text: /*
   *  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), .owner = THIS_MODULE, \
  		.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 cpufreq_stat_cpu_callback(struct notifier_block *nfb,
  					unsigned long action, void *hcpu)
  {
  	unsigned int cpu = (unsigned long)hcpu;
  
  	switch (action) {
  	case CPU_ONLINE:
  		cpufreq_update_policy(cpu);
  		break;
  	case CPU_DEAD:
  		cpufreq_stats_free_table(cpu);
  		break;
  	}
  	return NOTIFY_OK;
  }
  
  static struct notifier_block cpufreq_stat_cpu_notifier =
  {
  	.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_stat_cpu_callback(&cpufreq_stat_cpu_notifier,
  				CPU_ONLINE, (void *)(long)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_stat_cpu_callback(&cpufreq_stat_cpu_notifier,
  						CPU_DEAD, (void *)(long)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);
  