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);
	devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) *
						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);
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		goto err_dev;
	}

	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);
err_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);
			}
706 707 708
		}
	}

709 710
err_out:
	mutex_unlock(&devfreq_list_lock);
711

712 713 714
	return err;
}
EXPORT_SYMBOL(devfreq_add_governor);
715

716 717 718 719 720 721 722
/**
 * 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;
723
	struct devfreq *devfreq;
724 725 726 727 728 729 730 731 732 733 734
	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__,
735
		       governor->name);
736
		err = PTR_ERR(g);
737 738
		goto err_out;
	}
739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761
	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;
		}
	}
762 763 764 765 766 767

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

	return err;
768
}
769
EXPORT_SYMBOL(devfreq_remove_governor);
770

771
static ssize_t governor_show(struct device *dev,
772 773
			     struct device_attribute *attr, char *buf)
{
774 775 776
	if (!to_devfreq(dev)->governor)
		return -EINVAL;

777 778 779
	return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
}

780
static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821
			      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;
	}
	if (df->governor == governor)
		goto out;

	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;
}
822 823 824 825 826
static DEVICE_ATTR_RW(governor);

static ssize_t available_governors_show(struct device *d,
					struct device_attribute *attr,
					char *buf)
827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844
{
	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;
}
845
static DEVICE_ATTR_RO(available_governors);
846

847 848
static ssize_t cur_freq_show(struct device *dev, struct device_attribute *attr,
			     char *buf)
849 850 851 852 853 854 855 856 857 858
{
	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);
}
859
static DEVICE_ATTR_RO(cur_freq);
860

861 862
static ssize_t target_freq_show(struct device *dev,
				struct device_attribute *attr, char *buf)
863 864 865
{
	return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
}
866
static DEVICE_ATTR_RO(target_freq);
867

868
static ssize_t polling_interval_show(struct device *dev,
869 870 871 872 873
				     struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
}

874
static ssize_t polling_interval_store(struct device *dev,
875 876 877 878 879 880 881
				      struct device_attribute *attr,
				      const char *buf, size_t count)
{
	struct devfreq *df = to_devfreq(dev);
	unsigned int value;
	int ret;

882 883 884
	if (!df->governor)
		return -EINVAL;

885 886
	ret = sscanf(buf, "%u", &value);
	if (ret != 1)
887
		return -EINVAL;
888

889
	df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value);
890 891 892 893
	ret = count;

	return ret;
}
894
static DEVICE_ATTR_RW(polling_interval);
895

896
static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr,
897 898 899 900 901 902 903 904 905
			      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)
906
		return -EINVAL;
907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922

	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;
}

923
static ssize_t min_freq_show(struct device *dev, struct device_attribute *attr,
924 925 926 927 928
			     char *buf)
{
	return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq);
}

929
static ssize_t max_freq_store(struct device *dev, struct device_attribute *attr,
930 931 932 933 934 935 936 937 938
			      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)
939
		return -EINVAL;
940 941 942 943 944 945 946 947 948 949 950 951 952 953 954

	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;
}
955
static DEVICE_ATTR_RW(min_freq);
956

957
static ssize_t max_freq_show(struct device *dev, struct device_attribute *attr,
958 959 960 961
			     char *buf)
{
	return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
}
962
static DEVICE_ATTR_RW(max_freq);
963

964 965 966
static ssize_t available_frequencies_show(struct device *d,
					  struct device_attribute *attr,
					  char *buf)
967 968 969
{
	struct devfreq *df = to_devfreq(d);
	struct device *dev = df->dev.parent;
970
	struct dev_pm_opp *opp;
971 972 973 974 975
	ssize_t count = 0;
	unsigned long freq = 0;

	rcu_read_lock();
	do {
976
		opp = dev_pm_opp_find_freq_ceil(dev, &freq);
977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993
		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;
}
994
static DEVICE_ATTR_RO(available_frequencies);
995

996 997
static ssize_t trans_stat_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
998 999 1000
{
	struct devfreq *devfreq = to_devfreq(dev);
	ssize_t len;
1001
	int i, j;
1002 1003
	unsigned int max_state = devfreq->profile->max_state;

1004 1005
	if (!devfreq->stop_polling &&
			devfreq_update_status(devfreq, devfreq->previous_freq))
1006 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
		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;
}
1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048
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,
1049
};
1050
ATTRIBUTE_GROUPS(devfreq);
1051

1052 1053 1054 1055 1056 1057 1058
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);
	}
1059 1060

	devfreq_wq = create_freezable_workqueue("devfreq_wq");
1061
	if (!devfreq_wq) {
1062 1063
		class_destroy(devfreq_class);
		pr_err("%s: couldn't create workqueue\n", __FILE__);
1064
		return -ENOMEM;
1065
	}
1066
	devfreq_class->dev_groups = devfreq_groups;
1067

1068 1069 1070 1071 1072 1073 1074
	return 0;
}
subsys_initcall(devfreq_init);

static void __exit devfreq_exit(void)
{
	class_destroy(devfreq_class);
1075
	destroy_workqueue(devfreq_wq);
1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086
}
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.
1087 1088 1089
 * @dev:	The devfreq user device. (parent of devfreq)
 * @freq:	The frequency given to target function
 * @flags:	Flags handed from devfreq framework.
1090
 *
1091 1092 1093 1094 1095
 * 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.
1096
 */
1097 1098 1099
struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
					   unsigned long *freq,
					   u32 flags)
1100
{
1101
	struct dev_pm_opp *opp;
1102

1103 1104
	if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
		/* The freq is an upper bound. opp should be lower */
1105
		opp = dev_pm_opp_find_freq_floor(dev, freq);
1106 1107

		/* If not available, use the closest opp */
1108
		if (opp == ERR_PTR(-ERANGE))
1109
			opp = dev_pm_opp_find_freq_ceil(dev, freq);
1110 1111
	} else {
		/* The freq is an lower bound. opp should be higher */
1112
		opp = dev_pm_opp_find_freq_ceil(dev, freq);
1113 1114

		/* If not available, use the closest opp */
1115
		if (opp == ERR_PTR(-ERANGE))
1116
			opp = dev_pm_opp_find_freq_floor(dev, freq);
1117 1118
	}

1119 1120
	return opp;
}
1121
EXPORT_SYMBOL(devfreq_recommended_opp);
1122 1123 1124 1125 1126

/**
 * devfreq_register_opp_notifier() - Helper function to get devfreq notified
 *				   for any changes in the OPP availability
 *				   changes
1127 1128
 * @dev:	The devfreq user device. (parent of devfreq)
 * @devfreq:	The devfreq object.
1129 1130 1131
 */
int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
{
1132 1133
	struct srcu_notifier_head *nh;
	int ret = 0;
1134

1135
	rcu_read_lock();
1136
	nh = dev_pm_opp_get_notifier(dev);
1137
	if (IS_ERR(nh))
1138 1139 1140 1141 1142 1143
		ret = PTR_ERR(nh);
	rcu_read_unlock();
	if (!ret)
		ret = srcu_notifier_chain_register(nh, &devfreq->nb);

	return ret;
1144
}
1145
EXPORT_SYMBOL(devfreq_register_opp_notifier);
1146 1147 1148 1149 1150

/**
 * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq
 *				     notified for any changes in the OPP
 *				     availability changes anymore.
1151 1152
 * @dev:	The devfreq user device. (parent of devfreq)
 * @devfreq:	The devfreq object.
1153 1154 1155 1156 1157 1158
 *
 * 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)
{
1159 1160
	struct srcu_notifier_head *nh;
	int ret = 0;
1161

1162
	rcu_read_lock();
1163
	nh = dev_pm_opp_get_notifier(dev);
1164
	if (IS_ERR(nh))
1165 1166 1167 1168 1169 1170
		ret = PTR_ERR(nh);
	rcu_read_unlock();
	if (!ret)
		ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);

	return ret;
1171
}
1172
EXPORT_SYMBOL(devfreq_unregister_opp_notifier);
1173

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
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);

1222 1223 1224
MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
MODULE_DESCRIPTION("devfreq class support");
MODULE_LICENSE("GPL");