cpufreq.c

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

{
	unsigned int cpu = (unsigned int)(long)data;
	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;

	printk(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_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;

	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;

	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;

			printk(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,
	.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;
	lock_cpu_hotplug();
	if (cpu_online(policy->cpu))
		retval = cpufreq_driver->target(policy, target_freq, relation);
	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)
{
	unsigned 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 = -EINVAL;

	if (!try_module_get(policy->governor->owner))
		return -EINVAL;

	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;

	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;

	if (cpufreq_driver->setpolicy) {
		data->policy = policy->policy;
		ret = cpufreq_driver->setpolicy(policy);
	} else {
		if (policy->governor != data->governor) {
			/* save old, working values */
			struct cpufreq_governor *old_gov = data->governor;

			/* 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 */
				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 */
		}
		__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
	}

 error_out:
	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);

	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);


/*********************************************************************
 *               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;

	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) {
			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);
		}
	}

	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;

	if (!cpufreq_driver || (driver != cpufreq_driver))
		return -EINVAL;

	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);

	return 0;
}
EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);