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/*
 *  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;
	}