[Discussion] how to implement external power down for ARM

[arnd@arndb.de (Arnd Bergmann)]

On Wednesday 06 May 2015 14:56:58 Shannon Zhao wrote:
> On 2015/5/5 19:13, Shannon Zhao wrote:
>         gpio-keys {
>                 autorepeat;
>                 #address-cells = <0x1>;
>                 #size-cells = <0x0>;
>                 compatible = "gpio-keys";
> 
>                 poweroff {
>                         gpios = <0x8002 0x3 0x0>;
>                         linux,code = <0x74>;
>                         label = "GPIO Key Poweroff";
>                 };
>         };
> 
> Configure kernel to select GPIO Buttons and Polled GPIO buttons. Use a
> Redhat filesystem "Red Hat Enterprise Linux Server for ARM Development
> Preview release 1.5" which has systemd and systemd-logind. Start VM and
> when it starts well type "system_powerdown" on QEMU monitor, the guest
> goes to poweroff. So this way works.

Ok, very good.

> Note: we must check the /lib/udev/rules.d/70-power-switch.rules in the
> fs and add one following line in it if it doesn't exist.
> 
> SUBSYSTEM=="input", KERNEL=="event*", SUBSYSTEMS=="platform",
> ATTRS{keys}=="116", TAG+="power-switch"
> 
> Then when execute journalctl -u systemd-logind in guest, we can see
> something like below:
> 
> Jan 01 00:01:02 localhost systemd[1]: Starting Login Service...
> Jan 01 00:01:07 localhost systemd[1]: Started Login Service.
> Jan 01 00:01:07 localhost systemd-logind[927]: Watching system buttons
> on /dev/input/event0 (gpio-keys)
> Jan 01 00:01:07 localhost systemd-logind[927]: New seat seat0.
> Jan 01 00:01:25 localhost systemd-logind[927]: New session c1 of user root.
> 
> Visit https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1347776 for
> details.

How about Ubuntu or Debian releases that do not use systemd?

I guess we should check with a Debian Wheezy or Ubuntu Trusty release.
My guess is that it will work fine, but some minor adjustment might
be needed.

	Arnd