RIOT/core/hwtimer.c

/**
 * hardware timer abstraction
 *
 * Copyright (C) 2013 Freie Universität Berlin
 *
 * This file subject to the terms and conditions of the GNU Lesser General
 * Public License. See the file LICENSE in the top level directory for more
 * details.
 *
 * @ingroup kernel
 * @{
 * @file
 * @author      Heiko Will <hwill@inf.fu-berlin.de>
 * @author      Thomas Hillebrandt <hillebra@inf.fu-berlin.de>
 * @author      Kaspar Schleiser <kaspar.schleiser@fu-berlin.de>
 * @}
 */

#include <stdio.h>
#include <hwtimer.h>
#include <hwtimer_cpu.h>
#include <hwtimer_arch.h>

#include <kernel.h>
#include <thread.h>
#include <lifo.h>

/*---------------------------------------------------------------------------*/

typedef struct hwtimer_t {
    void (*callback)(void*);
    void* data;
} hwtimer_t;

static hwtimer_t timer[ARCH_MAXTIMERS];
static int lifo[ARCH_MAXTIMERS+1];

/*---------------------------------------------------------------------------*/

static void multiplexer(int source) {
//    printf("\nhwt: trigger %i.\n", source);
    lifo_insert(lifo, source);
    lpm_prevent_sleep--;

    timer[source].callback(timer[source].data);
}

static void hwtimer_wakeup(void* ptr) {
    int pid = (int)ptr;
    thread_wakeup(pid);
}

void hwtimer_spin(unsigned long ticks)
{
    unsigned long co = hwtimer_arch_now() + ticks;
    while (hwtimer_arch_now() > co);
    while (hwtimer_arch_now() < co);
}

/*---------------------------------------------------------------------------*/

void hwtimer_init(void) {
    hwtimer_init_comp(F_CPU);
}

/*---------------------------------------------------------------------------*/

void hwtimer_init_comp(uint32_t fcpu) {
    hwtimer_arch_init(multiplexer, fcpu);
    
    lifo_init(lifo, ARCH_MAXTIMERS);
    for (int i = 0; i < ARCH_MAXTIMERS; i++) {
        lifo_insert(lifo, i);
    }
}

/*---------------------------------------------------------------------------*/

int hwtimer_active(void) {
    return (! lifo_empty(lifo));
}

/*---------------------------------------------------------------------------*/

unsigned long hwtimer_now(void)
{
    return hwtimer_arch_now();
}

/*---------------------------------------------------------------------------*/

void hwtimer_wait(unsigned long ticks)
{
    if (ticks <= 6 || inISR()) {
        hwtimer_spin(ticks);
        return;
    }
    
    /* -2 is to adjust the real value */
    int res = hwtimer_set(ticks-2, hwtimer_wakeup, (void*) (unsigned int)(active_thread->pid));
    if (res == -1) {
        hwtimer_spin(ticks);
        return;
    }

    thread_sleep();
}

/*---------------------------------------------------------------------------*/


static int _hwtimer_set(unsigned long offset, void (*callback)(void*), void *ptr, bool absolute)
{
    if (!inISR()) {
        dINT();
    }

    int n = lifo_get(lifo);
    if (n == -1) {
        if (! inISR()) {
            eINT();
        }
        puts("No hwtimer left.");
        return -1;
    }
    
    timer[n].callback = callback;
    timer[n].data = ptr;

    if (absolute) {
//        printf("hwt: setting %i to %u\n", n, offset);
        hwtimer_arch_set_absolute(offset, n);
    }
    else {
//        printf("hwt: setting %i to offset %u\n", n, offset);
        hwtimer_arch_set(offset, n);
    }

    lpm_prevent_sleep++;

    if (!inISR()) {
        eINT();
    }
    return n;
}

int hwtimer_set(unsigned long offset, void (*callback)(void*), void *ptr) {
    return _hwtimer_set(offset, callback, ptr, false);
}

int hwtimer_set_absolute(unsigned long offset, void (*callback)(void*), void *ptr) {
    return _hwtimer_set(offset, callback, ptr, true);
}


/*---------------------------------------------------------------------------*/

int hwtimer_remove(int n)
{
//    printf("hwt: remove %i.\n", n);
    hwtimer_arch_disable_interrupt();
    hwtimer_arch_unset(n);

    lifo_insert(lifo, n);
    timer[n].callback = NULL;

    lpm_prevent_sleep--;
    
    hwtimer_arch_enable_interrupt();
    return 1;
}