1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * Copyright (C) 2011 Google, Inc. 3 * Copyright (C) 2011 Google, Inc.
4 * 4 *
5 * Author: 5 * Author:
6 * Colin Cross <ccross@android.com> 6 * Colin Cross <ccross@android.com>
7 */ 7 */
8 8
9 #include <linux/kernel.h> 9 #include <linux/kernel.h>
10 #include <linux/cpu_pm.h> 10 #include <linux/cpu_pm.h>
11 #include <linux/module.h> 11 #include <linux/module.h>
12 #include <linux/notifier.h> 12 #include <linux/notifier.h>
13 #include <linux/spinlock.h> 13 #include <linux/spinlock.h>
14 #include <linux/syscore_ops.h> 14 #include <linux/syscore_ops.h>
15 15
16 /* 16 /*
17 * atomic_notifiers use a spinlock_t, which ca 17 * atomic_notifiers use a spinlock_t, which can block under PREEMPT_RT.
18 * Notifications for cpu_pm will be issued by 18 * Notifications for cpu_pm will be issued by the idle task itself, which can
19 * never block, IOW it requires using a raw_sp 19 * never block, IOW it requires using a raw_spinlock_t.
20 */ 20 */
21 static struct { 21 static struct {
22 struct raw_notifier_head chain; 22 struct raw_notifier_head chain;
23 raw_spinlock_t lock; 23 raw_spinlock_t lock;
24 } cpu_pm_notifier = { 24 } cpu_pm_notifier = {
25 .chain = RAW_NOTIFIER_INIT(cpu_pm_noti 25 .chain = RAW_NOTIFIER_INIT(cpu_pm_notifier.chain),
26 .lock = __RAW_SPIN_LOCK_UNLOCKED(cpu_ 26 .lock = __RAW_SPIN_LOCK_UNLOCKED(cpu_pm_notifier.lock),
27 }; 27 };
28 28
29 static int cpu_pm_notify(enum cpu_pm_event eve 29 static int cpu_pm_notify(enum cpu_pm_event event)
30 { 30 {
31 int ret; 31 int ret;
32 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 rcu_irq_enter_irqson();
33 rcu_read_lock(); 39 rcu_read_lock();
34 ret = raw_notifier_call_chain(&cpu_pm_ 40 ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
35 rcu_read_unlock(); 41 rcu_read_unlock();
>> 42 rcu_irq_exit_irqson();
36 43
37 return notifier_to_errno(ret); 44 return notifier_to_errno(ret);
38 } 45 }
39 46
40 static int cpu_pm_notify_robust(enum cpu_pm_ev 47 static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down)
41 { 48 {
42 unsigned long flags; 49 unsigned long flags;
43 int ret; 50 int ret;
44 51
>> 52 rcu_irq_enter_irqson();
45 raw_spin_lock_irqsave(&cpu_pm_notifier 53 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
46 ret = raw_notifier_call_chain_robust(& 54 ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
47 raw_spin_unlock_irqrestore(&cpu_pm_not 55 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
>> 56 rcu_irq_exit_irqson();
48 57
49 return notifier_to_errno(ret); 58 return notifier_to_errno(ret);
50 } 59 }
51 60
52 /** 61 /**
53 * cpu_pm_register_notifier - register a drive 62 * cpu_pm_register_notifier - register a driver with cpu_pm
54 * @nb: notifier block to register 63 * @nb: notifier block to register
55 * 64 *
56 * Add a driver to a list of drivers that are 65 * Add a driver to a list of drivers that are notified about
57 * CPU and CPU cluster low power entry and exi 66 * CPU and CPU cluster low power entry and exit.
58 * 67 *
59 * This function has the same return condition 68 * This function has the same return conditions as raw_notifier_chain_register.
60 */ 69 */
61 int cpu_pm_register_notifier(struct notifier_b 70 int cpu_pm_register_notifier(struct notifier_block *nb)
62 { 71 {
63 unsigned long flags; 72 unsigned long flags;
64 int ret; 73 int ret;
65 74
66 raw_spin_lock_irqsave(&cpu_pm_notifier 75 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
67 ret = raw_notifier_chain_register(&cpu 76 ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb);
68 raw_spin_unlock_irqrestore(&cpu_pm_not 77 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
69 return ret; 78 return ret;
70 } 79 }
71 EXPORT_SYMBOL_GPL(cpu_pm_register_notifier); 80 EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
72 81
73 /** 82 /**
74 * cpu_pm_unregister_notifier - unregister a d 83 * cpu_pm_unregister_notifier - unregister a driver with cpu_pm
75 * @nb: notifier block to be unregistered 84 * @nb: notifier block to be unregistered
76 * 85 *
77 * Remove a driver from the CPU PM notifier li 86 * Remove a driver from the CPU PM notifier list.
78 * 87 *
79 * This function has the same return condition 88 * This function has the same return conditions as raw_notifier_chain_unregister.
80 */ 89 */
81 int cpu_pm_unregister_notifier(struct notifier 90 int cpu_pm_unregister_notifier(struct notifier_block *nb)
82 { 91 {
83 unsigned long flags; 92 unsigned long flags;
84 int ret; 93 int ret;
85 94
86 raw_spin_lock_irqsave(&cpu_pm_notifier 95 raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
87 ret = raw_notifier_chain_unregister(&c 96 ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb);
88 raw_spin_unlock_irqrestore(&cpu_pm_not 97 raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
89 return ret; 98 return ret;
90 } 99 }
91 EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier); 100 EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
92 101
93 /** 102 /**
94 * cpu_pm_enter - CPU low power entry notifier 103 * cpu_pm_enter - CPU low power entry notifier
95 * 104 *
96 * Notifies listeners that a single CPU is ent 105 * Notifies listeners that a single CPU is entering a low power state that may
97 * cause some blocks in the same power domain 106 * cause some blocks in the same power domain as the cpu to reset.
98 * 107 *
99 * Must be called on the affected CPU with int 108 * Must be called on the affected CPU with interrupts disabled. Platform is
100 * responsible for ensuring that cpu_pm_enter 109 * responsible for ensuring that cpu_pm_enter is not called twice on the same
101 * CPU before cpu_pm_exit is called. Notified 110 * CPU before cpu_pm_exit is called. Notified drivers can include VFP
102 * co-processor, interrupt controller and its 111 * co-processor, interrupt controller and its PM extensions, local CPU
103 * timers context save/restore which shouldn't 112 * timers context save/restore which shouldn't be interrupted. Hence it
104 * must be called with interrupts disabled. 113 * must be called with interrupts disabled.
105 * 114 *
106 * Return conditions are same as __raw_notifie 115 * Return conditions are same as __raw_notifier_call_chain.
107 */ 116 */
108 int cpu_pm_enter(void) 117 int cpu_pm_enter(void)
109 { 118 {
110 return cpu_pm_notify_robust(CPU_PM_ENT 119 return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
111 } 120 }
112 EXPORT_SYMBOL_GPL(cpu_pm_enter); 121 EXPORT_SYMBOL_GPL(cpu_pm_enter);
113 122
114 /** 123 /**
115 * cpu_pm_exit - CPU low power exit notifier 124 * cpu_pm_exit - CPU low power exit notifier
116 * 125 *
117 * Notifies listeners that a single CPU is exi 126 * Notifies listeners that a single CPU is exiting a low power state that may
118 * have caused some blocks in the same power d 127 * have caused some blocks in the same power domain as the cpu to reset.
119 * 128 *
120 * Notified drivers can include VFP co-process 129 * Notified drivers can include VFP co-processor, interrupt controller
121 * and its PM extensions, local CPU timers con 130 * and its PM extensions, local CPU timers context save/restore which
122 * shouldn't be interrupted. Hence it must be 131 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
123 * 132 *
124 * Return conditions are same as __raw_notifie 133 * Return conditions are same as __raw_notifier_call_chain.
125 */ 134 */
126 int cpu_pm_exit(void) 135 int cpu_pm_exit(void)
127 { 136 {
128 return cpu_pm_notify(CPU_PM_EXIT); 137 return cpu_pm_notify(CPU_PM_EXIT);
129 } 138 }
130 EXPORT_SYMBOL_GPL(cpu_pm_exit); 139 EXPORT_SYMBOL_GPL(cpu_pm_exit);
131 140
132 /** 141 /**
133 * cpu_cluster_pm_enter - CPU cluster low powe 142 * cpu_cluster_pm_enter - CPU cluster low power entry notifier
134 * 143 *
135 * Notifies listeners that all cpus in a power 144 * Notifies listeners that all cpus in a power domain are entering a low power
136 * state that may cause some blocks in the sam 145 * state that may cause some blocks in the same power domain to reset.
137 * 146 *
138 * Must be called after cpu_pm_enter has been 147 * 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 cal 148 * domain, and before cpu_pm_exit has been called on any cpu in the power
140 * domain. Notified drivers can include VFP co 149 * domain. Notified drivers can include VFP co-processor, interrupt controller
141 * and its PM extensions, local CPU timers con 150 * and its PM extensions, local CPU timers context save/restore which
142 * shouldn't be interrupted. Hence it must be 151 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
143 * 152 *
144 * Must be called with interrupts disabled. 153 * Must be called with interrupts disabled.
145 * 154 *
146 * Return conditions are same as __raw_notifie 155 * Return conditions are same as __raw_notifier_call_chain.
147 */ 156 */
148 int cpu_cluster_pm_enter(void) 157 int cpu_cluster_pm_enter(void)
149 { 158 {
150 return cpu_pm_notify_robust(CPU_CLUSTE 159 return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED);
151 } 160 }
152 EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter); 161 EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
153 162
154 /** 163 /**
155 * cpu_cluster_pm_exit - CPU cluster low power 164 * cpu_cluster_pm_exit - CPU cluster low power exit notifier
156 * 165 *
157 * Notifies listeners that all cpus in a power 166 * Notifies listeners that all cpus in a power domain are exiting form a
158 * low power state that may have caused some b 167 * low power state that may have caused some blocks in the same power domain
159 * to reset. 168 * to reset.
160 * 169 *
161 * Must be called after cpu_cluster_pm_enter h 170 * Must be called after cpu_cluster_pm_enter has been called for the power
162 * domain, and before cpu_pm_exit has been cal 171 * domain, and before cpu_pm_exit has been called on any cpu in the power
163 * domain. Notified drivers can include VFP co 172 * domain. Notified drivers can include VFP co-processor, interrupt controller
164 * and its PM extensions, local CPU timers con 173 * and its PM extensions, local CPU timers context save/restore which
165 * shouldn't be interrupted. Hence it must be 174 * shouldn't be interrupted. Hence it must be called with interrupts disabled.
166 * 175 *
167 * Return conditions are same as __raw_notifie 176 * Return conditions are same as __raw_notifier_call_chain.
168 */ 177 */
169 int cpu_cluster_pm_exit(void) 178 int cpu_cluster_pm_exit(void)
170 { 179 {
171 return cpu_pm_notify(CPU_CLUSTER_PM_EX 180 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT);
172 } 181 }
173 EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit); 182 EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
174 183
175 #ifdef CONFIG_PM 184 #ifdef CONFIG_PM
176 static int cpu_pm_suspend(void) 185 static int cpu_pm_suspend(void)
177 { 186 {
178 int ret; 187 int ret;
179 188
180 ret = cpu_pm_enter(); 189 ret = cpu_pm_enter();
181 if (ret) 190 if (ret)
182 return ret; 191 return ret;
183 192
184 ret = cpu_cluster_pm_enter(); 193 ret = cpu_cluster_pm_enter();
185 return ret; 194 return ret;
186 } 195 }
187 196
188 static void cpu_pm_resume(void) 197 static void cpu_pm_resume(void)
189 { 198 {
190 cpu_cluster_pm_exit(); 199 cpu_cluster_pm_exit();
191 cpu_pm_exit(); 200 cpu_pm_exit();
192 } 201 }
193 202
194 static struct syscore_ops cpu_pm_syscore_ops = 203 static struct syscore_ops cpu_pm_syscore_ops = {
195 .suspend = cpu_pm_suspend, 204 .suspend = cpu_pm_suspend,
196 .resume = cpu_pm_resume, 205 .resume = cpu_pm_resume,
197 }; 206 };
198 207
199 static int cpu_pm_init(void) 208 static int cpu_pm_init(void)
200 { 209 {
201 register_syscore_ops(&cpu_pm_syscore_o 210 register_syscore_ops(&cpu_pm_syscore_ops);
202 return 0; 211 return 0;
203 } 212 }
204 core_initcall(cpu_pm_init); 213 core_initcall(cpu_pm_init);
205 #endif 214 #endif
206 215
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