1 /* -*- linux-c -*- ------------------------------------------------------- * 2 * 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright 2007 rPath, Inc. - All Rights Reserved 5 * 6 * This file is part of the Linux kernel, and is made available under 7 * the terms of the GNU General Public License version 2. 8 * 9 * ----------------------------------------------------------------------- */ 10 11 /* 12 * arch/i386/boot/video-bios.c 13 * 14 * Standard video BIOS modes 15 * 16 * We have two options for this; silent and scanned. 17 */ 18 19 #include "boot.h" 20 #include "video.h" 21 22 __videocard video_bios; 23 24 /* Set a conventional BIOS mode */ 25 static int set_bios_mode(u8 mode); 26 27 static int bios_set_mode(struct mode_info *mi) 28 { 29 return set_bios_mode(mi->mode - VIDEO_FIRST_BIOS); 30 } 31 32 static int set_bios_mode(u8 mode) 33 { 34 u16 ax; 35 u8 new_mode; 36 37 ax = mode; /* AH=0x00 Set Video Mode */ 38 asm volatile(INT10 39 : "+a" (ax) 40 : : "ebx", "ecx", "edx", "esi", "edi"); 41 42 ax = 0x0f00; /* Get Current Video Mode */ 43 asm volatile(INT10 44 : "+a" (ax) 45 : : "ebx", "ecx", "edx", "esi", "edi"); 46 47 do_restore = 1; /* Assume video contents were lost */ 48 new_mode = ax & 0x7f; /* Not all BIOSes are clean with the top bit */ 49 50 if (new_mode == mode) 51 return 0; /* Mode change OK */ 52 53 if (new_mode != boot_params.screen_info.orig_video_mode) { 54 /* Mode setting failed, but we didn't end up where we 55 started. That's bad. Try to revert to the original 56 video mode. */ 57 ax = boot_params.screen_info.orig_video_mode; 58 asm volatile(INT10 59 : "+a" (ax) 60 : : "ebx", "ecx", "edx", "esi", "edi"); 61 } 62 return -1; 63 } 64 65 static int bios_probe(void) 66 { 67 u8 mode; 68 u8 saved_mode = boot_params.screen_info.orig_video_mode; 69 u16 crtc; 70 struct mode_info *mi; 71 int nmodes = 0; 72 73 if (adapter != ADAPTER_EGA && adapter != ADAPTER_VGA) 74 return 0; 75 76 set_fs(0); 77 crtc = vga_crtc(); 78 79 video_bios.modes = GET_HEAP(struct mode_info, 0); 80 81 for (mode = 0x14; mode <= 0x7f; mode++) { 82 if (!heap_free(sizeof(struct mode_info))) 83 break; 84 85 if (mode_defined(VIDEO_FIRST_BIOS+mode)) 86 continue; 87 88 if (set_bios_mode(mode)) 89 continue; 90 91 /* Try to verify that it's a text mode. */ 92 93 /* Attribute Controller: make graphics controller disabled */ 94 if (in_idx(0x3c0, 0x10) & 0x01) 95 continue; 96 97 /* Graphics Controller: verify Alpha addressing enabled */ 98 if (in_idx(0x3ce, 0x06) & 0x01) 99 continue; 100 101 /* CRTC cursor location low should be zero(?) */ 102 if (in_idx(crtc, 0x0f)) 103 continue; 104 105 mi = GET_HEAP(struct mode_info, 1); 106 mi->mode = VIDEO_FIRST_BIOS+mode; 107 mi->depth = 0; /* text */ 108 mi->x = rdfs16(0x44a); 109 mi->y = rdfs8(0x484)+1; 110 nmodes++; 111 } 112 113 set_bios_mode(saved_mode); 114 115 return nmodes; 116 } 117 118 __videocard video_bios = 119 { 120 .card_name = "BIOS", 121 .probe = bios_probe, 122 .set_mode = bios_set_mode, 123 .unsafe = 1, 124 .xmode_first = VIDEO_FIRST_BIOS, 125 .xmode_n = 0x80, 126 }; 127