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Subject[PATCH 1/2] [CPUFREQ]: provide disable_cpufreq() function to disable the API.
Date
useful for disabling cpufreq altogether. The cpu frequency
scaling drivers and cpu frequency governors will fail to register.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
drivers/cpufreq/cpufreq.c | 24 ++++++++++++++++++++++++
include/linux/cpufreq.h | 2 ++
2 files changed, 26 insertions(+), 0 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 622013f..7f2f149 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -126,6 +126,15 @@ static int __init init_cpufreq_transition_notifier_list(void)
}
pure_initcall(init_cpufreq_transition_notifier_list);

+static int off __read_mostly;
+int cpufreq_disabled(void)
+{
+ return off;
+}
+void disable_cpufreq(void)
+{
+ off = 1;
+}
static LIST_HEAD(cpufreq_governor_list);
static DEFINE_MUTEX(cpufreq_governor_mutex);

@@ -1441,6 +1450,9 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
{
int retval = -EINVAL;

+ if (cpufreq_disabled())
+ return -ENODEV;
+
pr_debug("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
target_freq, relation);
if (cpu_online(policy->cpu) && cpufreq_driver->target)
@@ -1549,6 +1561,9 @@ int cpufreq_register_governor(struct cpufreq_governor *governor)
if (!governor)
return -EINVAL;

+ if (cpufreq_disabled())
+ return -ENODEV;
+
mutex_lock(&cpufreq_governor_mutex);

err = -EBUSY;
@@ -1572,6 +1587,9 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor)
if (!governor)
return;

+ if (cpufreq_disabled())
+ return;
+
#ifdef CONFIG_HOTPLUG_CPU
for_each_present_cpu(cpu) {
if (cpu_online(cpu))
@@ -1814,6 +1832,9 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
unsigned long flags;
int ret;

+ if (cpufreq_disabled())
+ return -ENODEV;
+
if (!driver_data || !driver_data->verify || !driver_data->init ||
((!driver_data->setpolicy) && (!driver_data->target)))
return -EINVAL;
@@ -1901,6 +1922,9 @@ static int __init cpufreq_core_init(void)
{
int cpu;

+ if (cpufreq_disabled())
+ return -ENODEV;
+
for_each_possible_cpu(cpu) {
per_cpu(cpufreq_policy_cpu, cpu) = -1;
init_rwsem(&per_cpu(cpu_policy_rwsem, cpu));
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 6216115..8ff4427 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -35,6 +35,7 @@
#ifdef CONFIG_CPU_FREQ
int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list);
int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list);
+extern void disable_cpufreq(void);
#else /* CONFIG_CPU_FREQ */
static inline int cpufreq_register_notifier(struct notifier_block *nb,
unsigned int list)
@@ -46,6 +47,7 @@ static inline int cpufreq_unregister_notifier(struct notifier_block *nb,
{
return 0;
}
+static inline void disable_cpufreq(void) { }
#endif /* CONFIG_CPU_FREQ */

/* if (cpufreq_driver->target) exists, the ->governor decides what frequency
--
1.7.9.48.g85da4d


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