cpufreq: arm_big_little: add in-kernel switching (IKS) support
authorViresh Kumar <viresh.kumar@linaro.org>
Wed, 30 Oct 2013 19:44:40 +0000 (15:44 -0400)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Wed, 30 Oct 2013 23:10:53 +0000 (00:10 +0100)
This patch adds IKS (In Kernel Switcher) support to cpufreq driver.

This creates a combined freq table for A7-A15 CPU pairs. A7 frequencies
are virtualized and scaled down to half the actual frequencies to
approximate a linear scale across the combined A7+A15 range. When the
requested frequency change crosses the A7-A15 boundary a cluster switch
is invoked.

Based on earlier work from Sudeep KarkadaNagesha.

Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
drivers/cpufreq/arm_big_little.c
drivers/cpufreq/arm_big_little.h

index 163e3378fe176f9c3894ec79b056dfef3f070239..9986f79123289ba8ae2f60abd42c680d44abc93c 100644 (file)
 #include <linux/cpufreq.h>
 #include <linux/cpumask.h>
 #include <linux/export.h>
+#include <linux/mutex.h>
 #include <linux/of_platform.h>
 #include <linux/pm_opp.h>
 #include <linux/slab.h>
 #include <linux/topology.h>
 #include <linux/types.h>
+#include <asm/bL_switcher.h>
 
 #include "arm_big_little.h"
 
 /* Currently we support only two clusters */
+#define A15_CLUSTER    0
+#define A7_CLUSTER     1
 #define MAX_CLUSTERS   2
 
+#ifdef CONFIG_BL_SWITCHER
+#define is_bL_switching_enabled()      true
+#else
+#define is_bL_switching_enabled()      false
+#endif
+
+#define ACTUAL_FREQ(cluster, freq)  ((cluster == A7_CLUSTER) ? freq << 1 : freq)
+#define VIRT_FREQ(cluster, freq)    ((cluster == A7_CLUSTER) ? freq >> 1 : freq)
+
 static struct cpufreq_arm_bL_ops *arm_bL_ops;
 static struct clk *clk[MAX_CLUSTERS];
-static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS];
-static atomic_t cluster_usage[MAX_CLUSTERS] = {ATOMIC_INIT(0), ATOMIC_INIT(0)};
+static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
+static atomic_t cluster_usage[MAX_CLUSTERS + 1];
+
+static unsigned int clk_big_min;       /* (Big) clock frequencies */
+static unsigned int clk_little_max;    /* Maximum clock frequency (Little) */
+
+static DEFINE_PER_CPU(unsigned int, physical_cluster);
+static DEFINE_PER_CPU(unsigned int, cpu_last_req_freq);
+
+static struct mutex cluster_lock[MAX_CLUSTERS];
+
+static inline int raw_cpu_to_cluster(int cpu)
+{
+       return topology_physical_package_id(cpu);
+}
+
+static inline int cpu_to_cluster(int cpu)
+{
+       return is_bL_switching_enabled() ?
+               MAX_CLUSTERS : raw_cpu_to_cluster(cpu);
+}
+
+static unsigned int find_cluster_maxfreq(int cluster)
+{
+       int j;
+       u32 max_freq = 0, cpu_freq;
+
+       for_each_online_cpu(j) {
+               cpu_freq = per_cpu(cpu_last_req_freq, j);
+
+               if ((cluster == per_cpu(physical_cluster, j)) &&
+                               (max_freq < cpu_freq))
+                       max_freq = cpu_freq;
+       }
+
+       pr_debug("%s: cluster: %d, max freq: %d\n", __func__, cluster,
+                       max_freq);
+
+       return max_freq;
+}
+
+static unsigned int clk_get_cpu_rate(unsigned int cpu)
+{
+       u32 cur_cluster = per_cpu(physical_cluster, cpu);
+       u32 rate = clk_get_rate(clk[cur_cluster]) / 1000;
+
+       /* For switcher we use virtual A7 clock rates */
+       if (is_bL_switching_enabled())
+               rate = VIRT_FREQ(cur_cluster, rate);
+
+       pr_debug("%s: cpu: %d, cluster: %d, freq: %u\n", __func__, cpu,
+                       cur_cluster, rate);
+
+       return rate;
+}
+
+static unsigned int bL_cpufreq_get_rate(unsigned int cpu)
+{
+       if (is_bL_switching_enabled()) {
+               pr_debug("%s: freq: %d\n", __func__, per_cpu(cpu_last_req_freq,
+                                       cpu));
+
+               return per_cpu(cpu_last_req_freq, cpu);
+       } else {
+               return clk_get_cpu_rate(cpu);
+       }
+}
 
-static unsigned int bL_cpufreq_get(unsigned int cpu)
+static unsigned int
+bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate)
 {
-       u32 cur_cluster = cpu_to_cluster(cpu);
+       u32 new_rate, prev_rate;
+       int ret;
+       bool bLs = is_bL_switching_enabled();
+
+       mutex_lock(&cluster_lock[new_cluster]);
+
+       if (bLs) {
+               prev_rate = per_cpu(cpu_last_req_freq, cpu);
+               per_cpu(cpu_last_req_freq, cpu) = rate;
+               per_cpu(physical_cluster, cpu) = new_cluster;
+
+               new_rate = find_cluster_maxfreq(new_cluster);
+               new_rate = ACTUAL_FREQ(new_cluster, new_rate);
+       } else {
+               new_rate = rate;
+       }
+
+       pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d, freq: %d\n",
+                       __func__, cpu, old_cluster, new_cluster, new_rate);
+
+       ret = clk_set_rate(clk[new_cluster], new_rate * 1000);
+       if (WARN_ON(ret)) {
+               pr_err("clk_set_rate failed: %d, new cluster: %d\n", ret,
+                               new_cluster);
+               if (bLs) {
+                       per_cpu(cpu_last_req_freq, cpu) = prev_rate;
+                       per_cpu(physical_cluster, cpu) = old_cluster;
+               }
+
+               mutex_unlock(&cluster_lock[new_cluster]);
+
+               return ret;
+       }
+
+       mutex_unlock(&cluster_lock[new_cluster]);
+
+       /* Recalc freq for old cluster when switching clusters */
+       if (old_cluster != new_cluster) {
+               pr_debug("%s: cpu: %d, old cluster: %d, new cluster: %d\n",
+                               __func__, cpu, old_cluster, new_cluster);
+
+               /* Switch cluster */
+               bL_switch_request(cpu, new_cluster);
+
+               mutex_lock(&cluster_lock[old_cluster]);
 
-       return clk_get_rate(clk[cur_cluster]) / 1000;
+               /* Set freq of old cluster if there are cpus left on it */
+               new_rate = find_cluster_maxfreq(old_cluster);
+               new_rate = ACTUAL_FREQ(old_cluster, new_rate);
+
+               if (new_rate) {
+                       pr_debug("%s: Updating rate of old cluster: %d, to freq: %d\n",
+                                       __func__, old_cluster, new_rate);
+
+                       if (clk_set_rate(clk[old_cluster], new_rate * 1000))
+                               pr_err("%s: clk_set_rate failed: %d, old cluster: %d\n",
+                                               __func__, ret, old_cluster);
+               }
+               mutex_unlock(&cluster_lock[old_cluster]);
+       }
+
+       return 0;
 }
 
 /* Set clock frequency */
@@ -52,63 +190,164 @@ static int bL_cpufreq_set_target(struct cpufreq_policy *policy,
                unsigned int index)
 {
        struct cpufreq_freqs freqs;
-       u32 cpu = policy->cpu, cur_cluster;
+       u32 cpu = policy->cpu, cur_cluster, new_cluster, actual_cluster;
        int ret = 0;
 
-       cur_cluster = cpu_to_cluster(policy->cpu);
+       cur_cluster = cpu_to_cluster(cpu);
+       new_cluster = actual_cluster = per_cpu(physical_cluster, cpu);
 
-       freqs.old = bL_cpufreq_get(policy->cpu);
+       freqs.old = bL_cpufreq_get_rate(cpu);
        freqs.new = freq_table[cur_cluster][index].frequency;
 
        pr_debug("%s: cpu: %d, cluster: %d, oldfreq: %d, target freq: %d, new freq: %d\n",
                        __func__, cpu, cur_cluster, freqs.old, freqs.new,
                        freqs.new);
 
+       if (is_bL_switching_enabled()) {
+               if ((actual_cluster == A15_CLUSTER) &&
+                               (freqs.new < clk_big_min)) {
+                       new_cluster = A7_CLUSTER;
+               } else if ((actual_cluster == A7_CLUSTER) &&
+                               (freqs.new > clk_little_max)) {
+                       new_cluster = A15_CLUSTER;
+               }
+       }
+
        cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
 
-       ret = clk_set_rate(clk[cur_cluster], freqs.new * 1000);
-       if (ret) {
-               pr_err("clk_set_rate failed: %d\n", ret);
+       ret = bL_cpufreq_set_rate(cpu, actual_cluster, new_cluster, freqs.new);
+       if (ret)
                freqs.new = freqs.old;
-       }
 
        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 
        return ret;
 }
 
+static inline u32 get_table_count(struct cpufreq_frequency_table *table)
+{
+       int count;
+
+       for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
+               ;
+
+       return count;
+}
+
+/* get the minimum frequency in the cpufreq_frequency_table */
+static inline u32 get_table_min(struct cpufreq_frequency_table *table)
+{
+       int i;
+       uint32_t min_freq = ~0;
+       for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++)
+               if (table[i].frequency < min_freq)
+                       min_freq = table[i].frequency;
+       return min_freq;
+}
+
+/* get the maximum frequency in the cpufreq_frequency_table */
+static inline u32 get_table_max(struct cpufreq_frequency_table *table)
+{
+       int i;
+       uint32_t max_freq = 0;
+       for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++)
+               if (table[i].frequency > max_freq)
+                       max_freq = table[i].frequency;
+       return max_freq;
+}
+
+static int merge_cluster_tables(void)
+{
+       int i, j, k = 0, count = 1;
+       struct cpufreq_frequency_table *table;
+
+       for (i = 0; i < MAX_CLUSTERS; i++)
+               count += get_table_count(freq_table[i]);
+
+       table = kzalloc(sizeof(*table) * count, GFP_KERNEL);
+       if (!table)
+               return -ENOMEM;
+
+       freq_table[MAX_CLUSTERS] = table;
+
+       /* Add in reverse order to get freqs in increasing order */
+       for (i = MAX_CLUSTERS - 1; i >= 0; i--) {
+               for (j = 0; freq_table[i][j].frequency != CPUFREQ_TABLE_END;
+                               j++) {
+                       table[k].frequency = VIRT_FREQ(i,
+                                       freq_table[i][j].frequency);
+                       pr_debug("%s: index: %d, freq: %d\n", __func__, k,
+                                       table[k].frequency);
+                       k++;
+               }
+       }
+
+       table[k].driver_data = k;
+       table[k].frequency = CPUFREQ_TABLE_END;
+
+       pr_debug("%s: End, table: %p, count: %d\n", __func__, table, k);
+
+       return 0;
+}
+
+static void _put_cluster_clk_and_freq_table(struct device *cpu_dev)
+{
+       u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
+
+       if (!freq_table[cluster])
+               return;
+
+       clk_put(clk[cluster]);
+       dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
+       dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);
+}
+
 static void put_cluster_clk_and_freq_table(struct device *cpu_dev)
 {
        u32 cluster = cpu_to_cluster(cpu_dev->id);
+       int i;
+
+       if (atomic_dec_return(&cluster_usage[cluster]))
+               return;
+
+       if (cluster < MAX_CLUSTERS)
+               return _put_cluster_clk_and_freq_table(cpu_dev);
 
-       if (!atomic_dec_return(&cluster_usage[cluster])) {
-               clk_put(clk[cluster]);
-               dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
-               dev_dbg(cpu_dev, "%s: cluster: %d\n", __func__, cluster);
+       for_each_present_cpu(i) {
+               struct device *cdev = get_cpu_device(i);
+               if (!cdev) {
+                       pr_err("%s: failed to get cpu%d device\n", __func__, i);
+                       return;
+               }
+
+               _put_cluster_clk_and_freq_table(cdev);
        }
+
+       /* free virtual table */
+       kfree(freq_table[cluster]);
 }
 
-static int get_cluster_clk_and_freq_table(struct device *cpu_dev)
+static int _get_cluster_clk_and_freq_table(struct device *cpu_dev)
 {
-       u32 cluster = cpu_to_cluster(cpu_dev->id);
+       u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
        char name[14] = "cpu-cluster.";
        int ret;
 
-       if (atomic_inc_return(&cluster_usage[cluster]) != 1)
+       if (freq_table[cluster])
                return 0;
 
        ret = arm_bL_ops->init_opp_table(cpu_dev);
        if (ret) {
                dev_err(cpu_dev, "%s: init_opp_table failed, cpu: %d, err: %d\n",
                                __func__, cpu_dev->id, ret);
-               goto atomic_dec;
+               goto out;
        }
 
        ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
        if (ret) {
                dev_err(cpu_dev, "%s: failed to init cpufreq table, cpu: %d, err: %d\n",
                                __func__, cpu_dev->id, ret);
-               goto atomic_dec;
+               goto out;
        }
 
        name[12] = cluster + '0';
@@ -125,13 +364,72 @@ static int get_cluster_clk_and_freq_table(struct device *cpu_dev)
        ret = PTR_ERR(clk[cluster]);
        dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
 
-atomic_dec:
-       atomic_dec(&cluster_usage[cluster]);
+out:
        dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
                        cluster);
        return ret;
 }
 
+static int get_cluster_clk_and_freq_table(struct device *cpu_dev)
+{
+       u32 cluster = cpu_to_cluster(cpu_dev->id);
+       int i, ret;
+
+       if (atomic_inc_return(&cluster_usage[cluster]) != 1)
+               return 0;
+
+       if (cluster < MAX_CLUSTERS) {
+               ret = _get_cluster_clk_and_freq_table(cpu_dev);
+               if (ret)
+                       atomic_dec(&cluster_usage[cluster]);
+               return ret;
+       }
+
+       /*
+        * Get data for all clusters and fill virtual cluster with a merge of
+        * both
+        */
+       for_each_present_cpu(i) {
+               struct device *cdev = get_cpu_device(i);
+               if (!cdev) {
+                       pr_err("%s: failed to get cpu%d device\n", __func__, i);
+                       return -ENODEV;
+               }
+
+               ret = _get_cluster_clk_and_freq_table(cdev);
+               if (ret)
+                       goto put_clusters;
+       }
+
+       ret = merge_cluster_tables();
+       if (ret)
+               goto put_clusters;
+
+       /* Assuming 2 cluster, set clk_big_min and clk_little_max */
+       clk_big_min = get_table_min(freq_table[0]);
+       clk_little_max = VIRT_FREQ(1, get_table_max(freq_table[1]));
+
+       pr_debug("%s: cluster: %d, clk_big_min: %d, clk_little_max: %d\n",
+                       __func__, cluster, clk_big_min, clk_little_max);
+
+       return 0;
+
+put_clusters:
+       for_each_present_cpu(i) {
+               struct device *cdev = get_cpu_device(i);
+               if (!cdev) {
+                       pr_err("%s: failed to get cpu%d device\n", __func__, i);
+                       return -ENODEV;
+               }
+
+               _put_cluster_clk_and_freq_table(cdev);
+       }
+
+       atomic_dec(&cluster_usage[cluster]);
+
+       return ret;
+}
+
 /* Per-CPU initialization */
 static int bL_cpufreq_init(struct cpufreq_policy *policy)
 {
@@ -158,13 +456,23 @@ static int bL_cpufreq_init(struct cpufreq_policy *policy)
                return ret;
        }
 
+       if (cur_cluster < MAX_CLUSTERS) {
+               cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
+
+               per_cpu(physical_cluster, policy->cpu) = cur_cluster;
+       } else {
+               /* Assumption: during init, we are always running on A15 */
+               per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER;
+       }
+
        if (arm_bL_ops->get_transition_latency)
                policy->cpuinfo.transition_latency =
                        arm_bL_ops->get_transition_latency(cpu_dev);
        else
                policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 
-       cpumask_copy(policy->cpus, topology_core_cpumask(policy->cpu));
+       if (is_bL_switching_enabled())
+               per_cpu(cpu_last_req_freq, policy->cpu) = clk_get_cpu_rate(policy->cpu);
 
        dev_info(cpu_dev, "%s: CPU %d initialized\n", __func__, policy->cpu);
        return 0;
@@ -194,7 +502,7 @@ static struct cpufreq_driver bL_cpufreq_driver = {
                                        CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
        .verify                 = cpufreq_generic_frequency_table_verify,
        .target_index           = bL_cpufreq_set_target,
-       .get                    = bL_cpufreq_get,
+       .get                    = bL_cpufreq_get_rate,
        .init                   = bL_cpufreq_init,
        .exit                   = bL_cpufreq_exit,
        .attr                   = cpufreq_generic_attr,
@@ -202,7 +510,7 @@ static struct cpufreq_driver bL_cpufreq_driver = {
 
 int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)
 {
-       int ret;
+       int ret, i;
 
        if (arm_bL_ops) {
                pr_debug("%s: Already registered: %s, exiting\n", __func__,
@@ -217,6 +525,9 @@ int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops)
 
        arm_bL_ops = ops;
 
+       for (i = 0; i < MAX_CLUSTERS; i++)
+               mutex_init(&cluster_lock[i]);
+
        ret = cpufreq_register_driver(&bL_cpufreq_driver);
        if (ret) {
                pr_info("%s: Failed registering platform driver: %s, err: %d\n",
index 79b2ce17884dd9cc645cb5a34c33e90290bba10a..70f18fc12d4ad2a1a2c14f00ae1844e5378cdaee 100644 (file)
@@ -34,11 +34,6 @@ struct cpufreq_arm_bL_ops {
        int (*init_opp_table)(struct device *cpu_dev);
 };
 
-static inline int cpu_to_cluster(int cpu)
-{
-       return topology_physical_package_id(cpu);
-}
-
 int bL_cpufreq_register(struct cpufreq_arm_bL_ops *ops);
 void bL_cpufreq_unregister(struct cpufreq_arm_bL_ops *ops);