biosdisk_ll.c revision 1.30
1 /* $NetBSD: biosdisk_ll.c,v 1.30 2011/02/21 00:43:19 dyoung Exp $ */ 2 3 /*- 4 * Copyright (c) 2005 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Bang Jun-Young. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * Copyright (c) 1996 34 * Matthias Drochner. All rights reserved. 35 * Copyright (c) 1996 36 * Perry E. Metzger. All rights reserved. 37 * 38 * Redistribution and use in source and binary forms, with or without 39 * modification, are permitted provided that the following conditions 40 * are met: 41 * 1. Redistributions of source code must retain the above copyright 42 * notice, this list of conditions and the following disclaimer. 43 * 2. Redistributions in binary form must reproduce the above copyright 44 * notice, this list of conditions and the following disclaimer in the 45 * documentation and/or other materials provided with the distribution. 46 * 3. All advertising materials mentioning features or use of this software 47 * must display the following acknowledgements: 48 * This product includes software developed for the NetBSD Project 49 * by Matthias Drochner. 50 * This product includes software developed for the NetBSD Project 51 * by Perry E. Metzger. 52 * 4. The names of the authors may not be used to endorse or promote products 53 * derived from this software without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 56 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 57 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 58 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 59 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 60 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 61 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 62 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 63 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 64 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 65 */ 66 67 /* 68 * shared by bootsector startup (bootsectmain) and biosdisk.c 69 * needs lowlevel parts from bios_disk.S 70 */ 71 72 #include <lib/libkern/libkern.h> 73 #include <lib/libsa/stand.h> 74 75 #include "biosdisk_ll.h" 76 #include "diskbuf.h" 77 #include "libi386.h" 78 79 static int do_read(struct biosdisk_ll *, daddr_t, int, char *); 80 81 /* 82 * we get from get_diskinfo(): 83 * %ah %ch %cl %dh (registers after int13/8), ie 84 * xxxxxxxx cccccccc CCssssss hhhhhhhh 85 */ 86 #define STATUS(di) ((di)>>24) 87 #define SPT(di) (((di)>>8)&0x3f) 88 #define HEADS(di) (((di)&0xff)+1) 89 #define CYL(di) (((((di)>>16)&0xff)|(((di)>>6)&0x300))+1) 90 91 #ifndef BIOSDISK_RETRIES 92 #define BIOSDISK_RETRIES 5 93 #endif 94 95 int 96 set_geometry(struct biosdisk_ll *d, struct biosdisk_extinfo *ed) 97 { 98 int diskinfo; 99 100 diskinfo = biosdisk_getinfo(d->dev); 101 d->sec = SPT(diskinfo); 102 d->head = HEADS(diskinfo); 103 d->cyl = CYL(diskinfo); 104 d->chs_sectors = d->sec * d->head * d->cyl; 105 106 if (d->dev >= 0x80 + get_harddrives()) { 107 d->secsize = 2048; 108 d->type = BIOSDISK_TYPE_CD; 109 } else { 110 d->secsize = 512; 111 if (d->dev & 0x80) 112 d->type = BIOSDISK_TYPE_HD; 113 else 114 d->type = BIOSDISK_TYPE_FD; 115 } 116 117 /* 118 * Some broken BIOSes such as one found on Soltek SL-75DRV2 report 119 * that they don't support int13 extension for CD-ROM drives while 120 * they actually do. As a workaround, if the boot device is a CD we 121 * assume that the extension is available. Note that only very old 122 * BIOSes don't support the extended mode, and they don't work with 123 * ATAPI CD-ROM drives, either. So there's no problem. 124 */ 125 d->flags = 0; 126 if (d->type == BIOSDISK_TYPE_CD || 127 (d->type == BIOSDISK_TYPE_HD && biosdisk_int13ext(d->dev))) { 128 d->flags |= BIOSDISK_INT13EXT; 129 if (ed != NULL) { 130 ed->size = sizeof(*ed); 131 if (biosdisk_getextinfo(d->dev, ed) != 0) 132 d->flags &= ~BIOSDISK_INT13EXT; 133 } 134 } 135 136 /* 137 * If the drive is 2.88MB floppy drive, check that we can actually 138 * read sector >= 18. If not, assume 1.44MB floppy disk. 139 */ 140 if (d->type == BIOSDISK_TYPE_FD && SPT(diskinfo) == 36) { 141 char buf[512]; 142 143 if (biosdisk_read(d->dev, 0, 0, 18, 1, buf)) { 144 d->sec = 18; 145 d->chs_sectors /= 2; 146 } 147 } 148 149 return 0; 150 } 151 152 /* 153 * Global shared "diskbuf" is used as read ahead buffer. For reading from 154 * floppies, the bootstrap has to be loaded on a 64K boundary to ensure that 155 * this buffer doesn't cross a 64K DMA boundary. 156 */ 157 static int ra_dev; 158 static daddr_t ra_end; 159 static daddr_t ra_first; 160 161 /* 162 * Because some older BIOSes have bugs in their int13 extensions, we 163 * only try to use the extended read if the I/O request can't be addressed 164 * using CHS. 165 * 166 * Of course, some BIOSes have bugs in ths CHS read, such as failing to 167 * function properly if the MBR table has a different geometry than the 168 * BIOS would generate internally for the device in question, and so we 169 * provide a way to force the extended on hard disks via a compile-time 170 * option. 171 */ 172 #if defined(FORCE_INT13EXT) 173 #define NEED_INT13EXT(d, dblk, num) \ 174 (((d)->dev & 0x80) != 0) 175 #else 176 #define NEED_INT13EXT(d, dblk, num) \ 177 (((d)->type == BIOSDISK_TYPE_CD) || \ 178 ((d)->type == BIOSDISK_TYPE_HD && \ 179 ((dblk) + (num)) >= (d)->chs_sectors)) 180 #endif 181 182 static int 183 do_read(struct biosdisk_ll *d, daddr_t dblk, int num, char *buf) 184 { 185 186 if (NEED_INT13EXT(d, dblk, num)) { 187 struct { 188 int8_t size; 189 int8_t resvd; 190 int16_t cnt; 191 int16_t off; 192 int16_t seg; 193 int64_t sec; 194 } ext; 195 196 if (!(d->flags & BIOSDISK_INT13EXT)) 197 return -1; 198 ext.size = sizeof(ext); 199 ext.resvd = 0; 200 ext.cnt = num; 201 /* seg:off of physical address */ 202 ext.off = (int)buf & 0xf; 203 ext.seg = vtophys(buf) >> 4; 204 ext.sec = dblk; 205 206 if (biosdisk_extread(d->dev, &ext)) { 207 (void)biosdisk_reset(d->dev); 208 return -1; 209 } 210 211 return ext.cnt; 212 } else { 213 int cyl, head, sec, nsec, spc, dblk32; 214 215 dblk32 = (int)dblk; 216 spc = d->head * d->sec; 217 cyl = dblk32 / spc; 218 head = (dblk32 % spc) / d->sec; 219 sec = dblk32 % d->sec; 220 nsec = d->sec - sec; 221 222 if (nsec > num) 223 nsec = num; 224 225 if (biosdisk_read(d->dev, cyl, head, sec, nsec, buf)) { 226 (void)biosdisk_reset(d->dev); 227 return -1; 228 } 229 230 return nsec; 231 } 232 } 233 234 /* 235 * NB if 'cold' is set below not all of the program is loaded, so 236 * mustn't use data segment, bss, call library functions or do read-ahead. 237 */ 238 int 239 readsects(struct biosdisk_ll *d, daddr_t dblk, int num, char *buf, int cold) 240 { 241 #ifdef BOOTXX 242 #define cold 1 /* collapse out references to diskbufp */ 243 #endif 244 while (num) { 245 int nsec; 246 247 /* check for usable data in read-ahead buffer */ 248 if (cold || diskbuf_user != &ra_dev || d->dev != ra_dev 249 || dblk < ra_first || dblk >= ra_end) { 250 251 /* no, read from disk */ 252 char *trbuf; 253 int maxsecs; 254 int retries = BIOSDISK_RETRIES; 255 256 if (cold) { 257 /* transfer directly to buffer */ 258 trbuf = buf; 259 maxsecs = num; 260 } else { 261 /* fill read-ahead buffer */ 262 trbuf = alloc_diskbuf(0); /* no data yet */ 263 maxsecs = DISKBUFSIZE / d->secsize; 264 } 265 266 while ((nsec = do_read(d, dblk, maxsecs, trbuf)) < 0) { 267 #ifdef DISK_DEBUG 268 if (!cold) 269 printf("read error dblk %"PRId64"-%"PRId64"\n", 270 dblk, (dblk + maxsecs - 1)); 271 #endif 272 if (--retries >= 0) 273 continue; 274 return -1; /* XXX cannot output here if 275 * (cold) */ 276 } 277 if (!cold) { 278 ra_dev = d->dev; 279 ra_first = dblk; 280 ra_end = dblk + nsec; 281 diskbuf_user = &ra_dev; 282 } 283 } else /* can take blocks from end of read-ahead 284 * buffer */ 285 nsec = ra_end - dblk; 286 287 if (!cold) { 288 /* copy data from read-ahead to user buffer */ 289 if (nsec > num) 290 nsec = num; 291 memcpy(buf, 292 diskbufp + (dblk - ra_first) * d->secsize, 293 nsec * d->secsize); 294 } 295 buf += nsec * d->secsize; 296 num -= nsec; 297 dblk += nsec; 298 } 299 300 return 0; 301 } 302 303 /* 304 * Return the number of hard disk drives. 305 */ 306 int 307 get_harddrives(void) 308 { 309 /* 310 * Some BIOSes are buggy so that they return incorrect number 311 * of hard drives with int13/ah=8. We read a byte at 0040:0075 312 * instead, which is known to be always correct. 313 */ 314 int n = 0; 315 316 pvbcopy((void *)0x475, &n, 1); 317 318 return n; 319 } 320
Indexes created Tue Sep 30 11:09:46 GMT 2025