/*      $NetBSD: button.c,v 1.15 2021/09/29 15:17:01 thorpej Exp $      */

/*
 * Copyright (c) 2003 Wasabi Systems, Inc.
 * All rights reserved.
 *
 * Written by Jason R. Thorpe for Wasabi Systems, Inc.
 *
 * 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 for the NetBSD Project by
 *      Wasabi Systems, Inc.
 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC
 * 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: button.c,v 1.15 2021/09/29 15:17:01 thorpej Exp $");

#include <sys/param.h>
#include <sys/conf.h>
#include <sys/systm.h>
#include <sys/queue.h>
#include <sys/mutex.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
#include <sys/callout.h>
#include <sys/kernel.h>
#include <sys/once.h>
#include <sys/poll.h>
#include <sys/select.h>
#include <sys/vnode.h>

#include <machine/button.h>

#include <landisk/dev/buttonvar.h>

/*
 * event handler
 */
static LIST_HEAD(, btn_event) btn_event_list;
static kmutex_t btn_event_list_lock;

static struct lwp *btn_daemon;

#define BTN_MAX_EVENTS          32

static kmutex_t btn_event_queue_lock;
static kcondvar_t btn_event_queue_cv;

static button_event_t btn_event_queue[BTN_MAX_EVENTS];
static int btn_event_queue_head;
static int btn_event_queue_tail;
static int btn_event_queue_count;
static int btn_event_queue_flags;
static struct selinfo btn_event_queue_selinfo;

static char btn_type[32];

#define BEVQ_F_WAITING          0x01    /* daemon waiting for event */

#define BTN_NEXT_EVENT(x)       (((x) + 1) / BTN_MAX_EVENTS)

dev_type_open(btnopen);
dev_type_close(btnclose);
dev_type_ioctl(btnioctl);
dev_type_read(btnread);
dev_type_poll(btnpoll);
dev_type_kqfilter(btnkqfilter);

const struct cdevsw button_cdevsw = {
        .d_open = btnopen,
        .d_close = btnclose,
        .d_read = btnread,
        .d_write = nowrite,
        .d_ioctl = btnioctl,
        .d_stop = nostop,
        .d_tty = notty,
        .d_poll = btnpoll,
        .d_mmap = nommap,
        .d_kqfilter = btnkqfilter,
        .d_discard = nodiscard,
        .d_flag = 0
};

int
btn_init(void)
{

        LIST_INIT(&btn_event_list);
        mutex_init(&btn_event_list_lock, MUTEX_DEFAULT, IPL_NONE);
        mutex_init(&btn_event_queue_lock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&btn_event_queue_cv, "btncv");
        selinit(&btn_event_queue_selinfo);

        return 0;
}

static int
btn_queue_event(button_event_t *bev)
{

        if (btn_event_queue_count == BTN_MAX_EVENTS)
                return (0);

        btn_event_queue[btn_event_queue_head] = *bev;
        btn_event_queue_head = BTN_NEXT_EVENT(btn_event_queue_head);
        btn_event_queue_count++;

        return (1);
}

static int
btn_get_event(button_event_t *bev)
{

        if (btn_event_queue_count == 0)
                return (0);

        *bev = btn_event_queue[btn_event_queue_tail];
        btn_event_queue_tail = BTN_NEXT_EVENT(btn_event_queue_tail);
        btn_event_queue_count--;

        return (1);
}

static void
btn_event_queue_flush(void)
{

        btn_event_queue_head = 0;
        btn_event_queue_tail = 0;
        btn_event_queue_count = 0;
        btn_event_queue_flags = 0;
}

int
btnopen(dev_t dev, int flag, int mode, struct lwp *l)
{
        int error;

        if (minor(dev) != 0) {
                return (ENODEV);
        }

        mutex_enter(&btn_event_queue_lock);
        if (btn_daemon != NULL) {
                error = EBUSY;
        } else {
                error = 0;
                btn_daemon = l;
                btn_event_queue_flush();
        }
        mutex_exit(&btn_event_queue_lock);

        return (error);
}

int
btnclose(dev_t dev, int flag, int mode, struct lwp *l)
{
        int count;

        if (minor(dev) != 0) {
                return (ENODEV);
        }

        mutex_enter(&btn_event_queue_lock);
        count = btn_event_queue_count;
        btn_daemon = NULL;
        btn_event_queue_flush();
        mutex_exit(&btn_event_queue_lock);

        if (count) {
                printf("WARNING: %d events lost by exiting daemon\n", count);
        }

        return (0);
}

int
btnioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
{
        int error = 0;

        if (minor(dev) != 0) {
                return (ENODEV);
        }

        switch (cmd) {
        case BUTTON_IOC_GET_TYPE:
            {
                struct button_type *button_type = (void *)data;
                strcpy(button_type->button_type, btn_type);
                break;
            }

        default:
                error = ENOTTY;
                break;
        }

        return (error);
}

int
btnread(dev_t dev, struct uio *uio, int flags)
{
        button_event_t bev;
        int error;

        if (minor(dev) != 0) {
                return (ENODEV);
        }

        if (uio->uio_resid != BUTTON_EVENT_MSG_SIZE) {
                return (EINVAL);
        }

        mutex_enter(&btn_event_queue_lock);
        for (;;) {
                if (btn_get_event(&bev)) {
                        mutex_exit(&btn_event_queue_lock);
                        return (uiomove(&bev, BUTTON_EVENT_MSG_SIZE, uio));
                }

                if (flags & IO_NDELAY) {
                        mutex_exit(&btn_event_queue_lock);
                        return (EWOULDBLOCK);
                }

                btn_event_queue_flags |= BEVQ_F_WAITING;
                error = cv_wait_sig(&btn_event_queue_cv, &btn_event_queue_lock);
                if (error) {
                        mutex_exit(&btn_event_queue_lock);
                        return (error);
                }
        }
}

int
btnpoll(dev_t dev, int events, struct lwp *l)
{
        int revents;

        if (minor(dev) != 0) {
                return (ENODEV);
        }

        revents = events & (POLLOUT | POLLWRNORM);

        /* Attempt to save some work. */
        if ((events & (POLLIN | POLLRDNORM)) == 0)
                return (revents);

        mutex_enter(&btn_event_queue_lock);
        if (btn_event_queue_count) {
                revents |= events & (POLLIN | POLLRDNORM);
        } else {
                selrecord(l, &btn_event_queue_selinfo);
        }
        mutex_exit(&btn_event_queue_lock);

        return (revents);
}

static void
filt_btn_rdetach(struct knote *kn)
{

        mutex_enter(&btn_event_queue_lock);
        selremove_knote(&btn_event_queue_selinfo, kn);
        mutex_exit(&btn_event_queue_lock);
}

static int
filt_btn_read(struct knote *kn, long hint)
{
        int rv;

        if (hint & NOTE_SUBMIT) {
                KASSERT(mutex_owned(&btn_event_queue_lock));
        } else {
                mutex_enter(&btn_event_queue_lock);
        }

        kn->kn_data = btn_event_queue_count;
        rv = kn->kn_data > 0;

        if ((hint & NOTE_SUBMIT) == 0) {
                mutex_exit(&btn_event_queue_lock);
        }

        return rv;
}

static const struct filterops btn_read_filtops = {
    .f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
    .f_attach = NULL,
    .f_detach = filt_btn_rdetach,
    .f_event = filt_btn_read,
};

int
btnkqfilter(dev_t dev, struct knote *kn)
{

        if (minor(dev) != 0) {
                return (ENODEV);
        }

        switch (kn->kn_filter) {
        case EVFILT_READ:
                kn->kn_fop = &btn_read_filtops;
                mutex_enter(&btn_event_queue_lock);
                selrecord_knote(&btn_event_queue_selinfo, kn);
                mutex_exit(&btn_event_queue_lock);
                break;

        case EVFILT_WRITE:
                kn->kn_fop = &seltrue_filtops;
                break;

        default:
                return (EINVAL);
        }

        return (0);
}

void
btn_settype(const char *type)
{

        /*
         * Don't bother locking this; it's going to be set
         * during autoconfiguration, and then only read from
         * then on.
         */
        strlcpy(btn_type, type, sizeof(btn_type));
}

int
btn_event_register(struct btn_event *bev)
{

        mutex_enter(&btn_event_list_lock);
        LIST_INSERT_HEAD(&btn_event_list, bev, bev_list);
        mutex_exit(&btn_event_list_lock);

        return (0);
}

void
btn_event_unregister(struct btn_event *bev)
{

        mutex_enter(&btn_event_list_lock);
        LIST_REMOVE(bev, bev_list);
        mutex_exit(&btn_event_list_lock);
}

void
btn_event_send(struct btn_event *bev, int event)
{
        button_event_t btnev;
        int rv;

        mutex_enter(&btn_event_queue_lock);
        if (btn_daemon == NULL) {
                mutex_exit(&btn_event_queue_lock);
                printf("%s: btn_event_send can't handle me.\n", bev->bev_name);
                return;
        }

        btnev.bev_type = BUTTON_EVENT_STATE_CHANGE;
        btnev.bev_event.bs_state = event;
        strcpy(btnev.bev_event.bs_name, bev->bev_name);

        rv = btn_queue_event(&btnev);
        if (rv == 0) {
                mutex_exit(&btn_event_queue_lock);
                printf("%s: WARNING: state change event %d lost; "
                    "queue full\n", bev->bev_name, btnev.bev_type);
                return;
        }
        if (btn_event_queue_flags & BEVQ_F_WAITING) {
                btn_event_queue_flags &= ~BEVQ_F_WAITING;
                cv_broadcast(&btn_event_queue_cv);
        }
        selnotify(&btn_event_queue_selinfo, POLLIN | POLLRDNORM, NOTE_SUBMIT);
        mutex_exit(&btn_event_queue_lock);
}