停止运行时如何关闭linux电源? [英] How to make linux power off when halt is run?

问题描述

我已经成功使用pm_power_off函数指针使我的自定义Linux板通过i2c调用其电源管理芯片(以关闭电源).

I have successfully used the pm_power_off function pointer to make my custom Linux board call its power management chip over i2c (to turn the power off).

我也希望Linux halt命令也能关闭电源.

I would like the Linux halt command to switch the power off too.

我该如何实现?

machine_halt的(ARM)代码没有类似于machine_power_off的pm_power_off的指针.

The (ARM) code for machine_halt does not have an pointer analogous to machine_power_off's pm_power_off.

arch/arm/kernel/reboot.c:

arch/arm/kernel/reboot.c:

/*
 * Halting simply requires that the secondary CPUs stop performing any
 * activity (executing tasks, handling interrupts). smp_send_stop()
 * achieves this.
 */
void machine_halt(void)
{
    local_irq_disable();
    smp_send_stop();

    local_irq_disable();
    while (1);
}

/*
 * Power-off simply requires that the secondary CPUs stop performing any
 * activity (executing tasks, handling interrupts). smp_send_stop()
 * achieves this. When the system power is turned off, it will take all CPUs
 * with it.
 */
void machine_power_off(void)
{
    local_irq_disable();
    smp_send_stop();

    if (pm_power_off)
        pm_power_off();
}

我显然可以只破解machine_halt，但如果可能的话，我想适当地"做到这一点.

I could obviously just hack machine_halt, but I would like to do this "properly", if possible.

我是否错过了某些内容(可能在用户空间中)，可能导致halt命令执行关闭电源"?

Have I missed something (perhaps in userspace) which could cause a halt command to execute a "power off"?

更新:感谢您的回答和您的所有评论，他们帮助我意识到了实际的问题所在.

Update: Thanks for the answer and all of your comments, they have helped me realise what the actual issue is.

我的问题是:

我有一个输入边，可用于自定义电源管理单元.可以将其视为启动按钮，没有停止或重置功能.我完全可以控制PMU代码(这是一个ATMEGA作为i2c从设备运行).

I have an input edge, available to the custom power management unit. Think of it as a start button, with no stop or reset functionality. I have full control of the PMU code (it's an ATMEGA running as an i2c slave).

1. 如果Linux内核正在运行，我希望忽略边缘.
2. 如果CPU断电，我希望边缘能够打开CPU.
3. 如果Linux内核停止运行，我希望边缘重新设置CPU.

案例1很简单，无所事事.

Case 1 is easy, nothing to do.

情况2很简单，请在驱动程序中定义pm_power_off，以向PMU发送i2c消息.幸运的是，调用pm_power_off时，i2c子系统仍处于工作状态.

Case 2 was easy, define pm_power_off in my driver to send an i2c message to the PMU. Luckily the i2c subsystem is still in a working state when pm_power_off is called.

问题3是问题-我一直在寻找pm_halt进行定义，以向PMU发送i2c消息.

Case 3 is the problem - I was looking for a pm_halt to define, to send an i2c message to the PMU.

也许还有另一种方式，例如0andriy评论?

Perhaps there is another way, as 0andriy comments?

内核中是否有地方以i2c消息以几赫兹的速率向PMU发出信号，除非是halt计算机?

Is there a place in the kernel to keep prodding the PMU with i2c messages at a few Hz, unless the machine is halted?

位于 https://unix.stackexchange.com/a/42576/17288 的答案为:

"**如果启用了ACPI，这些天的停顿足够聪明，可以自动关闭电源.实际上，它们现在在功能上是等效的."

"* These days halt is smart enough to automatically call poweroff if ACPI is enabled. In fact, they are functionally equivalent now."

也许有某种方式可以提供或吸引ACPI-我将不得不仔细阅读.

Perhaps there is some way of providing or hooking into ACPI - I will have to read up on it.

推荐答案

您应使用poweroff命令或halt -p.根据 man 8停止，halt命令(不带参数)不保证关闭计算机电源. 这里:

You should use poweroff command or halt -p. As per man 8 halt, halt command (with no arguments) doesn't guarantee to power off your machine. Reasons are described here:

在ACPI之前使用了

halt(今天将为您关闭电源)*.它将停止系统，然后打印一条消息，提示现在可以关闭电源".那时有物理的开/关开关，而不是现代计算机的组合ACPI控制的电源按钮.

halt was used before ACPI (which today will turn off the power for you)*. It would halt the system and then print a message to the effect of "it's ok to power off now". Back then there were physical on/off switches, rather than the combo ACPI controlled power button of modern computers.

*这几天halt很聪明，如果启用了ACPI，则可以自动关闭电源.实际上，它们现在在功能上是等效的.

*These days halt is smart enough to automatically call poweroff if ACPI is enabled. In fact, they are functionally equivalent now.

从halt工具源代码中可以看到，它发出cmd = RB_POWER_OFF = LINUX_REBOOT_CMD_POWER_OFF> reboot()系统调用.

As you can see from halt tool source code, it issues reboot() system call with cmd = RB_POWER_OFF = LINUX_REBOOT_CMD_POWER_OFF.

在内核中，该系统调用是在此处实现的，并在cmd = LINUX_REBOOT_CMD_POWER_OFF上调用:
   -> kernel_power_off()
   -> machine_power_off()
   -> pm_power_off()

In kernel, that system call is implemented here, and on cmd = LINUX_REBOOT_CMD_POWER_OFF, it calls:
   -> kernel_power_off()
   -> machine_power_off()
   -> pm_power_off()

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