kern_et.c

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/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2010-2013 Alexander Motin <mav@FreeBSD.org>
 * 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,
 *    without modification, immediately at the beginning of the file.
 * 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 ``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 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/queue.h>
#include <sys/timeet.h>
 
SLIST_HEAD(et_eventtimers_list, eventtimer);
static struct et_eventtimers_list eventtimers = SLIST_HEAD_INITIALIZER(et_eventtimers);
 
struct mtx      et_eventtimers_mtx;
MTX_SYSINIT(et_eventtimers_init, &et_eventtimers_mtx, "et_mtx", MTX_DEF);
 
SYSCTL_NODE(_kern, OID_AUTO, eventtimer, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "Event timers");
static SYSCTL_NODE(_kern_eventtimer, OID_AUTO, et,
    CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "");
 
/*
 * Register a new event timer hardware.
 */
int
et_register(struct eventtimer *et)
{
        struct eventtimer *tmp, *next;
 
        if (et->et_quality >= 0 || bootverbose) {
                if (et->et_frequency == 0) {
                        printf("Event timer \"%s\" quality %d\n",
                            et->et_name, et->et_quality);
                } else {
                        printf("Event timer \"%s\" "
                            "frequency %ju Hz quality %d\n",
                            et->et_name, (uintmax_t)et->et_frequency,
                            et->et_quality);
                }
        }
        KASSERT(et->et_start, ("et_register: timer has no start function"));
        et->et_sysctl = SYSCTL_ADD_NODE_WITH_LABEL(NULL,
            SYSCTL_STATIC_CHILDREN(_kern_eventtimer_et), OID_AUTO, et->et_name,
            CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
            "event timer description", "eventtimer");
        SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
            "flags", CTLFLAG_RD, &(et->et_flags), 0,
            "Event timer capabilities");
        SYSCTL_ADD_UQUAD(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
            "frequency", CTLFLAG_RD, &(et->et_frequency),
            "Event timer base frequency");
        SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(et->et_sysctl), OID_AUTO,
            "quality", CTLFLAG_RD, &(et->et_quality), 0,
            "Goodness of event timer");
        ET_LOCK();
        if (SLIST_EMPTY(&eventtimers) ||
            SLIST_FIRST(&eventtimers)->et_quality < et->et_quality) {
                SLIST_INSERT_HEAD(&eventtimers, et, et_all);
        } else {
                SLIST_FOREACH(tmp, &eventtimers, et_all) {
                        next = SLIST_NEXT(tmp, et_all);
                        if (next == NULL || next->et_quality < et->et_quality) {
                                SLIST_INSERT_AFTER(tmp, et, et_all);
                                break;
                        }
                }
        }
        ET_UNLOCK();
        return (0);
}
 
/*
 * Deregister event timer hardware.
 */
int
et_deregister(struct eventtimer *et)
{
        int err = 0;
 
        if (et->et_deregister_cb != NULL) {
                if ((err = et->et_deregister_cb(et, et->et_arg)) != 0)
                        return (err);
        }
 
        ET_LOCK();
        SLIST_REMOVE(&eventtimers, et, eventtimer, et_all);
        ET_UNLOCK();
        sysctl_remove_oid(et->et_sysctl, 1, 1);
        return (0);
}
 
/*
 * Change the frequency of the given timer.  If it is the active timer,
 * reconfigure it on all CPUs (reschedules all current events based on the new
 * timer frequency).
 */
void
et_change_frequency(struct eventtimer *et, uint64_t newfreq)
{
 
        cpu_et_frequency(et, newfreq);
}
 
/*
 * Find free event timer hardware with specified parameters.
 */
struct eventtimer *
et_find(const char *name, int check, int want)
{
        struct eventtimer *et = NULL;
 
        SLIST_FOREACH(et, &eventtimers, et_all) {
                if (et->et_active)
                        continue;
                if (name != NULL && strcasecmp(et->et_name, name) != 0)
                        continue;
                if (name == NULL && et->et_quality < 0)
                        continue;
                if ((et->et_flags & check) != want)
                        continue;
                break;
        }
        return (et);
}
 
/*
 * Initialize event timer hardware. Set callbacks.
 */
int
et_init(struct eventtimer *et, et_event_cb_t *event,
    et_deregister_cb_t *deregister, void *arg)
{
 
        if (event == NULL)
                return (EINVAL);
        if (et->et_active)
                return (EBUSY);
 
        et->et_active = 1;
        et->et_event_cb = event;
        et->et_deregister_cb = deregister;
        et->et_arg = arg;
        return (0);
}
 
/*
 * Start event timer hardware.
 * first - delay before first tick.
 * period - period of subsequent periodic ticks.
 */
int
et_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
{
 
        if (!et->et_active)
                return (ENXIO);
        KASSERT(period >= 0, ("et_start: negative period"));
        KASSERT((et->et_flags & ET_FLAGS_PERIODIC) || period == 0,
                ("et_start: period specified for oneshot-only timer"));
        KASSERT((et->et_flags & ET_FLAGS_ONESHOT) || period != 0,
                ("et_start: period not specified for periodic-only timer"));
        if (period != 0) {
                if (period < et->et_min_period)
                        period = et->et_min_period;
                else if (period > et->et_max_period)
                        period = et->et_max_period;
        }
        if (period == 0 || first != 0) {
                if (first < et->et_min_period)
                        first = et->et_min_period;
                else if (first > et->et_max_period)
                        first = et->et_max_period;
        }
        return (et->et_start(et, first, period));
}
 
/* Stop event timer hardware. */
int
et_stop(struct eventtimer *et)
{
 
        if (!et->et_active)
                return (ENXIO);
        if (et->et_stop)
                return (et->et_stop(et));
        return (0);
}
 
/* Mark event timer hardware as broken. */
int
et_ban(struct eventtimer *et)
{
 
        et->et_flags &= ~(ET_FLAGS_PERIODIC | ET_FLAGS_ONESHOT);
        return (0);
}
 
/* Free event timer hardware. */
int
et_free(struct eventtimer *et)
{
 
        if (!et->et_active)
                return (ENXIO);
 
        et->et_active = 0;
        return (0);
}
 
/* Report list of supported event timer hardware via sysctl. */
static int
sysctl_kern_eventtimer_choice(SYSCTL_HANDLER_ARGS)
{
        struct sbuf sb;
        struct eventtimer *et;
        int error;
 
        sbuf_new(&sb, NULL, 256, SBUF_AUTOEXTEND | SBUF_INCLUDENUL);
 
        ET_LOCK();
        SLIST_FOREACH(et, &eventtimers, et_all) {
                if (et != SLIST_FIRST(&eventtimers))
                        sbuf_putc(&sb, ' ');
                sbuf_printf(&sb, "%s(%d)", et->et_name, et->et_quality);
        }
        ET_UNLOCK();
 
        error = sbuf_finish(&sb);
        if (error == 0)
                error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
        sbuf_delete(&sb);
        return (error);
}
SYSCTL_PROC(_kern_eventtimer, OID_AUTO, choice,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
    0, 0, sysctl_kern_eventtimer_choice, "A", "Present event timers");