9.2 Generic Timer functional description
The Cortex-A72 processor provides a set of timers for each core in the processor.
The timers are:
- A Non-secure EL1 physical timer.
- A Secure EL1 physical timer.
- A Non-secure EL2 physical timer.
- A virtual timer.
The processor does not include the system counter that resides in the SoC.
The system counter value is distributed to the Cortex-A72 processor with a synchronous
binary encoded 64-bit bus, CNTVALUEB[63:0].
Because CNTVALUEB is generated from a system
counter that typically operates at a slower frequency than the main processor CLK, the CNTCLKEN input is provided as a clock enable for the CNTVALUEB
Each timer provides an active-LOW interrupt output that is an external pin to the SoC.
The following table shows the signals that are the external interrupt output pins.
Table 9-1 Generic Timer signals
||Non-secure EL1 physical timer interrupt
||Secure EL1 physical timer interrupt
||Non-secure EL2 physical timer interrupt
||Virtual timer interrupt