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	/*
 34	 * This introduces a RCU read critical section, which could be
 35	 * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know
 36	 * this.
 37	 */
 38	ct_irq_enter_irqson();
 39	rcu_read_lock();
 40	ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
 41	rcu_read_unlock();
 42	ct_irq_exit_irqson();
 43
 44	return notifier_to_errno(ret);
 45}
 46
 47static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down)
 48{
 49	unsigned long flags;
 50	int ret;
 51
 52	ct_irq_enter_irqson();
 53	raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
 54	ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
 55	raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
 56	ct_irq_exit_irqson();
 57
 58	return notifier_to_errno(ret);
 59}
 60
 61/**
 62 * cpu_pm_register_notifier - register a driver with cpu_pm
 63 * @nb: notifier block to register
 64 *
 65 * Add a driver to a list of drivers that are notified about
 66 * CPU and CPU cluster low power entry and exit.
 67 *
 68 * This function has the same return conditions as raw_notifier_chain_register.
 69 */
 70int cpu_pm_register_notifier(struct notifier_block *nb)
 71{
 72	unsigned long flags;
 73	int ret;
 74
 75	raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
 76	ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb);
 77	raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
 78	return ret;
 79}
 80EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
 81
 82/**
 83 * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
 84 * @nb: notifier block to be unregistered
 85 *
 86 * Remove a driver from the CPU PM notifier list.
 87 *
 88 * This function has the same return conditions as raw_notifier_chain_unregister.
 89 */
 90int cpu_pm_unregister_notifier(struct notifier_block *nb)
 91{
 92	unsigned long flags;
 93	int ret;
 94
 95	raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
 96	ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb);
 97	raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
 98	return ret;
 99}
100EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
101
102/**
103 * cpu_pm_enter - CPU low power entry notifier
104 *
105 * Notifies listeners that a single CPU is entering a low power state that may
106 * cause some blocks in the same power domain as the cpu to reset.
107 *
108 * Must be called on the affected CPU with interrupts disabled.  Platform is
109 * responsible for ensuring that cpu_pm_enter is not called twice on the same
110 * CPU before cpu_pm_exit is called. Notified drivers can include VFP
111 * co-processor, interrupt controller and its PM extensions, local CPU
112 * timers context save/restore which shouldn't be interrupted. Hence it
113 * must be called with interrupts disabled.
114 *
115 * Return conditions are same as __raw_notifier_call_chain.
116 */
117int cpu_pm_enter(void)
118{
119	return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
120}
121EXPORT_SYMBOL_GPL(cpu_pm_enter);
122
123/**
124 * cpu_pm_exit - CPU low power exit notifier
125 *
126 * Notifies listeners that a single CPU is exiting a low power state that may
127 * have caused some blocks in the same power domain as the cpu to reset.
128 *
129 * Notified drivers can include VFP co-processor, interrupt controller
130 * and its PM extensions, local CPU timers context save/restore which
131 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
132 *
133 * Return conditions are same as __raw_notifier_call_chain.
134 */
135int cpu_pm_exit(void)
136{
137	return cpu_pm_notify(CPU_PM_EXIT);
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	return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED);
160}
161EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
162
163/**
164 * cpu_cluster_pm_exit - CPU cluster low power exit notifier
165 *
166 * Notifies listeners that all cpus in a power domain are exiting form a
167 * low power state that may have caused some blocks in the same power domain
168 * to reset.
169 *
170 * Must be called after cpu_cluster_pm_enter has been called for the power
171 * domain, and before cpu_pm_exit has been called on any cpu in the power
172 * domain. Notified drivers can include VFP co-processor, interrupt controller
173 * and its PM extensions, local CPU timers context save/restore which
174 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
175 *
176 * Return conditions are same as __raw_notifier_call_chain.
177 */
178int cpu_cluster_pm_exit(void)
179{
180	return cpu_pm_notify(CPU_CLUSTER_PM_EXIT);
181}
182EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
183
184#ifdef CONFIG_PM
185static int cpu_pm_suspend(void)
186{
187	int ret;
188
189	ret = cpu_pm_enter();
190	if (ret)
191		return ret;
192
193	ret = cpu_cluster_pm_enter();
194	return ret;
195}
196
197static void cpu_pm_resume(void)
198{
199	cpu_cluster_pm_exit();
200	cpu_pm_exit();
201}
202
203static struct syscore_ops cpu_pm_syscore_ops = {
204	.suspend = cpu_pm_suspend,
205	.resume = cpu_pm_resume,
206};
207
208static int cpu_pm_init(void)
209{
210	register_syscore_ops(&cpu_pm_syscore_ops);
211	return 0;
212}
213core_initcall(cpu_pm_init);
214#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