drivers/devfreq/governor_userspace.c

   1 /*
   2  *  linux/drivers/devfreq/governor_simpleondemand.c
   3  *
   4  *  Copyright (C) 2011 Samsung Electronics
   5  *      MyungJoo Ham <myungjoo.ham@samsung.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/device.h>
  14 #include <linux/devfreq.h>
  15 #include <linux/pm.h>
  16 #include <linux/mutex.h>
  17 #include <linux/module.h>
  18 #include "governor.h"
  19
  20 struct userspace_data {
  21         unsigned long user_frequency;
  22         bool valid;
  23 };
  24
  25 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
  26 {
  27         struct userspace_data *data = df->data;
  28
  29         if (data->valid) {
  30                 unsigned long adjusted_freq = data->user_frequency;
  31
  32                 if (df->max_freq && adjusted_freq > df->max_freq)
  33                         adjusted_freq = df->max_freq;
  34
  35                 if (df->min_freq && adjusted_freq < df->min_freq)
  36                         adjusted_freq = df->min_freq;
  37
  38                 *freq = adjusted_freq;
  39         } else {
  40                 *freq = df->previous_freq; /* No user freq specified yet */
  41         }
  42         return 0;
  43 }
  44
  45 static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
  46                           const char *buf, size_t count)
  47 {
  48         struct devfreq *devfreq = to_devfreq(dev);
  49         struct userspace_data *data;
  50         unsigned long wanted;
  51         int err = 0;
  52
  53
  54         mutex_lock(&devfreq->lock);
  55         data = devfreq->data;
  56
  57         sscanf(buf, "%lu", &wanted);
  58         data->user_frequency = wanted;
  59         data->valid = true;
  60         err = update_devfreq(devfreq);
  61         if (err == 0)
  62                 err = count;
  63         mutex_unlock(&devfreq->lock);
  64         return err;
  65 }
  66
  67 static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
  68                          char *buf)
  69 {
  70         struct devfreq *devfreq = to_devfreq(dev);
  71         struct userspace_data *data;
  72         int err = 0;
  73
  74         mutex_lock(&devfreq->lock);
  75         data = devfreq->data;
  76
  77         if (data->valid)
  78                 err = sprintf(buf, "%lu\n", data->user_frequency);
  79         else
  80                 err = sprintf(buf, "undefined\n");
  81         mutex_unlock(&devfreq->lock);
  82         return err;
  83 }
  84
  85 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
  86 static struct attribute *dev_entries[] = {
  87         &dev_attr_set_freq.attr,
  88         NULL,
  89 };
  90 static struct attribute_group dev_attr_group = {
  91         .name   = "userspace",
  92         .attrs  = dev_entries,
  93 };
  94
  95 static int userspace_init(struct devfreq *devfreq)
  96 {
  97         int err = 0;
  98         struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
  99                                               GFP_KERNEL);
 100
 101         if (!data) {
 102                 err = -ENOMEM;
 103                 goto out;
 104         }
 105         data->valid = false;
 106         devfreq->data = data;
 107
 108         err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
 109 out:
 110         return err;
 111 }
 112
 113 static void userspace_exit(struct devfreq *devfreq)
 114 {
 115         sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
 116         kfree(devfreq->data);
 117         devfreq->data = NULL;
 118 }
 119
 120 static int devfreq_userspace_handler(struct devfreq *devfreq,
 121                         unsigned int event, void *data)
 122 {
 123         int ret = 0;
 124
 125         switch (event) {
 126         case DEVFREQ_GOV_START:
 127                 ret = userspace_init(devfreq);
 128                 break;
 129         case DEVFREQ_GOV_STOP:
 130                 userspace_exit(devfreq);
 131                 break;
 132         default:
 133                 break;
 134         }
 135
 136         return ret;
 137 }
 138
 139 static struct devfreq_governor devfreq_userspace = {
 140         .name = "userspace",
 141         .get_target_freq = devfreq_userspace_func,
 142         .event_handler = devfreq_userspace_handler,
 143 };
 144
 145 static int __init devfreq_userspace_init(void)
 146 {
 147         return devfreq_add_governor(&devfreq_userspace);
 148 }
 149 subsys_initcall(devfreq_userspace_init);
 150
 151 static void __exit devfreq_userspace_exit(void)
 152 {
 153         int ret;
 154
 155         ret = devfreq_remove_governor(&devfreq_userspace);
 156         if (ret)
 157                 pr_err("%s: failed remove governor %d\n", __func__, ret);
 158
 159         return;
 160 }
 161 module_exit(devfreq_userspace_exit);
 162 MODULE_LICENSE("GPL");