drivers/cpuquiet/governor.c

   1 /*
   2  * Copyright (c) 2012 NVIDIA CORPORATION.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  16  *
  17  */
  18
  19 #include <linux/mutex.h>
  20 #include <linux/module.h>
  21 #include <linux/cpuquiet.h>
  22
  23 #include "cpuquiet.h"
  24
  25 LIST_HEAD(cpuquiet_governors);
  26 struct cpuquiet_governor *cpuquiet_curr_governor;
  27
  28 struct cpuquiet_governor *cpuquiet_get_first_governor(void)
  29 {
  30         if (!list_empty(&cpuquiet_governors))
  31                 return list_entry(cpuquiet_governors.next,
  32                                         struct cpuquiet_governor,
  33                                         governor_list);
  34         else
  35                 return NULL;
  36 }
  37
  38 struct cpuquiet_governor *cpuquiet_find_governor(const char *str)
  39 {
  40         struct cpuquiet_governor *gov;
  41
  42         list_for_each_entry(gov, &cpuquiet_governors, governor_list)
  43                 if (!strnicmp(str, gov->name, CPUQUIET_NAME_LEN))
  44                         return gov;
  45
  46         return NULL;
  47 }
  48
  49 int cpuquiet_switch_governor(struct cpuquiet_governor *gov)
  50 {
  51         int err = 0;
  52
  53         if (cpuquiet_curr_governor) {
  54                 if (cpuquiet_curr_governor->stop)
  55                         cpuquiet_curr_governor->stop();
  56                 module_put(cpuquiet_curr_governor->owner);
  57         }
  58
  59         cpuquiet_curr_governor = gov;
  60
  61         if (gov) {
  62                 if (!try_module_get(cpuquiet_curr_governor->owner))
  63                         return -EINVAL;
  64                 if (gov->start)
  65                         err = gov->start();
  66                 if (!err)
  67                         cpuquiet_curr_governor = gov;
  68         }
  69
  70         return err;
  71 }
  72
  73 int cpuquiet_register_governor(struct cpuquiet_governor *gov)
  74 {
  75         int ret = -EEXIST;
  76
  77         if (!gov)
  78                 return -EINVAL;
  79
  80         mutex_lock(&cpuquiet_lock);
  81         if (cpuquiet_find_governor(gov->name) == NULL) {
  82                 ret = 0;
  83                 list_add_tail(&gov->governor_list, &cpuquiet_governors);
  84                 if (!cpuquiet_curr_governor && cpuquiet_get_driver())
  85                         cpuquiet_switch_governor(gov);
  86         }
  87         mutex_unlock(&cpuquiet_lock);
  88
  89         return ret;
  90 }
  91
  92 void cpuquiet_unregister_governor(struct cpuquiet_governor *gov)
  93 {
  94         if (!gov)
  95                 return;
  96
  97         mutex_lock(&cpuquiet_lock);
  98         if (cpuquiet_curr_governor == gov)
  99                 cpuquiet_switch_governor(NULL);
 100         list_del(&gov->governor_list);
 101         mutex_unlock(&cpuquiet_lock);
 102 }
 103
 104 void cpuquiet_device_busy(void)
 105 {
 106         if (cpuquiet_curr_governor &&
 107                         cpuquiet_curr_governor->device_busy_notification)
 108                 cpuquiet_curr_governor->device_busy_notification();
 109 }
 110
 111 void cpuquiet_device_free(void)
 112 {
 113         if (cpuquiet_curr_governor &&
 114                         cpuquiet_curr_governor->device_free_notification)
 115                 cpuquiet_curr_governor->device_free_notification();
 116 }