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include/linux/cpu_pm.h 2.78 KB
ab10023e0   Colin Cross   cpu_pm: Add cpu p...
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  /*
   * Copyright (C) 2011 Google, Inc.
   *
   * Author:
   *	Colin Cross <ccross@android.com>
   *
   * This software is licensed under the terms of the GNU General Public
   * License version 2, as published by the Free Software Foundation, and
   * may be copied, distributed, and modified under those terms.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   */
  
  #ifndef _LINUX_CPU_PM_H
  #define _LINUX_CPU_PM_H
  
  #include <linux/kernel.h>
  #include <linux/notifier.h>
  
  /*
   * When a CPU goes to a low power state that turns off power to the CPU's
   * power domain, the contents of some blocks (floating point coprocessors,
   * interrupt controllers, caches, timers) in the same power domain can
   * be lost.  The cpm_pm notifiers provide a method for platform idle, suspend,
   * and hotplug implementations to notify the drivers for these blocks that
   * they may be reset.
   *
   * All cpu_pm notifications must be called with interrupts disabled.
   *
   * The notifications are split into two classes: CPU notifications and CPU
   * cluster notifications.
   *
   * CPU notifications apply to a single CPU and must be called on the affected
   * CPU.  They are used to save per-cpu context for affected blocks.
   *
   * CPU cluster notifications apply to all CPUs in a single power domain. They
   * are used to save any global context for affected blocks, and must be called
   * after all the CPUs in the power domain have been notified of the low power
   * state.
   */
  
  /*
   * Event codes passed as unsigned long val to notifier calls
   */
  enum cpu_pm_event {
  	/* A single cpu is entering a low power state */
  	CPU_PM_ENTER,
  
  	/* A single cpu failed to enter a low power state */
  	CPU_PM_ENTER_FAILED,
  
  	/* A single cpu is exiting a low power state */
  	CPU_PM_EXIT,
  
  	/* A cpu power domain is entering a low power state */
  	CPU_CLUSTER_PM_ENTER,
  
  	/* A cpu power domain failed to enter a low power state */
  	CPU_CLUSTER_PM_ENTER_FAILED,
  
  	/* A cpu power domain is exiting a low power state */
  	CPU_CLUSTER_PM_EXIT,
  };
  
  #ifdef CONFIG_CPU_PM
  int cpu_pm_register_notifier(struct notifier_block *nb);
  int cpu_pm_unregister_notifier(struct notifier_block *nb);
  int cpu_pm_enter(void);
  int cpu_pm_exit(void);
  int cpu_cluster_pm_enter(void);
  int cpu_cluster_pm_exit(void);
  
  #else
  
  static inline int cpu_pm_register_notifier(struct notifier_block *nb)
  {
  	return 0;
  }
  
  static inline int cpu_pm_unregister_notifier(struct notifier_block *nb)
  {
  	return 0;
  }
  
  static inline int cpu_pm_enter(void)
  {
  	return 0;
  }
  
  static inline int cpu_pm_exit(void)
  {
  	return 0;
  }
  
  static inline int cpu_cluster_pm_enter(void)
  {
  	return 0;
  }
  
  static inline int cpu_cluster_pm_exit(void)
  {
  	return 0;
  }
  #endif
  #endif