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/*
  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 ATOMIC_NOTIFIER_HEAD(cpu_pm_notifier_chain);
 
 
 
 
 
 
 
 
 
 
 
 26
 27static 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 */
 54int cpu_pm_register_notifier(struct notifier_block *nb)
 55{
 56	return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb);
 
 
 
 
 
 
 57}
 58EXPORT_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 */
 69int cpu_pm_unregister_notifier(struct notifier_block *nb)
 70{
 71	return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
 
 
 
 
 
 
 72}
 73EXPORT_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 */
 90int 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}
105EXPORT_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 */
119int cpu_pm_exit(void)
120{
121	return cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
122}
123EXPORT_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 */
141int 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}
156EXPORT_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 */
173int cpu_cluster_pm_exit(void)
174{
175	return cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
176}
177EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
178
179#ifdef CONFIG_PM
180static 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
192static void cpu_pm_resume(void)
193{
194	cpu_cluster_pm_exit();
195	cpu_pm_exit();
196}
197
198static struct syscore_ops cpu_pm_syscore_ops = {
199	.suspend = cpu_pm_suspend,
200	.resume = cpu_pm_resume,
201};
202
203static int cpu_pm_init(void)
204{
205	register_syscore_ops(&cpu_pm_syscore_ops);
206	return 0;
207}
208core_initcall(cpu_pm_init);
209#endif