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/export.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/pm_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 <linux/of.h>
#include "governor.h"

#define MAX(a,b)	((a > b) ? a : b)
#define MIN(a,b)	((a < b) ? a : b)

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 (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);
}

static unsigned long find_available_min_freq(struct devfreq *devfreq)
{
	struct dev_pm_opp *opp;
	unsigned long min_freq = 0;

	opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &min_freq);
	if (IS_ERR(opp))
		min_freq = 0;
	else
		dev_pm_opp_put(opp);

	return min_freq;
}

static unsigned long find_available_max_freq(struct devfreq *devfreq)
{
	struct dev_pm_opp *opp;
	unsigned long max_freq = ULONG_MAX;

	opp = dev_pm_opp_find_freq_floor(devfreq->dev.parent, &max_freq);
	if (IS_ERR(opp))
		max_freq = 0;
	else
		dev_pm_opp_put(opp);

	return max_freq;
}

/**
 * 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;
}

static int set_freq_table(struct devfreq *devfreq)
{
	struct devfreq_dev_profile *profile = devfreq->profile;
	struct dev_pm_opp *opp;
	unsigned long freq;
	int i, count;

	/* Initialize the freq_table from OPP table */
	count = dev_pm_opp_get_opp_count(devfreq->dev.parent);
	if (count <= 0)
		return -EINVAL;

	profile->max_state = count;
	profile->freq_table = devm_kcalloc(devfreq->dev.parent,
					profile->max_state,
					sizeof(*profile->freq_table),
					GFP_KERNEL);
	if (!profile->freq_table) {
		profile->max_state = 0;
		return -ENOMEM;
	}

	for (i = 0, freq = 0; i < profile->max_state; i++, freq++) {
		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
		if (IS_ERR(opp)) {
			devm_kfree(devfreq->dev.parent, profile->freq_table);
			profile->max_state = 0;
			return PTR_ERR(opp);
		}
		dev_pm_opp_put(opp);
		profile->freq_table[i] = freq;
	}

	return 0;
}

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

	cur_time = jiffies;

	/* Immediately exit if previous_freq is not initialized yet. */
	if (!devfreq->previous_freq)
		goto out;

	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] +=
			 cur_time - devfreq->last_stat_updated;

	lev = devfreq_get_freq_level(devfreq, freq);
	if (lev < 0) {
		ret = lev;
		goto out;
	}

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

out:
	devfreq->last_stat_updated = cur_time;
	return ret;
}
EXPORT_SYMBOL(devfreq_update_status);

/**
 * 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 (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);
}

static int devfreq_notify_transition(struct devfreq *devfreq,
		struct devfreq_freqs *freqs, unsigned int state)
{
	if (!devfreq)
		return -EINVAL;

	switch (state) {
	case DEVFREQ_PRECHANGE:
		srcu_notifier_call_chain(&devfreq->transition_notifier_list,
				DEVFREQ_PRECHANGE, freqs);
		break;

	case DEVFREQ_POSTCHANGE:
		srcu_notifier_call_chain(&devfreq->transition_notifier_list,
				DEVFREQ_POSTCHANGE, freqs);
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

/* 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)
{
	struct devfreq_freqs freqs;
	unsigned long freq, cur_freq, min_freq, max_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 = devfreq->governor->get_target_freq(devfreq, &freq);
	if (err)
		return err;

	/*
	 * Adjust the frequency with user freq, QoS and available freq.
	 *
	 * List from the highest priority
	 * max_freq
	 * min_freq
	 */
	max_freq = MIN(devfreq->scaling_max_freq, devfreq->max_freq);
	min_freq = MAX(devfreq->scaling_min_freq, devfreq->min_freq);

	if (min_freq && freq < min_freq) {
		freq = min_freq;
		flags &= ~DEVFREQ_FLAG_LEA