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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
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
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 rcu_read_lock();
34 ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
35 rcu_read_unlock();
36
37 return notifier_to_errno(ret);
38}
39
40static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down)
41{
42 unsigned long flags;
43 int ret;
44
45 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
46 ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
47 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
48
49 return notifier_to_errno(ret);
50}
51
52/**
53 * cpu_pm_register_notifier - register a driver with cpu_pm
54 * @nb: notifier block to register
55 *
56 * Add a driver to a list of drivers that are notified about
57 * CPU and CPU cluster low power entry and exit.
58 *
59 * This function has the same return conditions as raw_notifier_chain_register.
60 */
61int cpu_pm_register_notifier(struct notifier_block *nb)
62{
63 unsigned long flags;
64 int ret;
65
66 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
67 ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb);
68 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
69 return ret;
70}
71EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
72
73/**
74 * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
75 * @nb: notifier block to be unregistered
76 *
77 * Remove a driver from the CPU PM notifier list.
78 *
79 * This function has the same return conditions as raw_notifier_chain_unregister.
80 */
81int cpu_pm_unregister_notifier(struct notifier_block *nb)
82{
83 unsigned long flags;
84 int ret;
85
86 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
87 ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb);
88 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
89 return ret;
90}
91EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
92
93/**
94 * cpu_pm_enter - CPU low power entry notifier
95 *
96 * Notifies listeners that a single CPU is entering a low power state that may
97 * cause some blocks in the same power domain as the cpu to reset.
98 *
99 * Must be called on the affected CPU with interrupts disabled. Platform is
100 * responsible for ensuring that cpu_pm_enter is not called twice on the same
101 * CPU before cpu_pm_exit is called. Notified drivers can include VFP
102 * co-processor, interrupt controller and its PM extensions, local CPU
103 * timers context save/restore which shouldn't be interrupted. Hence it
104 * must be called with interrupts disabled.
105 *
106 * Return conditions are same as __raw_notifier_call_chain.
107 */
108int cpu_pm_enter(void)
109{
110 return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
111}
112EXPORT_SYMBOL_GPL(cpu_pm_enter);
113
114/**
115 * cpu_pm_exit - CPU low power exit notifier
116 *
117 * Notifies listeners that a single CPU is exiting a low power state that may
118 * have caused some blocks in the same power domain as the cpu to reset.
119 *
120 * Notified drivers can include VFP co-processor, interrupt controller
121 * and its PM extensions, local CPU timers context save/restore which
122 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
123 *
124 * Return conditions are same as __raw_notifier_call_chain.
125 */
126int cpu_pm_exit(void)
127{
128 return cpu_pm_notify(CPU_PM_EXIT);
129}
130EXPORT_SYMBOL_GPL(cpu_pm_exit);
131
132/**
133 * cpu_cluster_pm_enter - CPU cluster low power entry notifier
134 *
135 * Notifies listeners that all cpus in a power domain are entering a low power
136 * state that may cause some blocks in the same power domain to reset.
137 *
138 * Must be called after cpu_pm_enter has been called on all cpus in the power
139 * domain, and before cpu_pm_exit has been called on any cpu in the power
140 * domain. Notified drivers can include VFP co-processor, interrupt controller
141 * and its PM extensions, local CPU timers context save/restore which
142 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
143 *
144 * Must be called with interrupts disabled.
145 *
146 * Return conditions are same as __raw_notifier_call_chain.
147 */
148int cpu_cluster_pm_enter(void)
149{
150 return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED);
151}
152EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
153
154/**
155 * cpu_cluster_pm_exit - CPU cluster low power exit notifier
156 *
157 * Notifies listeners that all cpus in a power domain are exiting form a
158 * low power state that may have caused some blocks in the same power domain
159 * to reset.
160 *
161 * Must be called after cpu_cluster_pm_enter has been called for the power
162 * domain, and before cpu_pm_exit has been called on any cpu in the power
163 * domain. Notified drivers can include VFP co-processor, interrupt controller
164 * and its PM extensions, local CPU timers context save/restore which
165 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
166 *
167 * Return conditions are same as __raw_notifier_call_chain.
168 */
169int cpu_cluster_pm_exit(void)
170{
171 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT);
172}
173EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
174
175#ifdef CONFIG_PM
176static int cpu_pm_suspend(void)
177{
178 int ret;
179
180 ret = cpu_pm_enter();
181 if (ret)
182 return ret;
183
184 ret = cpu_cluster_pm_enter();
185 return ret;
186}
187
188static void cpu_pm_resume(void)
189{
190 cpu_cluster_pm_exit();
191 cpu_pm_exit();
192}
193
194static struct syscore_ops cpu_pm_syscore_ops = {
195 .suspend = cpu_pm_suspend,
196 .resume = cpu_pm_resume,
197};
198
199static int cpu_pm_init(void)
200{
201 register_syscore_ops(&cpu_pm_syscore_ops);
202 return 0;
203}
204core_initcall(cpu_pm_init);
205#endif