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 #include <linux/kernel.h>
10 #include <linux/cpu_pm.h>
11 #include <linux/module.h>
12 #include <linux/notifier.h>
13 #include <linux/spinlock.h>
14 #include <linux/syscore_ops.h>
15
16 static ATOMIC_NOTIFIER_HEAD(cpu_pm_notifier_chain);
17
18 static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls)
19 {
20 int ret;
21
22 /*
23 * __atomic_notifier_call_chain has a RCU read critical section, which
24 * could be disfunctional in cpu idle. Copy RCU_NONIDLE code to let
25 * RCU know this.
26 */
27 rcu_irq_enter_irqson();
28 ret = __atomic_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL,
29 nr_to_call, nr_calls);
30 rcu_irq_exit_irqson();
31
32 return notifier_to_errno(ret);
33 }
34
35 /**
36 * cpu_pm_register_notifier - register a driver with cpu_pm
37 * @nb: notifier block to register
38 *
39 * Add a driver to a list of drivers that are notified about
40 * CPU and CPU cluster low power entry and exit.
41 *
42 * This function may sleep, and has the same return conditions as
43 * raw_notifier_chain_register.
44 */
45 int cpu_pm_register_notifier(struct notifier_block *nb)
46 {
47 return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb);
48 }
49 EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
50
51 /**
52 * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
53 * @nb: notifier block to be unregistered
54 *
55 * Remove a driver from the CPU PM notifier list.
56 *
57 * This function may sleep, and has the same return conditions as
58 * raw_notifier_chain_unregister.
59 */
60 int cpu_pm_unregister_notifier(struct notifier_block *nb)
61 {
62 return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
63 }
64 EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
65
66 /**
67 * cpu_pm_enter - CPU low power entry notifier
68 *
69 * Notifies listeners that a single CPU is entering a low power state that may
70 * cause some blocks in the same power domain as the cpu to reset.
71 *
72 * Must be called on the affected CPU with interrupts disabled. Platform is
73 * responsible for ensuring that cpu_pm_enter is not called twice on the same
74 * CPU before cpu_pm_exit is called. Notified drivers can include VFP
75 * co-processor, interrupt controller and its PM extensions, local CPU
76 * timers context save/restore which shouldn't be interrupted. Hence it
77 * must be called with interrupts disabled.
78 *
79 * Return conditions are same as __raw_notifier_call_chain.
80 */
81 int cpu_pm_enter(void)
82 {
83 int nr_calls;
84 int ret = 0;
85
86 ret = cpu_pm_notify(CPU_PM_ENTER, -1, &nr_calls);
87 if (ret)
88 /*
89 * Inform listeners (nr_calls - 1) about failure of CPU PM
90 * PM entry who are notified earlier to prepare for it.
91 */
92 cpu_pm_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
93
94 return ret;
95 }
96 EXPORT_SYMBOL_GPL(cpu_pm_enter);
97
98 /**
99 * cpu_pm_exit - CPU low power exit notifier
100 *
101 * Notifies listeners that a single CPU is exiting a low power state that may
102 * have caused some blocks in the same power domain as the cpu to reset.
103 *
104 * Notified drivers can include VFP co-processor, interrupt controller
105 * and its PM extensions, local CPU timers context save/restore which
106 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
107 *
108 * Return conditions are same as __raw_notifier_call_chain.
109 */
110 int cpu_pm_exit(void)
111 {
112 return cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
113 }
114 EXPORT_SYMBOL_GPL(cpu_pm_exit);
115
116 /**
117 * cpu_cluster_pm_enter - CPU cluster low power entry notifier
118 *
119 * Notifies listeners that all cpus in a power domain are entering a low power
120 * state that may cause some blocks in the same power domain to reset.
121 *
122 * Must be called after cpu_pm_enter has been called on all cpus in the power
123 * domain, and before cpu_pm_exit has been called on any cpu in the power
124 * domain. Notified drivers can include VFP co-processor, interrupt controller
125 * and its PM extensions, local CPU timers context save/restore which
126 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
127 *
128 * Must be called with interrupts disabled.
129 *
130 * Return conditions are same as __raw_notifier_call_chain.
131 */
132 int cpu_cluster_pm_enter(void)
133 {
134 int nr_calls;
135 int ret = 0;
136
137 ret = cpu_pm_notify(CPU_CLUSTER_PM_ENTER, -1, &nr_calls);
138 if (ret)
139 /*
140 * Inform listeners (nr_calls - 1) about failure of CPU cluster
141 * PM entry who are notified earlier to prepare for it.
142 */
143 cpu_pm_notify(CPU_CLUSTER_PM_ENTER_FAILED, nr_calls - 1, NULL);
144
145 return ret;
146 }
147 EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
148
149 /**
150 * cpu_cluster_pm_exit - CPU cluster low power exit notifier
151 *
152 * Notifies listeners that all cpus in a power domain are exiting form a
153 * low power state that may have caused some blocks in the same power domain
154 * to reset.
155 *
156 * Must be called after cpu_cluster_pm_enter has been called for the power
157 * domain, and before cpu_pm_exit has been called on any cpu in the power
158 * domain. Notified drivers can include VFP co-processor, interrupt controller
159 * and its PM extensions, local CPU timers context save/restore which
160 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
161 *
162 * Return conditions are same as __raw_notifier_call_chain.
163 */
164 int cpu_cluster_pm_exit(void)
165 {
166 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
167 }
168 EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
169
170 #ifdef CONFIG_PM
171 static int cpu_pm_suspend(void)
172 {
173 int ret;
174
175 ret = cpu_pm_enter();
176 if (ret)
177 return ret;
178
179 ret = cpu_cluster_pm_enter();
180 return ret;
181 }
182
183 static void cpu_pm_resume(void)
184 {
185 cpu_cluster_pm_exit();
186 cpu_pm_exit();
187 }
188
189 static struct syscore_ops cpu_pm_syscore_ops = {
190 .suspend = cpu_pm_suspend,
191 .resume = cpu_pm_resume,
192 };
193
194 static int cpu_pm_init(void)
195 {
196 register_syscore_ops(&cpu_pm_syscore_ops);
197 return 0;
198 }
199 core_initcall(cpu_pm_init);
200 #endif