/*      $NetBSD: config_hook.c,v 1.12 2020/11/21 21:08:32 thorpej Exp $ */

/*-
 * Copyright (c) 1999-2001
 *         Shin Takemura and PocketBSD Project. 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 the PocketBSD project
 *      and its contributors.
 * 4. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: config_hook.c,v 1.12 2020/11/21 21:08:32 thorpej Exp $");

#include <sys/param.h>
#include <sys/device.h>
#include <sys/kmem.h>
#include <sys/systm.h>
#include <sys/kernel.h>

#include <machine/config_hook.h>

struct hook_rec {
        TAILQ_ENTRY(hook_rec) hr_link;
        void *hr_ctx;
        int hr_type;
        long hr_id;
        enum config_hook_mode hr_mode;
        int (*hr_func)(void *, int, long, void *);
};

TAILQ_HEAD(hook_list, hook_rec);
struct hook_list hook_lists[CONFIG_HOOK_NTYPES];
struct hook_list call_list;

void
config_hook_init(void)
{
        int i;

        for (i = 0; i < CONFIG_HOOK_NTYPES; i++) {
                TAILQ_INIT(&hook_lists[i]);
        }
        TAILQ_INIT(&call_list);
}

config_hook_tag
config_hook(int type, long id, enum config_hook_mode mode,
    int (*func)(void *, int, long, void *), void *ctx)
{
        struct hook_rec *hr, *cr, *prev_hr;
        int s;

        /* check type value */
        if (type < 0 || CONFIG_HOOK_NTYPES <= type) {
                panic("config_hook: invalid hook type");
        }

        /* check mode compatibility */
        prev_hr = NULL;
        TAILQ_FOREACH(hr, &hook_lists[type], hr_link) {
                if (hr->hr_id == id) {
                        if (hr->hr_mode != mode) {
                                panic("config_hook: incompatible mode on "
                                    "type=%d/id=%ld != %d",
                                    type, id, hr->hr_mode);
                        }
                        prev_hr = hr;
                }
        }
        switch (mode) {
        case CONFIG_HOOK_SHARE:
                /* nothing to do */
                break;
        case CONFIG_HOOK_REPLACE:
                if (prev_hr != NULL) {
                        printf("config_hook: type=%d/id=%ld is replaced",
                            type, id);
                        s = splhigh();
                        TAILQ_REMOVE(&hook_lists[type], prev_hr, hr_link);
                        TAILQ_NEXT(prev_hr, hr_link) = NULL;
                        splx(s);
                }
                break;
        case CONFIG_HOOK_EXCLUSIVE:
                if (prev_hr != NULL) {
                        panic("config_hook: type=%d/id=%ld is already "
                            "hooked(%p)", type, id, prev_hr);
                }
                break;
        default:
                break;
        }

        /* allocate new record */
        hr = kmem_alloc(sizeof(*hr), KM_SLEEP);
        hr->hr_ctx = ctx;
        hr->hr_type = type;
        hr->hr_id = id;
        hr->hr_func = func;
        hr->hr_mode = mode;

        s = splhigh();
        TAILQ_INSERT_HEAD(&hook_lists[type], hr, hr_link);

        /* update call list */
        TAILQ_FOREACH(cr, &call_list, hr_link) {
                if (cr->hr_type == type && cr->hr_id == id) {
                        if (cr->hr_func != NULL &&
                            cr->hr_mode != mode) {
                                panic("config_hook: incompatible mode on "
                                    "type=%d/id=%ld != %d",
                                    type, id, cr->hr_mode);
                        }
                        cr->hr_ctx = ctx;
                        cr->hr_func = func;
                        cr->hr_mode = mode;
                }
        }
        splx(s);

        return (hr);
}

void
config_unhook(config_hook_tag hrx)
{
        int s;
        struct hook_rec *hr = (struct hook_rec*)hrx, *cr;

        if (TAILQ_NEXT(hr, hr_link) != NULL) {
                s = splhigh();
                TAILQ_REMOVE(&hook_lists[hr->hr_type], hr, hr_link);
                TAILQ_NEXT(hr, hr_link) = NULL;
                /* update call list */
                TAILQ_FOREACH(cr, &call_list, hr_link) {
                        if (cr->hr_type == hr->hr_type &&
                            cr->hr_id == hr->hr_id)
                                cr->hr_func = NULL;
                }
                splx(s);
        }
        kmem_free(hr, sizeof(*hr));
}

int
__config_hook_call(int type, long id, void *msg, int reverse)
{
        int res;
        struct hook_rec *hr;

        /* Check type value. */
        if (type < 0 || CONFIG_HOOK_NTYPES <= type) {
                panic("config_hook: invalid hook type");
        }

        res = -1;
        if (reverse) {
                TAILQ_FOREACH_REVERSE(hr, &hook_lists[type], hook_list,
                    hr_link) {
                        if (hr->hr_id == id)
                                res = (*hr->hr_func)(hr->hr_ctx, type, id,msg);
                }
        } else {
                TAILQ_FOREACH(hr, &hook_lists[type], hr_link) {
                        if (hr->hr_id == id)
                                res = (*hr->hr_func)(hr->hr_ctx, type, id,msg);
                }
        }

        return (res);
}

config_hook_tag
config_connect(int type, long id)
{
        int s;
        struct hook_rec *cr, *hr;

        /* check type value */
        if (type < 0 || CONFIG_HOOK_NTYPES <= type) {
                panic("config_hook: invalid hook type");
        }

        /* allocate new record */
        cr = kmem_alloc(sizeof(*hr), KM_SLEEP);
        cr->hr_func = NULL;
        cr->hr_type = type;
        cr->hr_id = id;

        s = splhigh();
        /* insert the record into the call list */
        TAILQ_INSERT_HEAD(&call_list, cr, hr_link);

        /* scan hook list */
        TAILQ_FOREACH(hr, &hook_lists[type], hr_link) {
                if (hr->hr_id == id) {
                        if (hr->hr_mode == CONFIG_HOOK_SHARE)
                                panic("config_connect: can't connect with "
                                    "shared hook, type=%d id=%ld", type, id);
                        cr->hr_ctx = hr->hr_ctx;
                        cr->hr_func = hr->hr_func;
                        cr->hr_mode = hr->hr_mode;
                }
        }
        splx(s);

        return (cr);
}

void
config_disconnect(config_call_tag crx)
{
        int s;
        struct hook_rec *cr = (struct hook_rec*)crx;

        s = splhigh();
        TAILQ_REMOVE(&call_list, cr, hr_link);
        splx(s);

        kmem_free(cr, sizeof(*cr));
}

int
config_connected_call(config_call_tag crx, void *msg)
{
        int res;
        struct hook_rec *cr = (struct hook_rec*)crx;

        if (cr->hr_func != NULL)
                res = (*cr->hr_func)(cr->hr_ctx, cr->hr_type, cr->hr_id, msg);
        else
                res = -1;

        return (res);
}