drivers/devfreq/governor_powersave.c

   1 /*
   2  *  linux/drivers/devfreq/governor_powersave.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/devfreq.h>
  13 #include <linux/module.h>
  14 #include "governor.h"
  15
  16 static int devfreq_powersave_func(struct devfreq *df,
  17                                   unsigned long *freq)
  18 {
  19         /*
  20          * target callback should be able to get ceiling value as
  21          * said in devfreq.h
  22          */
  23         *freq = df->min_freq;
  24         return 0;
  25 }
  26
  27 static int devfreq_powersave_handler(struct devfreq *devfreq,
  28                                 unsigned int event, void *data)
  29 {
  30         int ret = 0;
  31
  32         if (event == DEVFREQ_GOV_START) {
  33                 mutex_lock(&devfreq->lock);
  34                 ret = update_devfreq(devfreq);
  35                 mutex_unlock(&devfreq->lock);
  36         }
  37
  38         return ret;
  39 }
  40
  41 static struct devfreq_governor devfreq_powersave = {
  42         .name = DEVFREQ_GOV_POWERSAVE,
  43         .get_target_freq = devfreq_powersave_func,
  44         .event_handler = devfreq_powersave_handler,
  45 };
  46
  47 static int __init devfreq_powersave_init(void)
  48 {
  49         return devfreq_add_governor(&devfreq_powersave);
  50 }
  51 subsys_initcall(devfreq_powersave_init);
  52
  53 static void __exit devfreq_powersave_exit(void)
  54 {
  55         int ret;
  56
  57         ret = devfreq_remove_governor(&devfreq_powersave);
  58         if (ret)
  59                 pr_err("%s: failed remove governor %d\n", __func__, ret);
  60
  61         return;
  62 }
  63 module_exit(devfreq_powersave_exit);
  64 MODULE_LICENSE("GPL");