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 static ATOMIC_NOTIFIER_HEAD(cpu_pm_notifier_chain); 17 18 static 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 */ 45 int cpu_pm_register_notifier(struct notifier_block *nb) 46 { 47 return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb); 48 } 49 EXPORT_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 */ 60 int cpu_pm_unregister_notifier(struct notifier_block *nb) 61 { 62 return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb); 63 } 64 EXPORT_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 */ 81 int cpu_pm_enter(void) 82 { 83 int nr_calls = 0; 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 } 96 EXPORT_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 */ 110 int cpu_pm_exit(void) 111 { 112 return cpu_pm_notify(CPU_PM_EXIT, -1, NULL); 113 } 114 EXPORT_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 */ 132 int cpu_cluster_pm_enter(void) 133 { 134 int nr_calls = 0; 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 } 147 EXPORT_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 */ 164 int cpu_cluster_pm_exit(void) 165 { 166 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL); 167 } 168 EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit); 169 170 #ifdef CONFIG_PM 171 static 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 } 182 183 static void cpu_pm_resume(void) 184 { 185 cpu_cluster_pm_exit(); 186 cpu_pm_exit(); 187 } 188 189 static struct syscore_ops cpu_pm_syscore_ops = { 190 .suspend = cpu_pm_suspend, 191 .resume = cpu_pm_resume, 192 }; 193 194 static int cpu_pm_init(void) 195 { 196 register_syscore_ops(&cpu_pm_syscore_ops); 197 return 0; 198 } 199 core_initcall(cpu_pm_init); 200 #endif 201