The OpenRISC architecture has the Power Management Register (PMR)
special purpose register to manage cpu power states. The interesting
modes are:
* Doze Mode (DME) - Stop cpu except timer & pic - wake on interrupt
* Sleep Mode (SME) - Stop cpu and all units - wake on interrupt
* Suspend Model (SUME) - Stop cpu and all units - wake on reset
The linux kernel will set DME when idle.
This patch implements the PMR SPR and halts the qemu cpu when there is a
change to DME or SME. This means that openrisc qemu in no longer peggs
a host cpu at 100%.
In order for this to work we need to kick the CPU when timers are
expired. Update the cpu timer to kick the cpu upon each timer event.
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Stafford Horne <shorne@gmail.com>
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