1 /* ----------------------------------------------------------------------- *
2 *
3 * Copyright 2009 Intel Corporation; author: H. Peter Anvin
4 *
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., 51 Franklin St, Fifth Floor,
8 * Boston MA 02110-1301, USA; either version 2 of the License, or
9 * (at your option) any later version; incorporated herein by reference.
10 *
11 * Based on code from the Linux kernel:
12 *
13 * Copyright (C) 1991, 1992 Linus Torvalds
14 * Copyright 2007 rPath, Inc. - All Rights Reserved
15 *
16 * Original APM BIOS checking by Stephen Rothwell, May 1994
17 * (sfr@canb.auug.org.au)
18 *
19 * This file is part of the Linux kernel, and is made available under
20 * the terms of the GNU General Public License version 2.
21 *
22 * ----------------------------------------------------------------------- */
23
24 /*
25 * apm.c
26 *
27 * APM information for Multiboot
28 */
29
30 #include "mboot.h"
31 #include <com32.h>
32
mboot_apm(void)33 void mboot_apm(void)
34 {
35 static struct apm_info apm;
36 com32sys_t ireg, oreg;
37
38 memset(&ireg, 0, sizeof ireg);
39
40 ireg.eax.w[0] = 0x5300;
41 __intcall(0x15, &ireg, &oreg);
42
43 if (oreg.eflags.l & EFLAGS_CF)
44 return; /* No APM BIOS */
45
46 if (oreg.ebx.w[0] != 0x504d)
47 return; /* No "PM" signature */
48
49 if (!(oreg.ecx.w[0] & 0x02))
50 return; /* 32 bits not supported */
51
52 /* Disconnect first, just in case */
53 memset(&ireg, 0, sizeof ireg);
54 ireg.eax.b[0] = 0x04;
55 __intcall(0x15, &ireg, &oreg);
56
57 /* 32-bit connect */
58 ireg.eax.b[0] = 0x03;
59 __intcall(0x15, &ireg, &oreg);
60
61 apm.cseg = oreg.eax.w[0];
62 apm.offset = oreg.ebx.l;
63 apm.cseg_16 = oreg.ecx.w[0];
64 apm.dseg_16 = oreg.edx.w[0];
65 apm.cseg_len = oreg.esi.w[0];
66 apm.cseg_16_len = oreg.esi.w[1];
67 apm.dseg_16_len = oreg.edi.w[0];
68
69 /* Redo the installation check as the 32-bit connect;
70 some BIOSes return different flags this way... */
71
72 memset(&ireg, 0, sizeof ireg);
73 ireg.eax.b[0] = 0x00;
74 __intcall(0x15, &ireg, &oreg);
75
76 if ((oreg.eflags.l & EFLAGS_CF) || (oreg.ebx.w[0] != 0x504d)) {
77 /* Failure with 32-bit connect, try to disconect and ignore */
78 ireg.eax.b[0] = 0x04;
79 __intcall(0x15, &ireg, NULL);
80 return;
81 }
82
83 apm.version = oreg.eax.w[0];
84
85 mbinfo.apm_table = map_data(&apm, sizeof apm, 4, false);
86 if (mbinfo.apm_table)
87 mbinfo.flags |= MB_INFO_APM_TABLE;
88 }
89