1 files changed, 290 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
new file mode 100644
index 000000000..6e57df7a2
--- /dev/null
+++ b/drivers/cpufreq/cpufreq_stats.c
@@ -0,0 +1,290 @@
+// 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 += scnprintf(buf + len, PAGE_SIZE - len, "   From  :    To\n");
+	len += scnprintf(buf + len, PAGE_SIZE - len, "         : ");
+	for (i = 0; i < stats->state_num; i++) {
+		if (len >= PAGE_SIZE - 1)
+			break;
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%9u ",
+				stats->freq_table[i]);
+	}
+	if (len >= PAGE_SIZE - 1)
+		return PAGE_SIZE - 1;
+
+	len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
+
+	for (i = 0; i < stats->state_num; i++) {
+		if (len >= PAGE_SIZE - 1)
+			break;
+
+		len += scnprintf(buf + len, PAGE_SIZE - 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 += scnprintf(buf + len, PAGE_SIZE - len, "%9u ", count);
+		}
+		if (len >= PAGE_SIZE - 1)
+			break;
+		len += scnprintf(buf + len, PAGE_SIZE - 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 (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++;
+}