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CNTTIDR, Counter-timer Timer ID Register

The CNTTIDR characteristics are:

Purpose

Indicates the implemented timers in the memory map, and their features. For each value of N from 0 to 7 it indicates whether:

  • Frame CNTBaseN is a view of an implemented timer.
  • Frame CNTBaseN has a second view, CNTEL0BaseN.
  • Frame CNTBaseN has a virtual timer capability.

Configuration

The power domain of CNTTIDR is IMPLEMENTATION DEFINED.

For more information see 'Power and reset domains for the system level implementation of the Generic Timer' in Chapter I1 of the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

Attributes

CNTTIDR is a 32-bit register.

Field descriptions

The CNTTIDR bit assignments are:

313029282726252423222120191817161514131211109876543210
Frame7Frame6Frame5Frame4Frame3Frame2Frame1Frame0

Frame<n>, bits [4n+3:4n], for n = 0 to 7

A 4-bit field indicating the features of frame CNTBase<n>.

Bit[3] of the field is RES0.

Bit[2], the FEL0 subfield, indicates whether frame CNTBase<n> has a second view, CNTEL0Base<n>. The possible values of this bit are:

Bit[2]Meaning
0b0Frame<n> does not have a second view. The CNTEL0ACR register in the first view of the frame is RES0
0b1Frame<n> has a second view, CNTEL0Base<n>.

If bit[0] is 0, bit[2] is RES0.

Bit[1], the FVI subfield, indicates whether both:

The possible values of bit[1] are:

Bit[1]Meaning
0b0Frame<n> does not have virtual capability. The virtual time and offset registers are RES0.
0b1Frame<n> has virtual capability. The virtual time and offset registers are implemented

If bit[0] is 0, bit[1] is RES0.

Bit[0], the FI subfield, indicates whether frame CNTBase<n> is implemented. The possible values of this bit are:

Bit[0]Meaning
0b0Frame<n> is not implemented. All registers associated with the frame are RES0.
0b1Frame<n> is implemented

Accessing the CNTTIDR

In a system that recognizes two Security states this register is accessible by both Secure and Non-secure accesses.

CNTTIDR can be accessed through the memory-mapped interfaces:

ComponentFrameOffsetInstance
TimerCNTCTLBase0x008CNTTIDR

Accesses on this interface are RO.



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