/*
 * devfreq_cooling: Thermal cooling device implementation for devices using
 *                  devfreq
 *
 * Copyright (C) 2014-2015 ARM Limited
 *
 * 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 program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * TODO:
 *    - If OPPs are added or removed after devfreq cooling has
 *      registered, the devfreq cooling won't react to it.
 */

#include <linux/devfreq.h>
#include <linux/devfreq_cooling.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/pm_opp.h>
#include <linux/thermal.h>

#include <trace/events/thermal.h>

static DEFINE_MUTEX(devfreq_lock);
static DEFINE_IDR(devfreq_idr);

/**
 * struct devfreq_cooling_device - Devfreq cooling device
 * @id:         unique integer value corresponding to each
 *              devfreq_cooling_device registered.
 * @cdev:       Pointer to associated thermal cooling device.
 * @devfreq:    Pointer to associated devfreq device.
 * @cooling_state:      Current cooling state.
 * @power_table:        Pointer to table with maximum power draw for each
 *                      cooling state. State is the index into the table, and
 *                      the power is in mW.
 * @freq_table: Pointer to a table with the frequencies sorted in descending
 *              order.  You can index the table by cooling device state
 * @freq_table_size:    Size of the @freq_table and @power_table
 * @power_ops:  Pointer to devfreq_cooling_power, used to generate the
 *              @power_table.
 */
struct devfreq_cooling_device {
        int id;
        struct thermal_cooling_device *cdev;
        struct devfreq *devfreq;
        unsigned long cooling_state;
        u32 *power_table;
        u32 *freq_table;
        size_t freq_table_size;
        struct devfreq_cooling_power *power_ops;
};

/**
 * 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(&devfreq_lock);
        ret = idr_alloc(idr, NULL, 0, 0, GFP_KERNEL);
        mutex_unlock(&devfreq_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(&devfreq_lock);
        idr_remove(idr, id);
        mutex_unlock(&devfreq_lock);
}

/**
 * partition_enable_opps() - disable all opps above a given state
 * @dfc:        Pointer to devfreq we are operating on
 * @cdev_state: cooling device state we're setting
 *
 * Go through the OPPs of the device, enabling all OPPs until
 * @cdev_state and disabling those frequencies above it.
 */
static int partition_enable_opps(struct devfreq_cooling_device *dfc,
                                 unsigned long cdev_state)
{
        int i;
        struct device *dev = dfc->devfreq->dev.parent;

        for (i = 0; i < dfc->freq_table_size; i++) {
                struct dev_pm_opp *opp;
                int ret = 0;
                unsigned int freq = dfc->freq_table[i];
                bool want_enable = i >= cdev_state ? true : false;

                rcu_read_lock();
                opp = dev_pm_opp_find_freq_exact(dev, freq, !want_enable);
                rcu_read_unlock();

                if (PTR_ERR(opp) == -ERANGE)
                        continue;
                else if (IS_ERR(opp))
                        return PTR_ERR(opp);

                if (want_enable)
                        ret = dev_pm_opp_enable(dev, freq);
                else
                        ret = dev_pm_opp_disable(dev, freq);

                if (ret)
                        return ret;
        }

        return 0;
}

static int devfreq_cooling_get_max_state(struct thermal_cooling_device *cdev,
                                         unsigned long *state)
{
        struct devfreq_cooling_device *dfc = cdev->devdata;

        *state = dfc->freq_table_size - 1;

        return 0;
}

static int devfreq_cooling_get_cur_state(struct thermal_cooling_device *cdev,
                                         unsigned long *state)
{
        struct devfreq_cooling_device *dfc = cdev->devdata;

        *state = dfc->cooling_state;

        return 0;
}

static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
                                         unsigned long state)
{
        struct devfreq_cooling_device *dfc = cdev->devdata;
        struct devfreq *df = dfc->devfreq;
        struct device *dev = df->dev.parent;
        int ret;

        if (state == dfc->cooling_state)
                return 0;

        dev_dbg(dev, "Setting cooling state %lu\n", state);

        if (state >= dfc->freq_table_size)
                return -EINVAL;

        ret = partition_enable_opps(dfc, state);
        if (ret)
                return ret;

        dfc->cooling_state = state;

        return 0;
}

/**
 * freq_get_state() - get the cooling state corresponding to a frequency
 * @dfc:        Pointer to devfreq cooling device
 * @freq:       frequency in Hz
 *
 * Return: the cooling state associated with the @freq, or
 * THERMAL_CSTATE_INVALID if it wasn't found.
 */
static unsigned long
freq_get_state(struct devfreq_cooling_device *dfc, unsigned long freq)
{
        int i;

        for (i = 0; i < dfc->freq_table_size; i++) {
                if (dfc->freq_table[i] == freq)
                        return i;
        }

        return THERMAL_CSTATE_INVALID;
}

/**
 * get_static_power() - calculate the static power
 * @dfc:        Pointer to devfreq cooling device
 * @freq:       Frequency in Hz
 *
 * Calculate the static power in milliwatts using the supplied
 * get_static_power().  The current voltage is calculated using the
 * OPP library.  If no get_static_power() was supplied, assume the
 * static power is negligible.
 */
static unsigned long
get_static_power(struct devfreq_cooling_device *dfc, unsigned long freq)
{
        struct devfreq *df = dfc->devfreq;
        struct device *dev = df->dev.parent;
        unsigned long voltage;
        struct dev_pm_opp *opp;

        if (!dfc->power_ops->get_static_power)
                return 0;

        rcu_read_lock();

        opp = dev_pm_opp_find_freq_exact(dev, freq, true);
        if (IS_ERR(opp) && (PTR_ERR(opp) == -ERANGE))
                opp = dev_pm_opp_find_freq_exact(dev, freq, false);

        voltage = dev_pm_opp_get_voltage(opp) / 1000; /* mV */

        rcu_read_unlock();

        if (voltage == 0) {
                dev_warn_ratelimited(dev,
                                     "Failed to get voltage for frequency %lu: %ld\n",
                                     freq, IS_ERR(opp) ? PTR_ERR(opp) : 0);
                return 0;
        }

        return dfc->power_ops->get_static_power(voltage);
}

/**
 * get_dynamic_power - calculate the dynamic power
 * @dfc:        Pointer to devfreq cooling device
 * @freq:       Frequency in Hz
 * @voltage:    Voltage in millivolts
 *
 * Calculate the dynamic power in milliwatts consumed by the device at
 * frequency @freq and voltage @voltage.  If the get_dynamic_power()
 * was supplied as part of the devfreq_cooling_power struct, then that
 * function is used.  Otherwise, a simple power model (Pdyn = Coeff *
 * Voltage^2 * Frequency) is used.
 */
static unsigned long
get_dynamic_power(struct devfreq_cooling_device *dfc, unsigned long freq,
                  unsigned long voltage)
{
        u64 power;
        u32 freq_mhz;
        struct devfreq_cooling_power *dfc_power = dfc->power_ops;

        if (dfc_power->get_dynamic_power)
                return dfc_power->get_dynamic_power(freq, voltage);

        freq_mhz = freq / 1000000;
        power = (u64)dfc_power->dyn_power_coeff * freq_mhz * voltage * voltage;
        do_div(power, 1000000000);

        return power;
}

static int devfreq_cooling_get_requested_power(struct thermal_cooling_device *cdev,
                                               struct thermal_zone_device *tz,
                                               u32 *power)
{
        struct devfreq_cooling_device *dfc = cdev->devdata;
        struct devfreq *df = dfc->devfreq;
        struct devfreq_dev_status *status = &df->last_status;
        unsigned long state;
        unsigned long freq = status->current_frequency;
        u32 dyn_power, static_power;

        /* Get dynamic power for state */
        state = freq_get_state(dfc, freq);
        if (state == THERMAL_CSTATE_INVALID)
                return -EAGAIN;

        dyn_power = dfc->power_table[state];

        /* Scale dynamic power for utilization */
        dyn_power = (dyn_power * status->busy_time) / status->total_time;

        /* Get static power */
        static_power = get_static_power(dfc, freq);

        trace_thermal_power_devfreq_get_power(cdev, status, freq, dyn_power,
                                              static_power);

        *power = dyn_power + static_power;

        return 0;
}

static int devfreq_cooling_state2power(struct thermal_cooling_device *cdev,
                                       struct thermal_zone_device *tz,
                                       unsigned long state,
                                       u32 *power)
{
        struct devfreq_cooling_device *dfc = cdev->devdata;
        unsigned long freq;
        u32 static_power;

        if (state >= dfc->freq_table_size)
                return -EINVAL;

        freq = dfc->freq_table[state];
        static_power = get_static_power(dfc, freq);

        *power = dfc->power_table[state] + static_power;
        return 0;
}

static int devfreq_cooling_power2state(struct thermal_cooling_device *cdev,
                                       struct thermal_zone_device *tz,
                                       u32 power, unsigned long *state)
{
        struct devfreq_cooling_device *dfc = cdev->devdata;
        struct devfreq *df = dfc->devfreq;
        struct devfreq_dev_status *status = &df->last_status;
        unsigned long freq = status->current_frequency;
        unsigned long busy_time;
        s32 dyn_power;
        u32 static_power;
        int i;

        static_power = get_static_power(dfc, freq);

        dyn_power = power - static_power;
        dyn_power = dyn_power > 0 ? dyn_power : 0;

        /* Scale dynamic power for utilization */
        busy_time = status->busy_time ?: 1;
        dyn_power = (dyn_power * status->total_time) / busy_time;

        /*
         * Find the first cooling state that is within the power
         * budget for dynamic power.
         */
        for (i = 0; i < dfc->freq_table_size - 1; i++)
                if (dyn_power >= dfc->power_table[i])
                        break;

        *state = i;
        trace_thermal_power_devfreq_limit(cdev, freq, *state, power);
        return 0;
}

static struct thermal_cooling_device_ops devfreq_cooling_ops = {
        .get_max_state = devfreq_cooling_get_max_state,
        .get_cur_state = devfreq_cooling_get_cur_state,
        .set_cur_state = devfreq_cooling_set_cur_state,
};

/**
 * devfreq_cooling_gen_tables() - Generate power and freq tables.
 * @dfc: Pointer to devfreq cooling device.
 *
 * Generate power and frequency tables: the power table hold the
 * device's maximum power usage at each cooling state (OPP).  The
 * static and dynamic power using the appropriate voltage and
 * frequency for the state, is acquired from the struct
 * devfreq_cooling_power, and summed to make the maximum power draw.
 *
 * The frequency table holds the frequencies in descending order.
 * That way its indexed by cooling device state.
 *
 * The tables are malloced, and pointers put in dfc.  They must be
 * freed when unregistering the devfreq cooling device.
 *
 * Return: 0 on success, negative error code on failure.
 */
static int devfreq_cooling_gen_tables(struct devfreq_cooling_device *dfc)
{
        struct devfreq *df = dfc->devfreq;
        struct device *dev = df->dev.parent;
        int ret, num_opps;
        unsigned long freq;
        u32 *power_table = NULL;
        u32 *freq_table;
        int i;

        num_opps = dev_pm_opp_get_opp_count(dev);

        if (dfc->power_ops) {
                power_table = kcalloc(num_opps, sizeof(*power_table),
                                      GFP_KERNEL);
                if (!power_table)
                        return -ENOMEM;
        }

        freq_table = kcalloc(num_opps, sizeof(*freq_table),
                             GFP_KERNEL);
        if (!freq_table) {
                ret = -ENOMEM;
                goto free_power_table;
        }

        for (i = 0, freq = ULONG_MAX; i < num_opps; i++, freq--) {
                unsigned long power_dyn, voltage;
                struct dev_pm_opp *opp;

                rcu_read_lock();

                opp = dev_pm_opp_find_freq_floor(dev, &freq);
                if (IS_ERR(opp)) {
                        rcu_read_unlock();
                        ret = PTR_ERR(opp);
                        goto free_tables;
                }

                voltage = dev_pm_opp_get_voltage(opp) / 1000; /* mV */

                rcu_read_unlock();

                if (dfc->power_ops) {
                        power_dyn = get_dynamic_power(dfc, freq, voltage);

                        dev_dbg(dev, "Dynamic power table: %lu MHz @ %lu mV: %lu = %lu mW\n",
                                freq / 1000000, voltage, power_dyn, power_dyn);

                        power_table[i] = power_dyn;
                }

                freq_table[i] = freq;
        }

        if (dfc->power_ops)
                dfc->power_table = power_table;

        dfc->freq_table = freq_table;
        dfc->freq_table_size = num_opps;

        return 0;

free_tables:
        kfree(freq_table);
free_power_table:
        kfree(power_table);

        return ret;
}

/**
 * of_devfreq_cooling_register_power() - Register devfreq cooling device,
 *                                      with OF and power information.
 * @np: Pointer to OF device_node.
 * @df: Pointer to devfreq device.
 * @dfc_power:  Pointer to devfreq_cooling_power.
 *
 * Register a devfreq cooling device.  The available OPPs must be
 * registered on the device.
 *
 * If @dfc_power is provided, the cooling device is registered with the
 * power extensions.  For the power extensions to work correctly,
 * devfreq should use the simple_ondemand governor, other governors
 * are not currently supported.
 */
struct thermal_cooling_device *
of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
                                  struct devfreq_cooling_power *dfc_power)
{
        struct thermal_cooling_device *cdev;
        struct devfreq_cooling_device *dfc;
        char dev_name[THERMAL_NAME_LENGTH];
        int err;

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

        dfc->devfreq = df;

        if (dfc_power) {
                dfc->power_ops = dfc_power;

                devfreq_cooling_ops.get_requested_power =
                        devfreq_cooling_get_requested_power;
                devfreq_cooling_ops.state2power = devfreq_cooling_state2power;
                devfreq_cooling_ops.power2state = devfreq_cooling_power2state;
        }

        err = devfreq_cooling_gen_tables(dfc);
        if (err)
                goto free_dfc;

        err = get_idr(&devfreq_idr, &dfc->id);
        if (err)
                goto free_tables;

        snprintf(dev_name, sizeof(dev_name), "thermal-devfreq-%d", dfc->id);

        cdev = thermal_of_cooling_device_register(np, dev_name, dfc,
                                                  &devfreq_cooling_ops);
        if (IS_ERR(cdev)) {
                err = PTR_ERR(cdev);
                dev_err(df->dev.parent,
                        "Failed to register devfreq cooling device (%d)\n",
                        err);
                goto release_idr;
        }

        dfc->cdev = cdev;

        return cdev;

release_idr:
        release_idr(&devfreq_idr, dfc->id);
free_tables:
        kfree(dfc->power_table);
        kfree(dfc->freq_table);
free_dfc:
        kfree(dfc);

        return ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(of_devfreq_cooling_register_power);

/**
 * of_devfreq_cooling_register() - Register devfreq cooling device,
 *                                with OF information.
 * @np: Pointer to OF device_node.
 * @df: Pointer to devfreq device.
 */
struct thermal_cooling_device *
of_devfreq_cooling_register(struct device_node *np, struct devfreq *df)
{
        return of_devfreq_cooling_register_power(np, df, NULL);
}
EXPORT_SYMBOL_GPL(of_devfreq_cooling_register);

/**
 * devfreq_cooling_register() - Register devfreq cooling device.
 * @df: Pointer to devfreq device.
 */
struct thermal_cooling_device *devfreq_cooling_register(struct devfreq *df)
{
        return of_devfreq_cooling_register(NULL, df);
}
EXPORT_SYMBOL_GPL(devfreq_cooling_register);

/**
 * devfreq_cooling_unregister() - Unregister devfreq cooling device.
 * @dfc: Pointer to devfreq cooling device to unregister.
 */
void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
{
        struct devfreq_cooling_device *dfc;

        if (!cdev)
                return;

        dfc = cdev->devdata;

        thermal_cooling_device_unregister(dfc->cdev);
        release_idr(&devfreq_idr, dfc->id);
        kfree(dfc->power_table);
        kfree(dfc->freq_table);

        kfree(dfc);
}
EXPORT_SYMBOL_GPL(devfreq_cooling_unregister);