drivers/devfreq/governor_powersave.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/drivers/devfreq/governor_powersave.c
   4  *
   5  *  Copyright (C) 2011 Samsung Electronics
   6  *      MyungJoo Ham <myungjoo.ham@samsung.com>
   7  */
   8
   9 #include <linux/devfreq.h>
  10 #include <linux/module.h>
  11 #include "governor.h"
  12
  13 static int devfreq_powersave_func(struct devfreq *df,
  14                                   unsigned long *freq)
  15 {
  16         /*
  17          * target callback should be able to get ceiling value as
  18          * said in devfreq.h
  19          */
  20         *freq = DEVFREQ_MIN_FREQ;
  21         return 0;
  22 }
  23
  24 static int devfreq_powersave_handler(struct devfreq *devfreq,
  25                                 unsigned int event, void *data)
  26 {
  27         int ret = 0;
  28
  29         if (event == DEVFREQ_GOV_START) {
  30                 mutex_lock(&devfreq->lock);
  31                 ret = update_devfreq(devfreq);
  32                 mutex_unlock(&devfreq->lock);
  33         }
  34
  35         return ret;
  36 }
  37
  38 static struct devfreq_governor devfreq_powersave = {
  39         .name = DEVFREQ_GOV_POWERSAVE,
  40         .get_target_freq = devfreq_powersave_func,
  41         .event_handler = devfreq_powersave_handler,
  42 };
  43
  44 static int __init devfreq_powersave_init(void)
  45 {
  46         return devfreq_add_governor(&devfreq_powersave);
  47 }
  48 subsys_initcall(devfreq_powersave_init);
  49
  50 static void __exit devfreq_powersave_exit(void)
  51 {
  52         int ret;
  53
  54         ret = devfreq_remove_governor(&devfreq_powersave);
  55         if (ret)
  56                 pr_err("%s: failed remove governor %d\n", __func__, ret);
  57
  58         return;
  59 }
  60 module_exit(devfreq_powersave_exit);
  61 MODULE_LICENSE("GPL");