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Slave Power Management Unit
Copyright © 12/13/06 Marvell
CONFIDENTIAL
Doc. No. MV-TBD-00 Rev. A
December 13, 2006
Document Classification: Proprietary Information
Page 255
Not approved by Document Control. For review only.
Exiting D4 State
D4 state exits to D0 state with the assertion of any of the following wake-up events:
•
Assertion of any enabled S3 state wake-up event selected in the Power Manager Wake-Up Enable register to
the MPMU.
Exit from D4 state is initiated by the MPMU. The following occurs after the assertion of a S3 wake-up event:
•
The MPMU asserts SYS_EN. The external regulator must respond SYS_EN by enabling the high-voltage
power supplies.
•
The MPMU waits the number of timekeeping oscillator cycles specified by the SYS_DEL bits in the Power
Management Unit General Configuration register (PCFR) if PCFR[SWDD] is clear before continuing the
exit sequence. If PCFR[SWDD] is set, the MPMU exits the SYS_DEL delay count when all the supply
voltages are detected and continues the exit sequence.
•
The MPMU negates the BPMU reset.
•
PWR_EN is asserts and the PWR_I
2
C controller in the services unit sends PWR_I2C commands to the
external regulator to control and enable the VCC_APPS and VCC_SRAM power supplies.
•
The MPMU waits the number of timekeeping oscillator cycles specified by the PWR_DEL bits in the Power
Management Unit General Configuration register (PCFR) if PCFR[SWDD] is clear before continuing the
wake-up sequence. If PCFR[SWDD] is set, the MPMU exits the PWR_DEL delay count when VCC_APPS
and VCC_SRAM voltages are detected and continues the wake-up sequence.
•
The MPMU enables the processor 13 MHz oscillator.
•
The ring oscillator is enabled and used as a temporary clock source for the core and application subsystem
peripherals if PCCE bit in
Section 7.4.1, “Application Subsystem Clock Configuration Register (ACCR)”
is
set.
•
The core PLL is enabled and reprogrammed with the corresponding values in the
“Application Subsystem Clock Configuration Register (ACCR)”
. The system PLL is enabled.
•
Clocks are restarted for units selected by the CKEN bits in the D0CKEN register, refer to
Mode Clock Enable Register A (D0CKEN_A)”
and
Section 7.4.5, “D0 Mode Clock Enable Register B
.
•
The nRESET_OUT pin if asserted is de-asserted, indicating the core is about to perform a fetch from the
reset-vector location. The application subsystem internal resets are negated.
•
The state configuration is cleared in the
Section 4.5.16, “Core PWRMODE Register (CP14 Register 7)”
•
The core begins a normal boot sequence
•
The DDR SDRAM must be brought out of self-refresh mode, which requires the DDR SDRAM controller to
be transitioned to its idle state. See the Memory Controller section for details on configuring the DDR
SDRAM interface.
Normal boot-up sequencing begins, with all units in the application subsystem beginning with their predefined
reset conditions. The core software must examine the
“Application Subsystem Reset Status Register (ARSR)”
to
determine the reset source was a low-power mode exit reset. Finally, if the PSPR in the MPMU was used for
saving any general processor state during S3 state, the state can be recovered.