/*
   *  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/cpu.h>
  #include <linux/cpufreq.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/cputime.h>
  
  static spinlock_t cpufreq_stats_lock;
  
  struct cpufreq_stats {
  	unsigned int total_trans;
  	unsigned long long last_time;
  	unsigned int max_state;
  	unsigned int state_num;
  	unsigned int last_index;
  	u64 *time_in_state;
  	unsigned int *freq_table;
  #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
  	unsigned int *trans_table;
  #endif
  };
  
  static int cpufreq_stats_update(struct cpufreq_stats *stats)
  {
  	unsigned long long cur_time = get_jiffies_64();
  
  	spin_lock(&cpufreq_stats_lock);
  	stats->time_in_state[stats->last_index] += cur_time - stats->last_time;
  	stats->last_time = cur_time;
  	spin_unlock(&cpufreq_stats_lock);
  	return 0;
  }
  
  static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
  {
  	return sprintf(buf, "%d
  ", policy->stats->total_trans);
  }
  
  static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
  {
  	struct cpufreq_stats *stats = policy->stats;
  	ssize_t len = 0;
  	int i;
  
  	cpufreq_stats_update(stats);
  	for (i = 0; i < stats->state_num; i++) {
  		len += sprintf(buf + len, "%u %llu
  ", stats->freq_table[i],
  			(unsigned long long)
  			jiffies_64_to_clock_t(stats->time_in_state[i]));
  	}
  	return len;
  }
  
  #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
  static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
  {
  	struct cpufreq_stats *stats = policy->stats;
  	ssize_t len = 0;
  	int i, j;
  
  	len += snprintf(buf + len, PAGE_SIZE - len, "   From  :    To
  ");
  	len += snprintf(buf + len, PAGE_SIZE - len, "         : ");
  	for (i = 0; i < stats->state_num; i++) {
  		if (len >= PAGE_SIZE)
  			break;
  		len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
  				stats->freq_table[i]);
  	}
  	if (len >= PAGE_SIZE)
  		return PAGE_SIZE;
  
  	len += snprintf(buf + len, PAGE_SIZE - len, "
  ");
  
  	for (i = 0; i < stats->state_num; i++) {
  		if (len >= PAGE_SIZE)
  			break;
  
  		len += snprintf(buf + len, PAGE_SIZE - len, "%9u: ",
  				stats->freq_table[i]);
  
  		for (j = 0; j < stats->state_num; j++) {
  			if (len >= PAGE_SIZE)
  				break;
  			len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
  					stats->trans_table[i*stats->max_state+j]);
  		}
  		if (len >= PAGE_SIZE)
  			break;
  		len += snprintf(buf + len, PAGE_SIZE - len, "
  ");
  	}
  	if (len >= PAGE_SIZE)
  		return PAGE_SIZE;
  	return len;
  }
  cpufreq_freq_attr_ro(trans_table);
  #endif
  
  cpufreq_freq_attr_ro(total_trans);
  cpufreq_freq_attr_ro(time_in_state);
  
  static struct attribute *default_attrs[] = {
  	&total_trans.attr,
  	&time_in_state.attr,
  #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
  	&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 *stats, unsigned int freq)
  {
  	int index;
  	for (index = 0; index < stats->max_state; index++)
  		if (stats->freq_table[index] == freq)
  			return index;
  	return -1;
  }
  
  static void __cpufreq_stats_free_table(struct cpufreq_policy *policy)
  {
  	struct cpufreq_stats *stats = policy->stats;
  
  	/* Already freed */
  	if (!stats)
  		return;
  
  	pr_debug("%s: Free stats table
  ", __func__);
  
  	sysfs_remove_group(&policy->kobj, &stats_attr_group);
  	kfree(stats->time_in_state);
  	kfree(stats);
  	policy->stats = NULL;
  }
  
  static void cpufreq_stats_free_table(unsigned int cpu)
  {
  	struct cpufreq_policy *policy;
  
  	policy = cpufreq_cpu_get(cpu);
  	if (!policy)
  		return;
  
  	__cpufreq_stats_free_table(policy);
  
  	cpufreq_cpu_put(policy);
  }
  
  static int __cpufreq_stats_create_table(struct cpufreq_policy *policy)
  {
  	unsigned int i = 0, count = 0, ret = -ENOMEM;
  	struct cpufreq_stats *stats;
  	unsigned int alloc_size;
  	unsigned int cpu = policy->cpu;
  	struct cpufreq_frequency_table *pos, *table;
  
  	/* We need cpufreq table for creating stats table */
  	table = cpufreq_frequency_get_table(cpu);
  	if (unlikely(!table))
  		return 0;
  
  	/* stats already initialized */
  	if (policy->stats)
  		return -EEXIST;
  
  	stats = kzalloc(sizeof(*stats), GFP_KERNEL);
  	if (!stats)
  		return -ENOMEM;
  
  	/* Find total allocation size */
  	cpufreq_for_each_valid_entry(pos, table)
  		count++;
  
  	alloc_size = count * sizeof(int) + count * sizeof(u64);
  
  #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
  	alloc_size += count * count * sizeof(int);
  #endif
  
  	/* Allocate memory for time_in_state/freq_table/trans_table in one go */
  	stats->time_in_state = kzalloc(alloc_size, GFP_KERNEL);
  	if (!stats->time_in_state)
  		goto free_stat;
  
  	stats->freq_table = (unsigned int *)(stats->time_in_state + count);
  
  #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
  	stats->trans_table = stats->freq_table + count;
  #endif
  
  	stats->max_state = count;
  
  	/* Find valid-unique entries */
  	cpufreq_for_each_valid_entry(pos, table)
  		if (freq_table_get_index(stats, pos->frequency) == -1)
  			stats->freq_table[i++] = pos->frequency;
  
  	stats->state_num = i;
  	stats->last_time = get_jiffies_64();
  	stats->last_index = freq_table_get_index(stats, policy->cur);
  
  	policy->stats = stats;
  	ret = sysfs_create_group(&policy->kobj, &stats_attr_group);
  	if (!ret)
  		return 0;
  
  	/* We failed, release resources */
  	policy->stats = NULL;
  	kfree(stats->time_in_state);
  free_stat:
  	kfree(stats);
  
  	return ret;
  }
  
  static void cpufreq_stats_create_table(unsigned int cpu)
  {
  	struct cpufreq_policy *policy;
  
  	/*
  	 * "likely(!policy)" because normally cpufreq_stats will be registered
  	 * before cpufreq driver
  	 */
  	policy = cpufreq_cpu_get(cpu);
  	if (likely(!policy))
  		return;
  
  	__cpufreq_stats_create_table(policy);
  
  	cpufreq_cpu_put(policy);
  }
  
  static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
  		unsigned long val, void *data)
  {
  	int ret = 0;
  	struct cpufreq_policy *policy = data;
  
  	if (val == CPUFREQ_CREATE_POLICY)
  		ret = __cpufreq_stats_create_table(policy);
  	else if (val == CPUFREQ_REMOVE_POLICY)
  		__cpufreq_stats_free_table(policy);
  
  	return ret;
  }
  
  static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
  		unsigned long val, void *data)
  {
  	struct cpufreq_freqs *freq = data;
  	struct cpufreq_policy *policy = cpufreq_cpu_get(freq->cpu);
  	struct cpufreq_stats *stats;
  	int old_index, new_index;
  
  	if (!policy) {
  		pr_err("%s: No policy found
  ", __func__);
  		return 0;
  	}
  
  	if (val != CPUFREQ_POSTCHANGE)
  		goto put_policy;
  
  	if (!policy->stats) {
  		pr_debug("%s: No stats found
  ", __func__);
  		goto put_policy;
  	}
  
  	stats = policy->stats;
  
  	old_index = stats->last_index;
  	new_index = freq_table_get_index(stats, freq->new);
  
  	/* We can't do stats->time_in_state[-1]= .. */
  	if (old_index == -1 || new_index == -1)
  		goto put_policy;
  
  	if (old_index == new_index)
  		goto put_policy;
  
  	cpufreq_stats_update(stats);
  
  	stats->last_index = new_index;
  #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
  	stats->trans_table[old_index * stats->max_state + new_index]++;
  #endif
  	stats->total_trans++;
  
  put_policy:
  	cpufreq_cpu_put(policy);
  	return 0;
  }
  
  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;
  
  	for_each_online_cpu(cpu)
  		cpufreq_stats_create_table(cpu);
  
  	ret = cpufreq_register_notifier(&notifier_trans_block,
  				CPUFREQ_TRANSITION_NOTIFIER);
  	if (ret) {
  		cpufreq_unregister_notifier(&notifier_policy_block,
  				CPUFREQ_POLICY_NOTIFIER);
  		for_each_online_cpu(cpu)
  			cpufreq_stats_free_table(cpu);
  		return ret;
  	}
  
  	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);
  	for_each_online_cpu(cpu)
  		cpufreq_stats_free_table(cpu);
  }
  
  MODULE_AUTHOR("Zou Nan hai <nanhai.zou@intel.com>");
  MODULE_DESCRIPTION("Export cpufreq stats via sysfs");
  MODULE_LICENSE("GPL");
  
  module_init(cpufreq_stats_init);
  module_exit(cpufreq_stats_exit);