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 * Standard video BIOS modes 13 * 14 * We have two options for this; silent and scanned. 15 */ 16 17 #include "boot.h" 18 #include "video.h" 19 20 __videocard video_bios; 21 22 /* Set a conventional BIOS mode */ 23 static int set_bios_mode(u8 mode); 24 25 static int bios_set_mode(struct mode_info *mi) 26 { 27 return set_bios_mode(mi->mode - VIDEO_FIRST_BIOS); 28 } 29 30 static int set_bios_mode(u8 mode) 31 { 32 u16 ax; 33 u8 new_mode; 34 35 ax = mode; /* AH=0x00 Set Video Mode */ 36 asm volatile(INT10 37 : "+a" (ax) 38 : : "ebx", "ecx", "edx", "esi", "edi"); 39 40 ax = 0x0f00; /* Get Current Video Mode */ 41 asm volatile(INT10 42 : "+a" (ax) 43 : : "ebx", "ecx", "edx", "esi", "edi"); 44 45 do_restore = 1; /* Assume video contents were lost */ 46 new_mode = ax & 0x7f; /* Not all BIOSes are clean with the top bit */ 47 48 if (new_mode == mode) 49 return 0; /* Mode change OK */ 50 51 #ifndef _WAKEUP 52 if (new_mode != boot_params.screen_info.orig_video_mode) { 53 /* Mode setting failed, but we didn't end up where we 54 started. That's bad. Try to revert to the original 55 video mode. */ 56 ax = boot_params.screen_info.orig_video_mode; 57 asm volatile(INT10 58 : "+a" (ax) 59 : : "ebx", "ecx", "edx", "esi", "edi"); 60 } 61 #endif 62 return -1; 63 } 64 65 static int bios_probe(void) 66 { 67 u8 mode; 68 #ifdef _WAKEUP 69 u8 saved_mode = 0x03; 70 #else 71 u8 saved_mode = boot_params.screen_info.orig_video_mode; 72 #endif 73 u16 crtc; 74 struct mode_info *mi; 75 int nmodes = 0; 76 77 if (adapter != ADAPTER_EGA && adapter != ADAPTER_VGA) 78 return 0; 79 80 set_fs(0); 81 crtc = vga_crtc(); 82 83 video_bios.modes = GET_HEAP(struct mode_info, 0); 84 85 for (mode = 0x14; mode <= 0x7f; mode++) { 86 if (!heap_free(sizeof(struct mode_info))) 87 break; 88 89 if (mode_defined(VIDEO_FIRST_BIOS+mode)) 90 continue; 91 92 if (set_bios_mode(mode)) 93 continue; 94 95 /* Try to verify that it's a text mode. */ 96 97 /* Attribute Controller: make graphics controller disabled */ 98 if (in_idx(0x3c0, 0x10) & 0x01) 99 continue; 100 101 /* Graphics Controller: verify Alpha addressing enabled */ 102 if (in_idx(0x3ce, 0x06) & 0x01) 103 continue; 104 105 /* CRTC cursor location low should be zero(?) */ 106 if (in_idx(crtc, 0x0f)) 107 continue; 108 109 mi = GET_HEAP(struct mode_info, 1); 110 mi->mode = VIDEO_FIRST_BIOS+mode; 111 mi->depth = 0; /* text */ 112 mi->x = rdfs16(0x44a); 113 mi->y = rdfs8(0x484)+1; 114 nmodes++; 115 } 116 117 set_bios_mode(saved_mode); 118 119 return nmodes; 120 } 121 122 __videocard video_bios = 123 { 124 .card_name = "BIOS", 125 .probe = bios_probe, 126 .set_mode = bios_set_mode, 127 .unsafe = 1, 128 .xmode_first = VIDEO_FIRST_BIOS, 129 .xmode_n = 0x80, 130 }; 131