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

 
 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
21int 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