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/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
*
* Original APM BIOS checking by Stephen Rothwell, May 1994
* (sfr@canb.auug.org.au)
*
* This file is part of the Linux kernel, and is made available under
* the terms of the GNU General Public License version 2.
*
* ----------------------------------------------------------------------- */
/*
* arch/i386/boot/apm.c
*
* Get APM BIOS information
*/
#include "boot.h"
int query_apm_bios(void)
{
u16 ax, bx, cx, dx, di;
u32 ebx, esi;
u8 err;
/* APM BIOS installation check */
ax = 0x5300;
bx = cx = 0;
asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %0"
: "=d" (err), "+a" (ax), "+b" (bx), "+c" (cx)
: : "esi", "edi");
if (err)
return -1; /* No APM BIOS */
if (bx != 0x504d) /* "PM" signature */
return -1;
if (!(cx & 0x02)) /* 32 bits supported? */
return -1;
/* Disconnect first, just in case */
ax = 0x5304;
bx = 0;
asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp"
: "+a" (ax), "+b" (bx)
: : "ecx", "edx", "esi", "edi");
/* Paranoia */
ebx = esi = 0;
cx = dx = di = 0;
/* 32-bit connect */
asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %6"
: "=a" (ax), "+b" (ebx), "+c" (cx), "+d" (dx),
"+S" (esi), "+D" (di), "=m" (err)
: "a" (0x5303));
boot_params.apm_bios_info.cseg = ax;
boot_params.apm_bios_info.offset = ebx;
boot_params.apm_bios_info.cseg_16 = cx;
boot_params.apm_bios_info.dseg = dx;
boot_params.apm_bios_info.cseg_len = (u16)esi;
boot_params.apm_bios_info.cseg_16_len = esi >> 16;
boot_params.apm_bios_info.dseg_len = di;
if (err)
return -1;
/* Redo the installation check as the 32-bit connect;
some BIOSes return different flags this way... */
ax = 0x5300;
bx = cx = 0;
asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %0"
: "=d" (err), "+a" (ax), "+b" (bx), "+c" (cx)
: : "esi", "edi");
if (err || bx != 0x504d) {
/* Failure with 32-bit connect, try to disconect and ignore */
ax = 0x5304;
bx = 0;
asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp"
: "+a" (ax), "+b" (bx)
: : "ecx", "edx", "esi", "edi");
return -1;
}
boot_params.apm_bios_info.version = ax;
boot_params.apm_bios_info.flags = cx;
return 0;
}
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