cpufreq_stats.c

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/*
 *  drivers/cpufreq/cpufreq_stats.c
 *
 *  Copyright (C) 2003-2004 Venkatesh Pallipadi <[email protected]>.
 *  (C) 2004 Zou Nan hai <[email protected]>.
 *
 * 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.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/sysfs.h>
#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/jiffies.h>
#include <linux/percpu.h>
#include <linux/kobject.h>
#include <linux/spinlock.h>
#include <linux/notifier.h>
#include <asm/cputime.h>

static spinlock_t cpufreq_stats_lock;

#define CPUFREQ_STATDEVICE_ATTR(_name, _mode, _show) \
static struct freq_attr _attr_##_name = {\
    .attr = {.name = __stringify(_name), .mode = _mode, }, \
    .show = _show,\
};

struct cpufreq_stats {
    unsigned int cpu;
    unsigned int total_trans;
    unsigned long long  last_time;
    unsigned int max_state;
    unsigned int state_num;
    unsigned int last_index;
    cputime64_t *time_in_state;
    unsigned int *freq_table;
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
    unsigned int *trans_table;
#endif
};

static DEFINE_PER_CPU(struct cpufreq_stats *, cpufreq_stats_table);

struct cpufreq_stats_attribute {
    struct attribute attr;
    ssize_t(*show) (struct cpufreq_stats *, char *);
};

static int cpufreq_stats_update(unsigned int cpu)
{
    struct cpufreq_stats *stat;
    unsigned long long cur_time;

    cur_time = get_jiffies_64();
    spin_lock(&cpufreq_stats_lock);
    stat = per_cpu(cpufreq_stats_table, cpu);
    if (stat->time_in_state)
        stat->time_in_state[stat->last_index] +=
            cur_time - stat->last_time;
    stat->last_time = cur_time;
    spin_unlock(&cpufreq_stats_lock);
    return 0;
}

static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
{
    struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
    if (!stat)
        return 0;
    return sprintf(buf, "%d\n",
            per_cpu(cpufreq_stats_table, stat->cpu)->total_trans);
}

static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
{
    ssize_t len = 0;
    int i;
    struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
    if (!stat)
        return 0;
    cpufreq_stats_update(stat->cpu);
    for (i = 0; i < stat->state_num; i++) {
        len += sprintf(buf + len, "%u %llu\n", stat->freq_table[i],
            (unsigned long long)
            cputime64_to_clock_t(stat->time_in_state[i]));
    }
    return len;
}

#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
{
    ssize_t len = 0;
    int i, j;

    struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
    if (!stat)
        return 0;
    cpufreq_stats_update(stat->cpu);
    len += snprintf(buf + len, PAGE_SIZE - len, "   From  :    To\n");
    len += snprintf(buf + len, PAGE_SIZE - len, "         : ");
    for (i = 0; i < stat->state_num; i++) {
        if (len >= PAGE_SIZE)
            break;
        len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
                stat->freq_table[i]);
    }
    if (len >= PAGE_SIZE)
        return PAGE_SIZE;

    len += snprintf(buf + len, PAGE_SIZE - len, "\n");

    for (i = 0; i < stat->state_num; i++) {
        if (len >= PAGE_SIZE)
            break;

        len += snprintf(buf + len, PAGE_SIZE - len, "%9u: ",
                stat->freq_table[i]);

        for (j = 0; j < stat->state_num; j++)   {
            if (len >= PAGE_SIZE)
                break;
            len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
                    stat->trans_table[i*stat->max_state+j]);
        }
        if (len >= PAGE_SIZE)
            break;
        len += snprintf(buf + len, PAGE_SIZE - len, "\n");
    }
    if (len >= PAGE_SIZE)
        return PAGE_SIZE;
    return len;
}
CPUFREQ_STATDEVICE_ATTR(trans_table, 0444, show_trans_table);
#endif

CPUFREQ_STATDEVICE_ATTR(total_trans, 0444, show_total_trans);
CPUFREQ_STATDEVICE_ATTR(time_in_state, 0444, show_time_in_state);

static struct attribute *default_attrs[] = {
    &_attr_total_trans.attr,
    &_attr_time_in_state.attr,
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
    &_attr_trans_table.attr,
#endif
    NULL
};
static struct attribute_group stats_attr_group = {
    .attrs = default_attrs,
    .name = "stats"
};

static int freq_table_get_index(struct cpufreq_stats *stat, unsigned int freq)
{
    int index;
    for (index = 0; index < stat->max_state; index++)
        if (stat->freq_table[index] == freq)
            return index;
    return -1;
}

/* should be called late in the CPU removal sequence so that the stats
 * memory is still available in case someone tries to use it.
 */
static void cpufreq_stats_free_table(unsigned int cpu)
{
    struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, cpu);
    if (stat) {
        kfree(stat->time_in_state);
        kfree(stat);
    }
    per_cpu(cpufreq_stats_table, cpu) = NULL;
}

/* must be called early in the CPU removal sequence (before
 * cpufreq_remove_dev) so that policy is still valid.
 */
static void cpufreq_stats_free_sysfs(unsigned int cpu)
{
    struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
    if (policy && policy->cpu == cpu)
        sysfs_remove_group(&policy->kobj, &stats_attr_group);
    if (policy)
        cpufreq_cpu_put(policy);
}

static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
        struct cpufreq_frequency_table *table)
{
    unsigned int i, j, count = 0, ret = 0;
    struct cpufreq_stats *stat;
    struct cpufreq_policy *data;
    unsigned int alloc_size;
    unsigned int cpu = policy->cpu;
    if (per_cpu(cpufreq_stats_table, cpu))
        return -EBUSY;
    stat = kzalloc(sizeof(struct cpufreq_stats), GFP_KERNEL);
    if ((stat) == NULL)
        return -ENOMEM;

    data = cpufreq_cpu_get(cpu);
    if (data == NULL) {
        ret = -EINVAL;
        goto error_get_fail;
    }

    ret = sysfs_create_group(&data->kobj, &stats_attr_group);
    if (ret)
        goto error_out;

    stat->cpu = cpu;
    per_cpu(cpufreq_stats_table, cpu) = stat;

    for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
        unsigned int freq = table[i].frequency;
        if (freq == CPUFREQ_ENTRY_INVALID)
            continue;
        count++;
    }

    alloc_size = count * sizeof(int) + count * sizeof(cputime64_t);

#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
    alloc_size += count * count * sizeof(int);
#endif
    stat->max_state = count;
    stat->time_in_state = kzalloc(alloc_size, GFP_KERNEL);
    if (!stat->time_in_state) {
        ret = -ENOMEM;
        goto error_out;
    }
    stat->freq_table = (unsigned int *)(stat->time_in_state + count);

#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
    stat->trans_table = stat->freq_table + count;
#endif
    j = 0;
    for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
        unsigned int freq = table[i].frequency;
        if (freq == CPUFREQ_ENTRY_INVALID)
            continue;
        if (freq_table_get_index(stat, freq) == -1)
            stat->freq_table[j++] = freq;
    }
    stat->state_num = j;
    spin_lock(&cpufreq_stats_lock);
    stat->last_time = get_jiffies_64();
    stat->last_index = freq_table_get_index(stat, policy->cur);
    spin_unlock(&cpufreq_stats_lock);
    cpufreq_cpu_put(data);
    return 0;
error_out:
    cpufreq_cpu_put(data);
error_get_fail:
    kfree(stat);
    per_cpu(cpufreq_stats_table, cpu) = NULL;
    return ret;
}

static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
        unsigned long val, void *data)
{
    int ret;
    struct cpufreq_policy *policy = data;
    struct cpufreq_frequency_table *table;
    unsigned int cpu = policy->cpu;
    if (val != CPUFREQ_NOTIFY)
        return 0;
    table = cpufreq_frequency_get_table(cpu);
    if (!table)
        return 0;
    ret = cpufreq_stats_create_table(policy, table);
    if (ret)
        return ret;
    return 0;
}

static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
        unsigned long val, void *data)
{
    struct cpufreq_freqs *freq = data;
    struct cpufreq_stats *stat;
    int old_index, new_index;

    if (val != CPUFREQ_POSTCHANGE)
        return 0;

    stat = per_cpu(cpufreq_stats_table, freq->cpu);
    if (!stat)
        return 0;

    old_index = stat->last_index;
    new_index = freq_table_get_index(stat, freq->new);

    /* We can't do stat->time_in_state[-1]= .. */
    if (old_index == -1 || new_index == -1)
        return 0;

    cpufreq_stats_update(freq->cpu);

    if (old_index == new_index)
        return 0;

    spin_lock(&cpufreq_stats_lock);
    stat->last_index = new_index;
#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
    stat->trans_table[old_index * stat->max_state + new_index]++;
#endif
    stat->total_trans++;
    spin_unlock(&cpufreq_stats_lock);
    return 0;
}

static int __cpuinit cpufreq_stat_cpu_callback(struct notifier_block *nfb,
                           unsigned long action,
                           void *hcpu)
{
    unsigned int cpu = (unsigned long)hcpu;

    switch (action) {
    case CPU_ONLINE:
    case CPU_ONLINE_FROZEN:
        cpufreq_update_policy(cpu);
        break;
    case CPU_DOWN_PREPARE:
    case CPU_DOWN_PREPARE_FROZEN:
        cpufreq_stats_free_sysfs(cpu);
        break;
    case CPU_DEAD:
    case CPU_DEAD_FROZEN:
        cpufreq_stats_free_table(cpu);
        break;
    }
    return NOTIFY_OK;
}

/* priority=1 so this will get called before cpufreq_remove_dev */
static struct notifier_block cpufreq_stat_cpu_notifier __refdata = {
    .notifier_call = cpufreq_stat_cpu_callback,
    .priority = 1,
};

static struct notifier_block notifier_policy_block = {
    .notifier_call = cpufreq_stat_notifier_policy
};

static struct notifier_block notifier_trans_block = {
    .notifier_call = cpufreq_stat_notifier_trans
};

static int __init cpufreq_stats_init(void)
{
    int ret;
    unsigned int cpu;

    spin_lock_init(&cpufreq_stats_lock);
    ret = cpufreq_register_notifier(&notifier_policy_block,
                CPUFREQ_POLICY_NOTIFIER);
    if (ret)
        return ret;

    ret = cpufreq_register_notifier(&notifier_trans_block,
                CPUFREQ_TRANSITION_NOTIFIER);
    if (ret) {
        cpufreq_unregister_notifier(&notifier_policy_block,
                CPUFREQ_POLICY_NOTIFIER);
        return ret;
    }

    register_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
    for_each_online_cpu(cpu) {
        cpufreq_update_policy(cpu);
    }
    return 0;
}
static void __exit cpufreq_stats_exit(void)
{
    unsigned int cpu;

    cpufreq_unregister_notifier(&notifier_policy_block,
            CPUFREQ_POLICY_NOTIFIER);
    cpufreq_unregister_notifier(&notifier_trans_block,
            CPUFREQ_TRANSITION_NOTIFIER);
    unregister_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
    for_each_online_cpu(cpu) {
        cpufreq_stats_free_table(cpu);
        cpufreq_stats_free_sysfs(cpu);
    }
}

MODULE_AUTHOR("Zou Nan hai <[email protected]>");
MODULE_DESCRIPTION("'cpufreq_stats' - A driver to export cpufreq stats "
                "through sysfs filesystem");
MODULE_LICENSE("GPL");

module_init(cpufreq_stats_init);
module_exit(cpufreq_stats_exit);