tree 2c6f4fb221d0166e1f9ba3d7a773ae1a1ab636fd
parent b62cc1e71013d23409aa1cf6e8626922c5d2d815
author Andrew F. Davis <afd@ti.com> 1546543432 -0600
committer Andrew F. Davis <afd@ti.com> 1548097627 -0600

ti: k3: drivers: ti_sci: Add processor shutdown API

This is a pseudo-API command consisting of a wait processor status
command and a set device state command queued back-to-back without
waiting for the System Firmware to ACK either message.

This is needed as the K3 power down specification states the System
Firmware must wait for a processor to be in WFI/WFE before powering
it down. The current implementation of System Firmware does not provide
such a command. Also given that with PSCI the core to be shutdown is the
core that is processing the shutdown request, the core cannot itself wait
for its own WFI/WFE status. To workaround this limitation, we submit
a wait processor status command followed by the actual shutdown command.
The shutdown command will not be processed until the wait command has
finished. In this way we can continue to WFI before the wait command
status has been met or timed-out and the shutdown command is processed.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Acked-by: Nishanth Menon <nm@ti.com>