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>

2 files changed, 296 insertions, 11 deletions

diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index eac8bcbdaad1..3bbbf9e6960c 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);
 
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index c378776628b4..c6410b1b2490 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -36,6 +36,12 @@
 
 struct cpufreq_governor;
 
+enum cpufreq_table_sorting {
+        CPUFREQ_TABLE_UNSORTED,
+        CPUFREQ_TABLE_SORTED_ASCENDING,
+        CPUFREQ_TABLE_SORTED_DESCENDING
+};
+
 struct cpufreq_freqs {
         unsigned int cpu;       /* cpu nr */
         unsigned int old;
@@ -87,6 +93,7 @@ struct cpufreq_policy {
 
         struct cpufreq_user_policy user_policy;
         struct cpufreq_frequency_table  *freq_table;
+        enum cpufreq_table_sorting freq_table_sorted;
 
         struct list_head        policy_list;
         struct kobject          kobj;
@@ -597,9 +604,9 @@ int cpufreq_frequency_table_verify(struct cpufreq_policy *policy,
                                    struct cpufreq_frequency_table *table);
 int cpufreq_generic_frequency_table_verify(struct cpufreq_policy *policy);
 
-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);
 int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy,
                 unsigned int freq);
 
@@ -610,6 +617,227 @@ int cpufreq_boost_trigger_state(int state);
 int cpufreq_boost_enabled(void);
 int cpufreq_enable_boost_support(void);
 bool policy_has_boost_freq(struct cpufreq_policy *policy);
+
+/* Find lowest freq at or above target in a table in ascending order */
+static inline int cpufreq_table_find_index_al(struct cpufreq_policy *policy,
+                                              unsigned int target_freq)
+{
+        struct cpufreq_frequency_table *table = policy->freq_table;
+        unsigned int freq;
+        int i, best = -1;
+
+        for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+                freq = table[i].frequency;
+
+                if (freq >= target_freq)
+                        return i;
+
+                best = i;
+        }
+
+        return best;
+}
+
+/* Find lowest freq at or above target in a table in descending order */
+static inline int cpufreq_table_find_index_dl(struct cpufreq_policy *policy,
+                                              unsigned int target_freq)
+{
+        struct cpufreq_frequency_table *table = policy->freq_table;
+        unsigned int freq;
+        int i, best = -1;
+
+        for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+                freq = table[i].frequency;
+
+                if (freq == target_freq)
+                        return i;
+
+                if (freq > target_freq) {
+                        best = i;
+                        continue;
+                }
+
+                /* No freq found above target_freq */
+                if (best == -1)
+                        return i;
+
+                return best;
+        }
+
+        return best;
+}
+
+/* Works only on sorted freq-tables */
+static inline int cpufreq_table_find_index_l(struct cpufreq_policy *policy,
+                                             unsigned int target_freq)
+{
+        target_freq = clamp_val(target_freq, policy->min, policy->max);
+
+        if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
+                return cpufreq_table_find_index_al(policy, target_freq);
+        else
+                return cpufreq_table_find_index_dl(policy, target_freq);
+}
+
+/* Find highest freq at or below target in a table in ascending order */
+static inline int cpufreq_table_find_index_ah(struct cpufreq_policy *policy,
+                                              unsigned int target_freq)
+{
+        struct cpufreq_frequency_table *table = policy->freq_table;
+        unsigned int freq;
+        int i, best = -1;
+
+        for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+                freq = table[i].frequency;
+
+                if (freq == target_freq)
+                        return i;
+
+                if (freq < target_freq) {
+                        best = i;
+                        continue;
+                }
+
+                /* No freq found below target_freq */
+                if (best == -1)
+                        return i;
+
+                return best;
+        }
+
+        return best;
+}
+
+/* Find highest freq at or below target in a table in descending order */
+static inline int cpufreq_table_find_index_dh(struct cpufreq_policy *policy,
+                                              unsigned int target_freq)
+{
+        struct cpufreq_frequency_table *table = policy->freq_table;
+        unsigned int freq;
+        int i, best = -1;
+
+        for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+                freq = table[i].frequency;
+
+                if (freq <= target_freq)
+                        return i;
+
+                best = i;
+        }
+
+        return best;
+}
+
+/* Works only on sorted freq-tables */
+static inline int cpufreq_table_find_index_h(struct cpufreq_policy *policy,
+                                             unsigned int target_freq)
+{
+        target_freq = clamp_val(target_freq, policy->min, policy->max);
+
+        if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
+                return cpufreq_table_find_index_ah(policy, target_freq);
+        else
+                return cpufreq_table_find_index_dh(policy, target_freq);
+}
+
+/* Find closest freq to target in a table in ascending order */
+static inline int cpufreq_table_find_index_ac(struct cpufreq_policy *policy,
+                                              unsigned int target_freq)
+{
+        struct cpufreq_frequency_table *table = policy->freq_table;
+        unsigned int freq;
+        int i, best = -1;
+
+        for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+                freq = table[i].frequency;
+
+                if (freq == target_freq)
+                        return i;
+
+                if (freq < target_freq) {
+                        best = i;
+                        continue;
+                }
+
+                /* No freq found below target_freq */
+                if (best == -1)
+                        return i;
+
+                /* Choose the closest freq */
+                if (target_freq - table[best].frequency > freq - target_freq)
+                        return i;
+
+                return best;
+        }
+
+        return best;
+}
+
+/* Find closest freq to target in a table in descending order */
+static inline int cpufreq_table_find_index_dc(struct cpufreq_policy *policy,
+                                              unsigned int target_freq)
+{
+        struct cpufreq_frequency_table *table = policy->freq_table;
+        unsigned int freq;
+        int i, best = -1;
+
+        for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+                freq = table[i].frequency;
+
+                if (freq == target_freq)
+                        return i;
+
+                if (freq > target_freq) {
+                        best = i;
+                        continue;
+                }
+
+                /* No freq found above target_freq */
+                if (best == -1)
+                        return i;
+
+                /* Choose the closest freq */
+                if (table[best].frequency - target_freq > target_freq - freq)
+                        return i;
+
+                return best;
+        }
+
+        return best;
+}
+
+/* Works only on sorted freq-tables */
+static inline int cpufreq_table_find_index_c(struct cpufreq_policy *policy,
+                                             unsigned int target_freq)
+{
+        target_freq = clamp_val(target_freq, policy->min, policy->max);
+
+        if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING)
+                return cpufreq_table_find_index_ac(policy, target_freq);
+        else
+                return cpufreq_table_find_index_dc(policy, target_freq);
+}
+
+static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
+                                                 unsigned int target_freq,
+                                                 unsigned int relation)
+{
+        if (unlikely(policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED))
+                return cpufreq_table_index_unsorted(policy, target_freq,
+                                                    relation);
+
+        switch (relation) {
+        case CPUFREQ_RELATION_L:
+                return cpufreq_table_find_index_l(policy, target_freq);
+        case CPUFREQ_RELATION_H:
+                return cpufreq_table_find_index_h(policy, target_freq);
+        case CPUFREQ_RELATION_C:
+                return cpufreq_table_find_index_c(policy, target_freq);
+        default:
+                pr_err("%s: Invalid relation: %d\n", __func__, relation);
+                return -EINVAL;
+        }
+}
 #else
 static inline int cpufreq_boost_trigger_state(int state)
 {