cpufreq: helpers for walking the frequency table

Two new functions for getting the next higher and next lower frequencies
in the cpufreq table, based upon a frequency supplied in kHz.

This is useful for cpufreq governors that do not target frequencies
based upon a percentage or a pre-determined value, but instead access
the cpufreq table directly.

Signed-off-by: Mike Turquette <mturquette@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index 90431cb..54c4de4 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/cpufreq.h>
+#include <linux/err.h>
 
 /*********************************************************************
  *                     FREQUENCY TABLE HELPERS                       *
@@ -171,6 +172,78 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 }
 EXPORT_SYMBOL_GPL(cpufreq_frequency_table_target);
 
+int cpufreq_frequency_table_next_lowest(struct cpufreq_policy *policy,
+		struct cpufreq_frequency_table *table, int *index)
+{
+	unsigned int cur_freq;
+	unsigned int next_lowest_freq;
+	int optimal_index = -1;
+	int i = 0;
+
+	if (!policy || IS_ERR(policy) || !table || IS_ERR(table) ||
+			!index || IS_ERR(index))
+		return -ENOMEM;
+
+	cur_freq = policy->cur;
+	next_lowest_freq = policy->min;
+
+	/* we're at the lowest frequency in the table already, bail out */
+	if (cur_freq == policy->min)
+		return -EINVAL;
+
+	/* walk the list, find closest freq to cur_freq that is below it */
+	while(table[i].frequency != CPUFREQ_TABLE_END) {
+		if (table[i].frequency < cur_freq &&
+				table[i].frequency >= next_lowest_freq) {
+			next_lowest_freq = table[i].frequency;
+			optimal_index = table[i].index;
+		}
+
+		i++;
+	}
+
+	*index = optimal_index;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_next_lowest);
+
+int cpufreq_frequency_table_next_highest(struct cpufreq_policy *policy,
+		struct cpufreq_frequency_table *table, int *index)
+{
+	unsigned int cur_freq;
+	unsigned int next_higher_freq;
+	int optimal_index = -1;
+	int i = 0;
+
+	if (!policy || IS_ERR(policy) || !table || IS_ERR(table) ||
+			!index || IS_ERR(index))
+		return -ENOMEM;
+
+	cur_freq = policy->cur;
+	next_higher_freq = policy->max;
+
+	/* we're at the highest frequency in the table already, bail out */
+	if (cur_freq == policy->max)
+		return -EINVAL;
+
+	/* walk the list, find closest freq to cur_freq that is above it */
+	while(table[i].frequency != CPUFREQ_TABLE_END) {
+		if (table[i].frequency > cur_freq &&
+				table[i].frequency <= next_higher_freq) {
+			next_higher_freq = table[i].frequency;
+			optimal_index = table[i].index;
+		}
+
+		i++;
+	}
+
+	*index = optimal_index;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_next_highest);
+
 static DEFINE_PER_CPU(struct cpufreq_frequency_table *, cpufreq_show_table);
 /**
  * show_available_freqs - show available frequencies for the specified CPU