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Services Power Management Unit
Copyright © 12/13/06 Marvell
CONFIDENTIAL
Doc. No. MV-TBD-00 Rev. A
December 13, 2006
Document Classification: Proprietary Information
Page 205
Not approved by Document Control. For review only.
8.7.2.3.2
Preparation for S2 State
The sequence for entering S2 state is:
4. The core software writes the D3 unit-retention bits in the “Application Subsystem D3 Configuration register
(AD3R)” for any units that have to retain state while the BPMU is in D3 state.
5. The core software must configure the external memory controller to ensure SDRAM contents are
maintained during S2 state.
6. The core software writes the Wake-up registers to enable the application-subsystem wake-up sources for D3
mode:
•
“Application Subsystem Wake-Up from D3 register (AD3ER)”
7. The core software writes the Wake-up registers to enable the MPMU and BPMU wake-up sources for S2
and D3 mode:
•
See
“Power Manager Wake-Up Enable Register (PWER)”
•
See Chapter 9, “Application Subsystem Wake-Up from D3 Enable Register (AD3ER)”
8. The core software writes to the core PWRMODE register (CP14 Register 7) to initiate the MPMU S2 entry.
Note:
When the PWRMODE register (CP14 Register 7) is written to initiate MPMU S2 entry, the
BPMU is transitioned automatically to D3 state prior to MPMU S2 entry. For the MPMU to exit
S2 due to a S2 wake-up event, the wake-up events must be enabled in both the
Wake-Up Enable Register (PWER)”
and Chapter 9, “Application Subsystem Wake-Up from D3
Enable Register (AD3ER)”.
8.7.2.3.3
Entering S2 State
Entry into S2 state is initiated by setting the mode bits in the core PWRMODE Register (CP14 Register 7) to S2
state.
When the bits are written, the BPMU transitions the application subsystem to D3 mode and the MPMU
transitions the rest of the processor architecture to S2 state. Refer to the “Slave
Power Manager Unit” for the
BPMU sequence to enter and exit D3 mode.The MPMU begins transition to S2 state after the BPMU has entered
D3. To complete S2 state entry, the MPMU completes the following:
1. The MPMU disables the core and system PLLs.
2. The MPMU disables the processor oscillator.
3. The MPMU asserts nRESET_OUT if SL_ROD is clear in the
“Power Management Unit General
Configuration Register (PCFR)”
. The BPMU asserts reset to all units not selected by the D3 unit-retention
bits.
4. The MPMU negates PWR_EN, and PWR_I2C sends I
2
C commands to disable the VCC_APPS power
supply. Enabling and disabling the voltage-change sequencer which controls the automatic PWR_I2C
commands to the VCC_APPS power supply is accomplished with the PVE bit in
Voltage Change Control Register (PVCR)”
. The VCC_SRAM supply is disabled in S2 mode when all
SRAMs are programmed off. If PVCR[PVE] is cleared to 0, no voltage-change sequence commands are
sent. If PVCR[PVE] is set to 1, the voltage-change sequence consists of the following which are
automatically sent by the PWR_I2C unit: