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1/*
2 * Copyright (C) 2011 Google, Inc.
3 *
4 * Author:
5 * Colin Cross <ccross@android.com>
6 *
7 * This software is licensed under the terms of the GNU General Public
8 * License version 2, as published by the Free Software Foundation, and
9 * may be copied, distributed, and modified under those terms.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 */
17
18#include <linux/kernel.h>
19#include <linux/cpu_pm.h>
20#include <linux/module.h>
21#include <linux/notifier.h>
22#include <linux/spinlock.h>
23#include <linux/syscore_ops.h>
24
25static DEFINE_RWLOCK(cpu_pm_notifier_lock);
26static RAW_NOTIFIER_HEAD(cpu_pm_notifier_chain);
27
28static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls)
29{
30 int ret;
31
32 ret = __raw_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL,
33 nr_to_call, nr_calls);
34
35 return notifier_to_errno(ret);
36}
37
38/**
39 * cpu_pm_register_notifier - register a driver with cpu_pm
40 * @nb: notifier block to register
41 *
42 * Add a driver to a list of drivers that are notified about
43 * CPU and CPU cluster low power entry and exit.
44 *
45 * This function may sleep, and has the same return conditions as
46 * raw_notifier_chain_register.
47 */
48int cpu_pm_register_notifier(struct notifier_block *nb)
49{
50 unsigned long flags;
51 int ret;
52
53 write_lock_irqsave(&cpu_pm_notifier_lock, flags);
54 ret = raw_notifier_chain_register(&cpu_pm_notifier_chain, nb);
55 write_unlock_irqrestore(&cpu_pm_notifier_lock, flags);
56
57 return ret;
58}
59EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
60
61/**
62 * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
63 * @nb: notifier block to be unregistered
64 *
65 * Remove a driver from the CPU PM notifier list.
66 *
67 * This function may sleep, and has the same return conditions as
68 * raw_notifier_chain_unregister.
69 */
70int cpu_pm_unregister_notifier(struct notifier_block *nb)
71{
72 unsigned long flags;
73 int ret;
74
75 write_lock_irqsave(&cpu_pm_notifier_lock, flags);
76 ret = raw_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
77 write_unlock_irqrestore(&cpu_pm_notifier_lock, flags);
78
79 return ret;
80}
81EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
82
83/**
84 * cpu_pm_enter - CPU low power entry notifier
85 *
86 * Notifies listeners that a single CPU is entering a low power state that may
87 * cause some blocks in the same power domain as the cpu to reset.
88 *
89 * Must be called on the affected CPU with interrupts disabled. Platform is
90 * responsible for ensuring that cpu_pm_enter is not called twice on the same
91 * CPU before cpu_pm_exit is called. Notified drivers can include VFP
92 * co-processor, interrupt controller and its PM extensions, local CPU
93 * timers context save/restore which shouldn't be interrupted. Hence it
94 * must be called with interrupts disabled.
95 *
96 * Return conditions are same as __raw_notifier_call_chain.
97 */
98int cpu_pm_enter(void)
99{
100 int nr_calls;
101 int ret = 0;
102
103 read_lock(&cpu_pm_notifier_lock);
104 ret = cpu_pm_notify(CPU_PM_ENTER, -1, &nr_calls);
105 if (ret)
106 /*
107 * Inform listeners (nr_calls - 1) about failure of CPU PM
108 * PM entry who are notified earlier to prepare for it.
109 */
110 cpu_pm_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
111 read_unlock(&cpu_pm_notifier_lock);
112
113 return ret;
114}
115EXPORT_SYMBOL_GPL(cpu_pm_enter);
116
117/**
118 * cpu_pm_exit - CPU low power exit notifier
119 *
120 * Notifies listeners that a single CPU is exiting a low power state that may
121 * have caused some blocks in the same power domain as the cpu to reset.
122 *
123 * Notified drivers can include VFP co-processor, interrupt controller
124 * and its PM extensions, local CPU timers context save/restore which
125 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
126 *
127 * Return conditions are same as __raw_notifier_call_chain.
128 */
129int cpu_pm_exit(void)
130{
131 int ret;
132
133 read_lock(&cpu_pm_notifier_lock);
134 ret = cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
135 read_unlock(&cpu_pm_notifier_lock);
136
137 return ret;
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 int nr_calls;
160 int ret = 0;
161
162 read_lock(&cpu_pm_notifier_lock);
163 ret = cpu_pm_notify(CPU_CLUSTER_PM_ENTER, -1, &nr_calls);
164 if (ret)
165 /*
166 * Inform listeners (nr_calls - 1) about failure of CPU cluster
167 * PM entry who are notified earlier to prepare for it.
168 */
169 cpu_pm_notify(CPU_CLUSTER_PM_ENTER_FAILED, nr_calls - 1, NULL);
170 read_unlock(&cpu_pm_notifier_lock);
171
172 return ret;
173}
174EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
175
176/**
177 * cpu_cluster_pm_exit - CPU cluster low power exit notifier
178 *
179 * Notifies listeners that all cpus in a power domain are exiting form a
180 * low power state that may have caused some blocks in the same power domain
181 * to reset.
182 *
183 * Must be called after cpu_pm_exit has been called on all cpus in the power
184 * domain, and before cpu_pm_exit has been called on any cpu in the power
185 * domain. Notified drivers can include VFP co-processor, interrupt controller
186 * and its PM extensions, local CPU timers context save/restore which
187 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
188 *
189 * Return conditions are same as __raw_notifier_call_chain.
190 */
191int cpu_cluster_pm_exit(void)
192{
193 int ret;
194
195 read_lock(&cpu_pm_notifier_lock);
196 ret = cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
197 read_unlock(&cpu_pm_notifier_lock);
198
199 return ret;
200}
201EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
202
203#ifdef CONFIG_PM
204static int cpu_pm_suspend(void)
205{
206 int ret;
207
208 ret = cpu_pm_enter();
209 if (ret)
210 return ret;
211
212 ret = cpu_cluster_pm_enter();
213 return ret;
214}
215
216static void cpu_pm_resume(void)
217{
218 cpu_cluster_pm_exit();
219 cpu_pm_exit();
220}
221
222static struct syscore_ops cpu_pm_syscore_ops = {
223 .suspend = cpu_pm_suspend,
224 .resume = cpu_pm_resume,
225};
226
227static int cpu_pm_init(void)
228{
229 register_syscore_ops(&cpu_pm_syscore_ops);
230 return 0;
231}
232core_initcall(cpu_pm_init);
233#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