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
25 static ATOMIC_NOTIFIER_HEAD(cpu_pm_notifier_chain);
26
cpu_pm_notify(enum cpu_pm_event event,int nr_to_call,int * nr_calls)27 static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls)
28 {
29 int ret;
30
31 /*
32 * __atomic_notifier_call_chain has a RCU read critical section, which
33 * could be disfunctional in cpu idle. Copy RCU_NONIDLE code to let
34 * RCU know this.
35 */
36 rcu_irq_enter_irqson();
37 ret = __atomic_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL,
38 nr_to_call, nr_calls);
39 rcu_irq_exit_irqson();
40
41 return notifier_to_errno(ret);
42 }
43
44 /**
45 * cpu_pm_register_notifier - register a driver with cpu_pm
46 * @nb: notifier block to register
47 *
48 * Add a driver to a list of drivers that are notified about
49 * CPU and CPU cluster low power entry and exit.
50 *
51 * This function may sleep, and has the same return conditions as
52 * raw_notifier_chain_register.
53 */
cpu_pm_register_notifier(struct notifier_block * nb)54 int cpu_pm_register_notifier(struct notifier_block *nb)
55 {
56 return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb);
57 }
58 EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
59
60 /**
61 * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
62 * @nb: notifier block to be unregistered
63 *
64 * Remove a driver from the CPU PM notifier list.
65 *
66 * This function may sleep, and has the same return conditions as
67 * raw_notifier_chain_unregister.
68 */
cpu_pm_unregister_notifier(struct notifier_block * nb)69 int cpu_pm_unregister_notifier(struct notifier_block *nb)
70 {
71 return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
72 }
73 EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
74
75 /**
76 * cpu_pm_enter - CPU low power entry notifier
77 *
78 * Notifies listeners that a single CPU is entering a low power state that may
79 * cause some blocks in the same power domain as the cpu to reset.
80 *
81 * Must be called on the affected CPU with interrupts disabled. Platform is
82 * responsible for ensuring that cpu_pm_enter is not called twice on the same
83 * CPU before cpu_pm_exit is called. Notified drivers can include VFP
84 * co-processor, interrupt controller and its PM extensions, local CPU
85 * timers context save/restore which shouldn't be interrupted. Hence it
86 * must be called with interrupts disabled.
87 *
88 * Return conditions are same as __raw_notifier_call_chain.
89 */
cpu_pm_enter(void)90 int cpu_pm_enter(void)
91 {
92 int nr_calls;
93 int ret = 0;
94
95 ret = cpu_pm_notify(CPU_PM_ENTER, -1, &nr_calls);
96 if (ret)
97 /*
98 * Inform listeners (nr_calls - 1) about failure of CPU PM
99 * PM entry who are notified earlier to prepare for it.
100 */
101 cpu_pm_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
102
103 return ret;
104 }
105 EXPORT_SYMBOL_GPL(cpu_pm_enter);
106
107 /**
108 * cpu_pm_exit - CPU low power exit notifier
109 *
110 * Notifies listeners that a single CPU is exiting a low power state that may
111 * have caused some blocks in the same power domain as the cpu to reset.
112 *
113 * Notified drivers can include VFP co-processor, interrupt controller
114 * and its PM extensions, local CPU timers context save/restore which
115 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
116 *
117 * Return conditions are same as __raw_notifier_call_chain.
118 */
cpu_pm_exit(void)119 int cpu_pm_exit(void)
120 {
121 return cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
122 }
123 EXPORT_SYMBOL_GPL(cpu_pm_exit);
124
125 /**
126 * cpu_cluster_pm_enter - CPU cluster low power entry notifier
127 *
128 * Notifies listeners that all cpus in a power domain are entering a low power
129 * state that may cause some blocks in the same power domain to reset.
130 *
131 * Must be called after cpu_pm_enter has been called on all cpus in the power
132 * domain, and before cpu_pm_exit has been called on any cpu in the power
133 * domain. Notified drivers can include VFP co-processor, interrupt controller
134 * and its PM extensions, local CPU timers context save/restore which
135 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
136 *
137 * Must be called with interrupts disabled.
138 *
139 * Return conditions are same as __raw_notifier_call_chain.
140 */
cpu_cluster_pm_enter(void)141 int cpu_cluster_pm_enter(void)
142 {
143 int nr_calls;
144 int ret = 0;
145
146 ret = cpu_pm_notify(CPU_CLUSTER_PM_ENTER, -1, &nr_calls);
147 if (ret)
148 /*
149 * Inform listeners (nr_calls - 1) about failure of CPU cluster
150 * PM entry who are notified earlier to prepare for it.
151 */
152 cpu_pm_notify(CPU_CLUSTER_PM_ENTER_FAILED, nr_calls - 1, NULL);
153
154 return ret;
155 }
156 EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
157
158 /**
159 * cpu_cluster_pm_exit - CPU cluster low power exit notifier
160 *
161 * Notifies listeners that all cpus in a power domain are exiting form a
162 * low power state that may have caused some blocks in the same power domain
163 * to reset.
164 *
165 * Must be called after cpu_cluster_pm_enter has been called for the power
166 * domain, and before cpu_pm_exit has been called on any cpu in the power
167 * domain. Notified drivers can include VFP co-processor, interrupt controller
168 * and its PM extensions, local CPU timers context save/restore which
169 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
170 *
171 * Return conditions are same as __raw_notifier_call_chain.
172 */
cpu_cluster_pm_exit(void)173 int cpu_cluster_pm_exit(void)
174 {
175 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
176 }
177 EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
178
179 #ifdef CONFIG_PM
cpu_pm_suspend(void)180 static int cpu_pm_suspend(void)
181 {
182 int ret;
183
184 ret = cpu_pm_enter();
185 if (ret)
186 return ret;
187
188 ret = cpu_cluster_pm_enter();
189 return ret;
190 }
191
cpu_pm_resume(void)192 static void cpu_pm_resume(void)
193 {
194 cpu_cluster_pm_exit();
195 cpu_pm_exit();
196 }
197
198 static struct syscore_ops cpu_pm_syscore_ops = {
199 .suspend = cpu_pm_suspend,
200 .resume = cpu_pm_resume,
201 };
202
cpu_pm_init(void)203 static int cpu_pm_init(void)
204 {
205 register_syscore_ops(&cpu_pm_syscore_ops);
206 return 0;
207 }
208 core_initcall(cpu_pm_init);
209 #endif
210
