source: rtems-libbsd/rtemsbsd/src/rtems-bsd-timeout.c @ 8420b94

/**
 * @file
 *
 * @ingroup rtems_bsd_rtems
 *
 * @brief TODO.
 */

/*
 * COPYRIGHT (c) 2012.
 * On-Line Applications Research Corporation (OAR).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

#include <freebsd/machine/rtems-bsd-config.h>
#include <freebsd/sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <freebsd/sys/param.h>
#include <freebsd/sys/systm.h>
#include <freebsd/sys/bus.h>
#include <freebsd/sys/callout.h>
#include <freebsd/sys/condvar.h>
#include <freebsd/sys/interrupt.h>
#include <freebsd/sys/kernel.h>
#include <freebsd/sys/ktr.h>
#include <freebsd/sys/lock.h>
#include <freebsd/sys/malloc.h>
#include <freebsd/sys/mutex.h>
#include <freebsd/sys/proc.h>
#include <freebsd/sys/sdt.h>

static int timeout_cpu;
/*
 * There is one struct callout_cpu per cpu, holding all relevant
 * state for the callout processing thread on the individual CPU.
 * In particular:
 *      cc_ticks is incremented once per tick in callout_cpu().
 *      It tracks the global 'ticks' but in a way that the individual
 *      threads should not worry about races in the order in which
 *      hardclock() and hardclock_cpu() run on the various CPUs.
 *      cc_softclock is advanced in callout_cpu() to point to the
 *      first entry in cc_callwheel that may need handling. In turn,
 *      a softclock() is scheduled so it can serve the various entries i
 *      such that cc_softclock <= i <= cc_ticks .
 *      XXX maybe cc_softclock and cc_ticks should be volatile ?
 *
 *      cc_ticks is also used in callout_reset_cpu() to determine
 *      when the callout should be served.
 */
struct callout_cpu {
        struct mtx              cc_lock;
        struct callout          *cc_callout;
        struct callout_tailq    *cc_callwheel;
        struct callout_list     cc_callfree;
        struct callout          *cc_next;
        struct callout          *cc_curr;
        void                    *cc_cookie;
        int                     cc_ticks;
        int                     cc_softticks;
        int                     cc_cancel;
        int                     cc_waiting;
};

/*
 * timeout --
 *      Execute a function after a specified length of time.
 *
 * untimeout --
 *      Cancel previous timeout function call.
 *
 * callout_handle_init --
 *      Initialize a handle so that using it with untimeout is benign.
 *
 *      See AT&T BCI Driver Reference Manual for specification.  This
 *      implementation differs from that one in that although an 
 *      identification value is returned from timeout, the original
 *      arguments to timeout as well as the identifier are used to
 *      identify entries for untimeout.
 */

struct callout_handle
timeout(ftn, arg, to_ticks)
        timeout_t *ftn;
        void *arg;
        int to_ticks;
{
        struct callout_cpu *cc;
        struct callout *new;
        struct callout_handle handle;

#if 0
        cc = CC_CPU(timeout_cpu);
        CC_LOCK(cc);
        /* Fill in the next free callout structure. */
        new = SLIST_FIRST(&cc->cc_callfree);
        if (new == NULL)
                /* XXX Attempt to malloc first */
                panic("timeout table full");
        SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle);
        callout_reset(new, to_ticks, ftn, arg);
        handle.callout = new;
        CC_UNLOCK(cc);
#endif
        return (handle);
}