| H. Peter Anvin | 5e8ddcbe | 2007-07-11 12:18:52 -0700 | [diff] [blame^] | 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 was 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->x = rdfs16(0x44a); |
| 108 | mi->y = rdfs8(0x484)+1; |
| 109 | nmodes++; |
| 110 | } |
| 111 | |
| 112 | set_bios_mode(saved_mode); |
| 113 | |
| 114 | return nmodes; |
| 115 | } |
| 116 | |
| 117 | __videocard video_bios = |
| 118 | { |
| 119 | .card_name = "BIOS (scanned)", |
| 120 | .probe = bios_probe, |
| 121 | .set_mode = bios_set_mode, |
| 122 | .unsafe = 1, |
| 123 | .xmode_first = VIDEO_FIRST_BIOS, |
| 124 | .xmode_n = 0x80, |
| 125 | }; |