devfreq.c 31.1 KB
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/*
 * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
 *	    for Non-CPU Devices.
 *
 * Copyright (C) 2011 Samsung Electronics
 *	MyungJoo Ham <myungjoo.ham@samsung.com>
 *
 * 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/sched.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/stat.h>
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#include <linux/pm_opp.h>
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#include <linux/devfreq.h>
#include <linux/workqueue.h>
#include <linux/platform_device.h>
#include <linux/list.h>
#include <linux/printk.h>
#include <linux/hrtimer.h>
#include "governor.h"

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static struct class *devfreq_class;
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/*
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 * devfreq core provides delayed work based load monitoring helper
 * functions. Governors can use these or can implement their own
 * monitoring mechanism.
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 */
static struct workqueue_struct *devfreq_wq;

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/* The list of all device-devfreq governors */
static LIST_HEAD(devfreq_governor_list);
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/* The list of all device-devfreq */
static LIST_HEAD(devfreq_list);
static DEFINE_MUTEX(devfreq_list_lock);

/**
 * find_device_devfreq() - find devfreq struct using device pointer
 * @dev:	device pointer used to lookup device devfreq.
 *
 * Search the list of device devfreqs and return the matched device's
 * devfreq info. devfreq_list_lock should be held by the caller.
 */
static struct devfreq *find_device_devfreq(struct device *dev)
{
	struct devfreq *tmp_devfreq;

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	if (IS_ERR_OR_NULL(dev)) {
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		pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
		return ERR_PTR(-EINVAL);
	}
	WARN(!mutex_is_locked(&devfreq_list_lock),
	     "devfreq_list_lock must be locked.");

	list_for_each_entry(tmp_devfreq, &devfreq_list, node) {
		if (tmp_devfreq->dev.parent == dev)
			return tmp_devfreq;
	}

	return ERR_PTR(-ENODEV);
}

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/**
 * devfreq_get_freq_level() - Lookup freq_table for the frequency
 * @devfreq:	the devfreq instance
 * @freq:	the target frequency
 */
static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
{
	int lev;

	for (lev = 0; lev < devfreq->profile->max_state; lev++)
		if (freq == devfreq->profile->freq_table[lev])
			return lev;

	return -EINVAL;
}

/**
 * devfreq_update_status() - Update statistics of devfreq behavior
 * @devfreq:	the devfreq instance
 * @freq:	the update target frequency
 */
static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
{
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	int lev, prev_lev, ret = 0;
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	unsigned long cur_time;

	cur_time = jiffies;
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	prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq);
	if (prev_lev < 0) {
		ret = prev_lev;
		goto out;
	}

	devfreq->time_in_state[prev_lev] +=
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			 cur_time - devfreq->last_stat_updated;
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	lev = devfreq_get_freq_level(devfreq, freq);
	if (lev < 0) {
		ret = lev;
		goto out;
	}

	if (lev != prev_lev) {
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		devfreq->trans_table[(prev_lev *
				devfreq->profile->max_state) + lev]++;
		devfreq->total_trans++;
	}

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out:
	devfreq->last_stat_updated = cur_time;
	return ret;
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}

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/**
 * find_devfreq_governor() - find devfreq governor from name
 * @name:	name of the governor
 *
 * Search the list of devfreq governors and return the matched
 * governor's pointer. devfreq_list_lock should be held by the caller.
 */
static struct devfreq_governor *find_devfreq_governor(const char *name)
{
	struct devfreq_governor *tmp_governor;

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	if (IS_ERR_OR_NULL(name)) {
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		pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
		return ERR_PTR(-EINVAL);
	}
	WARN(!mutex_is_locked(&devfreq_list_lock),
	     "devfreq_list_lock must be locked.");

	list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
		if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
			return tmp_governor;
	}

	return ERR_PTR(-ENODEV);
}

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/* Load monitoring helper functions for governors use */

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/**
 * update_devfreq() - Reevaluate the device and configure frequency.
 * @devfreq:	the devfreq instance.
 *
 * Note: Lock devfreq->lock before calling update_devfreq
 *	 This function is exported for governors.
 */
int update_devfreq(struct devfreq *devfreq)
{
	unsigned long freq;
	int err = 0;
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	u32 flags = 0;
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	if (!mutex_is_locked(&devfreq->lock)) {
		WARN(true, "devfreq->lock must be locked by the caller.\n");
		return -EINVAL;
	}

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	if (!devfreq->governor)
		return -EINVAL;

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	/* Reevaluate the proper frequency */
	err = devfreq->governor->get_target_freq(devfreq, &freq);
	if (err)
		return err;

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	/*
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	 * Adjust the frequency with user freq and QoS.
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	 *
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	 * List from the highest priority
	 * max_freq
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	 * min_freq
	 */

	if (devfreq->min_freq && freq < devfreq->min_freq) {
		freq = devfreq->min_freq;
		flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
	}
	if (devfreq->max_freq && freq > devfreq->max_freq) {
		freq = devfreq->max_freq;
		flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
	}

	err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
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	if (err)
		return err;

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	if (devfreq->profile->freq_table)
		if (devfreq_update_status(devfreq, freq))
			dev_err(&devfreq->dev,
				"Couldn't update frequency transition information.\n");

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	devfreq->previous_freq = freq;
	return err;
}
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EXPORT_SYMBOL(update_devfreq);
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/**
 * devfreq_monitor() - Periodically poll devfreq objects.
 * @work:	the work struct used to run devfreq_monitor periodically.
 *
 */
static void devfreq_monitor(struct work_struct *work)
{
	int err;
	struct devfreq *devfreq = container_of(work,
					struct devfreq, work.work);

	mutex_lock(&devfreq->lock);
	err = update_devfreq(devfreq);
	if (err)
		dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err);

	queue_delayed_work(devfreq_wq, &devfreq->work,
				msecs_to_jiffies(devfreq->profile->polling_ms));
	mutex_unlock(&devfreq->lock);
}

/**
 * devfreq_monitor_start() - Start load monitoring of devfreq instance
 * @devfreq:	the devfreq instance.
 *
 * Helper function for starting devfreq device load monitoing. By
 * default delayed work based monitoring is supported. Function
 * to be called from governor in response to DEVFREQ_GOV_START
 * event when device is added to devfreq framework.
 */
void devfreq_monitor_start(struct devfreq *devfreq)
{
	INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor);
	if (devfreq->profile->polling_ms)
		queue_delayed_work(devfreq_wq, &devfreq->work,
			msecs_to_jiffies(devfreq->profile->polling_ms));
}
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EXPORT_SYMBOL(devfreq_monitor_start);
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/**
 * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance
 * @devfreq:	the devfreq instance.
 *
 * Helper function to stop devfreq device load monitoing. Function
 * to be called from governor in response to DEVFREQ_GOV_STOP
 * event when device is removed from devfreq framework.
 */
void devfreq_monitor_stop(struct devfreq *devfreq)
{
	cancel_delayed_work_sync(&devfreq->work);
}
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EXPORT_SYMBOL(devfreq_monitor_stop);
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/**
 * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance
 * @devfreq:	the devfreq instance.
 *
 * Helper function to suspend devfreq device load monitoing. Function
 * to be called from governor in response to DEVFREQ_GOV_SUSPEND
 * event or when polling interval is set to zero.
 *
 * Note: Though this function is same as devfreq_monitor_stop(),
 * intentionally kept separate to provide hooks for collecting
 * transition statistics.
 */
void devfreq_monitor_suspend(struct devfreq *devfreq)
{
	mutex_lock(&devfreq->lock);
	if (devfreq->stop_polling) {
		mutex_unlock(&devfreq->lock);
		return;
	}

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	devfreq_update_status(devfreq, devfreq->previous_freq);
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	devfreq->stop_polling = true;
	mutex_unlock(&devfreq->lock);
	cancel_delayed_work_sync(&devfreq->work);
}
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EXPORT_SYMBOL(devfreq_monitor_suspend);
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/**
 * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance
 * @devfreq:    the devfreq instance.
 *
 * Helper function to resume devfreq device load monitoing. Function
 * to be called from governor in response to DEVFREQ_GOV_RESUME
 * event or when polling interval is set to non-zero.
 */
void devfreq_monitor_resume(struct devfreq *devfreq)
{
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	unsigned long freq;

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	mutex_lock(&devfreq->lock);
	if (!devfreq->stop_polling)
		goto out;

	if (!delayed_work_pending(&devfreq->work) &&
			devfreq->profile->polling_ms)
		queue_delayed_work(devfreq_wq, &devfreq->work,
			msecs_to_jiffies(devfreq->profile->polling_ms));
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	devfreq->last_stat_updated = jiffies;
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	devfreq->stop_polling = false;

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	if (devfreq->profile->get_cur_freq &&
		!devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
		devfreq->previous_freq = freq;

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out:
	mutex_unlock(&devfreq->lock);
}
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EXPORT_SYMBOL(devfreq_monitor_resume);
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/**
 * devfreq_interval_update() - Update device devfreq monitoring interval
 * @devfreq:    the devfreq instance.
 * @delay:      new polling interval to be set.
 *
 * Helper function to set new load monitoring polling interval. Function
 * to be called from governor in response to DEVFREQ_GOV_INTERVAL event.
 */
void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay)
{
	unsigned int cur_delay = devfreq->profile->polling_ms;
	unsigned int new_delay = *delay;

	mutex_lock(&devfreq->lock);
	devfreq->profile->polling_ms = new_delay;

	if (devfreq->stop_polling)
		goto out;

	/* if new delay is zero, stop polling */
	if (!new_delay) {
		mutex_unlock(&devfreq->lock);
		cancel_delayed_work_sync(&devfreq->work);
		return;
	}

	/* if current delay is zero, start polling with new delay */
	if (!cur_delay) {
		queue_delayed_work(devfreq_wq, &devfreq->work,
			msecs_to_jiffies(devfreq->profile->polling_ms));
		goto out;
	}

	/* if current delay is greater than new delay, restart polling */
	if (cur_delay > new_delay) {
		mutex_unlock(&devfreq->lock);
		cancel_delayed_work_sync(&devfreq->work);
		mutex_lock(&devfreq->lock);
		if (!devfreq->stop_polling)
			queue_delayed_work(devfreq_wq, &devfreq->work,
			      msecs_to_jiffies(devfreq->profile->polling_ms));
	}
out:
	mutex_unlock(&devfreq->lock);
}
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EXPORT_SYMBOL(devfreq_interval_update);
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/**
 * devfreq_notifier_call() - Notify that the device frequency requirements
 *			   has been changed out of devfreq framework.
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 * @nb:		the notifier_block (supposed to be devfreq->nb)
 * @type:	not used
 * @devp:	not used
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 *
 * Called by a notifier that uses devfreq->nb.
 */
static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type,
				 void *devp)
{
	struct devfreq *devfreq = container_of(nb, struct devfreq, nb);
	int ret;

	mutex_lock(&devfreq->lock);
	ret = update_devfreq(devfreq);
	mutex_unlock(&devfreq->lock);

	return ret;
}

/**
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 * _remove_devfreq() - Remove devfreq from the list and release its resources.
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 * @devfreq:	the devfreq struct
 */
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static void _remove_devfreq(struct devfreq *devfreq)
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{
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	mutex_lock(&devfreq_list_lock);
	if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) {
		mutex_unlock(&devfreq_list_lock);
		dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
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		return;
	}
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	list_del(&devfreq->node);
	mutex_unlock(&devfreq_list_lock);
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	if (devfreq->governor)
		devfreq->governor->event_handler(devfreq,
						 DEVFREQ_GOV_STOP, NULL);
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	if (devfreq->profile->exit)
		devfreq->profile->exit(devfreq->dev.parent);

	mutex_destroy(&devfreq->lock);
	kfree(devfreq);
}

/**
 * devfreq_dev_release() - Callback for struct device to release the device.
 * @dev:	the devfreq device
 *
 * This calls _remove_devfreq() if _remove_devfreq() is not called.
 */
static void devfreq_dev_release(struct device *dev)
{
	struct devfreq *devfreq = to_devfreq(dev);

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	_remove_devfreq(devfreq);
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}

/**
 * devfreq_add_device() - Add devfreq feature to the device
 * @dev:	the device to add devfreq feature.
 * @profile:	device-specific profile to run devfreq.
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 * @governor_name:	name of the policy to choose frequency.
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 * @data:	private data for the governor. The devfreq framework does not
 *		touch this value.
 */
struct devfreq *devfreq_add_device(struct device *dev,
				   struct devfreq_dev_profile *profile,
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				   const char *governor_name,
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				   void *data)
{
	struct devfreq *devfreq;
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	struct devfreq_governor *governor;
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	int err = 0;

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	if (!dev || !profile || !governor_name) {
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		dev_err(dev, "%s: Invalid parameters.\n", __func__);
		return ERR_PTR(-EINVAL);
	}

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	mutex_lock(&devfreq_list_lock);
	devfreq = find_device_devfreq(dev);
	mutex_unlock(&devfreq_list_lock);
	if (!IS_ERR(devfreq)) {
		dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__);
		err = -EINVAL;
		goto err_out;
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	}

	devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL);
	if (!devfreq) {
		dev_err(dev, "%s: Unable to create devfreq for the device\n",
			__func__);
		err = -ENOMEM;
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		goto err_out;
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	}

	mutex_init(&devfreq->lock);
	mutex_lock(&devfreq->lock);
	devfreq->dev.parent = dev;
	devfreq->dev.class = devfreq_class;
	devfreq->dev.release = devfreq_dev_release;
	devfreq->profile = profile;
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	strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
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	devfreq->previous_freq = profile->initial_freq;
	devfreq->data = data;
	devfreq->nb.notifier_call = devfreq_notifier_call;

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	devfreq->trans_table =	devm_kzalloc(dev, sizeof(unsigned int) *
						devfreq->profile->max_state *
						devfreq->profile->max_state,
						GFP_KERNEL);
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	devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned long) *
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						devfreq->profile->max_state,
						GFP_KERNEL);
	devfreq->last_stat_updated = jiffies;

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	dev_set_name(&devfreq->dev, "%s", dev_name(dev));
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	err = device_register(&devfreq->dev);
	if (err) {
		put_device(&devfreq->dev);
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		mutex_unlock(&devfreq->lock);
G
Geliang Tang 已提交
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		goto err_out;
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	}

	mutex_unlock(&devfreq->lock);

	mutex_lock(&devfreq_list_lock);
	list_add(&devfreq->node, &devfreq_list);

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	governor = find_devfreq_governor(devfreq->governor_name);
	if (!IS_ERR(governor))
		devfreq->governor = governor;
	if (devfreq->governor)
		err = devfreq->governor->event_handler(devfreq,
					DEVFREQ_GOV_START, NULL);
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	mutex_unlock(&devfreq_list_lock);
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	if (err) {
		dev_err(dev, "%s: Unable to start governor for the device\n",
			__func__);
		goto err_init;
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	}
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	return devfreq;

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err_init:
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	list_del(&devfreq->node);
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	device_unregister(&devfreq->dev);
	kfree(devfreq);
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err_out:
	return ERR_PTR(err);
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}
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EXPORT_SYMBOL(devfreq_add_device);
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/**
 * devfreq_remove_device() - Remove devfreq feature from a device.
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 * @devfreq:	the devfreq instance to be removed
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 *
 * The opposite of devfreq_add_device().
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 */
int devfreq_remove_device(struct devfreq *devfreq)
{
	if (!devfreq)
		return -EINVAL;

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	device_unregister(&devfreq->dev);
	put_device(&devfreq->dev);
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	return 0;
}
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EXPORT_SYMBOL(devfreq_remove_device);
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static int devm_devfreq_dev_match(struct device *dev, void *res, void *data)
{
	struct devfreq **r = res;

	if (WARN_ON(!r || !*r))
		return 0;

	return *r == data;
}

static void devm_devfreq_dev_release(struct device *dev, void *res)
{
	devfreq_remove_device(*(struct devfreq **)res);
}

/**
 * devm_devfreq_add_device() - Resource-managed devfreq_add_device()
 * @dev:	the device to add devfreq feature.
 * @profile:	device-specific profile to run devfreq.
 * @governor_name:	name of the policy to choose frequency.
 * @data:	private data for the governor. The devfreq framework does not
 *		touch this value.
 *
 * This function manages automatically the memory of devfreq device using device
 * resource management and simplify the free operation for memory of devfreq
 * device.
 */
struct devfreq *devm_devfreq_add_device(struct device *dev,
					struct devfreq_dev_profile *profile,
					const char *governor_name,
					void *data)
{
	struct devfreq **ptr, *devfreq;

	ptr = devres_alloc(devm_devfreq_dev_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	devfreq = devfreq_add_device(dev, profile, governor_name, data);
	if (IS_ERR(devfreq)) {
		devres_free(ptr);
		return ERR_PTR(-ENOMEM);
	}

	*ptr = devfreq;
	devres_add(dev, ptr);

	return devfreq;
}
EXPORT_SYMBOL(devm_devfreq_add_device);

/**
 * devm_devfreq_remove_device() - Resource-managed devfreq_remove_device()
 * @dev:	the device to add devfreq feature.
 * @devfreq:	the devfreq instance to be removed
 */
void devm_devfreq_remove_device(struct device *dev, struct devfreq *devfreq)
{
	WARN_ON(devres_release(dev, devm_devfreq_dev_release,
			       devm_devfreq_dev_match, devfreq));
}
EXPORT_SYMBOL(devm_devfreq_remove_device);

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/**
 * devfreq_suspend_device() - Suspend devfreq of a device.
 * @devfreq: the devfreq instance to be suspended
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 *
 * This function is intended to be called by the pm callbacks
 * (e.g., runtime_suspend, suspend) of the device driver that
 * holds the devfreq.
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 */
int devfreq_suspend_device(struct devfreq *devfreq)
{
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	if (!devfreq)
		return -EINVAL;

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	if (!devfreq->governor)
		return 0;

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	return devfreq->governor->event_handler(devfreq,
				DEVFREQ_GOV_SUSPEND, NULL);
}
EXPORT_SYMBOL(devfreq_suspend_device);

/**
 * devfreq_resume_device() - Resume devfreq of a device.
 * @devfreq: the devfreq instance to be resumed
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 *
 * This function is intended to be called by the pm callbacks
 * (e.g., runtime_resume, resume) of the device driver that
 * holds the devfreq.
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 */
int devfreq_resume_device(struct devfreq *devfreq)
{
	if (!devfreq)
		return -EINVAL;

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	if (!devfreq->governor)
		return 0;

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	return devfreq->governor->event_handler(devfreq,
				DEVFREQ_GOV_RESUME, NULL);
}
EXPORT_SYMBOL(devfreq_resume_device);

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/**
 * devfreq_add_governor() - Add devfreq governor
 * @governor:	the devfreq governor to be added
 */
int devfreq_add_governor(struct devfreq_governor *governor)
{
	struct devfreq_governor *g;
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	struct devfreq *devfreq;
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	int err = 0;

	if (!governor) {
		pr_err("%s: Invalid parameters.\n", __func__);
		return -EINVAL;
	}

	mutex_lock(&devfreq_list_lock);
	g = find_devfreq_governor(governor->name);
	if (!IS_ERR(g)) {
		pr_err("%s: governor %s already registered\n", __func__,
		       g->name);
		err = -EINVAL;
		goto err_out;
	}
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	list_add(&governor->node, &devfreq_governor_list);

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	list_for_each_entry(devfreq, &devfreq_list, node) {
		int ret = 0;
		struct device *dev = devfreq->dev.parent;

		if (!strncmp(devfreq->governor_name, governor->name,
			     DEVFREQ_NAME_LEN)) {
			/* The following should never occur */
			if (devfreq->governor) {
				dev_warn(dev,
					 "%s: Governor %s already present\n",
					 __func__, devfreq->governor->name);
				ret = devfreq->governor->event_handler(devfreq,
							DEVFREQ_GOV_STOP, NULL);
				if (ret) {
					dev_warn(dev,
						 "%s: Governor %s stop = %d\n",
						 __func__,
						 devfreq->governor->name, ret);
				}
				/* Fall through */
			}
			devfreq->governor = governor;
			ret = devfreq->governor->event_handler(devfreq,
						DEVFREQ_GOV_START, NULL);
			if (ret) {
				dev_warn(dev, "%s: Governor %s start=%d\n",
					 __func__, devfreq->governor->name,
					 ret);
			}
705 706 707
		}
	}

708 709
err_out:
	mutex_unlock(&devfreq_list_lock);
710

711 712 713
	return err;
}
EXPORT_SYMBOL(devfreq_add_governor);
714

715 716 717 718 719 720 721
/**
 * devfreq_remove_device() - Remove devfreq feature from a device.
 * @governor:	the devfreq governor to be removed
 */
int devfreq_remove_governor(struct devfreq_governor *governor)
{
	struct devfreq_governor *g;
722
	struct devfreq *devfreq;
723 724 725 726 727 728 729 730 731 732 733
	int err = 0;

	if (!governor) {
		pr_err("%s: Invalid parameters.\n", __func__);
		return -EINVAL;
	}

	mutex_lock(&devfreq_list_lock);
	g = find_devfreq_governor(governor->name);
	if (IS_ERR(g)) {
		pr_err("%s: governor %s not registered\n", __func__,
734
		       governor->name);
735
		err = PTR_ERR(g);
736 737
		goto err_out;
	}
738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760
	list_for_each_entry(devfreq, &devfreq_list, node) {
		int ret;
		struct device *dev = devfreq->dev.parent;

		if (!strncmp(devfreq->governor_name, governor->name,
			     DEVFREQ_NAME_LEN)) {
			/* we should have a devfreq governor! */
			if (!devfreq->governor) {
				dev_warn(dev, "%s: Governor %s NOT present\n",
					 __func__, governor->name);
				continue;
				/* Fall through */
			}
			ret = devfreq->governor->event_handler(devfreq,
						DEVFREQ_GOV_STOP, NULL);
			if (ret) {
				dev_warn(dev, "%s: Governor %s stop=%d\n",
					 __func__, devfreq->governor->name,
					 ret);
			}
			devfreq->governor = NULL;
		}
	}
761 762 763 764 765 766

	list_del(&governor->node);
err_out:
	mutex_unlock(&devfreq_list_lock);

	return err;
767
}
768
EXPORT_SYMBOL(devfreq_remove_governor);
769

770
static ssize_t governor_show(struct device *dev,
771 772
			     struct device_attribute *attr, char *buf)
{
773 774 775
	if (!to_devfreq(dev)->governor)
		return -EINVAL;

776 777 778
	return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
}

779
static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796
			      const char *buf, size_t count)
{
	struct devfreq *df = to_devfreq(dev);
	int ret;
	char str_governor[DEVFREQ_NAME_LEN + 1];
	struct devfreq_governor *governor;

	ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
	if (ret != 1)
		return -EINVAL;

	mutex_lock(&devfreq_list_lock);
	governor = find_devfreq_governor(str_governor);
	if (IS_ERR(governor)) {
		ret = PTR_ERR(governor);
		goto out;
	}
797 798
	if (df->governor == governor) {
		ret = 0;
799
		goto out;
800
	}
801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822

	if (df->governor) {
		ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
		if (ret) {
			dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
				 __func__, df->governor->name, ret);
			goto out;
		}
	}
	df->governor = governor;
	strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
	ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
	if (ret)
		dev_warn(dev, "%s: Governor %s not started(%d)\n",
			 __func__, df->governor->name, ret);
out:
	mutex_unlock(&devfreq_list_lock);

	if (!ret)
		ret = count;
	return ret;
}
823 824 825 826 827
static DEVICE_ATTR_RW(governor);

static ssize_t available_governors_show(struct device *d,
					struct device_attribute *attr,
					char *buf)
828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845
{
	struct devfreq_governor *tmp_governor;
	ssize_t count = 0;

	mutex_lock(&devfreq_list_lock);
	list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
				   "%s ", tmp_governor->name);
	mutex_unlock(&devfreq_list_lock);

	/* Truncate the trailing space */
	if (count)
		count--;

	count += sprintf(&buf[count], "\n");

	return count;
}
846
static DEVICE_ATTR_RO(available_governors);
847

848 849
static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
850 851 852 853 854 855 856 857 858 859
{
	unsigned long freq;
	struct devfreq *devfreq = to_devfreq(dev);

	if (devfreq->profile->get_cur_freq &&
		!devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
			return sprintf(buf, "%lu\n", freq);

	return sprintf(buf, "%lu\n", devfreq->previous_freq);
}
860
static DEVICE_ATTR_RO(cur_freq);
861

862 863
static ssize_t target_freq_show(struct device *dev,
				struct device_attribute *attr, char *buf)
864 865 866
{
	return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
}
867
static DEVICE_ATTR_RO(target_freq);
868

869
static ssize_t polling_interval_show(struct device *dev,
870 871 872 873 874
				     struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
}

875
static ssize_t polling_interval_store(struct device *dev,
876 877 878 879 880 881 882
				      struct device_attribute *attr,
				      const char *buf, size_t count)
{
	struct devfreq *df = to_devfreq(dev);
	unsigned int value;
	int ret;

883 884 885
	if (!df->governor)
		return -EINVAL;

886 887
	ret = sscanf(buf, "%u", &value);
	if (ret != 1)
888
		return -EINVAL;
889

890
	df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
891 892 893 894
	ret = count;

	return ret;
}
895
static DEVICE_ATTR_RW(polling_interval);
896

897
static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
898 899 900 901 902 903 904 905 906
			      const char *buf, size_t count)
{
	struct devfreq *df = to_devfreq(dev);
	unsigned long value;
	int ret;
	unsigned long max;

	ret = sscanf(buf, "%lu", &value);
	if (ret != 1)
907
		return -EINVAL;
908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923

	mutex_lock(&df->lock);
	max = df->max_freq;
	if (value && max && value > max) {
		ret = -EINVAL;
		goto unlock;
	}

	df->min_freq = value;
	update_devfreq(df);
	ret = count;
unlock:
	mutex_unlock(&df->lock);
	return ret;
}

924
static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
925 926 927 928 929
			     char *buf)
{
	return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
}

930
static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
931 932 933 934 935 936 937 938 939
			      const char *buf, size_t count)
{
	struct devfreq *df = to_devfreq(dev);
	unsigned long value;
	int ret;
	unsigned long min;

	ret = sscanf(buf, "%lu", &value);
	if (ret != 1)
940
		return -EINVAL;
941 942 943 944 945 946 947 948 949 950 951 952 953 954 955

	mutex_lock(&df->lock);
	min = df->min_freq;
	if (value && min && value < min) {
		ret = -EINVAL;
		goto unlock;
	}

	df->max_freq = value;
	update_devfreq(df);
	ret = count;
unlock:
	mutex_unlock(&df->lock);
	return ret;
}
956
static DEVICE_ATTR_RW(min_freq);
957

958
static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
959 960 961 962
			     char *buf)
{
	return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
}
963
static DEVICE_ATTR_RW(max_freq);
964

965 966 967
static ssize_t available_frequencies_show(struct device *d,
					  struct device_attribute *attr,
					  char *buf)
968 969 970
{
	struct devfreq *df = to_devfreq(d);
	struct device *dev = df->dev.parent;
971
	struct dev_pm_opp *opp;
972 973 974 975 976
	ssize_t count = 0;
	unsigned long freq = 0;

	rcu_read_lock();
	do {
977
		opp = dev_pm_opp_find_freq_ceil(dev, &freq);
978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994
		if (IS_ERR(opp))
			break;

		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
				   "%lu ", freq);
		freq++;
	} while (1);
	rcu_read_unlock();

	/* Truncate the trailing space */
	if (count)
		count--;

	count += sprintf(&buf[count], "\n");

	return count;
}
995
static DEVICE_ATTR_RO(available_frequencies);
996

997 998
static ssize_t trans_stat_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
999 1000 1001
{
	struct devfreq *devfreq = to_devfreq(dev);
	ssize_t len;
1002
	int i, j;
1003 1004
	unsigned int max_state = devfreq->profile->max_state;

1005 1006
	if (!devfreq->stop_polling &&
			devfreq_update_status(devfreq, devfreq->previous_freq))
1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036
		return 0;

	len = sprintf(buf, "   From  :   To\n");
	len += sprintf(buf + len, "         :");
	for (i = 0; i < max_state; i++)
		len += sprintf(buf + len, "%8u",
				devfreq->profile->freq_table[i]);

	len += sprintf(buf + len, "   time(ms)\n");

	for (i = 0; i < max_state; i++) {
		if (devfreq->profile->freq_table[i]
					== devfreq->previous_freq) {
			len += sprintf(buf + len, "*");
		} else {
			len += sprintf(buf + len, " ");
		}
		len += sprintf(buf + len, "%8u:",
				devfreq->profile->freq_table[i]);
		for (j = 0; j < max_state; j++)
			len += sprintf(buf + len, "%8u",
				devfreq->trans_table[(i * max_state) + j]);
		len += sprintf(buf + len, "%10u\n",
			jiffies_to_msecs(devfreq->time_in_state[i]));
	}

	len += sprintf(buf + len, "Total transition : %u\n",
					devfreq->total_trans);
	return len;
}
1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049
static DEVICE_ATTR_RO(trans_stat);

static struct attribute *devfreq_attrs[] = {
	&dev_attr_governor.attr,
	&dev_attr_available_governors.attr,
	&dev_attr_cur_freq.attr,
	&dev_attr_available_frequencies.attr,
	&dev_attr_target_freq.attr,
	&dev_attr_polling_interval.attr,
	&dev_attr_min_freq.attr,
	&dev_attr_max_freq.attr,
	&dev_attr_trans_stat.attr,
	NULL,
1050
};
1051
ATTRIBUTE_GROUPS(devfreq);
1052

1053 1054 1055 1056 1057 1058 1059
static int __init devfreq_init(void)
{
	devfreq_class = class_create(THIS_MODULE, "devfreq");
	if (IS_ERR(devfreq_class)) {
		pr_err("%s: couldn't create class\n", __FILE__);
		return PTR_ERR(devfreq_class);
	}
1060 1061

	devfreq_wq = create_freezable_workqueue("devfreq_wq");
1062
	if (!devfreq_wq) {
1063 1064
		class_destroy(devfreq_class);
		pr_err("%s: couldn't create workqueue\n", __FILE__);
1065
		return -ENOMEM;
1066
	}
1067
	devfreq_class->dev_groups = devfreq_groups;
1068

1069 1070 1071 1072 1073 1074 1075
	return 0;
}
subsys_initcall(devfreq_init);

static void __exit devfreq_exit(void)
{
	class_destroy(devfreq_class);
1076
	destroy_workqueue(devfreq_wq);
1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087
}
module_exit(devfreq_exit);

/*
 * The followings are helper functions for devfreq user device drivers with
 * OPP framework.
 */

/**
 * devfreq_recommended_opp() - Helper function to get proper OPP for the
 *			     freq value given to target callback.
1088 1089 1090
 * @dev:	The devfreq user device. (parent of devfreq)
 * @freq:	The frequency given to target function
 * @flags:	Flags handed from devfreq framework.
1091
 *
1092 1093 1094 1095 1096
 * Locking: This function must be called under rcu_read_lock(). opp is a rcu
 * protected pointer. The reason for the same is that the opp pointer which is
 * returned will remain valid for use with opp_get_{voltage, freq} only while
 * under the locked area. The pointer returned must be used prior to unlocking
 * with rcu_read_unlock() to maintain the integrity of the pointer.
1097
 */
1098 1099 1100
struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
					   unsigned long *freq,
					   u32 flags)
1101
{
1102
	struct dev_pm_opp *opp;
1103

1104 1105
	if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
		/* The freq is an upper bound. opp should be lower */
1106
		opp = dev_pm_opp_find_freq_floor(dev, freq);
1107 1108

		/* If not available, use the closest opp */
1109
		if (opp == ERR_PTR(-ERANGE))
1110
			opp = dev_pm_opp_find_freq_ceil(dev, freq);
1111 1112
	} else {
		/* The freq is an lower bound. opp should be higher */
1113
		opp = dev_pm_opp_find_freq_ceil(dev, freq);
1114 1115

		/* If not available, use the closest opp */
1116
		if (opp == ERR_PTR(-ERANGE))
1117
			opp = dev_pm_opp_find_freq_floor(dev, freq);
1118 1119
	}

1120 1121
	return opp;
}
1122
EXPORT_SYMBOL(devfreq_recommended_opp);
1123 1124 1125 1126 1127

/**
 * devfreq_register_opp_notifier() - Helper function to get devfreq notified
 *				   for any changes in the OPP availability
 *				   changes
1128 1129
 * @dev:	The devfreq user device. (parent of devfreq)
 * @devfreq:	The devfreq object.
1130 1131 1132
 */
int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
{
1133 1134
	struct srcu_notifier_head *nh;
	int ret = 0;
1135

1136
	rcu_read_lock();
1137
	nh = dev_pm_opp_get_notifier(dev);
1138
	if (IS_ERR(nh))
1139 1140 1141 1142 1143 1144
		ret = PTR_ERR(nh);
	rcu_read_unlock();
	if (!ret)
		ret = srcu_notifier_chain_register(nh, &devfreq->nb);

	return ret;
1145
}
1146
EXPORT_SYMBOL(devfreq_register_opp_notifier);
1147 1148 1149 1150 1151

/**
 * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
 *				     notified for any changes in the OPP
 *				     availability changes anymore.
1152 1153
 * @dev:	The devfreq user device. (parent of devfreq)
 * @devfreq:	The devfreq object.
1154 1155 1156 1157 1158 1159
 *
 * At exit() callback of devfreq_dev_profile, this must be included if
 * devfreq_recommended_opp is used.
 */
int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
{
1160 1161
	struct srcu_notifier_head *nh;
	int ret = 0;
1162

1163
	rcu_read_lock();
1164
	nh = dev_pm_opp_get_notifier(dev);
1165
	if (IS_ERR(nh))
1166 1167 1168 1169 1170 1171
		ret = PTR_ERR(nh);
	rcu_read_unlock();
	if (!ret)
		ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);

	return ret;
1172
}
1173
EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1174

1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222
static void devm_devfreq_opp_release(struct device *dev, void *res)
{
	devfreq_unregister_opp_notifier(dev, *(struct devfreq **)res);
}

/**
 * devm_ devfreq_register_opp_notifier()
 *		- Resource-managed devfreq_register_opp_notifier()
 * @dev:	The devfreq user device. (parent of devfreq)
 * @devfreq:	The devfreq object.
 */
int devm_devfreq_register_opp_notifier(struct device *dev,
				       struct devfreq *devfreq)
{
	struct devfreq **ptr;
	int ret;

	ptr = devres_alloc(devm_devfreq_opp_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return -ENOMEM;

	ret = devfreq_register_opp_notifier(dev, devfreq);
	if (ret) {
		devres_free(ptr);
		return ret;
	}

	*ptr = devfreq;
	devres_add(dev, ptr);

	return 0;
}
EXPORT_SYMBOL(devm_devfreq_register_opp_notifier);

/**
 * devm_devfreq_unregister_opp_notifier()
 *		- Resource-managed devfreq_unregister_opp_notifier()
 * @dev:	The devfreq user device. (parent of devfreq)
 * @devfreq:	The devfreq object.
 */
void devm_devfreq_unregister_opp_notifier(struct device *dev,
					 struct devfreq *devfreq)
{
	WARN_ON(devres_release(dev, devm_devfreq_opp_release,
			       devm_devfreq_dev_match, devfreq));
}
EXPORT_SYMBOL(devm_devfreq_unregister_opp_notifier);

1223 1224 1225
MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
MODULE_DESCRIPTION("devfreq class support");
MODULE_LICENSE("GPL");