The GPTIMER is part of the GRLIB device library from Gaisler. The timer runs using synchronised events in order to ensure that would a timer tick be broadcasted by the interrupt controller, then the IRQ should be taken at roughly the same time.
Set the "config.separateInterrupts" property to non-zero.
The interrupt number can be set by configuring the "pnp.config" property. The lower 5 bits of the property is used for this.
Number of Timers
Set the "config.numTimers" property. By default this value is 4 to be compatible with the UT699.
Clear IRQ on Set
Set the "config.clearIrqOnSet" property changes the behaviour of bit 4 in the timer control registers. ClearOnSet can be non-zero (the default), in that case writing a 1 to the bit will clear bit 4 (i.e. it will read out as 0), if clearOnSet is zero, the bit is cleared if bit 4 is 0 in the written word.
The reason for this are ambiguities in the LEON3 and UT699 manuals.
The following deviations from real hardware are known to exist with this model:
The Disable Timer Freeze bit is always 1 and cannot be configured.
The Debug Halt bit for each timer is always 0 and cannot be altered.
Chained timers are not supported at the moment.
The last timer does not work as a watchdog.
As the timer utilise synchronised events, the minimum time for a timer expiration on a multi-core CPU would be equal to the time-quanta that the machine has been configured with.