blob: 03673fe2d5616ab24dc5df87fa70d0c73e2b5e82 [file] [log] [blame]
/*
* Copyright (c) 2016 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <kernel.h>
#include <toolchain.h>
#include <linker/sections.h>
#include <drivers/timer/system_timer.h>
#include <wait_q.h>
#include <power/power.h>
#include <stdbool.h>
#include <logging/log.h>
#include <ksched.h>
LOG_MODULE_DECLARE(os, CONFIG_KERNEL_LOG_LEVEL);
#ifdef CONFIG_TICKLESS_IDLE_THRESH
#define IDLE_THRESH CONFIG_TICKLESS_IDLE_THRESH
#else
#define IDLE_THRESH 1
#endif
/* Fallback idle spin loop for SMP platforms without a working IPI */
#if (defined(CONFIG_SMP) && !defined(CONFIG_SCHED_IPI_SUPPORTED))
#define SMP_FALLBACK 1
#else
#define SMP_FALLBACK 0
#endif
#ifdef CONFIG_PM
/*
* Used to allow pm_system_suspend() implementation to control notification
* of the event that caused exit from kernel idling after pm operations.
*/
unsigned char pm_idle_exit_notify;
/* LCOV_EXCL_START
* These are almost certainly overidden and in any event do nothing
*/
void __attribute__((weak)) pm_system_resume(void)
{
}
void __attribute__((weak)) pm_system_resume_from_deep_sleep(void)
{
}
/* LCOV_EXCL_STOP */
#endif /* CONFIG_PM */
/**
*
* @brief Indicate that kernel is idling in tickless mode
*
* Sets the kernel data structure idle field to either a positive value or
* K_FOREVER.
*
* @param ticks the number of ticks to idle
*
* @return N/A
*/
#if !SMP_FALLBACK && CONFIG_PM
static enum pm_state pm_save_idle(int32_t ticks)
{
static enum pm_state idle_state = PM_STATE_ACTIVE;
pm_idle_exit_notify = 1U;
/*
* Call the suspend hook function of the soc interface to allow
* entry into a low power state. The function returns
* POWER_STATE_ACTIVE 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.
*/
idle_state = pm_system_suspend(ticks);
if (idle_state == PM_STATE_ACTIVE) {
pm_idle_exit_notify = 0U;
}
return idle_state;
}
#endif /* !SMP_FALLBACK */
void z_pm_save_idle_exit(int32_t ticks)
{
#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
* disabled by calling pm_idle_exit_notification_disable().
* Alternatively it can be simply ignored if not required.
*/
if (pm_idle_exit_notify) {
pm_system_resume();
}
#endif /* CONFIG_PM */
z_clock_idle_exit();
}
#if K_IDLE_PRIO < 0
#define IDLE_YIELD_IF_COOP() k_yield()
#else
#define IDLE_YIELD_IF_COOP() do { } while (false)
#endif
void idle(void *p1, void *unused2, void *unused3)
{
struct _cpu *cpu = p1;
ARG_UNUSED(unused2);
ARG_UNUSED(unused3);
#ifdef CONFIG_BOOT_TIME_MEASUREMENT
/* record timestamp when idling begins */
extern uint32_t z_timestamp_idle;
z_timestamp_idle = k_cycle_get_32();
#endif /* CONFIG_BOOT_TIME_MEASUREMENT */
while (true) {
/* Lock interrupts to atomically check if to_abort is non-NULL,
* and if so clear it
*/
int key = arch_irq_lock();
struct k_thread *to_abort = cpu->pending_abort;
if (to_abort) {
cpu->pending_abort = NULL;
arch_irq_unlock(key);
/* Safe to unlock interrupts here. We've atomically
* checked and stashed cpu->pending_abort into a stack
* variable. If we get preempted here and another
* thread aborts, cpu->pending abort will get set
* again and we'll handle it when the loop iteration
* is continued below.
*/
LOG_DBG("idle %p aborting thread %p",
_current, to_abort);
z_thread_single_abort(to_abort);
/* We have to invoke this scheduler now. If we got
* here, the idle thread preempted everything else
* in order to abort the thread, and we now need to
* figure out what to do next, it's not necessarily
* the case that there are no other runnable threads.
*/
z_reschedule_unlocked();
continue;
}
#if SMP_FALLBACK
arch_irq_unlock(key);
k_busy_wait(100);
k_yield();
#else
#ifdef CONFIG_SYS_CLOCK_EXISTS
int32_t ticks = z_get_next_timeout_expiry();
/* The documented behavior of CONFIG_TICKLESS_IDLE_THRESH is
* that the system should not enter a tickless idle for
* periods less than that. This seems... silly, given that it
* saves no power and does not improve latency. But it's an
* API we need to honor...
*/
z_set_timeout_expiry((ticks < IDLE_THRESH) ? 1 : ticks, true);
#ifdef CONFIG_PM
_kernel.idle = ticks;
/* Check power policy and decide if we are going to sleep or
* just idle.
*/
if (pm_save_idle(ticks) == PM_STATE_ACTIVE) {
k_cpu_idle();
}
#else /* CONFIG_PM */
k_cpu_idle();
#endif /* CONFIG_PM */
#else /* CONFIG_SYS_CLOCK_EXISTS */
k_cpu_idle();
#endif /* CONFIG_SYS_CLOCK_EXISTS */
IDLE_YIELD_IF_COOP();
#endif /* SMP_FALLBACK */
}
}