AArch64 has support for PSCI. This is especially useful for SMP because
PSCI is used to power on the secordary cores.
When the PSCI driver was introduced in Zephyr it was designed to rely on
a very PSCI-centric subsystem / interface.
There are two kinds of problems with this choice:
1. PSCI is only defined for the non-secure world and it is designed to
boot CPU cores into non-secure state (that means that PSCI is only
supposed to work if Zephyr is running in non-secure state)
2. There can be other ways or standards used to start / stop a core
different from PSCI
This patch is trying to fix the original wrong assumption by making the
interface / subsystem a generic one, called 'pm_cpu_ops', and using PSCI
only as an actual driver that is a user of this new interface /
subsystem.
For now the new subsystem is only exposing two methods: cpu_on and
cpu_off, others will probably follow according to the needs.
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
Firmware implementing the PSCI functions described in ARM document
number ARM DEN 0022A ("Power State Coordination Interface System
Software on ARM processors") can be used by Zephyr to initiate various
CPU-centric power operations.
It is needed for virtualization, it is used to coordinate OSes and
hypervisors and it provides the functions used for SMP bring-up such as
CPU_ON and CPU_OFF.
A new PSCI driver is introduced to setup a proper subsystem used to
communicate with the PSCI firmware, implementing the basic operations:
get_version, cpu_on, cpu_off and affinity_info.
The current implementation only supports PSCI 0.2 and PSCI 1.0
The PSCI conduit (SMC or HVC) is setup reading the corresponding
property in the DTS node.
Signed-off-by: Carlo Caione <ccaione@baylibre.com>
