MOTOROLA
Appendix A. Power Management
A-7
their fast recovery time; sleep and suspend modes are intended for longer periods of power
savings with the PLL and SYSCLK off.
A.2.3 PCI Address Bus Decoding
PCI address bus decoding is enabled while the MPC106 is in the doze or nap mode. A PCI
transaction to system memory awakens the MPC106 from the doze or nap power saving
mode.
After servicing the PCI transaction, the MPC106 returns to the previous power saving mode
(doze or nap) if there are no additional PCI bus service requests. In systems using a 603,
the L1 cache should be flushed prior to entering the nap mode. Systems designed using the
601 or 604 are not required to flush their L1 caches prior to entering the nap mode.
A.2.4 PCI Bus Special-Cycle Operations
Before the MPC106 enters the nap or sleep mode, it will broadcast the halt or shutdown
message over the PCI bus by means of special bus cycle. See Section 7.4.6.2,
“Special-Cycle Transactions,” for a description of PCI special-cycle operations.
In nap mode, if PMCR[NO_NAP_MSG] is cleared to 0, the MPC106 broadcasts the halt
message over the PCI bus. If PMCR[NO_NAP_MSG] is set to 1, the MPC106 does not
broadcast any message to the PCI bus.
In sleep mode, if PMCR[NO_SLEEP_MSG] is cleared to 0, the MPC106 broadcasts either
the halt or shutdown message over the PCI bus depending on whether
PMCR[SLEEP_MSG_TYPE] is cleared or set. If PMCR[NO_SLEEP_MSG] is set to 1,
the MPC106 does not broadcast any message to the PCI bus and the configuration of
PMCR[SLEEP_MSG_TYPE] is ignored.
A.2.5 Processor Bus Request Monitoring
In doze, nap, and sleep modes, the MPC106 monitors the BR0 signal. When BR0 is
asserted, (for example, due to the processor’s time base interrupt service routine), the
MPC106 exits its power saving mode and returns to the full-on mode to service the request.
Additionally, in a multiprocessor system, BR[1–3] can be used to awaken the MPC106. In
nap or sleep mode, the assertion of BR1, BR2, or BR3 is treated as a wake up event if
PMCR[BR1_WAKE] is set to 1. In doze mode, it is unconditional, and does not depend
upon the condition of the bit in PMCR[BR1_WAKE].
A.2.6 Memory Refresh Operations in Sleep/Suspend Mode
In sleep or suspend mode, all functional units, including the system memory refresh logic,
will not be operating. The system memory contents can be maintained either by enabling
the memory’s self-refresh mode or by having the system software copy all the memory
contents to a hard disk before the MPC106 enters the sleep or suspend mode. However, if
the memory does not have self-refresh capability or the system software has not copied the