Table 3-89 Data Tcm Non-Secure Control Access Register Bit Functions; Table 3-90 Effects Of Ns Items For Data Tcm Operation - ARM ARM1176JZF-S Technical Reference Manual

Bits Field name
[31:1] -
[0] NS access
3.2.28 c9, Instruction TCM Non-secure Control Access Register
ARM DDI 0301H
ID012310
Table 3-89 lists how the bit values correspond with the register functions.

Table 3-89 Data TCM Non-secure Control Access Register bit functions

Function
UNP/SBZ.
Makes Data TCM invisible to the Non-secure world and makes TCM data Secure.
0 = Data TCM Region Register only accessible in the Secure world. Data 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 = Data TCM Region Register accessible in the Secure and Non-secure worlds. Data 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 3-90 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.
Attempts to access the Data TCM Non-secure Control Access Register in modes other than
Secure privileged result in an Undefined exception.
To use the Data TCM Non-secure Control Access Register read or write CP15 with:
• Opcode_1 set to 0
• CRn set to c9
• CRm set to c1
• Opcode_2 set to 2.
For example:
MRC p15,0,<Rd>,c9,c1,2
MCR p15,0,<Rd>,c9,c1,2
The purpose of the Instruction TCM Non-secure Control Access Register is to:
• set access permission to the Instruction TCM Region Register
• define instructions in the Instruction TCM as Secure or Non-secure.
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Table 3-90 Effects of NS items for data TCM operation

Region
Control
visible
No -
No -
Yes Secure privileged only
Yes Secure and Non-secure privileged
Yes Secure and Non-secure privileged
No -
; Read Data TCM Non-secure Control Access Register
; Write Data TCM Non-secure Control Access Register
System Control Coprocessor
Data
-
-
Secure only
Non-secure only
Non-secure only
-
3-94