drivers/devfreq/governor_userspace.c

   1 /*
   2  *  linux/drivers/devfreq/governor_userspace.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         mutex_lock(&devfreq->lock);
  54         data = devfreq->data;
  55
  56         sscanf(buf, "%lu", &wanted);
  57         data->user_frequency = wanted;
  58         data->valid = true;
  59         err = update_devfreq(devfreq);
  60         if (err == 0)
  61                 err = count;
  62         mutex_unlock(&devfreq->lock);
  63         return err;
  64 }
  65
  66 static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
  67                          char *buf)
  68 {
  69         struct devfreq *devfreq = to_devfreq(dev);
  70         struct userspace_data *data;
  71         int err = 0;
  72
  73         mutex_lock(&devfreq->lock);
  74         data = devfreq->data;
  75
  76         if (data->valid)
  77                 err = sprintf(buf, "%lu\n", data->user_frequency);
  78         else
  79                 err = sprintf(buf, "undefined\n");
  80         mutex_unlock(&devfreq->lock);
  81         return err;
  82 }
  83
  84 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
  85 static struct attribute *dev_entries[] = {
  86         &dev_attr_set_freq.attr,
  87         NULL,
  88 };
  89 static struct attribute_group dev_attr_group = {
  90         .name   = "userspace",
  91         .attrs  = dev_entries,
  92 };
  93
  94 static int userspace_init(struct devfreq *devfreq)
  95 {
  96         int err = 0;
  97         struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
  98                                               GFP_KERNEL);
  99
 100         if (!data) {
 101                 err = -ENOMEM;
 102                 goto out;
 103         }
 104         data->valid = false;
 105         devfreq->data = data;
 106
 107         err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
 108 out:
 109         return err;
 110 }
 111
 112 static void userspace_exit(struct devfreq *devfreq)
 113 {
 114         /*
 115          * Remove the sysfs entry, unless this is being called after
 116          * device_del(), which should have done this already via kobject_del().
 117          */
 118         if (devfreq->dev.kobj.sd)
 119                 sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
 120
 121         kfree(devfreq->data);
 122         devfreq->data = NULL;
 123 }
 124
 125 static int devfreq_userspace_handler(struct devfreq *devfreq,
 126                         unsigned int event, void *data)
 127 {
 128         int ret = 0;
 129
 130         switch (event) {
 131         case DEVFREQ_GOV_START:
 132                 ret = userspace_init(devfreq);
 133                 break;
 134         case DEVFREQ_GOV_STOP:
 135                 userspace_exit(devfreq);
 136                 break;
 137         default:
 138                 break;
 139         }
 140
 141         return ret;
 142 }
 143
 144 static struct devfreq_governor devfreq_userspace = {
 145         .name = "userspace",
 146         .get_target_freq = devfreq_userspace_func,
 147         .event_handler = devfreq_userspace_handler,
 148 };
 149
 150 static int __init devfreq_userspace_init(void)
 151 {
 152         return devfreq_add_governor(&devfreq_userspace);
 153 }
 154 subsys_initcall(devfreq_userspace_init);
 155
 156 static void __exit devfreq_userspace_exit(void)
 157 {
 158         int ret;
 159
 160         ret = devfreq_remove_governor(&devfreq_userspace);
 161         if (ret)
 162                 pr_err("%s: failed remove governor %d\n", __func__, ret);
 163
 164         return;
 165 }
 166 module_exit(devfreq_userspace_exit);
 167 MODULE_LICENSE("GPL");