// SPDX-License-Identifier: GPL-2.0-only
/*
* drivers/cpufreq/cpufreq_stats.c
*
* Copyright (C) 2003-2004 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
* (C) 2004 Zou Nan hai <nanhai.zou@intel.com>.
*/
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/sched/clock.h>
#include <linux/slab.h>
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;
unsigned int *trans_table;
/* Deferred reset */
unsigned int reset_pending;
unsigned long long reset_time;
};
static void cpufreq_stats_update(struct cpufreq_stats *stats,
unsigned long long time)
{
unsigned long long cur_time = local_clock();
stats->time_in_state[stats->last_index] += cur_time - time;
stats->last_time = cur_time;
}
static void cpufreq_stats_reset_table(struct cpufreq_stats *stats)
{
unsigned int count = stats->max_state;
memset(stats->time_in_state, 0, count * sizeof(u64));
memset(stats->trans_table, 0, count * count * sizeof(int));
stats->last_time = local_clock();
stats->total_trans = 0;
/* Adjust for the time elapsed since reset was requested */
WRITE_ONCE(stats->reset_pending, 0);
/*
* Prevent the reset_time read from being reordered before the
* reset_pending accesses in cpufreq_stats_record_transition().
*/
smp_rmb();
cpufreq_stats_update(stats, READ_ONCE(stats->reset_time));
}
static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
{
struct cpufreq_stats *stats = policy->stats;
if (READ_ONCE(stats->reset_pending))
return sprintf(buf, "%d\n", 0);
else
return sprintf(buf, "%u\n", stats->total_trans);
}
cpufreq_freq_attr_ro(total_trans);
static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
{
struct cpufreq_stats *stats = policy->stats;
bool pending = READ_ONCE(stats->reset_pending);
unsigned long long time;
ssize_t len = 0;
int i;
for (i = 0; i < stats->state_num; i++) {
if (pending) {
if (i == stats->last_index) {
/*
* Prevent the reset_time read from occurring
* before the reset_pending read above.
*/
smp_rmb();
time = local_clock() - READ_ONCE(stats->reset_time);
} else {
time = 0;
}
} else {
time = stats->time_in_state[i];
if (i == stats->last_index)
time += local_clock() - stats->last_time;
}
len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
nsec_to_clock_t(time));
}
return len;
}
cpufreq_freq_attr_ro(time_in_state);
/* We don't care what is written to the attribute */
static ssize_t store_reset(struct cpufreq_policy *policy, const char *buf,
size_t count)
{
struct cpufreq_stats *stats = policy->stats;
/*
* Defer resetting of stats to cpufreq_stats_record_transition() to
* avoid races.
*/
WRITE_ONCE(stats->reset_time, local_clock());
/*
* The memory barrier below is to prevent the readers of reset_time from
* seeing a stale or partially updated value.
*/
smp_wmb();
WRITE_ONCE(stats->reset_pending, 1);
return count;
}
cpufreq_freq_attr_wo(reset);
static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
{
struct cpufreq_stats *stats = policy->stats;
bool pending = READ_ONCE(stats->reset_pending);
ssize_t len = 0;
int i, j, count;
len += sysfs_emit_at(buf, len, " From : To\n");
len += sysfs_emit_at(buf, len, " : ");
for (i = 0; i < stats->state_num; i++) {
if (len >= PAGE_SIZE)
break;
len += sysfs_emit_at(buf, len, "%9u ", stats->freq_table[i]);
}
if (len >= PAGE_SIZE)
return PAGE_SIZE;
len += sysfs_emit_at(buf, len, "\n");
for (i = 0; i < stats->state_num; i++) {
if (len >= PAGE_SIZE)
break;
len += sysfs_emit_at(buf, len, "%9u: ", stats->freq_table[i]);
for (j = 0; j < stats->state_num; j++) {
if (len >= PAGE_SIZE)
break;
if (pending)
count = 0;
else
count = stats->trans_table[i * stats->max_state + j];
len += sysfs_emit_at(buf, len, "%9u ", count);
}
if (len >= PAGE_SIZE)
break;
len += sysfs_emit_at(buf, len, "\n");
}
if (len >= PAGE_SIZE) {
pr_warn_once("cpufreq transition table exceeds PAGE_SIZE. Disabling\n");
return -EFBIG;
}
return len;
}
cpufreq_freq_attr_ro(trans_table);
static struct attribute *default_attrs[] = {
&total_trans.attr,
&time_in_state.attr,
&reset.attr,
&trans_table.attr,
NULL
};
static const 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;
}
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\n", __func__);
sysfs_remove_group(&policy->kobj, &stats_attr_group);
kfree(stats->time_in_state);
kfree(stats);
policy->stats = NULL;
}
void cpufreq_stats_create_table(struct cpufreq_policy *policy)
{
unsigned int i = 0, count;
struct cpufreq_stats *stats;
unsigned int alloc_size;
struct cpufreq_frequency_table *pos;
count = cpufreq_table_count_valid_entries(policy);
if (!count)
return;
/* stats already initialized */
if (policy->stats)
return;
stats = kzalloc(sizeof(*stats), GFP_KERNEL);
if (!stats)
return;
alloc_size = count * sizeof(int) + count * sizeof(u64);
alloc_size += count * count * sizeof(int);
/* 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);
stats->trans_table = stats->freq_table + count;
stats->max_state = count;
/* Find valid-unique entries */
cpufreq_for_each_valid_entry(pos, policy->freq_table)
if (freq_table_get_index(stats, pos->frequency) == -1)
stats->freq_table[i++] = pos->frequency;
stats->state_num = i;
stats->last_time = local_clock();
stats->last_index = freq_table_get_index(stats, policy->cur);
policy->stats = stats;
if (!sysfs_create_group(&policy->kobj, &stats_attr_group))
return;
/* We failed, release resources */
policy->stats = NULL;
kfree(stats->time_in_state);
free_stat:
kfree(stats);
}
void cpufreq_stats_record_transition(struct cpufreq_policy *policy,
unsigned int new_freq)
{
struct cpufreq_stats *stats = policy->stats;
int old_index, new_index;
if (unlikely(!stats))
return;
if (unlikely(READ_ONCE(stats->reset_pending)))
cpufreq_stats_reset_table(stats);
old_index = stats->last_index;
new_index = freq_table_get_index(stats, new_freq);
/* We can't do stats->time_in_state[-1]= .. */
if (unlikely(old_index == -1 || new_index == -1 || old_index == new_index))
return;
cpufreq_stats_update(stats, stats->last_time);
stats->last_index = new_index;
stats->trans_table[old_index * stats->max_state + new_index]++;
stats->total_trans++;
}