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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * linux/drivers/devfreq/governor_userspace.c4 *5 * Copyright (C) 2011 Samsung Electronics6 * MyungJoo Ham <myungjoo.ham@samsung.com>7 */8 9#include <linux/slab.h>10#include <linux/device.h>11#include <linux/devfreq.h>12#include <linux/pm.h>13#include <linux/mutex.h>14#include <linux/module.h>15#include "governor.h"16 17struct userspace_data {18 unsigned long user_frequency;19 bool valid;20};21 22static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)23{24 struct userspace_data *data = df->governor_data;25 26 if (data->valid)27 *freq = data->user_frequency;28 else29 *freq = df->previous_freq; /* No user freq specified yet */30 31 return 0;32}33 34static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,35 const char *buf, size_t count)36{37 struct devfreq *devfreq = to_devfreq(dev);38 struct userspace_data *data;39 unsigned long wanted;40 int err = 0;41 42 mutex_lock(&devfreq->lock);43 data = devfreq->governor_data;44 45 sscanf(buf, "%lu", &wanted);46 data->user_frequency = wanted;47 data->valid = true;48 err = update_devfreq(devfreq);49 if (err == 0)50 err = count;51 mutex_unlock(&devfreq->lock);52 return err;53}54 55static ssize_t set_freq_show(struct device *dev,56 struct device_attribute *attr, char *buf)57{58 struct devfreq *devfreq = to_devfreq(dev);59 struct userspace_data *data;60 int err = 0;61 62 mutex_lock(&devfreq->lock);63 data = devfreq->governor_data;64 65 if (data->valid)66 err = sprintf(buf, "%lu\n", data->user_frequency);67 else68 err = sprintf(buf, "undefined\n");69 mutex_unlock(&devfreq->lock);70 return err;71}72 73static DEVICE_ATTR_RW(set_freq);74static struct attribute *dev_entries[] = {75 &dev_attr_set_freq.attr,76 NULL,77};78static const struct attribute_group dev_attr_group = {79 .name = DEVFREQ_GOV_USERSPACE,80 .attrs = dev_entries,81};82 83static int userspace_init(struct devfreq *devfreq)84{85 int err = 0;86 struct userspace_data *data = kzalloc(sizeof(struct userspace_data),87 GFP_KERNEL);88 89 if (!data) {90 err = -ENOMEM;91 goto out;92 }93 data->valid = false;94 devfreq->governor_data = data;95 96 err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);97out:98 return err;99}100 101static void userspace_exit(struct devfreq *devfreq)102{103 /*104 * Remove the sysfs entry, unless this is being called after105 * device_del(), which should have done this already via kobject_del().106 */107 if (devfreq->dev.kobj.sd)108 sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);109 110 kfree(devfreq->governor_data);111 devfreq->governor_data = NULL;112}113 114static int devfreq_userspace_handler(struct devfreq *devfreq,115 unsigned int event, void *data)116{117 int ret = 0;118 119 switch (event) {120 case DEVFREQ_GOV_START:121 ret = userspace_init(devfreq);122 break;123 case DEVFREQ_GOV_STOP:124 userspace_exit(devfreq);125 break;126 default:127 break;128 }129 130 return ret;131}132 133static struct devfreq_governor devfreq_userspace = {134 .name = DEVFREQ_GOV_USERSPACE,135 .get_target_freq = devfreq_userspace_func,136 .event_handler = devfreq_userspace_handler,137};138 139static int __init devfreq_userspace_init(void)140{141 return devfreq_add_governor(&devfreq_userspace);142}143subsys_initcall(devfreq_userspace_init);144 145static void __exit devfreq_userspace_exit(void)146{147 int ret;148 149 ret = devfreq_remove_governor(&devfreq_userspace);150 if (ret)151 pr_err("%s: failed remove governor %d\n", __func__, ret);152 153 return;154}155module_exit(devfreq_userspace_exit);156MODULE_DESCRIPTION("DEVFREQ Userspace governor");157MODULE_LICENSE("GPL");158