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 21 int 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 76