103 lines
3.1 KiB
Plaintext
103 lines
3.1 KiB
Plaintext
# Copyright (c) 2014-2015 Wind River Systems, Inc.
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# Copyright (c) 2016 Cadence Design Systems, Inc.
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# Copyright (c) 2019-2023 Intel Corp.
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# SPDX-License-Identifier: Apache-2.0
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choice
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prompt "Default System Timer"
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default HPET_TIMER if SOC_FAMILY_INTEL_ISH || SOC_ATOM || SOC_LAKEMONT
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default APIC_TSC_DEADLINE_TIMER
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depends on X86
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help
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Select Default System Timer.
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config HPET_TIMER
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bool "HPET timer"
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depends on DT_HAS_INTEL_HPET_ENABLED
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select IOAPIC
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select LOAPIC
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imply TIMER_READS_ITS_FREQUENCY_AT_RUNTIME
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select TICKLESS_CAPABLE
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select TIMER_HAS_64BIT_CYCLE_COUNTER
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help
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This option selects High Precision Event Timer (HPET) as a
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system timer.
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config APIC_TIMER
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bool "Local APIC timer"
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select LOAPIC
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select TIMER_HAS_64BIT_CYCLE_COUNTER
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select SYSTEM_CLOCK_LOCK_FREE_COUNT
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help
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Use the x86 local APIC in periodic mode as the system time
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source. NOTE: this probably isn't what you want except on
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older or idiosyncratic hardware (or environments like qemu
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without complete APIC emulation). Modern hardware will work
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better with CONFIG_APIC_TSC_DEADLINE_TIMER.
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config APIC_TSC_DEADLINE_TIMER
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bool "Local APIC timer using TSC deadline mode"
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select LOAPIC
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select TICKLESS_CAPABLE
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select TIMER_HAS_64BIT_CYCLE_COUNTER
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help
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Extremely simple timer driver based the local APIC TSC
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deadline capability. The use of a free-running 64 bit
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counter with comparator eliminates almost all edge cases
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from the handling, and the near-instruction-cycle resolution
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permits effectively unlimited precision where needed (the
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limit becomes the CPU time taken to execute the timing
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logic). SMP-safe and very fast, this should be the obvious
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choice for any x86 device with invariant TSC and TSC
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deadline capability.
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config APIC_TIMER_TSC
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bool "Local APIC timer using TSC time source"
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depends on !SMP
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select LOAPIC
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select TICKLESS_CAPABLE
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select TIMER_HAS_64BIT_CYCLE_COUNTER
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help
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If your CPU supports invariant TSC but no TSC deadline capability
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then this choice will rely on the TSC as time source and the
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local APIC in one-shot mode as the timeout event source.
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You must know the ratio of the TSC frequency to the local APIC
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timer frequency.
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endchoice
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if APIC_TIMER
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config APIC_TIMER_IRQ
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int "Local APIC timer IRQ"
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default 24
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help
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This option specifies the IRQ used by the local APIC timer.
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Note: this MUST be set to the index immediately after the
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last IO-APIC IRQ (the timer is the first entry in the APIC
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local vector table). This footgun is not intended to be
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user-configurable and almost certainly should be managed via
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a different mechanism.
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endif # APIC_TIMER
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if APIC_TIMER_TSC
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config APIC_TIMER_TSC_N
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int "TSC to local APIC timer frequency multiplier (N)"
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default 1
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config APIC_TIMER_TSC_M
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int "TSC to local APIC timer frequency divisor (M)"
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default 1
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endif # APIC_TIMER_TSC
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config APIC_TIMER_IRQ_PRIORITY
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int "Local APIC timer interrupt priority"
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depends on APIC_TIMER || APIC_TSC_DEADLINE_TIMER || APIC_TIMER_TSC
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default 4
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help
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This option specifies the interrupt priority used by the
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local APIC timer.
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