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 25 static ATOMIC_NOTIFIER_HEAD(cpu_pm_notifier_chain); 26 27 static 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 */ 54 int cpu_pm_register_notifier(struct notifier_block *nb) 55 { 56 return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb); 57 } 58 EXPORT_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 */ 69 int cpu_pm_unregister_notifier(struct notifier_block *nb) 70 { 71 return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb); 72 } 73 EXPORT_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 */ 90 int 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 } 105 EXPORT_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 */ 119 int cpu_pm_exit(void) 120 { 121 return cpu_pm_notify(CPU_PM_EXIT, -1, NULL); 122 } 123 EXPORT_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 */ 141 int 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 } 156 EXPORT_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 */ 173 int cpu_cluster_pm_exit(void) 174 { 175 return cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL); 176 } 177 EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit); 178 179 #ifdef CONFIG_PM 180 static 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 } 191 192 static void cpu_pm_resume(void) 193 { 194 cpu_cluster_pm_exit(); 195 cpu_pm_exit(); 196 } 197 198 static struct syscore_ops cpu_pm_syscore_ops = { 199 .suspend = cpu_pm_suspend, 200 .resume = cpu_pm_resume, 201 }; 202 203 static int cpu_pm_init(void) 204 { 205 register_syscore_ops(&cpu_pm_syscore_ops); 206 return 0; 207 } 208 core_initcall(cpu_pm_init); 209 #endif 210