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5fdded8448
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>
156 lines
3.3 KiB
C
156 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/drivers/devfreq/governor_userspace.c
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*
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* Copyright (C) 2011 Samsung Electronics
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* MyungJoo Ham <myungjoo.ham@samsung.com>
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*/
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#include <linux/slab.h>
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#include <linux/device.h>
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#include <linux/devfreq.h>
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#include <linux/pm.h>
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#include <linux/mutex.h>
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#include <linux/module.h>
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#include "governor.h"
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struct userspace_data {
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unsigned long user_frequency;
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bool valid;
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};
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static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
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{
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struct userspace_data *data = df->governor_data;
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if (data->valid)
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*freq = data->user_frequency;
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else
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*freq = df->previous_freq; /* No user freq specified yet */
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return 0;
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}
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static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct devfreq *devfreq = to_devfreq(dev);
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struct userspace_data *data;
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unsigned long wanted;
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int err = 0;
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mutex_lock(&devfreq->lock);
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data = devfreq->governor_data;
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sscanf(buf, "%lu", &wanted);
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data->user_frequency = wanted;
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data->valid = true;
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err = update_devfreq(devfreq);
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if (err == 0)
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err = count;
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mutex_unlock(&devfreq->lock);
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return err;
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}
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static ssize_t set_freq_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct devfreq *devfreq = to_devfreq(dev);
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struct userspace_data *data;
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int err = 0;
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mutex_lock(&devfreq->lock);
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data = devfreq->governor_data;
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if (data->valid)
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err = sprintf(buf, "%lu\n", data->user_frequency);
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else
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err = sprintf(buf, "undefined\n");
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mutex_unlock(&devfreq->lock);
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return err;
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}
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static DEVICE_ATTR_RW(set_freq);
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static struct attribute *dev_entries[] = {
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&dev_attr_set_freq.attr,
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NULL,
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};
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static const struct attribute_group dev_attr_group = {
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.name = DEVFREQ_GOV_USERSPACE,
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.attrs = dev_entries,
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};
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static int userspace_init(struct devfreq *devfreq)
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{
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int err = 0;
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struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
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GFP_KERNEL);
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if (!data) {
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err = -ENOMEM;
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goto out;
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}
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data->valid = false;
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devfreq->governor_data = data;
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err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
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out:
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return err;
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}
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static void userspace_exit(struct devfreq *devfreq)
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{
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/*
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* Remove the sysfs entry, unless this is being called after
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* device_del(), which should have done this already via kobject_del().
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*/
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if (devfreq->dev.kobj.sd)
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sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
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kfree(devfreq->governor_data);
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devfreq->governor_data = NULL;
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}
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static int devfreq_userspace_handler(struct devfreq *devfreq,
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unsigned int event, void *data)
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{
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int ret = 0;
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switch (event) {
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case DEVFREQ_GOV_START:
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ret = userspace_init(devfreq);
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break;
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case DEVFREQ_GOV_STOP:
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userspace_exit(devfreq);
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break;
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default:
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break;
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}
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return ret;
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}
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static struct devfreq_governor devfreq_userspace = {
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.name = DEVFREQ_GOV_USERSPACE,
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.get_target_freq = devfreq_userspace_func,
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.event_handler = devfreq_userspace_handler,
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};
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static int __init devfreq_userspace_init(void)
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{
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return devfreq_add_governor(&devfreq_userspace);
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}
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subsys_initcall(devfreq_userspace_init);
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static void __exit devfreq_userspace_exit(void)
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{
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int ret;
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ret = devfreq_remove_governor(&devfreq_userspace);
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if (ret)
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pr_err("%s: failed remove governor %d\n", __func__, ret);
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return;
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}
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module_exit(devfreq_userspace_exit);
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MODULE_LICENSE("GPL");
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