ARM Cortex-A8 MPU Subsystem
Table 3-6. MPU Subsystem Operation Power Modes
Mode
MPU and ARM Core
ARM L2 RAM
NEON INTC
Device Core and
APB/ATB Debug
Logic
ETM
1
Active
Active
Active
Active
Disabled or enabled
2
Active
Active
OFF
Active
Disabled or enabled
3
Active
RET
Active
Active
Disabled or enabled
4
Active
RET
OFF
Active
Disabled or enabled
5
Active
OFF
Active
Active
Disabled or enabled
6
Active
OFF
OFF
Active
Disabled or enabled
7
OFF
RET
OFF
OFF
Disabled or enabled
8
Standby
Active
Standby
Active
Disabled or enabled
9
Standby
Active
OFF
Active
Disabled or enabled
10
Standby
RET
Standby
Active
Disabled or enabled
11
Standby
RET
OFF
Active
Disabled or enabled
12
Standby
OFF
Standby
Active
Disabled or enabled
13
Standby
OFF
OFF
Active
Disabled or enabled
14
OFF
OFF
OFF
OFF
Disabled or enabled
3.1.7 ARM Programming Model
For detailed descriptions of registers used for MPU configuration, see
, Power, Reset, and Clock
Management (PRCM).
3.1.7.1
Clock Control
For clock configuration settings, see
, Power, Reset, and Clock Management (PRCM).
3.1.7.2
MPU Power Mode Transitions
The following subsections describe transitions of different power modes for MPU power domain:
•
Basic power on reset
•
MPU into standby mode
•
MPU out of standby mode
•
MPU power on from a powered off state
3.1.7.2.1 Basic Power-On Reset
The power-on reset follows the following sequence of operation and is applicable to initial power-up and
wakeup from device off mode:
Reset the INTC (CORE_RST) and the MPU subsystem modules (MPU_RST). The clocks must be
active during the MPU reset and CORE reset.
3.1.7.2.2 MPU Into Standby Mode
The MPU into standby mode follows the following sequence of operation and is applicable to initial power-
up and wakeup from device Off mode.
1. The ARM core initiates entering into standby via software only (CP15 - WFI).
2. MPU modules requested internally of MPU subsystem to enter idle, after ARM core standby detected.
3. MPU is in standby output asserted for PRCM (all outputs guaranteed to be at reset values).
4. PRCM can now request INTC to enter into idle mode. Acknowledge from INTC goes to PRCM.
NOTE:
The INTC SWAKEUP output is a pure hardware signal to PRCM for the status of its IDLE
request and IDLE acknowledge handshake.
174
ARM MPU Subsystem
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated