firmware: ti_sci: Add system suspend and resume call

Introduce system suspend call that enables the ti_sci driver to support
low power mode when the user space issues a suspend to mem.

The following power management operations defined in the TISCI
Low Power Mode API [1] are implemented to support suspend and resume:

1) TISCI_MSG_PREPARE_SLEEP
Prepare the SOC for entering into a low power mode and
provide details to firmware about the state being entered.

2) TISCI_MSG_SET_IO_ISOLATION
Control the IO isolation for Low Power Mode.

Also, write a ti_sci_prepare_system_suspend call to be used in the driver
suspend handler to allow the system to identify the low power mode being
entered and if necessary, send TISCI_MSG_PREPARE_SLEEP with information
about the mode being entered.

Sysfw version >= 10.00.04 support LPM_DM_MANAGED capability [2], where
Device Mgr firmware now manages which low power mode is chosen. Going
forward, this is the default configuration supported for TI AM62 family
of devices. The state chosen by the DM can be influenced by sending
constraints using the new LPM constraint APIs.

In case the firmware does not support LPM_DM_MANAGED mode, the mode
selection logic can be extended as needed. If no suspend-to-RAM modes
are supported, return without taking any action.

We're using "pm_suspend_target_state" to map the kernel's target suspend
state to SysFW low power mode. Make sure this is available only when
CONFIG_SUSPEND is enabled.

Suspend has to be split into two parts, ti_sci_suspend() will send
the prepare sleep message to prepare suspend. ti_sci_suspend_noirq()
sets IO isolation which needs to be done as late as possible to avoid
any issues. On resume this has to be done as early as possible.

[1] https://software-dl.ti.com/tisci/esd/latest/2_tisci_msgs/pm/lpm.html



Co-developed-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Georgi Vlaev <g-vlaev@ti.com>
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Vibhore Vardhan <vibhore@ti.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Tested-by: Roger Quadros <rogerq@kernel.org>
Link: https://lore.kernel.org/r/20241007-tisci-syssuspendresume-v13-3-ed54cd659a49@baylibre.com


Signed-off-by: Nishanth Menon <nm@ti.com>