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cpufreq_stats.c

/*
 *  drivers/cpufreq/cpufreq_stats.c
 *
 *  Copyright (C) 2003-2004 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
 *          (C) 2004 Zou Nan hai <nanhai.zou@intel.com>.
 *
 * 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/sysdev.h>
#include <linux/cpu.h>
#include <linux/sysfs.h>
#include <linux/cpufreq.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 struct cpufreq_stats *cpufreq_stats_table[NR_CPUS];

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 = cpufreq_stats_table[cpu];
      if (stat->time_in_state)
            stat->time_in_state[stat->last_index] =
                  cputime64_add(stat->time_in_state[stat->last_index],
                              cputime_sub(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 = cpufreq_stats_table[policy->cpu];
      if (!stat)
            return 0;
      return sprintf(buf, "%d\n",
                  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 = 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 = 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 len;

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

static void cpufreq_stats_free_table(unsigned int cpu)
{
      struct cpufreq_stats *stat = cpufreq_stats_table[cpu];
      struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
      if (policy && policy->cpu == cpu)
            sysfs_remove_group(&policy->kobj, &stats_attr_group);
      if (stat) {
            kfree(stat->time_in_state);
            kfree(stat);
      }
      cpufreq_stats_table[cpu] = NULL;
      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 (cpufreq_stats_table[cpu])
            return -EBUSY;
      if ((stat = kzalloc(sizeof(struct cpufreq_stats), GFP_KERNEL)) == NULL)
            return -ENOMEM;

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

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

      stat->cpu = 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);
      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;
      if ((ret = cpufreq_stats_create_table(policy, table)))
            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 = cpufreq_stats_table[freq->cpu];
      if (!stat)
            return 0;

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

      cpufreq_stats_update(freq->cpu);
      if (old_index == new_index)
            return 0;

      if (old_index == -1 || new_index == -1)
            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_DEAD:
      case CPU_DEAD_FROZEN:
            cpufreq_stats_free_table(cpu);
            break;
      }
      return NOTIFY_OK;
}

static struct notifier_block cpufreq_stat_cpu_notifier __cpuinitdata =
{
      .notifier_call = cpufreq_stat_cpu_callback,
};

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

      if ((ret = cpufreq_register_notifier(&notifier_trans_block,
                        CPUFREQ_TRANSITION_NOTIFIER))) {
            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);
      }
}

MODULE_AUTHOR ("Zou Nan hai <nanhai.zou@intel.com>");
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);

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