/*
 * Copyright (c) 1996, 1997
 *      HD Associates, Inc.  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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by HD Associates, Inc
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES 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 HD ASSOCIATES 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.
 *
 * $FreeBSD: src/sys/posix4/ksched.c,v 1.7.2.1 2000/05/16 06:58:13 dillon Exp $
 */

/*
 * ksched: Soft real time scheduling based on "rtprio".
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/posix4.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/resource.h>
#include <machine/cpu.h>        /* For need_user_resched */


/* ksched: Real-time extension to support POSIX priority scheduling.
 */

struct ksched {
        struct timespec rr_interval;
};

int
ksched_attach(struct ksched **p)
{
        struct ksched *ksched;

        ksched = kmalloc(sizeof(*ksched), M_P31B, M_WAITOK);

        ksched->rr_interval.tv_sec = 0;
        ksched->rr_interval.tv_nsec = 1000000000L / 10; /* XXX */

        *p = ksched;
        return 0;
}

int
ksched_detach(struct ksched *p)
{
        kfree(p, M_P31B);

        return 0;
}

/*
 * XXX About priorities
 *
 *      POSIX 1003.1b requires that numerically higher priorities be of
 *      higher priority.  It also permits sched_setparam to be
 *      implementation defined for SCHED_OTHER.  I don't like
 *      the notion of inverted priorites for normal processes when
 *      you can use "setpriority" for that.
 *
 *      I'm rejecting sched_setparam for SCHED_OTHER with EINVAL.
 */

/* Macros to convert between the unix (lower numerically is higher priority)
 * and POSIX 1003.1b (higher numerically is higher priority)
 */

#define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
#define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))

/*
 * These improve readability a bit for me:
 */
#define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
#define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)

static __inline int
getscheduler(register_t *ret, struct ksched *ksched, struct lwp *lp)
{
        int e = 0;

        switch (lp->lwp_rtprio.type) {
        case RTP_PRIO_FIFO:
                *ret = SCHED_FIFO;
                break;
        case RTP_PRIO_REALTIME:
                *ret = SCHED_RR;
                break;
        default:
                *ret = SCHED_OTHER;
                break;
        }

        return e;
}

int
ksched_setparam(register_t *ret, struct ksched *ksched,
    struct lwp *lp, const struct sched_param *param)
{
        register_t policy;
        int e;

        e = getscheduler(&policy, ksched, lp);

        if (e == 0) {
                if (policy == SCHED_OTHER)
                        e = EINVAL;
                else
                        e = ksched_setscheduler(ret, ksched, lp, policy, param);
        }

        return e;
}

int
ksched_getparam(register_t *ret, struct ksched *ksched,
    struct lwp *lp, struct sched_param *param)
{
        if (RTP_PRIO_IS_REALTIME(lp->lwp_rtprio.type))
                param->sched_priority = rtpprio_to_p4prio(lp->lwp_rtprio.prio);

        return 0;
}

/*
 * XXX The priority and scheduler modifications should
 *     be moved into published interfaces in kern/kern_sync.
 *
 * The permissions to modify process p were checked in "p31b_proc()".
 *
 */
int
ksched_setscheduler(register_t *ret, struct ksched *ksched,
    struct lwp *lp, int policy, const struct sched_param *param)
{
        int e = 0;
        struct rtprio rtp;

        switch(policy) {
        case SCHED_RR:
        case SCHED_FIFO:
                if (param->sched_priority >= P1B_PRIO_MIN &&
                    param->sched_priority <= P1B_PRIO_MAX) {
                        rtp.prio = p4prio_to_rtpprio(param->sched_priority);
                        rtp.type = (policy == SCHED_FIFO) ?
                            RTP_PRIO_FIFO : RTP_PRIO_REALTIME;

                        lp->lwp_rtprio = rtp;
                        need_user_resched();
                } else {
                        e = EINVAL;
                }
                break;
        case SCHED_OTHER:
                rtp.type = RTP_PRIO_NORMAL;
                rtp.prio = p4prio_to_rtpprio(param->sched_priority);
                lp->lwp_rtprio = rtp;

                /*
                 * XXX Simply revert to whatever we had for last
                 *     normal scheduler priorities.
                 *     This puts a requirement
                 *     on the scheduling code: You must leave the
                 *     scheduling info alone.
                 */
                need_user_resched();
                break;
        }

        return e;
}

int
ksched_getscheduler(register_t *ret, struct ksched *ksched, struct lwp *lp)
{
        return getscheduler(ret, ksched, lp);
}

/*
 * ksched_yield: Yield the CPU.
 *
 * MPSAFE
 */
int
ksched_yield(register_t *ret, struct ksched *ksched)
{
        struct lwp *lp;

        if ((lp = curthread->td_lwp) != NULL)
                lp->lwp_proc->p_usched->yield(lp);
        return 0;
}

/*
 * MPSAFE
 */
int
ksched_get_priority_max(register_t*ret, struct ksched *ksched, int policy)
{
        int e = 0;

        switch (policy) {
        case SCHED_FIFO:
        case SCHED_RR:
                *ret = RTP_PRIO_MAX;
                break;
        case SCHED_OTHER:
                *ret =  PRIO_MAX;
                break;
        default:
                e = EINVAL;
                break;
        }

        return e;
}

/*
 * MPSAFE
 */
int
ksched_get_priority_min(register_t *ret, struct ksched *ksched, int policy)
{
        int e = 0;

        switch (policy) {
        case SCHED_FIFO:
        case SCHED_RR:
                *ret = P1B_PRIO_MIN;
                break;
        case SCHED_OTHER:
                *ret =  PRIO_MIN;
                break;
        default:
                e = EINVAL;
                break;
        }
        return e;
}

/*
 * MPSAFE
 */
int
ksched_rr_get_interval(register_t *ret, struct ksched *ksched,
    struct lwp *lp, struct timespec *timespec)
{
        *timespec = ksched->rr_interval;

        return 0;
}