[RFC] how to implement suspend to ram for arm64?

[Jisheng Zhang]

Hi list,

we need the suspend to ram feature on arm64. And I think the fundamental code
is ready, for example  __cpu_suspend() etc.

However, there are several issues need to be resolved...

1. where to put platform_suspend_ops implementation? drivers/power?

2. If the "put ddr to self refresh" code must be in EL3 or secure EL1, how
linux tell the firmware to trigger it? extend PSCI or use the context_id
of PSCI CPU_SUSPEND function?

3. where to put the cod of invoke suspend_to_ram psci call?

Thanks in advance,
Jisheng