feat: Implement system power management with Ctrl+Alt+Del and Ctrl+Alt+Backspace

[ionutnechita]

Related with:

(feat: Implement system power management with Ctrl+Alt+Del and Ctrl+Alt+Backspace #18)

[differrari]

Perfect, and sorry again for accidentally closing the PR, I do wanna discuss it first but I don't have a problem leaving it open, and it could've helped in making comments on syntax.
For that, before resubmitting, check the newly added guidelines for things like comments, I prefer the code be self-explanatory without comments which I believe your code (at a quick glance) is. Also some of the functions have repeat functionality, it'd be better to have an extra function, so as to not repeat code if unnecessary. There's also async.h with wait and delay functions, which might help remove some of the for loops.

As for the functionality itself, I'm not familiiar with these features, but I'm assuming this kind of thing is board specific?
I see you have a mailbox call for it for the pi, and also a qemu option, which relies on semihosting, but I'm not familiar with that option or how it helps and what it implies.

[ionutnechita]

Hello.

I tried to make the code as clean as possible. But there are still a few things to rewrite to make it look good. I liked the idea of REDACTED OS. So I brought this power state / control feature to your project.
For the mailbox and semihosting part, I tried to emulate as close to the host as possible anticipating the arm64 platform; but to also be able to debug on signals.
If I have time next period, I'll rewrite this PR a bit.
I am also busy with development and integration of code and patches on a personal realtime Linux tree.
We'll keep in touch and I'll continue to follow you on YouTube. :)

[differrari]

Thank you so much for contributing to the project again, please do resubmit the PR if you have time, I'd love to include the functionality

[ionutnechita]

PR: #32

To be refactor.