path: root/drivers/devfreq/devfreq.c

/*
 * 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>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/opp.h>
#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"

static struct class *devfreq_class;

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

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

	if (unlikely(IS_ERR_OR_NULL(dev))) {
		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);
}

/**
 * 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)
{
	int lev, prev_lev;
	unsigned long cur_time;

	lev = devfreq_get_freq_level(devfreq, freq);
	if (lev < 0)
		return lev;

	cur_time = jiffies;
	devfreq->time_in_state[lev] +=
			 cur_time - devfreq->last_stat_updated;
	if (freq != devfreq->previous_freq) {
		prev_lev = devfreq_get_freq_level(devfreq,
						devfreq->previous_freq);
		devfreq->trans_table[(prev_lev *
				devfreq->profile->max_state) + lev]++;
		devfreq->total_trans++;
	}
	devfreq->last_stat_updated = cur_time;

	return 0;
}

/**
 * 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;

	if (unlikely(IS_ERR_OR_NULL(name))) {
		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);
}

/* Load monitoring helper functions for governors use */

/**
 * 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;
	u32 flags = 0;

	if (!mutex_is_locked(&devfreq->lock)) {
		WARN(true, "devfreq->lock must be locked by the caller.\n");
		return -EINVAL;
	}

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

	/* Reevaluate the proper frequency */
	err