drivers/timer/Kconfig.x86

# Copyright (c) 2014-2015 Wind River Systems, Inc.
# Copyright (c) 2016 Cadence Design Systems, Inc.
# Copyright (c) 2019-2023 Intel Corp.
# SPDX-License-Identifier: Apache-2.0

choice
	prompt "Default System Timer"
	default HPET_TIMER if SOC_FAMILY_INTEL_ISH || SOC_ATOM || SOC_LAKEMONT
	default APIC_TSC_DEADLINE_TIMER
	depends on X86
	help
	  Select Default System Timer.

config HPET_TIMER
	bool "HPET timer"
	depends on DT_HAS_INTEL_HPET_ENABLED
	select IOAPIC
	select LOAPIC
	imply TIMER_READS_ITS_FREQUENCY_AT_RUNTIME
	select TICKLESS_CAPABLE
	select TIMER_HAS_64BIT_CYCLE_COUNTER
	help
	  This option selects High Precision Event Timer (HPET) as a
	  system timer.

config APIC_TIMER
	bool "Local APIC timer"
	select LOAPIC
	select TICKLESS_CAPABLE
	select SYSTEM_CLOCK_LOCK_FREE_COUNT
	help
	  Use the x86 local APIC in one-shot mode as the system time
	  source.  NOTE: this probably isn't what you want except on
	  older or idiosyncratic hardware (or environments like qemu
	  without complete APIC emulation).  Modern hardware will work
	  better with CONFIG_APIC_TSC_DEADLINE_TIMER.

config APIC_TSC_DEADLINE_TIMER
	bool "Local APIC timer using TSC deadline mode"
	select LOAPIC
	select TICKLESS_CAPABLE
	select TIMER_HAS_64BIT_CYCLE_COUNTER
	help
	  Extremely simple timer driver based the local APIC TSC
	  deadline capability.  The use of a free-running 64 bit
	  counter with comparator eliminates almost all edge cases
	  from the handling, and the near-instruction-cycle resolution
	  permits effectively unlimited precision where needed (the
	  limit becomes the CPU time taken to execute the timing
	  logic). SMP-safe and very fast, this should be the obvious
	  choice for any x86 device with invariant TSC and TSC
	  deadline capability.

endchoice

if APIC_TIMER

config APIC_TIMER_IRQ
	int "Local APIC timer IRQ"
	default 24
	help
	  This option specifies the IRQ used by the local APIC timer.
	  Note: this MUST be set to the index immediately after the
	  last IO-APIC IRQ (the timer is the first entry in the APIC
	  local vector table).  This footgun is not intended to be
	  user-configurable and almost certainly should be managed via
	  a different mechanism.

config APIC_TIMER_TSC
	bool "Use invariant TSC for sys_clock_cycle_get_32()"
	select TIMER_HAS_64BIT_CYCLE_COUNTER
	help
	  If your CPU supports invariant TSC, and you know the ratio of the
	  TSC frequency to CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC (the local APIC
	  timer frequency), then enable this for a much faster and more
	  accurate sys_clock_cycle_get_32().

if APIC_TIMER_TSC

config APIC_TIMER_TSC_N
	int "TSC to local APIC timer frequency multiplier (N)"
	default 1

config APIC_TIMER_TSC_M
	int "TSC to local APIC timer frequency divisor (M)"
	default 1

endif # APIC_TIMER_TSC

endif # APIC_TIMER

config APIC_TIMER_IRQ_PRIORITY
	int "Local APIC timer interrupt priority"
	depends on APIC_TIMER || APIC_TSC_DEADLINE_TIMER
	default 4
	help
	  This option specifies the interrupt priority used by the
	  local APIC timer.