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Commit 448c8b1d authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk
Browse files

provide disable_cpufreq() function to disable the API. 



useful for disabling cpufreq altogether. The cpu frequency
scaling drivers and cpu frequency governors will fail to register.

Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarDave Jones <davej@redhat.com>
parent 4bc25af7

drivers/cpufreq/cpufreq.c

+24 −0
Original line number Diff line number Diff line
@@ -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);
@@ -1442,6 +1451,9 @@ 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)
@@ -1550,6 +1562,9 @@ int cpufreq_register_governor(struct cpufreq_governor *governor) 
	if (!governor)

		return -EINVAL;



	if (cpufreq_disabled())

		return -ENODEV;



	mutex_lock(&cpufreq_governor_mutex);



	err = -EBUSY;
@@ -1573,6 +1588,9 @@ 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))
@@ -1815,6 +1833,9 @@ 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;
@@ -1902,6 +1923,9 @@ 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));

include/linux/cpufreq.h

+2 −0
Original line number Diff line number Diff line
@@ -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