Root/kernel/cpu_pm.c

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
234

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