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android_kernel_xiaomi_sm8350/drivers/cpufreq/cpufreq.c
Jeremy Fitzhardinge ea71497020 [CPUFREQ] [2/2] demand load governor modules. 
Demand-load cpufreq governor modules if needed.

Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Dave Jones <davej@redhat.com>
2006-07-31 18:37:06 -04:00

1674 lines
42 KiB
C
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/*
* linux/drivers/cpufreq/cpufreq.c
*
* Copyright (C) 2001 Russell King
* (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
*
* Oct 2005 - Ashok Raj <ashok.raj@intel.com>
* Added handling for CPU hotplug
* Feb 2006 - Jacob Shin <jacob.shin@amd.com>
* Fix handling for CPU hotplug -- affected CPUs
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/notifier.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/completion.h>
#include <linux/mutex.h>
#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_CORE, "cpufreq-core", msg)
/**
* The "cpufreq driver" - the arch- or hardware-dependend low
* level driver of CPUFreq support, and its spinlock. This lock
* also protects the cpufreq_cpu_data array.
*/
static struct cpufreq_driver *cpufreq_driver;
static struct cpufreq_policy *cpufreq_cpu_data[NR_CPUS];
static DEFINE_SPINLOCK(cpufreq_driver_lock);
/* internal prototypes */
static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event);
static void handle_update(void *data);
/**
* Two notifier lists: the "policy" list is involved in the
* validation process for a new CPU frequency policy; the
* "transition" list for kernel code that needs to handle
* changes to devices when the CPU clock speed changes.
* The mutex locks both lists.
*/
static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
static BLOCKING_NOTIFIER_HEAD(cpufreq_transition_notifier_list);
static LIST_HEAD(cpufreq_governor_list);
static DEFINE_MUTEX (cpufreq_governor_mutex);
struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
{
struct cpufreq_policy *data;
unsigned long flags;
if (cpu >= NR_CPUS)
goto err_out;
/* get the cpufreq driver */
spin_lock_irqsave(&cpufreq_driver_lock, flags);
if (!cpufreq_driver)
goto err_out_unlock;
if (!try_module_get(cpufreq_driver->owner))
goto err_out_unlock;
/* get the CPU */
data = cpufreq_cpu_data[cpu];
if (!data)
goto err_out_put_module;
if (!kobject_get(&data->kobj))
goto err_out_put_module;
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
return data;
err_out_put_module:
module_put(cpufreq_driver->owner);
err_out_unlock:
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
err_out:
return NULL;
}
EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
void cpufreq_cpu_put(struct cpufreq_policy *data)
{
kobject_put(&data->kobj);
module_put(cpufreq_driver->owner);
}
EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
/*********************************************************************
* UNIFIED DEBUG HELPERS *
*********************************************************************/
#ifdef CONFIG_CPU_FREQ_DEBUG
/* what part(s) of the CPUfreq subsystem are debugged? */
static unsigned int debug;
/* is the debug output ratelimit'ed using printk_ratelimit? User can
* set or modify this value.
*/
static unsigned int debug_ratelimit = 1;
/* is the printk_ratelimit'ing enabled? It's enabled after a successful
* loading of a cpufreq driver, temporarily disabled when a new policy
* is set, and disabled upon cpufreq driver removal
*/
static unsigned int disable_ratelimit = 1;
static DEFINE_SPINLOCK(disable_ratelimit_lock);
static void cpufreq_debug_enable_ratelimit(void)
{
unsigned long flags;
spin_lock_irqsave(&disable_ratelimit_lock, flags);
if (disable_ratelimit)
disable_ratelimit--;
spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
}
static void cpufreq_debug_disable_ratelimit(void)
{
unsigned long flags;
spin_lock_irqsave(&disable_ratelimit_lock, flags);
disable_ratelimit++;
spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
}
void cpufreq_debug_printk(unsigned int type, const char *prefix, const char *fmt, ...)
{
char s[256];
va_list args;
unsigned int len;
unsigned long flags;
WARN_ON(!prefix);
if (type & debug) {
spin_lock_irqsave(&disable_ratelimit_lock, flags);
if (!disable_ratelimit && debug_ratelimit && !printk_ratelimit()) {
spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
return;
}
spin_unlock_irqrestore(&disable_ratelimit_lock, flags);
len = snprintf(s, 256, KERN_DEBUG "%s: ", prefix);
va_start(args, fmt);
len += vsnprintf(&s[len], (256 - len), fmt, args);
va_end(args);
printk(s);
WARN_ON(len < 5);
}
}
EXPORT_SYMBOL(cpufreq_debug_printk);
module_param(debug, uint, 0644);
MODULE_PARM_DESC(debug, "CPUfreq debugging: add 1 to debug core, 2 to debug drivers, and 4 to debug governors.");
module_param(debug_ratelimit, uint, 0644);
MODULE_PARM_DESC(debug_ratelimit, "CPUfreq debugging: set to 0 to disable ratelimiting.");
#else /* !CONFIG_CPU_FREQ_DEBUG */
static inline void cpufreq_debug_enable_ratelimit(void) { return; }
static inline void cpufreq_debug_disable_ratelimit(void) { return; }
#endif /* CONFIG_CPU_FREQ_DEBUG */
/*********************************************************************
* EXTERNALLY AFFECTING FREQUENCY CHANGES *
*********************************************************************/
/**
* adjust_jiffies - adjust the system "loops_per_jiffy"
*
* This function alters the system "loops_per_jiffy" for the clock
* speed change. Note that loops_per_jiffy cannot be updated on SMP
* systems as each CPU might be scaled differently. So, use the arch
* per-CPU loops_per_jiffy value wherever possible.
*/
#ifndef CONFIG_SMP
static unsigned long l_p_j_ref;
static unsigned int l_p_j_ref_freq;
static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
{
if (ci->flags & CPUFREQ_CONST_LOOPS)
return;
if (!l_p_j_ref_freq) {
l_p_j_ref = loops_per_jiffy;
l_p_j_ref_freq = ci->old;
dprintk("saving %lu as reference value for loops_per_jiffy; freq is %u kHz\n", l_p_j_ref, l_p_j_ref_freq);
}
if ((val == CPUFREQ_PRECHANGE && ci->old < ci->new) ||
(val == CPUFREQ_POSTCHANGE && ci->old > ci->new) ||
(val == CPUFREQ_RESUMECHANGE || val == CPUFREQ_SUSPENDCHANGE)) {
loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq, ci->new);
dprintk("scaling loops_per_jiffy to %lu for frequency %u kHz\n", loops_per_jiffy, ci->new);
}
}
#else
static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci) { return; }
#endif
/**
* cpufreq_notify_transition - call notifier chain and adjust_jiffies
* on frequency transition.
*
* This function calls the transition notifiers and the "adjust_jiffies"
* function. It is called twice on all CPU frequency changes that have
* external effects.
*/
void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
{
struct cpufreq_policy *policy;
BUG_ON(irqs_disabled());
freqs->flags = cpufreq_driver->flags;
dprintk("notification %u of frequency transition to %u kHz\n",
state, freqs->new);
policy = cpufreq_cpu_data[freqs->cpu];
switch (state) {
case CPUFREQ_PRECHANGE:
/* detect if the driver reported a value as "old frequency"
* which is not equal to what the cpufreq core thinks is
* "old frequency".
*/
if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
if ((policy) && (policy->cpu == freqs->cpu) &&
(policy->cur) && (policy->cur != freqs->old)) {
dprintk("Warning: CPU frequency is"
" %u, cpufreq assumed %u kHz.\n",
freqs->old, policy->cur);
freqs->old = policy->cur;
}
}
blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
CPUFREQ_PRECHANGE, freqs);
adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
break;
case CPUFREQ_POSTCHANGE:
adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
CPUFREQ_POSTCHANGE, freqs);
if (likely(policy) && likely(policy->cpu == freqs->cpu))
policy->cur = freqs->new;
break;
}
}
EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
/*********************************************************************
* SYSFS INTERFACE *
*********************************************************************/
static struct cpufreq_governor *__find_governor(const char *str_governor)
{
struct cpufreq_governor *t;
list_for_each_entry(t, &cpufreq_governor_list, governor_list)
if (!strnicmp(str_governor,t->name,CPUFREQ_NAME_LEN))
return t;
return NULL;
}
/**
* cpufreq_parse_governor - parse a governor string
*/
static int cpufreq_parse_governor (char *str_governor, unsigned int *policy,
struct cpufreq_governor **governor)
{
int err = -EINVAL;
if (!cpufreq_driver)
goto out;
if (cpufreq_driver->setpolicy) {
if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
*policy = CPUFREQ_POLICY_PERFORMANCE;
err = 0;
} else if (!strnicmp(str_governor, "powersave", CPUFREQ_NAME_LEN)) {
*policy = CPUFREQ_POLICY_POWERSAVE;
err = 0;
}
} else if (cpufreq_driver->target) {
struct cpufreq_governor *t;
mutex_lock(&cpufreq_governor_mutex);
t = __find_governor(str_governor);
if (t == NULL) {
char *name = kasprintf(GFP_KERNEL, "cpufreq_%s", str_governor);
if (name) {
int ret;
mutex_unlock(&cpufreq_governor_mutex);
ret = request_module(name);
mutex_lock(&cpufreq_governor_mutex);
if (ret == 0)
t = __find_governor(str_governor);
}
kfree(name);
}
if (t != NULL) {
*governor = t;
err = 0;
}
mutex_unlock(&cpufreq_governor_mutex);
}
out:
return err;
}
/* drivers/base/cpu.c */
extern struct sysdev_class cpu_sysdev_class;
/**
* cpufreq_per_cpu_attr_read() / show_##file_name() - print out cpufreq information
*
* Write out information from cpufreq_driver->policy[cpu]; object must be
* "unsigned int".
*/
#define show_one(file_name, object) \
static ssize_t show_##file_name \
(struct cpufreq_policy * policy, char *buf) \
{ \
return sprintf (buf, "%u\n", policy->object); \
}
show_one(cpuinfo_min_freq, cpuinfo.min_freq);
show_one(cpuinfo_max_freq, cpuinfo.max_freq);
show_one(scaling_min_freq, min);
show_one(scaling_max_freq, max);
show_one(scaling_cur_freq, cur);
static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_policy *policy);
/**
* cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
*/
#define store_one(file_name, object) \
static ssize_t store_##file_name \
(struct cpufreq_policy * policy, const char *buf, size_t count) \
{ \
unsigned int ret = -EINVAL; \
struct cpufreq_policy new_policy; \
\
ret = cpufreq_get_policy(&new_policy, policy->cpu); \
if (ret) \
return -EINVAL; \
\
ret = sscanf (buf, "%u", &new_policy.object); \
if (ret != 1) \
return -EINVAL; \
\
lock_cpu_hotplug(); \
mutex_lock(&policy->lock); \
ret = __cpufreq_set_policy(policy, &new_policy); \
policy->user_policy.object = policy->object; \
mutex_unlock(&policy->lock); \
unlock_cpu_hotplug(); \
\
return ret ? ret : count; \
}
store_one(scaling_min_freq,min);
store_one(scaling_max_freq,max);
/**
* show_cpuinfo_cur_freq - current CPU frequency as detected by hardware
*/
static ssize_t show_cpuinfo_cur_freq (struct cpufreq_policy * policy, char *buf)
{
unsigned int cur_freq = cpufreq_get(policy->cpu);
if (!cur_freq)
return sprintf(buf, "<unknown>");
return sprintf(buf, "%u\n", cur_freq);
}
/**
* show_scaling_governor - show the current policy for the specified CPU
*/
static ssize_t show_scaling_governor (struct cpufreq_policy * policy, char *buf)
{
if(policy->policy == CPUFREQ_POLICY_POWERSAVE)
return sprintf(buf, "powersave\n");
else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
return sprintf(buf, "performance\n");
else if (policy->governor)
return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n", policy->governor->name);
return -EINVAL;
}
/**
* store_scaling_governor - store policy for the specified CPU
*/
static ssize_t store_scaling_governor (struct cpufreq_policy * policy,
const char *buf, size_t count)
{
unsigned int ret = -EINVAL;
char str_governor[16];
struct cpufreq_policy new_policy;
ret = cpufreq_get_policy(&new_policy, policy->cpu);
if (ret)
return ret;
ret = sscanf (buf, "%15s", str_governor);
if (ret != 1)
return -EINVAL;
if (cpufreq_parse_governor(str_governor, &new_policy.policy, &new_policy.governor))
return -EINVAL;
lock_cpu_hotplug();
/* Do not use cpufreq_set_policy here or the user_policy.max
will be wrongly overridden */
mutex_lock(&policy->lock);
ret = __cpufreq_set_policy(policy, &new_policy);
policy->user_policy.policy = policy->policy;
policy->user_policy.governor = policy->governor;
mutex_unlock(&policy->lock);
unlock_cpu_hotplug();
return ret ? ret : count;
}
/**
* show_scaling_driver - show the cpufreq driver currently loaded
*/
static ssize_t show_scaling_driver (struct cpufreq_policy * policy, char *buf)
{
return scnprintf(buf, CPUFREQ_NAME_LEN, "%s\n", cpufreq_driver->name);
}
/**
* show_scaling_available_governors - show the available CPUfreq governors
*/
static ssize_t show_scaling_available_governors (struct cpufreq_policy * policy,
char *buf)
{
ssize_t i = 0;
struct cpufreq_governor *t;
if (!cpufreq_driver->target) {
i += sprintf(buf, "performance powersave");
goto out;
}
list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char)) - (CPUFREQ_NAME_LEN + 2)))
goto out;
i += scnprintf(&buf[i], CPUFREQ_NAME_LEN, "%s ", t->name);
}
out:
i += sprintf(&buf[i], "\n");
return i;
}
/**
* show_affected_cpus - show the CPUs affected by each transition
*/
static ssize_t show_affected_cpus (struct cpufreq_policy * policy, char *buf)
{
ssize_t i = 0;
unsigned int cpu;
for_each_cpu_mask(cpu, policy->cpus) {
if (i)
i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), " ");
i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u", cpu);
if (i >= (PAGE_SIZE - 5))
break;
}
i += sprintf(&buf[i], "\n");
return i;
}
#define define_one_ro(_name) \
static struct freq_attr _name = \
__ATTR(_name, 0444, show_##_name, NULL)
#define define_one_ro0400(_name) \
static struct freq_attr _name = \
__ATTR(_name, 0400, show_##_name, NULL)
#define define_one_rw(_name) \
static struct freq_attr _name = \
__ATTR(_name, 0644, show_##_name, store_##_name)
define_one_ro0400(cpuinfo_cur_freq);
define_one_ro(cpuinfo_min_freq);
define_one_ro(cpuinfo_max_freq);
define_one_ro(scaling_available_governors);
define_one_ro(scaling_driver);
define_one_ro(scaling_cur_freq);
define_one_ro(affected_cpus);
define_one_rw(scaling_min_freq);
define_one_rw(scaling_max_freq);
define_one_rw(scaling_governor);
static struct attribute * default_attrs[] = {
&cpuinfo_min_freq.attr,
&cpuinfo_max_freq.attr,
&scaling_min_freq.attr,
&scaling_max_freq.attr,
&affected_cpus.attr,
&scaling_governor.attr,
&scaling_driver.attr,
&scaling_available_governors.attr,
NULL
};
#define to_policy(k) container_of(k,struct cpufreq_policy,kobj)
#define to_attr(a) container_of(a,struct freq_attr,attr)
static ssize_t show(struct kobject * kobj, struct attribute * attr ,char * buf)
{
struct cpufreq_policy * policy = to_policy(kobj);
struct freq_attr * fattr = to_attr(attr);
ssize_t ret;
policy = cpufreq_cpu_get(policy->cpu);
if (!policy)
return -EINVAL;
ret = fattr->show ? fattr->show(policy,buf) : -EIO;
cpufreq_cpu_put(policy);
return ret;
}
static ssize_t store(struct kobject * kobj, struct attribute * attr,
const char * buf, size_t count)
{
struct cpufreq_policy * policy = to_policy(kobj);
struct freq_attr * fattr = to_attr(attr);
ssize_t ret;
policy = cpufreq_cpu_get(policy->cpu);
if (!policy)
return -EINVAL;
ret = fattr->store ? fattr->store(policy,buf,count) : -EIO;
cpufreq_cpu_put(policy);
return ret;
}
static void cpufreq_sysfs_release(struct kobject * kobj)
{
struct cpufreq_policy * policy = to_policy(kobj);
dprintk("last reference is dropped\n");
complete(&policy->kobj_unregister);
}
static struct sysfs_ops sysfs_ops = {
.show = show,
.store = store,
};
static struct kobj_type ktype_cpufreq = {
.sysfs_ops = &sysfs_ops,
.default_attrs = default_attrs,
.release = cpufreq_sysfs_release,
};
/**
* cpufreq_add_dev - add a CPU device
*
* Adds the cpufreq interface for a CPU device.
*/
static int cpufreq_add_dev (struct sys_device * sys_dev)
{
unsigned int cpu = sys_dev->id;
int ret = 0;
struct cpufreq_policy new_policy;
struct cpufreq_policy *policy;
struct freq_attr **drv_attr;
struct sys_device *cpu_sys_dev;
unsigned long flags;
unsigned int j;
#ifdef CONFIG_SMP
struct cpufreq_policy *managed_policy;
#endif
if (cpu_is_offline(cpu))
return 0;
cpufreq_debug_disable_ratelimit();
dprintk("adding CPU %u\n", cpu);
#ifdef CONFIG_SMP
/* check whether a different CPU already registered this
* CPU because it is in the same boat. */
policy = cpufreq_cpu_get(cpu);
if (unlikely(policy)) {
cpufreq_cpu_put(policy);
cpufreq_debug_enable_ratelimit();
return 0;
}
#endif
if (!try_module_get(cpufreq_driver->owner)) {
ret = -EINVAL;
goto module_out;
}
policy = kzalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
if (!policy) {
ret = -ENOMEM;
goto nomem_out;
}
policy->cpu = cpu;
policy->cpus = cpumask_of_cpu(cpu);
mutex_init(&policy->lock);
mutex_lock(&policy->lock);
init_completion(&policy->kobj_unregister);
INIT_WORK(&policy->update, handle_update, (void *)(long)cpu);
/* call driver. From then on the cpufreq must be able
* to accept all calls to ->verify and ->setpolicy for this CPU
*/
ret = cpufreq_driver->init(policy);
if (ret) {
dprintk("initialization failed\n");
mutex_unlock(&policy->lock);
goto err_out;
}
#ifdef CONFIG_SMP
for_each_cpu_mask(j, policy->cpus) {
if (cpu == j)
continue;
/* check for existing affected CPUs. They may not be aware
* of it due to CPU Hotplug.
*/
managed_policy = cpufreq_cpu_get(j);
if (unlikely(managed_policy)) {
spin_lock_irqsave(&cpufreq_driver_lock, flags);
managed_policy->cpus = policy->cpus;
cpufreq_cpu_data[cpu] = managed_policy;
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
dprintk("CPU already managed, adding link\n");
sysfs_create_link(&sys_dev->kobj,
&managed_policy->kobj, "cpufreq");
cpufreq_debug_enable_ratelimit();
mutex_unlock(&policy->lock);
ret = 0;
goto err_out_driver_exit; /* call driver->exit() */
}
}
#endif
memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
/* prepare interface data */
policy->kobj.parent = &sys_dev->kobj;
policy->kobj.ktype = &ktype_cpufreq;
strlcpy(policy->kobj.name, "cpufreq", KOBJ_NAME_LEN);
ret = kobject_register(&policy->kobj);
if (ret) {
mutex_unlock(&policy->lock);
goto err_out_driver_exit;
}
/* set up files for this cpu device */
drv_attr = cpufreq_driver->attr;
while ((drv_attr) && (*drv_attr)) {
sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
drv_attr++;
}
if (cpufreq_driver->get)
sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
if (cpufreq_driver->target)
sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
spin_lock_irqsave(&cpufreq_driver_lock, flags);
for_each_cpu_mask(j, policy->cpus)
cpufreq_cpu_data[j] = policy;
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
/* symlink affected CPUs */
for_each_cpu_mask(j, policy->cpus) {
if (j == cpu)
continue;
if (!cpu_online(j))
continue;
dprintk("CPU %u already managed, adding link\n", j);
cpufreq_cpu_get(cpu);
cpu_sys_dev = get_cpu_sysdev(j);
sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj,
"cpufreq");
}
policy->governor = NULL; /* to assure that the starting sequence is
* run in cpufreq_set_policy */
mutex_unlock(&policy->lock);
/* set default policy */
ret = cpufreq_set_policy(&new_policy);
if (ret) {
dprintk("setting policy failed\n");
goto err_out_unregister;
}
module_put(cpufreq_driver->owner);
dprintk("initialization complete\n");
cpufreq_debug_enable_ratelimit();
return 0;
err_out_unregister:
spin_lock_irqsave(&cpufreq_driver_lock, flags);
for_each_cpu_mask(j, policy->cpus)
cpufreq_cpu_data[j] = NULL;
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
kobject_unregister(&policy->kobj);
wait_for_completion(&policy->kobj_unregister);
err_out_driver_exit:
if (cpufreq_driver->exit)
cpufreq_driver->exit(policy);
err_out:
kfree(policy);
nomem_out:
module_put(cpufreq_driver->owner);
module_out:
cpufreq_debug_enable_ratelimit();
return ret;
}
/**
* cpufreq_remove_dev - remove a CPU device
*
* Removes the cpufreq interface for a CPU device.
*/
static int cpufreq_remove_dev (struct sys_device * sys_dev)
{
unsigned int cpu = sys_dev->id;
unsigned long flags;
struct cpufreq_policy *data;
#ifdef CONFIG_SMP
struct sys_device *cpu_sys_dev;
unsigned int j;
#endif
cpufreq_debug_disable_ratelimit();
dprintk("unregistering CPU %u\n", cpu);
spin_lock_irqsave(&cpufreq_driver_lock, flags);
data = cpufreq_cpu_data[cpu];
if (!data) {
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
cpufreq_debug_enable_ratelimit();
return -EINVAL;
}
cpufreq_cpu_data[cpu] = NULL;
#ifdef CONFIG_SMP
/* if this isn't the CPU which is the parent of the kobj, we
* only need to unlink, put and exit
*/
if (unlikely(cpu != data->cpu)) {
dprintk("removing link\n");
cpu_clear(cpu, data->cpus);
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
sysfs_remove_link(&sys_dev->kobj, "cpufreq");
cpufreq_cpu_put(data);
cpufreq_debug_enable_ratelimit();
return 0;
}
#endif
if (!kobject_get(&data->kobj)) {
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
cpufreq_debug_enable_ratelimit();
return -EFAULT;
}
#ifdef CONFIG_SMP
/* if we have other CPUs still registered, we need to unlink them,
* or else wait_for_completion below will lock up. Clean the
* cpufreq_cpu_data[] while holding the lock, and remove the sysfs
* links afterwards.
*/
if (unlikely(cpus_weight(data->cpus) > 1)) {
for_each_cpu_mask(j, data->cpus) {
if (j == cpu)
continue;
cpufreq_cpu_data[j] = NULL;
}
}
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
if (unlikely(cpus_weight(data->cpus) > 1)) {
for_each_cpu_mask(j, data->cpus) {
if (j == cpu)
continue;
dprintk("removing link for cpu %u\n", j);
cpu_sys_dev = get_cpu_sysdev(j);
sysfs_remove_link(&cpu_sys_dev->kobj, "cpufreq");
cpufreq_cpu_put(data);
}
}
#else
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
#endif
mutex_lock(&data->lock);
if (cpufreq_driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
mutex_unlock(&data->lock);
kobject_unregister(&data->kobj);
kobject_put(&data->kobj);
/* we need to make sure that the underlying kobj is actually
* not referenced anymore by anybody before we proceed with
* unloading.
*/
dprintk("waiting for dropping of refcount\n");
wait_for_completion(&data->kobj_unregister);
dprintk("wait complete\n");
if (cpufreq_driver->exit)
cpufreq_driver->exit(data);
kfree(data);
cpufreq_debug_enable_ratelimit();
return 0;
}
static void handle_update(void *data)
{
unsigned int cpu = (unsigned int)(long)data;
dprintk("handle_update for cpu %u called\n", cpu);
cpufreq_update_policy(cpu);
}
/**
* cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're in deep trouble.
* @cpu: cpu number
* @old_freq: CPU frequency the kernel thinks the CPU runs at
* @new_freq: CPU frequency the CPU actually runs at
*
* We adjust to current frequency first, and need to clean up later. So either call
* to cpufreq_update_policy() or schedule handle_update()).
*/
static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq, unsigned int new_freq)
{
struct cpufreq_freqs freqs;
dprintk("Warning: CPU frequency out of sync: cpufreq and timing "
"core thinks of %u, is %u kHz.\n", old_freq, new_freq);
freqs.cpu = cpu;
freqs.old = old_freq;
freqs.new = new_freq;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
}
/**
* cpufreq_quick_get - get the CPU frequency (in kHz) frpm policy->cur
* @cpu: CPU number
*
* This is the last known freq, without actually getting it from the driver.
* Return value will be same as what is shown in scaling_cur_freq in sysfs.
*/
unsigned int cpufreq_quick_get(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
unsigned int ret = 0;
if (policy) {
mutex_lock(&policy->lock);
ret = policy->cur;
mutex_unlock(&policy->lock);
cpufreq_cpu_put(policy);
}
return (ret);
}
EXPORT_SYMBOL(cpufreq_quick_get);
/**
* cpufreq_get - get the current CPU frequency (in kHz)
* @cpu: CPU number
*
* Get the CPU current (static) CPU frequency
*/
unsigned int cpufreq_get(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
unsigned int ret = 0;
if (!policy)
return 0;
if (!cpufreq_driver->get)
goto out;
mutex_lock(&policy->lock);
ret = cpufreq_driver->get(cpu);
if (ret && policy->cur && !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
/* verify no discrepancy between actual and saved value exists */
if (unlikely(ret != policy->cur)) {
cpufreq_out_of_sync(cpu, policy->cur, ret);
schedule_work(&policy->update);
}
}
mutex_unlock(&policy->lock);
out:
cpufreq_cpu_put(policy);
return (ret);
}
EXPORT_SYMBOL(cpufreq_get);
/**
* cpufreq_suspend - let the low level driver prepare for suspend
*/
static int cpufreq_suspend(struct sys_device * sysdev, pm_message_t pmsg)
{
int cpu = sysdev->id;
unsigned int ret = 0;
unsigned int cur_freq = 0;
struct cpufreq_policy *cpu_policy;
dprintk("resuming cpu %u\n", cpu);
if (!cpu_online(cpu))
return 0;
/* we may be lax here as interrupts are off. Nonetheless
* we need to grab the correct cpu policy, as to check
* whether we really run on this CPU.
*/
cpu_policy = cpufreq_cpu_get(cpu);
if (!cpu_policy)
return -EINVAL;
/* only handle each CPU group once */
if (unlikely(cpu_policy->cpu != cpu)) {
cpufreq_cpu_put(cpu_policy);
return 0;
}
if (cpufreq_driver->suspend) {
ret = cpufreq_driver->suspend(cpu_policy, pmsg);
if (ret) {
printk(KERN_ERR "cpufreq: suspend failed in ->suspend "
"step on CPU %u\n", cpu_policy->cpu);
cpufreq_cpu_put(cpu_policy);
return ret;
}
}
if (cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)
goto out;
if (cpufreq_driver->get)
cur_freq = cpufreq_driver->get(cpu_policy->cpu);
if (!cur_freq || !cpu_policy->cur) {
printk(KERN_ERR "cpufreq: suspend failed to assert current "
"frequency is what timing core thinks it is.\n");
goto out;
}
if (unlikely(cur_freq != cpu_policy->cur)) {
struct cpufreq_freqs freqs;
if (!(cpufreq_driver->flags & CPUFREQ_PM_NO_WARN))
dprintk("Warning: CPU frequency is %u, "
"cpufreq assumed %u kHz.\n",
cur_freq, cpu_policy->cur);
freqs.cpu = cpu;
freqs.old = cpu_policy->cur;
freqs.new = cur_freq;
blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
CPUFREQ_SUSPENDCHANGE, &freqs);
adjust_jiffies(CPUFREQ_SUSPENDCHANGE, &freqs);
cpu_policy->cur = cur_freq;
}
out:
cpufreq_cpu_put(cpu_policy);
return 0;
}
/**
* cpufreq_resume - restore proper CPU frequency handling after resume
*
* 1.) resume CPUfreq hardware support (cpufreq_driver->resume())
* 2.) if ->target and !CPUFREQ_CONST_LOOPS: verify we're in sync
* 3.) schedule call cpufreq_update_policy() ASAP as interrupts are
* restored.
*/
static int cpufreq_resume(struct sys_device * sysdev)
{
int cpu = sysdev->id;
unsigned int ret = 0;
struct cpufreq_policy *cpu_policy;
dprintk("resuming cpu %u\n", cpu);
if (!cpu_online(cpu))
return 0;
/* we may be lax here as interrupts are off. Nonetheless
* we need to grab the correct cpu policy, as to check
* whether we really run on this CPU.
*/
cpu_policy = cpufreq_cpu_get(cpu);
if (!cpu_policy)
return -EINVAL;
/* only handle each CPU group once */
if (unlikely(cpu_policy->cpu != cpu)) {
cpufreq_cpu_put(cpu_policy);
return 0;
}
if (cpufreq_driver->resume) {
ret = cpufreq_driver->resume(cpu_policy);
if (ret) {
printk(KERN_ERR "cpufreq: resume failed in ->resume "
"step on CPU %u\n", cpu_policy->cpu);
cpufreq_cpu_put(cpu_policy);
return ret;
}
}
if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
unsigned int cur_freq = 0;
if (cpufreq_driver->get)
cur_freq = cpufreq_driver->get(cpu_policy->cpu);
if (!cur_freq || !cpu_policy->cur) {
printk(KERN_ERR "cpufreq: resume failed to assert "
"current frequency is what timing core "
"thinks it is.\n");
goto out;
}
if (unlikely(cur_freq != cpu_policy->cur)) {
struct cpufreq_freqs freqs;
if (!(cpufreq_driver->flags & CPUFREQ_PM_NO_WARN))
dprintk("Warning: CPU frequency"
"is %u, cpufreq assumed %u kHz.\n",
cur_freq, cpu_policy->cur);
freqs.cpu = cpu;
freqs.old = cpu_policy->cur;
freqs.new = cur_freq;
blocking_notifier_call_chain(
&cpufreq_transition_notifier_list,
CPUFREQ_RESUMECHANGE, &freqs);
adjust_jiffies(CPUFREQ_RESUMECHANGE, &freqs);
cpu_policy->cur = cur_freq;
}
}
out:
schedule_work(&cpu_policy->update);
cpufreq_cpu_put(cpu_policy);
return ret;
}
static struct sysdev_driver cpufreq_sysdev_driver = {
.add = cpufreq_add_dev,
.remove = cpufreq_remove_dev,
.suspend = cpufreq_suspend,
.resume = cpufreq_resume,
};
/*********************************************************************
* NOTIFIER LISTS INTERFACE *
*********************************************************************/
/**
* cpufreq_register_notifier - register a driver with cpufreq
* @nb: notifier function to register
* @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
*
* Add a driver to one of two lists: either a list of drivers that
* are notified about clock rate changes (once before and once after
* the transition), or a list of drivers that are notified about
* changes in cpufreq policy.
*
* This function may sleep, and has the same return conditions as
* blocking_notifier_chain_register.
*/
int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
{
int ret;
switch (list) {
case CPUFREQ_TRANSITION_NOTIFIER:
ret = blocking_notifier_chain_register(
&cpufreq_transition_notifier_list, nb);
break;
case CPUFREQ_POLICY_NOTIFIER:
ret = blocking_notifier_chain_register(
&cpufreq_policy_notifier_list, nb);
break;
default:
ret = -EINVAL;
}
return ret;
}
EXPORT_SYMBOL(cpufreq_register_notifier);
/**
* cpufreq_unregister_notifier - unregister a driver with cpufreq
* @nb: notifier block to be unregistered
* @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
*
* Remove a driver from the CPU frequency notifier list.
*
* This function may sleep, and has the same return conditions as
* blocking_notifier_chain_unregister.
*/
int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
{
int ret;
switch (list) {
case CPUFREQ_TRANSITION_NOTIFIER:
ret = blocking_notifier_chain_unregister(
&cpufreq_transition_notifier_list, nb);
break;
case CPUFREQ_POLICY_NOTIFIER:
ret = blocking_notifier_chain_unregister(
&cpufreq_policy_notifier_list, nb);
break;
default:
ret = -EINVAL;
}
return ret;
}
EXPORT_SYMBOL(cpufreq_unregister_notifier);
/*********************************************************************
* GOVERNORS *
*********************************************************************/
/* Must be called with lock_cpu_hotplug held */
int __cpufreq_driver_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
int retval = -EINVAL;
dprintk("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
target_freq, relation);
if (cpu_online(policy->cpu) && cpufreq_driver->target)
retval = cpufreq_driver->target(policy, target_freq, relation);
return retval;
}
EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
int cpufreq_driver_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
int ret;
policy = cpufreq_cpu_get(policy->cpu);
if (!policy)
return -EINVAL;
lock_cpu_hotplug();
mutex_lock(&policy->lock);
ret = __cpufreq_driver_target(policy, target_freq, relation);
mutex_unlock(&policy->lock);
unlock_cpu_hotplug();
cpufreq_cpu_put(policy);
return ret;
}
EXPORT_SYMBOL_GPL(cpufreq_driver_target);
/*
* Locking: Must be called with the lock_cpu_hotplug() lock held
* when "event" is CPUFREQ_GOV_LIMITS
*/
static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event)
{
int ret;
if (!try_module_get(policy->governor->owner))
return -EINVAL;
dprintk("__cpufreq_governor for CPU %u, event %u\n", policy->cpu, event);
ret = policy->governor->governor(policy, event);
/* we keep one module reference alive for each CPU governed by this CPU */
if ((event != CPUFREQ_GOV_START) || ret)
module_put(policy->governor->owner);
if ((event == CPUFREQ_GOV_STOP) && !ret)
module_put(policy->governor->owner);
return ret;
}
int cpufreq_register_governor(struct cpufreq_governor *governor)
{
int err;
if (!governor)
return -EINVAL;
mutex_lock(&cpufreq_governor_mutex);
err = -EBUSY;
if (__find_governor(governor->name) == NULL) {
err = 0;
list_add(&governor->governor_list, &cpufreq_governor_list);
}
mutex_unlock(&cpufreq_governor_mutex);
return err;
}
EXPORT_SYMBOL_GPL(cpufreq_register_governor);
void cpufreq_unregister_governor(struct cpufreq_governor *governor)
{
if (!governor)
return;
mutex_lock(&cpufreq_governor_mutex);
list_del(&governor->governor_list);
mutex_unlock(&cpufreq_governor_mutex);
return;
}
EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
/*********************************************************************
* POLICY INTERFACE *
*********************************************************************/
/**
* cpufreq_get_policy - get the current cpufreq_policy
* @policy: struct cpufreq_policy into which the current cpufreq_policy is written
*
* Reads the current cpufreq policy.
*/
int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
{
struct cpufreq_policy *cpu_policy;
if (!policy)
return -EINVAL;
cpu_policy = cpufreq_cpu_get(cpu);
if (!cpu_policy)
return -EINVAL;
mutex_lock(&cpu_policy->lock);
memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
mutex_unlock(&cpu_policy->lock);
cpufreq_cpu_put(cpu_policy);
return 0;
}
EXPORT_SYMBOL(cpufreq_get_policy);
/*
* Locking: Must be called with the lock_cpu_hotplug() lock held
*/
static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_policy *policy)
{
int ret = 0;
cpufreq_debug_disable_ratelimit();
dprintk("setting new policy for CPU %u: %u - %u kHz\n", policy->cpu,
policy->min, policy->max);
memcpy(&policy->cpuinfo, &data->cpuinfo, sizeof(struct cpufreq_cpuinfo));
if (policy->min > data->min && policy->min > policy->max) {
ret = -EINVAL;
goto error_out;
}
/* verify the cpu speed can be set within this limit */
ret = cpufreq_driver->verify(policy);
if (ret)
goto error_out;
/* adjust if necessary - all reasons */
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_ADJUST, policy);
/* adjust if necessary - hardware incompatibility*/
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_INCOMPATIBLE, policy);
/* verify the cpu speed can be set within this limit,
which might be different to the first one */
ret = cpufreq_driver->verify(policy);
if (ret)
goto error_out;
/* notification of the new policy */
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_NOTIFY, policy);
data->min = policy->min;
data->max = policy->max;
dprintk("new min and max freqs are %u - %u kHz\n", data->min, data->max);
if (cpufreq_driver->setpolicy) {
data->policy = policy->policy;
dprintk("setting range\n");
ret = cpufreq_driver->setpolicy(policy);
} else {
if (policy->governor != data->governor) {
/* save old, working values */
struct cpufreq_governor *old_gov = data->governor;
dprintk("governor switch\n");
/* end old governor */
if (data->governor)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
/* start new governor */
data->governor = policy->governor;
if (__cpufreq_governor(data, CPUFREQ_GOV_START)) {
/* new governor failed, so re-start old one */
dprintk("starting governor %s failed\n", data->governor->name);
if (old_gov) {
data->governor = old_gov;
__cpufreq_governor(data, CPUFREQ_GOV_START);
}
ret = -EINVAL;
goto error_out;
}
/* might be a policy change, too, so fall through */
}
dprintk("governor: change or update limits\n");
__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
}
error_out:
cpufreq_debug_enable_ratelimit();
return ret;
}
/**
* cpufreq_set_policy - set a new CPUFreq policy
* @policy: policy to be set.
*
* Sets a new CPU frequency and voltage scaling policy.
*/
int cpufreq_set_policy(struct cpufreq_policy *policy)
{
int ret = 0;
struct cpufreq_policy *data;
if (!policy)
return -EINVAL;
data = cpufreq_cpu_get(policy->cpu);
if (!data)
return -EINVAL;
lock_cpu_hotplug();
/* lock this CPU */
mutex_lock(&data->lock);
ret = __cpufreq_set_policy(data, policy);
data->user_policy.min = data->min;
data->user_policy.max = data->max;
data->user_policy.policy = data->policy;
data->user_policy.governor = data->governor;
mutex_unlock(&data->lock);
unlock_cpu_hotplug();
cpufreq_cpu_put(data);
return ret;
}
EXPORT_SYMBOL(cpufreq_set_policy);
/**
* cpufreq_update_policy - re-evaluate an existing cpufreq policy
* @cpu: CPU which shall be re-evaluated
*
* Usefull for policy notifiers which have different necessities
* at different times.
*/
int cpufreq_update_policy(unsigned int cpu)
{
struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
struct cpufreq_policy policy;
int ret = 0;
if (!data)
return -ENODEV;
lock_cpu_hotplug();
mutex_lock(&data->lock);
dprintk("updating policy for CPU %u\n", cpu);
memcpy(&policy, data, sizeof(struct cpufreq_policy));
policy.min = data->user_policy.min;
policy.max = data->user_policy.max;
policy.policy = data->user_policy.policy;
policy.governor = data->user_policy.governor;
/* BIOS might change freq behind our back
-> ask driver for current freq and notify governors about a change */
if (cpufreq_driver->get) {
policy.cur = cpufreq_driver->get(cpu);
if (!data->cur) {
dprintk("Driver did not initialize current freq");
data->cur = policy.cur;
} else {
if (data->cur != policy.cur)
cpufreq_out_of_sync(cpu, data->cur, policy.cur);
}
}
ret = __cpufreq_set_policy(data, &policy);
mutex_unlock(&data->lock);
unlock_cpu_hotplug();
cpufreq_cpu_put(data);
return ret;
}
EXPORT_SYMBOL(cpufreq_update_policy);
#ifdef CONFIG_HOTPLUG_CPU
static int cpufreq_cpu_callback(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
unsigned int cpu = (unsigned long)hcpu;
struct cpufreq_policy *policy;
struct sys_device *sys_dev;
sys_dev = get_cpu_sysdev(cpu);
if (sys_dev) {
switch (action) {
case CPU_ONLINE:
cpufreq_add_dev(sys_dev);
break;
case CPU_DOWN_PREPARE:
/*
* We attempt to put this cpu in lowest frequency
* possible before going down. This will permit
* hardware-managed P-State to switch other related
* threads to min or higher speeds if possible.
*/
policy = cpufreq_cpu_data[cpu];
if (policy) {
cpufreq_driver_target(policy, policy->min,
CPUFREQ_RELATION_H);
}
break;
case CPU_DEAD:
cpufreq_remove_dev(sys_dev);
break;
}
}
return NOTIFY_OK;
}
static struct notifier_block __cpuinitdata cpufreq_cpu_notifier =
{
.notifier_call = cpufreq_cpu_callback,
};
#endif /* CONFIG_HOTPLUG_CPU */
/*********************************************************************
* REGISTER / UNREGISTER CPUFREQ DRIVER *
*********************************************************************/
/**
* cpufreq_register_driver - register a CPU Frequency driver
* @driver_data: A struct cpufreq_driver containing the values#
* submitted by the CPU Frequency driver.
*
* Registers a CPU Frequency driver to this core code. This code
* returns zero on success, -EBUSY when another driver got here first
* (and isn't unregistered in the meantime).
*
*/
int cpufreq_register_driver(struct cpufreq_driver *driver_data)
{
unsigned long flags;
int ret;
if (!driver_data || !driver_data->verify || !driver_data->init ||
((!driver_data->setpolicy) && (!driver_data->target)))
return -EINVAL;
dprintk("trying to register driver %s\n", driver_data->name);
if (driver_data->setpolicy)
driver_data->flags |= CPUFREQ_CONST_LOOPS;
spin_lock_irqsave(&cpufreq_driver_lock, flags);
if (cpufreq_driver) {
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
return -EBUSY;
}
cpufreq_driver = driver_data;
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
ret = sysdev_driver_register(&cpu_sysdev_class,&cpufreq_sysdev_driver);
if ((!ret) && !(cpufreq_driver->flags & CPUFREQ_STICKY)) {
int i;
ret = -ENODEV;
/* check for at least one working CPU */
for (i=0; i<NR_CPUS; i++)
if (cpufreq_cpu_data[i])
ret = 0;
/* if all ->init() calls failed, unregister */
if (ret) {
dprintk("no CPU initialized for driver %s\n", driver_data->name);
sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
spin_lock_irqsave(&cpufreq_driver_lock, flags);
cpufreq_driver = NULL;
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
}
}
if (!ret) {
register_hotcpu_notifier(&cpufreq_cpu_notifier);
dprintk("driver %s up and running\n", driver_data->name);
cpufreq_debug_enable_ratelimit();
}
return (ret);
}
EXPORT_SYMBOL_GPL(cpufreq_register_driver);
/**
* cpufreq_unregister_driver - unregister the current CPUFreq driver
*
* Unregister the current CPUFreq driver. Only call this if you have
* the right to do so, i.e. if you have succeeded in initialising before!
* Returns zero if successful, and -EINVAL if the cpufreq_driver is
* currently not initialised.
*/
int cpufreq_unregister_driver(struct cpufreq_driver *driver)
{
unsigned long flags;
cpufreq_debug_disable_ratelimit();
if (!cpufreq_driver || (driver != cpufreq_driver)) {
cpufreq_debug_enable_ratelimit();
return -EINVAL;
}
dprintk("unregistering driver %s\n", driver->name);
sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
spin_lock_irqsave(&cpufreq_driver_lock, flags);
cpufreq_driver = NULL;
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
return 0;
}
EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
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