include/linux/cpu_pm.h

   1 /*
   2  * Copyright (C) 2011 Google, Inc.
   3  *
   4  * Author:
   5  *      Colin Cross <ccross@android.com>
   6  *
   7  * This software is licensed under the terms of the GNU General Public
   8  * License version 2, as published by the Free Software Foundation, and
   9  * may be copied, distributed, and modified under those terms.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  */
  17
  18 #ifndef _LINUX_CPU_PM_H
  19 #define _LINUX_CPU_PM_H
  20
  21 #include <linux/kernel.h>
  22 #include <linux/notifier.h>
  23
  24 /*
  25  * When a CPU goes to a low power state that turns off power to the CPU's
  26  * power domain, the contents of some blocks (floating point coprocessors,
  27  * interrupt controllers, caches, timers) in the same power domain can
  28  * be lost.  The cpm_pm notifiers provide a method for platform idle, suspend,
  29  * and hotplug implementations to notify the drivers for these blocks that
  30  * they may be reset.
  31  *
  32  * All cpu_pm notifications must be called with interrupts disabled.
  33  *
  34  * The notifications are split into two classes: CPU notifications and CPU
  35  * cluster notifications.
  36  *
  37  * CPU notifications apply to a single CPU and must be called on the affected
  38  * CPU.  They are used to save per-cpu context for affected blocks.
  39  *
  40  * CPU cluster notifications apply to all CPUs in a single power domain. They
  41  * are used to save any global context for affected blocks, and must be called
  42  * after all the CPUs in the power domain have been notified of the low power
  43  * state.
  44  */
  45
  46 /*
  47  * Event codes passed as unsigned long val to notifier calls
  48  */
  49 enum cpu_pm_event {
  50         /* A single cpu is entering a low power state */
  51         CPU_PM_ENTER,
  52
  53         /* A single cpu failed to enter a low power state */
  54         CPU_PM_ENTER_FAILED,
  55
  56         /* A single cpu is exiting a low power state */
  57         CPU_PM_EXIT,
  58
  59         /* A cpu power domain is entering a low power state */
  60         CPU_CLUSTER_PM_ENTER,
  61
  62         /* A cpu power domain failed to enter a low power state */
  63         CPU_CLUSTER_PM_ENTER_FAILED,
  64
  65         /* A cpu power domain is exiting a low power state */
  66         CPU_CLUSTER_PM_EXIT,
  67 };
  68
  69 #ifdef CONFIG_CPU_PM
  70 int cpu_pm_register_notifier(struct notifier_block *nb);
  71 int cpu_pm_unregister_notifier(struct notifier_block *nb);
  72 int cpu_pm_enter(void);
  73 int cpu_pm_exit(void);
  74 int cpu_cluster_pm_enter(void);
  75 int cpu_cluster_pm_exit(void);
  76
  77 #else
  78
  79 static inline int cpu_pm_register_notifier(struct notifier_block *nb)
  80 {
  81         return 0;
  82 }
  83
  84 static inline int cpu_pm_unregister_notifier(struct notifier_block *nb)
  85 {
  86         return 0;
  87 }
  88
  89 static inline int cpu_pm_enter(void)
  90 {
  91         return 0;
  92 }
  93
  94 static inline int cpu_pm_exit(void)
  95 {
  96         return 0;
  97 }
  98
  99 static inline int cpu_cluster_pm_enter(void)
 100 {
 101         return 0;
 102 }
 103
 104 static inline int cpu_cluster_pm_exit(void)
 105 {
 106         return 0;
 107 }
 108 #endif
 109 #endif