[PATCH v2 1/2] cpufreq: arm_big_little: add in-kernel switching (IKS) support
Nicolas Pitre
nicolas.pitre at linaro.org
Wed Oct 30 15:44:40 EDT 2013
From: Viresh Kumar <viresh.kumar at linaro.org>
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.
Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha at arm.com>
Signed-off-by: Viresh Kumar <viresh.kumar at linaro.org>
Signed-off-by: Nicolas Pitre <nico at linaro.org>
---
drivers/cpufreq/arm_big_little.c | 363 ++++++++++++++++++++++++++++++++++++---
drivers/cpufreq/arm_big_little.h | 5 -
2 files changed, 337 insertions(+), 31 deletions(-)
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index 163e3378fe..a6a8f74811 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -24,27 +24,165 @@
#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;
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",
diff --git a/drivers/cpufreq/arm_big_little.h b/drivers/cpufreq/arm_big_little.h
index 79b2ce1788..70f18fc12d 100644
--- a/drivers/cpufreq/arm_big_little.h
+++ b/drivers/cpufreq/arm_big_little.h
@@ -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);
--
1.8.4.108.g55ea5f6
More information about the linux-arm-kernel
mailing list