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) 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 rcu_irq_exit_irqson(); 30 31 return notifier_to_errno(ret); 32 } 33 34 static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down) 35 { 36 int ret; 37 38 rcu_irq_enter_irqson(); 39 ret = atomic_notifier_call_chain_robust(&cpu_pm_notifier_chain, event_up, event_down, NULL); 40 rcu_irq_exit_irqson(); 41 42 return notifier_to_errno(ret); 43 } 44 45 /** 46 * cpu_pm_register_notifier - register a driver with cpu_pm 47 * @nb: notifier block to register 48 * 49 * Add a driver to a list of drivers that are notified about 50 * CPU and CPU cluster low power entry and exit. 51 * 52 * This function may sleep, and has the same return conditions as 53 * raw_notifier_chain_register. 54 */ 55 int cpu_pm_register_notifier(struct notifier_block *nb) 56 { 57 return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb); 58 } 59 EXPORT_SYMBOL_GPL(cpu_pm_register_notifier); 60 61 /** 62 * cpu_pm_unregister_notifier - unregister a driver with cpu_pm 63 * @nb: notifier block to be unregistered 64 * 65 * Remove a driver from the CPU PM notifier list. 66 * 67 * This function may sleep, and has the same return conditions as 68 * raw_notifier_chain_unregister. 69 */ 70 int cpu_pm_unregister_notifier(struct notifier_block *nb) 71 { 72 return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb); 73 } 74 EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier); 75 76 /** 77 * cpu_pm_enter - CPU low power entry notifier 78 * 79 * Notifies listeners that a single CPU is entering a low power state that may 80 * cause some blocks in the same power domain as the cpu to reset. 81 * 82 * Must be called on the affected CPU with interrupts disabled. Platform is 83 * responsible for ensuring that cpu_pm_enter is not called twice on the same 84 * CPU before cpu_pm_exit is called. Notified drivers can include VFP 85 * co-processor, interrupt controller and its PM extensions, local CPU 86 * timers context save/restore which shouldn't be interrupted. Hence it 87 * must be called with interrupts disabled. 88 * 89 * Return conditions are same as __raw_notifier_call_chain. 90 */ 91 int cpu_pm_enter(void) 92 { 93 return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED); 94 } 95 EXPORT_SYMBOL_GPL(cpu_pm_enter); 96 97 /** 98 * cpu_pm_exit - CPU low power exit notifier 99 * 100 * Notifies listeners that a single CPU is exiting a low power state that may 101 * have caused some blocks in the same power domain as the cpu to reset. 102 * 103 * Notified drivers can include VFP co-processor, interrupt controller 104 * and its PM extensions, local CPU timers context save/restore which 105 * shouldn't be interrupted. Hence it must be called with interrupts disabled. 106 * 107 * Return conditions are same as __raw_notifier_call_chain. 108 */ 109 int cpu_pm_exit(void) 110 { 111 return cpu_pm_notify(CPU_PM_EXIT); 112 } 113 EXPORT_SYMBOL_GPL(cpu_pm_exit); 114 115 /** 116 * cpu_cluster_pm_enter - CPU cluster low power entry notifier 117 * 118 * Notifies listeners that all cpus in a power domain are entering a low power 119 * state that may cause some blocks in the same power domain to reset. 120 * 121 * Must be called after cpu_pm_enter has been called on all cpus in the power 122 * domain, and before cpu_pm_exit has been called on any cpu in the power 123 * domain. Notified drivers can include VFP co-processor, interrupt controller 124 * and its PM extensions, local CPU timers context save/restore which 125 * shouldn't be interrupted. Hence it must be called with interrupts disabled. 126 * 127 * Must be called with interrupts disabled. 128 * 129 * Return conditions are same as __raw_notifier_call_chain. 130 */ 131 int cpu_cluster_pm_enter(void) 132 { 133 return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED); 134 } 135 EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter); 136 137 /** 138 * cpu_cluster_pm_exit - CPU cluster low power exit notifier 139 * 140 * Notifies listeners that all cpus in a power domain are exiting form a 141 * low power state that may have caused some blocks in the same power domain 142 * to reset. 143 * 144 * Must be called after cpu_cluster_pm_enter has been called for the power 145 * domain, and before cpu_pm_exit has been called on any cpu in the power 146 * domain. Notified drivers can include VFP co-processor, interrupt controller 147 * and its PM extensions, local CPU timers context save/restore which 148 * shouldn't be interrupted. Hence it must be called with interrupts disabled. 149 * 150 * Return conditions are same as __raw_notifier_call_chain. 151 */ 152 int cpu_cluster_pm_exit(void) 153 { 154 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT); 155 } 156 EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit); 157 158 #ifdef CONFIG_PM 159 static int cpu_pm_suspend(void) 160 { 161 int ret; 162 163 ret = cpu_pm_enter(); 164 if (ret) 165 return ret; 166 167 ret = cpu_cluster_pm_enter(); 168 return ret; 169 } 170 171 static void cpu_pm_resume(void) 172 { 173 cpu_cluster_pm_exit(); 174 cpu_pm_exit(); 175 } 176 177 static struct syscore_ops cpu_pm_syscore_ops = { 178 .suspend = cpu_pm_suspend, 179 .resume = cpu_pm_resume, 180 }; 181 182 static int cpu_pm_init(void) 183 { 184 register_syscore_ops(&cpu_pm_syscore_ops); 185 return 0; 186 } 187 core_initcall(cpu_pm_init); 188 #endif 189