling_ms;

    int (*target)(struct device *dev, unsigned long *freq, u32 flags);
    int (*get_dev_status)(struct device *dev,
                  struct devfreq_dev_status *stat);
    void (*exit)(struct device *dev);
};

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 {
    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;

    unsigned long min_freq;
    unsigned long max_freq;
};

#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, u32 flags);
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 {
    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, u32 flags)
{
    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__ */