| 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 | */ |
| 21 | static 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 | |
| 29 | static int cpu_pm_notify(enum cpu_pm_event event) |
| 30 | { |
| 31 | int ret; |
| 32 | |
| 33 | rcu_read_lock(); |
| 34 | ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL); |
| 35 | rcu_read_unlock(); |
| 36 | |
| 37 | return notifier_to_errno(ret); |
| 38 | } |
| 39 | |
| 40 | static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down) |
| 41 | { |
| 42 | unsigned long flags; |
| 43 | int ret; |
| 44 | |
| 45 | raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags); |
| 46 | ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL); |
| 47 | raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags); |
| 48 | |
| 49 | return notifier_to_errno(ret); |
| 50 | } |
| 51 | |
| 52 | /** |
| 53 | * cpu_pm_register_notifier - register a driver with cpu_pm |
| 54 | * @nb: notifier block to register |
| 55 | * |
| 56 | * Add a driver to a list of drivers that are notified about |
| 57 | * CPU and CPU cluster low power entry and exit. |
| 58 | * |
| 59 | * This function has the same return conditions as raw_notifier_chain_register. |
| 60 | */ |
| 61 | int cpu_pm_register_notifier(struct notifier_block *nb) |
| 62 | { |
| 63 | unsigned long flags; |
| 64 | int ret; |
| 65 | |
| 66 | raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags); |
| 67 | ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb); |
| 68 | raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags); |
| 69 | return ret; |
| 70 | } |
| 71 | EXPORT_SYMBOL_GPL(cpu_pm_register_notifier); |
| 72 | |
| 73 | /** |
| 74 | * cpu_pm_unregister_notifier - unregister a driver with cpu_pm |
| 75 | * @nb: notifier block to be unregistered |
| 76 | * |
| 77 | * Remove a driver from the CPU PM notifier list. |
| 78 | * |
| 79 | * This function has the same return conditions as raw_notifier_chain_unregister. |
| 80 | */ |
| 81 | int cpu_pm_unregister_notifier(struct notifier_block *nb) |
| 82 | { |
| 83 | unsigned long flags; |
| 84 | int ret; |
| 85 | |
| 86 | raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags); |
| 87 | ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb); |
| 88 | raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags); |
| 89 | return ret; |
| 90 | } |
| 91 | EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier); |
| 92 | |
| 93 | /** |
| 94 | * cpu_pm_enter - CPU low power entry notifier |
| 95 | * |
| 96 | * Notifies listeners that a single CPU is entering a low power state that may |
| 97 | * cause some blocks in the same power domain as the cpu to reset. |
| 98 | * |
| 99 | * Must be called on the affected CPU with interrupts disabled. Platform is |
| 100 | * responsible for ensuring that cpu_pm_enter is not called twice on the same |
| 101 | * CPU before cpu_pm_exit is called. Notified drivers can include VFP |
| 102 | * co-processor, interrupt controller and its PM extensions, local CPU |
| 103 | * timers context save/restore which shouldn't be interrupted. Hence it |
| 104 | * must be called with interrupts disabled. |
| 105 | * |
| 106 | * Return conditions are same as __raw_notifier_call_chain. |
| 107 | */ |
| 108 | int cpu_pm_enter(void) |
| 109 | { |
| 110 | return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED); |
| 111 | } |
| 112 | EXPORT_SYMBOL_GPL(cpu_pm_enter); |
| 113 | |
| 114 | /** |
| 115 | * cpu_pm_exit - CPU low power exit notifier |
| 116 | * |
| 117 | * Notifies listeners that a single CPU is exiting a low power state that may |
| 118 | * have caused some blocks in the same power domain as the cpu to reset. |
| 119 | * |
| 120 | * Notified drivers can include VFP co-processor, interrupt controller |
| 121 | * and its PM extensions, local CPU timers context save/restore which |
| 122 | * shouldn't be interrupted. Hence it must be called with interrupts disabled. |
| 123 | * |
| 124 | * Return conditions are same as __raw_notifier_call_chain. |
| 125 | */ |
| 126 | int cpu_pm_exit(void) |
| 127 | { |
| 128 | return cpu_pm_notify(CPU_PM_EXIT); |
| 129 | } |
| 130 | EXPORT_SYMBOL_GPL(cpu_pm_exit); |
| 131 | |
| 132 | /** |
| 133 | * cpu_cluster_pm_enter - CPU cluster low power entry notifier |
| 134 | * |
| 135 | * Notifies listeners that all cpus in a power domain are entering a low power |
| 136 | * state that may cause some blocks in the same power domain to reset. |
| 137 | * |
| 138 | * 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 called on any cpu in the power |
| 140 | * domain. Notified drivers can include VFP co-processor, interrupt controller |
| 141 | * and its PM extensions, local CPU timers context save/restore which |
| 142 | * shouldn't be interrupted. Hence it must be called with interrupts disabled. |
| 143 | * |
| 144 | * Must be called with interrupts disabled. |
| 145 | * |
| 146 | * Return conditions are same as __raw_notifier_call_chain. |
| 147 | */ |
| 148 | int cpu_cluster_pm_enter(void) |
| 149 | { |
| 150 | return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED); |
| 151 | } |
| 152 | EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter); |
| 153 | |
| 154 | /** |
| 155 | * cpu_cluster_pm_exit - CPU cluster low power exit notifier |
| 156 | * |
| 157 | * Notifies listeners that all cpus in a power domain are exiting form a |
| 158 | * low power state that may have caused some blocks in the same power domain |
| 159 | * to reset. |
| 160 | * |
| 161 | * Must be called after cpu_cluster_pm_enter has been called for the power |
| 162 | * domain, and before cpu_pm_exit has been called on any cpu in the power |
| 163 | * domain. Notified drivers can include VFP co-processor, interrupt controller |
| 164 | * and its PM extensions, local CPU timers context save/restore which |
| 165 | * shouldn't be interrupted. Hence it must be called with interrupts disabled. |
| 166 | * |
| 167 | * Return conditions are same as __raw_notifier_call_chain. |
| 168 | */ |
| 169 | int cpu_cluster_pm_exit(void) |
| 170 | { |
| 171 | return cpu_pm_notify(CPU_CLUSTER_PM_EXIT); |
| 172 | } |
| 173 | EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit); |
| 174 | |
| 175 | #ifdef CONFIG_PM |
| 176 | static int cpu_pm_suspend(void) |
| 177 | { |
| 178 | int ret; |
| 179 | |
| 180 | ret = cpu_pm_enter(); |
| 181 | if (ret) |
| 182 | return ret; |
| 183 | |
| 184 | ret = cpu_cluster_pm_enter(); |
| 185 | return ret; |
| 186 | } |
| 187 | |
| 188 | static void cpu_pm_resume(void) |
| 189 | { |
| 190 | cpu_cluster_pm_exit(); |
| 191 | cpu_pm_exit(); |
| 192 | } |
| 193 | |
| 194 | static struct syscore_ops cpu_pm_syscore_ops = { |
| 195 | .suspend = cpu_pm_suspend, |
| 196 | .resume = cpu_pm_resume, |
| 197 | }; |
| 198 | |
| 199 | static int cpu_pm_init(void) |
| 200 | { |
| 201 | register_syscore_ops(&cpu_pm_syscore_ops); |
| 202 | return 0; |
| 203 | } |
| 204 | core_initcall(cpu_pm_init); |
| 205 | #endif |