biosdisk_ll.c revision 1.18
1 /* $NetBSD: biosdisk_ll.c,v 1.18 2003/06/25 04:21:51 thorpej 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(int); 49 extern void int13_getextinfo(int, struct biosdisk_ext13info *); 50 extern int int13_extension(int); 51 extern int biosread(int, int, int, int, int, void *); 52 extern int biosdiskreset(int); 53 extern int biosextread(int, void *); 54 static int do_read(struct biosdisk_ll *, daddr_t, int, char *); 55 extern u_int vtophys(void *); 56 57 /* 58 * we get from get_diskinfo(): 59 * xxxx %ch %cl %dh (registers after int13/8), ie 60 * xxxx cccc Csss hhhh 61 */ 62 #define SPT(di) (((di)>>8)&0x3f) 63 #define HEADS(di) (((di)&0xff)+1) 64 #define CYL(di) (((((di)>>16)&0xff)|(((di)>>6)&0x300))+1) 65 66 #ifndef BIOSDISK_RETRIES 67 #define BIOSDISK_RETRIES 5 68 #endif 69 70 int 71 set_geometry(struct biosdisk_ll *d, struct biosdisk_ext13info *ed) 72 { 73 int diskinfo; 74 char buf[512]; 75 76 diskinfo = get_diskinfo(d->dev); 77 d->sec = SPT(diskinfo); 78 d->head = HEADS(diskinfo); 79 d->cyl = CYL(diskinfo); 80 d->chs_sectors = d->sec * d->head * d->cyl; 81 82 d->flags = 0; 83 if ((d->dev & 0x80) && int13_extension(d->dev)) { 84 d->flags |= BIOSDISK_EXT13; 85 if (ed != NULL) { 86 ed->size = sizeof *ed; 87 int13_getextinfo(d->dev, ed); 88 } 89 } 90 91 /* 92 * If the drive is 2.88 floppy drive, check that we can actually 93 * read sector >= 18. If not, assume 1.44 floppy disk. 94 */ 95 if (d->dev == 0 && SPT(diskinfo) == 36) { 96 if (biosread(d->dev, 0, 0, 18, 1, buf)) { 97 d->sec = 18; 98 d->chs_sectors /= 2; 99 } 100 } 101 102 /* 103 * get_diskinfo assumes floppy if BIOS call fails. Check at least 104 * "valid" geometry. 105 */ 106 return (!d->sec || !d->head); 107 } 108 109 /* 110 * Global shared "diskbuf" is used as read ahead buffer. For reading from 111 * floppies, the bootstrap has to be loaded on a 64K boundary to ensure that 112 * this buffer doesn't cross a 64K DMA boundary. 113 */ 114 #define RA_SECTORS (DISKBUFSIZE / BIOSDISK_SECSIZE) 115 static int ra_dev; 116 static int ra_end; 117 static int ra_first; 118 119 /* 120 * Because some older BIOSes have bugs in their int13 extensions, we 121 * only try to use the extended read if the I/O request can't be addressed 122 * using CHS. 123 * 124 * Of course, some BIOSes have bugs in ths CHS read, such as failing to 125 * function properly if the MBR table has a different geometry than the 126 * BIOS would generate internally for the device in question, and so we 127 * provide a way to force the extended on hard disks via a compile-time 128 * option. 129 */ 130 #if defined(FORCE_INT13EXT) 131 #define NEED_INT13EXT(d, dblk, num) \ 132 (((d)->dev & 0x80) != 0) 133 #else 134 #define NEED_INT13EXT(d, dblk, num) \ 135 (((d)->dev & 0x80) != 0 && ((dblk) + (num)) >= (d)->chs_sectors) 136 #endif 137 138 static int 139 do_read(struct biosdisk_ll *d, daddr_t dblk, int num, char *buf) 140 { 141 int cyl, head, sec, nsec, spc, dblk32; 142 struct { 143 int8_t size; 144 int8_t resvd; 145 int16_t cnt; 146 int16_t off; 147 int16_t seg; 148 int64_t sec; 149 } ext; 150 151 if (NEED_INT13EXT(d, dblk, num)) { 152 if (!(d->flags & BIOSDISK_EXT13)) 153 return -1; 154 ext.size = sizeof(ext); 155 ext.resvd = 0; 156 ext.cnt = num; 157 /* seg:off of physical address */ 158 ext.off = (int)buf & 0xf; 159 ext.seg = vtophys(buf) >> 4; 160 ext.sec = dblk; 161 162 if (biosextread(d->dev, &ext)) { 163 (void)biosdiskreset(d->dev); 164 return -1; 165 } 166 167 return ext.cnt; 168 } else { 169 dblk32 = (int)dblk; 170 spc = d->head * d->sec; 171 cyl = dblk32 / spc; 172 head = (dblk32 % spc) / d->sec; 173 sec = dblk32 % d->sec; 174 nsec = d->sec - sec; 175 176 if (nsec > num) 177 nsec = num; 178 179 if (biosread(d->dev, cyl, head, sec, nsec, buf)) { 180 (void)biosdiskreset(d->dev); 181 return -1; 182 } 183 184 return nsec; 185 } 186 } 187 188 /* NB if 'cold' is set below not all of the program is loaded, so 189 * musn't use data segment, bss, call library functions or do 190 * read-ahead. 191 */ 192 193 int 194 readsects(struct biosdisk_ll *d, daddr_t dblk, int num, char *buf, int cold) 195 { 196 #ifdef BOOTXX 197 #define cold 1 /* collapse out references to diskbufp */ 198 #endif 199 while (num) { 200 int nsec; 201 202 /* check for usable data in read-ahead buffer */ 203 if (cold || diskbuf_user != &ra_dev || d->dev != ra_dev 204 || dblk < ra_first || dblk >= ra_end) { 205 206 /* no, read from disk */ 207 char *trbuf; 208 int maxsecs; 209 int retries = BIOSDISK_RETRIES; 210 211 if (cold) { 212 /* transfer directly to buffer */ 213 trbuf = buf; 214 maxsecs = num; 215 } else { 216 /* fill read-ahead buffer */ 217 trbuf = alloc_diskbuf(0); /* no data yet */ 218 maxsecs = RA_SECTORS; 219 } 220 221 while ((nsec = do_read(d, dblk, maxsecs, trbuf)) < 0) { 222 #ifdef DISK_DEBUG 223 if (!cold) 224 printf("read error dblk %d-%d\n", dblk, 225 dblk + maxsecs - 1); 226 #endif 227 if (--retries >= 0) 228 continue; 229 return (-1); /* XXX cannot output here if 230 * (cold) */ 231 } 232 if (!cold) { 233 ra_dev = d->dev; 234 ra_first = dblk; 235 ra_end = dblk + nsec; 236 diskbuf_user = &ra_dev; 237 } 238 } else /* can take blocks from end of read-ahead 239 * buffer */ 240 nsec = ra_end - dblk; 241 242 if (!cold) { 243 /* copy data from read-ahead to user buffer */ 244 if (nsec > num) 245 nsec = num; 246 memcpy(buf, 247 diskbufp + (dblk - ra_first) * BIOSDISK_SECSIZE, 248 nsec * BIOSDISK_SECSIZE); 249 } 250 buf += nsec * BIOSDISK_SECSIZE; 251 num -= nsec; 252 dblk += nsec; 253 } 254 255 return (0); 256 } 257
Indexes created Tue Sep 30 11:09:46 GMT 2025