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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/*
17 * atomic_notifiers use a spinlock_t, which can block under PREEMPT_RT.
18 * Notifications for cpu_pm will be issued by the idle task itself, which can
19 * never block, IOW it requires using a raw_spinlock_t.
20 */
21static struct {
22 struct raw_notifier_head chain;
23 raw_spinlock_t lock;
24} cpu_pm_notifier = {
25 .chain = RAW_NOTIFIER_INIT(cpu_pm_notifier.chain),
26 .lock = __RAW_SPIN_LOCK_UNLOCKED(cpu_pm_notifier.lock),
27};
28
29static int cpu_pm_notify(enum cpu_pm_event event)
30{
31 int ret;
32
33 /*
34 * This introduces a RCU read critical section, which could be
35 * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know
36 * this.
37 */
38 ct_irq_enter_irqson();
39 rcu_read_lock();
40 ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
41 rcu_read_unlock();
42 ct_irq_exit_irqson();
43
44 return notifier_to_errno(ret);
45}
46
47static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down)
48{
49 unsigned long flags;
50 int ret;
51
52 ct_irq_enter_irqson();
53 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
54 ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
55 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
56 ct_irq_exit_irqson();
57
58 return notifier_to_errno(ret);
59}
60
61/**
62 * cpu_pm_register_notifier - register a driver with cpu_pm
63 * @nb: notifier block to register
64 *
65 * Add a driver to a list of drivers that are notified about
66 * CPU and CPU cluster low power entry and exit.
67 *
68 * This function has the same return conditions as raw_notifier_chain_register.
69 */
70int cpu_pm_register_notifier(struct notifier_block *nb)
71{
72 unsigned long flags;
73 int ret;
74
75 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
76 ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb);
77 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
78 return ret;
79}
80EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
81
82/**
83 * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
84 * @nb: notifier block to be unregistered
85 *
86 * Remove a driver from the CPU PM notifier list.
87 *
88 * This function has the same return conditions as raw_notifier_chain_unregister.
89 */
90int cpu_pm_unregister_notifier(struct notifier_block *nb)
91{
92 unsigned long flags;
93 int ret;
94
95 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
96 ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb);
97 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
98 return ret;
99}
100EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
101
102/**
103 * cpu_pm_enter - CPU low power entry notifier
104 *
105 * Notifies listeners that a single CPU is entering a low power state that may
106 * cause some blocks in the same power domain as the cpu to reset.
107 *
108 * Must be called on the affected CPU with interrupts disabled. Platform is
109 * responsible for ensuring that cpu_pm_enter is not called twice on the same
110 * CPU before cpu_pm_exit is called. Notified drivers can include VFP
111 * co-processor, interrupt controller and its PM extensions, local CPU
112 * timers context save/restore which shouldn't be interrupted. Hence it
113 * must be called with interrupts disabled.
114 *
115 * Return conditions are same as __raw_notifier_call_chain.
116 */
117int cpu_pm_enter(void)
118{
119 return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
120}
121EXPORT_SYMBOL_GPL(cpu_pm_enter);
122
123/**
124 * cpu_pm_exit - CPU low power exit notifier
125 *
126 * Notifies listeners that a single CPU is exiting a low power state that may
127 * have caused some blocks in the same power domain as the cpu to reset.
128 *
129 * Notified drivers can include VFP co-processor, interrupt controller
130 * and its PM extensions, local CPU timers context save/restore which
131 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
132 *
133 * Return conditions are same as __raw_notifier_call_chain.
134 */
135int cpu_pm_exit(void)
136{
137 return cpu_pm_notify(CPU_PM_EXIT);
138}
139EXPORT_SYMBOL_GPL(cpu_pm_exit);
140
141/**
142 * cpu_cluster_pm_enter - CPU cluster low power entry notifier
143 *
144 * Notifies listeners that all cpus in a power domain are entering a low power
145 * state that may cause some blocks in the same power domain to reset.
146 *
147 * Must be called after cpu_pm_enter has been called on all cpus in the power
148 * domain, and before cpu_pm_exit has been called on any cpu in the power
149 * domain. Notified drivers can include VFP co-processor, interrupt controller
150 * and its PM extensions, local CPU timers context save/restore which
151 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
152 *
153 * Must be called with interrupts disabled.
154 *
155 * Return conditions are same as __raw_notifier_call_chain.
156 */
157int cpu_cluster_pm_enter(void)
158{
159 return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED);
160}
161EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
162
163/**
164 * cpu_cluster_pm_exit - CPU cluster low power exit notifier
165 *
166 * Notifies listeners that all cpus in a power domain are exiting form a
167 * low power state that may have caused some blocks in the same power domain
168 * to reset.
169 *
170 * Must be called after cpu_cluster_pm_enter has been called for the power
171 * domain, and before cpu_pm_exit has been called on any cpu in the power
172 * domain. Notified drivers can include VFP co-processor, interrupt controller
173 * and its PM extensions, local CPU timers context save/restore which
174 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
175 *
176 * Return conditions are same as __raw_notifier_call_chain.
177 */
178int cpu_cluster_pm_exit(void)
179{
180 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT);
181}
182EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
183
184#ifdef CONFIG_PM
185static int cpu_pm_suspend(void)
186{
187 int ret;
188
189 ret = cpu_pm_enter();
190 if (ret)
191 return ret;
192
193 ret = cpu_cluster_pm_enter();
194 return ret;
195}
196
197static void cpu_pm_resume(void)
198{
199 cpu_cluster_pm_exit();
200 cpu_pm_exit();
201}
202
203static struct syscore_ops cpu_pm_syscore_ops = {
204 .suspend = cpu_pm_suspend,
205 .resume = cpu_pm_resume,
206};
207
208static int cpu_pm_init(void)
209{
210 register_syscore_ops(&cpu_pm_syscore_ops);
211 return 0;
212}
213core_initcall(cpu_pm_init);
214#endif
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
16static ATOMIC_NOTIFIER_HEAD(cpu_pm_notifier_chain);
17
18static 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 */
45int cpu_pm_register_notifier(struct notifier_block *nb)
46{
47 return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb);
48}
49EXPORT_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 */
60int cpu_pm_unregister_notifier(struct notifier_block *nb)
61{
62 return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
63}
64EXPORT_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 */
81int 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}
96EXPORT_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 */
110int cpu_pm_exit(void)
111{
112 return cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
113}
114EXPORT_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 */
132int 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}
147EXPORT_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 */
164int cpu_cluster_pm_exit(void)
165{
166 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
167}
168EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
169
170#ifdef CONFIG_PM
171static 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
183static void cpu_pm_resume(void)
184{
185 cpu_cluster_pm_exit();
186 cpu_pm_exit();
187}
188
189static struct syscore_ops cpu_pm_syscore_ops = {
190 .suspend = cpu_pm_suspend,
191 .resume = cpu_pm_resume,
192};
193
194static int cpu_pm_init(void)
195{
196 register_syscore_ops(&cpu_pm_syscore_ops);
197 return 0;
198}
199core_initcall(cpu_pm_init);
200#endif