/* -*- 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) * * This file is part of the Linux kernel, and is made available under * the terms of the GNU General Public License version 2. * * ----------------------------------------------------------------------- */ /* * 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; }