ardupilot/libraries/AP_HAL_SMACCM/Scheduler.cpp

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/* -*- Mode: C++; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
* Scheduler.cpp --- AP_HAL_SMACCM scheduler.
*
* Copyright (C) 2012, Galois, Inc.
* All Rights Reserved.
*
* This software is released under the "BSD3" license. Read the file
* "LICENSE" for more information.
*
* Written by James Bielman <jamesjb@galois.com>, 20 December 2012
*/
#include <AP_HAL_Boards.h>
#if CONFIG_HAL_BOARD == HAL_BOARD_SMACCM
#include <hwf4/gpio.h>
#include <hwf4/timer.h>
#include <FreeRTOS.h>
#include <task.h>
#include <semphr.h>
#include "Scheduler.h"
using namespace SMACCM;
extern const AP_HAL::HAL& hal;
/** Rate in milliseconds of timed process execution. (1kHz) */
#define SCHEDULER_TICKS (1 / (portTICK_RATE_MS))
/** Stack size of the scheduler thread. */
#define SCHEDULER_STACK_SIZE 1536
/** Priority of the scheduler timer process task. */
#define SCHEDULER_PRIORITY (configMAX_PRIORITIES - 1)
/** Rate in milliseconds of the delay callback task. */
#define DELAY_CB_TICKS (1 / (portTICK_RATE_MS))
/** Stack size of the delay callback task. */
#define DELAY_CB_STACK_SIZE 512
/** Priority of the delay callback task. */
#define DELAY_CB_PRIORITY 0
/**
* Recursive mutex used to block "scheduler_task" during atomic
* sections.
*/
static xSemaphoreHandle g_atomic;
/** High-priority thread managing timer procedures. */
static void scheduler_task(void *arg)
{
SMACCMScheduler *sched = (SMACCMScheduler *)arg;
portTickType last_wake_time;
portTickType now;
vTaskSetApplicationTaskTag(NULL, (pdTASK_HOOK_CODE)3);
last_wake_time = xTaskGetTickCount();
for (;;) {
/* If "vTaskDelayUntil" would return immediately without blocking,
* call the failsafe callback to notify the client that we've
* missed our deadline, and reset the wakeup time to the current
* time. */
now = xTaskGetTickCount();
if (last_wake_time + SCHEDULER_TICKS <= now) {
sched->run_failsafe_cb();
last_wake_time = now;
} else {
vTaskDelayUntil(&last_wake_time, SCHEDULER_TICKS);
xSemaphoreTakeRecursive(g_atomic, portMAX_DELAY);
sched->run_callbacks();
xSemaphoreGiveRecursive(g_atomic);
}
}
}
/** Count of the number of threads in "delay". */
static uint32_t g_delay_count;
/** Binary semaphore given when a thread enters "delay". */
static xSemaphoreHandle g_delay_event;
/**
* Low-priority thread that calls the delay callback every 1ms.
*
* Whenever any thread enters a call to "delay", it unblocks this
* task.
*
* We use a count of the number of threads currently in "delay"
* because there could be more than one.
*/
static void delay_cb_task(void *arg)
{
SMACCMScheduler *sched = (SMACCMScheduler *)arg;
portTickType last_wake_time;
portTickType now;
vTaskSetApplicationTaskTag(NULL, (pdTASK_HOOK_CODE)4);
last_wake_time = xTaskGetTickCount();
for (;;) {
portENTER_CRITICAL();
uint32_t delay_count = g_delay_count;
portEXIT_CRITICAL();
if (delay_count > 0) {
/* If some thread is in "delay", call the delay callback. */
sched->run_delay_cb();
/* If "vTaskDelayUntil" would return immediately without
* blocking, that means we've missed our deadline. However,
* this thread is best-effort, so we'll just readjust our
* schedule accordingly and run 1ms from now.
*
* Without this, the thread runs many times to "catch up" if
* something takes too long in a higher priority thread. */
now = xTaskGetTickCount();
if (last_wake_time + DELAY_CB_TICKS <= now) {
last_wake_time = now;
} else {
vTaskDelayUntil(&last_wake_time, DELAY_CB_TICKS);
}
} else {
/* Wait for a thread to enter a delay. */
xSemaphoreTake(g_delay_event, portMAX_DELAY);
last_wake_time = xTaskGetTickCount();
}
}
}
SMACCMScheduler::SMACCMScheduler()
: m_delay_cb(NULL), m_task(NULL), m_delay_cb_task(NULL),
m_failsafe_cb(NULL), m_num_procs(0), m_initializing(true)
{
}
void SMACCMScheduler::init(void *arg)
{
timer_init();
g_atomic = xSemaphoreCreateRecursiveMutex();
vSemaphoreCreateBinary(g_delay_event);
xSemaphoreTake(g_delay_event, portMAX_DELAY);
xTaskCreate(scheduler_task, (signed char *)"scheduler",
SCHEDULER_STACK_SIZE, this, SCHEDULER_PRIORITY,
&m_task);
xTaskCreate(delay_cb_task, (signed char *)"delay_cb",
DELAY_CB_STACK_SIZE, this, DELAY_CB_PRIORITY,
&m_delay_cb_task);
}
void SMACCMScheduler::delay(uint16_t ms)
{
/* Wake up the delay callback thread. */
portENTER_CRITICAL();
++g_delay_count;
portEXIT_CRITICAL();
xSemaphoreGive(g_delay_event);
timer_msleep(ms);
/* Put the delay callback thread back to sleep. */
portENTER_CRITICAL();
--g_delay_count;
portEXIT_CRITICAL();
}
uint32_t SMACCMScheduler::millis()
{
return (uint32_t)(timer_get_ticks() / 1000ULL);
}
// XXX this is going to wrap every 1.1 hours
uint32_t SMACCMScheduler::micros()
{
return (uint32_t)timer_get_ticks();
}
void SMACCMScheduler::delay_microseconds(uint16_t us)
{
timer_usleep(us);
}
void SMACCMScheduler::register_delay_callback(AP_HAL::Proc k, uint16_t)
{
m_delay_cb = k;
}
void SMACCMScheduler::register_timer_process(AP_HAL::TimedProc k)
{
for (int i = 0; i < m_num_procs; ++i) {
if (m_procs[i] == k)
return;
}
if (m_num_procs < SMACCM_SCHEDULER_MAX_TIMER_PROCS) {
portENTER_CRITICAL();
m_procs[m_num_procs] = k;
++m_num_procs;
portEXIT_CRITICAL();
}
}
void SMACCMScheduler::register_timer_failsafe(AP_HAL::TimedProc k, uint32_t)
{
m_failsafe_cb = k;
}
void SMACCMScheduler::suspend_timer_procs()
{
xSemaphoreTakeRecursive(g_atomic, portMAX_DELAY);
}
void SMACCMScheduler::resume_timer_procs()
{
xSemaphoreGiveRecursive(g_atomic);
}
void SMACCMScheduler::begin_atomic()
{
}
void SMACCMScheduler::end_atomic()
{
}
void SMACCMScheduler::panic(const prog_char_t *errormsg)
{
hal.console->println_P(errormsg);
// Try to grab "g_atomic" to suspend timer processes, but with a
// timeout in case a timer proc is locked up.
xSemaphoreTakeRecursive(g_atomic, 10);
for(;;)
;
}
void SMACCMScheduler::reboot()
{
for(;;)
;
}
void SMACCMScheduler::run_callbacks()
{
uint32_t now = micros();
// Run timer processes if not suspended.
portENTER_CRITICAL();
uint8_t num_procs = m_num_procs;
portEXIT_CRITICAL();
for (int i = 0; i < num_procs; ++i) {
if (m_procs[i] != NULL) {
m_procs[i](now);
}
}
}
void SMACCMScheduler::run_failsafe_cb()
{
if (m_failsafe_cb)
m_failsafe_cb(micros());
}
void SMACCMScheduler::run_delay_cb()
{
if (m_delay_cb)
m_delay_cb();
}
/** Return true if in the context of a timer process. */
bool SMACCMScheduler::in_timerprocess()
{
return (xTaskGetCurrentTaskHandle() == m_task);
}
/** Return true if the system is initializing. */
bool SMACCMScheduler::system_initializing()
{
return m_initializing;
}
/** Set the system initializing flag to false. */
void SMACCMScheduler::system_initialized()
{
m_initializing = false;
}
#endif // CONFIG_HAL_BOARD == HAL_BOARD_SMACCM