xref: /src/sys/arch/i386/stand/lib/biosdisk_ll.c

/*	$NetBSD: biosdisk_ll.c,v 1.1 1997/03/14 02:40:32 perry Exp $	*/

/*
 * Copyright (c) 1996
 * 	Matthias Drochner.  All rights reserved.
 * Copyright (c) 1996
 * 	Perry E. Metzger.  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 acknowledgements:
 *	This product includes software developed for the NetBSD Project
 *	by Matthias Drochner.
 *	This product includes software developed for the NetBSD Project
 *	by Perry E. Metzger.
 * 4. The names of the authors may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * 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.
 *
 */

/* shared by bootsector startup (bootsectmain)
 and biosdisk.c
 needs lowlevel parts from bios_disk.S
*/

#include <lib/libsa/stand.h>

#include "biosdisk_ll.h"
#include "diskbuf.h"

extern int get_diskinfo __P((int));
extern int biosread __P((int, int, int, int, int, char*));

#define	SPT(di)		((di)&0xff)
#define	HEADS(di)	((((di)>>8)&0xff)+1)

int set_geometry(d)
struct biosdisk_ll *d;
{
  int diskinfo;

  diskinfo = get_diskinfo(d->dev);

  d->spc = (d->spt = SPT(diskinfo)) * HEADS(diskinfo);

  /* get_diskinfo assumes floppy if BIOS call
   fails. Check at least "valid" geometry. */
  return(!d->spc || !d->spt);
}

/* Global shared "diskbuf" is used as read ahead buffer.  For
 * reading from floppies, the bootstrap has to be loaded on a 64K boundary
 * to ensure that this buffer doesn't cross a 64K DMA boundary.
 */
#define RA_SECTORS      (DISKBUFSIZE / BIOSDISK_SECSIZE)
static int ra_dev;
static int ra_end;
static int ra_first;

int readsects(d, dblk, num, buf, cold)	/* reads ahead if (!cold) */
struct biosdisk_ll *d;
int dblk, num;
char *buf;
int cold; /* don't use data segment or bss, don't call library functions */
{
    while(num) {
	int nsec;

	/* check for usable data in read-ahead buffer */
	if (cold || diskbuf_user != &ra_dev || d->dev != ra_dev
	    || dblk < ra_first || dblk >= ra_end) {

	    /* no, read from disk */
	    int cyl, head, sec;
	    char *trbuf;

	    cyl = dblk / d->spc;
	    head = (dblk % d->spc) / d->spt;
	    sec = dblk % d->spt;
	    nsec = d->spt - sec;

	    if(cold) {
		/* transfer directly to buffer */
		trbuf = buf;
		if (nsec > num)
		    nsec = num;
	    } else {
		/* fill read-ahead buffer */
		trbuf = diskbuf;
		if (nsec > RA_SECTORS)
		    nsec = RA_SECTORS;

		ra_dev = d->dev;
		ra_first = dblk;
		ra_end = dblk + nsec;
		diskbuf_user = &ra_dev;
	    }

	    if (biosread(d->dev, cyl, head, sec, nsec, trbuf)) {
		if(!cold) diskbuf_user = 0; /* mark invalid */
		return(-1); /* XXX cannot output here if (cold) */
	    }

	} else /* can take blocks from end of read-ahead buffer */
	    nsec = ra_end - dblk;

	if(!cold) {
	    /* copy data from read-ahead to user buffer */
	    if(nsec > num) nsec = num;
	    bcopy(diskbuf + (dblk - ra_first) * BIOSDISK_SECSIZE, buf,
		  nsec * BIOSDISK_SECSIZE);
	}

	buf += nsec * BIOSDISK_SECSIZE;
	num -= nsec;
	dblk += nsec;
    }

    return(0);
}