Linux 电源管理在ARM上的实现原理（4） return, error, Linux, 电源

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if (dev->bus) {
   if(dev->bus->pm) {
      pm_dev_dbg(dev, state, "");
      error = pm_op(dev, dev->bus->pm,state);
   } else if(dev->bus->suspend) {
      pm_dev_dbg(dev, state, "legacy ");
      error = dev->bus->suspend(dev,state);
      suspend_report_result(dev->bus->suspend,error);
   }
  }
End:
up(&dev->sem);
  return error;
}

4.2.2 进入阶段

回到suspend_devices_and_enter（）再看suspend_enter(state)函数
static int suspend_enter(suspend_state_t state)
{
  int error;
//调用体系结构相关的函数, 这是在系统初始化的时候注册的
  if (suspend_ops->prepare) {
     error= suspend_ops->prepare();
    if (error)
       return error;
  }

  error = device_power_down(PMSG_SUSPEND);
  if (error) {
     printk(KERN_ERR"PM: Some devices failed to power down\n");
    goto Platfrom_finish;
  }
  if (suspend_ops->prepare_late){
    error = suspend_ops->prepare_late();
    if (error)
       goto Power_up_devices;
  }
  if (suspend_test(TEST_PLATFORM))
    goto Platform_wake;
  error = disable_nonboot_cpus();
  if (error ||suspend_test(TEST_CPUS))
     gotoEnable_cpus;
  arch_suspend_disable_irqs();
  BUG_ON(!irqs_disabled());
  error = sysdev_suspend(PMSG_SUSPEND);
  if (!error) {
    if (!suspend_test(TEST_CORE))
//调用体系结构相关的函数, 这是在系统初始化的时候注册的
        error = suspend_ops->enter(state);
    sysdev_resume();
    }
  arch_suspend_enable_irqs();
  BUG_ON(irqs_disabled());

Enable_cpus:
  enable_nonboot_cpus();
Platform_wake:
  if (suspend_ops->wake)
    suspend_ops->wake();
Power_up_devices:
  device_power_up(PMSG_RESUME);
Platfrom_finish:
  if (suspend_ops->finish)
//调用体系结构相关的函数, 这是在系统初始化的时候注册的
    suspend_ops->finish();
  return error;
}
这个suspend_ops就是在体系结构初始化的时候注册进来的,
接着看arch/arm/plat-s3c/pm.c
int __init s3c_pm_init(void)
{
  printk("S3C Power Management,Copyright 2004 Simtec Electronics\n");
suspend_set_ops(&s3c_pm_ops);
  return 0;
}

static struct platform_suspend_ops s3c_pm_ops = {
  .enter = s3c_pm_enter,
  .prepare = s3c_pm_prepare,
  .finish = s3c_pm_finish,
  .valid =suspend_valid_only_mem,
};