cpu_pm.h

  1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * Copyright (C) 2011 Google, Inc.
  4 *
  5 * Author:
  6 *	Colin Cross <ccross@android.com>
  7 */
  8
  9#ifndef _LINUX_CPU_PM_H
 10#define _LINUX_CPU_PM_H
 11
 12#include <linux/kernel.h>
 13#include <linux/notifier.h>
 14
 15/*
 16 * When a CPU goes to a low power state that turns off power to the CPU's
 17 * power domain, the contents of some blocks (floating point coprocessors,
 18 * interrupt controllers, caches, timers) in the same power domain can
 19 * be lost.  The cpm_pm notifiers provide a method for platform idle, suspend,
 20 * and hotplug implementations to notify the drivers for these blocks that
 21 * they may be reset.
 22 *
 23 * All cpu_pm notifications must be called with interrupts disabled.
 24 *
 25 * The notifications are split into two classes: CPU notifications and CPU
 26 * cluster notifications.
 27 *
 28 * CPU notifications apply to a single CPU and must be called on the affected
 29 * CPU.  They are used to save per-cpu context for affected blocks.
 30 *
 31 * CPU cluster notifications apply to all CPUs in a single power domain. They
 32 * are used to save any global context for affected blocks, and must be called
 33 * after all the CPUs in the power domain have been notified of the low power
 34 * state.
 35 */
 36
 37/*
 38 * Event codes passed as unsigned long val to notifier calls
 39 */
 40enum cpu_pm_event {
 41	/* A single cpu is entering a low power state */
 42	CPU_PM_ENTER,
 43
 44	/* A single cpu failed to enter a low power state */
 45	CPU_PM_ENTER_FAILED,
 46
 47	/* A single cpu is exiting a low power state */
 48	CPU_PM_EXIT,
 49
 50	/* A cpu power domain is entering a low power state */
 51	CPU_CLUSTER_PM_ENTER,
 52
 53	/* A cpu power domain failed to enter a low power state */
 54	CPU_CLUSTER_PM_ENTER_FAILED,
 55
 56	/* A cpu power domain is exiting a low power state */
 57	CPU_CLUSTER_PM_EXIT,
 58};
 59
 60#ifdef CONFIG_CPU_PM
 61int cpu_pm_register_notifier(struct notifier_block *nb);
 62int cpu_pm_unregister_notifier(struct notifier_block *nb);
 63int cpu_pm_enter(void);
 64int cpu_pm_exit(void);
 65int cpu_cluster_pm_enter(void);
 66int cpu_cluster_pm_exit(void);
 67
 68#else
 69
 70static inline int cpu_pm_register_notifier(struct notifier_block *nb)
 71{
 72	return 0;
 73}
 74
 75static inline int cpu_pm_unregister_notifier(struct notifier_block *nb)
 76{
 77	return 0;
 78}
 79
 80static inline int cpu_pm_enter(void)
 81{
 82	return 0;
 83}
 84
 85static inline int cpu_pm_exit(void)
 86{
 87	return 0;
 88}
 89
 90static inline int cpu_cluster_pm_enter(void)
 91{
 92	return 0;
 93}
 94
 95static inline int cpu_cluster_pm_exit(void)
 96{
 97	return 0;
 98}
 99#endif
100#endif