cpufreq: Handle sorted frequency tables more efficiently

cpufreq drivers aren't required to provide a sorted frequency table
today, and even the ones which provide a sorted table aren't handled
efficiently by cpufreq core.

This patch adds infrastructure to verify if the freq-table provided by
the drivers is sorted or not, and use efficient helpers if they are
sorted.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 65 insertions, 8 deletions

diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index eac8bcb..3bbbf9e 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c
@@ -113,9 +113,9 @@ int cpufreq_generic_frequency_table_verify(struct cpufreq_policy *policy)
 }
 EXPORT_SYMBOL_GPL(cpufreq_generic_frequency_table_verify);
 
-int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
-				    unsigned int target_freq,
-				    unsigned int relation)
+int cpufreq_table_index_unsorted(struct cpufreq_policy *policy,
+				 unsigned int target_freq,
+				 unsigned int relation)
 {
 	struct cpufreq_frequency_table optimal = {
 		.driver_data = ~0,
@@ -205,7 +205,7 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 		 table[index].frequency);
 	return index;
 }
-EXPORT_SYMBOL_GPL(cpufreq_frequency_table_target);
+EXPORT_SYMBOL_GPL(cpufreq_table_index_unsorted);
 
 int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy,
 		unsigned int freq)
@@ -297,15 +297,72 @@ struct freq_attr *cpufreq_generic_attr[] = {
 };
 EXPORT_SYMBOL_GPL(cpufreq_generic_attr);
 
+static int set_freq_table_sorted(struct cpufreq_policy *policy)
+{
+	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
+	struct cpufreq_frequency_table *prev = NULL;
+	int ascending = 0;
+
+	policy->freq_table_sorted = CPUFREQ_TABLE_UNSORTED;
+
+	cpufreq_for_each_valid_entry(pos, table) {
+		if (!prev) {
+			prev = pos;
+			continue;
+		}
+
+		if (pos->frequency == prev->frequency) {
+			pr_warn("Duplicate freq-table entries: %u\n",
+				pos->frequency);
+			return -EINVAL;
+		}
+
+		/* Frequency increased from prev to pos */
+		if (pos->frequency > prev->frequency) {
+			/* But frequency was decreasing earlier */
+			if (ascending < 0) {
+				pr_debug("Freq table is unsorted\n");
+				return 0;
+			}
+
+			ascending++;
+		} else {
+			/* Frequency decreased from prev to pos */
+
+			/* But frequency was increasing earlier */
+			if (ascending > 0) {
+				pr_debug("Freq table is unsorted\n");
+				return 0;
+			}
+
+			ascending--;
+		}
+
+		prev = pos;
+	}
+
+	if (ascending > 0)
+		policy->freq_table_sorted = CPUFREQ_TABLE_SORTED_ASCENDING;
+	else
+		policy->freq_table_sorted = CPUFREQ_TABLE_SORTED_DESCENDING;
+
+	pr_debug("Freq table is sorted in %s order\n",
+		 ascending > 0 ? "ascending" : "descending");
+
+	return 0;
+}
+
 int cpufreq_table_validate_and_show(struct cpufreq_policy *policy,
 				      struct cpufreq_frequency_table *table)
 {
-	int ret = cpufreq_frequency_table_cpuinfo(policy, table);
+	int ret;
 
-	if (!ret)
-		policy->freq_table = table;
+	ret = cpufreq_frequency_table_cpuinfo(policy, table);
+	if (ret)
+		return ret;
 
-	return ret;
+	policy->freq_table = table;
+	return set_freq_table_sorted(policy);
 }
 EXPORT_SYMBOL_GPL(cpufreq_table_validate_and_show);