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