1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /* -*- linux-c -*- ------------------------------------------------------- *
3*4882a593Smuzhiyun *
4*4882a593Smuzhiyun * Copyright (C) 1991, 1992 Linus Torvalds
5*4882a593Smuzhiyun * Copyright 2007 rPath, Inc. - All Rights Reserved
6*4882a593Smuzhiyun * Copyright 2009 Intel Corporation; author H. Peter Anvin
7*4882a593Smuzhiyun *
8*4882a593Smuzhiyun * Original APM BIOS checking by Stephen Rothwell, May 1994
9*4882a593Smuzhiyun * (sfr@canb.auug.org.au)
10*4882a593Smuzhiyun *
11*4882a593Smuzhiyun * ----------------------------------------------------------------------- */
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun /*
14*4882a593Smuzhiyun * Get APM BIOS information
15*4882a593Smuzhiyun */
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #include "boot.h"
18*4882a593Smuzhiyun
query_apm_bios(void)19*4882a593Smuzhiyun int query_apm_bios(void)
20*4882a593Smuzhiyun {
21*4882a593Smuzhiyun struct biosregs ireg, oreg;
22*4882a593Smuzhiyun
23*4882a593Smuzhiyun /* APM BIOS installation check */
24*4882a593Smuzhiyun initregs(&ireg);
25*4882a593Smuzhiyun ireg.ah = 0x53;
26*4882a593Smuzhiyun intcall(0x15, &ireg, &oreg);
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun if (oreg.flags & X86_EFLAGS_CF)
29*4882a593Smuzhiyun return -1; /* No APM BIOS */
30*4882a593Smuzhiyun
31*4882a593Smuzhiyun if (oreg.bx != 0x504d) /* "PM" signature */
32*4882a593Smuzhiyun return -1;
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun if (!(oreg.cx & 0x02)) /* 32 bits supported? */
35*4882a593Smuzhiyun return -1;
36*4882a593Smuzhiyun
37*4882a593Smuzhiyun /* Disconnect first, just in case */
38*4882a593Smuzhiyun ireg.al = 0x04;
39*4882a593Smuzhiyun intcall(0x15, &ireg, NULL);
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun /* 32-bit connect */
42*4882a593Smuzhiyun ireg.al = 0x03;
43*4882a593Smuzhiyun intcall(0x15, &ireg, &oreg);
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun boot_params.apm_bios_info.cseg = oreg.ax;
46*4882a593Smuzhiyun boot_params.apm_bios_info.offset = oreg.ebx;
47*4882a593Smuzhiyun boot_params.apm_bios_info.cseg_16 = oreg.cx;
48*4882a593Smuzhiyun boot_params.apm_bios_info.dseg = oreg.dx;
49*4882a593Smuzhiyun boot_params.apm_bios_info.cseg_len = oreg.si;
50*4882a593Smuzhiyun boot_params.apm_bios_info.cseg_16_len = oreg.hsi;
51*4882a593Smuzhiyun boot_params.apm_bios_info.dseg_len = oreg.di;
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun if (oreg.flags & X86_EFLAGS_CF)
54*4882a593Smuzhiyun return -1;
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun /* Redo the installation check as the 32-bit connect;
57*4882a593Smuzhiyun some BIOSes return different flags this way... */
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun ireg.al = 0x00;
60*4882a593Smuzhiyun intcall(0x15, &ireg, &oreg);
61*4882a593Smuzhiyun
62*4882a593Smuzhiyun if ((oreg.eflags & X86_EFLAGS_CF) || oreg.bx != 0x504d) {
63*4882a593Smuzhiyun /* Failure with 32-bit connect, try to disconnect and ignore */
64*4882a593Smuzhiyun ireg.al = 0x04;
65*4882a593Smuzhiyun intcall(0x15, &ireg, NULL);
66*4882a593Smuzhiyun return -1;
67*4882a593Smuzhiyun }
68*4882a593Smuzhiyun
69*4882a593Smuzhiyun boot_params.apm_bios_info.version = oreg.ax;
70*4882a593Smuzhiyun boot_params.apm_bios_info.flags = oreg.cx;
71*4882a593Smuzhiyun return 0;
72*4882a593Smuzhiyun }
73*4882a593Smuzhiyun
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