blob: ae6fffd83f01e8f9d0b54272ee672fd58f0271e8 [file] [log] [blame]
* Copyright (c) 2016 Wind River Systems, Inc.
* SPDX-License-Identifier: Apache-2.0
#include <zephyr/kernel.h>
#include <zephyr/toolchain.h>
#include <zephyr/linker/sections.h>
#include <zephyr/drivers/timer/system_timer.h>
#include <zephyr/wait_q.h>
#include <zephyr/pm/pm.h>
#include <stdbool.h>
#include <zephyr/logging/log.h>
#include <ksched.h>
#include <kswap.h>
void z_pm_save_idle_exit(void)
#ifdef CONFIG_PM
/* Some CPU low power states require notification at the ISR
* to allow any operations that needs to be done before kernel
* switches task or processes nested interrupts.
* This can be simply ignored if not required.
#endif /* CONFIG_PM */
void idle(void *unused1, void *unused2, void *unused3)
__ASSERT_NO_MSG(_current->base.prio >= 0);
while (true) {
/* SMP systems without a working IPI can't
* actual enter an idle state, because they
* can't be notified of scheduler changes
* (i.e. threads they should run). They just
* spin in a yield loop. This is intended as
* a fallback configuration for new platform
* bringup.
/* Note weird API: k_cpu_idle() is called with local
* CPU interrupts masked, and returns with them
* unmasked. It does not take a spinlock or other
* higher level construct.
(void) arch_irq_lock();
#ifdef CONFIG_PM
_kernel.idle = z_get_next_timeout_expiry();
* Call the suspend hook function of the soc interface
* to allow entry into a low power state. The function
* returns false if low power state was not entered, in
* which case, kernel does normal idle processing.
* This function is entered with interrupts disabled.
* If a low power state was entered, then the hook
* function should enable inerrupts before exiting.
* This is because the kernel does not do its own idle
* processing in those cases i.e. skips k_cpu_idle().
* The kernel's idle processing re-enables interrupts
* which is essential for the kernel's scheduling
* logic.
if (k_is_pre_kernel() || !pm_system_suspend(_kernel.idle)) {
# if !defined(CONFIG_USE_SWITCH) || defined(CONFIG_SPARC)
/* A legacy mess: the idle thread is by definition
* preemptible as far as the modern scheduler is
* concerned, but older platforms use
* CONFIG_PREEMPT_ENABLED=n as an optimization hint
* that interrupt exit always returns to the
* interrupted context. So in that setup we need to
* explicitly yield in the idle thread otherwise
* nothing else will run once it starts.
if (_kernel.ready_q.cache != _current) {
# endif