Base Linux RC5.0
echo mem > /sys/power/state
Suspend Resume
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call notifiers Turn On Power
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freeze tasks System core online
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devices suspend Nonboot cpu online
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.prepare Devices Resume
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.suspend .resume_noirq
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.suspend_late .resume_early
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.suspend_noir .resume
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nonboot cpu offline .comnplete
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system core offline thaw tasks
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turn off power call notifiers
autosleep_store /*节点调用的入口函数*/
decode_state /*解析对用state, pm_state的初始化在pm_state_init（pm init完成）*/
pm_autosleep_set_state
__pm_stay_awake(autosleep_ws);
__pm_relax(autosleep_ws);
pm_wakep_autosleep_enabled
pm_suspend （state < PM_SUSPEND_MAX） /*Externally visible function for suspending the system*/
enter_state /*Do common work needed to enter system sleep state*/
state_store
pm_autosleep_lock
pm_autosleep_state() > PM_SUSPEND_ON /*如果进入到suspend流程，返还出去*/
decode_state /*解析对用state, pm_state的初始化在pm_state_init（pm init完成）*/
if (state < PM_SUSPEND_MAX) {
if (state == PM_SUSPEND_MEM)
state = mem_sleep_current; /*mem_sleep_store 函数初始化 mem sleep current的值*/
error = pm_suspend(state); /*Externally visible function for suspending the system*/
enter_state() /*Do common work needed to enter system sleep state*/
if (state == PM_SUSPEND_TO_IDLE)
s2idle_begin(); /*s2idle_state = S2IDLE_STATE_NONE*/
pm_suspend_clear_flags /*设置pm_suspend_global_flags = 0*/
suspend_prepare() /*Prepare for entering system sleep state*/
pm_prepare_console() /*切换 控制台打印口*/
__pm_notifier_call_chain() /*运行suspend的notifylist*/
suspend_freeze_processes()
freeze_processes /*冻结用户进程， 失败则thaw_processes解冻进程*/
freeze_kernel_threads /*冻结内核进程吗，失败则thaw_processes解冻进*/
dpm_save_failed_step() /*what to do????*/
error go out:
__pm_notifier_call_chain /*notify PM_POST_SUSPEND*/
pm_restore_console /*恢复控制台*/
suspend_test() /*调试使用的api*/
suspend_devices_and_enter() /*设备驱动休眠与进系统休眠*/
sleep_state_supported() /*判断是否支持*/
platform_suspend_begin()
s2idle_ops->begin()
suspend_ops->begin(state) /*suspend_set_ops(&psci_suspend_ops); psci 没有begin这个api，所以return*/
suspend_console() /*Suspending console(s) (use no_console_suspend to debug)*/
suspend_test_start() /** what to do???/
dpm_suspend_start()
dpm_prepare()
wait_for_device_probe() /*清理workqueue, 等待wq完成，同步域中的所有异步函数*/
device_block_probing() /*sync with probes to avoid races*/
device_prepare() /*调用devices pm ops.prepare*/
dpm_suspend()
devfreq_suspend()
cpufreq_suspend()
device_suspend（)
/*dpm_prepared_list），转移到dpm_suspended_list*/
async_synchronize_full()
suspend_enter()
platform_suspend_prepare() /*suspend_ops->prepare*/
dpm_suspend_late() /*与dpm suspend 差别, 父节点的devices suspend, suspend late suspend设备*/
platform_suspend_prepare_late() /*s2idle_ops->prepare()*/
s2idle_loop /*state = id or test level RETURN*/
dpm_suspend_noirq() /*要disable irq的设备suspend,noirq，是通过禁止所有的中断线的形式，而不是通过关全局中断的方式*/
platform_suspend_prepare_noirq()
/*suspend_ops->prepare_late(), suspend_ops的prepare_late回调, 通知平台代码，以便让其在最后关头，再做一些处理, 失败的话，需要跳至Platform_wake处,
如果是suspend to freeze，执行相应的操作，包括冻结进程、suspended devices（参数为PM_SUSPEND_FREEZE）、cpu进入idle
如果有任何事件使CPU从idle状态退出，跳至Platform_wake处，执行wake操作*/
disable_nonboot_cpus() /*offline 非boot cpu, 调用cpudown的接口*/
arch_suspend_disable_irqs() /*local_irq_disable*/
syscore_suspend()
pm_wakeup_pending /*检查wakeup状态， return error*/ /*用pm_wakeup_pending检查一下，这段时间内，是否有唤醒事件发生，如果有就要终止suspend*/
ops->suspend /*syscore_ops_list 上的suspend调用，exp: cpufreq_stop_governor*/
pm_wakeup_pending /*再次检查wakeup状态*/
suspend_ops->enter(state) /*调用到psci接口中*/
out path:
syscore_resume
arch_suspend_enable_irqs
enable_nonboot_cpus
platform_resume_noirq
dpm_resume_noirq
platform_resume_early
dpm_resume_early
platform_resume_finish
} else if (state == PM_SUSPEND_MAX) {
error = hibernate();
} else {
error = -EINVAL;
}