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linux/drivers/cpufreq/cpufreq.c
Ashok Raj 90d45d17f3 [PATCH] cpu hotplug: fix locking in cpufreq drivers 
When calling target drivers to set frequency, we take cpucontrol lock.
When we modified the code to accomodate CPU hotplug, there was an attempt
to take a double lock of cpucontrol leading to a deadlock.  Since the
current thread context is already holding the cpucontrol lock, we dont need
to make another attempt to acquire it.

Now we leave a trace in current->flags indicating current thread already is
under cpucontrol lock held, so we dont attempt to do this another time.

Thanks to Andrew Morton for the beating:-)

From: Brice Goglin <Brice.Goglin@ens-lyon.org>

  Build fix

(akpm: this patch is still unpleasant.  Ashok continues to look for a cleaner
solution, doesn't he?  ;))

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Brice Goglin <Brice.Goglin@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-09 07:55:50 -08:00

1561 lines
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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
*
* 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/config.h>
#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>
#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);
static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci);
/**
* 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 struct notifier_block *cpufreq_policy_notifier_list;
static struct notifier_block *cpufreq_transition_notifier_list;
static DECLARE_RWSEM (cpufreq_notifier_rwsem);
static LIST_HEAD(cpufreq_governor_list);
static DECLARE_MUTEX (cpufreq_governor_sem);
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 inline 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 inline 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 inline 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)
{
BUG_ON(irqs_disabled());
freqs->flags = cpufreq_driver->flags;
dprintk("notification %u of frequency transition to %u kHz\n", state, freqs->new);
down_read(&cpufreq_notifier_rwsem);
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 ((likely(cpufreq_cpu_data[freqs->cpu])) &&
(likely(cpufreq_cpu_data[freqs->cpu]->cpu == freqs->cpu)) &&
(likely(cpufreq_cpu_data[freqs->cpu]->cur)) &&
(unlikely(freqs->old != cpufreq_cpu_data[freqs->cpu]->cur)))
{
dprintk(KERN_WARNING "Warning: CPU frequency is %u, "
"cpufreq assumed %u kHz.\n", freqs->old, cpufreq_cpu_data[freqs->cpu]->cur);
freqs->old = cpufreq_cpu_data[freqs->cpu]->cur;
}
}
notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_PRECHANGE, freqs);
adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
break;
case CPUFREQ_POSTCHANGE:
adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_POSTCHANGE, freqs);
if ((likely(cpufreq_cpu_data[freqs->cpu])) &&
(likely(cpufreq_cpu_data[freqs->cpu]->cpu == freqs->cpu)))
cpufreq_cpu_data[freqs->cpu]->cur = freqs->new;
break;
}
up_read(&cpufreq_notifier_rwsem);
}
EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
/*********************************************************************
* SYSFS INTERFACE *
*********************************************************************/
/**
* cpufreq_parse_governor - parse a governor string
*/
static int cpufreq_parse_governor (char *str_governor, unsigned int *policy,
struct cpufreq_governor **governor)
{
if (!cpufreq_driver)
return -EINVAL;
if (cpufreq_driver->setpolicy) {
if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
*policy = CPUFREQ_POLICY_PERFORMANCE;
return 0;
} else if (!strnicmp(str_governor, "powersave", CPUFREQ_NAME_LEN)) {
*policy = CPUFREQ_POLICY_POWERSAVE;
return 0;
}
return -EINVAL;
} else {
struct cpufreq_governor *t;
down(&cpufreq_governor_sem);
if (!cpufreq_driver || !cpufreq_driver->target)
goto out;
list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
if (!strnicmp(str_governor,t->name,CPUFREQ_NAME_LEN)) {
*governor = t;
up(&cpufreq_governor_sem);
return 0;
}
}
out:
up(&cpufreq_governor_sem);
}
return -EINVAL;
}
EXPORT_SYMBOL_GPL(cpufreq_parse_governor);
/* 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);
/**
* 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; \
\
ret = cpufreq_set_policy(&new_policy); \
\
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;
ret = cpufreq_set_policy(&new_policy);
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;
unsigned long flags;
unsigned int j;
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)) {
dprintk("CPU already managed, adding link\n");
sysfs_create_link(&sys_dev->kobj, &policy->kobj, "cpufreq");
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);
init_MUTEX_LOCKED(&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");
goto err_out;
}
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)
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);
policy->governor = NULL; /* to assure that the starting sequence is
* run in cpufreq_set_policy */
up(&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;
struct sys_device *cpu_sys_dev;
#ifdef CONFIG_SMP
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");
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
down(&data->lock);
if (cpufreq_driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
up(&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(KERN_WARNING "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_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;
down(&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);
}
}
up(&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(KERN_DEBUG "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;
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(KERN_WARNING "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;
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
* notifier_chain_register.
*/
int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
{
int ret;
down_write(&cpufreq_notifier_rwsem);
switch (list) {
case CPUFREQ_TRANSITION_NOTIFIER:
ret = notifier_chain_register(&cpufreq_transition_notifier_list, nb);
break;
case CPUFREQ_POLICY_NOTIFIER:
ret = notifier_chain_register(&cpufreq_policy_notifier_list, nb);
break;
default:
ret = -EINVAL;
}
up_write(&cpufreq_notifier_rwsem);
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
* notifier_chain_unregister.
*/
int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
{
int ret;
down_write(&cpufreq_notifier_rwsem);
switch (list) {
case CPUFREQ_TRANSITION_NOTIFIER:
ret = notifier_chain_unregister(&cpufreq_transition_notifier_list, nb);
break;
case CPUFREQ_POLICY_NOTIFIER:
ret = notifier_chain_unregister(&cpufreq_policy_notifier_list, nb);
break;
default:
ret = -EINVAL;
}
up_write(&cpufreq_notifier_rwsem);
return ret;
}
EXPORT_SYMBOL(cpufreq_unregister_notifier);
/*********************************************************************
* GOVERNORS *
*********************************************************************/
int __cpufreq_driver_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
int retval = -EINVAL;
/*
* If we are already in context of hotplug thread, we dont need to
* acquire the hotplug lock. Otherwise acquire cpucontrol to prevent
* hotplug from removing this cpu that we are working on.
*/
if (!current_in_cpu_hotplug())
lock_cpu_hotplug();
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);
if (!current_in_cpu_hotplug())
unlock_cpu_hotplug();
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;
down(&policy->lock);
ret = __cpufreq_driver_target(policy, target_freq, relation);
up(&policy->lock);
cpufreq_cpu_put(policy);
return ret;
}
EXPORT_SYMBOL_GPL(cpufreq_driver_target);
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_governor(unsigned int cpu, unsigned int event)
{
int ret = 0;
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
if (!policy)
return -EINVAL;
down(&policy->lock);
ret = __cpufreq_governor(policy, event);
up(&policy->lock);
cpufreq_cpu_put(policy);
return ret;
}
EXPORT_SYMBOL_GPL(cpufreq_governor);
int cpufreq_register_governor(struct cpufreq_governor *governor)
{
struct cpufreq_governor *t;
if (!governor)
return -EINVAL;
down(&cpufreq_governor_sem);
list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
if (!strnicmp(governor->name,t->name,CPUFREQ_NAME_LEN)) {
up(&cpufreq_governor_sem);
return -EBUSY;
}
}
list_add(&governor->governor_list, &cpufreq_governor_list);
up(&cpufreq_governor_sem);
return 0;
}
EXPORT_SYMBOL_GPL(cpufreq_register_governor);
void cpufreq_unregister_governor(struct cpufreq_governor *governor)
{
if (!governor)
return;
down(&cpufreq_governor_sem);
list_del(&governor->governor_list);
up(&cpufreq_governor_sem);
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;
down(&cpu_policy->lock);
memcpy(policy, cpu_policy, sizeof(struct cpufreq_policy));
up(&cpu_policy->lock);
cpufreq_cpu_put(cpu_policy);
return 0;
}
EXPORT_SYMBOL(cpufreq_get_policy);
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));
/* verify the cpu speed can be set within this limit */
ret = cpufreq_driver->verify(policy);
if (ret)
goto error_out;
down_read(&cpufreq_notifier_rwsem);
/* adjust if necessary - all reasons */
notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_ADJUST,
policy);
/* adjust if necessary - hardware incompatibility*/
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) {
up_read(&cpufreq_notifier_rwsem);
goto error_out;
}
/* notification of the new policy */
notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY,
policy);
up_read(&cpufreq_notifier_rwsem);
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 this CPU */
down(&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;
up(&data->lock);
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;
down(&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;
ret = __cpufreq_set_policy(data, &policy);
up(&data->lock);
cpufreq_cpu_put(data);
return ret;
}
EXPORT_SYMBOL(cpufreq_update_policy);
static int __cpuinit 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 cpufreq_cpu_notifier =
{
.notifier_call = cpufreq_cpu_callback,
};
/*********************************************************************
* 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_cpu_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_cpu_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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