Public Version
www.ti.com
L4 Interconnects
9.3.2.1.4 Power Management
9.3.2.1.4.1 Module Power-Saving
The L4 interconnect automatically performs internal clock autogating to reduce power consumption.
Though not recommended, it is possible to deactivate clock autogating by writing 1 to the
CLOCK_GATE_DISABLE bit
[24] of each L4 interconnect. Clock
autogating is enabled by default.
9.3.2.1.4.2 System Power Management and Wakeup
As part of the system-wide power-management scheme, the L4 interconnect enters an idle state at the
request of the PRCM module (for more information, see Power, Reset, and Clock Management). The L4
interconnect is always in smart-idle mode; that is, it goes into idle state after receiving the request from the
PRCM module once all the transfer requests are complete. This functionality is handled by hardware. The
L4 interconnect sends an acknowledge signal back to the PRCM module when it enters idle state.
9.3.3 L4 Interconnects Functional Description
9.3.3.1
L4-Interconnects Initiator Identification
In the device interconnect, a ConnID is an initiator module identifier. The L4 interconnect uses the same
ConnID as L3.
9.3.3.2
Endianness Management
Both L4 interconnects are little-endian only. Any initiator accessing the L4 interconnect module must
consider byte ordering and perform a conversion, if necessary.
9.3.3.3
L4 Protection and Firewalls
9.3.3.3.1 Protection Mechanism
The following two parameters are used to set up access permission because of the large address spaces
and the number of peripherals connected to the L4 interconnects:
•
Programmable groups for initiators:
–
8 protection groups for the L4-Core interconnect
–
8 protection groups for the L4-Per interconnect
–
6 protection groups for the L4-Emu interconnect
•
Each segment is divided into regions of 2K bytes:
–
100 regions for the L4-Core interconnect
–
43 regions for the L4-Per interconnect
–
26 regions for the L4-Emu interconnect
NOTE:
Regions and segments are present for the L4-Wakeup interconnect but cannot be
programmed. The L4-Wakeup protection is done through the L4-Core and L4-Emu
interconnects.
A protection group is a group of targets that have the same protection settings. Initiator access is defined
by CONNID_BIT_VECTOR field L4_AP_PROT_GROUP_k_L[15:0]. The initiators have the same access
permission to all regions in this group.
A region is programmed to allow access to a unique selectable protection group by using
PROT_GROUP_ID field
[22:20].
2061
SWPU177N – December 2009 – Revised November 2010
Interconnect
Copyright © 2009–2010, Texas Instruments Incorporated
