pmdomain: thead: Add power-domain driver for TH1520

The T-Head TH1520 SoC contains multiple power islands that can be
programmatically turned on and off using the AON (Always-On) protocol
and a hard

pmdomain: thead: Add power-domain driver for TH1520

The T-Head TH1520 SoC contains multiple power islands that can be
programmatically turned on and off using the AON (Always-On) protocol
and a hardware mailbox [1]. The relevant mailbox driver has already been
merged into the mainline kernel in commit 5d4d263e1c6b ("mailbox:
Introduce support for T-head TH1520 Mailbox driver");

Introduce a power-domain driver for the TH1520 SoC, which is using AON
firmware protocol to communicate with E902 core through the hardware
mailbox. This way it can send power on/off commands to the E902 core.

The interaction with AUDIO power island e.g trying to turn it OFF proved
to crash the firmware running on the E902 core. Introduce the workaround
to disable interacting with the power island.

[1]
Link: https://openbeagle.org/beaglev-ahead/beaglev-ahead/-/blob/main/docs/TH1520%20System%20User%20Manual.pdf

Signed-off-by: Michal Wilczynski <[email protected]>
Acked-by: Drew Fustini <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ulf Hansson <[email protected]>

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