1 /* -*- linux-c -*- ------------------------------------------------------- * 2 * 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright 2007 rPath, Inc. - All Rights Reserved 5 * 6 * Original APM BIOS checking by Stephen Rothwell, May 1994 7 * (sfr@canb.auug.org.au) 8 * 9 * This file is part of the Linux kernel, and is made available under 10 * the terms of the GNU General Public License version 2. 11 * 12 * ----------------------------------------------------------------------- */ 13 14 /* 15 * arch/i386/boot/apm.c 16 * 17 * Get APM BIOS information 18 */ 19 20 #include "boot.h" 21 22 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE) 23 24 int query_apm_bios(void) 25 { 26 u16 ax, bx, cx, dx, di; 27 u32 ebx, esi; 28 u8 err; 29 30 /* APM BIOS installation check */ 31 ax = 0x5300; 32 bx = cx = 0; 33 asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %0" 34 : "=d" (err), "+a" (ax), "+b" (bx), "+c" (cx) 35 : : "esi", "edi"); 36 37 if (err) 38 return -1; /* No APM BIOS */ 39 40 if (bx != 0x504d) /* "PM" signature */ 41 return -1; 42 43 if (!(cx & 0x02)) /* 32 bits supported? */ 44 return -1; 45 46 /* Disconnect first, just in case */ 47 ax = 0x5304; 48 bx = 0; 49 asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp" 50 : "+a" (ax), "+b" (bx) 51 : : "ecx", "edx", "esi", "edi"); 52 53 /* Paranoia */ 54 ebx = esi = 0; 55 cx = dx = di = 0; 56 57 /* 32-bit connect */ 58 asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %6" 59 : "=a" (ax), "+b" (ebx), "+c" (cx), "+d" (dx), 60 "+S" (esi), "+D" (di), "=m" (err) 61 : "a" (0x5303)); 62 63 boot_params.apm_bios_info.cseg = ax; 64 boot_params.apm_bios_info.offset = ebx; 65 boot_params.apm_bios_info.cseg_16 = cx; 66 boot_params.apm_bios_info.dseg = dx; 67 boot_params.apm_bios_info.cseg_len = (u16)esi; 68 boot_params.apm_bios_info.cseg_16_len = esi >> 16; 69 boot_params.apm_bios_info.dseg_len = di; 70 71 if (err) 72 return -1; 73 74 /* Redo the installation check as the 32-bit connect; 75 some BIOSes return different flags this way... */ 76 77 ax = 0x5300; 78 bx = cx = 0; 79 asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp ; setc %0" 80 : "=d" (err), "+a" (ax), "+b" (bx), "+c" (cx) 81 : : "esi", "edi"); 82 83 if (err || bx != 0x504d) { 84 /* Failure with 32-bit connect, try to disconect and ignore */ 85 ax = 0x5304; 86 bx = 0; 87 asm volatile("pushl %%ebp ; int $0x15 ; popl %%ebp" 88 : "+a" (ax), "+b" (bx) 89 : : "ecx", "edx", "esi", "edi"); 90 return -1; 91 } 92 93 boot_params.apm_bios_info.version = ax; 94 boot_params.apm_bios_info.flags = cx; 95 return 0; 96 } 97 98 #endif 99