diff options
Diffstat (limited to 'kernel/cpu_pm.c')
| -rw-r--r-- | kernel/cpu_pm.c | 214 |
1 files changed, 214 insertions, 0 deletions
diff --git a/kernel/cpu_pm.c b/kernel/cpu_pm.c new file mode 100644 index 000000000..ba4ba71fa --- /dev/null +++ b/kernel/cpu_pm.c @@ -0,0 +1,214 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2011 Google, Inc. + * + * Author: + * Colin Cross <ccross@android.com> + */ + +#include <linux/kernel.h> +#include <linux/cpu_pm.h> +#include <linux/module.h> +#include <linux/notifier.h> +#include <linux/spinlock.h> +#include <linux/syscore_ops.h> + +/* + * atomic_notifiers use a spinlock_t, which can block under PREEMPT_RT. + * Notifications for cpu_pm will be issued by the idle task itself, which can + * never block, IOW it requires using a raw_spinlock_t. + */ +static struct { + struct raw_notifier_head chain; + raw_spinlock_t lock; +} cpu_pm_notifier = { + .chain = RAW_NOTIFIER_INIT(cpu_pm_notifier.chain), + .lock = __RAW_SPIN_LOCK_UNLOCKED(cpu_pm_notifier.lock), +}; + +static int cpu_pm_notify(enum cpu_pm_event event) +{ + int ret; + + /* + * This introduces a RCU read critical section, which could be + * disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know + * this. + */ + ct_irq_enter_irqson(); + rcu_read_lock(); + ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL); + rcu_read_unlock(); + ct_irq_exit_irqson(); + + return notifier_to_errno(ret); +} + +static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down) +{ + unsigned long flags; + int ret; + + ct_irq_enter_irqson(); + raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags); + ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL); + raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags); + ct_irq_exit_irqson(); + + return notifier_to_errno(ret); +} + +/** + * cpu_pm_register_notifier - register a driver with cpu_pm + * @nb: notifier block to register + * + * Add a driver to a list of drivers that are notified about + * CPU and CPU cluster low power entry and exit. + * + * This function has the same return conditions as raw_notifier_chain_register. + */ +int cpu_pm_register_notifier(struct notifier_block *nb) +{ + unsigned long flags; + int ret; + + raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags); + ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb); + raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags); + return ret; +} +EXPORT_SYMBOL_GPL(cpu_pm_register_notifier); + +/** + * cpu_pm_unregister_notifier - unregister a driver with cpu_pm + * @nb: notifier block to be unregistered + * + * Remove a driver from the CPU PM notifier list. + * + * This function has the same return conditions as raw_notifier_chain_unregister. + */ +int cpu_pm_unregister_notifier(struct notifier_block *nb) +{ + unsigned long flags; + int ret; + + raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags); + ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb); + raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags); + return ret; +} +EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier); + +/** + * cpu_pm_enter - CPU low power entry notifier + * + * Notifies listeners that a single CPU is entering a low power state that may + * cause some blocks in the same power domain as the cpu to reset. + * + * Must be called on the affected CPU with interrupts disabled. Platform is + * responsible for ensuring that cpu_pm_enter is not called twice on the same + * CPU before cpu_pm_exit is called. Notified drivers can include VFP + * co-processor, interrupt controller and its PM extensions, local CPU + * timers context save/restore which shouldn't be interrupted. Hence it + * must be called with interrupts disabled. + * + * Return conditions are same as __raw_notifier_call_chain. + */ +int cpu_pm_enter(void) +{ + return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED); +} +EXPORT_SYMBOL_GPL(cpu_pm_enter); + +/** + * cpu_pm_exit - CPU low power exit notifier + * + * Notifies listeners that a single CPU is exiting a low power state that may + * have caused some blocks in the same power domain as the cpu to reset. + * + * Notified drivers can include VFP co-processor, interrupt controller + * and its PM extensions, local CPU timers context save/restore which + * shouldn't be interrupted. Hence it must be called with interrupts disabled. + * + * Return conditions are same as __raw_notifier_call_chain. + */ +int cpu_pm_exit(void) +{ + return cpu_pm_notify(CPU_PM_EXIT); +} +EXPORT_SYMBOL_GPL(cpu_pm_exit); + +/** + * cpu_cluster_pm_enter - CPU cluster low power entry notifier + * + * Notifies listeners that all cpus in a power domain are entering a low power + * state that may cause some blocks in the same power domain to reset. + * + * Must be called after cpu_pm_enter has been called on all cpus in the power + * domain, and before cpu_pm_exit has been called on any cpu in the power + * domain. Notified drivers can include VFP co-processor, interrupt controller + * and its PM extensions, local CPU timers context save/restore which + * shouldn't be interrupted. Hence it must be called with interrupts disabled. + * + * Must be called with interrupts disabled. + * + * Return conditions are same as __raw_notifier_call_chain. + */ +int cpu_cluster_pm_enter(void) +{ + return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED); +} +EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter); + +/** + * cpu_cluster_pm_exit - CPU cluster low power exit notifier + * + * Notifies listeners that all cpus in a power domain are exiting form a + * low power state that may have caused some blocks in the same power domain + * to reset. + * + * Must be called after cpu_cluster_pm_enter has been called for the power + * domain, and before cpu_pm_exit has been called on any cpu in the power + * domain. Notified drivers can include VFP co-processor, interrupt controller + * and its PM extensions, local CPU timers context save/restore which + * shouldn't be interrupted. Hence it must be called with interrupts disabled. + * + * Return conditions are same as __raw_notifier_call_chain. + */ +int cpu_cluster_pm_exit(void) +{ + return cpu_pm_notify(CPU_CLUSTER_PM_EXIT); +} +EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit); + +#ifdef CONFIG_PM +static int cpu_pm_suspend(void) +{ + int ret; + + ret = cpu_pm_enter(); + if (ret) + return ret; + + ret = cpu_cluster_pm_enter(); + return ret; +} + +static void cpu_pm_resume(void) +{ + cpu_cluster_pm_exit(); + cpu_pm_exit(); +} + +static struct syscore_ops cpu_pm_syscore_ops = { + .suspend = cpu_pm_suspend, + .resume = cpu_pm_resume, +}; + +static int cpu_pm_init(void) +{ + register_syscore_ops(&cpu_pm_syscore_ops); + return 0; +} +core_initcall(cpu_pm_init); +#endif |