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TEST = led-test short-test uart-test fmc-test fmc-perf fmc-probe rtc-test

all: $(TEST:=.elf)

%.elf: %.o $(BOARD_OBJS) $(LIBS)
	$(CC) $(CFLAGS) $^ -o $@ -T$(LDSCRIPT) -g -Wl,-Map=$*.map
	$(OBJCOPY) -O ihex $*.elf $*.hex
	$(OBJCOPY) -O binary $*.elf $*.bin
	$(OBJDUMP) -St $*.elf >$*.lst
	$(SIZE) $*.elf

clean:
	rm -f *.o
	rm -f *.elf
	rm -f *.hex
	rm -f *.bin
	rm -f *.map
	rm -f *.lst
' href='#n324'>324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404
/*
 * task.c
 * ----------------
 * Simple cooperative tasking system.
 *
 * Copyright (c) 2017, NORDUnet A/S All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the NORDUnet nor the names of its contributors may
 *   be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* Dead-simple fully-cooperative tasker. There are no priorities; tasks
 * are run in a strictly round-robin fashion. There is no preemption;
 * tasks explicitly yield control. Tasks are created at system init time,
 * and are expected to run an infinite loop; tasks do not return, nor are
 * tasks deleted.
 */

#include "stm-init.h"
#include "task.h"

/* Task Control Block. The structure is private, in case we want to change
 * it later without having to change the API. In any case, external code
 * shouldn't poke its fingers in the internal details.
 */
struct task_cb {
    struct task_cb *next;
    task_state_t state;

    char *name;
    funcp_t func;
    void *cookie;

    void *stack_base;
    size_t stack_len;
    void *stack_ptr;
};

/* Number of tasks. Default is number of RPC dispatch tasks, plus CLI task. */
#ifndef MAX_TASK
#ifdef NUM_RPC_TASK
#define MAX_TASK (NUM_RPC_TASK + 2)
#else
#define MAX_TASK 6
#endif
#endif

static tcb_t tcbs[MAX_TASK];
static size_t num_task = 0;

/* We have a circular list of tasks. New tasks are added at the tail, and
 * tail->next is the head.
 */
static tcb_t *tail = NULL;

/* Currently running task */
static tcb_t *cur_task = NULL;

#define STACK_GUARD_WORD 0x55AA5A5A

#ifdef TASK_METRICS
static uint32_t tick_start = 0;
static uint32_t tick_prev  = 0;
static uint32_t tick_idle  = 0;
static uint32_t tick_max   = 0;
static uint32_t nyield     = 0;
#endif

/* Add a task.
 */
tcb_t *task_add(char *name, funcp_t func, void *cookie, void *stack, size_t stack_len)
{
    if (num_task >= MAX_TASK)
        return NULL;

    if (name == NULL || func == NULL || stack == NULL)
        return NULL;

    tcb_t *t = &tcbs[num_task++];
    t->state = TASK_INIT;

    t->name = name;
    t->func = func;
    t->cookie = cookie;

    t->stack_base = stack;
    t->stack_len = stack_len;
    t->stack_ptr = stack + stack_len;

    for (uint32_t *p = (uint32_t *)t->stack_base; p < (uint32_t *)t->stack_ptr; ++p)
        *p = STACK_GUARD_WORD;

    if (tail == NULL) {
        /* Empty list; initialize it to this task. */
        t->next = t;
    }
    else {
        /* Otherwise insert at the end of the list. */
        t->next = tail->next;
        tail->next = t;
    }
    tail = t;

    return t;
}

/* Set the idle hook function pointer.
 *
 * This function is called repeatedly when the system is idle (there are
 * no runnable tasks).
 *
 * The idle function should NOT call task_delay or HAL_Delay, because that
 * will cause fatal recursion. We could add a recursion guard to
 * task_yield, but we're not currently using the idle hook, and I'm
 * thinking about removing it entirely.
 */
static void default_idle_hook(void) { }
static funcp_t idle_hook = default_idle_hook;
void task_set_idle_hook(funcp_t func)
{
    idle_hook = (func == NULL) ? default_idle_hook : func;
}

/* Find the next runnable task.
 */
static tcb_t *next_task(void)
{
    tcb_t *t;

    /* If the tasker isn't running yet, return the first task. */
    if (cur_task == NULL)
        return (tail == NULL) ? NULL : tail->next;

    // XXX critical section?

    /* find the next runnable task */
    for (t = cur_task->next; t != cur_task; t = t->next) {
        if (t->state != TASK_WAITING)
            return t;
    }

    /* searched all the way back to cur_task - is it runnable? */
    return (cur_task->state == TASK_WAITING) ? NULL : cur_task;
}

/* Check for stack overruns.
 */
static void check_stack(tcb_t *t)
{
    if (t->stack_ptr < t->stack_base ||
        t->stack_ptr >= t->stack_base + t->stack_len ||
        *(uint32_t *)t->stack_base != STACK_GUARD_WORD)
        Error_Handler();
}

/* Yield control to the next runnable task.
 */
void task_yield(void)
{
    tcb_t *next;

    /* If there are no defined tasks, exit immediately so we don't get
     * caught in the idle loop.
     */
    if (tail == NULL)
	return;

#ifdef TASK_METRICS
    uint32_t tick0 = HAL_GetTick();
#endif

    /* Find the next runnable task. Loop if every task is waiting. */
    while (1) {
        next = next_task();
        if (next == NULL)
            idle_hook();
        else
            break;
    }

    /* If we decide we don't need the idle hook, the preceding loop could
     * devolve to something like this:
     *
     * do {
     *     next = next_task();
     * } while (next == NULL);
     */

#ifdef TASK_METRICS
    uint32_t tick = HAL_GetTick();
    tick_idle += (tick - tick0);
    if (tick_start == 0)
        tick_start = tick;
    if (tick_prev != 0) {
        uint32_t duration = tick0 - tick_prev;
        if (duration > tick_max)
            tick_max = duration;
    }
    tick_prev = tick;
    ++nyield;
#endif

    /* If there are no other runnable tasks (and cur_task is runnable),
     * we don't need to context-switch.
     */
    if (next == cur_task)
        return;

    /* Save current context, if there is one. */
    if (cur_task != NULL) {
        __asm("push {r0-r12, lr}");
        cur_task->stack_ptr = (void *)__get_MSP();

        /* Check for stack overruns. */
        check_stack(cur_task);
    }

    cur_task = next;

    /* If task is in init state, call its entry point. */
    if (cur_task->state == TASK_INIT) {
        __set_MSP((uint32_t)cur_task->stack_ptr);
        cur_task->state = TASK_READY;
        cur_task->func();
        /*NOTREACHED*/
    }

    /* Otherwise, restore the task's context. */
    else {
        __set_MSP((uint32_t)cur_task->stack_ptr);
        __asm("pop {r0-r12, lr}");
        return;
    }
}

/* Put the current task to sleep (make it non-runnable).
 */
void task_sleep(void)
{
    if (cur_task != NULL)
        cur_task->state = TASK_WAITING;

    task_yield();
}

/* Wake a task (make it runnable).
 */
void task_wake(tcb_t *t)
{
    if (t != NULL)
        t->state = TASK_READY;
}

/* Accessor functions */

tcb_t *task_get_tcb(void)
{
    return cur_task;
}

char *task_get_name(tcb_t *t)
{
    if (t == NULL)
        t = cur_task;

    return t->name;
}

funcp_t task_get_func(tcb_t *t)
{
    if (t == NULL)
        t = cur_task;

    return t->func;
}

void *task_get_cookie(tcb_t *t)
{
    if (t == NULL)
        t = cur_task;

    return t->cookie;
}

task_state_t task_get_state(tcb_t *t)
{
    if (t == NULL)
        t = cur_task;

    return t->state;
}

void *task_get_stack(tcb_t *t)
{
    if (t == NULL)
        t = cur_task;

    return t->stack_ptr;
}

/* stupid linear search for first non guard word */
size_t task_get_stack_highwater(tcb_t *t)
{
    if (t == NULL)
        t = cur_task;

    const uint32_t * const b = (uint32_t *)t->stack_base;

    for (size_t i = 0; i < t->stack_len/4; ++i) {
        if (b[i] != STACK_GUARD_WORD) {
            return (t->stack_len - (i * 4));
        }
    }

    return 0;
}    

/* Iterate through tasks.
 *
 * Returns the next task control block, or NULL at the end of the list.
 */
tcb_t *task_iterate(tcb_t *t)
{
    if (t == NULL)
        return (tail == NULL) ? NULL : tail->next;

    if (t == tail)
        return NULL;

    return t->next;
}

/* Delay a number of 1ms ticks.
 */
void task_delay(uint32_t delay)
{
    uint32_t tickstart = HAL_GetTick();

    while ((HAL_GetTick() - tickstart) < delay)
	task_yield();
}
void HAL_Delay(uint32_t delay) __attribute__((alias("task_delay")));

/* Simple mutex-like locks. A real mutex would require the unlocker to be
 * the current owner, but then we have to define and return errors, when
 * all we want at the moment is simple mutual exclusion.
 */
void task_mutex_lock(task_mutex_t *mutex)
{
    while (mutex->locked)
	task_yield();
    mutex->locked = 1;
}

void task_mutex_unlock(task_mutex_t *mutex)
{
    if (mutex != NULL)
	mutex->locked = 0;
}

#ifdef TASK_METRICS
void task_get_metrics(struct task_metrics *tm)
{
    if (tm != NULL) {
        tm->avg.tv_sec  = 0;
        tm->avg.tv_usec = (HAL_GetTick() - tick_start - tick_idle) * 1000 / nyield;
        if (tm->avg.tv_usec > 1000000) {
            tm->avg.tv_sec  = tm->avg.tv_usec / 1000000;
            tm->avg.tv_usec = tm->avg.tv_usec % 1000000;
        }
        tm->max.tv_sec  = tick_max / 1000;
        tm->max.tv_usec = (tick_max % 1000) * 1000;
    }
}

void task_reset_metrics(void)
{
    tick_start = HAL_GetTick();
    tick_prev = tick_idle = tick_max = nyield = 0;
}
#endif