Primary Git Repository for the Zephyr Project. Zephyr is a new generation, scalable, optimized, secure RTOS for multiple hardware architectures.
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/**
* Copyright (c) 2025 STMicroelectronics
*
* SPDX-License-Identifier: Apache-2.0
*/
#ifndef ZEPHYR_INCLUDE_DRIVERS_TIMER_CORTEX_M_SYSTICK_H_
#define ZEPHYR_INCLUDE_DRIVERS_TIMER_CORTEX_M_SYSTICK_H_
#include <zephyr/types.h>
/**
* Hooks/callbacks definitions for interaction between the Cortex-M
* SysTick driver and a platform-specific low-power timer driver.
*
* These functions are invoked by the Cortex-M SysTick driver to
* configure a platform-specific timer that remains active when
* the system enters a low-power mode.
*
* In the rest of this file, the "platform-specific low-power mode timer"
* is named "LPTIM", and the platform-specific driver that configures the
* LPTIM (and implements these hooks/callbacks) is named "LPTIM driver".
*
* The following behavior is observed when this option is enabled:
*
* |------(1)---(2)--------------------(3)-------(4)--------------> Time
*
* (1) cmsd_hook_on_lpm_entry() is invoked
* (2) The system enters in low-power mode
* (3) The system exits low-power mode (due to timeout or HW event)
* (4) cmsd_hook_lpm_time_elapsed() is called
*
* The return value of cmsd_hook_lpm_time_elapsed() should be as close
* as possible to the real time interval between events (1) and (4).
*
* These hooks should be implemented by the application if and only if
* CONFIG_CORTEX_M_SYSTICK_LPM_TIMER_HOOKS is enabled.
*
* NOTE: the hooks are not invoked when the system enters in low-power
* mode for an indefinite amount of time (requires CONFIG_TICKLESS_KERNEL
* and no thread PENDING with timeout).
*/
/**
* @brief Hook invoked when the system is about to enter low-power mode
*
* @param max_lpm_time_us Maximal time allowed in low-power mode (µs)
*
* The LPTIM driver should configure the LPTIM to wake up the system
* after at most @a{max_lpm_time_us} elapses; depending on hardware
* capabilities, the LPTIM may have to be configured to wake up the
* system earlier than requested (but no later!).
*
* Note that this hook is not called if the system enters low-power
* mode for an indefinite amount of time (i.e., when no threads are
* runnable or waiting with timeout).
*/
void z_cms_lptim_hook_on_lpm_entry(uint64_t max_lpm_time_us);
/**
* @brief Callback invoked after system exits low-power mode
*
* This function should return the time elapsed, in microseconds,
* since entry in low-power mode occurred (i.e., since the call
* to @ref{cmsd_hook_on_lpm_entry}).
*/
uint64_t z_cms_lptim_hook_on_lpm_exit(void);
#endif /* ZEPHYR_INCLUDE_DRIVERS_TIMER_CORTEX_M_SYSTICK_H_ */