blob: 1ed393a3e942e880d979e998b1c1fffb743a2f9b [file] [log] [blame]
/*
* Copyright (c) 2016 Wind River Systems, Inc.
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <kernel.h>
#include <kernel_structs.h>
#include <toolchain.h>
#include <linker/sections.h>
#include <drivers/system_timer.h>
#include <wait_q.h>
#include <power.h>
#if defined(CONFIG_TICKLESS_IDLE)
/*
* Idle time must be this value or higher for timer to go into tickless idle
* state.
*/
s32_t _sys_idle_threshold_ticks = CONFIG_TICKLESS_IDLE_THRESH;
#if defined(CONFIG_TICKLESS_KERNEL)
#define _must_enter_tickless_idle(ticks) (1)
#else
#define _must_enter_tickless_idle(ticks) \
((ticks == K_FOREVER) || (ticks >= _sys_idle_threshold_ticks))
#endif
#else
#define _must_enter_tickless_idle(ticks) ((void)ticks, (0))
#endif /* CONFIG_TICKLESS_IDLE */
#ifdef CONFIG_SYS_POWER_MANAGEMENT
/*
* Used to allow _sys_soc_suspend() implementation to control notification
* of the event that caused exit from kernel idling after pm operations.
*/
unsigned char _sys_pm_idle_exit_notify;
void __attribute__((weak)) _sys_soc_resume(void)
{
}
void __attribute__((weak)) _sys_soc_resume_from_deep_sleep(void)
{
}
/**
*
* @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
*/
static void set_kernel_idle_time_in_ticks(s32_t ticks)
{
_kernel.idle = ticks;
}
#else
#define set_kernel_idle_time_in_ticks(x) do { } while (0)
#endif
#ifndef CONFIG_SMP
static void sys_power_save_idle(s32_t ticks)
{
#ifdef CONFIG_TICKLESS_KERNEL
if (ticks != K_FOREVER) {
ticks -= _get_elapsed_program_time();
if (!ticks) {
/*
* Timer has expired or about to expire
* No time for power saving operations
*
* Note that it will never be zero unless some time
* had elapsed since timer was last programmed.
*/
k_cpu_idle();
return;
}
}
#endif
if (_must_enter_tickless_idle(ticks)) {
/*
* Stop generating system timer interrupts until it's time for
* the next scheduled kernel timer to expire.
*/
/*
* In the case of tickless kernel, timer driver should
* reprogram timer only if the currently programmed time
* duration is smaller than the idle time.
*/
_timer_idle_enter(ticks);
}
set_kernel_idle_time_in_ticks(ticks);
#if (defined(CONFIG_SYS_POWER_LOW_POWER_STATE) || \
defined(CONFIG_SYS_POWER_DEEP_SLEEP))
_sys_pm_idle_exit_notify = 1;
/*
* Call the suspend hook function of the soc interface to allow
* entry into a low power state. The function returns
* SYS_PM_NOT_HANDLED 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 (_sys_soc_suspend(ticks) == SYS_PM_NOT_HANDLED) {
_sys_pm_idle_exit_notify = 0;
k_cpu_idle();
}
#else
k_cpu_idle();
#endif
}
#endif
void _sys_power_save_idle_exit(s32_t ticks)
{
#if defined(CONFIG_SYS_POWER_LOW_POWER_STATE)
/* 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 _sys_soc_pm_idle_exit_notification_disable().
* Alternatively it can be simply ignored if not required.
*/
if (_sys_pm_idle_exit_notify) {
_sys_soc_resume();
}
#endif
if (_must_enter_tickless_idle(ticks)) {
/* Resume normal periodic system timer interrupts */
_timer_idle_exit();
}
}
#if K_IDLE_PRIO < 0
#define IDLE_YIELD_IF_COOP() k_yield()
#else
#define IDLE_YIELD_IF_COOP() do { } while ((0))
#endif
void idle(void *unused1, void *unused2, void *unused3)
{
ARG_UNUSED(unused1);
ARG_UNUSED(unused2);
ARG_UNUSED(unused3);
#ifdef CONFIG_BOOT_TIME_MEASUREMENT
/* record timestamp when idling begins */
extern u64_t __idle_time_stamp;
__idle_time_stamp = (u64_t)k_cycle_get_32();
#endif
#ifdef CONFIG_SMP
/* Simplified idle for SMP CPUs pending driver support. The
* busy waiting is needed to prevent lock contention. Long
* term we need to wake up idle CPUs with an IPI.
*/
while (1) {
k_busy_wait(100);
k_yield();
}
#else
for (;;) {
(void)irq_lock();
sys_power_save_idle(_get_next_timeout_expiry());
IDLE_YIELD_IF_COOP();
}
#endif
}