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SCM Integration
13.3.1.4 Power Management
13.3.1.4.1 System Power Management
The PRCM module can require the SCM to be idled to save power. The SCM enters idle mode through
the CONTROL.
[4:3] IDLEMODE bit field.
The PRCM module requests idle mode, and the SCM always accepts an idle command. Idle mode can be
configured to either force-idle or smart-idle mode.3
When the SCM is in force-idle mode (IDLEMODE bits CONTROL.
[4:3] = 0b00)
and it receives an idle request from the PRCM module (PRCM.CM_ICLKEN1_CORE[6] set to 0 or
PRCM.CM_AUTOIDLE1_CORE[6] set to 1 and the L4-Core interface clock idle transitions), the SCM
waits unconditionally for active system clock gating by the PRCM module. Active system clock gating
occurs only when all peripherals supplied by the same L4-Core interface clock domain are also ready for
idle.
In smart-idle mode (IDLEMODE bits CONTROL.
[4:3] = 0b10), an idle command
is accepted only when the save mechanism completes.
In idle mode (when the PRCM module has gated the interface clock), the SCM is not active and the
interface clock paths are gated.
NOTE:
The PRCM.CM_IDLEST1_CORE[6] ST_OMAPCTRL bit (0b0 = active, 0b1 = idle) can
check the SCM idle state.
The SCM idle mode is a function of the PRCM.CM_ICLKEN1_CORE[6] EN_OMAPCTRL bit
configuration and can be controlled automatically with hardware, depending on the
PRCM.CM_AUTOIDLE1_CORE[6] AUTO_OMAPCTRL bit configuration.
13.3.1.4.2 Module Power Saving
An internal interface clock-gating feature provides SCM local power management. The clock for the logic
within the module can be gated when there is no access to the module according to the
CONTROL.
[0] AUTOIDLE bit. Otherwise, this logic is free-running on the
interface clock CORE_L4_ICLK.
The L4-Core interface clock (CORE_L4_ICLK) is also used to synchronize and resample module inputs.
The clock for those functions must always be free-running. Therefore, it is not gated.
The wake-up control module is clocked only by a local wake-up interface clock from the core control
module. The wake-up interface clock (WKUP_ICLK) uses the L4-Core interface clock (CORE_L4_ICLK)
divided by 4 or 2 to reduce power consumption according to the
CONTROL.
[2] WKUPCTRLCLOCKDIV bit (0 = divided by 4; 1 = divided by
2).
shows the SCM internal clock implementation.
2441
SWPU177N – December 2009 – Revised November 2010
System Control Module
Copyright © 2009–2010, Texas Instruments Incorporated