Table 3-91 Instruction Tcm Non-Secure Control Access Register Bit Functions; Table 3-92 Effects Of Ns Items For Instruction Tcm Operation; Figure 3-53 Instruction Tcm Non-Secure Control Access Register Format - ARM ARM1176JZF-S Technical Reference Manual

Bits Field name
[31:1] -
[0] NS access
ARM DDI 0301H
ID012310
The Instruction TCM Non-secure Control Access Register is:
• in CP15 c9
• a 32-bit read/write register in the Secure world only
• accessible in privileged modes only.
If the processor is configured to have 2 Instruction TCMs, each TCM has a separate Instruction
TCM Non-secure Control Access Register. The TCM Selection Register determines the register
in use.
Figure 3-53 shows the bit arrangement for the Instruction TCM Non-secure Control Access
Register.
31

Figure 3-53 Instruction TCM Non-secure Control Access Register format

Table 3-91 lists how the bit values correspond with the register functions.

Table 3-91 Instruction TCM Non-secure Control Access Register bit functions

Function
UNP/SBZ.
Makes Instruction TCM invisible to the Non-secure world and makes TCM data Secure.
0 = Instruction TCM Region Register only accessible in the Secure world. Instruction TCM only
visible in the Secure world and only when the NS Attribute in the page table is 0. The reset value
is 0.
1 = Instruction TCM Region Register accessible in the Secure and Non-secure worlds.
Instruction TCM is visible in the Non-secure world, and also in the Secure world if the NS
Attribute in the page table is 1.
Table 3-92 lists the effect on TCM operations for different combinations of operating world, and
NS bits.
NS
NS page
World
acces
table
s
Secure 0 1
1 0
0 0
1 1
Non-secure 1 X
0 X
Attempts to write to this register in Secure Privileged mode when CP15SDISABLE is HIGH
result in an Undefined exception, see TrustZone write access disable on page 2-9.
Copyright © 2004-2009 ARM Limited. All rights reserved.
Non-Confidential, Unrestricted Access
SBZ

Table 3-92 Effects of NS items for instruction TCM operation

Region
Control
visible
No -
No -
Yes Secure privileged only
Yes Secure and Non-secure privileged
Yes Secure and Non-secure privileged
No -
System Control Coprocessor
1 0
NS access
Data
-
-
Secure only
Non-secure only
Non-secure only
-
3-95