blob: d3e978030c5c6d3a0bbaadca609869f4b895d141 [file] [log] [blame]
H. Peter Anvind13444a2007-07-11 12:18:48 -07001/* -*- linux-c -*- ------------------------------------------------------- *
2 *
3 * Copyright (C) 1991, 1992 Linus Torvalds
4 * Copyright 2007 rPath, Inc. - All Rights Reserved
5 *
6 * This file is part of the Linux kernel, and is made available under
7 * the terms of the GNU General Public License version 2.
8 *
9 * ----------------------------------------------------------------------- */
10
11/*
12 * arch/i386/boot/edd.c
13 *
14 * Get EDD BIOS disk information
15 */
16
17#include "boot.h"
18#include <linux/edd.h>
19
20#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
21
H. Peter Anvind13444a2007-07-11 12:18:48 -070022/*
23 * Read the MBR (first sector) from a specific device.
24 */
25static int read_mbr(u8 devno, void *buf)
26{
H. Peter Anvinc1a6e2b2007-08-13 16:27:42 -070027 u16 ax, bx, cx, dx;
H. Peter Anvind13444a2007-07-11 12:18:48 -070028
29 ax = 0x0201; /* Legacy Read, one sector */
30 cx = 0x0001; /* Sector 0-0-1 */
31 dx = devno;
32 bx = (size_t)buf;
H. Peter Anvinb0151242007-08-22 16:28:01 -070033 asm volatile("pushfl; stc; int $0x13; setc %%al; popfl"
34 : "+a" (ax), "+c" (cx), "+d" (dx), "+b" (bx)
35 : : "esi", "edi", "memory");
H. Peter Anvind13444a2007-07-11 12:18:48 -070036
37 return -(u8)ax; /* 0 or -1 */
38}
39
H. Peter Anvin9a5f35d2007-08-14 17:36:00 -070040static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
H. Peter Anvind13444a2007-07-11 12:18:48 -070041{
42 int sector_size;
43 char *mbrbuf_ptr, *mbrbuf_end;
H. Peter Anvind13444a2007-07-11 12:18:48 -070044 u32 buf_base, mbr_base;
45 extern char _end[];
H. Peter Anvind13444a2007-07-11 12:18:48 -070046
47 sector_size = ei->params.bytes_per_sector;
48 if (!sector_size)
49 sector_size = 512; /* Best available guess */
50
H. Peter Anvinff659d12007-07-31 16:17:13 -040051 /* Produce a naturally aligned buffer on the heap */
H. Peter Anvind13444a2007-07-11 12:18:48 -070052 buf_base = (ds() << 4) + (u32)&_end;
53 mbr_base = (buf_base+sector_size-1) & ~(sector_size-1);
H. Peter Anvinff659d12007-07-31 16:17:13 -040054 mbrbuf_ptr = _end + (mbr_base-buf_base);
H. Peter Anvind13444a2007-07-11 12:18:48 -070055 mbrbuf_end = mbrbuf_ptr + sector_size;
56
H. Peter Anvinff659d12007-07-31 16:17:13 -040057 /* Make sure we actually have space on the heap... */
H. Peter Anvind13444a2007-07-11 12:18:48 -070058 if (!(boot_params.hdr.loadflags & CAN_USE_HEAP))
H. Peter Anvin9a5f35d2007-08-14 17:36:00 -070059 return -1;
H. Peter Anvind13444a2007-07-11 12:18:48 -070060 if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr)
H. Peter Anvin9a5f35d2007-08-14 17:36:00 -070061 return -1;
H. Peter Anvind13444a2007-07-11 12:18:48 -070062
63 if (read_mbr(devno, mbrbuf_ptr))
H. Peter Anvin9a5f35d2007-08-14 17:36:00 -070064 return -1;
H. Peter Anvind13444a2007-07-11 12:18:48 -070065
H. Peter Anvin9a5f35d2007-08-14 17:36:00 -070066 *mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET];
67 return 0;
H. Peter Anvind13444a2007-07-11 12:18:48 -070068}
69
70static int get_edd_info(u8 devno, struct edd_info *ei)
71{
72 u16 ax, bx, cx, dx, di;
73
74 memset(ei, 0, sizeof *ei);
75
76 /* Check Extensions Present */
77
78 ax = 0x4100;
79 bx = EDDMAGIC1;
80 dx = devno;
81 asm("pushfl; stc; int $0x13; setc %%al; popfl"
82 : "+a" (ax), "+b" (bx), "=c" (cx), "+d" (dx)
83 : : "esi", "edi");
84
85 if ((u8)ax)
86 return -1; /* No extended information */
87
88 if (bx != EDDMAGIC2)
89 return -1;
90
91 ei->device = devno;
92 ei->version = ax >> 8; /* EDD version number */
93 ei->interface_support = cx; /* EDD functionality subsets */
94
95 /* Extended Get Device Parameters */
96
97 ei->params.length = sizeof(ei->params);
98 ax = 0x4800;
99 dx = devno;
100 asm("pushfl; int $0x13; popfl"
H. Peter Anvin463c9a92007-08-02 13:45:49 -0400101 : "+a" (ax), "+d" (dx), "=m" (ei->params)
H. Peter Anvind13444a2007-07-11 12:18:48 -0700102 : "S" (&ei->params)
103 : "ebx", "ecx", "edi");
104
105 /* Get legacy CHS parameters */
106
107 /* Ralf Brown recommends setting ES:DI to 0:0 */
108 ax = 0x0800;
109 dx = devno;
110 di = 0;
111 asm("pushw %%es; "
112 "movw %%di,%%es; "
113 "pushfl; stc; int $0x13; setc %%al; popfl; "
114 "popw %%es"
115 : "+a" (ax), "=b" (bx), "=c" (cx), "+d" (dx), "+D" (di)
116 : : "esi");
117
118 if ((u8)ax == 0) {
119 ei->legacy_max_cylinder = (cx >> 8) + ((cx & 0xc0) << 2);
120 ei->legacy_max_head = dx >> 8;
121 ei->legacy_sectors_per_track = cx & 0x3f;
122 }
123
124 return 0;
125}
126
127void query_edd(void)
128{
129 char eddarg[8];
130 int do_mbr = 1;
131 int do_edd = 1;
devzero@web.dee479c832008-01-30 13:33:03 +0100132 int be_quiet;
H. Peter Anvind13444a2007-07-11 12:18:48 -0700133 int devno;
134 struct edd_info ei, *edp;
H. Peter Anvin9a5f35d2007-08-14 17:36:00 -0700135 u32 *mbrptr;
H. Peter Anvind13444a2007-07-11 12:18:48 -0700136
137 if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) {
138 if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip"))
139 do_mbr = 0;
140 else if (!strcmp(eddarg, "off"))
141 do_edd = 0;
142 }
143
devzero@web.dee479c832008-01-30 13:33:03 +0100144 be_quiet = cmdline_find_option_bool("quiet");
145
H. Peter Anvin9a5f35d2007-08-14 17:36:00 -0700146 edp = boot_params.eddbuf;
147 mbrptr = boot_params.edd_mbr_sig_buffer;
H. Peter Anvind13444a2007-07-11 12:18:48 -0700148
149 if (!do_edd)
150 return;
151
devzero@web.dee479c832008-01-30 13:33:03 +0100152 /* Bugs in OnBoard or AddOnCards Bios may hang the EDD probe,
153 * so give a hint if this happens.
154 */
155
156 if (!be_quiet)
H. Peter Anvinf7775012008-01-30 13:33:03 +0100157 printf("Probing EDD... ");
devzero@web.dee479c832008-01-30 13:33:03 +0100158
H. Peter Anvind13444a2007-07-11 12:18:48 -0700159 for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) {
160 /*
161 * Scan the BIOS-supported hard disks and query EDD
162 * information...
163 */
164 get_edd_info(devno, &ei);
165
166 if (boot_params.eddbuf_entries < EDDMAXNR) {
167 memcpy(edp, &ei, sizeof ei);
168 edp++;
169 boot_params.eddbuf_entries++;
170 }
171
H. Peter Anvin9a5f35d2007-08-14 17:36:00 -0700172 if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++))
173 boot_params.edd_mbr_sig_buf_entries = devno-0x80+1;
H. Peter Anvind13444a2007-07-11 12:18:48 -0700174 }
devzero@web.dee479c832008-01-30 13:33:03 +0100175
176 if (!be_quiet)
H. Peter Anvinf7775012008-01-30 13:33:03 +0100177 printf("ok\n");
H. Peter Anvind13444a2007-07-11 12:18:48 -0700178}
179
180#endif