1 /* ----------------------------------------------------------------------- *
3 * Copyright 2009 Shao Miller - All Rights Reserved
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, Inc., 53 Temple Place Ste 330,
8 * Boston MA 02111-1307, USA; either version 2 of the License, or
9 * (at your option) any later version; incorporated herein by reference.
11 * ----------------------------------------------------------------------- */
16 * Routines for probing BIOS disk drives
19 /* Change to 1 for debugging */
20 #define DBG_DSKPROBE 0
27 /* Function type for printf() */
28 typedef int (f_printf) (const char *, ...);
30 /* Dummy printf() that does nothing */
31 static f_printf no_printf;
32 static f_printf *dskprobe_printfs[] = { no_printf, printf };
34 #define dskprobe_printf (dskprobe_printfs[DBG_DSKPROBE])
36 static void dskprobe_pause(com32sys_t *);
38 /* Probe routine function type */
39 typedef int (f_probe) (uint8_t, com32sys_t *);
40 static f_probe probe_int13h_08h, probe_int13h_15h, probe_int13h_41h;
42 /* We will probe a BIOS drive number using INT 0x13, AH == func */
43 static void probe_any(uint8_t func, uint8_t drive, com32sys_t * regs)
45 regs->eax.b[1] = func; /* AH == sub-function for probe */
46 regs->edx.b[0] = drive; /* DL == drive number to probe */
47 intcall(0x13, regs, regs);
52 * Determine if the return from probe_int13h_01h indicates a failure; a
53 * return of zero indicates no known failure.
55 static int probe_int13h_01h_fail(int istatus)
63 case 1: status = istatus;
69 * INT 0x13, AH == 0x01: Get status of last command.
71 static int probe_int13h_01h(uint8_t drive)
76 memset((void *)(®s), 0, sizeof regs);
77 probe_any(0x01, drive, ®s);
78 status = (regs.eflags.l & 1) * 256 + regs.eax.b[1];
79 dskprobe_printf(" AH01: CF%d AH%02x\n", regs.eflags.l & 1, regs.eax.b[1]);
84 * INT 0x13, AH == 0x08: Get drive parameters.
86 static int probe_int13h_08h(uint8_t drive, com32sys_t * regs)
90 memset(regs, 0, sizeof *regs);
91 probe_any(0x08, drive, regs);
92 present = !(regs->eflags.l & 1) && !regs->eax.b[1];
93 dskprobe_printf(" AH08: P%d CF%d AH%02x AL%02x BL%02x DL%02x\n", present,
94 regs->eflags.l & 1, regs->eax.b[1], regs->eax.b[0],
95 regs->ebx.b[0], regs->edx.b[0]);
100 * INT 0x13, AH == 0x15: Get disk type.
102 static int probe_int13h_15h(uint8_t drive, com32sys_t * regs)
107 memset(regs, 0, sizeof *regs);
108 probe_any(0x15, drive, regs);
109 present = !(regs->eflags.l & 1) && regs->eax.b[1];
110 status = probe_int13h_01h(drive);
111 probe_int13h_01h_fail(status);
112 dskprobe_printf(" AH15: P%d CF%d AH%02x AL%02x CX%04x DX%04x\n", present,
113 regs->eflags.l & 1, regs->eax.b[1], regs->eax.b[0],
114 regs->ecx.w[0], regs->edx.w[0]);
119 * INT 0x13, AH == 0x41: INT 0x13 extensions installation check.
121 static int probe_int13h_41h(uint8_t drive, com32sys_t * regs)
125 memset(regs, 0, sizeof *regs);
126 regs->ebx.w[0] = 0x55AA; /* BX == 0x55AA */
127 probe_any(0x41, drive, regs);
128 present = !(regs->eflags.l & 1) && (regs->ebx.w[0] == 0xAA55);
129 dskprobe_printf(" AH41: P%d CF%d BX%04x AH%02x DH%02x\n", present,
130 regs->eflags.l & 1, regs->ebx.w[0], regs->eax.b[1],
136 * We will probe the BIOS Data Area and count the drives found there.
137 * This heuristic then assumes that all drives of 'drive's type are
138 * found in a contiguous range, and returns 1 if the probed drive
139 * is less than or equal to the BDA count.
140 * This particular function's code is derived from code in setup.c by
141 * H. Peter Anvin. Please respect that file's copyright for this function
143 int probe_bda_drive(uint8_t drive)
149 bios_drives = rdz_8(BIOS_HD_COUNT); /* HDD count */
151 uint8_t equip = rdz_8(BIOS_EQUIP);
153 bios_drives = (equip >> 6) + 1; /* Floppy count */
157 err = (drive - (drive & 0x80)) >= bios_drives ? 0 : 1;
158 dskprobe_printf("BDA drive %02x? %d, total count: %d\n", drive, err,
164 * We will probe a drive with a few different methods, returning
165 * the count of succesful probes
167 int multi_probe_drive(uint8_t drive)
172 dskprobe_printf("INT 13 DL%02x:\n", drive);
173 /* Only probe the BDA for floppies */
176 c += probe_int13h_08h(drive, ®s);
177 c += probe_int13h_15h(drive, ®s);
178 c += probe_int13h_41h(drive, ®s);
180 c += probe_bda_drive(drive);
181 dskprobe_pause(®s);
186 * We will probe a contiguous range of BIOS drive, starting with drive
187 * number 'start'. We probe with a few different methods, and return
188 * the first drive which doesn't respond to any of the probes.
190 uint8_t probe_drive_range(uint8_t start)
192 uint8_t drive = start;
193 while (multi_probe_drive(drive)) {
195 /* Check for passing the floppy/HDD boundary */
196 if ((drive & 0x7F) == 0)
202 /* Dummy printf() that does nothing */
203 static int no_printf(const char *ignored, ...)
209 /* Pause if we are in debug-mode */
210 static void dskprobe_pause(com32sys_t * regs)
214 dskprobe_printf("Press a key to continue...\n");
215 memset(regs, 0, sizeof *regs);
217 intcall(0x16, regs, NULL);