sys/shell: add pm command for power management

[gschorcht]

Contribution description

This PR moves the pm commands from tests/periph_pm' to a shell command module pm_cmd to make them available for embedding in other applications, e.g. for debugging by using

USEMODULE=pm_cmd BOARD=... make -C tests/shell

The test application tests/periph_pm now uses the shell command module instead of defining the pm commands by itself.

Dependent on module pm_layered and feature periph_rtc the following commands are available:

off		turn off
reboot		reboot
set		set power mode
block		block power mode
unblock		unblock power mode
unblock_rtc	temporary unblock power mode

The set, block, unblock commands are available if the platform supports pm_layerd. The unblock_rtc is only available if the platform support pm_layered and feature periph_rtc.

Testing procedure

Compile and flash tests/periph for a board with periph_rtc feature, for example

make BOARD=nucleo-f411re -C tests/periph_pm flash term

and excute the following tests:

• Set mode 1

  > rtc gettime
  2020-03-22 16:30:18
  > rtc setalarm 2020-03-22 16:30:40
  > pm set 1
  CPU will enter power mode 1.
  ...
  > 
  

• Set mode 1

  rtc setalarm 2020-03-22 16:31:50
  > 
  > pm set 0
  CPU will enter power mode 0.
  .main(): This is RIOT! (Version: 2020.04-devel-1400-g5aff3-sys/shell/pm_cmd)
  test_shell.
  >
  

• Unblock mode 1 for 5 seconds

  > pm unblock 1 5
  

• Reboot with pm command

  > pm reboot
  

• Power off pm command

  > pm off
  

Issues/PRs references

[aabadie]

Sorry, duplicate of #11731...

[gschorcht]

@aabadie Sorry, duplicate of #11731

Okay, I didn't realize that, no problem. I just needed the pm command to test PM in other applications and had to copy and paste it over and over again. So I just moved it to a module and thought it was worth sharing it with others. If there is already a PR, this is even better.

[benemorius]

At first glance this looks more mature than #11731 so I'm inclined to abandon it.

@gschorcht could you add a pm show command?

[gschorcht]

@gschorcht could you add a pm show command?

Sure.

[aabadie]

At first glance this looks more mature than #11731 so I'm inclined to abandon it.

Not sure, this PR introduces pm_cmd which I think is not needed (well, there are design decisions that should be further discussed, since pm reboot might now be duplicated in the shell) .
I would rather go with #11731 which is close from being merged (if you address the remaining comments). We can improve it later or eventually @gschorcht can take it over ?

The pm show command is also a nice addition in #11731.

[benemorius]

@aabadie you're right I'm sorry I completely forgot there was a review on that one already. IIRC I addressed the comments and neglected to say anything about it. I'll check on it now.