NAME
hpet —
High Precision Event Timer
SYNOPSIS
hpet* at acpihpetbus?
hpet* at acpinodebus?
hpet* at amdpcib?
hpet* at ichlpcib?
DESCRIPTION
Thehpet driver supports High Precision Event Timers
(HPETs). The HPET architecture defines one main 64-bit counter and several
additional timers with variable width. The minimum clock frequency of the main
timecounter is 10 MHz, but much higher rates are common. The additional 32 or
64 -bit parts are typically accessible via MMIO that is set by the system BIOS
through ACPI.
As a HPET can provide higher interrupt rates than a RTC or attimer(4), multimedia is one typical application context. The interrupt logic is configurable through I/O APIC, but a legacy mode is provided for older systems.
SEE ALSO
acpi(4), attimer(4), timecounter(9), tsc(9)
Intel Corporation, IA-PC HPET (High Precision Event Timers) Specification, Revision 1.0a, http://www.intel.com/hardwaredesign/hpetspec_1.pdf, October, 2004.