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Subject[PATCH 2/3] cpufreq: Implement freq-constraint callback
Date
This implements the frequency constraint callback and registers it with
the freq-constraint framework whenever a policy is created. On policy
removal the callback is unregistered.

The constraints are also taken into consideration in
cpufreq_set_policy().

No constraints are added until now though.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
drivers/cpufreq/Kconfig | 1 +
drivers/cpufreq/cpufreq.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 45 insertions(+)

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 608af20a3494..2c2842cf2734 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -2,6 +2,7 @@ menu "CPU Frequency scaling"

config CPU_FREQ
bool "CPU Frequency scaling"
+ select DEVICE_FREQ_CONSTRAINT
select SRCU
help
CPU Frequency scaling allows you to change the clock speed of
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a8fa684f5f90..63028612d011 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -21,6 +21,7 @@
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/device.h>
+#include <linux/freq_constraint.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/module.h>
@@ -1163,6 +1164,7 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
per_cpu(cpufreq_cpu_data, cpu) = NULL;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);

+ freq_constraint_remove_cpumask_callback(policy->related_cpus);
cpufreq_policy_put_kobj(policy);
free_cpumask_var(policy->real_cpus);
free_cpumask_var(policy->related_cpus);
@@ -1170,6 +1172,24 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
kfree(policy);
}

+static void freq_constraint_callback(void *param)
+{
+ struct cpufreq_policy *policy = param;
+ struct cpufreq_policy new_policy = *policy;
+
+ new_policy.min = policy->user_policy.min;
+ new_policy.max = policy->user_policy.max;
+
+ down_write(&policy->rwsem);
+ if (policy_is_inactive(policy))
+ goto unlock;
+
+ cpufreq_set_policy(policy, &new_policy);
+
+unlock:
+ up_write(&policy->rwsem);
+}
+
static int cpufreq_online(unsigned int cpu)
{
struct cpufreq_policy *policy;
@@ -1236,6 +1256,14 @@ static int cpufreq_online(unsigned int cpu)
per_cpu(cpufreq_cpu_data, j) = policy;
add_cpu_dev_symlink(policy, j);
}
+
+ ret = freq_constraint_set_cpumask_callback(policy->related_cpus,
+ freq_constraint_callback, policy);
+ if (ret) {
+ pr_err("Failed to set freq-constraints: %d (%*pbl)\n",
+ ret, cpumask_pr_args(policy->cpus));
+ goto out_destroy_policy;
+ }
} else {
policy->min = policy->user_policy.min;
policy->max = policy->user_policy.max;
@@ -2198,6 +2226,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
struct cpufreq_policy *new_policy)
{
struct cpufreq_governor *old_gov;
+ struct device *cpu_dev = get_cpu_device(policy->cpu);
+ unsigned long fc_min, fc_max;
int ret;

pr_debug("setting new policy for CPU %u: %u - %u kHz\n",
@@ -2217,6 +2247,20 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
if (ret)
return ret;

+ ret = freq_constraints_get(cpu_dev, &fc_min, &fc_max);
+ if (ret) {
+ dev_err(cpu_dev, "cpufreq: Failed to get freq-constraints\n");
+ } else {
+ if (fc_min > new_policy->min)
+ new_policy->min = fc_min;
+ if (fc_max < new_policy->max)
+ new_policy->max = fc_max;
+ }
+
+ /*
+ * The notifier-chain shall be removed once all the users of
+ * CPUFREQ_ADJUST are moved to use the freq-constraints.
+ */
/* adjust if necessary - all reasons */
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_ADJUST, new_policy);
--
2.7.4
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