Problem Statement:
Not all Zephyr kernel drivers provide the same interfaces.

Why this is a problem:
-----------------------------
The Zephyr kernel currently has devices that are essential for core OS
functions (such as APICs and timers), but provide no public API means
for accessing them. Without any consistent method to access device
drivers on the platform, it becomes very difficult to achieve power
targets.

What should be done:
-----------------------------
1) Each native Zephyr kernel driver and shim driver (such as QMSI) shall
support:

a) uint32_t suspend() - routine that will move any required device state
data
to RAM* with the following valid return values:
- DEV_OK
- DEV_BUSY
- DEV_FAIL

b) uint32_t resume() - routine that will retrieve any device state data
from
RAM* with the following valid return values:

- DEV_OK
- DEV_FAIL

2) Provide a name recognized by the device_get_binding() function, this
includes what are currently thought to be drivers such as timers,
IOAPIC, and LOAPIC.

*The power management process is not expected to power down system RAM
(it will most likely stay in selective suspend).

The size of the device data is dependent upon an individual device, and
therefore the system integrator must be wary of the number of devices
being utilized.

Device suspend flow:
Device Drivers at suspend shall:
- Device state shall be saved to memory and maintained across a PM event
- Turning off the device clock
- Return appropriate error code

Device resume flow:
Device Drivers at resume shall:
- Restore to state saved in memory
- Turn on the device clock
- Return appropriate error code

Device domain experts will be needed to implement the proper methods for
suspending and resuming each device.