linux/drivers/devfreq/governor_userspace.c
Kant Fan 5fdded8448 PM/devfreq: governor: Add a private governor_data for governor
The member void *data in the structure devfreq can be overwrite
by governor_userspace. For example:
1. The device driver assigned the devfreq governor to simple_ondemand
by the function devfreq_add_device() and init the devfreq member
void *data to a pointer of a static structure devfreq_simple_ondemand_data
by the function devfreq_add_device().
2. The user changed the devfreq governor to userspace by the command
"echo userspace > /sys/class/devfreq/.../governor".
3. The governor userspace alloced a dynamic memory for the struct
userspace_data and assigend the member void *data of devfreq to
this memory by the function userspace_init().
4. The user changed the devfreq governor back to simple_ondemand
by the command "echo simple_ondemand > /sys/class/devfreq/.../governor".
5. The governor userspace exited and assigned the member void *data
in the structure devfreq to NULL by the function userspace_exit().
6. The governor simple_ondemand fetched the static information of
devfreq_simple_ondemand_data in the function
devfreq_simple_ondemand_func() but the member void *data of devfreq was
assigned to NULL by the function userspace_exit().
7. The information of upthreshold and downdifferential is lost
and the governor simple_ondemand can't work correctly.

The member void *data in the structure devfreq is designed for
a static pointer used in a governor and inited by the function
devfreq_add_device(). This patch add an element named governor_data
in the devfreq structure which can be used by a governor(E.g userspace)
who want to assign a private data to do some private things.

Fixes: ce26c5bb95 ("PM / devfreq: Add basic governors")
Cc: stable@vger.kernel.org # 5.10+
Reviewed-by: Chanwoo Choi <cwchoi00@gmail.com>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kant Fan <kant@allwinnertech.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
2022-11-20 20:49:51 +09:00

157 lines
3.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/drivers/devfreq/governor_userspace.c
*
* Copyright (C) 2011 Samsung Electronics
* MyungJoo Ham <myungjoo.ham@samsung.com>
*/
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/devfreq.h>
#include <linux/pm.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include "governor.h"
struct userspace_data {
unsigned long user_frequency;
bool valid;
};
static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
{
struct userspace_data *data = df->governor_data;
if (data->valid)
*freq = data->user_frequency;
else
*freq = df->previous_freq; /* No user freq specified yet */
return 0;
}
static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
struct devfreq *devfreq = to_devfreq(dev);
struct userspace_data *data;
unsigned long wanted;
int err = 0;
mutex_lock(&devfreq->lock);
data = devfreq->governor_data;
sscanf(buf, "%lu", &wanted);
data->user_frequency = wanted;
data->valid = true;
err = update_devfreq(devfreq);
if (err == 0)
err = count;
mutex_unlock(&devfreq->lock);
return err;
}
static ssize_t set_freq_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct devfreq *devfreq = to_devfreq(dev);
struct userspace_data *data;
int err = 0;
mutex_lock(&devfreq->lock);
data = devfreq->governor_data;
if (data->valid)
err = sprintf(buf, "%lu\n", data->user_frequency);
else
err = sprintf(buf, "undefined\n");
mutex_unlock(&devfreq->lock);
return err;
}
static DEVICE_ATTR_RW(set_freq);
static struct attribute *dev_entries[] = {
&dev_attr_set_freq.attr,
NULL,
};
static const struct attribute_group dev_attr_group = {
.name = DEVFREQ_GOV_USERSPACE,
.attrs = dev_entries,
};
static int userspace_init(struct devfreq *devfreq)
{
int err = 0;
struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
GFP_KERNEL);
if (!data) {
err = -ENOMEM;
goto out;
}
data->valid = false;
devfreq->governor_data = data;
err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
out:
return err;
}
static void userspace_exit(struct devfreq *devfreq)
{
/*
* Remove the sysfs entry, unless this is being called after
* device_del(), which should have done this already via kobject_del().
*/
if (devfreq->dev.kobj.sd)
sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
kfree(devfreq->governor_data);
devfreq->governor_data = NULL;
}
static int devfreq_userspace_handler(struct devfreq *devfreq,
unsigned int event, void *data)
{
int ret = 0;
switch (event) {
case DEVFREQ_GOV_START:
ret = userspace_init(devfreq);
break;
case DEVFREQ_GOV_STOP:
userspace_exit(devfreq);
break;
default:
break;
}
return ret;
}
static struct devfreq_governor devfreq_userspace = {
.name = DEVFREQ_GOV_USERSPACE,
.get_target_freq = devfreq_userspace_func,
.event_handler = devfreq_userspace_handler,
};
static int __init devfreq_userspace_init(void)
{
return devfreq_add_governor(&devfreq_userspace);
}
subsys_initcall(devfreq_userspace_init);
static void __exit devfreq_userspace_exit(void)
{
int ret;
ret = devfreq_remove_governor(&devfreq_userspace);
if (ret)
pr_err("%s: failed remove governor %d\n", __func__, ret);
return;
}
module_exit(devfreq_userspace_exit);
MODULE_LICENSE("GPL");