drm/nouveau: fix kernel-doc comments

[drm/drm-misc.git] / drivers / thermal / cpufreq_cooling.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/drivers/thermal/cpufreq_cooling.c
 *
 *  Copyright (C) 2012  Samsung Electronics Co., Ltd(http://www.samsung.com)
 *
 *  Copyright (C) 2012-2018 Linaro Limited.
 *
 *  Authors:    Amit Daniel <amit.kachhap@linaro.org>
 *              Viresh Kumar <viresh.kumar@linaro.org>
 *
 */
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/cpu_cooling.h>
#include <linux/device.h>
#include <linux/energy_model.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/pm_opp.h>
#include <linux/pm_qos.h>
#include <linux/slab.h>
#include <linux/thermal.h>
#include <linux/units.h>

#include "thermal_trace.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 time_in_idle - Idle time stats
 * @time: previous reading of the absolute time that this cpu was idle
 * @timestamp: wall time of the last invocation of get_cpu_idle_time_us()
 */
struct time_in_idle {
        u64 time;
        u64 timestamp;
};

/**
 * struct cpufreq_cooling_device - data for cooling device with cpufreq
 * @last_load: load measured by the latest call to cpufreq_get_requested_power()
 * @cpufreq_state: integer value representing the current state of cpufreq
 *      cooling devices.
 * @max_level: maximum cooling level. One less than total number of valid
 *      cpufreq frequencies.
 * @em: Reference on the Energy Model of the device
 * @cdev: thermal_cooling_device pointer to keep track of the
 *      registered cooling device.
 * @policy: cpufreq policy.
 * @cooling_ops: cpufreq callbacks to thermal cooling device ops
 * @idle_time: idle time stats
 * @qos_req: PM QoS contraint to apply
 *
 * This structure is required for keeping information of each registered
 * cpufreq_cooling_device.
 */
struct cpufreq_cooling_device {
        u32 last_load;
        unsigned int cpufreq_state;
        unsigned int max_level;
        struct em_perf_domain *em;
        struct cpufreq_policy *policy;
        struct thermal_cooling_device_ops cooling_ops;
#ifndef CONFIG_SMP
        struct time_in_idle *idle_time;
#endif
        struct freq_qos_request qos_req;
};

#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
/**
 * get_level: Find the level for a particular frequency
 * @cpufreq_cdev: cpufreq_cdev for which the property is required
 * @freq: Frequency
 *
 * Return: level corresponding to the frequency.
 */
static unsigned long get_level(struct cpufreq_cooling_device *cpufreq_cdev,
                               unsigned int freq)
{
        struct em_perf_state *table;
        int i;

        rcu_read_lock();
        table = em_perf_state_from_pd(cpufreq_cdev->em);
        for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
                if (freq > table[i].frequency)
                        break;
        }
        rcu_read_unlock();

        return cpufreq_cdev->max_level - i - 1;
}

static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_cdev,
                             u32 freq)
{
        struct em_perf_state *table;
        unsigned long power_mw;
        int i;

        rcu_read_lock();
        table = em_perf_state_from_pd(cpufreq_cdev->em);
        for (i = cpufreq_cdev->max_level - 1; i >= 0; i--) {
                if (freq > table[i].frequency)
                        break;
        }

        power_mw = table[i + 1].power;
        power_mw /= MICROWATT_PER_MILLIWATT;
        rcu_read_unlock();

        return power_mw;
}

static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
                             u32 power)
{
        struct em_perf_state *table;
        unsigned long em_power_mw;
        u32 freq;
        int i;

        rcu_read_lock();
        table = em_perf_state_from_pd(cpufreq_cdev->em);
        for (i = cpufreq_cdev->max_level; i > 0; i--) {
                /* Convert EM power to milli-Watts to make safe comparison */
                em_power_mw = table[i].power;
                em_power_mw /= MICROWATT_PER_MILLIWATT;
                if (power >= em_power_mw)
                        break;
        }
        freq = table[i].frequency;
        rcu_read_unlock();

        return freq;
}

/**
 * get_load() - get load for a cpu
 * @cpufreq_cdev: struct cpufreq_cooling_device for the cpu
 * @cpu: cpu number
 * @cpu_idx: index of the cpu in time_in_idle array
 *
 * Return: The average load of cpu @cpu in percentage since this
 * function was last called.
 */
#ifdef CONFIG_SMP
static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
                    int cpu_idx)
{
        unsigned long util = sched_cpu_util(cpu);

        return (util * 100) / arch_scale_cpu_capacity(cpu);
}
#else /* !CONFIG_SMP */
static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
                    int cpu_idx)
{
        u32 load;
        u64 now, now_idle, delta_time, delta_idle;
        struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu_idx];

        now_idle = get_cpu_idle_time(cpu, &now, 0);
        delta_idle = now_idle - idle_time->time;
        delta_time = now - idle_time->timestamp;

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

        idle_time->time = now_idle;
        idle_time->timestamp = now;

        return load;
}
#endif /* CONFIG_SMP */

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

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

/**
 * cpufreq_get_requested_power() - get the current power
 * @cdev:       &thermal_cooling_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, this function doesn't fail.
 */
static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
                                       u32 *power)
{
        unsigned long freq;
        int i = 0, cpu;
        u32 total_load = 0;
        struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
        struct cpufreq_policy *policy = cpufreq_cdev->policy;

        freq = cpufreq_quick_get(policy->cpu);

        for_each_cpu(cpu, policy->related_cpus) {
                u32 load;

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

                total_load += load;
        }

        cpufreq_cdev->last_load = total_load;

        *power = get_dynamic_power(cpufreq_cdev, freq);

        trace_thermal_power_cpu_get_power_simple(policy->cpu, *power);

        return 0;
}

/**
 * cpufreq_state2power() - convert a cpu cdev state to power consumed
 * @cdev:       &thermal_cooling_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 is bigger
 * than maximum allowed.
 */
static int cpufreq_state2power(struct thermal_cooling_device *cdev,
                               unsigned long state, u32 *power)
{
        struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
        unsigned int freq, num_cpus, idx;
        struct em_perf_state *table;

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

        num_cpus = cpumask_weight(cpufreq_cdev->policy->cpus);

        idx = cpufreq_cdev->max_level - state;

        rcu_read_lock();
        table = em_perf_state_from_pd(cpufreq_cdev->em);
        freq = table[idx].frequency;
        rcu_read_unlock();

        *power = cpu_freq_to_power(cpufreq_cdev, freq) * num_cpus;

        return 0;
}

/**
 * cpufreq_power2state() - convert power to a cooling device state
 * @cdev:       &thermal_cooling_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 CPUs load.  Calling this function with the same power
 * as input can yield different cooling device states depending on those
 * external factors.
 *
 * Return: 0 on success, this function doesn't fail.
 */
static int cpufreq_power2state(struct thermal_cooling_device *cdev,
                               u32 power, unsigned long *state)
{
        unsigned int target_freq;
        u32 last_load, normalised_power;
        struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;
        struct cpufreq_policy *policy = cpufreq_cdev->policy;

        last_load = cpufreq_cdev->last_load ?: 1;
        normalised_power = (power * 100) / last_load;
        target_freq = cpu_power_to_freq(cpufreq_cdev, normalised_power);

        *state = get_level(cpufreq_cdev, target_freq);
        trace_thermal_power_cpu_limit(policy->related_cpus, target_freq, *state,
                                      power);
        return 0;
}

static inline bool em_is_sane(struct cpufreq_cooling_device *cpufreq_cdev,
                              struct em_perf_domain *em) {
        struct cpufreq_policy *policy;
        unsigned int nr_levels;

        if (!em || em_is_artificial(em))
                return false;

        policy = cpufreq_cdev->policy;
        if (!cpumask_equal(policy->related_cpus, em_span_cpus(em))) {
                pr_err("The span of pd %*pbl is misaligned with cpufreq policy %*pbl\n",
                        cpumask_pr_args(em_span_cpus(em)),
                        cpumask_pr_args(policy->related_cpus));
                return false;
        }

        nr_levels = cpufreq_cdev->max_level + 1;
        if (em_pd_nr_perf_states(em) != nr_levels) {
                pr_err("The number of performance states in pd %*pbl (%u) doesn't match the number of cooling levels (%u)\n",
                        cpumask_pr_args(em_span_cpus(em)),
                        em_pd_nr_perf_states(em), nr_levels);
                return false;
        }

        return true;
}
#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */

#ifdef CONFIG_SMP
static inline int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
{
        return 0;
}

static inline void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
{
}
#else
static int allocate_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
{
        unsigned int num_cpus = cpumask_weight(cpufreq_cdev->policy->related_cpus);

        cpufreq_cdev->idle_time = kcalloc(num_cpus,
                                          sizeof(*cpufreq_cdev->idle_time),
                                          GFP_KERNEL);
        if (!cpufreq_cdev->idle_time)
                return -ENOMEM;

        return 0;
}

static void free_idle_time(struct cpufreq_cooling_device *cpufreq_cdev)
{
        kfree(cpufreq_cdev->idle_time);
        cpufreq_cdev->idle_time = NULL;
}
#endif /* CONFIG_SMP */

static unsigned int get_state_freq(struct cpufreq_cooling_device *cpufreq_cdev,
                                   unsigned long state)
{
        struct cpufreq_policy *policy;
        unsigned long idx;

#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
        /* Use the Energy Model table if available */
        if (cpufreq_cdev->em) {
                struct em_perf_state *table;
                unsigned int freq;

                idx = cpufreq_cdev->max_level - state;

                rcu_read_lock();
                table = em_perf_state_from_pd(cpufreq_cdev->em);
                freq = table[idx].frequency;
                rcu_read_unlock();

                return freq;
        }
#endif

        /* Otherwise, fallback on the CPUFreq table */
        policy = cpufreq_cdev->policy;
        if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
                idx = cpufreq_cdev->max_level - state;
        else
                idx = state;

        return policy->freq_table[idx].frequency;
}

/* 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, this function doesn't fail.
 */
static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
                                 unsigned long *state)
{
        struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;

        *state = cpufreq_cdev->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, this function doesn't fail.
 */
static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
                                 unsigned long *state)
{
        struct cpufreq_cooling_device *cpufreq_cdev = cdev->devdata;

        *state = cpufreq_cdev->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_cdev = cdev->devdata;
        unsigned int frequency;
        int ret;

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

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

        frequency = get_state_freq(cpufreq_cdev, state);

        ret = freq_qos_update_request(&cpufreq_cdev->qos_req, frequency);
        if (ret >= 0) {
                cpufreq_cdev->cpufreq_state = state;
                ret = 0;
        }

        return ret;
}

/**
 * __cpufreq_cooling_register - helper function to create cpufreq cooling device
 * @np: a valid struct device_node to the cooling device tree node
 * @policy: cpufreq policy
 * Normally this should be same as cpufreq policy->related_cpus.
 * @em: Energy Model of the cpufreq policy
 *
 * This interface function registers the cpufreq cooling device with the name
 * "cpufreq-%s". 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,
                        struct cpufreq_policy *policy,
                        struct em_perf_domain *em)
{
        struct thermal_cooling_device *cdev;
        struct cpufreq_cooling_device *cpufreq_cdev;
        unsigned int i;
        struct device *dev;
        int ret;
        struct thermal_cooling_device_ops *cooling_ops;
        char *name;

        if (IS_ERR_OR_NULL(policy)) {
                pr_err("%s: cpufreq policy isn't valid: %p\n", __func__, policy);
                return ERR_PTR(-EINVAL);
        }

        dev = get_cpu_device(policy->cpu);
        if (unlikely(!dev)) {
                pr_warn("No cpu device for cpu %d\n", policy->cpu);
                return ERR_PTR(-ENODEV);
        }

        i = cpufreq_table_count_valid_entries(policy);
        if (!i) {
                pr_debug("%s: CPUFreq table not found or has no valid entries\n",
                         __func__);
                return ERR_PTR(-ENODEV);
        }

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

        cpufreq_cdev->policy = policy;

        ret = allocate_idle_time(cpufreq_cdev);
        if (ret) {
                cdev = ERR_PTR(ret);
                goto free_cdev;
        }

        /* max_level is an index, not a counter */
        cpufreq_cdev->max_level = i - 1;

        cooling_ops = &cpufreq_cdev->cooling_ops;
        cooling_ops->get_max_state = cpufreq_get_max_state;
        cooling_ops->get_cur_state = cpufreq_get_cur_state;
        cooling_ops->set_cur_state = cpufreq_set_cur_state;

#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
        if (em_is_sane(cpufreq_cdev, em)) {
                cpufreq_cdev->em = em;
                cooling_ops->get_requested_power = cpufreq_get_requested_power;
                cooling_ops->state2power = cpufreq_state2power;
                cooling_ops->power2state = cpufreq_power2state;
        } else
#endif
        if (policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED) {
                pr_err("%s: unsorted frequency tables are not supported\n",
                       __func__);
                cdev = ERR_PTR(-EINVAL);
                goto free_idle_time;
        }

        ret = freq_qos_add_request(&policy->constraints,
                                   &cpufreq_cdev->qos_req, FREQ_QOS_MAX,
                                   get_state_freq(cpufreq_cdev, 0));
        if (ret < 0) {
                pr_err("%s: Failed to add freq constraint (%d)\n", __func__,
                       ret);
                cdev = ERR_PTR(ret);
                goto free_idle_time;
        }

        cdev = ERR_PTR(-ENOMEM);
        name = kasprintf(GFP_KERNEL, "cpufreq-%s", dev_name(dev));
        if (!name)
                goto remove_qos_req;

        cdev = thermal_of_cooling_device_register(np, name, cpufreq_cdev,
                                                  cooling_ops);
        kfree(name);

        if (IS_ERR(cdev))
                goto remove_qos_req;

        return cdev;

remove_qos_req:
        freq_qos_remove_request(&cpufreq_cdev->qos_req);
free_idle_time:
        free_idle_time(cpufreq_cdev);
free_cdev:
        kfree(cpufreq_cdev);
        return cdev;
}

/**
 * cpufreq_cooling_register - function to create cpufreq cooling device.
 * @policy: cpufreq policy
 *
 * This interface function registers the cpufreq cooling device with the name
 * "cpufreq-%s". 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(struct cpufreq_policy *policy)
{
        return __cpufreq_cooling_register(NULL, policy, NULL);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_register);

/**
 * of_cpufreq_cooling_register - function to create cpufreq cooling device.
 * @policy: cpufreq policy
 *
 * This interface function registers the cpufreq cooling device with the name
 * "cpufreq-%s". 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 the Energy Model (if present).  The cpus must have
 * registered their OPPs using the OPP library.
 *
 * Return: a valid struct thermal_cooling_device pointer on success,
 * and NULL on failure.
 */
struct thermal_cooling_device *
of_cpufreq_cooling_register(struct cpufreq_policy *policy)
{
        struct device_node *np = of_get_cpu_node(policy->cpu, NULL);
        struct thermal_cooling_device *cdev = NULL;

        if (!np) {
                pr_err("cpufreq_cooling: OF node not available for cpu%d\n",
                       policy->cpu);
                return NULL;
        }

        if (of_property_present(np, "#cooling-cells")) {
                struct em_perf_domain *em = em_cpu_get(policy->cpu);

                cdev = __cpufreq_cooling_register(np, policy, em);
                if (IS_ERR(cdev)) {
                        pr_err("cpufreq_cooling: cpu%d failed to register as cooling device: %ld\n",
                               policy->cpu, PTR_ERR(cdev));
                        cdev = NULL;
                }
        }

        of_node_put(np);
        return cdev;
}
EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);

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

        if (!cdev)
                return;

        cpufreq_cdev = cdev->devdata;

        thermal_cooling_device_unregister(cdev);
        freq_qos_remove_request(&cpufreq_cdev->qos_req);
        free_idle_time(cpufreq_cdev);
        kfree(cpufreq_cdev);
}
EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);