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