CNTNSAR, Counter-timer Non-secure Access Register
The CNTNSAR characteristics are:
Purpose
Provides the highest-level control of whether frames CNTBaseN and CNTEL0BaseN are accessible by Non-secure accesses.
Configuration
The power domain of CNTNSAR is IMPLEMENTATION DEFINED.
For more information, see 'Power and reset domains for the system level implementation of the Generic Timer'.
Attributes
CNTNSAR is a 32-bit register.
Field descriptions
The CNTNSAR bit assignments are:
Bits [31:8]
Reserved, RES0.
NS<n>, bit [n], for n = 0 to 7
Non-secure access to frame n. The possible values of this bit are:
NS<n> | Meaning |
---|---|
0b0 |
Secure access only. Behaves as RES0 to Non-secure accesses. |
0b1 |
Secure and Non-secure accesses permitted. |
This bit also determines whether, in the CNTCTLBase frame, CNTACR<n> and CNTVOFF<n> are accessible to Non-secure accesses.
If frame CNTBase<n>:
- Is not implemented, then NS<n> is RES0.
- Is not Configurable access, and is accessible only by Secure accesses, then NS<n> is RES0.
- Is not Configurable access, and is accessible by both Secure and Non-secure accesses, then NS<n> is RES1.
This field resets to an architecturally UNKNOWN value.
Accessing the CNTNSAR
In a system that recognizes two Security states, this register is only accessible by Secure accesses.
CNTNSAR can be accessed through the memory-mapped interfaces:
Component | Frame | Offset | Instance |
---|---|---|---|
Timer | CNTCTLBase | 0x004 | CNTNSAR |
Accesses on this interface are RW.