1 // SPDX-License-Identifier: GPL-2.0-only 2 /* -*- linux-c -*- ------------------------------------------------------- * 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * Copyright 2007 rPath, Inc. - All Rights Reserved 6 * Copyright 2009 Intel Corporation; author H. Peter Anvin 7 * 8 * ----------------------------------------------------------------------- */ 9 10 /* 11 * Standard video BIOS modes 12 * 13 * We have two options for this; silent and scanned. 14 */ 15 16 #include "boot.h" 17 #include "video.h" 18 19 static __videocard video_bios; 20 21 /* Set a conventional BIOS mode */ 22 static int set_bios_mode(u8 mode); 23 24 static int bios_set_mode(struct mode_info *mi) 25 { 26 return set_bios_mode(mi->mode - VIDEO_FIRST_BIOS); 27 } 28 29 static int set_bios_mode(u8 mode) 30 { 31 struct biosregs ireg, oreg; 32 u8 new_mode; 33 34 initregs(&ireg); 35 ireg.al = mode; /* AH=0x00 Set Video Mode */ 36 intcall(0x10, &ireg, NULL); 37 38 ireg.ah = 0x0f; /* Get Current Video Mode */ 39 intcall(0x10, &ireg, &oreg); 40 41 do_restore = 1; /* Assume video contents were lost */ 42 43 /* Not all BIOSes are clean with the top bit */ 44 new_mode = oreg.al & 0x7f; 45 46 if (new_mode == mode) 47 return 0; /* Mode change OK */ 48 49 #ifndef _WAKEUP 50 if (new_mode != boot_params.screen_info.orig_video_mode) { 51 /* Mode setting failed, but we didn't end up where we 52 started. That's bad. Try to revert to the original 53 video mode. */ 54 ireg.ax = boot_params.screen_info.orig_video_mode; 55 intcall(0x10, &ireg, NULL); 56 } 57 #endif 58 return -1; 59 } 60 61 static int bios_probe(void) 62 { 63 u8 mode; 64 #ifdef _WAKEUP 65 u8 saved_mode = 0x03; 66 #else 67 u8 saved_mode = boot_params.screen_info.orig_video_mode; 68 #endif 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 static __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