cregit-Linux how code gets into the kernel

Release 4.16 kernel/cpu_pm.c

Directory: kernel
/*
 * Copyright (C) 2011 Google, Inc.
 *
 * Author:
 *      Colin Cross <ccross@android.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#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>

static ATOMIC_NOTIFIER_HEAD(cpu_pm_notifier_chain);


static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls) { int ret; /* * __atomic_notifier_call_chain has a RCU read critical section, which * could be disfunctional in cpu idle. Copy RCU_NONIDLE code to let * RCU know this. */ rcu_irq_enter_irqson(); ret = __atomic_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL, nr_to_call, nr_calls); rcu_irq_exit_irqson(); return notifier_to_errno(ret); }

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Colin Cross4183.67%150.00%
Alex Shi816.33%150.00%
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/** * 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 may sleep, and has the same return conditions as * raw_notifier_chain_register. */
int cpu_pm_register_notifier(struct notifier_block *nb) { return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb); }

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Colin Cross1789.47%150.00%
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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 may sleep, and has the same return conditions as * raw_notifier_chain_unregister. */
int cpu_pm_unregister_notifier(struct notifier_block *nb) { return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb); }

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Colin Cross1789.47%150.00%
Alex Shi210.53%150.00%
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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) { int nr_calls; int ret = 0; ret = cpu_pm_notify(CPU_PM_ENTER, -1, &nr_calls); if (ret) /* * Inform listeners (nr_calls - 1) about failure of CPU PM * PM entry who are notified earlier to prepare for it. */ cpu_pm_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL); return ret; }

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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, -1, NULL); }

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Colin Cross1794.44%150.00%
Alex Shi15.56%150.00%
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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) { int nr_calls; int ret = 0; ret = cpu_pm_notify(CPU_CLUSTER_PM_ENTER, -1, &nr_calls); if (ret) /* * Inform listeners (nr_calls - 1) about failure of CPU cluster * PM entry who are notified earlier to prepare for it. */ cpu_pm_notify(CPU_CLUSTER_PM_ENTER_FAILED, nr_calls - 1, NULL); return ret; }

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Colin Cross47100.00%1100.00%
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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, -1, NULL); }

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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; }

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static void cpu_pm_resume(void) { cpu_cluster_pm_exit(); cpu_pm_exit(); }

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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; }

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core_initcall(cpu_pm_init); #endif

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Directory: kernel
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