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

DT_CHOSEN_IDLE_TIMER := zephyr,cortex-m-idle-timer

config CORTEX_M_SYSTICK
	bool "Cortex-M SYSTICK timer"
	depends on CPU_CORTEX_M_HAS_SYSTICK
	default y
	depends on DT_HAS_ARM_ARMV6M_SYSTICK_ENABLED || \
		   DT_HAS_ARM_ARMV7M_SYSTICK_ENABLED || \
		   DT_HAS_ARM_ARMV8M_SYSTICK_ENABLED || \
		   DT_HAS_ARM_ARMV8_1M_SYSTICK_ENABLED
	select TICKLESS_CAPABLE
	select SYSTEM_TIMER_HAS_DISABLE_SUPPORT
	select CORTEX_M_SYSTICK_INSTALL_ISR
	help
	  This module implements a kernel device driver for the Cortex-M processor
	  SYSTICK timer and provides the standard "system clock driver" interfaces.

config CORTEX_M_SYSTICK_INSTALL_ISR
	bool
	depends on CPU_CORTEX_M_HAS_SYSTICK
	help
	  This option should be selected by SysTick-based drivers so that the
	  sys_clock_isr() function is installed.

config CORTEX_M_SYSTICK_64BIT_CYCLE_COUNTER
	bool "Cortex-M SYSTICK timer with sys_clock_cycle_get_64() support"
	depends on CORTEX_M_SYSTICK
	default y if (SYS_CLOCK_HW_CYCLES_PER_SEC > 60000000)
	select TIMER_HAS_64BIT_CYCLE_COUNTER
	help
	  This driver, due to its limited 24-bits hardware counter, is already
	  tracking a separate cycle count in software. This option make that
	  count a 64-bits value to support sys_clock_cycle_get_64().
	  This is cheap to do as expensive math operations (i.e. divisions)
	  are performed only on counter interval values that always fit in
	  32 bits.

	  This is set to y by default when the hardware clock is fast enough
	  to wrap sys_clock_cycle_get_32() in about a minute or less.

choice CORTEX_M_SYSTICK_LPM_TIMER
	prompt "SysTick companion low-power mode timer"
	# If all dependencies are enabled, and /chosen/cortex-m-idle-timer
	# is enabled, default to using the Counter API-based LPM timer.
	# Otherwise, the first choice (LPM_TIMER_NONE) will be selected
	# automatically, and no LPM timer will be enabled.
	default CORTEX_M_SYSTICK_LPM_TIMER_COUNTER
	help
	  It is common for SoCs equipped with SysTick to use it as system timer.
	  However, depending on the SoC implementation, entering low-power mode
	  may turn off the SysTick clock or place SysTick under reset.

	  On such SoCs, a vendor-specific timer that remains active in low-power
	  mode will usually be provided - however, it may be unfit for usage as
	  system timer, for example because its frequency is too low.

	  With this option, such vendor-specific timer can be selected and used by
	  the SysTick driver to ensure proper system operation in low-power mode.

	  NOTE: since Power Management has to be enabled if the SoC may enter in
	  low-power mode, no LPM timer 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 CORTEX_M_SYSTICK_LPM_TIMER_NONE
	bool "None"
	help
	  Use no additional device as low-power mode timer.

	  The SoC must never enter a low-power mode where SysTick is disabled when
	  this option is selected; otherwise, system behavior becomes unpredictable.

if TICKLESS_KERNEL && PM

config CORTEX_M_SYSTICK_LPM_TIMER_COUNTER
	bool "Counter API timer"
	depends on $(dt_chosen_enabled,$(DT_CHOSEN_IDLE_TIMER))
	depends on COUNTER
	help
	  Use a device that implements the counter API as low-power mode timer.

	  The device is selected by property "/chosen/cortex-m-idle-timer".

config CORTEX_M_SYSTICK_LPM_TIMER_HOOKS
	bool "Hook-based timer"
	help
	  Use hooks in the SysTick driver to configure the low-power mode timer.
	  Refer to `include/drivers/timer/cortex_m_systick.h` for more details.

endif # PM
endchoice # CORTEX_M_SYSTICK_LPM_TIMER

config CORTEX_M_SYSTICK_RESET_BY_LPM
	bool
	depends on !CORTEX_M_SYSTICK_LPM_TIMER_NONE
	help
	  Some SoCs provide one or more low-power mode which, as part of their
	  operation, place SysTick or the entire CPU under reset. This requires
	  special care from the driver - notably, SysTick needs to be restarted
	  after waking up from such a low-power mode.

	  Select this symbol if your SoC has a low-power mode that places SysTick
	  under reset. Note that this requires that the platform provides a timer
	  active in low-power mode, since SysTick cannot be used for timekeeping.

	  Refer to CONFIG_CORTEX_M_SYSTICK_LPM_TIMER for more details.