1 /* $NetBSD: biosdisk_ll.c,v 1.3 1997/06/13 13:36:06 drochner Exp $ */ 2 3 /* 4 * Copyright (c) 1996 5 * Matthias Drochner. All rights reserved. 6 * Copyright (c) 1996 7 * Perry E. Metzger. All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgements: 19 * This product includes software developed for the NetBSD Project 20 * by Matthias Drochner. 21 * This product includes software developed for the NetBSD Project 22 * by Perry E. Metzger. 23 * 4. The names of the authors may not be used to endorse or promote products 24 * derived from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 /* 39 * shared by bootsector startup (bootsectmain) and biosdisk.c 40 * needs lowlevel parts from bios_disk.S 41 */ 42 43 #include <lib/libsa/stand.h> 44 45 #include "biosdisk_ll.h" 46 #include "diskbuf.h" 47 48 extern int get_diskinfo __P((int)); 49 extern int biosread __P((int, int, int, int, int, char *)); 50 51 #define SPT(di) ((di)&0xff) 52 #define HEADS(di) ((((di)>>8)&0xff)+1) 53 54 int 55 set_geometry(d) 56 struct biosdisk_ll *d; 57 { 58 int diskinfo; 59 60 diskinfo = get_diskinfo(d->dev); 61 62 d->spc = (d->spt = SPT(diskinfo)) * HEADS(diskinfo); 63 64 /* 65 * get_diskinfo assumes floppy if BIOS call fails. Check at least 66 * "valid" geometry. 67 */ 68 return (!d->spc || !d->spt); 69 } 70 71 /* 72 * Global shared "diskbuf" is used as read ahead buffer. For reading from 73 * floppies, the bootstrap has to be loaded on a 64K boundary to ensure that 74 * this buffer doesn't cross a 64K DMA boundary. 75 */ 76 #define RA_SECTORS (DISKBUFSIZE / BIOSDISK_SECSIZE) 77 static int ra_dev; 78 static int ra_end; 79 static int ra_first; 80 81 int 82 readsects(d, dblk, num, buf, cold) /* reads ahead if (!cold) */ 83 struct biosdisk_ll *d; 84 int dblk, num; 85 char *buf; 86 int cold; /* don't use data segment or bss, don't call 87 * library functions */ 88 { 89 while (num) { 90 int nsec; 91 92 /* check for usable data in read-ahead buffer */ 93 if (cold || diskbuf_user != &ra_dev || d->dev != ra_dev 94 || dblk < ra_first || dblk >= ra_end) { 95 96 /* no, read from disk */ 97 int cyl, head, sec; 98 char *trbuf; 99 100 cyl = dblk / d->spc; 101 head = (dblk % d->spc) / d->spt; 102 sec = dblk % d->spt; 103 nsec = d->spt - sec; 104 105 if (cold) { 106 /* transfer directly to buffer */ 107 trbuf = buf; 108 if (nsec > num) 109 nsec = num; 110 } else { 111 /* fill read-ahead buffer */ 112 trbuf = diskbuf; 113 if (nsec > RA_SECTORS) 114 nsec = RA_SECTORS; 115 116 ra_dev = d->dev; 117 ra_first = dblk; 118 ra_end = dblk + nsec; 119 diskbuf_user = &ra_dev; 120 } 121 122 if (biosread(d->dev, cyl, head, sec, nsec, trbuf)) { 123 if (!cold) 124 diskbuf_user = 0; /* mark invalid */ 125 return (-1); /* XXX cannot output here if 126 * (cold) */ 127 } 128 } else /* can take blocks from end of read-ahead 129 * buffer */ 130 nsec = ra_end - dblk; 131 132 if (!cold) { 133 /* copy data from read-ahead to user buffer */ 134 if (nsec > num) 135 nsec = num; 136 bcopy(diskbuf + (dblk - ra_first) * BIOSDISK_SECSIZE, 137 buf, nsec * BIOSDISK_SECSIZE); 138 } 139 buf += nsec * BIOSDISK_SECSIZE; 140 num -= nsec; 141 dblk += nsec; 142 } 143 144 return (0); 145 } 146