// SPDX-License-Identifier: GPL-2.0
/*
 * Energy Model of devices
 *
 * Copyright (c) 2018-2021, Arm ltd.
 * Written by: Quentin Perret, Arm ltd.
 * Improvements provided by: Lukasz Luba, Arm ltd.
 */

#define pr_fmt(fmt) "energy_model: " fmt

#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/cpumask.h>
#include <linux/debugfs.h>
#include <linux/energy_model.h>
#include <linux/sched/topology.h>
#include <linux/slab.h>

#include "em_netlink.h"

/*
 * Mutex serializing the registrations of performance domains and letting
 * callbacks defined by drivers sleep.
 */
static DEFINE_MUTEX(em_pd_mutex);

/*
 * Manage performance domains with IDs. One can iterate the performance domains
 * through the list and pick one with their associated ID. The mutex serializes
 * the list access. When holding em_pd_list_mutex, em_pd_mutex should not be
 * taken to avoid potential deadlock.
 */
static DEFINE_IDA(em_pd_ida);
static LIST_HEAD(em_pd_list);
static DEFINE_MUTEX(em_pd_list_mutex);

static void em_cpufreq_update_efficiencies(struct device *dev,
                                           struct em_perf_state *table);
static void em_check_capacity_update(void);
static void em_update_workfn(struct work_struct *work);
static DECLARE_DELAYED_WORK(em_update_work, em_update_workfn);

static bool _is_cpu_device(struct device *dev)
{
        return (dev->bus == &cpu_subsys);
}

#ifdef CONFIG_DEBUG_FS
static struct dentry *rootdir;

struct em_dbg_info {
        struct em_perf_domain *pd;
        int ps_id;
};

#define DEFINE_EM_DBG_SHOW(name, fname)                                 \
static int em_debug_##fname##_show(struct seq_file *s, void *unused)    \
{                                                                       \
        struct em_dbg_info *em_dbg = s->private;                        \
        struct em_perf_state *table;                                    \
        unsigned long val;                                              \
                                                                        \
        rcu_read_lock();                                                \
        table = em_perf_state_from_pd(em_dbg->pd);                      \
        val = table[em_dbg->ps_id].name;                                \
        rcu_read_unlock();                                              \
                                                                        \
        seq_printf(s, "%lu\n", val);                                    \
        return 0;                                                       \
}                                                                       \
DEFINE_SHOW_ATTRIBUTE(em_debug_##fname)

DEFINE_EM_DBG_SHOW(frequency, frequency);
DEFINE_EM_DBG_SHOW(power, power);
DEFINE_EM_DBG_SHOW(cost, cost);
DEFINE_EM_DBG_SHOW(performance, performance);
DEFINE_EM_DBG_SHOW(flags, inefficiency);

static void em_debug_create_ps(struct em_perf_domain *em_pd,
                               struct em_dbg_info *em_dbg, int i,
                               struct dentry *pd)
{
        struct em_perf_state *table;
        unsigned long freq;
        struct dentry *d;
        char name[24];

        em_dbg[i].pd = em_pd;
        em_dbg[i].ps_id = i;

        rcu_read_lock();
        table = em_perf_state_from_pd(em_pd);
        freq = table[i].frequency;
        rcu_read_unlock();

        snprintf(name, sizeof(name), "ps:%lu", freq);

        /* Create per-ps directory */
        d = debugfs_create_dir(name, pd);
        debugfs_create_file("frequency", 0444, d, &em_dbg[i],
                            &em_debug_frequency_fops);
        debugfs_create_file("power", 0444, d, &em_dbg[i],
                            &em_debug_power_fops);
        debugfs_create_file("cost", 0444, d, &em_dbg[i],
                            &em_debug_cost_fops);
        debugfs_create_file("performance", 0444, d, &em_dbg[i],
                            &em_debug_performance_fops);
        debugfs_create_file("inefficient", 0444, d, &em_dbg[i],
                            &em_debug_inefficiency_fops);
}

static int em_debug_cpus_show(struct seq_file *s, void *unused)
{
        seq_printf(s, "%*pbl\n", cpumask_pr_args(to_cpumask(s->private)));

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(em_debug_cpus);

static int em_debug_flags_show(struct seq_file *s, void *unused)
{
        struct em_perf_domain *pd = s->private;

        seq_printf(s, "%#lx\n", pd->flags);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(em_debug_flags);

static int em_debug_id_show(struct seq_file *s, void *unused)
{
        struct em_perf_domain *pd = s->private;

        seq_printf(s, "%d\n", pd->id);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(em_debug_id);

static void em_debug_create_pd(struct device *dev)
{
        struct em_dbg_info *em_dbg;
        struct dentry *d;
        int i;

        /* Create the directory of the performance domain */
        d = debugfs_create_dir(dev_name(dev), rootdir);

        if (_is_cpu_device(dev))
                debugfs_create_file("cpus", 0444, d, dev->em_pd->cpus,
                                    &em_debug_cpus_fops);

        debugfs_create_file("flags", 0444, d, dev->em_pd,
                            &em_debug_flags_fops);

        debugfs_create_file("id", 0444, d, dev->em_pd, &em_debug_id_fops);

        em_dbg = devm_kcalloc(dev, dev->em_pd->nr_perf_states,
                              sizeof(*em_dbg), GFP_KERNEL);
        if (!em_dbg)
                return;

        /* Create a sub-directory for each performance state */
        for (i = 0; i < dev->em_pd->nr_perf_states; i++)
                em_debug_create_ps(dev->em_pd, em_dbg, i, d);

}

static void em_debug_remove_pd(struct device *dev)
{
        debugfs_lookup_and_remove(dev_name(dev), rootdir);
}

static int __init em_debug_init(void)
{
        /* Create /sys/kernel/debug/energy_model directory */
        rootdir = debugfs_create_dir("energy_model", NULL);

        return 0;
}
fs_initcall(em_debug_init);
#else /* CONFIG_DEBUG_FS */
static void em_debug_create_pd(struct device *dev) {}
static void em_debug_remove_pd(struct device *dev) {}
#endif

static void em_release_table_kref(struct kref *kref)
{
        /* It was the last owner of this table so we can free */
        kfree_rcu(container_of(kref, struct em_perf_table, kref), rcu);
}

/**
 * em_table_free() - Handles safe free of the EM table when needed
 * @table : EM table which is going to be freed
 *
 * No return values.
 */
void em_table_free(struct em_perf_table *table)
{
        kref_put(&table->kref, em_release_table_kref);
}

/**
 * em_table_alloc() - Allocate a new EM table
 * @pd          : EM performance domain for which this must be done
 *
 * Allocate a new EM table and initialize its kref to indicate that it
 * has a user.
 * Returns allocated table or NULL.
 */
struct em_perf_table *em_table_alloc(struct em_perf_domain *pd)
{
        struct em_perf_table *table;
        int table_size;

        table_size = sizeof(struct em_perf_state) * pd->nr_perf_states;

        table = kzalloc(sizeof(*table) + table_size, GFP_KERNEL);
        if (!table)
                return NULL;

        kref_init(&table->kref);

        return table;
}

static void em_init_performance(struct device *dev, struct em_perf_domain *pd,
                                struct em_perf_state *table, int nr_states)
{
        u64 fmax, max_cap;
        int i, cpu;

        /* This is needed only for CPUs and EAS skip other devices */
        if (!_is_cpu_device(dev))
                return;

        cpu = cpumask_first(em_span_cpus(pd));

        /*
         * Calculate the performance value for each frequency with
         * linear relationship. The final CPU capacity might not be ready at
         * boot time, but the EM will be updated a bit later with correct one.
         */
        fmax = (u64) table[nr_states - 1].frequency;
        max_cap = (u64) arch_scale_cpu_capacity(cpu);
        for (i = 0; i < nr_states; i++)
                table[i].performance = div64_u64(max_cap * table[i].frequency,
                                                 fmax);
}

static int em_compute_costs(struct device *dev, struct em_perf_state *table,
                            const struct em_data_callback *cb, int nr_states,
                            unsigned long flags)
{
        unsigned long prev_cost = ULONG_MAX;
        int i, ret;

        /* This is needed only for CPUs and EAS skip other devices */
        if (!_is_cpu_device(dev))
                return 0;

        /* Compute the cost of each performance state. */
        for (i = nr_states - 1; i >= 0; i--) {
                unsigned long power_res, cost;

                if ((flags & EM_PERF_DOMAIN_ARTIFICIAL) && cb->get_cost) {
                        ret = cb->get_cost(dev, table[i].frequency, &cost);
                        if (ret || !cost || cost > EM_MAX_POWER) {
                                dev_err(dev, "EM: invalid cost %lu %d\n",
                                        cost, ret);
                                return -EINVAL;
                        }
                } else {
                        /* increase resolution of 'cost' precision */
                        power_res = table[i].power * 10;
                        cost = power_res / table[i].performance;
                }

                table[i].cost = cost;

                if (table[i].cost >= prev_cost) {
                        table[i].flags = EM_PERF_STATE_INEFFICIENT;
                        dev_dbg(dev, "EM: OPP:%lu is inefficient\n",
                                table[i].frequency);
                } else {
                        prev_cost = table[i].cost;
                }
        }

        return 0;
}

/**
 * em_dev_compute_costs() - Calculate cost values for new runtime EM table
 * @dev         : Device for which the EM table is to be updated
 * @table       : The new EM table that is going to get the costs calculated
 * @nr_states   : Number of performance states
 *
 * Calculate the em_perf_state::cost values for new runtime EM table. The
 * values are used for EAS during task placement. It also calculates and sets
 * the efficiency flag for each performance state. When the function finish
 * successfully the EM table is ready to be updated and used by EAS.
 *
 * Return 0 on success or a proper error in case of failure.
 */
int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
                         int nr_states)
{
        return em_compute_costs(dev, table, NULL, nr_states, 0);
}

/**
 * em_dev_update_perf_domain() - Update runtime EM table for a device
 * @dev         : Device for which the EM is to be updated
 * @new_table   : The new EM table that is going to be used from now
 *
 * Update EM runtime modifiable table for the @dev using the provided @table.
 *
 * This function uses a mutex to serialize writers, so it must not be called
 * from a non-sleeping context.
 *
 * Return 0 on success or an error code on failure.
 */
int em_dev_update_perf_domain(struct device *dev,
                              struct em_perf_table *new_table)
{
        struct em_perf_table *old_table;
        struct em_perf_domain *pd;

        if (!dev)
                return -EINVAL;

        /* Serialize update/unregister or concurrent updates */
        mutex_lock(&em_pd_mutex);

        if (!dev->em_pd) {
                mutex_unlock(&em_pd_mutex);
                return -EINVAL;
        }
        pd = dev->em_pd;

        kref_get(&new_table->kref);

        old_table = rcu_dereference_protected(pd->em_table,
                                              lockdep_is_held(&em_pd_mutex));
        rcu_assign_pointer(pd->em_table, new_table);

        em_cpufreq_update_efficiencies(dev, new_table->state);

        em_table_free(old_table);

        mutex_unlock(&em_pd_mutex);

        em_notify_pd_updated(pd);
        return 0;
}
EXPORT_SYMBOL_GPL(em_dev_update_perf_domain);

static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd,
                                struct em_perf_state *table,
                                const struct em_data_callback *cb,
                                unsigned long flags)
{
        unsigned long power, freq, prev_freq = 0;
        int nr_states = pd->nr_perf_states;
        int i, ret;

        /* Build the list of performance states for this performance domain */
        for (i = 0, freq = 0; i < nr_states; i++, freq++) {
                /*
                 * active_power() is a driver callback which ceils 'freq' to
                 * lowest performance state of 'dev' above 'freq' and updates
                 * 'power' and 'freq' accordingly.
                 */
                ret = cb->active_power(dev, &power, &freq);
                if (ret) {
                        dev_err(dev, "EM: invalid perf. state: %d\n",
                                ret);
                        return -EINVAL;
                }

                /*
                 * We expect the driver callback to increase the frequency for
                 * higher performance states.
                 */
                if (freq <= prev_freq) {
                        dev_err(dev, "EM: non-increasing freq: %lu\n",
                                freq);
                        return -EINVAL;
                }

                /*
                 * The power returned by active_state() is expected to be
                 * positive and be in range.
                 */
                if (!power || power > EM_MAX_POWER) {
                        dev_err(dev, "EM: invalid power: %lu\n",
                                power);
                        return -EINVAL;
                }

                table[i].power = power;
                table[i].frequency = prev_freq = freq;
        }

        em_init_performance(dev, pd, table, nr_states);

        ret = em_compute_costs(dev, table, cb, nr_states, flags);
        if (ret)
                return -EINVAL;

        return 0;
}

static int em_create_pd(struct device *dev, int nr_states,
                        const struct em_data_callback *cb,
                        const cpumask_t *cpus,
                        unsigned long flags)
{
        struct em_perf_table *em_table;
        struct em_perf_domain *pd;
        struct device *cpu_dev;
        int cpu, ret, num_cpus, id;

        if (_is_cpu_device(dev)) {
                num_cpus = cpumask_weight(cpus);

                /* Prevent max possible energy calculation to not overflow */
                if (num_cpus > EM_MAX_NUM_CPUS) {
                        dev_err(dev, "EM: too many CPUs, overflow possible\n");
                        return -EINVAL;
                }

                pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL);
                if (!pd)
                        return -ENOMEM;

                cpumask_copy(em_span_cpus(pd), cpus);
        } else {
                pd = kzalloc_obj(*pd);
                if (!pd)
                        return -ENOMEM;
        }

        pd->nr_perf_states = nr_states;

        INIT_LIST_HEAD(&pd->node);

        id = ida_alloc(&em_pd_ida, GFP_KERNEL);
        if (id < 0) {
                kfree(pd);
                return id;
        }
        pd->id = id;

        em_table = em_table_alloc(pd);
        if (!em_table)
                goto free_pd;

        ret = em_create_perf_table(dev, pd, em_table->state, cb, flags);
        if (ret)
                goto free_pd_table;

        rcu_assign_pointer(pd->em_table, em_table);

        if (_is_cpu_device(dev))
                for_each_cpu(cpu, cpus) {
                        cpu_dev = get_cpu_device(cpu);
                        cpu_dev->em_pd = pd;
                }

        dev->em_pd = pd;

        return 0;

free_pd_table:
        kfree(em_table);
free_pd:
        kfree(pd);
        ida_free(&em_pd_ida, id);
        return -EINVAL;
}

static void
em_cpufreq_update_efficiencies(struct device *dev, struct em_perf_state *table)
{
        struct em_perf_domain *pd = dev->em_pd;
        struct cpufreq_policy *policy;
        int found = 0;
        int i, cpu;

        if (!_is_cpu_device(dev))
                return;

        /* Try to get a CPU which is active and in this PD */
        cpu = cpumask_first_and(em_span_cpus(pd), cpu_active_mask);
        if (cpu >= nr_cpu_ids) {
                dev_warn(dev, "EM: No online CPU for CPUFreq policy\n");
                return;
        }

        policy = cpufreq_cpu_get(cpu);
        if (!policy) {
                dev_warn(dev, "EM: Access to CPUFreq policy failed\n");
                return;
        }

        for (i = 0; i < pd->nr_perf_states; i++) {
                if (!(table[i].flags & EM_PERF_STATE_INEFFICIENT))
                        continue;

                if (!cpufreq_table_set_inefficient(policy, table[i].frequency))
                        found++;
        }

        cpufreq_cpu_put(policy);

        if (!found)
                return;

        /*
         * Efficiencies have been installed in CPUFreq, inefficient frequencies
         * will be skipped. The EM can do the same.
         */
        pd->flags |= EM_PERF_DOMAIN_SKIP_INEFFICIENCIES;
}

/**
 * em_pd_get() - Return the performance domain for a device
 * @dev : Device to find the performance domain for
 *
 * Returns the performance domain to which @dev belongs, or NULL if it doesn't
 * exist.
 */
struct em_perf_domain *em_pd_get(struct device *dev)
{
        if (IS_ERR_OR_NULL(dev))
                return NULL;

        return dev->em_pd;
}
EXPORT_SYMBOL_GPL(em_pd_get);

/**
 * em_cpu_get() - Return the performance domain for a CPU
 * @cpu : CPU to find the performance domain for
 *
 * Returns the performance domain to which @cpu belongs, or NULL if it doesn't
 * exist.
 */
struct em_perf_domain *em_cpu_get(int cpu)
{
        struct device *cpu_dev;

        cpu_dev = get_cpu_device(cpu);
        if (!cpu_dev)
                return NULL;

        return em_pd_get(cpu_dev);
}
EXPORT_SYMBOL_GPL(em_cpu_get);

/**
 * em_dev_register_perf_domain() - Register the Energy Model (EM) for a device
 * @dev         : Device for which the EM is to register
 * @nr_states   : Number of performance states to register
 * @cb          : Callback functions providing the data of the Energy Model
 * @cpus        : Pointer to cpumask_t, which in case of a CPU device is
 *              obligatory. It can be taken from i.e. 'policy->cpus'. For other
 *              type of devices this should be set to NULL.
 * @microwatts  : Flag indicating that the power values are in micro-Watts or
 *              in some other scale. It must be set properly.
 *
 * Create Energy Model tables for a performance domain using the callbacks
 * defined in cb.
 *
 * The @microwatts is important to set with correct value. Some kernel
 * sub-systems might rely on this flag and check if all devices in the EM are
 * using the same scale.
 *
 * If multiple clients register the same performance domain, all but the first
 * registration will be ignored.
 *
 * Return 0 on success
 */
int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
                                const struct em_data_callback *cb,
                                const cpumask_t *cpus, bool microwatts)
{
        int ret = em_dev_register_pd_no_update(dev, nr_states, cb, cpus, microwatts);

        if (_is_cpu_device(dev))
                em_check_capacity_update();

        return ret;
}
EXPORT_SYMBOL_GPL(em_dev_register_perf_domain);

/**
 * em_dev_register_pd_no_update() - Register a perf domain for a device
 * @dev : Device to register the PD for
 * @nr_states : Number of performance states in the new PD
 * @cb : Callback functions for populating the energy model
 * @cpus : CPUs to include in the new PD (mandatory if @dev is a CPU device)
 * @microwatts : Whether or not the power values in the EM will be in uW
 *
 * Like em_dev_register_perf_domain(), but does not trigger a CPU capacity
 * update after registering the PD, even if @dev is a CPU device.
 */
int em_dev_register_pd_no_update(struct device *dev, unsigned int nr_states,
                                 const struct em_data_callback *cb,
                                 const cpumask_t *cpus, bool microwatts)
{
        struct em_perf_table *em_table;
        unsigned long cap, prev_cap = 0;
        unsigned long flags = 0;
        int cpu, ret;

        if (!dev || !nr_states || !cb)
                return -EINVAL;

        /*
         * Use a mutex to serialize the registration of performance domains and
         * let the driver-defined callback functions sleep.
         */
        mutex_lock(&em_pd_mutex);

        if (dev->em_pd) {
                ret = -EEXIST;
                goto unlock;
        }

        if (_is_cpu_device(dev)) {
                if (!cpus) {
                        dev_err(dev, "EM: invalid CPU mask\n");
                        ret = -EINVAL;
                        goto unlock;
                }

                for_each_cpu(cpu, cpus) {
                        if (em_cpu_get(cpu)) {
                                dev_err(dev, "EM: exists for CPU%d\n", cpu);
                                ret = -EEXIST;
                                goto unlock;
                        }
                        /*
                         * All CPUs of a domain must have the same
                         * micro-architecture since they all share the same
                         * table.
                         */
                        cap = arch_scale_cpu_capacity(cpu);
                        if (prev_cap && prev_cap != cap) {
                                dev_err(dev, "EM: CPUs of %*pbl must have the same capacity\n",
                                        cpumask_pr_args(cpus));

                                ret = -EINVAL;
                                goto unlock;
                        }
                        prev_cap = cap;
                }
        }

        if (microwatts)
                flags |= EM_PERF_DOMAIN_MICROWATTS;
        else if (cb->get_cost)
                flags |= EM_PERF_DOMAIN_ARTIFICIAL;

        /*
         * EM only supports uW (exception is artificial EM).
         * Therefore, check and force the drivers to provide
         * power in uW.
         */
        if (!microwatts && !(flags & EM_PERF_DOMAIN_ARTIFICIAL)) {
                dev_err(dev, "EM: only supports uW power values\n");
                ret = -EINVAL;
                goto unlock;
        }

        ret = em_create_pd(dev, nr_states, cb, cpus, flags);
        if (ret)
                goto unlock;

        dev->em_pd->flags |= flags;
        dev->em_pd->min_perf_state = 0;
        dev->em_pd->max_perf_state = nr_states - 1;

        em_table = rcu_dereference_protected(dev->em_pd->em_table,
                                             lockdep_is_held(&em_pd_mutex));
        em_cpufreq_update_efficiencies(dev, em_table->state);

        em_debug_create_pd(dev);
        dev_info(dev, "EM: created perf domain\n");

unlock:
        mutex_unlock(&em_pd_mutex);
        if (ret)
                return ret;

        mutex_lock(&em_pd_list_mutex);
        list_add_tail(&dev->em_pd->node, &em_pd_list);
        mutex_unlock(&em_pd_list_mutex);

        em_notify_pd_created(dev->em_pd);

        return 0;
}
EXPORT_SYMBOL_GPL(em_dev_register_pd_no_update);

/**
 * em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for a device
 * @dev         : Device for which the EM is registered
 *
 * Unregister the EM for the specified @dev (but not a CPU device).
 */
void em_dev_unregister_perf_domain(struct device *dev)
{
        if (IS_ERR_OR_NULL(dev) || !dev->em_pd)
                return;

        if (_is_cpu_device(dev))
                return;

        mutex_lock(&em_pd_list_mutex);
        list_del_init(&dev->em_pd->node);
        mutex_unlock(&em_pd_list_mutex);

        em_notify_pd_deleted(dev->em_pd);

        /*
         * The mutex separates all register/unregister requests and protects
         * from potential clean-up/setup issues in the debugfs directories.
         * The debugfs directory name is the same as device's name.
         */
        mutex_lock(&em_pd_mutex);
        em_debug_remove_pd(dev);

        em_table_free(rcu_dereference_protected(dev->em_pd->em_table,
                                                lockdep_is_held(&em_pd_mutex)));

        ida_free(&em_pd_ida, dev->em_pd->id);

        kfree(dev->em_pd);
        dev->em_pd = NULL;
        mutex_unlock(&em_pd_mutex);
}
EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain);

static struct em_perf_table *em_table_dup(struct em_perf_domain *pd)
{
        struct em_perf_table *em_table;
        struct em_perf_state *ps, *new_ps;
        int ps_size;

        em_table = em_table_alloc(pd);
        if (!em_table)
                return NULL;

        new_ps = em_table->state;

        rcu_read_lock();
        ps = em_perf_state_from_pd(pd);
        /* Initialize data based on old table */
        ps_size = sizeof(struct em_perf_state) * pd->nr_perf_states;
        memcpy(new_ps, ps, ps_size);

        rcu_read_unlock();

        return em_table;
}

static int em_recalc_and_update(struct device *dev, struct em_perf_domain *pd,
                                struct em_perf_table *em_table)
{
        int ret;

        if (!em_is_artificial(pd)) {
                ret = em_compute_costs(dev, em_table->state, NULL,
                                       pd->nr_perf_states, pd->flags);
                if (ret)
                        goto free_em_table;
        }

        ret = em_dev_update_perf_domain(dev, em_table);
        if (ret)
                goto free_em_table;

        /*
         * This is one-time-update, so give up the ownership in this updater.
         * The EM framework has incremented the usage counter and from now
         * will keep the reference (then free the memory when needed).
         */
free_em_table:
        em_table_free(em_table);
        return ret;
}

/*
 * Adjustment of CPU performance values after boot, when all CPUs capacites
 * are correctly calculated.
 */
static void em_adjust_new_capacity(unsigned int cpu, struct device *dev,
                                   struct em_perf_domain *pd)
{
        unsigned long cpu_capacity = arch_scale_cpu_capacity(cpu);
        struct em_perf_table *em_table;
        struct em_perf_state *table;
        unsigned long em_max_perf;

        rcu_read_lock();
        table = em_perf_state_from_pd(pd);
        em_max_perf = table[pd->nr_perf_states - 1].performance;
        rcu_read_unlock();

        if (em_max_perf == cpu_capacity)
                return;

        pr_debug("updating cpu%d cpu_cap=%lu old capacity=%lu\n", cpu,
                 cpu_capacity, em_max_perf);

        em_table = em_table_dup(pd);
        if (!em_table) {
                dev_warn(dev, "EM: allocation failed\n");
                return;
        }

        em_init_performance(dev, pd, em_table->state, pd->nr_perf_states);

        em_recalc_and_update(dev, pd, em_table);
}

/**
 * em_adjust_cpu_capacity() - Adjust the EM for a CPU after a capacity update.
 * @cpu: Target CPU.
 *
 * Adjust the existing EM for @cpu after a capacity update under the assumption
 * that the capacity has been updated in the same way for all of the CPUs in
 * the same perf domain.
 */
void em_adjust_cpu_capacity(unsigned int cpu)
{
        struct device *dev = get_cpu_device(cpu);
        struct em_perf_domain *pd;

        pd = em_pd_get(dev);
        if (pd)
                em_adjust_new_capacity(cpu, dev, pd);
}

static void em_check_capacity_update(void)
{
        cpumask_var_t cpu_done_mask;
        int cpu, failed_cpus = 0;

        if (!zalloc_cpumask_var(&cpu_done_mask, GFP_KERNEL)) {
                pr_warn("no free memory\n");
                return;
        }

        /* Check if CPUs capacity has changed than update EM */
        for_each_possible_cpu(cpu) {
                struct cpufreq_policy *policy;
                struct em_perf_domain *pd;
                struct device *dev;

                if (cpumask_test_cpu(cpu, cpu_done_mask))
                        continue;

                policy = cpufreq_cpu_get(cpu);
                if (!policy) {
                        failed_cpus++;
                        continue;
                }
                cpufreq_cpu_put(policy);

                dev = get_cpu_device(cpu);
                pd = em_pd_get(dev);
                if (!pd || em_is_artificial(pd))
                        continue;

                cpumask_or(cpu_done_mask, cpu_done_mask,
                           em_span_cpus(pd));

                em_adjust_new_capacity(cpu, dev, pd);
        }

        if (failed_cpus)
                schedule_delayed_work(&em_update_work, msecs_to_jiffies(1000));

        free_cpumask_var(cpu_done_mask);
}

static void em_update_workfn(struct work_struct *work)
{
        em_check_capacity_update();
}

/**
 * em_dev_update_chip_binning() - Update Energy Model after the new voltage
 *                              information is present in the OPPs.
 * @dev         : Device for which the Energy Model has to be updated.
 *
 * This function allows to update easily the EM with new values available in
 * the OPP framework and DT. It can be used after the chip has been properly
 * verified by device drivers and the voltages adjusted for the 'chip binning'.
 */
int em_dev_update_chip_binning(struct device *dev)
{
        struct em_perf_table *em_table;
        struct em_perf_domain *pd;
        int i, ret;

        if (IS_ERR_OR_NULL(dev))
                return -EINVAL;

        pd = em_pd_get(dev);
        if (!pd) {
                dev_warn(dev, "Couldn't find Energy Model\n");
                return -EINVAL;
        }

        em_table = em_table_dup(pd);
        if (!em_table) {
                dev_warn(dev, "EM: allocation failed\n");
                return -ENOMEM;
        }

        /* Update power values which might change due to new voltage in OPPs */
        for (i = 0; i < pd->nr_perf_states; i++) {
                unsigned long freq = em_table->state[i].frequency;
                unsigned long power;

                ret = dev_pm_opp_calc_power(dev, &power, &freq);
                if (ret) {
                        em_table_free(em_table);
                        return ret;
                }

                em_table->state[i].power = power;
        }

        return em_recalc_and_update(dev, pd, em_table);
}
EXPORT_SYMBOL_GPL(em_dev_update_chip_binning);


/**
 * em_update_performance_limits() - Update Energy Model with performance
 *                              limits information.
 * @pd                  : Performance Domain with EM that has to be updated.
 * @freq_min_khz        : New minimum allowed frequency for this device.
 * @freq_max_khz        : New maximum allowed frequency for this device.
 *
 * This function allows to update the EM with information about available
 * performance levels. It takes the minimum and maximum frequency in kHz
 * and does internal translation to performance levels.
 * Returns 0 on success or -EINVAL when failed.
 */
int em_update_performance_limits(struct em_perf_domain *pd,
                unsigned long freq_min_khz, unsigned long freq_max_khz)
{
        struct em_perf_state *table;
        int min_ps = -1;
        int max_ps = -1;
        int i;

        if (!pd)
                return -EINVAL;

        rcu_read_lock();
        table = em_perf_state_from_pd(pd);

        for (i = 0; i < pd->nr_perf_states; i++) {
                if (freq_min_khz == table[i].frequency)
                        min_ps = i;
                if (freq_max_khz == table[i].frequency)
                        max_ps = i;
        }
        rcu_read_unlock();

        /* Only update when both are found and sane */
        if (min_ps < 0 || max_ps < 0 || max_ps < min_ps)
                return -EINVAL;


        /* Guard simultaneous updates and make them atomic */
        mutex_lock(&em_pd_mutex);
        pd->min_perf_state = min_ps;
        pd->max_perf_state = max_ps;
        mutex_unlock(&em_pd_mutex);

        return 0;
}
EXPORT_SYMBOL_GPL(em_update_performance_limits);

static void rebuild_sd_workfn(struct work_struct *work)
{
        rebuild_sched_domains_energy();
}

void em_rebuild_sched_domains(void)
{
        static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);

        /*
         * When called from the cpufreq_register_driver() path, the
         * cpu_hotplug_lock is already held, so use a work item to
         * avoid nested locking in rebuild_sched_domains().
         */
        schedule_work(&rebuild_sd_work);
}

#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_NET)
int for_each_em_perf_domain(int (*cb)(struct em_perf_domain*, void *),
                            void *data)
{
        struct em_perf_domain *pd;

        lockdep_assert_not_held(&em_pd_mutex);
        guard(mutex)(&em_pd_list_mutex);

        list_for_each_entry(pd, &em_pd_list, node) {
                int ret;

                ret = cb(pd, data);
                if (ret)
                        return ret;
        }

        return 0;
}

struct em_perf_domain *em_perf_domain_get_by_id(int id)
{
        struct em_perf_domain *pd;

        lockdep_assert_not_held(&em_pd_mutex);
        guard(mutex)(&em_pd_list_mutex);

        list_for_each_entry(pd, &em_pd_list, node) {
                if (pd->id == id)
                        return pd;
        }

        return NULL;
}
#endif