clock.c

xenomai 很好的linux实时补丁

/*
 * Written by Gilles Chanteperdrix <[e-mail]>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/**
 * @ingroup posix
 * @defgroup posix_time Clocks and timers.
 *
 * Clocks and timers services.
 *
 * Xenomai POSIX skin supports two clocks.
 *
 * CLOCK_REALTIME maps to the nucleus system clock, keeping time as the amount
 * of time since the Epoch, with a resolution of one system clock tick. The
 * duration of the system clock tick depends on the settings of the nucleus
 * (configurable at compile-time with @a CONFIG_XENO_OPT_TIMING_PERIOD, and at
 * run-time with the module parameter @a tick_arg). When the system timer is set
 * to aperiodic mode, the default, the system clock tick is one nanosecond.
 *
 * CLOCK_MONOTONIC maps to an architecture-dependent high resolution counter, so
 * is suitable for measuring short time intervals. However, when used for
 * sleeping (with clock_nanosleep()), the CLOCK_MONOTONIC clock has a resolution
 * of one system clock tick, like the CLOCK_REALTIME clock.
 *
 * Setting any of the two clocks with clock_settime() is currently not
 * supported.
 *
 * Timer objects may be created with the timer_create() service using either of
 * the two clocks, but the resolution of these timers is one system clock tick,
 * as is the case for clock_nanosleep().
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/xsh_chap02_08.html#tag_02_08_05
 *@{*/

#include <posix/thread.h>

/**
 * Get the resolution of the specified clock.
 *
 * This service returns, at the address @a res, if it is not @a NULL, the
 * resolution of the clock @a clock_id.
 *
 * For both CLOCK_REALTIME and CLOCK_MONOTONIC, this resolution is the duration
 * of one system clock tick. No other clock is supported.
 *
 * @param clock_id clock identifier, either CLOCK_REALTIME or CLOCK_MONOTONIC;
 *
 * @param res the address where the resolution of the specified clock will be
 * stored on success.
 *
 * @retval 0 on success;
 * @retval -1 with @a errno set if:
 * - EINVAL, @a clock_id is invalid;
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/clock_getres.html
 * 
 */
int clock_getres (clockid_t clock_id, struct timespec *res)

{
    if (clock_id != CLOCK_MONOTONIC && clock_id != CLOCK_REALTIME)
        {
        thread_set_errno(EINVAL);
        return -1;
        }

    if(res)
        ticks2ts(res, 1);

    return 0;
}

/**
 * Read the specified clock. 
 *
 * This service returns, at the address @a tp the current value of the clock @a
 * clock_id. If @a clock_id is:
 * - CLOCK_REALTIME, the clock value represents the amount of time since the
 *   Epoch, with a precision of one system clock tick;
 * - CLOCK_MONOTONIC, the clock value is given by an architecture-dependent high
 *   resolution counter, with a precision independent from the system clock tick
 *   duration.
 *
 * @param clock_id clock identifier, either CLOCK_REALTIME or CLOCK_MONOTONIC;
 *
 * @param tp the address where the value of the specified clock will be stored.
 *
 * @retval 0 on success;
 * @retval -1 with @a errno set if:
 * - EINVAL, @a clock_id is invalid.
 * 
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/clock_gettime.html
 * 
 */
int clock_gettime (clockid_t clock_id, struct timespec *tp)

{
    xnticks_t cpu_time;

    switch(clock_id)
        {
        case CLOCK_REALTIME:
            ticks2ts(tp, xnpod_get_time());
            break;

        case CLOCK_MONOTONIC:
            cpu_time = xnpod_get_cpu_time();
            tp->tv_sec = xnarch_uldivrem(cpu_time, ONE_BILLION, &tp->tv_nsec);
            break;

        default:
            thread_set_errno(EINVAL);
            return -1;
        }

    return 0;    
}

/**
 * Set the specified clock.
 *
 * This service is not supported.
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/clock_settime.html
 * 
 */
int clock_settime(clockid_t clock_id, const struct timespec *tp)

{
    if (clock_id != CLOCK_REALTIME || (unsigned long) tp->tv_nsec >= ONE_BILLION)
        {
        thread_set_errno(EINVAL);
        return -1;
        }

    thread_set_errno(ENOTSUP);
    return -1;
}

/**
 * Sleep some amount of time.
 *
 * This service suspends the calling thread until the wakeup time specified by
 * @a rqtp, or a signal is delivered to the caller. If the flag TIMER_ABSTIME is
 * set in the @a flags argument, the wakeup time is specified as an absolute
 * value of the clock @a clock_id. If the flag TIMER_ABSTIME is not set, the
 * wakeup time is specified as a time interval.
 *
 * If this service is interrupted by a signal, the flag TIMER_ABSTIME is not
 * set, and @a rmtp is not @a NULL, the time remaining until the specified
 * wakeup time is returned at the address @a rmtp.
 *
 * The resolution of this service is one system clock tick.
 *
 * @param clock_id clock identifier, either CLOCK_REALTIME or CLOCK_MONOTONIC.
 *
 * @param flags one of:
 * - 0 meaning that the wakeup time @a rqtp is a time interval;
 * - TIMER_ABSTIME, meaning that the wakeup time is an absolute value of the
 *   clock @a clock_id.
 *
 * @param rqtp address of the wakeup time.
 *
 * @param rmtp address where the remaining time before wakeup will be stored if
 * the service is interrupted by a signal.
 *
 * @return 0 on success;
 * @return an error number if:
 * - EPERM, the caller context is invalid;
 * - ENOTSUP, the specified clock is unsupported;
 * - EINVAL, the specified wakeup time is invalid;
 * - EINTR, this service was interrupted by a signal.
 *
 * @par Valid contexts:
 * - Xenomai kernel-space thread,
 * - Xenomai user-space thread (switches to primary mode).
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/clock_nanosleep.html
 * 
 */
int clock_nanosleep (clockid_t clock_id,
		     int flags,
		     const struct timespec *rqtp,
		     struct timespec *rmtp)
{
    xnticks_t start, timeout;
    xnthread_t *cur;
    spl_t s;
    int err = 0;

    if (xnpod_unblockable_p())
        return EPERM;

    if (clock_id != CLOCK_MONOTONIC && clock_id != CLOCK_REALTIME)
        return ENOTSUP;
    
    if ((unsigned long) rqtp->tv_nsec >= ONE_BILLION)
        return EINVAL;

    cur = xnpod_current_thread();

    xnlock_get_irqsave(&nklock, s);

    start = clock_get_ticks(clock_id);
    timeout = ts2ticks_ceil(rqtp);

    switch (flags)
	{
	default:
            err = EINVAL;
            goto unlock_and_return;

	case TIMER_ABSTIME:
	    timeout -= start;
            if((xnsticks_t) timeout < 0)
                {
                err = 0;
                goto unlock_and_return;
                }

	    break;

	case 0:
	    break;
	}

    thread_cancellation_point(cur);

    xnpod_suspend_thread(cur, XNDELAY, timeout+1, NULL);

    thread_cancellation_point(cur);

    if (xnthread_test_flags(cur, XNBREAK))
	{
        xnlock_put_irqrestore(&nklock, s);

        if (flags == 0 && rmtp)
            {
            xnsticks_t rem  = timeout - (clock_get_ticks(clock_id) - start);

            ticks2ts(rmtp, rem > 0 ? rem : 0);
            }

        return EINTR;
	}

  unlock_and_return:
    xnlock_put_irqrestore(&nklock, s);
    
    return err;
}

/**
 * Sleep some amount of time.
 *
 * This service suspends the calling thread until the wakeup time specified by
 * @a rqtp, or a signal is delivered. The wakeup time is specified as a time
 * interval.
 *
 * If this service is interrupted by a signal and @a rmtp is not @a NULL, the
 * time remaining until the specified wakeup time is returned at the address @a
 * rmtp.
 *
 * The resolution of this service is one system clock tick.
 *
 * @param rqtp address of the wakeup time.
 *
 * @param rmtp address where the remaining time before wakeup will be stored if
 * the service is interrupted by a signal.
 *
 * @retval 0 on success;
 * @retval -1 with @a errno set if:
 * - EPERM, the caller context is invalid;
 * - EINVAL, the specified wakeup time is invalid;
 * - EINTR, this service was interrupted by a signal.
 *
 * @par Valid contexts:
 * - Xenomai kernel-space thread,
 * - Xenomai user-space thread (switches to primary mode).
 *
 * @see http://www.opengroup.org/onlinepubs/000095399/functions/nanosleep.html
 * 
 */
int nanosleep(const struct timespec *rqtp, struct timespec *rmtp)
{
    int err = clock_nanosleep(CLOCK_REALTIME, 0, rqtp, rmtp);

    if(!err)
        return 0;

    thread_set_errno(err);
    return -1;
}

/*@}*/

EXPORT_SYMBOL(clock_getres);
EXPORT_SYMBOL(clock_gettime);
EXPORT_SYMBOL(clock_settime);
EXPORT_SYMBOL(clock_nanosleep);
EXPORT_SYMBOL(nanosleep);