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  */
40 enum 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
61 int cpu_pm_register_notifier(struct notifier_block *nb);
62 int cpu_pm_unregister_notifier(struct notifier_block *nb);
63 int cpu_pm_enter(void);
64 int cpu_pm_exit(void);
65 int cpu_cluster_pm_enter(void);
66 int cpu_cluster_pm_exit(void);
67 
68 #else
69 
cpu_pm_register_notifier(struct notifier_block * nb)70 static inline int cpu_pm_register_notifier(struct notifier_block *nb)
71 {
72 	return 0;
73 }
74 
cpu_pm_unregister_notifier(struct notifier_block * nb)75 static inline int cpu_pm_unregister_notifier(struct notifier_block *nb)
76 {
77 	return 0;
78 }
79 
cpu_pm_enter(void)80 static inline int cpu_pm_enter(void)
81 {
82 	return 0;
83 }
84 
cpu_pm_exit(void)85 static inline int cpu_pm_exit(void)
86 {
87 	return 0;
88 }
89 
cpu_cluster_pm_enter(void)90 static inline int cpu_cluster_pm_enter(void)
91 {
92 	return 0;
93 }
94 
cpu_cluster_pm_exit(void)95 static inline int cpu_cluster_pm_exit(void)
96 {
97 	return 0;
98 }
99 #endif
100 #endif
101