/*
 * 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/pm_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_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 - 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.
 *                      The "flags" parameter's possible values are
 *                      explained above with "DEVFREQ_FLAG_*" macros.
 * @get_dev_status:     The device should provide the current performance
 *                      status to devfreq, which is used by governors.
 * @get_cur_freq:       The device should provide the current frequency
 *                      at which it is operating.
 * @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.
 * @freq_table: Optional list of frequencies to support statistics.
 * @max_state:  The size of freq_table.
 */
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);
        int (*get_cur_freq)(struct device *dev, unsigned long *freq);
        void (*exit)(struct device *dev);

        unsigned int *freq_table;
        unsigned int max_state;
};

/**
 * struct devfreq_governor - Devfreq policy governor
 * @node:               list node - contains registered devfreq governors
 * @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.
 * @event_handler:      Callback for devfreq core framework to notify events
 *                      to governors. Events include per device governor
 *                      init and exit, opp changes out of devfreq, suspend
 *                      and resume of per device devfreq during device idle.
 *
 * Note that the callbacks are called with devfreq->lock locked by devfreq.
 */
struct devfreq_governor {
        struct list_head node;

        const char name[DEVFREQ_NAME_LEN];
        int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
        int (*event_handler)(struct devfreq *devfreq,
                                unsigned int event, void *data);
};

/**
 * 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.
 * @governor_name:      devfreq governor name for use with this devfreq
 * @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.
 * @work:       delayed work for load monitoring.
 * @previous_freq:      previously configured frequency value.
 * @data:       Private data of the governor. The devfreq framework does not
 *              touch this.
 * @min_freq:   Limit minimum frequency requested by user (0: none)
 * @max_freq:   Limit maximum frequency requested by user (0: none)
 * @stop_polling:        devfreq polling status of a device.
 * @total_trans:        Number of devfreq transitions
 * @trans_table:        Statistics of devfreq transitions
 * @time_in_state:      Statistics of devfreq states
 * @last_stat_updated:  The last time stat updated
 *
 * 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;
        char governor_name[DEVFREQ_NAME_LEN];
        struct notifier_block nb;
        struct delayed_work work;

        unsigned long previous_freq;

        void *data; /* private data for governors */

        unsigned long min_freq;
        unsigned long max_freq;
        bool stop_polling;

        /* information for device frequency transition */
        unsigned int total_trans;
        unsigned int *trans_table;
        unsigned long *time_in_state;
        unsigned long last_stat_updated;
};

#if defined(CONFIG_PM_DEVFREQ)
extern struct devfreq *devfreq_add_device(struct device *dev,
                                  struct devfreq_dev_profile *profile,
                                  const char *governor_name,
                                  void *data);
extern int devfreq_remove_device(struct devfreq *devfreq);

/* Supposed to be called by PM_SLEEP/PM_RUNTIME callbacks */
extern int devfreq_suspend_device(struct devfreq *devfreq);
extern int devfreq_resume_device(struct devfreq *devfreq);

/* Helper functions for devfreq user device driver with OPP. */
extern struct dev_pm_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);

#if IS_ENABLED(CONFIG_DEVFREQ_GOV_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 inline struct devfreq *devfreq_add_device(struct device *dev,
                                          struct devfreq_dev_profile *profile,
                                          const char *governor_name,
                                          void *data)
{
        return NULL;
}

static inline int devfreq_remove_device(struct devfreq *devfreq)
{
        return 0;
}

static inline int devfreq_suspend_device(struct devfreq *devfreq)
{
        return 0;
}

static inline int devfreq_resume_device(struct devfreq *devfreq)
{
        return 0;
}

static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
                                           unsigned long *freq, u32 flags)
{
        return ERR_PTR(-EINVAL);
}

static inline int devfreq_register_opp_notifier(struct device *dev,
                                         struct devfreq *devfreq)
{
        return -EINVAL;
}

static inline int devfreq_unregister_opp_notifier(struct device *dev,
                                           struct devfreq *devfreq)
{
        return -EINVAL;
}

#endif /* CONFIG_PM_DEVFREQ */

#endif /* __LINUX_DEVFREQ_H__ */