Merge tag 'gfs2-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/steve...
[linux-2.6-microblaze.git] / arch / x86 / boot / apm.c
1 /* -*- linux-c -*- ------------------------------------------------------- *
2  *
3  *   Copyright (C) 1991, 1992 Linus Torvalds
4  *   Copyright 2007 rPath, Inc. - All Rights Reserved
5  *   Copyright 2009 Intel Corporation; author H. Peter Anvin
6  *
7  *   Original APM BIOS checking by Stephen Rothwell, May 1994
8  *   (sfr@canb.auug.org.au)
9  *
10  *   This file is part of the Linux kernel, and is made available under
11  *   the terms of the GNU General Public License version 2.
12  *
13  * ----------------------------------------------------------------------- */
14
15 /*
16  * Get APM BIOS information
17  */
18
19 #include "boot.h"
20
21 int query_apm_bios(void)
22 {
23         struct biosregs ireg, oreg;
24
25         /* APM BIOS installation check */
26         initregs(&ireg);
27         ireg.ah = 0x53;
28         intcall(0x15, &ireg, &oreg);
29
30         if (oreg.flags & X86_EFLAGS_CF)
31                 return -1;              /* No APM BIOS */
32
33         if (oreg.bx != 0x504d)          /* "PM" signature */
34                 return -1;
35
36         if (!(oreg.cx & 0x02))          /* 32 bits supported? */
37                 return -1;
38
39         /* Disconnect first, just in case */
40         ireg.al = 0x04;
41         intcall(0x15, &ireg, NULL);
42
43         /* 32-bit connect */
44         ireg.al = 0x03;
45         intcall(0x15, &ireg, &oreg);
46
47         boot_params.apm_bios_info.cseg        = oreg.ax;
48         boot_params.apm_bios_info.offset      = oreg.ebx;
49         boot_params.apm_bios_info.cseg_16     = oreg.cx;
50         boot_params.apm_bios_info.dseg        = oreg.dx;
51         boot_params.apm_bios_info.cseg_len    = oreg.si;
52         boot_params.apm_bios_info.cseg_16_len = oreg.hsi;
53         boot_params.apm_bios_info.dseg_len    = oreg.di;
54
55         if (oreg.flags & X86_EFLAGS_CF)
56                 return -1;
57
58         /* Redo the installation check as the 32-bit connect;
59            some BIOSes return different flags this way... */
60
61         ireg.al = 0x00;
62         intcall(0x15, &ireg, &oreg);
63
64         if ((oreg.eflags & X86_EFLAGS_CF) || oreg.bx != 0x504d) {
65                 /* Failure with 32-bit connect, try to disconect and ignore */
66                 ireg.al = 0x04;
67                 intcall(0x15, &ireg, NULL);
68                 return -1;
69         }
70
71         boot_params.apm_bios_info.version = oreg.ax;
72         boot_params.apm_bios_info.flags   = oreg.cx;
73         return 0;
74 }
75