cpufreq.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,167 行 · 第 1/2 页

/*
 *  linux/drivers/cpufreq/cpufreq.c
 *
 *  Copyright (C) 2001 Russell King
 *            (C) 2002 - 2003 Dominik Brodowski <[e-mail]>
 *
 * 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>

/**
 * 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 spinlock_t		cpufreq_driver_lock = SPIN_LOCK_UNLOCKED;

/* 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);

static 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;
}

static void cpufreq_cpu_put(struct cpufreq_policy *data)
{
	kobject_put(&data->kobj);
	module_put(cpufreq_driver->owner);
}

/*********************************************************************
 *            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;
	}
	if ((val == CPUFREQ_PRECHANGE  && ci->old < ci->new) ||
	    (val == CPUFREQ_POSTCHANGE && ci->old > ci->new) ||
	    (val == CPUFREQ_RESUMECHANGE))
		loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq, 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;

	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]->cur)) &&
			    (unlikely(freqs->old != cpufreq_cpu_data[freqs->cpu]->cur)))
			{
				printk(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]))
			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
 */
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;
}


#define define_one_ro(_name) \
struct freq_attr _name = { \
	.attr = { .name = __stringify(_name), .mode = 0444 }, \
	.show = show_##_name, \
}

#define define_one_ro0400(_name) \
struct freq_attr _name = { \
	.attr = { .name = __stringify(_name), .mode = 0400 }, \
	.show = show_##_name, \
}

#define define_one_rw(_name) \
struct freq_attr _name = { \
	.attr = { .name = __stringify(_name), .mode = 0644 }, \
	.show = show_##_name, \
	.store = 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_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,
	&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) : 0;
	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) : 0;
	cpufreq_cpu_put(policy);
	return ret;
}

static void cpufreq_sysfs_release(struct kobject * kobj)
{
	struct cpufreq_policy * policy = to_policy(kobj);
	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;

	if (!try_module_get(cpufreq_driver->owner))
		return -EINVAL;

	policy = kmalloc(sizeof(struct cpufreq_policy), GFP_KERNEL);
	if (!policy) {
		ret = -ENOMEM;
		goto nomem_out;
	}
	memset(policy, 0, sizeof(struct cpufreq_policy));

	policy->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)
		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;

	/* 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);
	cpufreq_cpu_data[cpu] = 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)
		goto err_out_unregister;

	module_put(cpufreq_driver->owner);
	return 0;


err_out_unregister:
	spin_lock_irqsave(&cpufreq_driver_lock, flags);
	cpufreq_cpu_data[cpu] = NULL;
	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);

	kobject_unregister(&policy->kobj);
	wait_for_completion(&policy->kobj_unregister);

err_out:
	kfree(policy);

nomem_out:
	module_put(cpufreq_driver->owner);
	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;

	spin_lock_irqsave(&cpufreq_driver_lock, flags);
	data = cpufreq_cpu_data[cpu];

	if (!data) {
		spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
		return -EINVAL;
	}
	cpufreq_cpu_data[cpu] = NULL;
	spin_unlock_irqrestore(&cpufreq_driver_lock, flags);

	if (!kobject_get(&data->kobj))
		return -EFAULT;

	if (cpufreq_driver->target)
		__cpufreq_governor(data, CPUFREQ_GOV_STOP);

	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.
	 */
	wait_for_completion(&data->kobj_unregister);

	if (cpufreq_driver->exit)
		cpufreq_driver->exit(data);

	kfree(data);

	return 0;
}


static void handle_update(void *data)