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Diffstat (limited to 'drivers/cpufreq/cpufreq_stats.c')
-rw-r--r--drivers/cpufreq/cpufreq_stats.c289
1 files changed, 289 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
new file mode 100644
index 0000000000..40a9ff18da
--- /dev/null
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -0,0 +1,289 @@
+// 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 - 1)
+ break;
+ len += sysfs_emit_at(buf, len, "%9u ", stats->freq_table[i]);
+ }
+ if (len >= PAGE_SIZE - 1)
+ return PAGE_SIZE - 1;
+
+ len += sysfs_emit_at(buf, len, "\n");
+
+ for (i = 0; i < stats->state_num; i++) {
+ if (len >= PAGE_SIZE - 1)
+ break;
+
+ len += sysfs_emit_at(buf, len, "%9u: ", stats->freq_table[i]);
+
+ for (j = 0; j < stats->state_num; j++) {
+ if (len >= PAGE_SIZE - 1)
+ 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 - 1)
+ break;
+ len += sysfs_emit_at(buf, len, "\n");
+ }
+
+ if (len >= PAGE_SIZE - 1) {
+ 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 (policy->freq_table_sorted != CPUFREQ_TABLE_UNSORTED ||
+ 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++;
+}