74 строки
1.8 KiB
C
74 строки
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/* -*- linux-c -*- ------------------------------------------------------- *
|
|
*
|
|
* Copyright (C) 1991, 1992 Linus Torvalds
|
|
* Copyright 2007 rPath, Inc. - All Rights Reserved
|
|
* Copyright 2009 Intel Corporation; author H. Peter Anvin
|
|
*
|
|
* Original APM BIOS checking by Stephen Rothwell, May 1994
|
|
* (sfr@canb.auug.org.au)
|
|
*
|
|
* ----------------------------------------------------------------------- */
|
|
|
|
/*
|
|
* Get APM BIOS information
|
|
*/
|
|
|
|
#include "boot.h"
|
|
|
|
int query_apm_bios(void)
|
|
{
|
|
struct biosregs ireg, oreg;
|
|
|
|
/* APM BIOS installation check */
|
|
initregs(&ireg);
|
|
ireg.ah = 0x53;
|
|
intcall(0x15, &ireg, &oreg);
|
|
|
|
if (oreg.flags & X86_EFLAGS_CF)
|
|
return -1; /* No APM BIOS */
|
|
|
|
if (oreg.bx != 0x504d) /* "PM" signature */
|
|
return -1;
|
|
|
|
if (!(oreg.cx & 0x02)) /* 32 bits supported? */
|
|
return -1;
|
|
|
|
/* Disconnect first, just in case */
|
|
ireg.al = 0x04;
|
|
intcall(0x15, &ireg, NULL);
|
|
|
|
/* 32-bit connect */
|
|
ireg.al = 0x03;
|
|
intcall(0x15, &ireg, &oreg);
|
|
|
|
boot_params.apm_bios_info.cseg = oreg.ax;
|
|
boot_params.apm_bios_info.offset = oreg.ebx;
|
|
boot_params.apm_bios_info.cseg_16 = oreg.cx;
|
|
boot_params.apm_bios_info.dseg = oreg.dx;
|
|
boot_params.apm_bios_info.cseg_len = oreg.si;
|
|
boot_params.apm_bios_info.cseg_16_len = oreg.hsi;
|
|
boot_params.apm_bios_info.dseg_len = oreg.di;
|
|
|
|
if (oreg.flags & X86_EFLAGS_CF)
|
|
return -1;
|
|
|
|
/* Redo the installation check as the 32-bit connect;
|
|
some BIOSes return different flags this way... */
|
|
|
|
ireg.al = 0x00;
|
|
intcall(0x15, &ireg, &oreg);
|
|
|
|
if ((oreg.eflags & X86_EFLAGS_CF) || oreg.bx != 0x504d) {
|
|
/* Failure with 32-bit connect, try to disconect and ignore */
|
|
ireg.al = 0x04;
|
|
intcall(0x15, &ireg, NULL);
|
|
return -1;
|
|
}
|
|
|
|
boot_params.apm_bios_info.version = oreg.ax;
|
|
boot_params.apm_bios_info.flags = oreg.cx;
|
|
return 0;
|
|
}
|
|
|