xref: /src/sys/dev/cninit.c

/*	$NetBSD: cninit.c,v 1.13 2020/07/17 02:16:57 uwe Exp $	*/

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * 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. Neither the name of the University 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.
 *
 * from: Utah $Hdr: cons.c 1.7 92/01/21$
 *
 *	@(#)cons.c	8.2 (Berkeley) 1/12/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: cninit.c,v 1.13 2020/07/17 02:16:57 uwe Exp $");

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/systm.h>
#include <sys/buf.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/file.h>
#include <sys/conf.h>
#include <sys/vnode.h>

#include <dev/cons.h>

void
cninit(void)
{
	struct consdev *bestMatch;
	struct consdev *cp;

	cn_tab = NULL;

	/*
	 * Collect information about all possible consoles
	 * and find the one with highest priority
	 */
	bestMatch = NULL;
	for (cp = constab; cp->cn_probe; cp++) {
		(*cp->cn_probe)(cp);
		if (cp->cn_pri > CN_DEAD &&
		    (bestMatch == NULL || cp->cn_pri > bestMatch->cn_pri)) {
			bestMatch = cp;
		}
	}

	/*
	 * No console, we can handle it
	 */
	if (bestMatch == NULL)
		return;

	/*
	 * Turn on console
	 */
	{
		/* XXX: can this ever be non-NULL? */
		struct consdev *old_cn_tab = cn_tab;

		/* cn_init may set cn_tab to self */
 		(*bestMatch->cn_init)(bestMatch);

		/*
		 * Now let everyone know we have an active console they can
		 * use for diagnostics. If we use cn_tab in the search loop
		 * then interrupts from the ethernet at boot may cause system
		 * hang.
		 */
		if (cn_tab == old_cn_tab) /* if cn_init didn't, set it */
			cn_tab = bestMatch;
	}
}