/*
 *  linux/drivers/thermal/cpu_cooling.c
 *
 *  Copyright (C) 2012  Samsung Electronics Co., Ltd(http://www.samsung.com)
 *  Copyright (C) 2012  Amit Daniel <amit.kachhap@linaro.org>
 *
 *  Copyright (C) 2014  Viresh Kumar <viresh.kumar@linaro.org>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
#include <linux/module.h>
#include <linux/thermal.h>
#include <linux/cpufreq.h>
#include <linux/err.h>
#include <linux/pm_opp.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/cpu_cooling.h>

#include <trace/events/thermal.h>

/*
 * Cooling state <-> CPUFreq frequency
 *
 * Cooling states are translated to frequencies throughout this driver and this
 * is the relation between them.
 *
 * Highest cooling state corresponds to lowest possible frequency.
 *
 * i.e.
 *      level 0 --> 1st Max Freq
 *      level 1 --> 2nd Max Freq
 *      ...
 */

/**
 * struct power_table - frequency to power conversion
 * @frequency:  frequency in KHz
 * @power:      power in mW
 *
 * This structure is built when the cooling device registers and helps
 * in translating frequency to power and viceversa.
 */
struct power_table {
        u32 frequency;
        u32 power;
};

/**
 * struct cpufreq_cooling_device - data for cooling device with cpufreq
 * @id: unique integer value corresponding to each cpufreq_cooling_device
 *      registered.
 * @cool_dev: thermal_cooling_device pointer to keep track of the
 *      registered cooling device.
 * @cpufreq_state: integer value representing the current state of cpufreq
 *      cooling devices.
 * @clipped_freq: integer value representing the absolute value of the clipped
 *      frequency.
 * @max_level: maximum cooling level. One less than total number of valid
 *      cpufreq frequencies.
 * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
 * @node: list_head to link all cpufreq_cooling_device together.
 * @last_load: load measured by the latest call to cpufreq_get_actual_power()
 * @time_in_idle: previous reading of the absolute time that this cpu was idle
 * @time_in_idle_timestamp: wall time of the last invocation of
 *      get_cpu_idle_time_us()
 * @dyn_power_table: array of struct power_table for frequency to power
 *      conversion, sorted in ascending order.
 * @dyn_power_table_entries: number of entries in the @dyn_power_table array
 * @cpu_dev: the first cpu_device from @allowed_cpus that has OPPs registered
 * @plat_get_static_power: callback to calculate the static power
 *
 * This structure is required for keeping information of each registered
 * cpufreq_cooling_device.
 */
struct cpufreq_cooling_device {
        int id;
        struct thermal_cooling_device *cool_dev;
        unsigned int cpufreq_state;
        unsigned int clipped_freq;
        unsigned int max_level;
        unsigned int *freq_table;       /* In descending order */
        struct cpumask allowed_cpus;
        struct list_head node;
        u32 last_load;
        u64 *time_in_idle;
        u64 *time_in_idle_timestamp;
        struct power_table *dyn_power_table;
        int dyn_power_table_entries;
        struct device *cpu_dev;
        get_static_t plat_get_static_power;
};
static DEFINE_IDR(cpufreq_idr);
static DEFINE_MUTEX(cooling_cpufreq_lock);

static unsigned int cpufreq_dev_count;

static DEFINE_MUTEX(cooling_list_lock);
static LIST_HEAD(cpufreq_dev_list);

/**
 * get_idr - function to get a unique id.
 * @idr: struct idr * handle used to create a id.
 * @id: int * value generated by this function.
 *
 * This function will populate @id with an unique
 * id, using the idr API.
 *
 * Return: 0 on success, an error code on failure.
 */
static int get_idr(struct idr *idr, int *id)
{
        int ret;

        mutex_lock(&cooling_cpufreq_lock);
        ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
        mutex_unlock(&cooling_cpufreq_lock);
        if (unlikely(ret < 0))
                return ret;
        *id = ret;

        return 0;
}

/**
 * release_idr - function to free the unique id.
 * @idr: struct idr * handle used for creating the id.
 * @id: int value representing the unique id.
 */
static void release_idr(struct idr *idr, int id)
{
        mutex_lock(&cooling_cpufreq_lock);
        idr_remove(idr, id);
        mutex_unlock(&cooling_cpufreq_lock);
}

/* Below code defines functions to be used for cpufreq as cooling device */

/**
 * get_level: Find the level for a particular frequency
 * @cpufreq_dev: cpufreq_dev for which the property is required
 * @freq: Frequency
 *
 * Return: level on success, THERMAL_CSTATE_INVALID on error.
 */
static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_dev,
                               unsigned int freq)
{
        unsigned long level;

        for (level = 0; level <= cpufreq_dev->max_level; level++) {
                if (freq == cpufreq_dev->freq_table[level])
                        return level;

                if (freq > cpufreq_dev->freq_table[level])
                        break;
        }

        return THERMAL_CSTATE_INVALID;
}

/**
 * cpufreq_cooling_get_level - for a given cpu, return the cooling level.
 * @cpu: cpu for which the level is required
 * @freq: the frequency of interest
 *
 * This function will match the cooling level corresponding to the
 * requested @freq and return it.
 *
 * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
 * otherwise.
 */
unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
{
        struct cpufreq_cooling_device *cpufreq_dev;

        mutex_lock(&cooling_list_lock);
        list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
                if (cpumask_test_cpu(cpu, &cpufreq_dev->allowed_cpus)) {
                        mutex_unlock(&cooling_list_lock);
                        return get_level(cpufreq_dev, freq);
                }
        }
        mutex_unlock(&cooling_list_lock);

        pr_err("%s: cpu:%d not part of any cooling device\n", __func__, cpu);
        return THERMAL_CSTATE_INVALID;
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);

/**
 * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
 * @nb: struct notifier_block * with callback info.
 * @event: value showing cpufreq event for which this function invoked.
 * @data: callback-specific data
 *
 * Callback to hijack the notification on cpufreq policy transition.
 * Every time there is a change in policy, we will intercept and
 * update the cpufreq policy with thermal constraints.
 *
 * Return: 0 (success)
 */
static int cpufreq_thermal_notifier(struct notifier_block *nb,
                                    unsigned long event, void *data)
{
        struct cpufreq_policy *policy = data;
        unsigned long clipped_freq;
        struct cpufreq_cooling_device *cpufreq_dev;

        if (event != CPUFREQ_ADJUST)
                return NOTIFY_DONE;

        mutex_lock(&cooling_list_lock);
        list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
                if (!cpumask_test_cpu(policy->cpu, &cpufreq_dev->allowed_cpus))
                        continue;

                /*
                 * policy->max is the maximum allowed frequency defined by user
                 * and clipped_freq is the maximum that thermal constraints
                 * allow.
                 *
                 * If clipped_freq is lower than policy->max, then we need to
                 * readjust policy->max.
                 *
                 * But, if clipped_freq is greater than policy->max, we don't
                 * need to do anything.
                 */
                clipped_freq = cpufreq_dev->clipped_freq;

                if (policy->max > clipped_freq)
                        cpufreq_verify_within_limits(policy, 0, clipped_freq);
                break;
        }
        mutex_unlock(&cooling_list_lock);

        return NOTIFY_OK;
}

/**
 * build_dyn_power_table() - create a dynamic power to frequency table
 * @cpufreq_device:     the cpufreq cooling device in which to store the table
 * @capacitance: dynamic power coefficient for these cpus
 *
 * Build a dynamic power to frequency table for this cpu and store it
 * in @cpufreq_device.  This table will be used in cpu_power_to_freq() and
 * cpu_freq_to_power() to convert between power and frequency
 * efficiently.  Power is stored in mW, frequency in KHz.  The
 * resulting table is in ascending order.
 *
 * Return: 0 on success, -EINVAL if there are no OPPs for any CPUs,
 * -ENOMEM if we run out of memory or -EAGAIN if an OPP was
 * added/enabled while the function was executing.
 */
static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
                                 u32 capacitance)
{
        struct power_table *power_table;
        struct dev_pm_opp *opp;
        struct device *dev = NULL;
        int num_opps = 0, cpu, i, ret = 0;
        unsigned long freq;

        for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
                dev = get_cpu_device(cpu);
                if (!dev) {
                        dev_warn(&cpufreq_device->cool_dev->device,
                                 "No cpu device for cpu %d\n", cpu);
                        continue;
                }

                num_opps = dev_pm_opp_get_opp_count(dev);
                if (num_opps > 0)
                        break;
                else if (num_opps < 0)
                        return num_opps;
        }

        if (num_opps == 0)
                return -EINVAL;

        power_table = kcalloc(num_opps, sizeof(*power_table), GFP_KERNEL);
        if (!power_table)
                return -ENOMEM;

        rcu_read_lock();

        for (freq = 0, i = 0;
             opp = dev_pm_opp_find_freq_ceil(dev, &freq), !IS_ERR(opp);
             freq++, i++) {
                u32 freq_mhz, voltage_mv;
                u64 power;

                if (i >= num_opps) {
                        rcu_read_unlock();
                        ret = -EAGAIN;
                        goto free_power_table;
                }

                freq_mhz = freq / 1000000;
                voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;

                /*
                 * Do the multiplication with MHz and millivolt so as
                 * to not overflow.
                 */
                power = (u64)capacitance * freq_mhz * voltage_mv * voltage_mv;
                do_div(power, 1000000000);

                /* frequency is stored in power_table in KHz */
                power_table[i].frequency = freq / 1000;

                /* power is stored in mW */
                power_table[i].power = power;
        }

        rcu_read_unlock();

        if (i != num_opps) {
                ret = PTR_ERR(opp);
                goto free_power_table;
        }

        cpufreq_device->cpu_dev = dev;
        cpufreq_device->dyn_power_table = power_table;
        cpufreq_device->dyn_power_table_entries = i;

        return 0;

free_power_table:
        kfree(power_table);

        return ret;
}

static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_device,
                             u32 freq)
{
        int i;
        struct power_table *pt = cpufreq_device->dyn_power_table;

        for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
                if (freq < pt[i].frequency)
                        break;

        return pt[i - 1].power;
}

static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_device,
                             u32 power)
{
        int i;
        struct power_table *pt = cpufreq_device->dyn_power_table;

        for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
                if (power < pt[i].power)
                        break;

        return pt[i - 1].frequency;
}

/**
 * get_load() - get load for a cpu since last updated
 * @cpufreq_device:     &struct cpufreq_cooling_device for this cpu
 * @cpu:        cpu number
 * @cpu_idx:    index of the cpu in cpufreq_device->allowed_cpus
 *
 * Return: The average load of cpu @cpu in percentage since this
 * function was last called.
 */
static u32 get_load(struct cpufreq_cooling_device *cpufreq_device, int cpu,
                    int cpu_idx)
{
        u32 load;
        u64 now, now_idle, delta_time, delta_idle;

        now_idle = get_cpu_idle_time(cpu, &now, 0);
        delta_idle = now_idle - cpufreq_device->time_in_idle[cpu_idx];
        delta_time = now - cpufreq_device->time_in_idle_timestamp[cpu_idx];

        if (delta_time <= delta_idle)
                load = 0;
        else
                load = div64_u64(100 * (delta_time - delta_idle), delta_time);

        cpufreq_device->time_in_idle[cpu_idx] = now_idle;
        cpufreq_device->time_in_idle_timestamp[cpu_idx] = now;

        return load;
}

/**
 * get_static_power() - calculate the static power consumed by the cpus
 * @cpufreq_device:     struct &cpufreq_cooling_device for this cpu cdev
 * @tz:         thermal zone device in which we're operating
 * @freq:       frequency in KHz
 * @power:      pointer in which to store the calculated static power
 *
 * Calculate the static power consumed by the cpus described by
 * @cpu_actor running at frequency @freq.  This function relies on a
 * platform specific function that should have been provided when the
 * actor was registered.  If it wasn't, the static power is assumed to
 * be negligible.  The calculated static power is stored in @power.
 *
 * Return: 0 on success, -E* on failure.
 */
static int get_static_power(struct cpufreq_cooling_device *cpufreq_device,
                            struct thermal_zone_device *tz, unsigned long freq,
                            u32 *power)
{
        struct dev_pm_opp *opp;
        unsigned long voltage;
        struct cpumask *cpumask = &cpufreq_device->allowed_cpus;
        unsigned long freq_hz = freq * 1000;

        if (!cpufreq_device->plat_get_static_power ||
            !cpufreq_device->cpu_dev) {
                *power = 0;
                return 0;
        }

        rcu_read_lock();

        opp = dev_pm_opp_find_freq_exact(cpufreq_device->cpu_dev, freq_hz,
                                         true);
        voltage = dev_pm_opp_get_voltage(opp);

        rcu_read_unlock();

        if (voltage == 0) {
                dev_warn_ratelimited(cpufreq_device->cpu_dev,
                                     "Failed to get voltage for frequency %lu: %ld\n",
                                     freq_hz, IS_ERR(opp) ? PTR_ERR(opp) : 0);
                return -EINVAL;
        }

        return cpufreq_device->plat_get_static_power(cpumask, tz->passive_delay,
                                                     voltage, power);
}

/**
 * get_dynamic_power() - calculate the dynamic power
 * @cpufreq_device:     &cpufreq_cooling_device for this cdev
 * @freq:       current frequency
 *
 * Return: the dynamic power consumed by the cpus described by
 * @cpufreq_device.
 */
static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_device,
                             unsigned long freq)
{
        u32 raw_cpu_power;

        raw_cpu_power = cpu_freq_to_power(cpufreq_device, freq);
        return (raw_cpu_power * cpufreq_device->last_load) / 100;
}

/* cpufreq cooling device callback functions are defined below */

/**
 * cpufreq_get_max_state - callback function to get the max cooling state.
 * @cdev: thermal cooling device pointer.
 * @state: fill this variable with the max cooling state.
 *
 * Callback for the thermal cooling device to return the cpufreq
 * max cooling state.
 *
 * Return: 0 on success, an error code otherwise.
 */
static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
                                 unsigned long *state)
{
        struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;

        *state = cpufreq_device->max_level;
        return 0;
}

/**
 * cpufreq_get_cur_state - callback function to get the current cooling state.
 * @cdev: thermal cooling device pointer.
 * @state: fill this variable with the current cooling state.
 *
 * Callback for the thermal cooling device to return the cpufreq
 * current cooling state.
 *
 * Return: 0 on success, an error code otherwise.
 */
static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
                                 unsigned long *state)
{
        struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;

        *state = cpufreq_device->cpufreq_state;

        return 0;
}

/**
 * cpufreq_set_cur_state - callback function to set the current cooling state.
 * @cdev: thermal cooling device pointer.
 * @state: set this variable to the current cooling state.
 *
 * Callback for the thermal cooling device to change the cpufreq
 * current cooling state.
 *
 * Return: 0 on success, an error code otherwise.
 */
static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
                                 unsigned long state)
{
        struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
        unsigned int cpu = cpumask_any(&cpufreq_device->allowed_cpus);
        unsigned int clip_freq;

        /* Request state should be less than max_level */
        if (WARN_ON(state > cpufreq_device->max_level))
                return -EINVAL;

        /* Check if the old cooling action is same as new cooling action */
        if (cpufreq_device->cpufreq_state == state)
                return 0;

        clip_freq = cpufreq_device->freq_table[state];
        cpufreq_device->cpufreq_state = state;
        cpufreq_device->clipped_freq = clip_freq;

        cpufreq_update_policy(cpu);

        return 0;
}

/**
 * cpufreq_get_requested_power() - get the current power
 * @cdev:       &thermal_cooling_device pointer
 * @tz:         a valid thermal zone device pointer
 * @power:      pointer in which to store the resulting power
 *
 * Calculate the current power consumption of the cpus in milliwatts
 * and store it in @power.  This function should actually calculate
 * the requested power, but it's hard to get the frequency that
 * cpufreq would have assigned if there were no thermal limits.
 * Instead, we calculate the current power on the assumption that the
 * immediate future will look like the immediate past.
 *
 * We use the current frequency and the average load since this
 * function was last called.  In reality, there could have been
 * multiple opps since this function was last called and that affects
 * the load calculation.  While it's not perfectly accurate, this
 * simplification is good enough and works.  REVISIT this, as more
 * complex code may be needed if experiments show that it's not
 * accurate enough.
 *
 * Return: 0 on success, -E* if getting the static power failed.
 */
static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
                                       struct thermal_zone_device *tz,
                                       u32 *power)
{
        unsigned long freq;
        int i = 0, cpu, ret;
        u32 static_power, dynamic_power, total_load = 0;
        struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
        u32 *load_cpu = NULL;

        cpu = cpumask_any_and(&cpufreq_device->allowed_cpus, cpu_online_mask);

        /*
         * All the CPUs are offline, thus the requested power by
         * the cdev is 0
         */
        if (cpu >= nr_cpu_ids) {
                *power = 0;
                return 0;
        }

        freq = cpufreq_quick_get(cpu);

        if (trace_thermal_power_cpu_get_power_enabled()) {
                u32 ncpus = cpumask_weight(&cpufreq_device->allowed_cpus);

                load_cpu = kcalloc(ncpus, sizeof(*load_cpu), GFP_KERNEL);
        }

        for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
                u32 load;

                if (cpu_online(cpu))
                        load = get_load(cpufreq_device, cpu, i);
                else
                        load = 0;

                total_load += load;
                if (trace_thermal_power_cpu_limit_enabled() && load_cpu)
                        load_cpu[i] = load;

                i++;
        }

        cpufreq_device->last_load = total_load;

        dynamic_power = get_dynamic_power(cpufreq_device, freq);
        ret = get_static_power(cpufreq_device, tz, freq, &static_power);
        if (ret) {
                kfree(load_cpu);
                return ret;
        }

        if (load_cpu) {
                trace_thermal_power_cpu_get_power(
                        &cpufreq_device->allowed_cpus,
                        freq, load_cpu, i, dynamic_power, static_power);

                kfree(load_cpu);
        }

        *power = static_power + dynamic_power;
        return 0;
}

/**
 * cpufreq_state2power() - convert a cpu cdev state to power consumed
 * @cdev:       &thermal_cooling_device pointer
 * @tz:         a valid thermal zone device pointer
 * @state:      cooling device state to be converted
 * @power:      pointer in which to store the resulting power
 *
 * Convert cooling device state @state into power consumption in
 * milliwatts assuming 100% load.  Store the calculated power in
 * @power.
 *
 * Return: 0 on success, -EINVAL if the cooling device state could not
 * be converted into a frequency or other -E* if there was an error
 * when calculating the static power.
 */
static int cpufreq_state2power(struct thermal_cooling_device *cdev,
                               struct thermal_zone_device *tz,
                               unsigned long state, u32 *power)
{
        unsigned int freq, num_cpus;
        cpumask_t cpumask;
        u32 static_power, dynamic_power;
        int ret;
        struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;

        cpumask_and(&cpumask, &cpufreq_device->allowed_cpus, cpu_online_mask);
        num_cpus = cpumask_weight(&cpumask);

        /* None of our cpus are online, so no power */
        if (num_cpus == 0) {
                *power = 0;
                return 0;
        }

        freq = cpufreq_device->freq_table[state];
        if (!freq)
                return -EINVAL;

        dynamic_power = cpu_freq_to_power(cpufreq_device, freq) * num_cpus;
        ret = get_static_power(cpufreq_device, tz, freq, &static_power);
        if (ret)
                return ret;

        *power = static_power + dynamic_power;
        return 0;
}

/**
 * cpufreq_power2state() - convert power to a cooling device state
 * @cdev:       &thermal_cooling_device pointer
 * @tz:         a valid thermal zone device pointer
 * @power:      power in milliwatts to be converted
 * @state:      pointer in which to store the resulting state
 *
 * Calculate a cooling device state for the cpus described by @cdev
 * that would allow them to consume at most @power mW and store it in
 * @state.  Note that this calculation depends on external factors
 * such as the cpu load or the current static power.  Calling this
 * function with the same power as input can yield different cooling
 * device states depending on those external factors.
 *
 * Return: 0 on success, -ENODEV if no cpus are online or -EINVAL if
 * the calculated frequency could not be converted to a valid state.
 * The latter should not happen unless the frequencies available to
 * cpufreq have changed since the initialization of the cpu cooling
 * device.
 */
static int cpufreq_power2state(struct thermal_cooling_device *cdev,
                               struct thermal_zone_device *tz, u32 power,
                               unsigned long *state)
{
        unsigned int cpu, cur_freq, target_freq;
        int ret;
        s32 dyn_power;
        u32 last_load, normalised_power, static_power;
        struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;

        cpu = cpumask_any_and(&cpufreq_device->allowed_cpus, cpu_online_mask);

        /* None of our cpus are online */
        if (cpu >= nr_cpu_ids)
                return -ENODEV;

        cur_freq = cpufreq_quick_get(cpu);
        ret = get_static_power(cpufreq_device, tz, cur_freq, &static_power);
        if (ret)
                return ret;

        dyn_power = power - static_power;
        dyn_power = dyn_power > 0 ? dyn_power : 0;
        last_load = cpufreq_device->last_load ?: 1;
        normalised_power = (dyn_power * 100) / last_load;
        target_freq = cpu_power_to_freq(cpufreq_device, normalised_power);

        *state = cpufreq_cooling_get_level(cpu, target_freq);
        if (*state == THERMAL_CSTATE_INVALID) {
                dev_warn_ratelimited(&cdev->device,
                                     "Failed to convert %dKHz for cpu %d into a cdev state\n",
                                     target_freq, cpu);
                return -EINVAL;
        }

        trace_thermal_power_cpu_limit(&cpufreq_device->allowed_cpus,
                                      target_freq, *state, power);
        return 0;
}

/* Bind cpufreq callbacks to thermal cooling device ops */
static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
        .get_max_state = cpufreq_get_max_state,
        .get_cur_state = cpufreq_get_cur_state,
        .set_cur_state = cpufreq_set_cur_state,
};

/* Notifier for cpufreq policy change */
static struct notifier_block thermal_cpufreq_notifier_block = {
        .notifier_call = cpufreq_thermal_notifier,
};

static unsigned int find_next_max(struct cpufreq_frequency_table *table,
                                  unsigned int prev_max)
{
        struct cpufreq_frequency_table *pos;
        unsigned int max = 0;

        cpufreq_for_each_valid_entry(pos, table) {
                if (pos->frequency > max && pos->frequency < prev_max)
                        max = pos->frequency;
        }

        return max;
}

/**
 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 * @np: a valid struct device_node to the cooling device device tree node
 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 * Normally this should be same as cpufreq policy->related_cpus.
 * @capacitance: dynamic power coefficient for these cpus
 * @plat_static_func: function to calculate the static power consumed by these
 *                    cpus (optional)
 *
 * This interface function registers the cpufreq cooling device with the name
 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 * cooling devices. It also gives the opportunity to link the cooling device
 * with a device tree node, in order to bind it via the thermal DT code.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
static struct thermal_cooling_device *
__cpufreq_cooling_register(struct device_node *np,
                        const struct cpumask *clip_cpus, u32 capacitance,
                        get_static_t plat_static_func)
{
        struct thermal_cooling_device *cool_dev;
        struct cpufreq_cooling_device *cpufreq_dev;
        char dev_name[THERMAL_NAME_LENGTH];
        struct cpufreq_frequency_table *pos, *table;
        unsigned int freq, i, num_cpus;
        int ret;

        table = cpufreq_frequency_get_table(cpumask_first(clip_cpus));
        if (!table) {
                pr_debug("%s: CPUFreq table not found\n", __func__);
                return ERR_PTR(-EPROBE_DEFER);
        }

        cpufreq_dev = kzalloc(sizeof(*cpufreq_dev), GFP_KERNEL);
        if (!cpufreq_dev)
                return ERR_PTR(-ENOMEM);

        num_cpus = cpumask_weight(clip_cpus);
        cpufreq_dev->time_in_idle = kcalloc(num_cpus,
                                            sizeof(*cpufreq_dev->time_in_idle),
                                            GFP_KERNEL);
        if (!cpufreq_dev->time_in_idle) {
                cool_dev = ERR_PTR(-ENOMEM);
                goto free_cdev;
        }

        cpufreq_dev->time_in_idle_timestamp =
                kcalloc(num_cpus, sizeof(*cpufreq_dev->time_in_idle_timestamp),
                        GFP_KERNEL);
        if (!cpufreq_dev->time_in_idle_timestamp) {
                cool_dev = ERR_PTR(-ENOMEM);
                goto free_time_in_idle;
        }

        /* Find max levels */
        cpufreq_for_each_valid_entry(pos, table)
                cpufreq_dev->max_level++;

        cpufreq_dev->freq_table = kmalloc(sizeof(*cpufreq_dev->freq_table) *
                                          cpufreq_dev->max_level, GFP_KERNEL);
        if (!cpufreq_dev->freq_table) {
                cool_dev = ERR_PTR(-ENOMEM);
                goto free_time_in_idle_timestamp;
        }

        /* max_level is an index, not a counter */
        cpufreq_dev->max_level--;

        cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);

        if (capacitance) {
                cpufreq_cooling_ops.get_requested_power =
                        cpufreq_get_requested_power;
                cpufreq_cooling_ops.state2power = cpufreq_state2power;
                cpufreq_cooling_ops.power2state = cpufreq_power2state;
                cpufreq_dev->plat_get_static_power = plat_static_func;

                ret = build_dyn_power_table(cpufreq_dev, capacitance);
                if (ret) {
                        cool_dev = ERR_PTR(ret);
                        goto free_table;
                }
        }

        ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
        if (ret) {
                cool_dev = ERR_PTR(ret);
                goto free_power_table;
        }

        snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
                 cpufreq_dev->id);

        cool_dev = thermal_of_cooling_device_register(np, dev_name, cpufreq_dev,
                                                      &cpufreq_cooling_ops);
        if (IS_ERR(cool_dev))
                goto remove_idr;

        /* Fill freq-table in descending order of frequencies */
        for (i = 0, freq = -1; i <= cpufreq_dev->max_level; i++) {
                freq = find_next_max(table, freq);
                cpufreq_dev->freq_table[i] = freq;

                /* Warn for duplicate entries */
                if (!freq)
                        pr_warn("%s: table has duplicate entries\n", __func__);
                else
                        pr_debug("%s: freq:%u KHz\n", __func__, freq);
        }

        cpufreq_dev->clipped_freq = cpufreq_dev->freq_table[0];
        cpufreq_dev->cool_dev = cool_dev;

        mutex_lock(&cooling_cpufreq_lock);

        mutex_lock(&cooling_list_lock);
        list_add(&cpufreq_dev->node, &cpufreq_dev_list);
        mutex_unlock(&cooling_list_lock);

        /* Register the notifier for first cpufreq cooling device */
        if (!cpufreq_dev_count++)
                cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
                                          CPUFREQ_POLICY_NOTIFIER);
        mutex_unlock(&cooling_cpufreq_lock);

        return cool_dev;

remove_idr:
        release_idr(&cpufreq_idr, cpufreq_dev->id);
free_power_table:
        kfree(cpufreq_dev->dyn_power_table);
free_table:
        kfree(cpufreq_dev->freq_table);
free_time_in_idle_timestamp:
        kfree(cpufreq_dev->time_in_idle_timestamp);
free_time_in_idle:
        kfree(cpufreq_dev->time_in_idle);
free_cdev:
        kfree(cpufreq_dev);

        return cool_dev;
}

/**
 * cpufreq_cooling_register - function to create cpufreq cooling device.
 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 *
 * This interface function registers the cpufreq cooling device with the name
 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 * cooling devices.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
struct thermal_cooling_device *
cpufreq_cooling_register(const struct cpumask *clip_cpus)
{
        return __cpufreq_cooling_register(NULL, clip_cpus, 0, NULL);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_register);

/**
 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 * @np: a valid struct device_node to the cooling device device tree node
 * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
 *
 * This interface function registers the cpufreq cooling device with the name
 * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
 * cooling devices. Using this API, the cpufreq cooling device will be
 * linked to the device tree node provided.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
struct thermal_cooling_device *
of_cpufreq_cooling_register(struct device_node *np,
                            const struct cpumask *clip_cpus)
{
        if (!np)
                return ERR_PTR(-EINVAL);

        return __cpufreq_cooling_register(np, clip_cpus, 0, NULL);
}
EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);

/**
 * cpufreq_power_cooling_register() - create cpufreq cooling device with power extensions
 * @clip_cpus:  cpumask of cpus where the frequency constraints will happen
 * @capacitance:        dynamic power coefficient for these cpus
 * @plat_static_func:   function to calculate the static power consumed by these
 *                      cpus (optional)
 *
 * This interface function registers the cpufreq cooling device with
 * the name "thermal-cpufreq-%x".  This api can support multiple
 * instances of cpufreq cooling devices.  Using this function, the
 * cooling device will implement the power extensions by using a
 * simple cpu power model.  The cpus must have registered their OPPs
 * using the OPP library.
 *
 * An optional @plat_static_func may be provided to calculate the
 * static power consumed by these cpus.  If the platform's static
 * power consumption is unknown or negligible, make it NULL.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
struct thermal_cooling_device *
cpufreq_power_cooling_register(const struct cpumask *clip_cpus, u32 capacitance,
                               get_static_t plat_static_func)
{
        return __cpufreq_cooling_register(NULL, clip_cpus, capacitance,
                                plat_static_func);
}
EXPORT_SYMBOL(cpufreq_power_cooling_register);

/**
 * of_cpufreq_power_cooling_register() - create cpufreq cooling device with power extensions
 * @np: a valid struct device_node to the cooling device device tree node
 * @clip_cpus:  cpumask of cpus where the frequency constraints will happen
 * @capacitance:        dynamic power coefficient for these cpus
 * @plat_static_func:   function to calculate the static power consumed by these
 *                      cpus (optional)
 *
 * This interface function registers the cpufreq cooling device with
 * the name "thermal-cpufreq-%x".  This api can support multiple
 * instances of cpufreq cooling devices.  Using this API, the cpufreq
 * cooling device will be linked to the device tree node provided.
 * Using this function, the cooling device will implement the power
 * extensions by using a simple cpu power model.  The cpus must have
 * registered their OPPs using the OPP library.
 *

 * An optional @plat_static_func may be provided to calculate the
 * static power consumed by these cpus.  If the platform's static
 * power consumption is unknown or negligible, make it NULL.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * on failure, it returns a corresponding ERR_PTR().
 */
struct thermal_cooling_device *
of_cpufreq_power_cooling_register(struct device_node *np,
                                  const struct cpumask *clip_cpus,
                                  u32 capacitance,
                                  get_static_t plat_static_func)
{
        if (!np)
                return ERR_PTR(-EINVAL);

        return __cpufreq_cooling_register(np, clip_cpus, capacitance,
                                plat_static_func);
}
EXPORT_SYMBOL(of_cpufreq_power_cooling_register);

/**
 * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
 * @cdev: thermal cooling device pointer.
 *
 * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
 */
void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
{
        struct cpufreq_cooling_device *cpufreq_dev;

        if (!cdev)
                return;

        cpufreq_dev = cdev->devdata;

        /* Unregister the notifier for the last cpufreq cooling device */
        mutex_lock(&cooling_cpufreq_lock);
        if (!--cpufreq_dev_count)
                cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
                                            CPUFREQ_POLICY_NOTIFIER);

        mutex_lock(&cooling_list_lock);
        list_del(&cpufreq_dev->node);
        mutex_unlock(&cooling_list_lock);

        mutex_unlock(&cooling_cpufreq_lock);

        thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
        release_idr(&cpufreq_idr, cpufreq_dev->id);
        kfree(cpufreq_dev->dyn_power_table);
        kfree(cpufreq_dev->time_in_idle_timestamp);
        kfree(cpufreq_dev->time_in_idle);
        kfree(cpufreq_dev->freq_table);
        kfree(cpufreq_dev);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);