/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 1997 Michael Smith
 * Copyright (c) 1998 Jonathan Lemon
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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>
__FBSDID("$FreeBSD: releng/12.0/sys/amd64/amd64/bios.c 326257 2017-11-27 15:03:07Z pfg $");

/*
 * Subset of the i386 bios support code.  We cannot make bios16 nor bios32
 * calls, so we can leave that out.  However, searching for bios rom
 * signatures can be useful for locating tables, eg: powernow settings.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <machine/vmparam.h>
#include <machine/pc/bios.h>

#define BIOS_START	0xe0000
#define BIOS_SIZE	0x20000

/*
 * bios_sigsearch
 *
 * Search some or all of the BIOS region for a signature string.
 *
 * (start)	Optional offset returned from this function 
 *		(for searching for multiple matches), or NULL
 *		to start the search from the base of the BIOS.
 *		Note that this will be a _physical_ address in
 *		the range 0xe0000 - 0xfffff.
 * (sig)	is a pointer to the byte(s) of the signature.
 * (siglen)	number of bytes in the signature.
 * (paralen)	signature paragraph (alignment) size.
 * (sigofs)	offset of the signature within the paragraph.
 *
 * Returns the _physical_ address of the found signature, 0 if the
 * signature was not found.
 */

u_int32_t
bios_sigsearch(u_int32_t start, u_char *sig, int siglen, int paralen, int sigofs)
{
    u_char	*sp, *end;
    
    /* compute the starting address */
    if ((start >= BIOS_START) && (start <= (BIOS_START + BIOS_SIZE))) {
	sp = (char *)BIOS_PADDRTOVADDR(start);
    } else if (start == 0) {
	sp = (char *)BIOS_PADDRTOVADDR(BIOS_START);
    } else {
	return 0;				/* bogus start address */
    }

    /* compute the end address */
    end = (u_char *)BIOS_PADDRTOVADDR(BIOS_START + BIOS_SIZE);

    /* loop searching */
    while ((sp + sigofs + siglen) < end) {
	
	/* compare here */
	if (!bcmp(sp + sigofs, sig, siglen)) {
	    /* convert back to physical address */
	    return((u_int32_t)(uintptr_t)BIOS_VADDRTOPADDR(sp));
	}
	sp += paralen;
    }
    return(0);
}
