drivers/timer/Kconfig.system_timer_lpm

# Copyright (c) 2026 NXP
# SPDX-License-Identifier: Apache-2.0

DT_CHOSEN_SYSTEM_TIMER_COMPANION := zephyr,system-timer-companion
DT_CHOSEN_SYSTEM_TIMER_COMPANION_LEGACY := zephyr,cortex-m-idle-timer

config SYSTEM_TIMER_HAS_LPM_COMPANION_SUPPORT
	bool
	help
	  This option should be selected by system timer drivers that support
	  delegating low-power timekeeping to a companion timer.

# If all dependencies are enabled, and either the preferred
# /chosen/zephyr,system-timer-companion property or the deprecated
# /chosen/zephyr,cortex-m-idle-timer property is enabled, default
# to using the Counter API-based LPM timer. Otherwise, the first
# choice (SYSTEM_TIMER_LPM_COMPANION_NONE) will be selected automatically,
# and no LPM companion timer will be enabled.
choice SYSTEM_TIMER_LPM_COMPANION
	prompt "System timer low-power companion"
	depends on SYSTEM_TIMER_HAS_LPM_COMPANION_SUPPORT
	# Preserve legacy SysTick Kconfig selections during the deprecation period.
	# These defaults are scheduled to be removed in Zephyr 4.6.0.
	default SYSTEM_TIMER_LPM_COMPANION_COUNTER if CORTEX_M_SYSTICK_LPM_TIMER_COUNTER
	default SYSTEM_TIMER_LPM_COMPANION_HOOKS if CORTEX_M_SYSTICK_LPM_TIMER_HOOKS
	default SYSTEM_TIMER_LPM_COMPANION_NONE if CORTEX_M_SYSTICK_LPM_TIMER_NONE
	default SYSTEM_TIMER_LPM_COMPANION_COUNTER
	help
	  On some platforms, the timer that is best suited for use as the active
	  system timer cannot keep time while the system is in a low-power state.
	  A separate timer may remain active in those states but still be a poor
	  fit as the primary system timer, for example due to lower resolution.

	  With this option, the primary system timer can hand over timekeeping to
	  a low-power companion across low-power transitions and recover the
	  elapsed time on wakeup.

	  NOTE: since Power Management has to be enabled if the SoC may enter in
	  low-power mode, no LPM companion can be selected if PM is not enabled.
	  Tickless kernel must also be enabled, since periodic interrupts would
	  prevent the system from entering in low-power modes.

config SYSTEM_TIMER_LPM_COMPANION_NONE
	bool "None"
	help
	  Use no additional device as the system timer low-power companion.

	  The platform must never enter a low-power mode where the active system
	  timer cannot keep time when this option is selected; otherwise, system
	  behavior becomes unpredictable.

if TICKLESS_KERNEL && PM

config SYSTEM_TIMER_LPM_COMPANION_COUNTER
	bool "Counter API timer"
	depends on $(dt_chosen_enabled,$(DT_CHOSEN_SYSTEM_TIMER_COMPANION)) || \
		   $(dt_chosen_enabled,$(DT_CHOSEN_SYSTEM_TIMER_COMPANION_LEGACY))
	depends on COUNTER
	help
	  Use a device that implements the Counter API as the system timer
	  low-power companion.

	  The device is selected by the chosen property
	  "/chosen/zephyr,system-timer-companion".

	  The legacy compatibility property
	  "/chosen/zephyr,cortex-m-idle-timer" is deprecated but still accepted.

config SYSTEM_TIMER_LPM_COMPANION_HOOKS
	bool "Hook-based timer"
	help
	  Use platform hooks to configure the system timer low-power companion.
	  Refer to `include/zephyr/drivers/timer/system_timer_lpm.h` for more
	  details.

endif # TICKLESS_KERNEL && PM
endchoice # SYSTEM_TIMER_LPM_COMPANION

config SYSTEM_TIMER_RESET_BY_LPM
	bool "System timer reset by low-power mode"
	depends on !SYSTEM_TIMER_LPM_COMPANION_NONE
	help
	  Some platforms provide one or more low-power modes which, as part
	  of their operation, place the active system timer under reset. This
	  requires special care from the driver, notably restarting the timer
	  and reconstructing elapsed time after wakeup.

	  Select this option if your platform may enter such a low-power mode and
	  a system timer low-power companion is required for reliable timekeeping.

	  Refer to CONFIG_SYSTEM_TIMER_LPM_COMPANION for more details.