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// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/drivers/devfreq/governor_passive.c
*
* Copyright (C) 2016 Samsung Electronics
* Author: Chanwoo Choi <cw00.choi@samsung.com>
* Author: MyungJoo Ham <myungjoo.ham@samsung.com>
*/
#include <linux/module.h>
#include <linux/device.h>
#include <linux/devfreq.h>
#include "governor.h"
static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
unsigned long *freq)
{
struct devfreq_passive_data *p_data
= (struct devfreq_passive_data *)devfreq->data;
struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
unsigned long child_freq = ULONG_MAX;
struct dev_pm_opp *opp;
int i, count, ret = 0;
/*
* If the devfreq device with passive governor has the specific method
* to determine the next frequency, should use the get_target_freq()
* of struct devfreq_passive_data.
*/
if (p_data->get_target_freq) {
ret = p_data->get_target_freq(devfreq, freq);
goto out;
}
/*
* If the parent and passive devfreq device uses the OPP table,
* get the next frequency by using the OPP table.
*/
/*
* - parent devfreq device uses the governors except for passive.
* - passive devfreq device uses the passive governor.
*
* Each devfreq has the OPP table. After deciding the new frequency
* from the governor of parent devfreq device, the passive governor
* need to get the index of new frequency on OPP table of parent
* device. And then the index is used for getting the suitable
* new frequency for passive devfreq device.
*/
if (!devfreq->profile || !devfreq->profile->freq_table
|| devfreq->profile->max_state <= 0)
return -EINVAL;
/*
* The passive governor have to get the correct frequency from OPP
* list of parent device. Because in this case, *freq is temporary
* value which is decided by ondemand governor.
*/
opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0);
if (IS_ERR(opp)) {
ret = PTR_ERR(opp);
goto out;
}
dev_pm_opp_put(opp);
/*
* Get the OPP table's index of decided freqeuncy by governor
* of parent device.
*/
for (i = 0; i < parent_devfreq->profile->max_state; i++)
if (parent_devfreq->profile->freq_table[i] == *freq)
break;
if (i == parent_devfreq->profile->max_state) {
ret = -EINVAL;
goto out;
}
/* Get the suitable frequency by using index of parent device. */
if (i < devfreq->profile->max_state) {
child_freq = devfreq->profile->freq_table[i];
} else {
count = devfreq->profile->max_state;
child_freq = devfreq->profile->freq_table[count - 1];
}
/* Return the suitable frequency for passive device. */
*freq = child_freq;
out:
return ret;
}
static int devfreq_passive_notifier_call(struct notifier_block *nb,
unsigned long event, void *ptr)
{
struct devfreq_passive_data *data
= container_of(nb, struct devfreq_passive_data, nb);
struct devfreq *devfreq = (struct devfreq *)data->this;
struct devfreq *parent = (struct devfreq *)data->parent;
struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr;
unsigned long freq = freqs->new;
int ret = 0;
mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
switch (event) {
case DEVFREQ_PRECHANGE:
if (parent->previous_freq > freq)
ret = devfreq_update_target(devfreq, freq);
break;
case DEVFREQ_POSTCHANGE:
if (parent->previous_freq < freq)
ret = devfreq_update_target(devfreq, freq);
break;
}
mutex_unlock(&devfreq->lock);
if (ret < 0)
dev_warn(&devfreq->dev,
"failed to update devfreq using passive governor\n");
return NOTIFY_DONE;
}
static int devfreq_passive_event_handler(struct devfreq *devfreq,
unsigned int event, void *data)
{
struct devfreq_passive_data *p_data
= (struct devfreq_passive_data *)devfreq->data;
struct devfreq *parent = (struct devfreq *)p_data->parent;
struct notifier_block *nb = &p_data->nb;
int ret = 0;
if (!parent)
return -EPROBE_DEFER;
switch (event) {
case DEVFREQ_GOV_START:
if (!p_data->this)
p_data->this = devfreq;
nb->notifier_call = devfreq_passive_notifier_call;
ret = devfreq_register_notifier(parent, nb,
DEVFREQ_TRANSITION_NOTIFIER);
break;
case DEVFREQ_GOV_STOP:
WARN_ON(devfreq_unregister_notifier(parent, nb,
DEVFREQ_TRANSITION_NOTIFIER));
break;
default:
break;
}
return ret;
}
static struct devfreq_governor devfreq_passive = {
.name = DEVFREQ_GOV_PASSIVE,
.flags = DEVFREQ_GOV_FLAG_IMMUTABLE,
.get_target_freq = devfreq_passive_get_target_freq,
.event_handler = devfreq_passive_event_handler,
};
static int __init devfreq_passive_init(void)
{
return devfreq_add_governor(&devfreq_passive);
}
subsys_initcall(devfreq_passive_init);
static void __exit devfreq_passive_exit(void)
{
int ret;
ret = devfreq_remove_governor(&devfreq_passive);
if (ret)
pr_err("%s: failed remove governor %d\n", __func__, ret);
}
module_exit(devfreq_passive_exit);
MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
MODULE_DESCRIPTION("DEVFREQ Passive governor");
MODULE_LICENSE("GPL v2");
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