Public Version
PRCM Functional Description
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3.5.3.7
Internal Clock Controls
This section describes the software and hardware controls of the internal source clocks.
through
list the clock controls. The Source selection/division column lists the PRCM register
bits that select or divide the clocks. The Software control column lists the PRCM register bits that
enable/disable the clocks. The Hardware control column lists the hardware conditions required to
effectively gate the clocks.
In the Hardware control column, the boxes labeled CL, GS, GC, and HC indicate specific information
about the hardware clock controls:
•
CL (combinational logic): The functional or interface clock is required by more than one module across
more than one power domain. The gating control is the OR combination of all the domain clock
requests. If any module of this clock domain requests the clock, the clock is not gated.
•
GS (gating selection): The clock is selectable among several possible source clocks for a module. The
gating control depends on the software programming of the CM_CLKSEL_<domain_name> type of
register. The clock request of the module or domain must be set by the CM_CLKSEL bit.
•
GC (gating control): The functional/interface clock is required by a single module across the power
domain. The gating control depends only on the software programming of the FCLKEN/ICLKEN bit.
For the interface clock, the enable bit is effective only if autoidle mode is not used. If autoidle mode is
used, the gating control also depends on the state of the power domain.
•
HC (hardware control): A specific rule not covered by CL, GS, or GC.
NOTE:
Because the PRCM module must receive hardware acknowledgment from the different
modules before it can gate the clock, the clock is not gated immediately after the software
requests clock-gating conditions.
3.5.3.7.1 PRM Source-Clock Controls
shows the common source-clock controls for the PRM.
334
Power, Reset, and Clock Management
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated
