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d13444a5 PA |
1 | /* -*- linux-c -*- ------------------------------------------------------- * |
2 | * | |
3 | * Copyright (C) 1991, 1992 Linus Torvalds | |
4 | * Copyright 2007 rPath, Inc. - All Rights Reserved | |
3435d347 | 5 | * Copyright 2009 Intel Corporation; author H. Peter Anvin |
d13444a5 PA |
6 | * |
7 | * This file is part of the Linux kernel, and is made available under | |
8 | * the terms of the GNU General Public License version 2. | |
9 | * | |
10 | * ----------------------------------------------------------------------- */ | |
11 | ||
12 | /* | |
d13444a5 PA |
13 | * Get EDD BIOS disk information |
14 | */ | |
15 | ||
16 | #include "boot.h" | |
17 | #include <linux/edd.h> | |
c041b5ad | 18 | #include "string.h" |
d13444a5 PA |
19 | |
20 | #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE) | |
21 | ||
d13444a5 PA |
22 | /* |
23 | * Read the MBR (first sector) from a specific device. | |
24 | */ | |
25 | static int read_mbr(u8 devno, void *buf) | |
26 | { | |
3435d347 | 27 | struct biosregs ireg, oreg; |
d13444a5 | 28 | |
3435d347 PA |
29 | initregs(&ireg); |
30 | ireg.ax = 0x0201; /* Legacy Read, one sector */ | |
31 | ireg.cx = 0x0001; /* Sector 0-0-1 */ | |
32 | ireg.dl = devno; | |
33 | ireg.bx = (size_t)buf; | |
d13444a5 | 34 | |
3435d347 PA |
35 | intcall(0x13, &ireg, &oreg); |
36 | ||
37 | return -(oreg.eflags & X86_EFLAGS_CF); /* 0 or -1 */ | |
d13444a5 PA |
38 | } |
39 | ||
9a5f35d4 | 40 | static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig) |
d13444a5 PA |
41 | { |
42 | int sector_size; | |
43 | char *mbrbuf_ptr, *mbrbuf_end; | |
d13444a5 PA |
44 | u32 buf_base, mbr_base; |
45 | extern char _end[]; | |
6cdcdb99 | 46 | u16 mbr_magic; |
d13444a5 PA |
47 | |
48 | sector_size = ei->params.bytes_per_sector; | |
49 | if (!sector_size) | |
50 | sector_size = 512; /* Best available guess */ | |
51 | ||
ff659d13 | 52 | /* Produce a naturally aligned buffer on the heap */ |
d13444a5 PA |
53 | buf_base = (ds() << 4) + (u32)&_end; |
54 | mbr_base = (buf_base+sector_size-1) & ~(sector_size-1); | |
ff659d13 | 55 | mbrbuf_ptr = _end + (mbr_base-buf_base); |
d13444a5 PA |
56 | mbrbuf_end = mbrbuf_ptr + sector_size; |
57 | ||
ff659d13 | 58 | /* Make sure we actually have space on the heap... */ |
d13444a5 | 59 | if (!(boot_params.hdr.loadflags & CAN_USE_HEAP)) |
9a5f35d4 | 60 | return -1; |
d13444a5 | 61 | if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr) |
9a5f35d4 | 62 | return -1; |
d13444a5 | 63 | |
6cdcdb99 | 64 | memset(mbrbuf_ptr, 0, sector_size); |
d13444a5 | 65 | if (read_mbr(devno, mbrbuf_ptr)) |
9a5f35d4 | 66 | return -1; |
d13444a5 | 67 | |
9a5f35d4 | 68 | *mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET]; |
6cdcdb99 AB |
69 | mbr_magic = *(u16 *)&mbrbuf_ptr[510]; |
70 | ||
71 | /* check for valid MBR magic */ | |
72 | return mbr_magic == 0xAA55 ? 0 : -1; | |
d13444a5 PA |
73 | } |
74 | ||
75 | static int get_edd_info(u8 devno, struct edd_info *ei) | |
76 | { | |
3435d347 | 77 | struct biosregs ireg, oreg; |
d13444a5 PA |
78 | |
79 | memset(ei, 0, sizeof *ei); | |
80 | ||
81 | /* Check Extensions Present */ | |
82 | ||
3435d347 PA |
83 | initregs(&ireg); |
84 | ireg.ah = 0x41; | |
85 | ireg.bx = EDDMAGIC1; | |
86 | ireg.dl = devno; | |
87 | intcall(0x13, &ireg, &oreg); | |
d13444a5 | 88 | |
3435d347 | 89 | if (oreg.eflags & X86_EFLAGS_CF) |
d13444a5 PA |
90 | return -1; /* No extended information */ |
91 | ||
3435d347 | 92 | if (oreg.bx != EDDMAGIC2) |
d13444a5 PA |
93 | return -1; |
94 | ||
95 | ei->device = devno; | |
3435d347 PA |
96 | ei->version = oreg.ah; /* EDD version number */ |
97 | ei->interface_support = oreg.cx; /* EDD functionality subsets */ | |
d13444a5 PA |
98 | |
99 | /* Extended Get Device Parameters */ | |
100 | ||
101 | ei->params.length = sizeof(ei->params); | |
3435d347 PA |
102 | ireg.ah = 0x48; |
103 | ireg.si = (size_t)&ei->params; | |
104 | intcall(0x13, &ireg, &oreg); | |
d13444a5 PA |
105 | |
106 | /* Get legacy CHS parameters */ | |
107 | ||
108 | /* Ralf Brown recommends setting ES:DI to 0:0 */ | |
3435d347 PA |
109 | ireg.ah = 0x08; |
110 | ireg.es = 0; | |
111 | intcall(0x13, &ireg, &oreg); | |
112 | ||
113 | if (!(oreg.eflags & X86_EFLAGS_CF)) { | |
114 | ei->legacy_max_cylinder = oreg.ch + ((oreg.cl & 0xc0) << 2); | |
115 | ei->legacy_max_head = oreg.dh; | |
116 | ei->legacy_sectors_per_track = oreg.cl & 0x3f; | |
d13444a5 PA |
117 | } |
118 | ||
119 | return 0; | |
120 | } | |
121 | ||
122 | void query_edd(void) | |
123 | { | |
124 | char eddarg[8]; | |
125 | int do_mbr = 1; | |
8c4dd606 TG |
126 | #ifdef CONFIG_EDD_OFF |
127 | int do_edd = 0; | |
128 | #else | |
d13444a5 | 129 | int do_edd = 1; |
8c4dd606 | 130 | #endif |
e479c830 | 131 | int be_quiet; |
d13444a5 PA |
132 | int devno; |
133 | struct edd_info ei, *edp; | |
9a5f35d4 | 134 | u32 *mbrptr; |
d13444a5 PA |
135 | |
136 | if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) { | |
8c4dd606 TG |
137 | if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) { |
138 | do_edd = 1; | |
d13444a5 | 139 | do_mbr = 0; |
8c4dd606 | 140 | } |
d13444a5 PA |
141 | else if (!strcmp(eddarg, "off")) |
142 | do_edd = 0; | |
8c4dd606 TG |
143 | else if (!strcmp(eddarg, "on")) |
144 | do_edd = 1; | |
d13444a5 PA |
145 | } |
146 | ||
e479c830 | 147 | be_quiet = cmdline_find_option_bool("quiet"); |
148 | ||
9a5f35d4 PA |
149 | edp = boot_params.eddbuf; |
150 | mbrptr = boot_params.edd_mbr_sig_buffer; | |
d13444a5 PA |
151 | |
152 | if (!do_edd) | |
153 | return; | |
154 | ||
e479c830 | 155 | /* Bugs in OnBoard or AddOnCards Bios may hang the EDD probe, |
156 | * so give a hint if this happens. | |
157 | */ | |
158 | ||
159 | if (!be_quiet) | |
b7107636 | 160 | printf("Probing EDD (edd=off to disable)... "); |
e479c830 | 161 | |
d13444a5 PA |
162 | for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) { |
163 | /* | |
164 | * Scan the BIOS-supported hard disks and query EDD | |
165 | * information... | |
166 | */ | |
f2ba9392 JB |
167 | if (!get_edd_info(devno, &ei) |
168 | && boot_params.eddbuf_entries < EDDMAXNR) { | |
d13444a5 PA |
169 | memcpy(edp, &ei, sizeof ei); |
170 | edp++; | |
171 | boot_params.eddbuf_entries++; | |
172 | } | |
173 | ||
9a5f35d4 PA |
174 | if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++)) |
175 | boot_params.edd_mbr_sig_buf_entries = devno-0x80+1; | |
d13444a5 | 176 | } |
e479c830 | 177 | |
178 | if (!be_quiet) | |
f7775016 | 179 | printf("ok\n"); |
d13444a5 PA |
180 | } |
181 | ||
182 | #endif |