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